WO2024081632A1

WO2024081632A1 - Systems and methods for processing ammonia

Info

Publication number: WO2024081632A1
Application number: PCT/US2023/076448
Authority: WO
Inventors: Joseph Kalyan Raj ISAC; Luiz Fernandes; Matthew Jacob MONTGOMERY
Original assignee: Amogy Inc.
Priority date: 2022-10-11
Filing date: 2023-10-10
Publication date: 2024-04-18

Abstract

Ammonia reforming systems and methods are disclosed herein. A storage tank is configured to store ammonia (NH₃). An electrically-heated reformer includes a first catalyst configured to reform the NH₃at a first target temperature range to generate a reformate stream comprising hydrogen (H₂) and nitrogen (N₂). An electrical heater is configured to heat the electrically-heated reformer to the first target temperature range. A combustion-heated reformer includes a second catalyst configured to reform the NH₃at a second target temperature range to generate additional H₂ and additional N₂ for the reformate stream. A combustion heater is configured to combust the reformate stream to heat the combustion-heated reformer.

Description

SYSTEMS AND METHODS FOR PROCESSING AMMONIA CROSS REFERENCE

[001] This application claims priority to U.S. Provisional Patent Application No. 63/415,222, filed October 11, 2022, which is incorporated herein by reference in its entirety for all purposes.

BACKGROUND

[002] As the world economy aims to decarbonize by 2050 or sooner, interest in zero-carbon (or carbon-neutral) energy systems has grown rapidly. Scalable zero-emission fuels (SZEFs; chemical fuels that are produced using renewable, zero-carbon energy) are of particular interest, since SZEFs can replace fuels used in hard-to-decarbonize sectors.

SUMMARY

[003] Hydrogen, being a scalable zero-emission fuel (SZEF), can be leveraged as clean energy to power various systems. Hydrogen can be synthetically produced without carbon emissions, for example, by electrolyzing freshwater using wind and solar energy.

[004] Hydrogen can provide advantages over other chemical fuels, such as diesel, gasoline, or jet fuel, which have specific energies of about 45 megajoules per kilogram (heat), as well as over lithium-ion batteries, which have specific energies of about 0.95 megajoule (MJ)/ kilogram (kg) (electrical). In contrast, hydrogen has a specific energy of over 140 MJ/kg (heat), such that 1 kg of hydrogen can provide the same amount of energy as about 3 kg of gasoline or kerosene. Thus, hydrogen reduces the amount of fuel (by mass) needed to provide a comparable amount of energy.

[005] Further, systems that consume hydrogen as a fuel generally produce benign or nontoxic byproducts such as water, and minimal or near zero greenhouse gas emissions (e.g., carbon dioxide and nitrous oxide), thereby reducing the environmental impacts of various systems (e.g., modes of transportation) that use hydrogen as a fuel source.

[006] Recognized herein are various limitations with hydrogen storage and production systems currently available. Although hydrogen has a relatively high gravimetric density (measured in MJ/kg), fuel storage systems for compressed and liquefied hydrogen are often complex due to specialized storage conditions.

[007] For example, storage of hydrogen may require tanks that can withstand high pressures (e.g., 350-700 bar or 5,000-10,000 pound per square inch (psi)), and/or may require cryogenic temperatures (since the boiling point of hydrogen at 1 atm of pressure is -252.8 °C). Additionally, hydrogen storage containers may be constructed using materials that are highly- specialized, costly, and difficult to develop, which may limit the ability to manufacture such hydrogen storage containers at a large scale. [008] Ammonia (NH3) is a SZEF that can be used as a hydrogen storage vector. Since ammonia can be stored at significantly lower pressures (and/or higher temperatures) than hydrogen, ammonia overcomes some of the aforementioned shortcomings of hydrogen. Further recognized herein are various limitations of conventional ammonia processing systems, which generally have slow startup times, non-ideal thermal characteristics, suboptimal ammonia conversion efficiencies, and high weight and volume requirements.

[009] In some aspects, the present disclosure is directed to ammonia reforming systems and methods. The ammonia reforming systems and methods described herein can address the abovementioned shortcomings of conventional systems for storing and/or releasing hydrogen for utilization as a fuel. The presently described ammonia reforming systems may generate high electrical power (about 5 kilowatts or greater), provide a high energy density (about 655 watt- hour (Wh)/ kilogram (kg) or greater by weight and about 447 watt-hour (Wh)/ liter (L) or greater by volume), and provide a high power density.

[0010] The present ammonia reforming systems and methods may advantageously enable the decarbonization of long-distance transportation where refueling can be difficult via other decarbonized methods (for example, on trucking routes longer than 500 miles, or on transoceanic shipping routes). Over such long-distance routes, using batteries to power motors may entail excessively long recharging times and excessive weight and volume requirements, which reduces revenues for ship operators by decreasing the space available for cargo. Additionally, using compressed hydrogen or liquid hydrogen over such long-distance routes may not be feasible due to the specialized hydrogen storage conditions described previously, as well as the large volume requirements for the hydrogen storage tanks.

[0011] Additionally, the present ammonia reforming systems and methods may advantageously provide combustion fuel for self-heating (i.e., auto-thermal heating). In other words, the ammonia reformers may be heated by the combustion of hydrogen extracted from the ammonia reforming itself, as opposed being heated by combustion of hydrocarbons (which undesirably emits greenhouse gases, nitrogen oxides (NO_X), and/or particulate matter). By reforming ammonia into hydrogen, a separate tank may not be required for storing combustion fuel (e.g., hydrocarbons or hydrogen).

[0012] Additionally, the present ammonia reforming systems and methods may advantageously provide a high purity reformate stream (e.g., at least about 99.9% H2/N2 mixture by molar fraction, or less than about 10 parts per million (ppm) of ammonia). This high purity is achieved by converting NH3 at a high efficiency (conferred by the effective design of the reforming reformer, as well as the reforming catalyst), and by utilizing an ammonia filter (e.g., adsorbents or membrane filter) to remove unconverted trace or residual ammonia. The high purity reformate stream (H2/N2 mixture, or H2 stream) may be consumed by a proton exchange membrane fuel cell (PEMFC) or other power generation device (e.g., internal combustion engine (ICE) or solid oxide fuel cell (SOFC)).

[0013] Additionally, the present ammonia reforming systems and methods are simple to operate and provides a high degree of safety. Ammonia may be provided to reformers using a single inlet (e.g., as opposed to a first inlet for a first reformer, a second inlet for a second reformer, and so on). Furthermore, a single stream of ammonia may pass through several reformers (e.g., first passing through a startup reformer, and then into a main reformer, or vice versa). This configuration may facilitate heat transfer from the reformers to the incoming ammonia stream (to vaporize the incoming ammonia stream), and may increase the ammonia conversion efficiency (i.e., by fully reforming the ammonia stream). In some embodiments, the ammonia flow rate may be controlled at the single inlet, and in the case of a major fault or dangerous event, the ammonia flow may be quickly shut off via the single inlet.

[0014] In one aspect, the present disclosure is directed to an ammonia reforming system. In some embodiments, the ammonia reforming system comprises one or more storage tanks configured to store ammonia (NH3), one or more electrically-heated reformers in fluid communication with the one or more storage tanks, one or more electrical heaters configured to heat the one or more electrically-heated reformers to the first target temperature range, one or more combustion-heated reformers in fluid communication with the one or more storage tanks, and one or more combustion heaters configured to combust the reformate stream to heat the one or more combustion-heated reformers. In some embodiments, the one or more electrically- heated reformers comprise one or more first catalysts configured to reform the NH3 at a first target temperature range to generate a reformate stream comprising hydrogen (EE) and nitrogen (N2). In some embodiments, the one or more combustion-heated reformers comprise one or more second catalysts configured to reform the NH3 at a second target temperature range to generate additional EE and additional N2 for the reformate stream.

[0015] In some embodiments, the one or more combustion heaters each comprise a flame tube, and the one or more combustion-heated reformers each comprise an inner shell and an outer shell. In some embodiments, the flame tube, the inner shell, and the outer shell are concentrically aligned along a longitudinal axis so that the inner shell is adjacent to the flame tube, and the outer shell is adjacent to the inner shell. In some embodiments, the system further comprises one or more heat exchanging elements in at least one of the flame tube, the inner shell, or the outer shell. In some embodiments, the one or more heat exchanging elements are configured to transfer heat from a combustion product gas to the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the one or more heat exchanging elements comprise at least one of: one or more ceramic or metallic fins or one or more ceramic or metallic beads. In some embodiments, a particle size of each of the one or more ceramic or metallic beads comprises of from about 0.1 millimeter (mm) to about 5 mm. In some embodiments, the one or more ceramic or metallic fins comprise a vertical, a horizontal, a helical, or curved shape. In some embodiments, the one or more ceramic or metallic fins comprising the helical or curved shape are positioned in the flame tube, to swirl the combustion product gas and thereby improve transfer of the heat to the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the one or more ceramic or metallic fins comprising the helical or curved shape wrap around inner walls of the flame tube to swirl the combustion product gas.

[0016] In some embodiments, the one or more heat exchanging elements comprise at least one of: one or more ceramic or metallic honeycomb structures; one or more ceramic or metallic meshes; or one or more coiled springs. In some embodiments, a coating of the one or more heat exchanging elements comprises the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the flame tube, the inner shell, and the outer shell each comprise at least one of a metal or a ceramic. In some embodiments, the metal comprises at least one of stainless steel, tungsten, titanium, or alloys thereof. In some embodiments, the ceramic comprises at least one of alumina, silicon carbide or aluminum carbide. In some embodiments, the flame tube, the inner shell, and the outer shell each comprise a length ranging of from about 0.2 meters to about 10 meters. In some embodiments, walls of the flame tube, the inner shell, and the outer shell each comprise a thickness of from about 1 mm to about 10 cm. In some embodiments, an outer diameter of the inner shell, with respect to the longitudinal axis, comprises of from about 1.1 times an outer diameter of the flame tube to about 3 times the outer diameter of the flame tube. In some embodiments, a ratio of a volume of the outer shell to a volume of the inner shell comprises of from about 1 : 1 to about 5: 1.

[0017] In some embodiments, the system further comprises a preheating conduit in the flame tube, wherein the preheating conduit is concentrically aligned along the longitudinal axis. In some embodiments, the preheating conduit is configured to transfer heat from (1) combustion product gas in the flame tube to (2) an incoming stream of the NH3 from the one or more storage tanks, so that the NH3 is preheated for decomposition in the one or more combustion-heated reformers or the one or more electrically-heated reformers. In some embodiments, the preheating conduit is configured to transfer heat from (1) combustion product gas in the flame tube to (2) a stream of air, so that the air is preheated for the combustion in the flame tube. In some embodiments, the preheating conduit, the one or more electrically-heated reformers and the one or more combustion-heated reformers are in fluid communication and configured so that an incoming stream of the NH3 passes the preheating conduit, then subsequently passes the one or more catalysts of the one or more electrically-heated reformers, and then subsequently passes the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the preheating conduit comprises a plurality of injection holes along a length of the preheating conduit, wherein the plurality of injection holes are configured to inject air into the flame tube in a staged injection pattern. In some embodiments, the plurality of injection holes are variably sized along the length of the flame tube to enable different injection velocities of the air into the flame tube. In some embodiments, the plurality of injection holes are angled to improve mixing of the air and the reformate stream. In some embodiments, the plurality of injection holes are positioned so that the air is injected tangentially with respect to a curved wall of the preheating conduit to swirl the air and improve mixing of the air and the reformate stream. In some embodiments, a diameter of the preheating conduit comprises of from about 0.05 times an inner diameter of the flame tube to about 0.9 times the inner diameter of the flame tube. In some embodiments, a length of the preheating conduit comprises of from about 0.75 times a length of the flame tube to about 2 times the length of the flame tube. In some embodiments, a shape of the preheating conduit comprises a straight tube shape, a helical shape, a U shape, or a W shape. [0018] In some embodiments, the one or more combustion heaters comprise a supply-tube configured for U-turn combustion. In some embodiments, the supply tube is at least partially in the flame tube of the one or more combustion heaters. In some embodiments, the supply tube comprises one or more inlets configured to receive the reformate stream and air. In some embodiments, the one or more inlets are substantially adjacent to a first side of the one or combustion heaters. In some embodiments, the supply tube comprises one or more outlets configured to direct the reformate stream and the air into the flame tube. In some embodiments, the one or more outlets are substantially adjacent to a second side of the one or more combustion heaters, the second side being opposite to the first side. In some embodiments, the supply tube and the flame tube are configured in a U-turn combustion configuration so that the reformate stream and air pass through the supply tube along a first direction from the first side to the second side, and combustion product gas passes through the flame tube along a second direction from the second side to the first side.

[0019] In some embodiments, the supply tube comprises one or more reformate supply tubes and one or more air supply tubes. In some embodiments, the one or more reformate supply tubes and one or more air supply tubes have same diameters and lengths. In some embodiments, the supply tube comprises one or more reformate supply tubes and one or more air supply tubes. In some embodiments, the one or more reformate supply tubes and the one or more air supply tubes have different diameters and lengths. In some embodiments, the supply tube comprises one or more reformate supply tubes and one or more air supply tubes. In some embodiments, a length of each of the one or more reformate supply tubes and the one or more air supply tubes comprises of from about 0.1 to about 1 times the length of the supply tube. In some embodiments, the one or more combustion heaters comprise a first inlet configured to receive a first reformate stream, and a second inlet configured to receive a second reformate stream. In some embodiments, the first reformate stream comprises the reformate stream directed from at least one of the one or more electrically-heated reformers or the one or more combustion-heated reformers. In some embodiments, the second reformate stream comprises the reformate stream directed from an outlet of one or more fuel cells. In some embodiments, the first inlet and the second inlet are configured to separate the first reformate stream and the second reformate stream so that trace ammonia in the first reformate stream is prevented from flowing to the one or more fuel cells.

[0020] In some embodiments, the system further comprises one or more heat exchangers. In some embodiments, the one or more heat exchangers are configured to exchange heat between one or more incoming streams of the NH3 from the one or more storage tanks and at least one of: the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers; the one or more combustion heaters; one or more combustion exhausts of the one or more combustion heaters; one or more adsorbents configured to filter out ammonia from the reformate stream; one or more fuel cells configured to generate electricity using at least part of the reformate stream; and one or more streams of air from one or more air supply units. In some embodiments, exchanging the heat evaporates and/or preheats the one or more incoming streams of the NH3. In some embodiments, the one or more heat exchangers are configured to exchange heat between the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers, and at least one of: one or more incoming streams of air from one or more air supply units; one or more adsorbents configured to filter out ammonia from the reformate stream. In some embodiments, exchanging the heat cools the reformate stream. In some embodiments, the one or more heat exchangers are configured to exchange heat between one or more adsorbents configured to filter out the ammonia from the reformate stream, and at least one of: one or more electrical heaters; one or more combustion heaters; one or more combustion heaters of the one or more combustion heated reformers; one or more combustion exhausts of the one or more combustion heaters; or the reformate stream from at least one of the one or more combustion- heated reformers or the one or more electrically-heated reformers. In some embodiments, exchanging the heat regenerates the one or more adsorbents or releases adsorbed ammonia from the one or more adsorbents.

[0021] In some embodiments, ammonia released from the one or more adsorbents is combusted in the one or more combustion heaters, filtered by one or more ammonia scrubbers, dissolved by a water tank, or vented to the atmosphere. In some embodiments, one or more combustion exhausts of the one or more combustion-heated reformers are configured to exchange heat with the one or more adsorbents by at least one of: contacting combustion product gas with the one or more adsorbents; contacting combustion product gas with one or more heat exchanging elements, wherein the one or more heat exchanging elements are configured to transfer heat from the combustion product gas to the one or more adsorbents; or contacting combustion product gas with an intermediate fluid, wherein the intermediate fluid is configured to transfer heat from the combustion product gas to the one or more adsorbents.

[0022] In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more adsorbents configured to filter out the ammonia from one or more exit flows from the one or more reformers, and at least one of: one or more incoming streams of the NH3 from the one or more storage tanks; one or more streams of air from one or more air supply units; or ambient air. In some embodiments, exchanging the heat cools the one or more adsorbents. In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more adsorbents and the ambient air using an intermediate fluid. In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more incoming air flows from the one or more air supply units, and at least one of: the one or more combustion heaters; the one or more electrical heaters; the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers; and the one or more fuel cells configured to generate electricity from at least part of the reformate stream. In some embodiments, exchanging the heat preheats the one or more streams of air from the one or more air supply units.

[0023] In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more storage tanks, and at least one of: the one or more combustion heaters; the one or more electrical heaters; one or more combustion exhausts of the one or more combustion heaters; the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers; ambient air; one or more streams of air from the one or more air supply units; and the one or more fuel cells configured to generate electricity from the at least part of the reformate stream. In some embodiments, exchanging the heat evaporates the NH3 and/or increases a pressure of the one or more storage tanks.

[0024] In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more combustion heaters, and at least one of: one or more incoming streams of the NH3 from the one or more storage tanks; and one or more incoming streams of air from one or more air supply units. In some embodiments, exchanging the heat cools the one or more combustion heaters. In some embodiments, the one or more heat exchangers are configured to exchange heat between the one or more fuel cells configured to generate electricity from the at least part of the reformate stream, and at least one of: one or more incoming streams of the NH3 from the one or more storage tanks; one or more incoming streams of air from the one or more air supply units; and ambient air. In some embodiments, exchanging the heat cools the one or more fuel cells. In some embodiments, the one or more heat exchangers are configured to exchange heat from the one or more fuel cells using an intermediate fluid. In some embodiments, the one or more heat exchangers are configured in at least one of: a counter flow configuration, a cross flow configuration, or a parallel flow configuration.

[0025] In some embodiments, the system further comprises one or more bluff bodies in the one or more combustion heaters, wherein the one or more bluff bodies are configured to absorb heat from combustion product gas in the one or more combustion heaters. In some embodiments, a shape of a cross-section of the one or more bluff bodies comprises a circle, an ellipse, a square, a diamond, a triangle, or any combination thereof. In some embodiments, the one or more bluff bodies comprise a metal or ceramic. In some embodiments, a width of the one or more bluff bodies comprises of from about 0.1 to about 0.95 times an outer diameter of a flame tube of the one or more combustion heaters. In some embodiments, a length of the one or more bluff bodies comprises of from about 0.05 to about 0.5 times a length of a flame tube of the one or more combustion heaters. In some embodiments, the one or more bluff bodies are adjacent to an inlet of the one or more combustion heaters to cool the combustion product gas and reduce thermal stress on walls of the one or more combustion heaters. In some embodiments, the one or more bluff bodies comprise one or more heat exchanging conduits configured to receive an incoming stream of the NH3 from the one or more storage tanks. In some embodiments, the heat exchanging conduits are configured to further absorb the heat from the combustion product gas to heat the incoming stream of the NH3. In some embodiments, the one or more heat exchanging conduits comprise a helical shape or a serpentine shape to improve the absorption of the heat from the combustion product gas to heat the incoming stream of the NH3. In some embodiments, the one or more heat exchanging conduits comprise one or more catalysts configured to decompose the incoming stream of the NH3.

[0026] In some embodiments, each of the one or more combustion heaters include one or more preheating conduits. In some embodiments, each of the one or more preheating conduits is concentrically aligned along a longitudinal axis of the one or more combustion heaters. In some embodiments, the one or more heat exchanging conduits of the one or more bluff bodies are in fluid communication with the one or more preheating conduits. In some embodiments, the one or more preheating conduits of the one or more combustion heaters and the one or more heat exchanging conduits of the one or more bluff bodies are configured so that the incoming stream of the NH3 passes through the heat exchanging conduits, and then subsequently passes through the preheating conduit. In some embodiments, at least a portion of the one or more combustion heaters comprise hollow sidewalls in fluid communication with the heat exchanging conduits of the one or more bluff bodies.

[0027] In some embodiments, the hollow sidewalls are configured to receive an incoming stream of the NH3 from the one or more storage tanks to preheat the incoming stream of the NH3, before the incoming stream of the NH3 passes through the heat exchanging conduits of the one or more bluff bodies. In some embodiments, at least a portion of the one or more combustion heaters comprise hollow sidewalls in fluid communication with one or more air supply units configured to provide air to the hollow sidewalls. In some embodiments, the hollow sidewalls comprise a plurality of injection holes adjacent to inside the one or more combustion heaters. In some embodiments, the plurality of injection holes are configured to inject the air into inside the one or more combustion heaters in a staged injection pattern. In some embodiments, the portion including the hollow sidewalls comprising the plurality of injection holes is adjacent to an inlet of the one or more combustion heaters to cool the combustion product gas and reduce thermal stress on walls of the one or more combustion heaters, and to preheat the air for combustion in the one or more combustion heaters.

[0028] In some embodiments, the system further comprises fluidized particles in the one or more combustion heaters, wherein the fluidized particles are configured to transfer heat from (1) combustion product gas in the one or more combustion heaters to (2) the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the system further comprises a fluidization funnel positioned adjacent to an inlet of the one or more combustion heaters. In some embodiments, the fluidization funnel is configured to receive or hold the fluidized particles. In some embodiments, the inlet is configured to receive one or more streams comprising at least one of the hydrogen or air. In some embodiments, the fluidization funnel is configured to be in fluid communication with the inlet, so that when the one or more streams pass the fluidization funnel, the one or more streams push the fluidized particles into the one or more combustion heaters to absorb heat from the combustion product gas and transfer the heat to the one or more catalysts of the one or more combustion-heated reformers. In some embodiments, the fluidized particles comprise at least one of sand, ceramic particles, or metallic particles. In some embodiments, a particle size of each of the fluidized particles comprises at least about 100 microns. In some embodiments, a particle size of each of the fluidized particles comprises at most about 2 millimeters. In some embodiments, the system further comprises a grated or perforated plate in or at a combustion exhaust of the one or more combustion heaters. In some embodiments, the grated or perforated plate is configured to prevent escape of the fluidized particles from the one or more combustion heaters. In some embodiments, the system further comprises one or more water collection devices in fluid communication with one or more combustion exhausts of the one or more combustion heaters. In some embodiments, the one or more water collection devices are configured to remove water from combustion product gas. [0029] In some embodiments, the system further comprises a water collection tank configured to store the water removed from the combustion product gas. In some embodiments, the system further comprises one or more electrolyzers configured to electrolyze the stored water removed from the combustion product gas to generate additional hydrogen (H2). In some embodiments, the system further comprises one or more fuel cells configured to generate electricity from the at least part of the generated hydrogen from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers. In some embodiments, an inlet of the one or more fuel cells is configured to be in fluid communication with the water collection tank so that the water humidifies the one or more fuel cells. In some embodiments, an outlet of the one or more fuel cells is configured to be in fluid communication with the water collection tank so that the water is collected in the water collection tank from the outlet of the one or more fuel cells. In some embodiments, the system further comprises one or more thermoelectric generators in fluid communication with one or more combustion exhausts of the one or more combustion heaters. In some embodiments, the one or more thermoelectric generators are configured to generate electricity using heat of combustion product gas.

[0030] In some embodiments, the system further comprises a compressor in fluid communication with an inlet of the one or more combustion heaters. In some embodiments, the compressor is configured to compress air and provide the compressed air to the one or more combustion heaters for combustion. In some embodiments, the compressor is configured to be powered using the electricity generated by the one or more thermoelectric generators. In some embodiments, the system further comprises one or more turbochargers or turbines in fluid communication with one or more combustion exhausts of the one or more combustion heaters. In some embodiments, the one or more turbochargers or turbines are configured to be driven using combustion product gas to compress air. In some embodiments, the one or more turbochargers or turbines are in fluid communication with an inlet of the one or more combustion heaters. In some embodiments, the one or more turbochargers are configured to provide the compressed air to the one or more combustion heaters for combustion. In some embodiments, the one or more combustion heaters comprise a burner head including one or more primary air inlets configured to receive a primary air stream, and one or more reformate inlets configured to receive the reformate stream.

[0031] In some embodiments, an air preheating channel is positioned in the burner head. In some embodiments, the air preheating channel includes a secondary inlet configured to receive a secondary air stream. In some embodiments, the secondary air stream cools the one or more combustion heaters at, near or adjacent to the burner heard. In some embodiments, the air preheating channel includes a plurality of injection holes along a length of the air preheating channel. In some embodiments, the plurality of injection holes are configured to inject the secondary air stream into the one or more combustion heaters. In some embodiments, the secondary inlet is further configured to receive a mixture of (1) the secondary air stream and (2) the reformate stream.

[0032] In some embodiments, an NH3 preheating channel is positioned in the burner head. In some embodiments, the NH3 preheating channel includes an inlet configured to receive an incoming NH3 stream. In some embodiments, the incoming NH3 stream cools the one or more combustion heaters at, near or adjacent to the burner head. In some embodiments, the incoming NH3 stream, after being preheated in the NH3 preheating channel, is configured to be directed to the one or more combustion-heated reformers or the one or more electrically-heated reformers for decomposition.

[0033] In some embodiments, the one or more combustion heaters comprise inner sidewalls, outer sidewalls, and a copper layer between the inner sidewalls and the outer sidewalls. In some embodiments, the copper layer is configured to evenly distribute heat from combustion product gas in the one or more combustion heaters to the one or more catalysts of the one or more combustion-heated reformers.

[0034] In some embodiments, the system further comprises one or more adsorbents configured to remove the ammonia from the reformate stream. In some embodiments, regeneration of the one or more adsorbents is initiated when a measured temperature of the one or more adsorbents is equal to or greater than a threshold adsorbent temperature. In some embodiments, the measured temperature of the one or more adsorbents is measured at, in, or adjacent to at least one of: an inlet of the one or more adsorbents, an outlet of the one or more adsorbents, between the inlet and the outlet, or a filtered reformate stream output from the one or more adsorbents. In some embodiments, the threshold adsorbent temperature is at least about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than an ambient temperature. In some embodiments, the threshold adsorbent temperature is at most about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than an ambient temperature. In some embodiments, the first catalyst and the second catalyst are same.

[0035] In another aspect, the present disclosure is directed to a furnace ammonia reforming system. In some embodiments, the furnace ammonia reforming system comprises: one or more storage tanks configured to store ammonia (NH3); a furnace comprising one or more reformers; one or more burners in or in fluid communication with the furnace configured to combust a fuel to heat the furnace; an inlet manifold configured to direct the NH3 from the one or more storage tanks to the one or more reformers; and an outlet manifold configured to direct the H2 and the N2 out of the one or more reformers. In some embodiments, the one or more reformers comprise one or more catalysts configured to decompose the NH3 to generate hydrogen (H2) and nitrogen (N2). In some embodiments, each of the one or more reformers includes an inner chamber and an outer chamber comprising the one or more catalysts. In some embodiments, the inner chamber is in fluid communication with the inlet manifold, and the outer chamber is in fluid communication with the outlet manifold. In some embodiments, the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outer chamber, the NH3 passes the inner chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the outer chamber along a second direction from the second side to the first side. In some embodiments, each of the one or more reformers includes an inner chamber and an outer chamber comprising the one or more catalysts. In some embodiments, the inner chamber is in fluid communication with the outlet manifold, and the outer chamber is in fluid communication with the inlet manifold. In some embodiments, the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outlet chamber, the NH3 passes the outer chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the inner chamber along a second direction from the second side to the first side.

[0036] In some embodiments, the system further comprises a convective heat exchanger in fluid communication with the furnace chamber and configured to receive combustion product gas from the one or more burners. In some embodiments, the convective heat exchanger is configured to transfer heat from the combustion product gas to an incoming stream of the NH3 from the one or more storage tanks to evaporate and/or preheat the incoming stream of the NH3. In some embodiments, the one or more reformers comprise one or more U-shaped reformers. In some embodiments, the one or more U-shaped reformers each comprise a bend. In some embodiments, the furnace comprises a partition configured to divide the furnace into a first chamber and a second chamber.

[0037] In some embodiments, each of the one or more U-shaped reformers includes an inner chamber and an outer chamber comprising the one or more catalysts. In some embodiments, the inner chamber is in fluid communication with the inlet manifold, and the outer chamber is in fluid communication with the outlet manifold. In some embodiments, the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outer chamber, the NH3 passes the inner chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the outer chamber along a second direction from the second side to the first side. In some embodiments, each of the one or more U-shaped reformers includes an inner chamber and an outer chamber comprising the one or more catalysts. In some embodiments, the inner chamber is in fluid communication with the outlet manifold, and the outer chamber is in fluid communication with the inlet manifold. In some embodiments, the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outlet chamber, the NH3 passes the outer chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the inner chamber along a second direction from the second side to the first side.

[0038] In another aspect, the present disclosure is directed to a heat exchanger reformer. In some embodiments, the heat exchanger reformer comprises one or more reaction channels in fluid communication with an ammonia reformer configured to decompose ammonia using one or more catalysts, and one or more heat exchanging channels with one or more extended or corrugated surfaces configured to transfer heat from a fluid stream to the one or more reaction channels. In some embodiments, the one or more reaction channels comprise one or more extended or corrugated surfaces coated or filled with the one or more catalysts configured to decompose the ammonia. In some embodiments, a spacing between one or more extended or corrugated surfaces comprises: at least about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some embodiments, a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some embodiments, a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some embodiments, a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some embodiments, the heat exchanger reformer comprises at least one of plate-type heat exchanger, shell-and-tube type heat exchanger, or tubein-tube type heat exchanger. In some embodiments, the one or more reaction channels and/or the one or more heat exchanging channels comprise one or more metal meshes configured to improve transfer of the heat. In some embodiments, a portion of the heat exchanger is configured to evaporate or preheat an incoming stream of the ammonia.

[0039] In some embodiments, the one or more catalysts comprise at least one of: ruthenium or nickel as an active metal; and/or an active metal comprising a diameter of at least about 1 nm, 10 nm, 100 nm, or 1000 nm. In some embodiments, the active metal comprising a diameter of at most about 1 nm, 10 nm, 100 nm, or 1000 nm.

[0040] In another aspect, the present disclosure is directed to a multi-channel reformer. In some embodiments, the multi-channel reformer comprises: a housing comprising a plurality of inner shells and at least one outer shell; one or more heating elements embedded in each of the plurality of inner shells; and an ammonia (NH3) reforming catalyst in at least one of the plurality of inner shells or the at least one outer shell. In some embodiments, the housing comprises a rectangular cross-sectional shape. In some embodiments, the housing comprises a circular cross- sectional shape. In additional embodiments are described methods comprising reforming ammonia using the system disclosed herein.

[0041] In another aspect, the present disclosure is directed to a method comprising converting ammonia into electrical power using systems disclosed herein.

[0042] In another aspect, the present disclosure is directed to a method comprising converting ammonia into hydrogen using systems disclosed herein.

[0043] In another aspect, the present disclosure is directed to an ammonia reforming system, comprising: a first reformer configured to reform ammonia to generate a first reformate stream comprising hydrogen and nitrogen; and a combustion heater configured to combust a first portion of the first reformate stream and generate a combustion exhaust to heat the first reformer. [0044] In some embodiments, the system further comprises a second reformer configured to generate a second reformate stream comprising hydrogen and nitrogen, wherein the combustion heater is configured to combust the second reformate stream to heat the first reformer.

[0045] In some embodiments, the first reformer comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[0046] In some embodiments, the heat exchanging element comprises a helical feature.

[0047] In some embodiments, the helical feature comprises a wire or a vane.

[0048] In some embodiments, the first reformer and the combustion heater are aligned concentrically along a longitudinal axis.

[0049] In some embodiments, the combustion heater at least partially surrounds the first reformer.

[0050] In some embodiments, the first reformer includes an inner shell and an outer shell.

[0051] In some embodiments, the outer shell at least partially surrounds the inner shell.

[0052] In some embodiments, the combustion heater at least partially surrounds the outer shell. [0053] In some embodiments, the combustion heater, the inner shell, and the outer shell are aligned along a longitudinal axis.

[0054] In some embodiments, a first radial distance of the inner shell with respect to the longitudinal axis is smaller than a second radial distance of the outer shell with respect to the longitudinal axis, so that the outer shell extends further from the longitudinal axis compared to the inner shell.

[0055] In some embodiments, a second radial distance of the outer shell with respect to the longitudinal axis is smaller than a third radial distance of the combustion heater with respect to the longitudinal axis, so that the combustion heater extends further from the longitudinal axis compared to the outer shell.

[0056] In some embodiments, the system further comprises a blockage structure positioned in the inner shell.

[0057] In some embodiments, the blockage structure has a cylindrical or rectangular cuboid shape. [0058] In some embodiments, the blockage structure comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[0059] In some embodiments, the heat exchanging element comprises a helical feature.

[0060] In some embodiments, the helical feature comprises a wire or a vane.

[0061] In some embodiments, the system further comprises a refractory fiber material on an inner surface of the combustion heater.

[0062] In some embodiments, the system further comprises a metal lining on an inner surface of the combustion heater.

[0063] In some embodiments, the system further comprises an insulating material on an outer surface of the first reformer.

[0064] In some embodiments, the insulating material covers less than half a surface area of the first reformer.

[0065] In some embodiments, the combustion heater comprises a primary air inlet configured to receive a primary air stream, a reformate inlet configured to receive the first reformate stream, and secondary air inlet configured to receive a secondary air stream.

[0066] In some embodiments, the primary air inlet and the reformate inlet form an annulus, and the secondary air inlet is positioned at a center of the annulus.

[0067] In some embodiments, the secondary air inlet comprises a cylindrical conduit.

[0068] In some embodiments, the secondary inlet is further configured to receive a mixture of the secondary air stream and the first reformate stream.

[0069] In some embodiments, the system further comprises an air preheating section at least partially surrounding the combustion heater configured to receive an air stream.

[0070] In some embodiments, the air preheating section forms an annulus.

[0071] In some embodiments, the air preheating section is in thermal communication with the combustion heater, and configured so that the combustion exhaust in the combustion heater transfers heat to the air stream in the air preheating section.

[0072] In some embodiments, the air stream in the air preheating section and the combustion exhaust in the combustion heater are arranged in a counter flow configuration.

[0073] In some embodiments, the system further comprises a plurality of injection holes configured to inject the air stream into the combustion heater and toward the first reformer from the air preheating section.

[0074] In some embodiments, the injection holes are positioned along a wall separating the air preheating section and the combustion heater. [0075] In some embodiments, the injection holes are variably sized along a length of the combustion heater.

[0076] In some embodiments, the injection holes are progressively smaller along the length of the combustion heater.

[0077] In some embodiments, the system further comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[0078] In some embodiments, the heat exchanging element comprises a helical feature.

[0079] In some embodiments, the helical feature winds around an outer surface of the first reformer.

[0080] In some embodiments, the helical feature winds around an inner surface of the first reformer.

[0081] In some embodiments, the helical feature comprises a wire or a vane.

[0082] In some embodiments, the system further comprises a combustion heating section configured to receive the combustion exhaust from the combustion heater, wherein the combustion heating section is in thermal communication with the first reformer.

[0083] In some embodiments, the combustion heater and the combustion heating section are separate structures.

[0084] In some embodiments, the combustion heater is configured to be attached to and detached from the combustion heating section.

[0085] In some embodiments, the combustion heater and the first reformer are separate structures.

[0086] In some embodiments, the combustion heater is configured to be attached to and detached from the first reformer.

[0087] In some embodiments, the combustion heater is configured so that a flame produced by the combustion heater does not impinge the first reformer.

[0088] In some embodiments, the system further comprises a partition in the combustion heating section, wherein the partition includes a plurality of injection ports configured to inject the combustion exhaust toward the first reformer.

[0089] In some embodiments, the system further comprises an exhaust conduit configured to transfer the combustion exhaust from the combustion heater to the combustion heating section. [0090] In some embodiments, the exhaust conduit includes a plurality of injection holes configured to inject the combustion exhaust into the combustion heating section and toward the first reformer. [0091] In some embodiments, the injection holes are variably sized along a length of the exhaust conduit.

[0092] In some embodiments, the injection holes are progressively smaller along the length of the exhaust conduit.

[0093] In some embodiments, the first reformer includes an inner shell and an outer shell.

[0094] In some embodiments, the first reformer is configured so that the first reformate stream travels in a U-turn path between the outer shell and the inner shell.

[0095] In some embodiments, the combustion heating section is configured so that the combustion exhaust contacts a wall of the inner shell to transfer heat to the inner shell.

[0096] In some embodiments, combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the outer shell to transfer heat to the outer shell after contacting the wall of the inner shell.

[0097] In some embodiments, the combustion heating section is configured so that the combustion exhaust contacts a wall of the outer shell to transfer heat to the outer shell .

[0098] In some embodiments, the combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the inner shell to transfer heat to the inner shell after contacting the wall of the outer shell.

[0099] In some embodiments, the system further comprises an air preheating section at least partially surrounding the combustion heating section configured to receive an air stream.

[00100] In some embodiments, the air preheating section forms an annulus.

[00101] In some embodiments, the air preheating section is in thermal communication with the combustion heating section, and configured so that the combustion exhaust in the combustion heating section transfers heat to the air stream in the air preheating section.

[00102] In some embodiments, the air stream in the air preheating section and the combustion exhaust in the combustion heating section are arranged in a counter flow configuration.

[00103] In some embodiments, the system further comprises an NH3 preheating section configured to receive the ammonia before the ammonia is reformed in the first reformer .

[00104] In some embodiments, the NH3 preheating section is in thermal communication with the combustion heater, and is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 preheating section.

[00105] In some embodiments, the system further comprises a combustion heating section configured to receive the combustion exhaust after the combustion exhaust passes through the combustion heater. [00106] In some embodiments, the combustion heating section is in thermal communication with the first reformer, and is configured to transfer heat from the combustion exhaust to the first reformer.

[00107] In some embodiments, the combustion heating section at least partially surrounds the first reformer .

[00108] In some embodiments, the NH3 preheating section at least partially surrounds the combustion heater.

[00109] In some embodiments, the combustion heater at least partially surrounds the NH3 preheating section.

[00110] In some embodiments, the NH3 preheating section includes an inner section and an outer section .

[00111] In some embodiments, the inner section is a cylindrical conduit, and the outer section is an annulus.

[00112] In some embodiments, the ammonia in the inner section and the ammonia in the outer section are in a counter flow configuration.

[00113] In some embodiments, the outer section is configured to receive the ammonia stream, and the inner section is configured to output the ammonia stream.

[00114] In some embodiments, the NH3 preheating section further includes an NH3 injection section in thermal communication with the combustion heater, wherein the NH3 injection section is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 injection section.

[00115] In some embodiments, the system further comprises a plurality of injection holes along a wall separating the NH3 injection section and the outer section, and configured to inject the ammonia into the NH3 injection section and toward the combustion heater.

[00116] In some embodiments, the NH3 preheating section comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the ammonia in the preheating section.

[00117] In some embodiments, the heat exchanging element comprises a helical feature.

[00118] In some embodiments, the helical feature winds around the NH3 preheating section.

[00119] In some embodiments, the helical feature comprises a wire or a vane.

[00120] In some embodiments, the helical feature has a pitch that varies.

[00121] In some embodiments, the pitch of the helical feature is progressively smaller along a length of the NH3 preheating section. [00122] In some embodiments, the first reformer at least partially surrounds the NH3 preheating section.

[00123] In some embodiments, the first reformer at least partially surrounds the combustion heater and the preheating section.

[00124] In some embodiments, the system further comprises an output conduit at least partially inside the first reformer configured to receive the first reformate stream .

[00125] In some embodiments, the output conduit is configured to transfer the first reformate stream from a first side of the first reformer to a second side of the first reformer opposite to the first side.

[00126] In some embodiments, the system further comprises a cooling substance configured to absorb heat from the first reformate stream.

[00127] In some embodiments, the system further comprises a cooling chamber including the cooling substance therein, wherein the cooling chamber separates the cooling substance from an NH3 reforming catalyst in the first reformer.

[00128] In some embodiments, the system further comprises a transfer conduit at least partially inside the first reformer configured to receive the first reformate stream, wherein the transfer conduit is configured to transfer the first reformate stream from the NH3 reforming catalyst to the cooling substance in the cooling chamber.

[00129] In some embodiments, the cooling substance comprises a ceramic or a metal.

[00130] In some embodiments, the cooling substance comprises beads or pellets.

[00131] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

INCORPORATION BY REFERENCE

[00132] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material. BRIEF DESCRIPTION OF THE DRAWINGS

[00133] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings, of which:

[00134] FIGS. 1A-4B are block diagrams illustrating an ammonia reforming system, in accordance with one or more embodiments of the present disclosure.

[00135] FIG. 5 is a schematic diagram illustrating a combustion-heated reformer including a combustion heater, in accordance with one or more embodiments of the present disclosure.

[00136] FIG. 6 is a schematic diagram illustrating a conduit for preheating ammonia in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00137] FIG. 7 is a schematic diagram illustrating a conduit for preheating air in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00138] FIG. 8 is a schematic diagram illustrating a conduit including a plurality of holes for injecting air into the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00139] FIGS. 9A-9C are schematic diagrams illustrating an electrically-heated reformer in fluid communication with the combustion-heated reformer shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00140] FIGS. 10-12 are schematic diagrams illustrating various heat exchangers in addition to the combustion-heated reformer shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00141] FIGS. 13-15 are schematic diagrams illustrating various bluff bodies positioned inside the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00142] FIG. 16 is a schematic diagram illustrating a funnel configured to inject fluidized particles into the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00143] FIGS. 17A-D are schematic diagrams illustrating a supply tube configured for a U-turn combustion in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00144] FIG. 18 is a schematic diagram illustrating a burner head including separate ports in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00145] FIGS. 19-21 are schematic diagrams illustrating various configurations for regenerating the ammonia filter that utilize heat from the exhaust of the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00146] FIGS. 22-23 are schematic diagrams illustrating various configurations for cooling the ammonia filter in addition to the combustion-heated reformer shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00147] FIG. 24 is a schematic diagram illustrating a water extraction device that extracts water from the exhaust of the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00148] FIG. 25 is a schematic diagram illustrating a thermoelectric generator that utilizes heat from the exhaust of the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00149] FIG. 26 is a schematic diagram illustrating a turbocharger that utilizes the exhaust of the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00150] FIGS. 27-28 are schematic diagrams illustrating a burner head with preheating conduits in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00151] FIGS. 29-30 are schematic diagrams illustrating heat exchanging elements in the combustion-heated reformer shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00152] FIG. 31 is a schematic diagram illustrating heat exchanging elements in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00153] FIG. 32 is a schematic diagram illustrating heat exchanging fins in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00154] FIG. 33 is a schematic diagram illustrating radiant walls in the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00155] FIG. 34A is schematic diagram illustrating a cladding comprising a high thermal conductivity material positioned between two stainless steel shells of the combustion heater shown in FIG. 5, in accordance with one or more embodiments of the present disclosure.

[00156] FIG. 34B is a conceptual image illustrating advantageous thermal distribution conferred by the cladding shown in FIG. 34A, in accordance with one or more embodiments of the present disclosure.

[00157] FIGS. 35A-35G are schematic diagrams illustrating a furnace ammonia reforming system, in accordance with one or more embodiments of the present disclosure.

[00158] FIGS. 36A-36B are schematic diagrams illustrating a heat exchanger reformer, in accordance with one or more embodiments of the present disclosure.

[00159] FIGS. 37A-39A are schematic diagrams illustrating multi-channel reformers, in accordance with one or more embodiments of the present disclosure.

[00160] FIGS. 39B-39C are plots illustrating reforming energy efficiency and ammonia conversion efficiency of the multi-channel reformers shown in FIG. 39A, in accordance with one or more embodiments of the present disclosure.

[00161] FIGS. 40A-40F are schematic diagrams illustrating various externally-heated reformer configurations, in accordance with one or more embodiments of the present disclosure.

[00162] FIGS. 41A-41E are schematic diagrams illustrating various reformer configurations where the reformer is decoupled from the combustion heater, in accordance with one or more embodiments of the present disclosure.

[00163] FIGS. 42A-42D are schematic diagrams illustrating various reformer configurations that include an ammonia preheating section, in accordance with one or more embodiments of the present disclosure.

[00164] FIG. 43 is a computer system that is programmed or otherwise configured to implement methods and systems provided herein.

DETAILED DESCRIPTION

[00165] While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed. It should be understood that any of the embodiments, configurations and/or components described with respect to a particular figure may be combined with other embodiments, configurations, and/or components described with respect to other figures.

[00166] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (and vice versa), unless the context clearly indicates otherwise. For example, “a,” “an,” and “the” may be construed as “one or more.”

[00167] The present disclosure may be divided into sections using headings. The headings should not be construed to limit the present disclosure, and are merely present for organization and clarity purposes.

[00168] The expressions “at least one of A and B” and “at least one of A or B” may be construed to mean at least A, at least B, or at least A and B (i.e., a set comprising A and B, which set may include one or more additional elements). The term "A and/or B" may be construed to mean only A, only B, or both A and B.

[00169] The expressions “at least about A, B, and C” and “at least about A, B, or C” may be construed to mean at least about A, at least about B, or at least about C. The expressions “at most about A, B, and C” and “at most about A, B, or C” may be construed to mean at most about A, at most about B, or at most about C.

[00170] The expression “between about A and B, C and D, and E and F” may be construed to mean between about A and about B, between about C and about D, and between about E and about F. The expression “between about A and B, C and D, or E and F” may be construed to mean between about A and about B, between about C and about D, or between about E and about F.

[00171] The expression “about A to B and C to D” may be construed to mean between about A and about B and between about C and about D. The expression “about A to B or C to D” may be construed to mean between about A and about B or between about C and about D.

[00172] The terms “decompose,” “dissociate,” “reform,” “crack,” and “break down,” and their grammatical variations, may be construed interchangeably. For example, the expression “decomposition of ammonia” may be interchangeable with “dissociation of ammonia,” “reforming of ammonia,” “cracking of ammonia,” etc.

[00173] The terms “ammonia conversion,” “ammonia conversion rate,” and “ammonia conversion efficiency,” and their grammatical variations, may be construed as a fraction of ammonia that is converted to hydrogen and nitrogen, and may be construed interchangeably. For example, “an ammonia conversion efficiency of 90%” may represent 90% of ammonia being converted to hydrogen and nitrogen. The term “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction (2NH3 — > N2 + SEE; an endothermic reaction) is heated by a hydrogen combustion reaction (2H2 + O2 — > 2H2O; an exothermic reaction) using at least part of the hydrogen produced by the ammonia decomposition reaction itself.

[00174] In some cases, the term “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction is heated by a hydrogen combustion reaction using at least part of hydrogen produced by the ammonia decomposition reaction itself, electrical heating, or a combination of both (which may result in an overall positive electrical and/or chemical energy output). For example, if “auto-thermal reforming” is performed using a hydrogen combustion reaction and/or electrical heating, the hydrogen produced from the ammonia decomposition reaction may be enough to provide the hydrogen combustion reaction with combustion fuel, and/or to provide electrical energy for the electrical heating via hydrogen-to- electricity conversion devices (e.g., fuel cell, combustion engine, etc.).

[00175] In some cases, the hydrogen provided for the hydrogen combustion reaction and/or the electrical heating may or may not use the hydrogen from the ammonia decomposition reaction (for example, the hydrogen may be provided by a separate hydrogen source, the electricity may be provided from batteries or a grid, etc.).

[00176] In some cases, “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction is heated by a combustion reaction (e.g., ammonia combustion, hydrocarbon combustion, etc.), electrical heating, or a combination of both, which may result in an overall positive electrical and/or chemical energy output. For example, if “autothermal reforming” is performed using a combustion reaction and/or electrical heating, the chemical energy (e.g., lower heating value) from the hydrogen produced from the ammonia decomposition reaction may be higher than the combustion fuel chemical energy (e.g., lower heating value), and/or may be enough to provide electrical energy for the electrical heating via hydrogen-to-electricity conversion devices (e.g., fuel cell, combustion engine, etc.).

Ammonia Reforming System

[00177] FIGS. 1A-4B are block diagrams illustrating an ammonia reforming system 100, in accordance with one or more embodiments of the present disclosure. The ammonia reforming system 100 comprises an NH3 storage tank 102, a heat exchanger 106, one or more combustion- heated reformers 108, a combustion heater 109, one or more electrically-heated reformers 110, an electric heater 111, an air supply unit 116, an ammonia filter 122, and a fuel cell 124.

[00178] The NH3 storage tank 102 may be configured to store NH3 under pressure (e.g., 7- 9 bars absolute) and/or at a low temperature (e.g., -30 °C). The NH3 storage tank 102 may comprise a metallic material that is resistant to corrosion by ammonia (e.g., steel). The storage tank 102 may comprise one or more insulating layers (e.g., perlite or glass wool). In some cases, an additional heater may be positioned near, adjacent, at, or inside the NH3 storage tank 102 to heat and/or pressurize the NH3 stored therein.

[00179] The heat exchanger 106 may be configured to exchange heat between various input fluid streams and output fluid streams. For example, the heat exchanger 106 may be configured to exchange heat between an incoming ammonia stream 104 provided by the storage tank 102 (e.g., relatively cold liquid ammonia) and a reformate stream 120 (e.g., a relatively warm H2/N2 mixture) provided by the reformers 108 and 110. The heat exchanger 106 may be a plate heat exchanger, a shell-and-tube heat exchanger, or a tube-in-tube heat exchanger, although the present disclosure is not limited thereto.

[00180] The reformers 108 and 110 may be configured to generate and output the reformate stream 120 comprising at least a mixture of hydrogen (H2) and nitrogen (N2) (with a molar ratio of H2 to N2 of about 3: 1 at a high ammonia conversion). The H2/N2 mixture may be generated by contacting the incoming ammonia stream 104 with NH3 reforming catalyst 130 positioned inside each of the reformers 108 and 110. The reformers 108 and 110 may be heated to a sufficient temperature range to facilitate ammonia reforming (for example, of from about 400 °C to about 650 °C).

[00181] In some embodiments, the reformers 108 and 110 may comprise a plurality of reformers, which may fluidically communicate in various series and/or parallel arrangements. For example, an electrically-heated reformer 110 may fluidically communicate in series or in parallel with a combustion-heated reformer 108 (or vice versa) as a pair of reformers 108-110. Such a pair of reformers 108-110 may fluidically communicate in parallel with other reformer 108-110 or pairs of reformers 108-110 (so that pairs of reformers 108-110 combine their outputs into a single reformate stream 120), or may fluidically communicate in series with other reformer 108-110 or pairs of reformers 108-110.

[00182] In some instances, the number of combustion-heated reformers 108 may be the same as the number of electrically-heated reformers 110 , and the reformers 108-110 may fluidically communicate in various series and/or parallel arrangements. For example, two electrically-heated reformers 110 may fluidically communicate in series with two combustion- heated reformers 108 (or vice versa).

[00183] In some cases, the number of combustion-heated reformers 108 may be different from the number of electrically-heated reformers 110 and the reformers 108-110 may fluidically communicate in various series and/or parallel arrangements. For example, two electrically- heated reformers 110 may fluidically communicate in series with four combustion-heated reformers 108 (or vice versa).

[00184] The combustion heater 109 may be in thermal communication with the combustion-heated reformer 108 to heat the NH3 reforming catalyst 130 in the reformer 108. The combustion heater 109 may react at least part of the reformate stream 120 (e.g., the H2 in the H2/N2 mixture) with an air stream 118 (e.g., at least oxygen [O2]). The heat from the exothermic combustion reaction in the combustion heater 109 may be transferred to the NH3 reforming catalyst 130 in the reformer 108. For example, the hot combustion product gas 114 may contact walls of the reformer 108, and the hot combustion product gas 114 may be subsequently output from the combustion heater 109 as combustion exhaust 114. The combustion heater 109 may comprise a separate component from the reformer 108 (and may be slidably insertable or removable in the reformer 108). In some embodiments, the combustion heater 109 is a unitary structure with the combustion-heated reformer 108 (and both the reformer 108 and the heater 109 may be manufactured via 3D printing and/or casting).

[00185] The air supply unit 116 (e.g., one or more pumps and/or compressors) may be configured to supply the air stream 118 (which may be sourced from the atmosphere, and may comprise at least about 20% oxygen by molar fraction). The air stream 118 may comprise pure oxygen by molar fraction, or substantially pure oxygen by molar fraction (e.g., at least about 99% pure oxygen).

[00186] The electric heater 111 may be in thermal communication with the electrically- heated reformer 110 to heat the NH3 reforming catalyst 130 in the reformer 110. The electric heater 111 may heat the NH3 reforming catalyst 130 in the electrically-heated reformer 110 by resistive heating or Joule heating. In some instances, the electrical heater 111 may comprise at least a heating element (e.g., nichrome or ceramic) that transfers heat to the catalyst 130 in the electrically-heated reformer 110. In some cases, the electrical heater may comprise metal electrodes (e.g., copper or steel electrodes) that pass a current through the catalyst 130 to heat the catalyst 130 in the reformer 110.

[00187] The ammonia filter 122 may be configured to filter or remove trace ammonia in the reformate stream 120. The ammonia filter 122 may be configured to reduce the concentration of NH3 in the reformate stream 120, for example, from greater than about 10,000 parts per million (ppm) to less than about 100 ppm. The ammonia filter 122 may comprise a fluidized bed comprising a plurality of particles or pellets. The ammonia filter 122 may be cartridge-based (for simple replaceability, for example, after the ammonia filter 122 is saturated with ammonia).

[00188] The ammonia filter 122 may comprise an adsorbent (e.g., bentonite, zeolite, clay,

- l- biochar, activated carbon, silica gel, metal organic frameworks (MOFs), and other nanostructured materials). The adsorbent may comprise pellets, and may be stored in one or more columns or towers. Additionally or alternatively, the ammonia filter 122 may comprise an absorbent, a solvent-based material, and/or a chemical solvent.

[00189] In some embodiments, the ammonia filter 122 comprises a multi-stage ammonia filtration system (e.g., water-based) comprising a plurality of filtration stages. The replacement of water-based absorbents may be performed for continuous operation.

[00190] In some instances, the ammonia filter 122 comprises a selective ammonia oxidation (SAO) reformer including oxidation catalysts configured to react the trace ammonia in the reformate stream 120 with oxygen (O2) to generate nitrogen (N2) and water (H2O). The air stream 118 (or a separate oxygen source) may be provided to the SAO reformer to provide the oxygen for the oxidation reaction.

[00191] In some cases, the ammonia filter 122 may comprise an acidic ammonia remover (for example, additionally or alternatively to adsorbents), which may include an acidic solid or solution. The acidic ammonia remover may be regenerated (to desorb the ammonia captured therein) by passing an electric current through the acidic ammonia remover.

[00192] The fuel cell 124 may comprise an anode, a cathode, and an electrolyte between the anode and the cathode. The fuel cell 124 may comprise a polymer electrolyte membrane fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), a phosphoric acid fuel cell (PAFC), or an alkaline fuel cell (AFC), although the present disclosure is not limited thereto. The fuel cell 124 may process the EE in the reformate stream 120 at an anode and process the O2 in the air stream at a cathode to generate electricity (to power an external electrical load). The fuel cell 124 may be configured to receive hydrogen (e.g., at least part of the reformate stream 120) via one or more anode inlets, and oxygen (e.g., at least part of the air stream 118 or a separate air stream) via one or more cathode inlets.

[00193] In some embodiments, the fuel cell 124 may output unconsumed hydrogen (e.g., as an anode off-gas) via one or more anode outlets, and/or may output unconsumed oxygen (e.g., as a cathode off-gas) via one or more cathode outlets. The anode off-gas and/or the cathode offgas may be provided to the combustion heater 109 as reactants for the combustion reaction performed therein.

[00194] As shown in FIGS. 1A-1B, the storage tank 102 may be in fluid communication with the combustion-heated reformer 108 and/or the electrically-heated reformer 110 (e.g., using one or more lines or conduits). The storage tank 102 may provide the incoming ammonia stream 104 (for example, by actuating a valve). The heat exchanger 106 may facilitate heat transfer from the (relatively warmer) reformate stream 120 to the (relatively cooler) incoming ammonia stream 104 to vaporize the incoming ammonia stream 104 (changing the phase of the ammonia stream 104 from liquid to gas). The gaseous incoming ammonia stream 104 may then enter the reformers 108 and 110 to be reformed into hydrogen and nitrogen.

[00195] In some instances, the gaseous incoming ammonia stream 104 may first be partially reformed by the electrically-heated reformer 110 into a partially cracked reformate stream 120 (e.g., comprising at least about 10% H2/N2 mixture by molar fraction) (for example, during a start-up or initiation process). Subsequently, the partially cracked reformate stream 120 may be further reformed in the combustion-heated reformer 108 to generate a substantially cracked reformate stream (e.g., comprising less than about 10,000 ppm of residual or trace ammonia by volume and/or greater than about 99% H2/N2 mixture by molar fraction). Passing the ammonia stream 104 through the electrically-heated reformer 110 first, and then subsequently passing the ammonia stream 104 through the combustion-heated reformer 108, may advantageously result in more complete ammonia conversion (e.g., greater than about 99%). [00196] In some cases, the incoming ammonia stream 104 may first be partially reformed by the combustion-heated reformer 108 into a partially cracked reformate stream 120 (e.g., comprising at least 10% H2/N2 mixture by molar fraction). Subsequently, the partially cracked reformate stream 120 may be further reformed in the electrically-heated reformer 110 to generate a substantially cracked reformate stream (e.g., comprising less than about 10,000 ppm of residual or trace ammonia by volume and/or greater than about 99% H2/N2 mixture by molar fraction).

Passing the ammonia stream 104 through the combustion-heated reformer 108 first, and then subsequently passing the ammonia stream 110 through the electrically-heated reformer 108, may advantageously result in more complete ammonia conversion (e.g., greater than about 99%). [00197] In some embodiments, the incoming ammonia stream 104 may first be preheated by the combustion exhaust 114 and/or the combustion heater 109. In some instances, the preheated incoming ammonia stream 104 may then enter the reformers 108 and 110 to be reformed into hydrogen and nitrogen

[00198] In some cases, the gaseous incoming ammonia stream 104 may first be reformed by the electrically-heated reformer 110 to generate a partially or substantially cracked reformate stream 120 (for example, during a start-up or initiation process). Subsequently, at least part of the partially or substantially cracked reformate stream 120 generated by the electrically-heated reformer 110 may be combusted as a combustion fuel to heat at least one combustion heater 109 of the one or more combustion-heated reformers 108. [00199] In some embodiments, power input to the electric heater 111 of the electrically- heated reformer 110 may be reduced or entirely turned off based on a temperature of the combustion-heated reformer 108 and/or the combustion heater 109 being equal to or greater than a target temperature (e.g., in a target temperature range). In some instances, power input to the electric heater 111 of the electrically-heated reformer 110 may be reduced or entirely turned off based on a flow rate of the incoming ammonia stream 104 being equal to or greater than a target flow rate range.

[00200] As shown in FIG. 2, the ammonia filter 122 may be configured to remove trace ammonia in the reformate stream 120 and output a filtered reformate stream 123. The filtered reformate stream 123 may then be provided to the combustion heater 109 to combust for heating the reformer 108 (i.e., by auto-thermal reforming).

[00201] As shown in FIG. 3, the filtered reformate stream 123 may be provided to the fuel cell 124 to generate electrical power 126. An external load (e.g., an electrical motor to power a transport vehicle, or a stationary electrical grid) may utilize the electrical power 126. The fuel cell 124 may provide the anode off-gas 128 (e.g., containing unconsumed or unconverted hydrogen) to the combustion heater 109 to combust for self-heating.

[00202] In some embodiments, the ammonia reforming system 100 includes a battery (so that the system 100 is a hybrid fuel cell-battery system). The battery may be configured to power an external load in addition to the fuel cell 124. The fuel cell 124 may be configured to charge the battery (for example, based a charge of the battery being less than a threshold charge). [00203] As shown in FIG. 4A, a pressure swing adsorber (PSA) 127 may be configured to adsorb NH3 and/or N2 in the filtered reformate stream 123 (or the reformate stream 120) to further purify the filtered reformate stream 123. The PSA may be configured to increase the molar fraction of H2 in the filtered reformate stream 123 (or the reformate stream 120), and decrease the molar fractions of NH3 and/or N2 in the filtered reformate stream 123 (or the reformate stream 120). A PSA exhaust stream 128 comprising H2 (and which may additionally comprise NH3 and/or N2) may then be provided to the combustion heater 109 to combust for self-heating the reformer 108 (i.e., by auto-thermal reforming). Additionally, a purified reformate stream 129 may be provided to the fuel cell 124 to generate the electrical power output 126.

[00204] As shown in FIG. 4B, a flow distributor 115 may be configured to distribute at least portion of the reformate stream 120 (or the filtered reformate stream 123) to the combustion heater 109 as a combustion fuel. The flow distributor 130 may comprise, for example, one or more valves, pumps, or flow regulators. A remaining reformate stream 117 may be provided to various chemical or industrial processes, including, but not limited to, steel or iron processing, combustion engines, combustion turbines, hydrogen storage, hydrogen for chemical processes, hydrogen fueling stations, etc. In some cases, the remaining reformate stream 117 can be supplied as a pilot, auxiliary, or main fuel to the combustion engines or combustion turbines.

[00205] In some cases, the reformate stream 120, the filtered reformate stream 123, the purified reformate stream 129, and/or the remaining reformate stream 117 may be provided to an internal combustion engine (ICE). Heat emitted by the ICE may be used to heat the reformer 108 and/or the reformer 110 (e.g., using a heat exchanger).

[00206] In some instances, the reformate stream 120, the filtered reformate stream 123, the purified reformate stream 129, and/or the remaining reformate stream 117 may be used directly for chemical or industrial processes (e.g., to reduce iron), storage (e.g., hydrogen storage), and/or hydrogen fueling stations.

[00207] In any of embodiments and/or configurations described with respect to FIGS. 1A- 4B, the fuel cell 124 may be absent, and at least part of the reformate 120 may be combusted to maintain an auto-thermal reforming process. The remaining reformate 120 (that is not combusted) may be provided for chemical or industrial processes, storage (e.g., hydrogen storage), and/or hydrogen fueling stations. In some cases, the remaining reformate stream 120 is provided to an ICE. In some cases, heat emitted by the ICE may provide at least part or all of the heat required for ammonia reforming in the reformer 108 and/or the reformer 110. Any of the embodiments, configurations and/or components described with respect to FIGS. 1A-4B, may be partially or entirely powered by exhaust heat from a combustion engine.

Combustion-Heated Reformer

[00208] FIG. 5 is a schematic diagram illustrating the combustion-heated reformer 108 including the combustion heater 109, in accordance with one or more embodiments of the present disclosure.

[00209] The combustion-heated reformer 108 may comprise one or more cylindrical sections positioned annularly with respect to a central longitudinal axis 131. For example, the reformer 108 may comprise an inner shell 132 and an outer shell 133. The inner shell 132 and the outer shell 133 may include one or more cavities therein, and NH3 reforming catalyst 130 may be positioned in the cavities. The inner shell 132 and the outer shell 133 may be in fluid communication, for example, via one or more U-turn sections (e.g., gap[s] in the wall separating the inner shell 132 and the outer shell 133).

[00210] In some embodiments, the incoming NH3 stream 104 may first pass through the inner shell 132 via an inlet, subsequently pass through the outer shell 133, and exit the combustion-heated reformer 108 via an outlet (e.g., as a partially or substantially cracked reformate stream 120). In some cases, the incoming NH3 stream 104 may first pass through the outer shell 133 via an inlet, subsequently pass through the inner shell 132, and exit the combustion-heated reformer 108 via an outlet (e.g., as a partially or substantially cracked reformate stream 120).

[00211] The combustion heater 109 may include a flame tube 109a and a burner head 134. The flame tube 109a may be slidably insertable and removable from the reformer 108 (and thus may be simple to replace in the event of a defect or malfunction). The inner shell 132, the outer shell 133, and the flame tube 109a may be concentrically aligned along a longitudinal axis 131 so that the inner shell 132 is adjacent to the flame tube 109a, and the outer shell 133 is adjacent to the inner shell 132. In some instances, the inner shell 132, the outer shell 133, and the flame tube 109a may not be concentrically aligned. The burner head 134 may be positioned at a first side of the flame tube 109a, and the combustion exhaust 114 (i.e., hot combustion product gas 114) may exit the flame tube 109a through an exhaust port at a second side of the flame tube 109a opposite to the first side.

[00212] The burner head 134 may include one or more inlets configured to receive at least part of the reformate stream 120 (or the filtered reformate stream 123, the purified reformate stream 129, the anode off-gas 128, or other gas stream that includes hydrogen) and the air stream 118. The burner head 134 may mix the at least part of the reformate stream 120 and the air stream 118 to form a reactant mixture, and provide or inject the reactant mixture into the flame tube 109a for the combustion reaction in the flame tube 109a. In some embodiments, the burner head 134 may inject at least part of the reformate stream 120 and the air stream 118 separately into the flame tube 109a for the combustion reaction in the flame tube 109a.

[00213] To initiate the combustion reaction, the reactant mixture may be ignited to generate a flame near the burner head 134 (using, for example, a spark plug or other ignition device). The flame temperature and topology may be controlled or tuned, for example, by adjusting the ratio of the reformate stream 120 to the air 118 (i.e., the fuel to air ratio).

[00214] As shown in FIG. 5, the incoming ammonia stream 104 may enter the reformer 108 and pass the catalyst-filled inner shell 132 and the catalyst-filled outer shell 133 to be reformed into the reformate stream 120. By first passing the inner shell 132, and then subsequently passing the outer shell 133, the incoming ammonia stream may be substantially converted (e.g., about 99% converted) into an H2/N2 mixture.

[00215] In some cases, the incoming ammonia stream 104 may enter the reformer 108 and pass the catalyst-filled outer shell 133 and the catalyst-filled inner shell 132 to be reformed into the reformate stream 120. By first passing the outer shell 133, and then subsequently passing the inner shell 132, the incoming ammonia stream may be substantially converted (e.g., 99% converted) into an H2/N2 mixture. In some cases, the ammonia conversion is at least about 70, 80, 90, 95, or 99%. In some cases, the ammonia conversion is at most about 70, 80, 90, 95, 99, 99.5, or 99.9%. In some cases, the ammonia conversion is about 70 to 99.9, 80 to 99.5, 90 to 99, or 95 to 99.9%.

[00216] In some embodiments, the flame tube 109a, the inner shell 132, and the outer shell 133 each comprise a metal or a ceramic. For example, the metal may comprise steel, stainless steel, tungsten, titanium, and/or alloys thereof, and the ceramic may comprise alumina, silicon carbide, aluminum carbide, or combinations thereof, however the present disclosure is not limited to such materials.

[00217] In some instances, the flame tube 109a, the inner shell 132, and the outer shell 133 may each comprise a length ranging of from about 0.2 to 10, 1 to 9, 2.5 to 7.5, 3 to 7, or 4 to 6 meters. The flame tube 109a, the inner shell 132, and the outer shell 133 may each comprise a length of at least about 0.2, 0.4, 0.6, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 meters. The flame tube 109a, the inner shell 132, and the outer shell 133 may each comprise a length of at most about 0.2, 0.4, 0.6, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 meters. The flame tube 109a may be longer than the inner shell 132 and/or the outer shell 133.

[00218] In some cases, the walls of at least one of the flame tube 109a, the inner shell 132, and/or the outer shell 133 comprise a thickness of from about 1 mm to 5 mm, 3 mm to 10 mm, 1 cm to 5 cm, 1 mm to 10 cm, 1 cm to 10 cm, 2 cm to 8 cm, 3 cm to 7 cm, or 4 cm to 6 cm. The walls of at least one of the flame tube 109a, the inner shell 132, and the outer shell 133 may comprise a thickness of at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30 ,40, 50, 60, 70, 80, 90, or 100 mm. The walls of at least one of the flame tube 109a, the inner shell 132, and the outer shell 133 may comprise a thickness of at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30 ,40, 50, 60, 70, 80, 90, or 100 mm. The thicknesses may be selected to achieve a target temperature in the NH3 reforming catalyst 130 (e.g., a target temperature range of from about 400 °C to about 600 ⁰ C) by optimizing heat transfer from the hot combustion product gas 114 in the flame tube 109 to the NH3 reforming catalyst 130.

[00219] In some embodiments, a target temperature for reforming in the combustion- heated reformer 108 (and/or the electrically-heated reformer 110) is at least about 350, 400, 450, 500, 550, 600, 650, 700, 750, or 800 °C. The target temperature may be at most about 400, 450, 500, 550, 600, 650, 700, 750, or 800 °C. In some cases, the target temperature may be from about 350°C to 800°C, 400°C to 750°C, 450°C to 700°C, 500°C to 650°C, 450°C to 600°C, or 500°C to 550°C.

[00220] In some instances, an outer diameter of the inner shell 132 (with respect to the longitudinal axis 131) comprises 1.1 to 3 times an outer diameter of the flame tube 109a (with respect to the longitudinal axis 131), 0.5 to 3.5 times an outer diameter of the flame tube 109a, or about 0.1 to about 4 times an outer diameter of the flame tube 109a. The outer diameter of the inner shell 132 (with respect to the longitudinal axis 131) may comprise at least about 1.1, 1.5, 2, 2.5, or 3 times an outer diameter of the flame tube 109a (with respect to the longitudinal axis 131). The outer diameter of the inner shell 132 (with respect to the longitudinal axis 131) may comprise at most about 1.1, 1.5, 2, 2.5, or 3 times an outer diameter of the flame tube 109a (with respect to the longitudinal axis 131). The outer diameter of the inner shell 132 (with respect to the longitudinal axis) may comprise at least about 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.2,

2.4, 2.6, 2.8, or 3 times an outer diameter of the flame tube 109a. The outer diameter of the inner shell 132 (with respect to the longitudinal axis) may comprise at most about 1.1, 1.2, 1.3, 1.4,

1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.2, 2.4, 2.6, 2.8, or 3 times an outer diameter of the flame tube 109a. In some cases, the outer diameter of the inner shell 132 (with respect to the longitudinal axis) may be from about 1.1 times to 3 times, 1.2 times to 2.8 times, 1.3 times to 2.6 times, 1.4 times to 2.4 times, 1.5 times to 2.2 times, 1.6 times to 2 times, 1.1 times to 1.5 times, or 1.7 times to 1.8 times an outer diameter of the flame tube 109a.

[00221] In some cases, a ratio of a volume of the outer shell 133 to a volume of the inner shell 132 comprises of from about 1 : 1 to 5: 1, of from 0.5: 1 to 10: 1, or of from 0.1 : 1 to 20: 1. The ratio of a volume of the outer shell 133 to a volume of the inner shell 132 may be at least about 1 : 1, 2: 1, 3: 1, 4: 1, 5: 1, 6:1, 7: 1, 8: 1, 9: 1, 10: 1, or 20: 1. The ratio of a volume of the outer shell 133 to a volume of the inner shell 132 may be at most about 1 : 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, or 20: 1.

[00222] The NH3 reforming catalyst 130 may comprise a low-temperature catalyst configured to reform ammonia at relatively low temperatures (e.g., about 400 to about 500 °C) and/or a high-temperature catalyst configured to reform ammonia at relatively high temperatures (e.g., about 500 to about 700 °C). The low-temperature catalyst may comprise, for example, ruthenium (Ru) or platinum (Pt), and the high temperature catalyst may comprise, for example, nickel (Ni) or iron (Fe).

[00223] The low-temperature NH3 reforming catalyst may be positioned in a relatively low temperature region of the combustion-heated reformer 108 (e.g., outer shell 133). The high- temperature NH3 reforming catalyst may be positioned in a relatively high temperature region of the combustion-heated reformer 108 (e.g., inner shell 132).

Preheating Conduit for Preheating NH3

[00224] As shown in FIG. 6, a preheating conduit 137 may be positioned inside (and, in some embodiments, at the center of) the flame tube 109a of the combustion heater 109 (and/or the burner head 134). In some cases, the preheating conduit 137 may be concentrically aligned along the longitudinal axis 131 of the combustion heater 109. In some cases, the preheating conduit 137 is not concentrically aligned with the longitudinal axis 131 of the combustion heater 109. In some instances, a plurality of preheating conduits 137 may be positioned inside the flame tube 109a.

[00225] The preheating conduit 137 may be configured to transfer heat from the combustion product gas 114 in the flame tube 109a to the incoming ammonia stream 104 to further preheat and/or evaporate the ammonia stream 104 (thereby facilitating ammonia conversion into the reformate stream 120 by the catalyst 130 further downstream).

[00226] After being preheated in the preheating conduit 137, the ammonia stream 104 may exit the combustion-heated reformer 108 (for example, via an outlet at a top side of the reformer 108 as a partially or substantially cracked reformate stream 120), and subsequently may be provided to a different reformer (e.g., electrically-heated reformer 110), a heat exchanger, or directly to the catalyst-filled inner shell 132 or outer shell 133 of the combustion-heated reformer 108 for reforming.

[00227] In some embodiments, the preheating conduit 137 may be filled with NH3 reforming catalyst 130, for partial reforming of the incoming ammonia stream 104, and for cooling of the preheating conduit 137 via the endothermic NH3 reforming reaction.

[00228] The preheating conduit 137 may be cylindrical, and may comprise a metal or ceramic. In some cases, a diameter of the preheating conduit 137 is about 0.05 to about 0.9 times an inner diameter of the flame tube 109a. The diameter of the preheating conduit 137 may be at least about 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 times an inner diameter of the flame tube 109a. The diameter of the preheating conduit 137 may be at most about 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 times an inner diameter of the flame tube 109a. In some cases, the diameter of the preheating conduit 137 may be from about 0.05 times to 0.9 times, 0.1 times to 0.8 times, 0.2 times to 0.7 times, 0.3 times to 0.6 times, or 0.4 times to 0.5 times an inner diameter of the flame tube 109a.

[00229] In some instances, a length of the preheating conduit 137 is about 0.75 to about 2 times a length of the flame tube 109a. The length of the preheating conduit 137 may be at least about 0.75, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 times a length of the flame tube 109a. The length of the preheating conduit 137 may be at most about 0.75, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 times a length of the flame tube 109a. In some cases, the length of the preheating conduit 137 may be from about 0.75 times to 2 times, 0.8 times to 1.8 times, 0.9 times to 1.6 times, 1 times to 1.4 times, or 1.2 times to 2 times a length of the flame tube 109a. In some embodiments, the preheating conduit 137 comprises a straight tube shape, a helical (e.g., spiral) shape, a curved shape, a U shape, a V shape, and/or a W shape. In some cases, the preheating conduit 137 is unitary with the flame tube 109a (e.g., both components may be manufactured by 3D printing and/or casting).

[00230] In some instances, the incoming ammonia stream 104 may flow in the preheating conduit 137 in an opposite direction from the direction shown in FIG. 6, so that the incoming ammonia stream 104 enters the conduit 137 from a side of the combustion heater 109 that is opposite to the burner head 134, and exits the conduit 137 at a side of the combustion heater 109 that is adjacent or near the burner head 134.

Preheating Conduit for Preheating Air

[00231] As shown in FIG. 7, the preheating conduit 137 may be configured to transfer heat from the combustion product gas 114 in the flame tube 109a to the air stream 118 (e.g., supplied by the air supply unit 116) to preheat the air stream 118 (which facilitates combustion in the flame tube 109a by reducing the amount of combustion fuel required for combustion). After passing the conduit 137 and being preheated, the air stream 118 may enter the flame tube 109a via the burner head 134 as an oxidation reactant for the combustion reaction.

[00232] It is noted that FIG. 7 illustrates an advantageous counter-current or counter-flow configuration, where the hot combustion product gas 114 in the flame tube 109a travels in a direction opposite to the direction of travel of the air stream 118 in the preheating conduit 137. This configuration may facilitate heat transfer, for example, in comparison to a parallel-flow configuration.

Preheating Conduit with Injection Holes

[00233] As shown in FIG. 8, the preheating conduit 137 may comprise a plurality of injection holes 138a-f (or apertures, slots, slits, etc.) positioned along the length of the preheating conduit 137 (i.e., along the longitudinal axis 131). The plurality of injection holes 138a-f may be positioned at or in curved walls (i.e., circumference) of the preheating conduit 137. The plurality of injection holes 138a-f may be configured to inject the air 118 into the flame tube 109a in a staged injection pattern.

[00234] The plurality of injection holes 138a-f may be variably sized along the length of the preheating conduit 137 and/or the flame tube 109a to enable different injection velocities of the air 118 into the flame tube 109a. For example, the injection hole 138f may be smaller in size than the injection holes 138a-e. In some cases, the injection hole 138a may be smaller in size than the injection holes 138b-f. In some cases, the plurality of injection holes 138a-f may be relatively larger in a first region of the preheating conduit 137 and relatively smaller in a second region of the preheating conduit 137.

[00235] In some cases, the plurality of injection holes 138a-f are angled (e.g., about 5° to about 90° with respect to a plane that is normal to the longitudinal axis 131 of the combustion heater 109a) to improve mixing of the oxygen (from the air stream 118) and the hydrogen (from the reformate stream 120). In some cases, the plurality of injection holes 138a-f are positioned so that the air 118 is injected tangentially into the combustion heater 109 with respect to the curved wall (circumference) of the preheating conduit 137 (to swirl the air 118 and improve mixing of O2 and H2). In some cases, the plurality of injection holes 138a-f may be positioned so that the air 118 is injected normally (i.e., perpendicular) into the combustion heater 109 with respect to the curved wall (circumference) of the preheating conduit 137.

[00236] It is noted that, in some instances, the staged injection enabled by the injection holes 138a-f may advantageously result in fuel-rich and fuel-lean combustion occurring in different regions of the flame tube 109a. In some cases, the staged injection enabled by the injection holes 138a-f may advantageously result in a uniform combustion reaction (so that heat is distributed uniformly to the catalyst 130 in the reformer 108). Although six injection holes 138a-f are shown in FIG. 8, it is contemplated that the flame tube 109a may comprise any number of injection holes 138.

Electrically-heated Reformer

[00237] FIGS. 9A-9C are schematic diagrams illustrating the electrically-heated reformer 110 in fluid communication with the combustion-heated reformer 108, in accordance with one or more embodiments of the present disclosure.

[00238] As shown in FIG. 9A, the electrically-heated reformer 110 may comprise one or more cylindrical sections positioned annularly with respect to a central longitudinal axis 139 of the electrically-heated reformer 110. For example, the reformer 110 may comprise an inner shell 142 and an outer shell 143. The inner shell 142 and the outer shell 143 may include one or more cavities therein, and NH3 reforming catalyst 130 may be positioned in the cavities. The inner shell 142 and the outer shell 143 may be in fluid communication, for example, via one or more U-turn sections (e.g., gap[s] in the wall separating the inner shell 142 and the outer shell 143).

[00239] In some embodiments, the inner shell 142, the outer shell 143, and the electrical heater 111 may be concentrically aligned along the longitudinal axis 139 so that the inner shell 142 is adjacent to the electrical heater 111, and the outer shell 143 is adjacent to the inner shell 142. In some cases, the inner shell 142, the outer shell 143, and the electrical heater 111 may not be concentrically aligned. The electrical heater 111 may be slidably insertable and removable in the reformer 111 (which may facilitate replacement in the event of a defect or malfunction).

[00240] In some instances, the incoming NH3 stream 104 may first pass through the inner shell 142 via an inlet, subsequently pass through the outer shell 143, and exit the electrically- heated reformer 110 via an outlet (as a partially or substantially cracked reformate stream 120). In some embodiments, the incoming NH3 stream 104 may first pass through the outer shell 143 via an inlet, subsequently pass through the inner shell 142, and exit the electrically-heated reformer 110 via an outlet (as a partially or substantially cracked reformate stream 120).

[00241] As shown in FIG. 9A, the preheating conduit 137, the electrically-heated reformer 110, and the combustion-heated reformer 108 may be in fluid communication, and configured so that the incoming ammonia stream 104 first passes the preheating conduit 137 (to be preheated), then subsequently passes the NH3 reforming catalyst 130 of the electrically-heated reformer 110 (to be reformed), and then subsequently passes the NH3 reforming catalyst 130 of the combustion-heated reformer 108 (to be substantially or completely reformed). The configuration shown in FIG. 9A may provide fuel to quickly initiate ammonia reforming, and may increase ammonia conversion efficiency (compared to using the combustion-heated reformer 108 alone).

[00242] In some cases, the NH3 reforming catalyst 130 in the electrically-heated reformer 110 may comprise a low-temperature catalyst configured to reform ammonia at relatively low temperatures (e.g., about 400 to about 500 °C) and/or a high-temperature catalyst configured to reform ammonia at relatively high temperatures (e.g., about 500 to about 700 °C). In some instances, the low-temperature catalyst may comprise, for example, ruthenium (Ru) or platinum (Pt), and the high temperature catalyst may comprise, for example, nickel (Ni) or iron (Fe).

[00243] In some embodiments, the low-temperature NH3 reforming catalyst may be positioned in a relatively low temperature region of the combustion-heated reformer 108 (e.g., outer shell 133). In some cases, the high-temperature NH3 reforming catalyst may be positioned in a relatively high temperature region of the combustion-heated reformer 108 (e.g., inner shell 132). [00244] As shown in FIG. 9B, the incoming ammonia stream 104 may first pass the preheating conduit 137 in the combustion heater 109 (to be preheated), then subsequently pass the NH reforming catalyst 130 of the combustion-heated reformer 108 (to be reformed), and then subsequently pass the NH3 reforming catalyst 130 of the electrically-heated reformer 110 (to be substantially or completely reformed).

[00245] As shown in FIG. 9C, the incoming ammonia stream 104 may first pass the NH3 reforming catalyst 130 of the electrically-heated reformer 110 (to be reformed), and then subsequently pass the NH3 reforming catalyst 130 of the combustion-heated reformer 108 (to be substantially or completely reformed).

Heat Exchanger

[00246] FIGS. 10-12 are schematic diagrams illustrating a heat exchanger 140 in addition to the combustion-heated reformer 108 shown in FIG. 5, in accordance with one or more embodiments of the present disclosure. The heat exchanger 140 may facilitate heat exchange between various components of the reforming system 100. In some instances, the heat exchanger 140 may comprise the heat exchanger 106 described with respect to FIGS. 1A-4B.

[00247] As shown in FIG. 10, the heat exchanger 140 may be configured to exchange heat between the (relatively warm) reformate stream 120 and the (relatively cool) incoming ammonia stream 104 (to preheat and/or vaporize the incoming ammonia stream 104 to facilitate NH3 reforming). The reformate stream 120 may exit the heat exchanger 140 at a lower temperature (compared to the relatively warmer temperature of the reformate stream 120 before entering the heat exchanger 140), which may be advantageous since a high temperature of the reformate stream 120 may reduce hydrogen consumption and/or efficiency at the fuel cell 124. In the configuration shown in FIG. 10, the preheated ammonia stream 104 is provided to the preheating conduit 137 to be heated further by the hot combustion product gas 114 in the flame tube 109a.

[00248] As shown in FIG. 11, the heat exchanger 140 may be configured to exchange heat between the (relatively warm) combustion product gas 114 and the (relatively cool) incoming ammonia stream 104 (to preheat and/or vaporize the incoming ammonia stream 104, thereby facilitating NH3 reforming). In some cases, to facilitate combustion in the combustion heater 109, instead of preheating the ammonia stream 104, the heat exchanger 140 may be configured to preheat the combustion reactants (e.g., oxygen or hydrogen) by exchanging heat between the air 118 (and/or at least part of the reformate 120) and the hot combustion product gas 114. [00249] As shown in FIG. 12, the heat exchanger 140 may be configured to exchange heat between the (relatively warm) reformate stream 120 and the (relatively cool) air stream 118 (to preheat the air stream 118 to improve efficiency and lower the fuel requirement for combustion in the combustion heater 109). In some embodiments, the heat exchanger 140 may preheat the anode off-gas 503 (emitted by the fuel cell 124), before the anode off-gas 502 is provided as combustion fuel to the combustion heater 109.

[00250] It is noted that any of the configurations of the heat exchanger 140 described in the present disclosure may comprise a counter-flow configuration, a cross-flow configuration, or a parallel-flow configuration.

[00251] Although various configurations of the heat exchanger 140 are described, it is noted that the configurations of the heat exchanger 140 are not limited thereto. For example, in some instances, one or more heat exchangers 140 may exchange heat between one or more incoming ammonia streams 104 and: (1) one or more reformate streams 120, (2) one or more combustion heaters 109, (3) one or more combustion exhausts 114, (4) one or more ammonia filters 122, (5) one or more fuel cells 124, and/or (6) one or more air streams 118. Preheating the one or more ammonia streams 104 may facilitate NH3 reforming (by increasing ammonia conversion efficiency).

[00252] In some cases, one or more heat exchangers 140 are configured to exchange heat between one or more reformate streams 120 and: (1) one or more air streams 119, and/or (2) one or more ammonia filters 122.

[00253] In some embodiments, one or more heat exchangers 140 are configured to exchange heat between one or more ammonia filters 122 and: (1) one or more combustion-heated reformers 108, (2) one or more combustion heaters 109, (3) one or more electrically-heated reformers 110, (4) one or more electrical heaters 111, (5) one or more combustion exhausts 114, and/or (6) one or more reformate streams 120. Heating the one or more ammonia filters 122 may regenerate the one or more ammonia filters 122 by releasing adsorbed ammonia. The ammonia released from the one or more ammonia filters 122 may be combusted in the one or more combustion heaters 109, filtered by one or more ammonia scrubbers, dissolved or mixed in water, or vented to the atmosphere.

[00254] In some instances, one or more heat exchangers 140 are configured to exchange heat between one or more air streams 118 and: (1) one or more combustion heaters 109, (2) one or more electrical heaters 111, (3) one or more reformate streams 120, and/or (4) one or more fuel cells 124. Preheating the one or more air streams 118 may facilitate combustion efficiency and reduce the amount of fuel required for combustion. [00255] In some cases, one or more heat exchangers 140 are configured to exchange heat between one or more NH3 storage tanks 102 and: (1) one or more combustion heaters 109, (2) one or more electrical heaters 111, (3) one or more additional electrical heaters for heating the NH3 storage tanks 102, (4) one or more combustion exhausts 114, (5) one or more reformate streams 120, (6) ambient air, (7) one or more air streams 118, and/or (8) one or more fuel cells 124. Preheating the storage tank 102 may evaporate the NH3 stored therein, or increase a pressure of the NH3 stored therein, which may facilitate ammonia reforming further downstream (e.g., by increasing ammonia conversion efficiency).

[00256] In some embodiments, one or more heat exchangers 140 are configured to exchange heat between one or more one or more combustion heaters 109 and: (1) one or more incoming ammonia streams 104, and/or (2) one or more air streams 118. Cooling the one or more combustion heaters 109 may prevent damage from overheating (e.g., fractures from thermal stress).

[00257] In some instances, one or more heat exchangers 140 are configured to exchange heat between one or more fuel cells 124 and: (1) one or more incoming ammonia streams 104, (2) one or more air streams 118, and/or (3) ambient air. Cooling the one or more fuel cells 124 may advantageously increase the hydrogen utilization rate, fuel cell efficiency, or the output voltage of the one or more fuel cells 124. The one or more heat exchangers 140 may be configured to exchange heat from the one or more fuel cells 124 using an intermediate fluid, e.g., a coolant such as a glycol, water, etc.

[00258] In some cases, any of the heat exchanger configurations described herein may use one or more intermediate fluids (e.g., a coolant such as a glycol, water, etc.) to transfer heat.

Bluff Body with Heat Exchanging Conduits

[00259] FIGS. 13-15 are schematic diagrams illustrating a bluff body 143 positioned inside the combustion heater 109 shown in FIG. 5, in accordance with one or more embodiments of the present disclosure. The bluff body 143 may be positioned in a bluff body portion 141 of the combustion heater 109 between a catalyst-sleeve portion 142 (adjacent to the NH3 reforming catalyst 130 in the inner shell 132 of the combustion-heated reformer 108) and the burner head 134.

[00260] The bluff body 143 may be configured to absorb heat from the hot combustion product gas 114 in the combustion heater 109 (e.g., emitted by a flame near the burner head 134), thereby cooling the hot combustion product gas 114 before the product gas 114 reaches the catalyst-sleeve portion 142. This cooling minimizes durability issues related to thermal stress (for example, by reducing the probability of fractures in the walls of the combustion heater 109 or the reformer 108).

[00261] The bluff body 143 may comprise a metal or ceramic. The shape of the bluff body 143 may be selected or tuned to control the flow field in the combustion heater 109 (to improve mixing and reduce NO_X emissions). A shape of a cross-section of the bluff body 143 may comprise a circle, an ellipse, a square, a diamond, a triangle, a polygon, or any combination thereof. In some cases, different cross-sections of the bluff body 143 may comprise the same shape, or different shapes.

[00262] In some embodiments, a width of the bluff body 143 may comprise of from about 0.1 - about 0.95 times an outer diameter of the flame tube 109a. The width of the bluff body 143 may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times an outer diameter of the flame tube 109a. The width of the bluff body 143 may be at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times an outer diameter of the flame tube 109a of the combustion heater 109. In some cases, the width of the bluff body 143 is from about 0.1 times to 0.95 times, 0.2 times to 0.9 times, 0.3 times to 0.8 times, 0.4 times to 0.7 times, or 0.5 times to 0.6 times an outer diameter of the flame tube 109a of the combustion heater 109.

[00263] In some instances, a length of the bluff body 143 may comprise of from 0.05 to 0.5 times a length of a flame tube 109a. A length of the bluff body 143 may comprise at least about 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5 times a length of a flame tube 109a. The length of the bluff body 143 may comprise at most about 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5 times a length of the flame tube 109a. In some cases, the length of the bluff body 143 may be from about 0.05 times to 0.5 times, 0.1 times to 0.4 times, or 0.2 times to 0.3 times a length of the flame tube 109a.

[00264] As shown in FIG. 13, the bluff body 143 may be configured to preheat one or more incoming streams (e.g., the incoming ammonia stream 104, the incoming air stream 118, etc.) using heat exchanging conduits 144. For example, the bluff body 143 may be configured to receive the ammonia stream 104 via inlets (e.g., positioned partially at or in the walls of the combustion heater 109), and the ammonia stream 104 may pass through the bluff body 143 via the heat exchanging conduits 144 in the bluff body 143.

[00265] The heat exchanging conduits 144 may comprise a helical (e.g., spiral) shape, a straight shape, a serpentine shape, or may comprise other curved shapes or topologies. Heat generated from the flame adjacent to the burner head 134 (near an inlet side of the combustion heater 109) may heat the bluff body 143, and heat the incoming ammonia stream 104 passing through the heat exchanging conduits 144 of the bluff body 143. In some cases, the heat exchanging conduits 144 of the bluff body 143 may include NH3 reforming catalyst therein to pre-reform the ammonia stream 104. By preheating and pre-reforming the ammonia stream 104, the heat exchanging conduits 144 of the bluff body 143 may advantageously increase overall ammonia conversion efficiency.

[00266] After exiting the bluff body 143, the incoming ammonia stream 104 may then pass through the preheating conduit 137 for further preheating. The heat exchanging conduits 144 of the bluff body 143 may be in fluid communication with the preheating conduit 137 (described in detail with respect to FIGS. 7 - 9). The preheating conduit 137 and the bluff body 143 may be concentrically aligned along the longitudinal axis 131 of the combustion heater 109. In some embodiments, the preheating conduit 137 and the bluff body 143 are not concentrically aligned along the longitudinal axis 131 of the combustion heater 109.

Sidewalls for Preheating NH3

[00267] As shown in FIG. 14, at least a portion of the combustion heater 109 may comprise hollow sidewalls 145 including a cavity configured to receive the incoming ammonia stream 104 from the storage tank 102 to preheat the incoming ammonia stream 104. The hollow sidewalls 145 may be positioned adjacent to the burner head 134 to absorb heat from the flame of the combustion reaction in the flame tube 109a (thereby minimizing thermal stress and durability issues in the flame tube 109a).

[00268] In some embodiments, the incoming ammonia stream 104 may first pass the hollow sidewalls 145, then subsequently pass the heat-exchanging conduits 144 in the bluff body 143, and then subsequently pass the preheating conduit 137. Preheating the stream 104 using the combination of the hollow sidewalls 145, the bluff body 143, and the preheating conduit 137 may advantageously increase ammonia conversion efficiency (e.g., by a synergistic or cumulative effect).

[00269] In some cases, instead of passing the bluff body 143 and the preheating conduit 137, the incoming ammonia stream 104 may first pass the hollow sidewalls 145, then subsequently pass a channel 146 (e.g., a fluid line) configured to direct the incoming ammonia stream 104 into the combustion-heated reformer 108 to be reformed by the NH3 reforming catalyst 130 therein.

Sidewalls for Injecting Air

[00270] As shown in FIG. 15, at least a portion of the combustion heater 109 may comprise hollow sidewalls 147 including a cavity configured to receive air (e.g., air stream 118 provided by the air supply unit 116 in fluid communication with the cavity of the hollow sidewalls 147).

[00271] The hollow sidewalls 147 may comprise a plurality of injection holes 148 (or apertures, slots, slits, etc.) adjacent to and/or facing toward inside the combustion heater 109. The plurality of injection holes 148 may be configured to inject air 118 into inside the combustion heater 119 in a staged injection pattern.

[00272] In some cases, the injection holes 148 enable a secondary injection path for the air stream 118 into the combustion heater 109 (in addition to a primary injection path for the air stream 118 via the burner head 134). The hollow sidewalls 147 may receive the air stream 118 via an inlet in the burner head 134, or may receive the air stream 118 via a separate inlet in the combustion heater 109. The secondary injection path for the air stream 118 may actively cool the walls of the combustion heater 109, thereby reducing thermal stress and durability issues. The secondary injection path for the air stream 118 may also enable staged combustion (e.g., fuel-rich combustion in the flame tube 109a near the burner head 134, and fuel -lean combustion further downstream in the flame tube 109a).

Fluidization Funnel

[00273] FIG. 16 is a schematic diagram illustrating a fluidization funnel 149 configured to inject fluidized particles 150 into the flame tube 109a, in accordance with one or more embodiments of the present disclosure.

[00274] The fluidized particles 150 may be configured to transfer heat from the combustion product gas 114 in the flame tube 109a to the NH3 reforming catalyst 130 in the combustion-heated reformer 108. The fluidization funnel 149 may be positioned adjacent to inlet(s) of the flame tube 109a (e.g., at or in the burner head 134). The fluidization funnel 149 may include the fluidized particles 150 therein, and may receive one or more fluid streams (e.g., the reformate stream 120 and/or the air stream 118) via the inlet(s).

[00275] The fluidization funnel 149 may be in fluid communication with the inlet(s), so that when the one or more fluid streams pass the fluidization funnel 149, the one or more fluid streams push the fluidized particles 150 into the combustion heater 109. The fluidized particles 150 may then absorb heat from the combustion product gas 114 and transfer the heat to the NH3 reforming catalyst 130 in the combustion-heated reformer 108 (e.g., by contacting the fluidized particles 150 with walls of the combustion heater 109).

[00276] The fluidized particles 150 may comprise sand, ceramic particles, metallic particles, beads, and/or pellets. Each of the fluidized particles 150 may comprise a size of at least about 100 microns to at most about 2 millimeters. The size may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 mm. The size may be at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 mm. In some cases, the size may be from about 0.1 mm to 2 mm, 0.2 mm to 1.8 mm, 0.3 mm to 1.6 mm, 0.4 mm to 1.4 mm, 0.5 mm to 1.2 mm, 0.6 mm to 1 mm, 0.7 mm to 0.9 mm, or 0.8 mm to 2 mm.

[00277] In some instances, a grated or perforated plate 151 may be positioned at or in an outlet of the combustion heater 109. The grated or perforated plate 151 may be configured to prevent escape of the fluidized particles 150 from the combustion heater 109 via the combustion exhaust 114.

Supply Tube for U-Turn Combustion

[00278] FIGS. 17A-17D are schematic diagrams illustrating a supply tube 152 for U-turn combustion in the combustion heater 109, in accordance with one or more embodiments of the present disclosure. The supply tube 152 may be positioned at least partially in the flame tube 109a and/or the burner head 134.

[00279] As shown in FIG. 17A, the supply tube 152 may comprise inlet(s) configured to receive at least part of the reformate stream 120 and/or the air stream 118. The inlet(s) may be at or adjacent to a first side of the combustion heater 109 (e.g., at, in or near the burner head 134).

[00280] The supply tube 152 may comprise outlet(s) (e.g., injection ports) configured to direct or inject the air stream 118 and/or at least part of the reformate stream 120 into the flame tube 109a. The outlet(s) may be at or adjacent to a second side of the combustion heater 109 opposite to the first side of the combustion heater 109.

[00281] The supply tube 152 and the flame tube 109a may be configured for U-turn combustion so that the air stream 118 and the reformate stream 120 pass through the supply tube 152 along a first direction from the first side of the combustion heater 109 to the second side of the combustion heater 109, and the hot combustion product gas 114 passes through the flame tube 109a along a second direction from the second side of the combustion heater 109 to the first side of the combustion heater 109 (i.e., the second direction is opposite the first direction). The U-turn combustion configuration may facilitate heat transfer from the combustion product gas 114 in the flame tube 109a to the NH3 reforming catalyst 130 in the combustion-heated reformer 108.

[00282] As shown in FIG. 17B, the supply tube 152 may comprise a reformate tube 152a configured to fluidically couple inlet(s) and outlet(s) of the supply tube 152, and direct the at least part of the reformate steam 120 into the combustion heater 109. The supply tube 152 may comprise an air tube 152b configured to fluidically couple inlet(s) and outlet(s) and direct the air stream 118 into the combustion heater 109. It is noted that the supply tube 152 may comprise any number of reformate tubes 152a and any number of air tubes 152b. In some embodiments, the supply tube 152 itself may be configured to receive both the reformate stream 120 and the air stream 118 (e.g., instead of separate tubes 152a and 152b).

[00283] In some cases, a length of the supply tube 152 (L 152) inside the flame tube 109a comprises of from about 0.1 to about 0.99 times the length of the flame tube 109a (L_109a). The length of the supply tube 152 (L 152) inside the flame tube 109a may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.99 times the length of the flame tube 109a (L_109a). The length of the supply tube 152 (L 152) inside the flame tube 109a may be at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.99 times the length of the flame tube 109a (L_109a). In some cases, the length of the supply tube 152 (L 152) inside the flame tube 109a may be from about 0.1 times to 0.99 times, 0.2 times to 0.9 times, 0.3 times to 0.8 times, 0.4 times to 0.8 times, 0.5 times to 0.7 times, or 0.6 times to 0.99 times the length of the flame tube 109a (L_109a). The length of the supply tube 152 (L 152) inside the flame tube 109a may be at most about 0.6 to about 0.9 times the length of the flame tube 109a (L_109a).

[00284] The diameter and/or length of the reformate tube 152a and/or the air tube 152b may be configured to control the injection location (and thereby the combustion location) and velocity of the reformate stream 120 and/or the air stream 118 in the combustion heater 109. The diameter and/or length of the reformate tube 152a may be the same or different as the diameter and/or length of the air tube 152b.

[00285] In some embodiments, a length of the reformate tube 152a (L_152a) and/or the air tube 152b (L_152b) inside the supply tube 152 may be of from about 0.1 to about 1 times the length of the supply tube 152 (L 152). The length of the reformate tube 152a (L_152a) and/or the air supply tube 152b (L_152b) inside the supply tube 152 may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 times the length of the supply tube 152 (L_152). The length of the reformate tube 152a (L_152a) and/or the air tube 152b (L_152b) inside the supply tube 152 may be at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 times the length of the supply tube 152 (L 152). In some cases, the length of the reformate tube 152a (L_152a) and/or the air tube 152b (L_152b) inside the supply tube 152 may be from about 0.1 times to 1 times, 0.2 times to 0.9 times, 0.3 times to 0.8 times, 0.4 times to 0.7 times, 0.5 times to 0.6 times the length of the supply tube 152 (L 152). The length of the reformate tube 152a (L_152a) and/or the air tube 152b (L_152b) inside the supply tube 152 may be at most about 0.5 to about 0.8 times the length of the supply tube 152 (L_152). [00286] In some instances, a diameter of the reformate tube 152a and/or the air tube 152b may be of from about 0.1 to about 0.95 times the diameter of the supply tube 152. The diameter of the reformate tube 152a and/or the air tube 152b may be at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times the diameter of the supply tube 152. The diameter of the reformate tube 152a and/or the air tube 152b may be at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times the diameter of the supply tube 152. In some cases, the diameter of the reformate tube 152a and/or the air tube 152b may be from about 0.1 times to 0.95 times, 0.2 times to 0.9 times, 0.3 times to 0.8 times, 0.4 times to 0.7 times, or 0.5 times to 0.6 times the diameter of the supply tube 152.

[00287] As shown in FIG. 17C, the reformate tube 152a may be positioned inside the air tube 152b (and the diameter of the reformate tube 152a may be smaller than the diameter of the air tube 152b).

[00288] In some cases, the air tube 152b may be positioned inside the reformate tube 152a (and the diameter of the air tube 152b may be smaller than the diameter of the reformate tube 152a).

[00289] As shown in FIG. 17D, the supply tube 152 may supply the air stream 118 and the reformate tube 152a may supply the reformate stream 120. In some instances, the supply tube 152 may supply the reformate 120 and the air supply tube 152b may supply the air 118.

[00290] In some embodiments, the supply tube 152, the reformate tube 152a, and/or the air tube 152b may extend into the flame tube 109a at a length that is at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 times the length of the flame tube 109a. The supply tube 152, the reformate tube 152a, and/or the air tube 152b may extend into the flame tube 109a at a length that is at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9 times the length of the flame tube 109a. In some cases, the supply tube 152, the reformate tube 152a, and/or the air tube 152b may extend into the flame tube 109a at a length that is from about 0.1 times to 0.9 times, 0.2 times to 0.8 times, 0.3 times to 0.7 times, 0.4 times to 0.6 times, or 0.5 times to 0.9 times the length of the flame tube 109a. The supply tube 152, the reformate tube 152a, and/or the air tube 152b may extend into the flame tube 109a at a length that is about 0.7 to about 0.9 times the length of the flame tube 109a.

Separate Burner Head Inlet Ports

[00291] FIG. 18 is a schematic diagram illustrating a burner head 134 including separate inlet ports 154 and 155, in accordance with one or more embodiments of the present disclosure. [00292] The burner head 134 may comprise a first inlet port 154 configured to receive a first fuel stream (e.g., the reformate stream 120), and a second inlet port 155 configured to receive a second fuel stream (e.g., the anode off-gas 128).

[00293] The first inlet port 154 and the second inlet port 155 are configured to be separate, and may thereby separate the first fuel stream and the second fuel stream. This separation of fuel streams may advantageously prevent backflow of one fuel stream to the other fuel stream. For instance, the reformate stream 120 may include trace or residual NH3, and the separation of the ports 154 and 155 may prevent the backflow of the trace or residual NH3 to the source of the anode off-gas 128 (the fuel cell 124). This backflow prevention may advantageously protect the fuel cell 124 from being damaged by trace or residual NH3.

Ammonia Filter Regenerators

[00294] FIGS. 19-21 are schematic diagrams illustrating various configurations for regenerating the ammonia filter 122 utilizing the heat of the combustion exhaust 114 (from the combustion heater 109), in accordance with one or more embodiments of the present disclosure. After being regenerated (i.e., after the saturated filter 122 is desorbed of ammonia), the ammonia filter 122 may be reused for ammonia filtration.

Regeneration of Ammonia Filter by Direct Contact

[00295] As shown in FIG. 19, the combustion exhaust 114 may be configured to exchange heat with the ammonia filter 122 by directly contacting the hot product gas 114 with the ammonia filter 122. The combustion heater 109 may fluidically communicate with the ammonia filter 122 via conduits 156.

[00296] In some embodiments, to initiate regeneration or desorption of the ammonia filter 122, an exhaust cover 158 may be actuated to a closed position at an exhaust outlet 157, and flow distribution valves 159 may be actuated to enable the combustion exhaust 114 to pass into the ammonia filter 122. The flow distribution valves 159 may also be actuated to prevent the reformate stream 120 from passing the ammonia filter 122 while regenerating the ammonia filter 122.

[00297] In some cases, an ammonia concentration sensor may be configured to detect an ammonia concentration at or in an outlet of the ammonia filter 122, or in the ammonia filter 122. When the ammonia concentration is equal to or greater than a threshold ammonia concentration (e.g., indicating saturation of the ammonia filter 122), the regeneration process may be initiated. In some instances, the threshold ammonia concentration may be at least about 0.01, 0.1, 1, 10, 100, or 1000 ppm. The threshold ammonia concentration may be at most about 0.01, 0.1, 1, 10, 100, or 1000 ppm. In some cases, the threshold ammonia concentration may be from about 0.01 ppm to 1000 ppm, 0.1 ppm to 100 ppm, or 1 ppm to 10 ppm.

[00298] In some cases, because ammonia adsorption is an exothermic process and may increase the temperature of the adsorbent, temperature measurements at, in, or adjacent to the ammonia filter 122 may be used to determine a degree of adsorbent saturation with ammonia.

[00299] In some cases, during the initial stage of the ammonia filtration process (i.e., where the adsorbent comprises a relatively high ammonia adsorption capacity), the temperature of the adsorbent at, in or adjacent to a first portion of the adsorbent (e.g., at, in or adjacent to an inlet for the reformate stream 120 in the ammonia filter 122) may be relatively higher than the temperature of the adsorbent at, in or adjacent to the other portions of the adsorbent (e.g., at, in or adjacent to an outlet for the reformate stream 120).

[00300] As the filtration and/or adsorption progress toward saturation, the temperature profile in the adsorbent may change. For example, the temperature at, in or adjacent to the inlet of the ammonia filter 122 may be relatively higher at an initial stage of the filtration, and subsequently the temperature at, in or adjacent to the outlet of the ammonia filter 122 may be relatively higher temperature at a later stage of the filtration.

[00301] In some cases, as the adsorbent is progressively saturated with ammonia, a temperature at, in or adjacent to an outlet of the adsorbent may increase, which may increase the temperature of the filtered reformate stream 123 output from the adsorbent. When the measured temperature of the adsorbent is equal to or greater than a threshold adsorbent temperature (e.g., indicating saturation of the ammonia filter 122), the regeneration process may be initiated.

[00302] In some cases, the temperature of the adsorbent may be measured at, in, or adjacent to an inlet of the ammonia filter 122 for the reformate stream 120, an outlet of the ammonia filter 122 for the filtered reformate stream 123, a central region of the ammonia filter 122 between the inlet and outlet, or the filtered reformate stream 123 output from the adsorbent. In some cases, the threshold adsorbent temperature may be at least about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than the ambient temperature. In some cases, the threshold adsorbent temperature may be at most about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than the ambient temperature.

[00303] To reinitiate the filtration of the reformate stream 120 by the ammonia filter 120, the exhaust cover 158 may be actuated to an opened position at the exhaust outlet 157, and the flow distribution valves 159 may be actuated to prevent the combustion exhaust 114 from passing into the ammonia filter 122. The flow distribution valves 159 may be actuated to let the reformate stream 120 pass into the ammonia filter 122 to remove residual or trace NH3 and output a filtered reformate stream 123.

[00304] It is noted that, in some embodiments, the flow distribution valves 159 may comprise a three-way valve 159. For example, the three-way valve 159 may comprise a first inlet fluidically coupled to the combustion heater 109 (to receive the combustion exhaust 114), a second inlet fluidically coupled to the reformer 108 and/or the reformer 110 (to receive the reformate stream 120), and an outlet fluidically coupled to the ammonia filter 122. To initiate the regeneration of the ammonia filter 122, the three-way valve 159 may be actuated to pass the exhaust 114 to the ammonia filter 122, and prevent the reformate stream 120 from passing the ammonia filter 122. To initiate filtration using the ammonia filter 122, the three-way valve 159 may be actuated to pass the reformate stream 120 to the ammonia filter 122, and prevent the combustion exhaust 114 from passing the ammonia filter 122.

Regeneration of Ammonia Filter by Heat Exchange

[00305] As shown in FIG. 20, the combustion exhaust 114 may be configured to exchange heat with the ammonia filter 122 by passing the combustion product gas 114 through one or more heat exchanging channels 160. The heat from the combustion product gas 144 may be transferred to the ammonia filter 122 via the walls of the heat exchanging channels 160. The combustion heater 109 may fluidically communicate with the heat exchanging channels 160, and the exhaust cover 158 may be actuated to a closed position to initiate the regeneration of the ammonia filter 122.

[00306] As shown in FIG. 21, the combustion exhaust 114 may be configured to exchange heat with the ammonia filter 122 by transferring heat from the combustion product gas 114 to an intermediate fluid 162 (e.g., water and/or a glycol). The intermediate fluid 162 may then circulate via the heat exchanging channels 160 to transfer heat to the ammonia filter 122.

[00307] As shown in both FIG. 20 and FIG. 21, in some embodiments, when operating with a fuel-rich combustion condition, air 161 may be injected into the combustion exhaust 114 (for example, near an entrance of the ammonia filter(s) 122 and/or into the heat exchanging channels 160) to bum excess hydrogen (for example, by low temperature catalytic combustion) and further heat the ammonia filter 122.

[00308] Exchanging heat via the heat exchanging channels 160 (as shown in FIGS. 20-21) may be advantageous compared to directly passing the combustion exhaust 114 through the ammonia filter 122, since water in the combustion exhaust 144 may accumulate and/or reduce ammonia filtration capacity in the ammonia filter 122. Cooling of Ammonia Filter

[00309] FIGS. 22-23 are schematic diagrams illustrating various configurations for cooling the ammonia filter 122, in accordance with one or more embodiments of the present disclosure.

[00310] As shown in FIG. 22, one or more coolant streams 163 (which may comprise the air stream 118 and/or the incoming ammonia stream 104) may pass a heat exchanging container 164 (e.g., a jacket) to remove heat from the ammonia filter 122. In some cases, the one or more coolant streams 163 may pass internal heat exchanging channels that contact the ammonia filter 122 to remove heat from the ammonia filter 122. Heat may be transferred from the ammonia filter 122 to the coolant stream(s) 163, thereby cooling the ammonia filter 122 and heating the air stream 118 and/or the ammonia stream 104 (before the streams 118 and/or 104 enter the reformer 108).

[00311] As shown in FIG. 23, a one-way cooling configuration 165 may be implemented, which entails passing a coolant stream 166 (e.g., ambient air sourced from the atmosphere) through the ammonia filter 122 (e.g., via the heat exchanging channels 160) and then discharging the coolant stream 166.

[00312] In some cases, as shown in FIG. 23, a looped cooling configuration 167 may be implemented, which entails passing a coolant stream 168 (e.g., water and/or a glycol) through the ammonia filter 122 (e.g., via the heat exchanging channels 160) to remove heat from the ammonia filter 122, and then subsequently transferring the heat to a heat exchanger 169. After passing the heat exchanger 169, the coolant stream 168 may be reused for removing heat from the ammonia filter 122.

[00313] It is noted that the cooling configurations described with respect to FIGS. 22-23 may be separate from the regeneration configurations described with respect to FIGS. 19-21.

Water Extraction Device

[00314] FIG. 24 is a schematic diagram illustrating a water extraction device 170 configured to extract water from the combustion exhaust 114 of the combustion heater 109, in accordance with one or more embodiments of the present disclosure. The water extracted by the extraction device 170 may be stored in a water collection tank 171. The water stored in the tank 171 may be provided to a faucet system (e.g., water tap) for drinking, cooking, bathing, etc.

[00315] In some embodiments, an electrolyzer (not shown) may be configured to electrolyze the water stored in the tank 171 to generate additional hydrogen (H2). The hydrogen may be stored in a hydrogen tank for later use, may be provided to the combustion heater 109 as combustion fuel, and/or may be provided to the fuel cell 124 to generate electricity.

[00316] In some cases, an inlet of the fuel cell 124 fluidically communicates with the water collection tank 171 so that the stored water in the water collection tank 171 humidifies the fuel cell 124. In some instances, an outlet of the fuel cell 124 fluidically communicates with the water collection tank 171 so that the water emitted by the fuel cell 124 is stored in the tank 171.

Thermoelectric Generator

[00317] FIG. 25 is a schematic diagram illustrating a thermoelectric generator 172 that utilizes heat from the combustion exhaust 114 of the combustion heater 109 to generate electricity 173, in accordance with one or more embodiments of the present disclosure.

[00318] In some embodiments, the thermoelectric generator 172 may provide the electricity 173 to power a compressor (not shown) in fluid communication with an inlet port of the combustion heater 109. The compressor may be configured to compress the air stream 118 (before the air stream 118 is provided to the combustion heater 109). This compression of the air stream 118 may facilitate combustion in the combustion heater 109.

[00319] In some instances, in addition to an external load being powered by the fuel cell 124 and/or a battery, the thermoelectric generator 172 may provide the electricity 173 to power the external load in addition to the fuel cell 124 (and/or a battery).

Turbocharger

[00320] FIG. 26 is a schematic diagram illustrating a turbocharger 174 (e.g., turbine) that utilizes the combustion exhaust 114 of the combustion heater 109, in accordance with one or more embodiments of the present disclosure.

[00321] The turbocharger 174 may be in fluid communication with the combustion heater 109 and may be configured to be driven (i.e., actuated using the heat and pressure of the combustion product gas 114) to compress the incoming air stream 118 (e.g., alternatively or additionally to the compression of the air stream 118 performed by the air supply unit 116). This compression of the air stream 118 may facilitate combustion in the combustion heater 109.

Conduit to Inject Secondary Stream

[00322] FIGS. 27-28 are schematic diagrams illustrating the burner head 134 with a preheating conduit 175 in the combustion heater 109, in accordance with one or more embodiments of the present disclosure. [00323] As shown in FIG. 27, the combustion heater 109 may be configured to receive a primary air stream 118a and a reformate stream 120 via the burner head 134, and a secondary air stream 118b via the preheating conduit 175. The primary air stream 118a and the secondary air stream 118b may be sourced from the air stream 118, or may be sourced separately from the air stream 118.

[00324] The secondary air stream 118b may advantageously provide mass flow at an outlet of the conduit 175 to reduce recirculation and flame holding near the burner head 134. The cooling provided by the secondary air stream 118b may reduce temperatures at or near the burner head 134(thereby alleviating thermal stress and durability issues in the flame tube 109a).

[00325] As shown in FIG. 28, the combustion heater 109 may be configured to receive a primary stream 177 via the burner head 134, and a secondary stream 178 via the preheating conduit 175. The primary stream 177 may be air or fuel (or both) (e.g., the reformate stream 120 and/or the air stream 118), and the secondary stream 178 may be air or fuel (or both). The conduit 175 may include an outlet to inject the secondary stream 178 into the combustion heater 109.

[00326] The preheating conduit 175 may be perforated with a plurality of injection holes 175a-f (or apertures, slots, slits, etc.) to inject the secondary stream 178 into the combustion heater 109 (downstream of the burner head 134). The injection holes 175a-f may be positioned along the longitudinal axis of the conduit 175 (which may be concentrically aligned with the longitudinal axis 131 of the combustion heater 109). The injection holes 175a-f may be variably sized to control the flow rate of fluid at each injection location (for example, the hole 175f closer to the burner head 134 may be smaller in size than the hole 175a closer to the outlet of the conduit 175). Although six injection holes 175a-f are shown, the injection holes 175a-f may comprise any number of holes 175a-f.

[00327] The injection holes 175a-f may advantageously inject fuel and/or air in an even distribution along the length of the preheating conduit 175, which may alleviate problems related to hotspots and overheating near the interface of the flame tube 109a and the burner head 134. The holes 175a-f may be positioned so that air (or fuel, or both) is injected tangentially into the combustion heater 109 (to induce swirl in the combustion product gas 114 and thereby improve heat transfer to the NH3 reforming catalyst).

[00328] In some cases, air/fuel combustion stoichiometry may be controlled to achieve multi-stage combustion in the combustion heater 109. For example, the primary stream 177 provided via the burner head 134 may comprise the reformate stream 120 to target a fuel-rich stoichiometry in a first region of the combustion heater 109, and the secondary stream 178 provided to the conduit 175 may comprise the air stream 118 to target a fuel-lean stoichiometry in a second region of the combustion heater 109.

Heat Exchanging Element in Reformer

[00329] FIGS. 29-32 are schematic diagrams illustrating heat exchanging elements 179 in the combustion-heated reformer 108, in accordance with one or more embodiments of the present disclosure.

[00330] The heat exchanging elements 179 may facilitate transfer of heat from the combustion heater 109 to the NH3 reforming catalyst 130 in the inner shell 132 and/or the outer shell 132 of the combustion-heated reformer 108. The heat exchanging elements 179 may comprise ceramic or metal, and may comprise fins, beads, honeycomb structures, meshes, screens, coils, wires and/or springs. In some embodiments, the heat exchanging elements 179 comprise a phase-change material (PCM) such as monobenzyl-toluene (MBT). In some instances, the heat exchanging elements 179 may be coated with NH3 reforming catalyst 130 (to further facilitate ammonia reforming).

[00331] As shown in FIG. 29, the heat exchanging elements 179 may be positioned in the outer shell 133. The reformate stream 120 from the inner shell 132 enters the outer shell 133, and the heat exchanging elements 179 in the outer shell 133 capture heat from the stream 120 and transfer the heat to the counter-flowing feed gas (e.g., the incoming ammonia stream 104 and/or the partially cracked reformate stream 120) in the inner shell 132.

[00332] As shown in FIG. 30, the heat exchanging elements 179 may be positioned in the inner shell 132, to transfer heat from the combustion heater 109 to the feed gas in the inner shell 132, and to the NH3 reforming catalyst 130 in the outer shell 133.

[00333] It is noted that the heat exchanging elements 179 may also be positioned in the inner shell 142 and/or the outer shell 143 of the electrically-heated reformer 110 (to facilitate transfer of heat from the electrical heater 111 to the NH3 reforming catalyst 130 in the electrically-heated reformer 110).

Heat Exchanging Element in Flame Tube

[00334] As shown in FIG. 31, the heat exchanging elements 179 may be positioned in the flame tube 109a, in accordance with one or more embodiments of the present disclosure. The heat exchanging elements 179 may be slidably insertable and/or removable in the flame tube 109a (and therefore may be easy to replace in the flame tube 109a).

[00335] In some embodiments, the heat exchanging elements 179 may comprise beads configured to induce turbulence in the combustion product gas 114 (thereby improving heat transfer to the NH3 reforming catalyst 130 in the reformer 108). A particle size of each of the beads 179 may comprise of from about 0.1 millimeter (mm) to 5 mm, of from 0.1 mm to 1 mm, of from 0.5 mm to 4.5 mm, of from 1 mm to 3 mm, or of from 1.5 mm to 2.5 mm. In some cases, the particle size of each of the beads 179 may be at least about 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mm. In some cases, the particle size of each of the beads 179 may be at most about 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mm.

[00336] As shown in FIG. 32, the heat exchanging elements 179 may comprise fins that extend from the walls of the flame tube 109a (and/or extend from the walls of the inner shell 132 or the outer shell 133). For example, the fins 179 may comprise a helical or curved shape that wraps around the inner walls of the flame tube 109a to swirl the combustion product gas 114 (thereby improving heat transfer to the NH3 reforming catalyst 130 in the reformer 108). In some cases, the fins 179 comprise a straight shape (e.g., substantially rectangular-cuboid).

[00337] In some instances, the fins 179 may comprise holes or apertures to tune heat transfer rates at different locations along the flame tube 109a. The holes of apertures may be smaller in size closer to a first side of the flame tube 109a opposite to the burner head 134 (an outlet side of the flame tube 109a), and larger in size closer to a second side of the flame tube 109a adjacent or near the burner head 134 (an inlet side of the flame tube 109a).

Radiant Tube

[00338] FIG. 33 is a schematic diagram illustrating radiant walls 201 of the combustion heater 109, in accordance with one or more embodiments of the present disclosure.

[00339] The flame tube 109a may comprise the radiant walls 201 configured to radiate heat (e.g., via incandescence) and thereby transfer heat to the NH3 reforming catalyst 130 in the reformer 108. The radiant walls 201 may be heated by the hot combustion product gas 114 in the flame tube 109a to a high temperature (such that the radiant walls 201 glow with a red or yellow color). The radiant walls 201 may be heated, for example, to a temperature of at least about 550 °C. The flame tube 109a including the radiant walls 201 may comprise a ceramic insert configured to incandesce and radiate heat. However, the present disclosure is not limited thereto, and the radiant walls 201 may comprise any material configured to radiate heat (for example, a metallic material). In some embodiments, the walls of the reformer 108, the walls of the reformer 110, and/or the walls of the electrical heater 111 may comprise the radiant walls 210. Flame Tube with High Thermal Conductivity Material Cladding

[00340] FIG. 34A is schematic diagram illustrating a high thermal conductivity cladding 203 positioned between two shells 202 and 204 of a flame tube 109b, in accordance with one or more embodiments of the present disclosure. The cladding 203 may comprise a high thermal conductivity material such as copper, graphite, and the like. The flame tube 109b may be inserted into the combustion heater 109 and/or the reformer 108 (e.g., similarly to the flame tube 109a), and may be configured to transfer heat to the catalyst 130 in the reformer 108.

[00341] The high thermal conductivity material cladding 203 may advantageously facilitate the distribution of flame heat throughout the flame tube 109b (thereby heating the catalyst 130 in the reformer 108 more uniformly). It is noted that the thermal conductivity of steel at about 500 °C is about 21.5 watt (W)/ meter-kelvin (m-K), while the thermal conductivity of copper at about 500 °C is about 386 W/m-K (which is 18 times higher). However, the melting point of copper (1084 °C) is lower than the melting point of steel stainless steel (1375 °C), and therefore care must be taken to avoid melting the copper (for example, by selecting an appropriate thickness of the copper cladding 203).

[00342] FIG. 34B is a conceptual image illustrating the advantageous thermal distribution across the flame tube 109b conferred by the high thermal conductivity material cladding 203 shown in FIG. 34A, in comparison to the flame tube 109a without the copper cladding 203.

Furnace Ammonia Reforming System

[00343] FIGS. 35A-35G are schematic diagrams illustrating a furnace ammonia reforming system 300, in accordance with one or more embodiments of the present disclosure.

[00344] As shown in FIG. 35A, a furnace 301 may comprise a plurality of reformers 308 therein. The reformers 308 may be arranged vertically, horizontally, or at an angle in the furnace 301. A burner 302 may be in fluid communication with the furnace 301 and may be configured to combust a fuel to heat the furnace 301 (e.g., via convection). The furnace 301 may comprise a rectangular shape, a circular shape, a cylindrical shape, and/or a triangular shape. FIG. 35B shows a top-view of the furnace chamber 301 including the plurality of reformers 308.

[00345] Each reformer 308 may comprise an inner tube 332 and an outer tube 333 comprising an NH3 reforming catalyst therein. In some cases, instead of an inner tube 332 (inner chamber) and an outer tube 333 (outer chamber), the reformers 308 may comprise straight tubes, pigtail tubes, U-shaped tubes, etc. After the reformers 308 are heated by the burner 302, the NH3 reforming catalyst may be configured to decompose the incoming ammonia stream 304 to generate a reformate stream 320 comprising hydrogen (H2) and nitrogen (N2). [00346] A storage tank configured to store NH3 may be in fluid communication with the reformers 308. An inlet manifold may be configured to direct an incoming ammonia stream 304 from the storage tank to the reformers 308. The inner tube 332 may be in fluid communication with an inlet manifold, and the outer tube 333 may be in fluid communication with an outlet manifold. The outlet manifold may be configured to direct the reformate stream 320 out of the reformers.

[00347] In some embodiments, the inner tube 332 may be in fluid communication with an outlet manifold, and the outer tube 333 may be in fluid communication with an inlet manifold. The outlet manifold may be configured to direct the reformate stream 320 out of the reformers 308.

[00348] In some instances, a U-turn reforming configuration may entail the inner tube 332 and the outer tube 333 being configured so that the NH3 passes the inner tube 332 along a first direction from a first side of the reformer 308 to a second side of the reformer 308 opposite to the first side, and so that the NH3 subsequently passes the outer tube 333 along a second direction from the second side to the first side.

[00349] In some cases, a U-turn reforming configuration may entail the inner tube 332 and the outer tube 333 being configured so that the NH3 passes the outer tube 333 along a first direction from a first side of the reformer 308 to a second side of the reformer 308 opposite to the first side, and so that the NH3 subsequently passes the inner tube 332 along a second direction from the second side to the first side.

[00350] As shown in FIG. 35C, the furnace ammonia reforming system 300 may be scaled to comprise a plurality of furnaces 301a-301i (including the reformers 308 therein). The scaled system 300 may generate a larger output of the reformate stream 320 (which may be combusted in an engine or consumed in a fuel cell to generate a power output of from about 10 kilowatts to about 1 gigawatt, or consumed in a chemical process, although the present disclosure is not limited thereto).

[00351] As shown in FIG. 35D, burners 302 may be positioned along a lateral side of the furnace 301 (instead of a top side or a bottom side, as shown in FIGS. 35A-35C), which may distribute heat to the reformers 308 more evenly. In some embodiments, a convective heat exchanger 310 may be in fluid communication with the furnace 301 and may be configured to receive a combustion exhaust 314 from the furnace 301. The convective heat exchanger 310 may be configured to transfer heat from the combustion exhaust 314 to the incoming ammonia stream 304 (e.g., from an NH3 storage tank) to evaporate and/or preheat the incoming ammonia stream 304. [00352] As shown in FIG. 35E, U-shaped reformers 308b including NH3 reforming catalyst therein may be configured to decompose the incoming ammonia stream 304 to generate a reformate stream 320 comprising H2 and N2. Each of the U-shaped reformers 308b may comprise a bend (e.g., which may be near or adjacent to the burner 302). The U-shaped reformers 308b may advantageously increase ammonia conversion efficiency (compared to the reformers 308 shown in FIGS. 36A-36D) by facilitating the distribution of heat to the NH3 reforming catalyst in the U-shaped reformers 308b.

[00353] An inner diameter of the U-shaped reformer(s) 308b may comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, or 90 centimeters. An inner diameter of the U-shaped reformer(s) 308b may comprise at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, or 90 centimeters. An outer diameter of the U-shaped reformer(s) 308b may comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, or 90 centimeters. An outer diameter of the U-shaped reformer(s) 308b may comprise at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, or 90 centimeters. In some cases, an outer diameter of the U- shaped reformer(s) 308b may be about 1 to 10, 10 to 20, 20 to 30, 30 to 40, 40 to 50, 50 to 60, 60 to 70, 70 to 80, or 80 to 90 centimeters. The U-shaped reformer(s) 308b may comprise a length of at least about 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 centimeters. The U-shaped reformer(s) 308b may comprise a length of at most about 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 centimeters. The U-shaped reformer(s) 308b may comprise a length of about 50 to 100, 100 to 200, 200 to 300, 300 to 400, 400 to 500, 500 to 600, 600 to 700, 700 to 800, 800 to 900, or 900 to 1000 centimeters.

[00354] The U-shaped reformers 308b may be configured to receive the incoming ammonia stream 304 at a target gas hourly space velocity (GSHV) comprising at least about 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 10000, 20000, or 30000 mL NH₃ * gcat’¹ * hr' f The U-shaped reformers 308b may be configured to receive the incoming ammonia stream 304 at a target gas hourly space velocity (GSHV) comprising at most about 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 10000, 20000, or 30000 mL NH₃ * gcat’¹ * hr ¹. A pressure drop of the ammonia stream 304 and/or the partially or substantially cracked reformate stream 320 across the U-shaped reformer(s) 308b may comprise at least about 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 bar. A pressure drop of the ammonia stream 304 and/or the partially or substantially cracked reformate stream 320 across the U-shaped reformer(s) 308b may comprise at most about 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 bar.

[00355] As shown in FIG. 35F, a partition 340 may be configured to separate the furnace 301 into separate chambers 341a and 341b. The partition 340 may be positioned adjacent or near the U-shaped reformers 308b (e.g., so that the partition 340 intersects the U-shaped reformers 308b at the bend of the U-shaped reformers 308b), and may be aligned along a center line of the furnace 301 and/or the reformers 308b.

[00356] A combustion product gas 314 emitted by the combustion of the burner 302 may rise in the chamber 341a and contact the walls of the U-shaped reformers 308b (thereby transferring heat to the NH3 reforming catalyst in the reformers 308b). The combustion product gas 314 may then pass through one or more apertures in the partition 340 to enter the chamber 341b, and may exit the furnace 301 via one or more outlets. In some embodiments, burners 302 may be positioned in both chamber 341a and chamber 341b (to facilitate the even distribution of heat to the catalyst in the U-shaped reformers 308b).

[00357] The partition 340 may increase residence time of the combustion product gas 314 in the furnace 301 (thereby facilitating heat transfer to the NH3 reforming catalyst), and may enable the tuning or control of flame heat distribution (e.g., by adjusting the number and/or size of the aperture(s) of the partition 340, or the thickness of the partition 340).

[00358] As shown in FIG. 35G, the furnace ammonia reforming system 300 may comprise U-shaped reformers 308c, each comprising an inner tube 332c and an outer tube 333c. Each of the U-shaped reformers 308c may comprise a bend (e.g., which may be near or adjacent to the burner 302). The inner tube 332c and/or the outer tube 333c may include NH3 reforming catalyst therein configured to decompose the incoming ammonia stream 304 to generate a reformate stream 320 comprising H2 and N2. The inner tube 332c may be in fluid communication with the outer tube 333c via a U-turn section. The incoming ammonia stream 304 may enter via the inner tube 332c and the reformate stream 320 may exit via the outer tube 333c. In some embodiments, the incoming ammonia stream 304 may enter via the outer tube 333c and exit via the inner tube 332c. The inner tube 332c and the outer tube 333c may increase residence time of the ammonia stream 304 in the U-shaped reformers 308c (thereby facilitating reforming of the ammonia stream 304 to the reformate stream 320)

Heat Exchanger Reformer

[00359] FIGS. 36A-36B are schematic diagrams illustrating a heat exchanger reformer 400, in accordance with one or more embodiments of the present disclosure.

[00360] As shown in FIG. 36A, reaction channels 402 may be in fluid communication with an ammonia reformer (e.g., the ammonia reforming system 100) and may be configured to receive a reformate stream (e.g., reformate stream 120), and./or may be in fluid communication with an ammonia storage tank (e.g., storage tank 102) and may be configured to receive an ammonia stream (e.g., ammonia stream 104).

[00361] The reaction channels 402 may comprise extended or corrugated surfaces that are coated or filled with NH3 reforming catalyst configured to decompose the ammonia into a reformate stream comprising hydrogen and nitrogen. Heat exchanging channels 401 may comprise extended or corrugated surfaces configured to transfer heat from a fluid stream to the reaction channels 402.

[00362] For example, as shown in FIG. 36B, the reaction channels 402 may be in thermal communication with the heat exchanging channels 401. A combustion exhaust 414 (e.g., substantially similar to the combustion exhaust 114) may enter the heat exchanger reformer 400 from an inlet. The relatively hot combustion exhaust 414 (e.g., greater than about 100 °C) may pass the heat exchanging channels 401 and transfer heat to the NH3 reforming catalyst in the reaction channels 402, thereby facilitating the decomposition of NH3 in the reaction channels 402. Although the combustion exhaust 414 is used as a heat exchanging fluid stream, other heat exchanging fluid streams may be utilized, for example, a reformate stream comprising hydrogen and nitrogen.

[00363] In some embodiments, the reaction channels 402 may fluidically communicate in series with the reformer 108 and/or the reformer 110, so that NH3 passes through the reaction channels 402, the reformer 108, and/or the reformer 110 (in any order). This series configuration may advantageously increase the overall ammonia conversion efficiency (compared to using only the channels 402, the reformer 108, or the reformer 110 to decompose ammonia).

[00364] In some instances, the heat exchanger reformer 400 comprises a plate-type heat exchanger, shell-and-tube type heat exchanger, or a tube-in-tube type heat exchanger. In some cases, the reaction channels 402 and/or the heat exchanging channels 401 comprise metal meshes (or other heat exchanging element) configured to improve transfer of the heat. In some embodiments, a portion of the heat exchanger reformer 400 is configured to evaporate or preheat an incoming ammonia stream (e.g., incoming ammonia stream 104).

[00365] In some cases, a spacing between the extended or corrugated surfaces (of the channels 401 or the channels 402) comprises of from about 0.1 mm to about 50 mm. In some embodiments, the spacing between one or more extended or corrugated surfaces comprises at least about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some instances, the spacing between one or more extended or corrugated surfaces comprises at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. In some cases, the spacing between one or more extended or corrugated surfaces comprises from about 0.1 mm to 50 mm, 0.5 mm to 40 mm, 1 mm to 30 mm, 2 mm to 20 mm, 3 mm to 10 mm, 4 mm to 9 mm, 5 mm to 8 mm, or 6 mm to 7 mm.

[00366] In some embodiments, the NH3 reforming catalyst comprises ruthenium and/or nickel as an active metal, and/or an active metal comprising a diameter of from about 1 nm to about 1000 nm. In some cases, the active metal comprises a diameter of at least about 1 nm, 10 nm, 100 nm, or 1000 nm to at most about 1 nm, 10 nm, 100 nm, or 1000 nm. In some cases, the active metal comprises a diameter of from about 1 nm to 1000 nm or 10 nm to 100 nm.

[00367] Any of the ammonia reformer configurations and concepts described herein, can be used to generate and store hydrogen for one or more chemical processes, hydrogen refueling stations, power generation using one or more fuel cells, or as an auxiliary fuel, pilot fuel, or main fuel for combustion engines.

Multi-Channel Reformer

[00368] FIGS. 37A-37D are schematic diagrams illustrating a multi-channel reformer 500a, in accordance with one or more embodiments of the present disclosure. The multi-channel reformer 500a may comprise a plurality of reforming channels enclosed by a single housing comprising a circular cross-section. The inner shells 532a and/or the outer shell 533a may comprise NH3 reforming catalyst therein configured to reform ammonia into hydrogen and nitrogen. The multi-channel reformer 500a may comprise a plurality of inlets configured to receive ammonia stream(s) 504, and a plurality of outlets configured to output reformate stream(s) 520. As shown in FIGS. 37A-37D, the inlets may be parallel with the longitudinal axis of the multi-channel reformer 500a, and the outlets may be perpendicular to the longitudinal axis of the multi-channel reformer 500a.

[00369] In some cases, the multi-channel reformer 500a may comprise embedded heating element(s) 509 comprising an outer surface that is configured to be in thermal communication with a fluid (e.g., incoming ammonia stream(s) 504) passing through the reformer 500a via inner shells 532a (i.e., flow channels surrounding the embedded heating elements 509). In some cases, the heating element(s) 509 may be configured to provide a plurality of heating zones within the reformer 500a. In some cases, the plurality of heating zones may comprise different temperatures that are predetermined or adjustable. In some cases, the embedded heating elements 509 may comprise a combustion heater, an electrical heater, or a hybrid heating element comprising both a combustion heater and an electrical heater. In some cases, a hybrid heating element may enable a fast initiation of ammonia reforming, a compact volume, and facile control of temperature.

[00370] The multi-channel reformer 500a may comprise two catalysts provided in two different regions or heating zones (e.g., a low-temperature region 550a and a high-temperature region 550b). In some cases, a low-temperature catalyst (that is efficient at lower temperatures) may be provided in the region 550a, and a high-temperature catalyst (that is efficient at higher temperatures) may be provided in the region 550b. In some cases, the first region may be closer to the inlets and/or outlets of the multi-channel reformer 500a than the second region [00371] FIGS. 38A-38D are schematic diagrams illustrating a multi-channel reformer 500b, in accordance with one or more embodiments of the present disclosure. The multi-channel reformer 500b may comprise a plurality of reforming channels enclosed by a single housing comprising a rectangular cross-section. The inner shells 532b and/or the outer shell 533b may comprise NH3 reforming catalyst therein configured to reform ammonia into hydrogen and nitrogen. The multi-channel reformer 500b may comprise a plurality of inlets configured to receive ammonia stream(s) 504, and a plurality of outlets configured to output reformate stream(s) 520. As shown in FIGS. 38A-38D, the inlets and the outlets may be perpendicular to the longitudinal axis of the multi-channel reformer 500b.

[00372] FIG. 39A is a schematic diagram illustrating multi-channel reformers 500a-500d comprising various cross-sectional shapes or profiles, in accordance with one or more embodiments of the present disclosure. The multi-channel reformer 500c comprises half the length of the multi-channel reformer 500b. The inner shells and heating elements of the multichannel reformer 500d comprise half the volume of the channels and heating elements of the multi-channel reformer 500b.

[00373] A multi-channel reformer 500a-500d may comprise, but is not limited to, circular, triangular, rectangular, pentagonal, hexagonal, heptagonal, or octagonal cross-sectional shapes or profiles. In some cases, the multi-channel reformer 500a-500d may comprise a cross-sectional shape comprising a circle, an ellipse, an oval, or any polygon comprising three or more sides. In some cases, the multi-channel reformer 500a-500d may comprise a cross-sectional shape that is similar to a cross-sectional shape of the flow channels (inner shell). In some cases, the multichannel reformer 500a-500d may comprise a cross-sectional shape that is different than a cross- sectional shape of the flow channels.

[00374] In some cases, the cross-sectional shape of the reformers 500a-500d may permit stacking of a plurality of multi-channel reformers 500a-500d. In some cases, a plurality of multichannel reformers 500a-500d may be stacked horizontally (i.e., laying down) or vertically (i.e., standing up). In some cases, a plurality of reformers 500a-500d may be stacked in a rectangular or square grid pattern. In some cases, a plurality of reformers 500a-500d may be stacked in a hexagonal grid pattern (i.e., honeycomb). In some cases, a plurality of reformers 500a-500d may be stacked and connected linearly.

[00375] In some cases, the length of a multi-channel reformer 500a-500d may be at least about 5 times the width or diameter of the reformer 500a-500d. In some cases, the length of a multi-channel reformer 500a-500d may be at least about 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the width or diameter of the reformer 500a-500d. In some cases, the length of the multi-channel reformer 500a-500d may be at most about 2, 3, 4, 5, 6, 7, 8, 9, or 10 times the width or diameter of the multi-channel reformer 500a-500d. In some cases, the length of the multi-channel reformer 500a-500d may be from about 2 times to 10 times, 3 times to 9 times, 4 times to 8 times, 5 times to 7 times, 6 times to 10 times the width or diameter of the multi-channel reformer 500a-500d. In some cases, the length of the multi-channel reformer 500a-500d may be at most about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 times the width or diameter of the reformer 500a- 500d. In some cases, the length of the multi-channel reformer 500a-500d may be at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 times the width or diameter of the reformer 500a-500d. In some cases, the length of the multi-channel reformer 500a-500d may be from about 10 times to 100 times, 20 times to 90 times, 30 times to 80 times, 40 times to 70 times, 50 times to 60 times the width or diameter of the reformer 500a-500d.

[00376] The multi-channel reformers 500a-500d may comprise any number of inlets and/or outlets (e.g., two or four inlets and/or outlets). In some cases, four outlets are positioned symmetrically such that the reformate stream 520 is directed to each of the four sides of the multi-channel reformer 500a-500d. In some cases, multiple outlets may be positioned symmetrically. In some cases, multiple outlets may comprise substantially equal cross-sectional areas. In some cases, multiple outlets may be positioned at one end of a multi-channel reformer 500a-500d. In some cases, multiple outlets may be positioned on multiple sides of a multichannel reformer 500a-500d.

[00377] FIG. 39B is a plot illustrating thermal reforming efficiencies for the various multi-channel reformers 500a-500d as a function of ammonia flow rate. Measurements were performed using electrical Joule heating. The temperature of the incoming ammonia stream was about 25 °C. The ammonia stream was tested to about 300 standard liters per minute (LPM), where an about 99% conversion provides enough hydrogen for an electrical power of about 40 kW output from a fuel cell. Thus, scaling the reformer design to support about 100+ kW operations may be possible, for example, with a multi-channel reformer 500a-500d having a longer length, or larger channel dimensions and heating elements, more channels and heating elements, or by stacking modular multi-channel reformers. The multi-channel reformers 500a- 500d may be constructed with great flexibility in form factor, which may enable the use of multiple modular multi-channel reformers in a system. Utilizing heat exchangers between hot outlet flow (about 400-500 °C) and cold inlet flow (around 25 °C) may significantly increase the thermal reforming efficiency (e.g., about 92-95% or greater).

[00378] FIG. 39C is a plot illustrating ammonia conversion efficiency for the multichannel reformers 500a-500d as a function of ammonia flow rate. In some cases, the multichannel reformers 500a-500d may have an ammonia conversion efficiency of at least about 95% (i.e., at least about 95% of ammonia is converted to H2 and N2). In some cases, the multichannel reformers 500a-500d may have an ammonia conversion efficiency of at least about 50, 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%. In some cases, the reformer may have an ammonia conversion efficiency of at most about 50, 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%, or 100%. In some cases, the reformer may have an ammonia conversion efficiency of from about 50% to 100%, 60% to 99%, 70% to 98%, 80% to 97%, 90% to 96%, 91% to 95%, 92% to 94%, or 93% to 100%.

The multi-channel reformers 500a-500d may be sized appropriately to generate various levels of power. In some cases, a multi-channel reformer 500a-500d may be configured to output at least about 25 kilowatts of power. In some cases, a multi-channel reformer 500a-500d is configured to output at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500 kilowatts of power. In some cases, a multi-channel reformer 500a-500d may be configured to output at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500 kilowatts of power. In some cases, a multi-channel reformer 500a-500d may be configured to output from about 1 kilowatts to 500 kilowatts, 2 kilowatts to 400 kilowatts, 3 kilowatts to 300 kilowatts, 4 kilowatts to 200 kilowatts, 5 kilowatts to 100 kilowatts, 6 kilowatts to 90 kilowatts, 7 kilowatts to 80 kilowatts, 8 kilowatts to 70 kilowatts, 9 kilowatts to 60 kilowatts, 10 kilowatts to 50 kilowatts, 20 kilowatts to 40 kilowatts, 30 kilowatts to 500 kilowatts of power. In some cases, the multi-channel reformers 500a-500d may be configured to output at most about 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50 megawatts of power. In some cases, the multi-channel reformers 500a-500d may be configured to output from about 0.1 megawatts to 50 megawatts, 1 megawatts to 40 megawatts, 2 megawatts to 30 megawatts, 3 megawatts to 20 megawatts, 4 megawatts to 10 megawatts, 5 megawatts to 9 megawatts, 6 megawatts to 8 megawatts, or 7 megawatts to 50 megawatts of power. External Reformers

[00379] FIGS. 40A-40F are schematic diagrams illustrating various externally-heated reformer configurations 600a-f, in accordance with one or more embodiments of the present disclosure.

[00380] The externally heated reformers 108 in the reformer configurations 600a-f may be heated from the outside (for example, the combustion heater 109 may at least partially surround the reformer 108). The combustion exhaust 109 may physically contact a wall separating the combustion heater 109 and the reformer 108. The combustion exhaust 114 may convectively transfer heat from the combustion heater 109 to the reformer 108 in an inward direction (e.g., a radially inward direction toward a longitudinal axis at the center of the reformer configurations 600a-600f).

[00381] As shown in FIG. 40A, in some cases, the reformer 108 and the combustion heater 109 may be aligned about a central longitudinal axis 601 (e.g., concentrically). The reformer 108 may include an outer shell 108a and an inner shell 108b. An outer diameter or width of the inner shell 108b may be at a first radial distance from the longitudinal axis 601, an outer diameter or width of the outer shell 108a may be at a second radial distance from the longitudinal axis 601 (greater than the first radial distance), and an outer diameter or width of the combustion heater 109 may be at a third radial distance from the longitudinal axis 601 (greater than the first radial distance and the second radial distance). In this way, the outer shell 108a may at least partially surround the inner shell 108b, and the combustion heater 109 may at least partially surround the outer shell 108a

[00382] In some cases, the inner shell 108a may include a first NH3 reforming catalyst 101a, and the outer shell 108b may include a second NH3 reforming catalyst 101b. The first NH3 reforming catalyst 101a and the second NH3 reforming catalyst 101b may be the same type of catalyst (for example, a ruthenium based catalyst). The first NH3 reforming catalyst 101a and the second NH3 reforming catalyst 101b may be different types of catalyst (for example, the first NH3 reforming catalyst 101a may be ruthenium based, while the second NH3 reforming catalyst 101b may be nickel based).

[00383] Although FIG. 40A shows the ammonia stream 104 entering the outer shell 108a and the reformate stream 120 exiting the inner shell 108b, in some cases, it is contemplated that the ammonia stream 104 may instead enter the inner shell 108b and exit the outer shell 108a (for any of the configurations of the reformer 108 and the combustion heater 109 of the present disclosure). [00384] As shown in FIG. 40B, in some cases, the burner head 134 of the combustion heater 109 may comprise a primary air inlet 603 configured to receive a primary air stream 118a and a reformate inlet 602 configured to receive the at least part of the reformate stream 120 (e.g., at least part of a second reformate stream generated by the reformer 108, as opposed to a first reformate stream generated by the electrically-heated reformer 110). The primary air inlet 603 and the reformate inlet 602 may be separate inlets. The primary air inlet 603 and the reformate inlet 602 may be the same inlet (for example, forming a shared annulus space). The primary air stream 118a and the reformate stream 120 may be injected into the combustion heater 109 in a swirling pattern, which may advantageously swirl the combustion exhaust 114 and increase heat transfer to the reformer 108.

[00385] In some cases, a secondary air inlet 175 may be configured to receive a secondary air stream 118b, and inject the secondary air stream 118b into the combustion heater 109a (e.g., toward the reformer 108 and along the central longitudinal axis 601). This injection of the secondary air stream 118b may lower a flame temperature of the combustion in the heater 109, which may advantageously reduce thermal stress in the walls of the reformer 108 and the combustion heater 109 adjacent to the flame .

[00386] In some cases, the primary air inlet 603 and the reformate inlet 602 form an annulus (e.g., in the burner head 134), and the secondary air inlet 175 is positioned at a center of the annulus. In some cases, the secondary air inlet 175 comprises a cylindrical conduit. In some cases, the secondary inlet 175 is configured to mix the secondary air stream 118b and at least part of the reformate stream 120, or receive a mixture of the secondary air stream 118b and at least part of the reformate stream 120 (for example, a premixture).

[00387] As shown in FIG, 40C, in some cases, an air preheating section 604 at least partially surrounds the combustion heater 109, and may be configured to receive the air stream 118. The air preheating section 604 may be in thermal communication with the combustion heater 109, and the air preheating section 604 may preheat the air stream 118 before providing the air stream 118 to the combustion heater 109 for combustion. For example, the combustion exhaust 114 may transfer heat to the air stream 118 across the wall separating the combustion heater 109 from the air preheating section 604 (for example, by convective heat transfer).

[00388] The air preheating section 604 may form an annulus (e.g., void or cavity in the form of an annulus) that surrounds the combustion heater 109 (although the present disclosure is not limited thereto; for example, the air preheating section 604 may comprise one or more conduits or tubes in thermal communication with the combustion heater 109). In some cases, the air stream 118 in the air preheating section 604 and the combustion exhaust 114 in the combustion heater 109 are arranged in a counter flow configuration, such that the air stream 118 travels in a first direction, and the combustion exhaust 114 travels in a second direction opposite to the first direction. In this way, the air preheating section 604 may advantageously cool the walls of the combustion heater 109, while simultaneously preheating the air stream 118 (which may lower the fuel requirement for combustion).

[00389] As shown in FIG. 40D, in some cases, a plurality of injection holes 604a-f may be configured to inject the air stream 118 into the combustion heater 109 and toward the reformer 108 from the air preheating section 604. The injection holes 604a-f may be positioned along a wall separating the air preheating section 604 and the combustion heater 109. The injection holes 604a-f may be variably sized along a length of the combustion heater 109 (along the wall). For example, the injection holes 604a-f may be progressively smaller along the length of the combustion heater 109 (along the wall). In some cases, the injection holes 604a-f may be larger closer to an inlet of the the air preheating section 604 configured to receive the air stream 118, and smaller closer to an outlet of the air preheating section 604 configured to output the air stream 118 (for example, closer to the flame in the combustion heater 109). In this way, staged combustion may be achieved in the combustion heater 109 such that the combustion closer to the flame is fuel-rich (e.g., stoichiometric excess of fuel or hydrogen) and that the combustion further from the flame is fuel-lean (e.g., stoichiometric excess of air or oxygen), which advantageously reduces nitrogen oxide emissions. Although six injection holes 604a-f are shown, the injection holes 604a-f may comprise any number of injection holes.

[00390] As shown in FIG. 40E, in some cases, a heat exchanging element 641a-b may be configured to transfer heat from the combustion exhaust 114 in the combustion heater 109 to the reformer 108 (in other words, facilitate the transfer of heat). In some cases, the heat exchanging elements 641a-b may be similar or identical to the heat exchanging elements 179 described with respect to FIGS. 30-32.

[00391] The heat exchanging elements 641a and 641b may be affixed, attached, or secured to surfaces or walls of the reformer 108. For example, the heat exchanging element 641a may be attached, affixed, or secured to an outer surface of the reformer 108 (for example, on an outer surface of the wall separating the combustion heater 109 from the outer shell 108a of the reformer 108), and the heat exchanging element 641b may be attached, affixed, or secured to an inner surface of the reformer 108 (for example, on an inner surface of the wall separating the combustion heater 109 from the outer shell 108a of the reformer 108).

[00392] In some cases, the heat exchanging elements 641a -b may comprise fins, vanes, or baffles that extend from the reformer 108. In some cases, the heat exchanging elements 641a-b comprise helical (spiral) features, for example, a wire or a spiral vane that winds around the wall separating the combustion heater 109 from the outer shell 108a of the reformer 108.

[00393] In some cases, a pitch (period) of the helical feature (e.g., the distance between each complete spiral along the length of the reformer 108) may vary. For example, the pitch may be larger closer to the flame in the combustion heater 109 (closer to the inlets for the reformate stream 120 and the air stream 118), and the pitch may be smaller further from the flame in the combustion heater 109. In this way, the heat exchanging elements 641a-b may control the distribution of heat to the reformer 108 such that the region of the reformer 108 closer to the flame does not overheat (since the larger pitch of the helical feature facilitates less heat transfer compared to the smaller pitch). As shown in FIG. 40F, in some cases, a blockage structure 650 may be positioned in the inner shell 108b. The blockage structure 650 may be configured to decrease a volume of the inner shell 108b and divert the flow of the ammonia stream 104 (and/or the reformate stream 120) in the inner shell 108b. For example, the flow may be diverted into a narrower volume of the inner shell 108b, and therefore the transfer of heat to the catalyst 101b and the ammonia stream 104 may be facilitated (thereby facilitating the generation of the reformate stream 120). In some cases the blockage structure has a cylindrical or rectangular cuboid shape.

[00394] In some cases, the blockage structure 650 comprises a heat exchanging element 655 configured to transfer heat from the combustion exhaust 114 to the reformer 108. For example, the heat exchanging element 655 may be attached, affixed, or secured to the blockage structure 650 (for example, the heat exchanging element 655 may wind around the blockage structure 650). The heat exchanging element 655 may be similar or identical to the similarly- named heat exchanging elements described elsewhere in this disclosure, and may comprise fins, vanes, baffles, and/or a helical feature.

[00395] In some cases, an insulating material 654 may line at least a portion of the reformer 108 (for example, a thermal coating that lines an outside surface of the reformer 108 on the wall separating the reformer 108 from the combustion heater 109). The insulating material 654 may comprise a ceramic material, for example, alumina and/or silica based materials. In some cases, the insulating material 654 may cover less than about 50% of the surface area of the reformer 108 (for example, the outer surface area of the ref ormer 108 facing the combustion heater 109). In some cases, the insulating material covers less than about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% of the surface area of the reformer 108. The insulating material 654 may advantageously reduce the transfer of heat from the combustion exhaust 114 to a region of the reformer 108 closer to the flame in the combustion heater 109 (for example, closer to the burner head 134), thereby reducing thermal stress to the walls of the reformer 108.

[00396] In some cases, an oxidation resistant material (for example, an oxide) may line a portion of the reformer 108, which may reduce oxidation damage to the walls of the reformer 108. In some cases, the insulating material 654 may cover (overlay) the oxidation resistant material. In some cases, the oxidation resistant material covers more than 50% of the surface area of the reformer 108.

[00397] In some cases, a refractory material 653 may line an inner surface of the combustion heater 109 (for example, an inner surface of the wall of the combustion heater 109). The refractory material 653 may comprise ceramic fibers (such as alumina or silica based fibers) and may be manufactured by vacuum forming. In some cases, a rigidizer (e.g., silica based) may be used to reinforce the refractory material 653. The refractory material 653 may advantageously trap heat inside the combustion heater 109 which may facilitate the heating of the reformer 108 by reducing heat loss (and may also facilitate heat transfer via radiation in addition to the convective heat transfer of the combustion exhaust 114). In some cases, a metal lining (e.g., comprising steel) may cover the refractory material 653, which may increase the durability of the combustion heater 109.

Decoupled Reformers

[00398] FIGS. 41A-41E are schematic diagrams illustrating various reformer configurations 700a-700e where the reformer 108 is decoupled from the combustion heater 109, in accordance with one or more embodiments of the present disclosure. The reformer 108 and the combustion heater 109 may be decoupled such that a flame in the combustion heater 109 does not physically contact (e.g., impinge) the reformer 108. In this way, thermal stress to the walls of the reformer 108 may be reduced. It is noted that any of the configurations of the reformer 108 and combustion heater 109 described with respect to any of FIGS 1A-42D may be decoupled, such that the flame of the combustion heater 109 does not impinge on the reformer 108.

[00399] In some cases, the reformer 108 and the combustion heater 109 may be decoupled as separate structures, such that the reformer 108 and the combustion heater 109 are attachable and detachable (for example, slidably insertable and removable, and/or by using fasteners such as screws, nuts and bolts). In some cases, the reformer 108 and the combustion heater 109 share the same housing or vessel, but may be decoupled by a partition or wall separating the combustion heater 109 from the reformer 108. [00400] As shown in FIG. 41 A, in some cases, the reformer 108 may have an inverted U- shape. The combustion heater 109 may be decoupled from the inverted U-shaped reformer 108. The combustion may occur in the heater 109 and the exhaust 114 may be transferred to a combustion heating section 716 in thermal communication with the reformer 108 (for example, via an exhaust conduit 715).

[00401] The combustion exhaust 114 may be provided to a first section 716a of the combustion heating section 716 (where the combustion exhaust 114 first contacts a wall of the inner shell 108a to transfer heat to the inner shell 108a) and subsequently the combustion exhaust 114 may be provided to a second section 716b of the combustion heating section 716 (so that the combustion exhaust 114 contacts a wall of the outer shell 108b to transfer heat to the outer shell 108b). In some cases, the opposite may occur, such that the combustion exhaust 114 is first provided to the section 716b to transfer heat to the outer shell 108b, and the exhaust 114 may then subsequently be provided to the section 716a to transfer heat to the inner shell 108a. In some cases, the inner shell 108b may include a conductive media (for example, ceramic or metallic beads) and the outer shell 108a may include NH3 reforming catalyst (e.g., the catalysts 101a and/or 101b), or vice versa.

[00402] In some cases, an air preheating section 717 at least partially surrounds the combustion heating section 717 and is configured to receive the air stream 118. The air preheating section 717 may form an annulus (e.g., an annulus shaped void or cavity) or may comprise one or more tubes or conduits. The air preheating section 717 may be in thermal communication with the combustion heating section 716, and may be configured so that the combustion exhaust 114 in the combustion heating section 716 transfers heat to the air stream 118 in the air preheating section 717. In some cases, the air stream 118 in the air preheating section 717 and the combustion exhaust 114 in the combustion heating section 716 are arranged in a counter flow configuration (so that the combustion exhaust 114 travels in a first direction, and the air stream 118 travels in a second direction opposite to the first direction).

[00403] As shown in FIG. 41B, in some cases, a partition 720 may separate the reformer 108 and the combustion heating section 726 from the combustion heater 109. In some cases, the partition 720 may be part of the same housing shared by the reformer 108, the combustion heating section 726, and/or the combustion heater 109 (forming a unitary structure). In some cases, the partition 720 may divide a first structure (comprising the reformer 108 and the combustion heating section 726) from a second structure (comprising the combustion heater 109). In contrast to the configuration 700a shown in FIG. 41A, the combustion exhaust 114 may only contact the outer shell 108a (instead of both the outer shell 108a and the inner shell 108b). [00404] As shown in FIG. 41B, in some cases, a staged air stream 718a may be injected into the combustion heater 109 to achieve staged combustion in the combustion heater 109. For example, the air stream 118 may include a stoichiometric deficit of oxygen with respect to the hydrogen in the reformate stream 120, and the staged air stream 718a may include a stoichiometric excess of oxygen with respect to the hydrogen in the reformate stream 120. The staged combustion may advantageously reduce nitrogen oxide emissions. In some cases, a dilution air stream 718b may be injected to dilute and cool the exhaust 114, thereby reducing damage to the walls of the combustion heater 109, the combustion heating section 726, and/or the reformer 108.

[00405] As shown in FIG. 41C. in some cases, the combustion heating section 726 may include a partition 725 including a plurality of injection ports 725a-i configured to inject the combustion exhaust 114 toward the reformer 108 (e.g., such that the exhaust 114 impinges the wall separating the reformer 108 from the combustion heating section 726). The injection ports 725a-i may advantageously distribute the exhaust 114 evenly to the reformer 108 (throughout the combustion heating section 726). Although nine injection ports 725a-i are shown, the injection ports 725a-i may comprise any number of injection ports.

[00406] As shown in FIG. 41D, an exhaust conduit 727 may transfer the combustion exhaust 114 from the combustion heater 109 to the combustion heating section 726, so that the exhaust 114 contacts a wall separating the section 726 from the inner shell 108b, and then subsequently contacts a wall separating the section 726 from the outer shell 108a.

[00407] As shown in FIG. 41E, in some cases, an exhaust conduit 737 may transfer the part of the combustion exhaust 114 from the combustion heater 109 to the combustion heating section 726, so that the exhaust 114 contacts a wall separating the section 726 from the inner shell 108b. In some cases, the exhaust conduit 727 includes a plurality of injection holes 737a-j configured to inject the combustion exhaust 114 into the combustion heating section 726 and toward the reformer 108 (so that the combustion exhaust impinges normally on a surface of the wall separating the section 726 from the inner shell 108b). Although ten injection holes 737a-j are shown, the holes 727a-j may comprise any number of injection holes.

[00408] In some cases, the combustion heating section 726 may include a partition 735 including a plurality of injection ports 735a-h configured to inject the combustion exhaust 114 toward the reformer 108 (e.g., such that the exhaust 114 impinges normally on a surface of the wall separating the reformer 108 from the combustion heating section 726). The injection ports 735a-h may advantageously distribute the exhaust 114 evenly to the reformer 108 (throughout the combustion heating section 726). Although eight injection ports 735a-h are shown, the injection ports 735a-h may comprise any number of injection ports.

Ammonia Preheating Section

[00409] FIGS. 42A-42D are schematic diagrams illustrating various reformer configurations 800a-d that include an ammonia preheating section 820, in accordance with one or more embodiments of the present disclosure.

[00410] The internally-heated reformers 108 in the reformer configurations 800a-d may be heated from the inside (for example, the reformer 108 may at least partially surround the combustion heater 109). The combustion exhaust 109 may physically contact a wall separating the combustion heater 109 and the reformer 108. The combustion exhaust 114 may convectively transfer heat from the combustion heater 109 to the reformer 108 in an outward direction (e.g., a radially outward direction away from a longitudinal axis at the center of the reformer configurations 800a-800d).

[00411] As shown in FIG. 42A, the ammonia preheating section 820 may receive and heat the ammonia stream 104 before the ammonia stream 104 is provided to the reformer 108. The internally-heated reformers 108 in the reformer configurations 800a-d may be heated from the inside (for example, the reformer 108 may at least partially surround the combustion heater 109). The combustion exhaust 114 may physically contact a wall separating the combustion heater 109 and the reformer 108. The combustion exhaust 114 may convectively transfer heat from the combustion heater 109 to the reformer 108 in an outward direction (e.g., a radially outward direction away from a longitudinal axis at the center of the reformer configurations 800a-800d).

[00412] The NH3 (i.e. ammonia) preheating section 820 may be in thermal communication with the combustion heater 109, and may be configured to transfer heat from the combustion exhaust 114 in the combustion heater 109 to the ammonia stream 104 in the NH3 preheating section 820. For example combustion exhaust 114 may physically contact a wall separating the combustion heater 109 and the NH3 preheating section 820.

[00413] In some cases, the combustion heater 109 may at least partially surround the NH3 preheating section 820. In some cases, the NH3 preheating section 820 may at least partially surround the combustion heater 109.

[00414] In some cases, the NH3 preheating section 820 may include an inner section 820b and an outer section 820a. In some cases, the inner section 820b is a conduit or tube (e.g., having a cylindrical or rectangular-cuboid shape), and the outer section 820a is an annulus (e.g., an annulus shaped void or cavity). The ammonia stream 104 in the inner section 820b and the ammonia stream 104 in the outer section 820a may be in a counter flow configuration. The outer section 820a may be configured to receive the ammonia stream 104, and the inner section 820b may be configured to output the ammonia stream 104 (after the ammonia stream 104 is preheated).

[00415] In some cases, the NH3 preheating section 820 comprises an insulating material 854 that may line at least a portion of the reformer NH3 preheating section 820 (for example, a thermal coating that lines an outside surface of the NH3 preheating section 820on the wall separating the NH3 preheating section 820 from the combustion heater 109). The insulating material 854 may comprise a ceramic material, for example, alumina and/or silica based materials. In some cases, the insulating material 854 may cover less than about 50% of the surface area of the NH3 preheating section 820 (for example, the outer surface area of the NH3 preheating section 820 facing the combustion heater 109). In some cases, the insulating material covers less than about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% of the surface area of the NH3 preheating section 820. In some cases, the insulating material covers at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% of the surface area of the NH3 preheating section 820. The insulating material 854 may advantageously reduce the transfer of heat from the combustion exhaust 114 to a region of the NH3 preheating section 820 closer to the flame in the combustion heater 109 (for example, closer to the inlets for the reformate stream 120 and the air stream 118), thereby reducing thermal stress to the walls of the NH3 preheating section 820.

[00416] In some cases, the NH3 preheating section 820 comprises a heat exchanging element 805 configured to transfer heat from the combustion exhaust 114 to the ammonia stream 104 in the NH3 preheating section 820. The heat exchanging element 805 may comprise a helical feature (a wire or vane that winds around the NH3 preheating section 820). The pitch (period) of the helical feature 805 may be progressively smaller along a length of the NH3 preheating section 820, which may advantageously reduce the transfer of heat from the combustion exhaust 114 to a region of the NH3 preheating section 820 closer to the flame in the combustion heater 109 (for example, closer to the inlets for the reformate stream 120 and the air stream 118), thereby reducing thermal stress to the walls of the NH3 preheating section 820, and may advantageously increase heat transfer from the combustion exhaust 114 to a region of the NH3 preheating section 820 further from the flame in the combustion heater 109.

[00417] After the ammonia stream 104 is heated in the NH3 preheating section 820, the ammonia stream 104 may be reformed in the reformer 108 to generate the reformate stream 120 (by contacting the NH3 reforming catalyst 101a in the reformer 108). In some cases, the reformer 108 may at least partially surround the combustion heater 109 and/or the NH3 preheating section 820.

[00418] In some cases, an output conduit 823 may be positioned at least partially inside the reformer 108, and may be configured to receive the reformate stream 120, and output the reformate stream 120 from the reformer 108. The output conduit 823 may be an annulus or one or more tubes or channels (e.g., having a cylindrical or rectangular-cuboid shape). The output conduit 823 may be configured to transfer the reformate stream 120 from a first side of the reformer 108 to a second side of the reformer 108 opposite to the first side. For example, the output conduit 823 may be positioned so that the ammonia stream 104 contacts a majority of the particles of the catalyst 101 before the ammonia stream 104 enters the output conduit 823. The reformate stream 120 in the output conduit 823 and the ammonia stream 104 in the reformer 108 may be in a counter flow configuration, such that the reformate stream 120 travels in a first direction, and the ammonia stream 104 travels in a second direction opposite to the first direction.

[00419] In some cases, a cooling substance 825 may be configured to absorb heat from the reformate stream 120 exiting the reformer 108. The cooling substance 825 may comprise alumina, silica, silicon carbide, a metal (e.g., steel), or other conductive substance. The cooling substance 825 may comprise beads, pellets, spheres, or a monolith structure. The cooling substance 825 may be configured to transfer heat from the reformate stream 120 exiting the reformer 108 (e.g., via the transfer conduit or annulus 824a, the chamber 827, and the transfer conduit or annulus 824b) to the ammonia stream 104 entering the reformer 108 (e.g., from the NH3 preheating section 820).

[00420] A cooling chamber 827 may include the cooling substance 825 therein, and may separate the cooling substance 825 from the NH3 reforming catalyst 101a in the reformer 108. In some cases, the cooling chamber 827 may be a part of the same structure or housing of the reformerl08 (in other words, continuous and unitary with the housing of the reformer 108). In some cases, the cooling chamber 827 may be a separate structure or housing that is attached, secured or affixed to the reformer 108, and in some cases, may be slidably insertable and removable from the reformer 108.

[00421] As shown in FIG. 42C, a combustion heating section 830 may be configured to receive the combustion exhaust 114 (e.g., after the combustion exhaust 114 passes through the combustion heater 109 and transfers heat to the NH3 preheating section 820). The combustion heating section 830 may be in thermal communication with the reformer 108, and may be configured to transfer heat from the combustion exhaust 114 to the catalyst 101a in the reformer 108. This heat recovery may advantageously increase the ammonia conversion efficiency of the ammonia reforming reaction. In some cases, the combustion heating section 830 may at least partially surround the reformer 108 (as shown in FIG. 42C). In some cases, the combustion heating section 830 may be at least partially inside the reformer 108, for example, at least partially inside the bed of the catalyst 101a.

[00422] As shown in FIG. 42D, in some cases, the NH3 preheating section 820 further includes an NH3 injection section 820c in thermal communication with the combustion heater

109, and configured to transfer heat from the combustion exhaust 114 in the combustion heater 109 to the ammonia stream 104 in the NH3 injection section 820c. In some cases, a plurality of injection holes 871 may be positioned along a wall 870 separating the NH3 injection section 820c and the outer section 820a, and may be configured to inject the ammonia stream 104 into the NH3 injection section 820c such that the ammonia stream 104 impinges a surface of the wall separating the NH3 injection section 820c and the combustion heater 109.

[00423] As shown in FIGS. 42A-42D, the ammonia stream 104 may enter the top of the reformer 108, and travel down through the catalyst 101 to be reformed into the reformate stream 120. It is contemplated that, by directing the ammonia stream 104 in the same direction as gravity (for example, downward), fluidization (e.g., the formation of bubble pockets in the bed of the catalyst 101) may be prevented.

Computer Systems

[00424] The present disclosure provides computer systems (e.g., controllers, computing devices and/or computers) that are programmed to implement methods of the disclosure. FIG. 43 shows a computer system 901 that is programmed or otherwise configured to control the systems disclosed herein. The computer system 901 can regulate various aspects of the systems disclosed in the present disclosure. The computer system 901 can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

[00425] The computer system 901 includes a central processing unit (CPU, also “processor” and “computer processor” herein) 905, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 901 also includes memory or memory location 910 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 915 (e.g., hard disk), communication interface 920 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 925, such as cache, other memory, data storage and/or electronic display adapters. The memory 910, storage unit 915, interface 920 and peripheral devices 925 are in communication with the CPU 905 through a communication bus (solid lines), such as a motherboard. The storage unit 915 can be a data storage unit (or data repository) for storing data. The computer system 901 can be operatively coupled to a computer network (“network”) 930 with the aid of the communication interface 920. The network 930 can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network 930 in some cases is a telecommunication and/or data network. The network 930 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 930, in some cases with the aid of the computer system 901, can implement a peer-to- peer network, which may enable devices coupled to the computer system 901 to behave as a client or a server.

[00426] The CPU 905 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 910. The instructions can be directed to the CPU 905, which can subsequently program or otherwise configure the CPU 905 to implement methods of the present disclosure. Examples of operations performed by the CPU 905 can include fetch, decode, execute, and writeback.

[00427] The CPU 905 can be part of a circuit, such as an integrated circuit. One or more other components of the system 901 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[00428] The storage unit 915 can store files, such as drivers, libraries and saved programs. The storage unit 915 can store user data, e.g., user preferences and user programs. The computer system 901 in some cases can include one or more additional data storage units that are external to the computer system 901, such as located on a remote server that is in communication with the computer system 901 through an intranet or the Internet.

[00429] The computer system 901 can communicate with one or more remote computer systems through the network 930. For instance, the computer system 901 can communicate with a remote computer system of a user. Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system 901 via the network 930. [00430] Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 901, such as, for example, on the memory 910 or electronic storage unit 915. The machine executable or machine readable code can be provided in the form of software. During use, the code can be executed by the processor 905. In some cases, the code can be retrieved from the storage unit 915 and stored on the memory 910 for ready access by the processor 905. In some situations, the electronic storage unit 915 can be precluded, and machine-executable instructions are stored on memory 910.

[00431] The code can be pre-compiled and configured for use with a machine having a processer adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a precompiled or as-compiled fashion.

[00432] Aspects of the systems and methods provided herein, such as the computer system 901, can be embodied in programming. Various aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk.

“Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution.

[00433] Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include

-n- dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[00434] The computer system 901 can include or be in communication with an electronic display 935 that comprises a user interface (UI) 940 for providing. Examples of UI’s include, without limitation, a graphical user interface (GUI) and web-based user interface.

[00435] Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution by the central processing unit 905.

[00436] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby. Embodiments

[00437] Embodiment 1. An ammonia reforming system, comprising:

[00438] one or more storage tanks configured to store ammonia (NH3);

[00439] one or more electrically-heated reformers in fluid communication with the one or more storage tanks, wherein the one or more electrically-heated reformers comprise one or more first catalysts configured to reform the NH3 at a first target temperature range to generate a reformate stream comprising hydrogen (H2) and nitrogen (N2);

[00440] one or more electrical heaters configured to heat the one or more electrically- heated reformers to the first target temperature range;

[00441] one or more combustion-heated reformers in fluid communication with the one or more storage tanks, wherein the one or more combustion-heated reformers comprise one or more second catalysts configured to reform the NH3 at a second target temperature range to generate additional H2 and additional N2 for the reformate stream; and

[00442] one or more combustion heaters configured to combust the reformate stream to heat the one or more combustion-heated reformers.

[00443] Embodiment 2. The system of embodiment 1, wherein the one or more combustion heaters each comprise a flame tube, and the one or more combustion-heated reformers each comprise an inner shell and an outer shell,

[00444] wherein the flame tube, the inner shell, and the outer shell are concentrically aligned along a longitudinal axis so that the inner shell is adjacent to the flame tube, and the outer shell is adjacent to the inner shell.

[00445] Embodiment 3. The system of embodiment 2, further comprising one or more heat exchanging elements in at least one of the flame tube, the inner shell, or the outer shell, [00446] wherein the one or more heat exchanging elements are configured to transfer heat from a combustion product gas to the one or more catalysts of the one or more combustion- heated reformers.

[00447] Embodiment 4. The system of embodiment 3, wherein the one or more heat exchanging elements comprise at least one of:

[00448] one or more ceramic or metallic fins; or

[00449] one or more ceramic or metallic beads.

[00450] Embodiment 5. The system of embodiment 4, wherein a particle size of each of the one or more ceramic or metallic beads comprises of from about 0.1 millimeter (mm) to about 5 mm.

[00451] Embodiment 6. The system of embodiment 4, wherein the one or more ceramic or metallic fins comprise a vertical, a horizontal, a helical, or curved shape.

[00452] Embodiment 7. The system of embodiment 4, wherein the one or more ceramic or metallic fins comprising the helical or curved shape are positioned in the flame tube, to swirl the combustion product gas and thereby improve transfer of the heat to the one or more catalysts of the one or more combustion-heated reformers.

[00453] Embodiment 8. The system of embodiment 7, wherein the one or more ceramic or metallic fins comprising the helical or curved shape wrap around inner walls of the flame tube to swirl the combustion product gas.

[00454] Embodiment 9. The system of embodiment 3, wherein the one or more heat exchanging elements comprise at least one of

[00455] one or more ceramic or metallic honeycomb structures;

[00456] one or more ceramic or metallic meshes; or

[00457] one or more coiled springs.

[00458] Embodiment 10. The system of embodiment 3, wherein a coating of the one or more heat exchanging elements comprises the one or more catalysts of the one or more combustion-heated reformers.

[00459] Embodiment 11. The system of embodiment 2, wherein the flame tube, the inner shell, and the outer shell each comprise at least one of a metal or a ceramic.

[00460] Embodiment 12. The system of embodiment 11, wherein the metal comprises at least one of stainless steel, tungsten, titanium, or alloys thereof.

[00461] Embodiment 13. The system of embodiment 11, wherein the ceramic comprises at least one of alumina, silicon carbide or aluminum carbide.

[00462] Embodiment 14. The system of embodiment 2, wherein the flame tube, the inner shell, and the outer shell each comprise a length ranging of from about 0.2 meters to about 10 meters.

[00463] Embodiment 15. The system of embodiment 2, wherein walls of the flame tube, the inner shell, and the outer shell each comprise a thickness of from about 1 mm to about 10 cm. [00464] Embodiment 16. The system of embodiment 2, wherein an outer diameter of the inner shell, with respect to the longitudinal axis, comprises of from about 1.1 times an outer diameter of the flame tube to about 3 times the outer diameter of the flame tube.

[00465] Embodiment 17. The system of embodiment 2, wherein a ratio of a volume of the outer shell to a volume of the inner shell comprises of from about 1 : 1 to about 5: 1.

[00466] Embodiment 18. The system of embodiment 2, further comprising a preheating conduit in the flame tube, wherein the preheating conduit is concentrically aligned along the longitudinal axis.

[00467] Embodiment 19. The system of embodiment 18, wherein the preheating conduit is configured to transfer heat from (1) combustion product gas in the flame tube to (2) an incoming stream of the NH3 from the one or more storage tanks, so that the NH3 is preheated for decomposition in the one or more combustion-heated reformers or the one or more electrically- heated reformers.

[00468] Embodiment 20. The system of embodiment 18, wherein the preheating conduit is configured to transfer heat from (1) combustion product gas in the flame tube to (2) a stream of air, so that the air is preheated for the combustion in the flame tube.

[00469] Embodiment 21. The system of embodiment 18, wherein the preheating conduit, the one or more electrically-heated reformers and the one or more combustion-heated reformers are in fluid communication and configured so that an incoming stream of the NH3 passes the preheating conduit, then subsequently passes the one or more catalysts of the one or more electrically-heated reformers, and then subsequently passes the one or more catalysts of the one or more combustion-heated reformers.

[00470] Embodiment 22. The system of embodiment 18 or 20, wherein the preheating conduit comprises a plurality of injection holes along a length of the preheating conduit, wherein the plurality of injection holes are configured to inject air into the flame tube in a staged injection pattern.

[00471] Embodiment 23. The system of embodiment 22, wherein the plurality of injection holes are variably sized along the length of the flame tube to enable different injection velocities of the air into the flame tube.

[00472] Embodiment 24. The system of embodiment 22, wherein the plurality of injection holes are angled to improve mixing of the air and the reformate stream.

[00473] Embodiment 25. The system of embodiment 22, wherein the plurality of injection holes are positioned so that the air is injected tangentially with respect to a curved wall of the preheating conduit to swirl the air and improve mixing of the air and the reformate stream.

[00474] Embodiment 26. The system of embodiment 18, wherein a diameter of the preheating conduit comprises of from about 0.05 times an inner diameter of the flame tube to about 0.9 times the inner diameter of the flame tube.

[00475] Embodiment 27. The system of embodiment 18, wherein a length of the preheating conduit comprises of from about 0.75 times a length of the flame tube to about 2 times the length of the flame tube.

[00476] Embodiment 28. The system of embodiment 18, wherein a shape of the preheating conduit comprises a straight tube shape, a helical shape, a U shape, or a W shape.

[00477] Embodiment 29. The system of embodiment 2, wherein the one or more combustion heaters comprise a supply-tube configured for U-turn combustion,

[00478] wherein the supply tube is at least partially in the flame tube of the one or more combustion heaters,

[00479] wherein the supply tube comprises one or more inlets configured to receive the reformate stream and air,

[00480] wherein the one or more inlets are substantially adjacent to a first side of the one or combustion heaters,

[00481] wherein the supply tube comprises one or more outlets configured to direct the reformate stream and the air into the flame tube,

[00482] wherein the one or more outlets are substantially adjacent to a second side of the one or more combustion heaters, the second side being opposite to the first side; and

[00483] wherein the supply tube and the flame tube are configured in a U-turn combustion configuration so that the reformate stream and air pass through the supply tube along a first direction from the first side to the second side, and combustion product gas passes through the flame tube along a second direction from the second side to the first side.

[00484] Embodiment 30. The system of embodiment 29, wherein the supply tube comprises one or more reformate supply tubes and one or more air supply tubes, wherein the one or more reformate supply tubes and one or more air supply tubes have same diameters and lengths.

[00485] Embodiment 31. The system of embodiment 29, wherein the supply tube comprises one or more reformate supply tubes and one or more air supply tubes, wherein the one or more reformate supply tubes and the one or more air supply tubes have different diameters and lengths.

[00486] Embodiment 32. The system of embodiment 29, wherein the supply tube comprises one or more reformate supply tubes and one or more air supply tubes, wherein a length of each of the one or more reformate supply tubes and the one or more air supply tubes comprises of from about 0.1 to about 1 times the length of the supply tube.

[00487] Embodiment 33. The system of embodiment 1, wherein the one or more combustion heaters comprise a first inlet configured to receive a first reformate stream, and a second inlet configured to receive a second reformate stream.

[00488] Embodiment 34, wherein the first reformate stream comprises the reformate stream directed from at least one of the one or more electrically-heated reformers or the one or more combustion-heated reformers and

[00489] wherein the second reformate stream comprises the reformate stream directed from an outlet of one or more fuel cells.

[00490] Embodiment 35. The system of embodiment 34, wherein the first inlet and the second inlet are configured to separate the first reformate stream and the second reformate stream so that trace ammonia in the first reformate stream is prevented from flowing to the one or more fuel cells.

[00491] Embodiment 36. The system of embodiment 1, further comprising one or more heat exchangers.

[00492] Embodiment 37. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between one or more incoming streams of the NH3 from the one or more storage tanks and at least one of:

[00493] (a) the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers;

[00494] (b) the one or more combustion heaters;

[00495] (c) one or more combustion exhausts of the one or more combustion heaters;

[00496] (d) one or more adsorbents configured to filter out ammonia from the reformate stream;

[00497] (e) one or more fuel cells configured to generate electricity using at least part of the reformate stream; and

[00498] (f) one or more streams of air from one or more air supply units;

[00499] wherein exchanging the heat evaporates and/or preheats the one or more incoming streams of the NH3.

[00500] Embodiment 38. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers, and at least one of:

[00501] (a) one or more incoming streams of air from one or more air supply units; or

[00502] (b) one or more adsorbents configured to filter out ammonia from the reformate stream;

[00503] wherein exchanging the heat cools the reformate stream.

[00504] Embodiment 39. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between one or more adsorbents configured to filter out the ammonia from the reformate stream, and at least one of: [00505] (a) one or more electrical heaters;

[00506] (b) one or more combustion heaters;

[00507] (c) one or more combustion heaters of the one or more combustion heated reformers;

[00508] (d) one or more combustion exhausts of the one or more combustion heaters;

[00509] (e) the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers;

[00510] wherein exchanging the heat regenerates the one or more adsorbents or releases adsorbed ammonia from the one or more adsorbents.

[00511] Embodiment 40. The system of embodiment 39, wherein ammonia released from the one or more adsorbents is combusted in the one or more combustion heaters, filtered by one or more ammonia scrubbers, dissolved by a water tank, or vented to the atmosphere.

[00512] Embodiment 41. The system of embodiment 39, wherein one or more combustion exhausts of the one or more combustion-heated reformers are configured to exchange heat with the one or more adsorbents by at least one of:

[00513] (a) contacting combustion product gas with the one or more adsorbents;

[00514] (b) contacting combustion product gas with one or more heat exchanging elements, wherein the one or more heat exchanging elements are configured to transfer heat from the combustion product gas to the one or more adsorbents; or

[00515] (c) contacting combustion product gas with an intermediate fluid, wherein the intermediate fluid is configured to transfer heat from the combustion product gas to the one or more adsorbents.

[00516] Embodiment 42. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the one or more adsorbents configured to filter out the ammonia from one or more exit flows from the one or more reformers, and at least one of:

[00517] (a) one or more incoming streams of the NEE from the one or more storage tanks;

[00518] (b) one or more streams of air from one or more air supply units; or

[00519] (c) ambient air,

[00520] wherein exchanging the heat cools the one or more adsorbents.

[00521] Embodiment 43. The system of embodiment 42, wherein the one or more heat exchangers are configured to exchange heat between the one or more adsorbents and the ambient air using an intermediate fluid.

[00522] Embodiment 44. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the one or more incoming air flows from the one or more air supply units, and at least one of [00523] (a) the one or more combustion heaters;

[00524] (b) the one or more electrical heaters;

[00525] (c) the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers; and

[00526] (d) the one or more fuel cells configured to generate electricity from at least part of the reformate stream;

[00527] wherein exchanging the heat preheats the one or more streams of air from the one or more air supply units.

[00528] Embodiment 45. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the one or more storage tanks, and at least one of

[00529] (a) the one or more combustion heaters;

[00530] (b) the one or more electrical heaters;

[00531] (c) one or more combustion exhausts of the one or more combustion heaters;

[00532] (d) the reformate stream from at least one of the one or more combustion-heated reformers or the one or more electrically-heated reformers;

[00533] (e) ambient air;

[00534] (f) one or more streams of air from the one or more air supply units; and

[00535] (g) the one or more fuel cells configured to generate electricity from the at least part of the reformate stream;

[00536] wherein exchanging the heat evaporates the NH3 and/or increases a pressure of the one or more storage tanks.

[00537] Embodiment 46. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the one or more combustion heaters, and at least one of

[00538] (a) one or more incoming streams of the NH3 from the one or more storage tanks; and

[00539] (b) one or more incoming streams of air from one or more air supply units;

[00540] wherein exchanging the heat cools the one or more combustion heaters.

[00541] Embodiment 47. The system of embodiment 36, wherein the one or more heat exchangers are configured to exchange heat between the one or more fuel cells configured to generate electricity from the at least part of the reformate stream, and at least one of [00542] (a) one or more incoming streams of the NH3 from the one or more storage tanks;

[00543] (b) one or more incoming streams of air from the one or more air supply units; and

[00544] (c) ambient air;

[00545] wherein exchanging the heat cools the one or more fuel cells.

[00546] Embodiment 48. The system of embodiment 47, wherein the one or more heat exchangers are configured to exchange heat from the one or more fuel cells using an intermediate fluid.

[00547] Embodiment 49. The system of any of embodiment 36, wherein the one or more heat exchangers are configured in at least one of: a counter flow configuration, a cross flow configuration, or a parallel flow configuration.

[00548] Embodiment 50. The system of embodiment 36, further comprising one or more bluff bodies in the one or more combustion heaters, wherein the one or more bluff bodies are configured to absorb heat from combustion product gas in the one or more combustion heaters.

[00549] Embodiment 51. The system of embodiment 50, wherein a shape of a crosssection of the one or more bluff bodies comprises a circle, an ellipse, a square, a diamond, a triangle, or any combination thereof.

[00550] Embodiment 52. The system of embodiment 50, wherein the one or more bluff bodies comprise a metal or ceramic.

[00551] Embodiment 53. The system of embodiment 50, wherein a width of the one or more bluff bodies comprises of from about 0.1 to about 0.95 times an outer diameter of a flame tube of the one or more combustion heaters.

[00552] Embodiment 54. The system of embodiment 50, wherein a length of the one or more bluff bodies comprises of from about 0.05 to about 0.5 times a length of a flame tube of the one or more combustion heaters.

[00553] Embodiment 55. The system of embodiment 50, wherein the one or more bluff bodies are adjacent to an inlet of the one or more combustion heaters to cool the combustion product gas and reduce thermal stress on walls of the one or more combustion heaters.

[00554] Embodiment 56. The system of embodiment 50, wherein the one or more bluff bodies comprise one or more heat exchanging conduits configured to receive an incoming stream of the NH3 from the one or more storage tanks, wherein the heat exchanging conduits are configured to further absorb the heat from the combustion product gas to heat the incoming stream of the NH3.

[00555] Embodiment 57. The system of embodiment 56, wherein the one or more heat exchanging conduits comprise a helical shape or a serpentine shape to improve the absorption of the heat from the combustion product gas to heat the incoming stream of the NH3.

[00556] Embodiment 58. The system of embodiment 56, wherein the one or more heat exchanging conduits comprise one or more catalysts configured to decompose the incoming stream of the NH3.

[00557] Embodiment 59. The system of embodiment 56,

[00558] wherein each of the one or more combustion heaters include one or more preheating conduits,

[00559] wherein each of the one or more preheating conduits is concentrically aligned along a longitudinal axis of the one or more combustion heaters, and

[00560] wherein the one or more heat exchanging conduits of the one or more bluff bodies are in fluid communication with the one or more preheating conduits.

[00561] Embodiment 60. The system of embodiment 59, wherein the one or more preheating conduits of the one or more combustion heaters and the one or more heat exchanging conduits of the one or more bluff bodies are configured so that the incoming stream of the NH3 passes through the heat exchanging conduits, and then subsequently passes through the preheating conduit.

[00562] Embodiment 61. The system of embodiment 56,

[00563] wherein at least a portion of the one or more combustion heaters comprise hollow sidewalls in fluid communication with the heat exchanging conduits of the one or more bluff bodies, and

[00564] wherein the hollow sidewalls are configured to receive an incoming stream of the NH3 from the one or more storage tanks to preheat the incoming stream of the NH3, before the incoming stream of the NH3 passes through the heat exchanging conduits of the one or more bluff bodies.

[00565] Embodiment 62. The system of embodiment 56,

[00566] wherein at least a portion of the one or more combustion heaters comprise hollow sidewalls in fluid communication with one or more air supply units configured to provide air to the hollow sidewalls,

[00567] wherein the hollow sidewalls comprise a plurality of injection holes adjacent to inside the one or more combustion heaters, and

[00568] wherein the plurality of injection holes are configured to inject the air into inside the one or more combustion heaters in a staged injection pattern.

[00569] Embodiment 63. The system of embodiment 56, wherein the portion including the hollow sidewalls comprising the plurality of injection holes is adjacent to an inlet of the one or more combustion heaters to cool the combustion product gas and reduce thermal stress on walls of the one or more combustion heaters, and to preheat the air for combustion in the one or more combustion heaters.

[00570] Embodiment 64. The system of embodiment 1, further comprising fluidized particles in the one or more combustion heaters, wherein the fluidized particles are configured to transfer heat from (1) combustion product gas in the one or more combustion heaters to (2) the one or more catalysts of the one or more combustion-heated reformers.

[00571] Embodiment 65. The system of embodiment 64, further comprising a fluidization funnel positioned adjacent to an inlet of the one or more combustion heaters,

[00572] wherein the fluidization funnel is configured to receive or hold the fluidized particles,

[00573] wherein the inlet is configured to receive one or more streams comprising at least one of the hydrogen or air; and

[00574] wherein the fluidization funnel is configured to be in fluid communication with the inlet, so that when the one or more streams pass the fluidization funnel, the one or more streams push the fluidized particles into the one or more combustion heaters to absorb heat from the combustion product gas and transfer the heat to the one or more catalysts of the one or more combustion-heated reformers.

[00575] Embodiment 66. The system of embodiment 64, wherein the fluidized particles comprise at least one of sand, ceramic particles, or metallic particles.

[00576] Embodiment 67. The system of embodiment 64, wherein a particle size of each of the fluidized particles comprises at least about 100 microns.

[00577] Embodiment 68. The system of embodiment 64, wherein a particle size of each of the fluidized particles comprises at most about 2 millimeters.

[00578] Embodiment 69. The system of embodiment 64, further comprising a grated or perforated plate in or at a combustion exhaust of the one or more combustion heaters, wherein the grated or perforated plate is configured to prevent escape of the fluidized particles from the one or more combustion heaters.

[00579] Embodiment 70. The system of embodiment 1, further comprising one or more water collection devices in fluid communication with one or more combustion exhausts of the one or more combustion heaters, wherein the one or more water collection devices are configured to remove water from combustion product gas.

[00580] Embodiment 71. The system of embodiment 70, further comprising a water collection tank configured to store the water removed from the combustion product gas.

[00581] Embodiment 72. The system of embodiment 71, further comprising one or more electrolyzers configured to electrolyze the stored water removed from the combustion product gas to generate additional hydrogen (EE).

[00582] Embodiment 73. The system of embodiment 71, further comprising one or more fuel cells configured to generate electricity from the at least part of the generated hydrogen from at least one of the one or more combustion-heated reformers or the one or more electrically- heated reformers,

[00583] wherein an inlet of the one or more fuel cells is configured to be in fluid communication with the water collection tank so that the water humidifies the one or more fuel cells; or

[00584] wherein an outlet of the one or more fuel cells is configured to be in fluid communication with the water collection tank so that the water is collected in the water collection tank from the outlet of the one or more fuel cells.

[00585] Embodiment 74. The system of embodiment 1, further comprising one or more thermoelectric generators in fluid communication with one or more combustion exhausts of the one or more combustion heaters, wherein the one or more thermoelectric generators are configured to generate electricity using heat of combustion product gas.

[00586] Embodiment 75. The system of embodiment 74, further comprising a compressor in fluid communication with an inlet of the one or more combustion heaters,

[00587] wherein the compressor is configured to compress air and provide the compressed air to the one or more combustion heaters for combustion; and

[00588] wherein the compressor is configured to be powered using the electricity generated by the one or more thermoelectric generators.

[00589] Embodiment 76. The system of embodiment 1, further comprising one or more turbochargers or turbines in fluid communication with one or more combustion exhausts of the one or more combustion heaters, wherein the one or more turbochargers or turbines are configured to be driven using combustion product gas to compress air.

[00590] Embodiment 77. The system of embodiment 76, wherein the one or more turbochargers or turbines are in fluid communication with an inlet of the one or more combustion heaters; and

[00591] wherein the one or more turbochargers are configured to provide the compressed air to the one or more combustion heaters for combustion.

[00592] Embodiment 78. The system of embodiment 1, wherein the one or more combustion heaters comprise a burner head including one or more primary air inlets configured to receive a primary air stream, and one or more reformate inlets configured to receive the reformate stream.

[00593] Embodiment 79. The system of embodiment 78,

[00594] wherein an air preheating channel is positioned in the burner head,

[00595] wherein the air preheating channel includes a secondary inlet configured to receive a secondary air stream, and

[00596] wherein the secondary air stream cools the one or more combustion heaters at, near or adjacent to the burner heard.

[00597] Embodiment 80. The system of embodiment 79, wherein the air preheating channel includes a plurality of injection holes along a length of the air preheating channel and [00598] wherein the plurality of injection holes are configured to inject the secondary air stream into the one or more combustion heaters.

[00599] Embodiment 81. The system of embodiment 78, wherein the secondary inlet is further configured to receive a mixture of (1) the secondary air stream and (2) the reformate stream.

[00600] Embodiment 82. The system of embodiment 78,

[00601] wherein an NEE preheating channel is positioned in the burner head,

[00602] wherein the NEE preheating channel includes an inlet configured to receive an incoming NEE stream, and

[00603] wherein the incoming NEE stream cools the one or more combustion heaters at, near or adjacent to the burner head.

[00604] Embodiment 83. The system of embodiment 82,

[00605] wherein the incoming NEE stream, after being preheated in the NEE preheating channel, is configured to be directed to the one or more combustion-heated reformers or the one or more electrically-heated reformers for decomposition.

[00606] Embodiment 84. The system of embodiment 1, wherein the one or more combustion heaters comprise inner sidewalls, outer sidewalls, and a copper layer between the inner sidewalls and the outer sidewalls, wherein the copper layer is configured to evenly distribute heat from combustion product gas in the one or more combustion heaters to the one or more catalysts of the one or more combustion-heated reformers.

[00607] Embodiment 85. The system of any of embodiments 1 to 84, further comprising one or more adsorbents configured to remove the ammonia from the reformate stream, wherein regeneration of the one or more adsorbents is initiated when a measured temperature of the one or more adsorbents is equal to or greater than a threshold adsorbent temperature.

[00608] Embodiment 86. The system of embodiment 85, wherein the measured temperature of the one or more adsorbents is measured at, in, or adjacent to at least one of: [00609] (1) an inlet of the one or more adsorbents,

[00610] (2) an outlet of the one or more adsorbents,

[00611] (3) between the inlet and the outlet, or

[00612] (4) a filtered reformate stream output from the one or more adsorbents.

[00613] Embodiment 87. The system of embodiment 85 or 86, wherein the threshold adsorbent temperature is at least about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than an ambient temperature.

[00614] Embodiment 88. The system of embodiment 85 or 86, wherein the threshold adsorbent temperature is at most about 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 °C higher than an ambient temperature.

[00615] Embodiment 89. The system of any of embodiments 1 to 88, wherein the first catalyst and the second catalyst are same.

[00616] Embodiment 90. A furnace ammonia reforming system, comprising:

[00617] one or more storage tanks configured to store ammonia (NEE);

[00618] a furnace comprising one or more reformers, wherein the one or more reformers comprise one or more catalysts configured to decompose the NEE to generate hydrogen (EE) and nitrogen (N2);

[00619] one or more burners in or in fluid communication with the furnace configured to combust a fuel to heat the furnace;

[00620] an inlet manifold configured to direct the NEE from the one or more storage tanks to the one or more reformers; and

[00621] an outlet manifold configured to direct the E and the N2 out of the one or more reformers.

[00622] Embodiment 91. The system of embodiment 90,

[00623] wherein each of the one or more reformers includes an inner chamber and an outer chamber comprising the one or more catalysts;

[00624] wherein the inner chamber is in fluid communication with the inlet manifold, and the outer chamber is in fluid communication with the outlet manifold; and

[00625] wherein the inner chamber and the outer chamber are configured so that, to increase a contact time of the NEE with the one or more catalysts and/or increase heat transfer between the inner chamber and outer chamber, the NEE passes the inner chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the outer chamber along a second direction from the second side to the first side.

[00626] Embodiment 92. The system of embodiment 90,

[00627] wherein each of the one or more reformers includes an inner chamber and an outer chamber comprising the one or more catalysts;

[00628] wherein the inner chamber is in fluid communication with the outlet manifold, and the outer chamber is in fluid communication with the inlet manifold; and

[00629] wherein the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outlet chamber, the NH3 passes the outer chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the inner chamber along a second direction from the second side to the first side.

[00630] Embodiment 93. The system of embodiment 90, further comprising a convective heat exchanger in fluid communication with the furnace chamber and configured to receive combustion product gas from the one or more burners,

[00631] wherein the convective heat exchanger is configured to transfer heat from the combustion product gas to an incoming stream of the NH3 from the one or more storage tanks to evaporate and/or preheat the incoming stream of the NH3.

[00632] Embodiment 94. The system of embodiment 90, wherein the one or more reformers comprise one or more U-shaped reformers.

[00633] Embodiment 95. The system of embodiment 94, wherein the one or more U- shaped reformers each comprise a bend.

[00634] Embodiment 96. The system of embodiment 94, wherein the furnace comprises a partition configured to divide the furnace into a first chamber and a second chamber.

[00635] Embodiment 97. The system of embodiment 94,

[00636] wherein each of the one or more U-shaped reformers includes an inner chamber and an outer chamber comprising the one or more catalysts;

[00637] wherein the inner chamber is in fluid communication with the inlet manifold, and the outer chamber is in fluid communication with the outlet manifold; and

[00638] wherein the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outer chamber, the NH3 passes the inner chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the outer chamber along a second direction from the second side to the first side.

[00639] Embodiment 98. The system of embodiment 94,

[00640] wherein each of the one or more U-shaped reformers includes an inner chamber and an outer chamber comprising the one or more catalysts;

[00641] wherein the inner chamber is in fluid communication with the outlet manifold, and the outer chamber is in fluid communication with the inlet manifold; and

[00642] wherein the inner chamber and the outer chamber are configured so that, to increase a contact time of the NH3 with the one or more catalysts and/or increase heat transfer between the inner chamber and outlet chamber, the NH3 passes the outer chamber along a first direction from a first side of the respective one or more reformers to a second side of the respective one or more reformers opposite to the first side, and so that the NH3 subsequently passes the inner chamber along a second direction from the second side to the first side.

[00643] Embodiment 99. A heat exchanger reformer comprising:

[00644] one or more reaction channels in fluid communication with an ammonia reformer configured to decompose ammonia using one or more catalysts; and

[00645] wherein the one or more reaction channels comprise one or more extended or corrugated surfaces coated or filled with the one or more catalysts configured to decompose the ammonia;

[00646] one or more heat exchanging channels with one or more extended or corrugated surfaces configured to transfer heat from a fluid stream to the one or more reaction channels.

[00647] Embodiment 100. The heat exchanger reformer of embodiment 99, wherein a spacing between one or more extended or corrugated surfaces comprises: at least about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm.

[00648] Embodiment 101. The heat exchanger reformer of embodiment 99, wherein a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm.

[00649] Embodiment 102. The heat exchanger reformer of embodiment 99, wherein a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm. [00650] Embodiment 103. The heat exchanger reformer of embodiment 99, wherein a spacing between one or more extended or corrugated surfaces comprises: at most about 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm.

[00651] Embodiment 104. The heat exchanger reformer of embodiment 99, wherein the heat exchanger reformer comprises at least one of plate-type heat exchanger, shell-and-tube type heat exchanger, or tube-in-tube type heat exchanger.

[00652] Embodiment 105. The heat exchanger reformer of any of embodiments 99 to 104, wherein the one or more reaction channels and/or the one or more heat exchanging channels comprise one or more metal meshes configured to improve transfer of the heat.

[00653] Embodiment 106. The heat exchanger reformer of any of embodiments 100 to

105, wherein a portion of the heat exchanger is configured to evaporate or preheat an incoming stream of the ammonia.

[00654] Embodiment 107. The heat exchanger reformer of any of embodiments 100 to

106, wherein the one or more catalysts comprise at least one of:

[00655] ruthenium or nickel as an active metal; and/or

[00656] an active metal comprising a diameter of at least about 1 nm, 10 nm, 100 nm, or 1000 nm.

[00657] Embodiment 108. The heat exchanger reformer of embodiment 107, wherein the active metal comprising a diameter of at most about 1 nm, 10 nm, 100 nm, or 1000 nm.

[00658] Embodiment 109. A multi-channel reformer comprising:

[00659] a housing comprising a plurality of inner shells and at least one outer shell:

[00660] one or more heating elements embedded in each of the plurality of inner shells; and

[00661] an ammonia (NH3) reforming catalyst in at least one of the plurality of inner shells or the at least one outer shell.

[00662] Embodiment 110. The multi-channel reformer of embodiment 109, wherein the housing comprises a rectangular cross-sectional shape.

[00663] Embodiment 111. The multi-channel reformer of embodiment 109, wherein the housing comprises a circular cross-sectional shape.

[00664] Embodiment 112. A method comprising reforming ammonia using the system of any of the embodiments 1-111.

[00665] Embodiment 113. A method comprising converting ammonia into electrical power using the system of any of embodiments 1-111. [00666] Embodiment 114. A method comprising converting ammonia into hydrogen using the system of any of embodiments 1-111.

[00667] Embodiment 115. An ammonia reforming system, comprising:

[00668] a first reformer configured to reform ammonia to generate a first reformate stream comprising hydrogen and nitrogen; and

[00669] a combustion heater configured to combust a first portion of the first reformate stream and generate a combustion exhaust to heat the first reformer

[00670] Embodiment 116. The system of embodiment 115, further comprising a second reformer configured to generate a second reformate stream comprising hydrogen and nitrogen, wherein the combustion heater is configured to combust the second reformate stream to heat the first reformer.

[00671] Embodiment 117. The system of embodiment 115, wherein the first reformer comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[00672] Embodiment 118. The system of embodiment 117, wherein the heat exchanging element comprises a helical feature.

[00673] Embodiment 119. The system of embodiment 118, wherein the helical feature comprises a wire or a vane.

[00674] Embodiment 120. The system of embodiment 115, wherein the first reformer and the combustion heater are aligned concentrically along a longitudinal axis.

[00675] Embodiment 121. The system of embodiment 115, wherein the combustion heater at least partially surrounds the first reformer.

[00676] Embodiment 122. The system of embodiment 115, wherein the first reformer includes an inner shell and an outer shell.

[00677] Embodiment 123. The system of embodiment 122, wherein the outer shell at least partially surrounds the inner shell.

[00678] Embodiment 124. The system of embodiment 122, wherein the combustion heater at least partially surrounds the outer shell.

[00679] Embodiment 125. The system of embodiment 122, wherein the combustion heater, the inner shell, and the outer shell are aligned along a longitudinal axis.

[00680] Embodiment 126. The system of embodiment 125, wherein a first radial distance of the inner shell with respect to the longitudinal axis is smaller than a second radial distance of the outer shell with respect to the longitudinal axis, so that the outer shell extends further from the longitudinal axis compared to the inner shell. [00681] Embodiment 127. The system of embodiment 125, wherein a second radial distance of the outer shell with respect to the longitudinal axis is smaller than a third radial distance of the combustion heater with respect to the longitudinal axis, so that the combustion heater extends further from the longitudinal axis compared to the outer shell.

[00682] Embodiment 128. The system of embodiment 122, further comprising a blockage structure positioned in the inner shell.

[00683] Embodiment 129. The system of embodiment 128, wherein the blockage structure has a cylindrical or rectangular cuboid shape.

[00684] Embodiment 130. The system of embodiment 128, wherein the blockage structure comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[00685] Embodiment 131. The system of embodiment 130, wherein the heat exchanging element comprises a helical feature.

[00686] Embodiment 132. The system of embodiment 131, wherein the helical feature comprises a wire or a vane.

[00687] Embodiment 133. The system of embodiment 115, further comprising a refractory fiber material on an inner surface of the combustion heater.

[00688] Embodiment 134. The system of embodiment 115, further comprising a metal lining on an inner surface of the combustion heater.

[00689] Embodiment 135. The system of embodiment 115, further comprising an insulating material on an outer surface of the first reformer.

[00690] Embodiment 136. The system of embodiment 135, wherein the insulating material covers less than half a surface area of the first reformer.

[00691] Embodiment 137. The system of embodiment 115, wherein the combustion heater comprises a primary air inlet configured to receive a primary air stream, a reformate inlet configured to receive the first reformate stream, and secondary air inlet configured to receive a secondary air stream.

[00692] Embodiment 138. The system of embodiment 137, wherein the primary air inlet and the reformate inlet form an annulus, and the secondary air inlet is positioned at a center of the annulus.

[00693] Embodiment 139. The method of embodiment 137, wherein the secondary air inlet comprises a cylindrical conduit.

[00694] Embodiment 140. The method of embodiment 137, wherein the secondary inlet is further configured to receive a mixture of the secondary air stream and the first reformate stream. [00695] Embodiment 141. The system of embodiment 115, further comprising an air preheating section at least partially surrounding the combustion heater configured to receive an air stream.

[00696] Embodiment 142. The system of embodiment 141, wherein the air preheating section forms an annulus.

[00697] Embodiment 143. The system of embodiment 141, wherein the air preheating section is in thermal communication with the combustion heater, and configured so that the combustion exhaust in the combustion heater transfers heat to the air stream in the air preheating section.

[00698] Embodiment 144. The system of embodiment 141, wherein the air stream in the air preheating section and the combustion exhaust in the combustion heater are arranged in a counter flow configuration.

[00699] Embodiment 145. The system of embodiment 141, further comprising a plurality of injection holes configured to inject the air stream into the combustion heater and toward the first reformer from the air preheating section.

[00700] Embodiment 146. The system of embodiment 145, wherein the injection holes are positioned along a wall separating the air preheating section and the combustion heater.

[00701] Embodiment 147. The system of embodiment 145, wherein the injection holes are variably sized along a length of the combustion heater.

[00702] Embodiment 148. The system of embodiment 147, wherein the injection holes are progressively smaller along the length of the combustion heater.

[00703] Embodiment 149. The system of embodiment 115, further comprising a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

[00704] Embodiment 150. The system of embodiment 149, wherein the heat exchanging element comprises a helical feature.

[00705] Embodiment 151. The system of embodiment 150, wherein the helical feature winds around an outer surface of the first reformer.

[00706] Embodiment 152. The system of embodiment 150, wherein the helical feature winds around an inner surface of the first reformer.

[00707] Embodiment 153. The system of embodiment 150, wherein the helical feature comprises a wire or a vane.

[00708] Embodiment 154. The system of embodiment 115, further comprising a combustion heating section configured to receive the combustion exhaust from the combustion heater, wherein the combustion heating section is in thermal communication with the first reformer.

[00709] Embodiment 155. The system of embodiment 154, wherein the combustion heater and the combustion heating section are separate structures.

[00710] Embodiment 156. The system of embodiment 154, wherein the combustion heater is configured to be attached to and detached from the combustion heating section.

[00711] Embodiment 157. The system of embodiment 115, wherein the combustion heater and the first reformer are separate structures.

[00712] Embodiment 158. The system of embodiment 115, wherein the combustion heater is configured to be attached to and detached from the first reformer.

[00713] Embodiment 159. The system of embodiment 115, wherein the combustion heater is configured so that a flame produced by the combustion heater does not impinge the first reformer.

[00714] Embodiment 160. The system of embodiment 154, further comprising a partition in the combustion heating section, wherein the partition includes a plurality of injection ports configured to inject the combustion exhaust toward the first reformer .

[00715] Embodiment 161. The system of embodiment 154, further comprising an exhaust conduit configured to transfer the combustion exhaust from the combustion heater to the combustion heating section .

[00716] Embodiment 162. The system of embodiment 161, wherein the exhaust conduit includes a plurality of injection holes configured to inject the combustion exhaust into the combustion heating section and toward the first reformer .

[00717] Embodiment 163. The system of embodiment 162, wherein the injection holes are variably sized along a length of the exhaust conduit.

[00718] Embodiment 164. The system of embodiment 162, wherein the injection holes are progressively smaller along the length of the exhaust conduit.

[00719] Embodiment 165. The system of embodiment 154, wherein the first reformer includes an inner shell and an outer shell.

[00720] Embodiment 166. The system of embodiment 165, wherein the first reformer is configured so that the first reformate stream travels in a U-turn path between the outer shell and the inner shell.

[00721] Embodiment 167. The system of embodiment 165, wherein the combustion heating section is configured so that the combustion exhaust contacts a wall of the inner shell to transfer heat to the inner shell. [00722] Embodiment 168. The system of embodiment 167, wherein the combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the outer shell to transfer heat to the outer shell after contacting the wall of the inner shell.

[00723] Embodiment 169. The system of embodiment 165, wherein the combustion heating section is configured so that the combustion exhaust contacts a wall of the outer shell to transfer heat to the outer shell .

[00724] Embodiment 170. The system of embodiment 169, wherein the combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the inner shell to transfer heat to the inner shell after contacting the wall of the outer shell.

[00725] Embodiment 171. The system of embodiment 154, further comprising an air preheating section at least partially surrounding the combustion heating section configured to receive an air stream .

[00726] Embodiment 172. The system of embodiment 171, wherein the air preheating section forms an annulus.

[00727] Embodiment 173. The system of embodiment 171, wherein the air preheating section is in thermal communication with the combustion heating section, and configured so that the combustion exhaust in the combustion heating section transfers heat to the air stream in the air preheating section.

[00728] Embodiment 174. The system of embodiment 171, wherein the air stream in the air preheating section and the combustion exhaust in the combustion heating section are arranged in a counter flow configuration.

[00729] Embodiment 175. The system of embodiment 115, further comprising an NH3 preheating section configured to receive the ammonia before the ammonia is reformed in the first reformer.

[00730] Embodiment 176. The system of embodiment 175, wherein the NH3 preheating section is in thermal communication with the combustion heater, and is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 preheating section.

[00731] Embodiment 177. The system of embodiment 115, further comprising a combustion heating section configured to receive the combustion exhaust after the combustion exhaust passes through the combustion heater.

[00732] Embodiment 178. The system of embodiment 177, wherein the combustion heating section is in thermal communication with the first reformer, and is configured to transfer heat from the combustion exhaust to the first reformer. [00733] Embodiment 179. The system of embodiment 177, wherein the combustion heating section at least partially surrounds the first reformer .

[00734] Embodiment 180. The system of embodiment 175, wherein the NH3 preheating section at least partially surrounds the combustion heater.

[00735] Embodiment 181. The system of embodiment 175, wherein the combustion heater at least partially surrounds the NH3 preheating section.

[00736] Embodiment 182. The system of embodiment 175, wherein the NH3 preheating section includes an inner section and an outer section .

[00737] Embodiment 183. The system of embodiment 182, wherein the inner section is a cylindrical conduit, and the outer section is an annulus.

[00738] Embodiment 184. The system of embodiment 182, wherein the ammonia in the inner section and the ammonia in the outer section are in a counter flow configuration.

[00739] Embodiment 185. The system of embodiment 182, wherein the outer section is configured to receive the ammonia stream, and the inner section is configured to output the ammonia stream.

[00740] Embodiment 186. The system of embodiment 182, wherein the NH3 preheating section further includes an NH3 injection section in thermal communication with the combustion heater, wherein the NH3 injection section is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 injection section.

[00741] Embodiment 187. The system of embodiment 186, further comprising a plurality of injection holes along a wall separating the NH3 injection section and the outer section, and configured to inject the ammonia into the NH3 injection section and toward the combustion heater .

[00742] Embodiment 188. The system of embodiment 175, wherein the NH3 preheating section comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the ammonia in the preheating section.

[00743] Embodiment 189. The system of embodiment 188, wherein the heat exchanging element comprises a helical feature.

[00744] Embodiment 190. The system of embodiment 189, wherein the helical feature winds around the NH3 preheating section.

[00745] Embodiment 191. The system of embodiment 189, wherein the helical feature comprises a wire or a vane.

[00746] Embodiment 192. The system of embodiment 189, wherein the helical feature has a pitch that varies. [00747] Embodiment 193. The system of embodiment 192, wherein the pitch of the helical feature is progressively smaller along a length of the NH3 preheating section.

[00748] Embodiment 194. The system of embodiment 175, wherein the first reformer at least partially surrounds the NH3 preheating section.

[00749] Embodiment 195. The system of embodiment 175, wherein the first reformer at least partially surrounds the combustion heater and the preheating section.

[00750] Embodiment 196. The system of embodiment 115, further comprising an output conduit at least partially inside the first reformer configured to receive the first reformate stream . [00751] Embodiment 197. The system of embodiment 196, wherein the output conduit is configured to transfer the first reformate stream from a first side of the first reformer to a second side of the first reformer opposite to the first side.

[00752] Embodiment 198. The system of embodiment 115, further comprising a cooling substance configured to absorb heat from the first reformate stream.

[00753] Embodiment 199. The system of embodiment 198, further comprising a cooling chamber including the cooling substance therein, wherein the cooling chamber separates the cooling substance from an NH3 reforming catalyst in the first reformer .

[00754] Embodiment 200. The system of embodiment 199, further comprising a transfer conduit at least partially inside the first reformer configured to receive the first reformate stream, wherein the transfer conduit is configured to transfer the first reformate stream from the NH3 reforming catalyst to the cooling substance in the cooling chamber.

[00755] Embodiment 201. The system of embodiment 199, wherein the cooling substance comprises a ceramic or a metal.

[00756] Embodiment 202. The system of embodiment 199, wherein the cooling substance comprises beads or pellets.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. An ammonia reforming system, comprising: a first reformer configured to reform ammonia to generate a first reformate stream comprising hydrogen and nitrogen; and a combustion heater configured to combust a first portion of the first reformate stream and generate a combustion exhaust to heat the first reformer.

2. The system of claim 1, further comprising a second reformer configured to generate a second reformate stream comprising hydrogen and nitrogen, wherein the combustion heater is configured to combust the second reformate stream to heat the first reformer.

3. The system of any one of claims 1-2, wherein the first reformer comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

4. The system of claim 3, wherein the heat exchanging element comprises a helical feature.

5. The system of claim 4, wherein the helical feature comprises a wire or a vane.

6. The system of any one of claims 4-5, wherein the helical feature winds around an outer surface of the first reformer.

7. The system of any one of claims 3-6, wherein the helical feature winds around an inner surface of the first reformer.

8. The system of any one of claims 1-7, wherein the first reformer and the combustion heater are aligned concentrically along a longitudinal axis.

9. The system of any one of claims 1-8, wherein the combustion heater at least partially surrounds the first reformer.

10. The system of any one of claims 1-9, wherein the first reformer comprises an inner shell and an outer shell.

11. The system of claim 10, wherein the outer shell at least partially surrounds the inner shell.

12. The system of any one of claims 9-11, wherein the combustion heater at least partially surrounds the outer shell.

13. The system of any one of claims 10-12, wherein the combustion heater, the inner shell, and the outer shell are aligned along a longitudinal axis.

14. The system of any one of claims 10-13, wherein a first radial distance of the inner shell with respect to the longitudinal axis is smaller than a second radial distance of the outer shell with respect to the longitudinal axis, so that the outer shell extends further from the longitudinal axis compared to the inner shell.

15. The system of any one of claims 10-14, wherein a second radial distance of the outer shell with respect to the longitudinal axis is smaller than a third radial distance of the combustion heater with respect to the longitudinal axis, so that the combustion heater extends further from the longitudinal axis compared to the outer shell.

16. The system of any one of claims 10-15, further comprising a blockage structure positioned in the inner shell.

17. The system of claim 16, wherein the blockage structure has a cylindrical or rectangular cuboid shape.

18. The system of any one of claims 16-17, wherein the blockage structure comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the first reformer.

19. The system of claim 18, wherein the heat exchanging element comprises a helical feature.

20. The system of claim 19, wherein the helical feature comprises a wire or a vane.

21. The system of any one of claims 1-20, further comprising a refractory fiber material on an inner surface of the combustion heater.

22. The system of any one of claims 1-21, further comprising a metal lining on an inner surface of the combustion heater.

23. The system of any one of claims 1-22, further comprising an insulating material on an outer surface of the first reformer.

24. The system of claim 23, wherein the insulating material covers less than half a surface area of the first reformer.

25. The system of any one of claims 1-24, wherein the combustion heater comprises a primary air inlet configured to receive a primary air stream, a reformate inlet configured to receive the first reformate stream, and a secondary air inlet configured to receive a secondary air stream.

26. The system of claim 25, wherein the primary air inlet and the reformate inlet form an annulus, and the secondary air inlet is positioned at a center of the annulus.

27. The method of any one of claims 25-26, wherein the secondary air inlet comprises a cylindrical conduit.

28. The method of any one of claims 25-27, wherein the secondary inlet is further configured to receive a mixture of the secondary air stream and the first reformate stream.

29. The system of any one of claims 1-28, further comprising an air preheating section at least partially surrounding the combustion heater configured to receive an air stream.

30. The system of claim 29, wherein the air preheating section forms an annulus.

31. The system of any one of claims 29-30, wherein the air preheating section is in thermal communication with the combustion heater, and configured so that the combustion exhaust in the combustion heater transfers heat to the air stream in the air preheating section.

32. The system of any one of claims 29-31, wherein the air stream in the air preheating section and the combustion exhaust in the combustion heater are arranged in a counter flow configuration.

33. The system of any one of claims 29-32, further comprising a plurality of injection holes configured to inject the air stream into the combustion heater and toward the first reformer from the air preheating section.

34. The system of any one of claims 29-33, wherein the injection holes are positioned along a wall separating the air preheating section and the combustion heater.

35. The system of any one of claims 29-34, wherein the injection holes are variably sized along a length of the combustion heater.

36. The system of any one of claims 29-35, wherein the injection holes are progressively smaller along the length of the combustion heater.

37. The system of any one of claims 1-36, further comprising a combustion heating section configured to receive the combustion exhaust from the combustion heater, wherein the combustion heating section is in thermal communication with the first reformer.

38. The system of claim 37, wherein the combustion heater and the combustion heating section are separate structures.

39. The system of any one of claims 37-38, wherein the combustion heater is configured to be attached to and detached from the combustion heating section.

40. The system of any one of claims 37-39, wherein the combustion heater and the first reformer are separate structures.

41. The system of any one of claims 37-40, wherein the combustion heater is configured to be attached to and detached from the first reformer.

42. The system of any one of claims 37-41, wherein the combustion heater is configured so that a flame produced by the combustion heater does not impinge the first reformer.

43. The system of any one of claims 37-42, further comprising a partition in the combustion heating section, wherein the partition comprises a plurality of injection ports configured to inject the combustion exhaust toward the first reformer.

44. The system of any one of claims 37-43, further comprising an exhaust conduit configured to transfer the combustion exhaust from the combustion heater to the combustion heating section.

45. The system of claim 44, wherein the exhaust conduit comprises a plurality of injection holes configured to inject the combustion exhaust into the combustion heating section and toward the first reformer.

46. The system of claim 45, wherein the plurality of injection holes are variably sized along a length of the exhaust conduit.

47. The system of any one of claims 45-46, wherein the plurality of injection holes are progressively smaller along the length of the exhaust conduit.

48. The system of any one of claims 37-47, wherein the first reformer comprises an inner shell and an outer shell.

49. The system of claim 48, wherein the first reformer is configured so that the first reformate stream travels in a U-turn path between the outer shell and the inner shell.

50. The system of any one of claims 48-49, wherein the combustion heating section is configured so that the combustion exhaust contacts a wall of the inner shell to transfer heat to the inner shell.

51. The system of claim 50, wherein the combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the outer shell to transfer heat to the outer shell after contacting the wall of the inner shell.

52. The system of any one of claims 48-49, wherein the combustion heating section is configured so that the combustion exhaust contacts a wall of the outer shell to transfer heat to the outer shell.

53. The system of claim 52, wherein the combustion heating section is configured so that the combustion exhaust subsequently contacts a wall of the inner shell to transfer heat to the inner shell after contacting the wall of the outer shell.

54. The system of any one of claims 37-53, further comprising an air preheating section at least partially surrounding the combustion heating section configured to receive an air stream.

55. The system of claim 54, wherein the air preheating section forms an annulus.

56. The system of any one of claims 54-55, wherein the air preheating section is in thermal communication with the combustion heating section, and configured so that the combustion exhaust in the combustion heating section transfers heat to the air stream in the air preheating section.

57. The system of any one of claims 54-56, wherein the air stream in the air preheating section and the combustion exhaust in the combustion heating section are arranged in a counter flow configuration.

58. The system of any one of claims 1-57, further comprising an NH3 preheating section configured to receive the ammonia before the ammonia is reformed in the first reformer.

59. The system of claim 58, wherein the NH3 preheating section is in thermal communication with the combustion heater, and is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 preheating section.

60. The system of any one of claims 1-59, further comprising a combustion heating section configured to receive the combustion exhaust after the combustion exhaust passes through the combustion heater.

61. The system of claim 60, wherein the combustion heating section is in thermal communication with the first reformer, and is configured to transfer heat from the combustion exhaust to the first reformer.

62. The system of any one of claims 60-61, wherein the combustion heating section at least partially surrounds the first reformer.

63. The system of claim 58, wherein the NH3 preheating section at least partially surrounds the combustion heater.

64. The system of claim 58, wherein the combustion heater at least partially surrounds the NH3 preheating section.

65. The system of claim 58, wherein the NH3 preheating section comprises an inner section and an outer section.

66. The system of claim 65, wherein the inner section is a cylindrical conduit, and the outer section is an annulus.

67. The system of any one of claims 65-66, wherein the ammonia in the inner section and the ammonia in the outer section are in a counter flow configuration.

68. The system of any one of claims 65-67, wherein the outer section is configured to receive the ammonia stream, and the inner section is configured to output the ammonia stream.

69. The system of any one of claims 65-68, wherein the NH3 preheating section further comprises an NH3 injection section in thermal communication with the combustion heater, wherein the NH3 injection section is configured to transfer heat from the combustion exhaust in the combustion heater to the ammonia in the NH3 injection section.

70. The system of any one of claims 65-69, further comprising a plurality of injection holes along a wall separating the NHs injection section and the outer section, and configured to inject the ammonia into the NH injection section and toward the combustion heater.

71. The system of any one of claim 58-70, wherein the NH3 preheating section comprises a heat exchanging element configured to transfer heat from the combustion exhaust to the ammonia in the preheating section.

72. The system of claim 71, wherein the heat exchanging element comprises a helical feature.

73. The system of any one of claims 71-72, wherein the helical feature winds around the NH3 preheating section.

74. The system of any one of claims 71-73, wherein the helical feature comprises a wire or a vane.

75. The system of any one of claims 71-74, wherein the helical feature has a pitch that varies.

76. The system of any one of claims 71-75, wherein the pitch of the helical feature is progressively smaller along a length of the NH3 preheating section.

77. The system of any one of claims 58-76, wherein the first reformer at least partially surrounds the NH3 preheating section.

78. The system of any one of claims 58-77, wherein the first reformer at least partially surrounds the combustion heater and the NH3 preheating section.

79. The system of any one of claims 1-78, further comprising an output conduit at least partially inside the first reformer configured to receive the first reformate stream.

80. The system of claim 79, wherein the output conduit is configured to transfer the first reformate stream from a first side of the first reformer to a second side of the first reformer opposite to the first side.

81. The system of any one of claims 1-80, further comprising a cooling substance configured to absorb heat from the first reformate stream.

82. The system of claim 81, further comprising a cooling chamber comprising the cooling substance enclosed therein, wherein the cooling chamber separates the cooling substance from an NH3 reforming catalyst in the first reformer.

83. The system of claim 82, further comprising a transfer conduit at least partially inside the first reformer configured to receive the first reformate stream, wherein the transfer conduit is configured to transfer the first reformate stream from the NH3 reforming catalyst to the cooling substance in the cooling chamber.

84. The system of any one of claims 81-83, wherein the cooling substance comprises a ceramic or a metal.

85. The system of any one of claims 81-84, wherein the cooling substance comprises beads or pellets.