Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0242—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical
  • B01J8/0257—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical in a cylindrical annular shaped bed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0285—Heating or cooling the reactor
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
  • C01B3/047—Decomposition of ammonia
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0662—Treatment of gaseous reactants or gaseous residues, e.g. cleaning
  • H01M8/0687—Reactant purification by the use of membranes or filters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/00106—Controlling the temperature by indirect heat exchange
  • B01J2208/00115—Controlling the temperature by indirect heat exchange with heat exchange elements inside the bed of solid particles
  • B01J2208/00123—Fingers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/00504—Controlling the temperature by means of a burner
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/0053—Controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M2008/1095—Fuel cells with polymeric electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04201—Reactant storage and supply, e.g. means for feeding, pipes
  • H01M8/04216—Reactant storage and supply, e.g. means for feeding, pipes characterised by the choice for a specific material, e.g. carbon, hydride, absorbent
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
  • H01M8/0612—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material
  • H01M8/0625—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material in a modular combined reactor/fuel cell structure
  • H01M8/0631—Reactor construction specially adapted for combination reactor/fuel cell
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/08—Fuel cells with aqueous electrolytes
  • H01M8/083—Alkaline fuel cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/22—Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
  • H01M8/222—Fuel cells in which the fuel is based on compounds containing nitrogen, e.g. hydrazine, ammonia
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/10—Process efficiency
  • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Definitions

• the invention relates to the energy efficient generation of hydrogen by cracking ammonia stored in a solid storage material, e.g. as metal ammine salts, and the generation of power using a low temperature fuel cell.
• Ammonia is a widely used chemical with many applications. One specific application is as fuel for fuel cells.
• Ammonia can be a zero-carbon fuel if the CO2 produced during the conventional production process is sequestered or if it can be synthesized using nuclear energy or renewable energy, e.g. wind (see e.g. United States Patent No. US 2008/0248353; and Chakraborty et al., Fuel Cells Bulletin, October 2009, both incorporated herein by reference in their entirety.)
• ammonia needs to be cracked into hydrogen and nitrogen by passing it through a reactor.
• Ammonia cracking is an endothermic process requiring 46 kJ/mol of ammonia according to the following reaction:
• a storage method involving ad- or absorption in a solid can circumvent the safety hazard of anhydrous liquid ammonia. It is desirable to operate an ammonia cracker for production of hydrogen as energy efficient as possible.
• an ammonia-based hydrogen generation reactor 110 comprising:
• the hydrogen generation reactor 10 may also comprise heat transfer fins 10 extending from the surface of the combustion chamber 2 into the cracking chamber 1 , and flow distribution holes 5 enabling uniform feeding of ammonia to the cracking chamber 1 by flow through the flow distribution holes 5.
• the invention in a second aspect, relates to system for generating hydrogen comprising at least one storage unit 119, 120, 400 containing a solid ammonia storage material 7 capable of releasing ammonia by desorption, preferably a metal ammine salt, which, when in operation, is combined with at least one hydrogen generation reactor 110 of claim 1 , wherein, when in operation, the waste heat of the at least one hydrogen generation reactor 110 is transferred to at least one storage unit 119, 120, 400 being in operation.
• a solid ammonia storage material 7 capable of releasing ammonia by desorption, preferably a metal ammine salt
• a first preferred embodiment of the second aspect is a system wherein the at least one storage unit 119, 120 has a hollow concentric channel 8 extending partly or all the way through the unit in which, when in operation, one of said at least one hydrogen generating reactor 110 is inserted.
• the solid ammonia storage material 7 in the storage unit 119, 102 may be used as a part of a thermal insulation between the hydrogen generation reactor 110 operated at a temperature higher than 300°C and the surroundings.
• the storage unit 120 may have an annular chamber 9 at the outer side with an inlet and outlet for fluid functioning as a heat exchanger for providing heat to desorb ammonia.
• the storage unit 119, 120 may have a space 11 between the hydrogen generating reactor 110 and an inner wall of the storage unit 119, 120, when said hydrogen generating reactor 110 is inserted.
• the hydrogen generation reactor 110 may be operated at a temperature higher than 300°C, in which case the space 11 can be varied or the space 11 is filled with a fluid which can be changed, so as to control the heat transfer between the hydrogen generating reactor 110 and the storage unit 119, 120.
• any of the above embodiments of the system of the second aspect of the invention may further comprise a start-up unit 170 to assist the heating up of the combustion chamber 2 of the hydrogen generation reactor 110, and a heat exchanger 160 to recover heat of vaporization of steam formed in the combustion chamber 2 and to mix the ammonia from the storage unit 119,120 and air for entry into the
• combustion chamber 2 may comprise two modules each comprising one of said a least one storage unit 119, 120 having a hollow concentric channel 8 extending partly or all the way through the unit in which, when in operation, one of said at least one hydrogen generating reactor 110 is inserted.
• the system comprises at least two storage units 400 and one well isolated hydrogen generation reactor 110 as a stand-alone unit from which the heat generated in the combustion chamber 2 can be provided to the at least two storage units 400 externally or can be provided to a heat exchanger zone that extends into the storage units 400 via valves which direct the combustions products sequentially to one of the at least two storage units 400 which is in operation.
• the heat of the combustion products may be delivered to the storage unit 400 via a heat exchanger 160 exchanging heat from the combustion products from the combustion chamber 2 and/or the crack products from cracking chamber 1 to a circulating liquid which delivers a part of the heat to at least one of the at least two storage units 400.
• a third aspect of the invention is a power generation device 60, 70 comprising an alkaline fuel cell 151 or a PEM fuel cell 152 provided with an absorber 153 for absorbing traces of ammonia and the system for generating hydrogen of the first preferred embodiment of the second aspect, in which system the solid ammonia storage material 7 in the storage unit 119, 102 is used as a part of a thermal insulation between the hydrogen generation reactor 110 operated at a temperature higher than 300°C and the surroundings, wherein hydrogen from said system is fed to the alkaline fuel cell 151 or to the absorber 153, and after the absorption of traces of ammonia in the absorber 153 to the PEM fuel cell 152.
• the power generation device of the third aspect of the invention may further comprise a pump 180 which enhances the flow of ammonia from the storage unit 119, 120 to the hydrogen generating reactor 110 when the desorption pressure from the solid storage material 7 in the storage unit 2 is lower than the pressure level required to overcome the pressure drop during flow of ammonia through the power generation device 60, 70.
• a further aspect of the invention is a power generating device 60, 70 comprising an alkaline fuel cell 151 or a PEM fuel cell 152 provided with at least one absorber 153 for absorbing traces of ammonia, the system for generating hydrogen of the second preferred embodiment of the second aspect of the invention from which hydrogen is fed to the alkaline fuel cell 151 or to the absorber 153 and, after the absorption of traces of ammonia in the at least one absorber 153, to the PEM fuel cell 152, and a pump 180 which enhances the flow of ammonia from the storage unit 400 to the hydrogen generating reactor 110 when the desorption pressure from the solid storage material 7 in the storage unit 2 is lower than the pressure level required to overcome the pressure drop during flow of ammonia through the power generation device 60, 70.
• the invention relates to a method for operating a system for generating hydrogen comprising at ieast one storage unit 119, 120, 400 containing a solid ammonia storage material 7 capable of releasing ammonia by desorption, preferably a metal ammine salt, wherein waste heat from the hydrogen generation reactor (110) is recovered and used to fully or partially deliver the heat of desorption of ammonia from the ammonia storage material 7 to the storage unit 2.
• the method may further include introducing fuel cell coolant fluid of a fuel cell to an outer jacket of the storage unit 2 through a tube and returning the coolant fluid after exchanging heat with the ammonia storage material 7.
• Fig. 1 shows a schematic graph of an embodiment of a hydrogen generation reactor with inlets and outlets to the reactor in an embodiment to the present invention.
• Fig. 2 shows a schematic cross sectional view of an embodiment of hydrogen generation reactor. The arrows show possible flow directions in different chambers.
• Fig. 3 shows a schematic graph of a storage unit which could be used together with the hydrogen generation reactor of Fig. 1 or Fig. 2 in a system for generating hydrogen according to the invention.
• Fig. 4 shows a schematic graph of an embodiment of a storage unit with outer annulus which could be used together with the hydrogen generation reactor of Fig. 1 or Fig. 2 in a system for generating hydrogen according to the invention.
• Fig. 5 shows a perspective view illustrating an embodiment of the hydrogen generation reactor-storage unit system.
• the hydrogen generation reactor acts also as a heating means and the storage unit also provides means for insulating the hydrogen generation reactor.
• Fig. 6 shows a process flow diagram for an embodiment of a system comprising a storage unit and a hydrogen generation reactor.
• Fig. 7 shows a process flow diagram for an embodiment of a system comprising a storage unit and a hydrogen generation reactor for power generation by an alkaline fuel cell.
• Fig. 8 shows a process flow diagram for an embodiment of a system comprising a storage unit, a hydrogen generation reactor and an absorber purifying the cracked product from trace ammonia for power generation by a PEM fuel cell.
• Fig. 9 shows a process flow diagram for an embodiment of a system comprising a storage unit, a hydrogen generation reactor cracking ammonia and two absorbers for continuous purification of the cracked product from trace ammonia for power generation by a PEM fuel cell.
• Fig. 10 shows a process flow diagram for a system comprising two sets of an embodiment of a storage unit-hydrogen generation reactor system, and two absorbers for continuous power generation by a PE fuel cell.
• Fig. 11 shows a process flow diagram schematically showing direct transfer of heat from the hydrogen generation reactor exhaust gas to the ammonia storage unit(s).
• Fig. 12 shows a process flow diagram schematically showing transfer of heat from the hydrogen generation reactor exhaust gases to the ammonia storage unit(s) via a heat carrying fluid.
• the heat from the hydrogen generation reactor exhaust gases is first transferred to a heat carrying liquid which in turn transfers the heat to the storage unit(s).
• the present invention aims at an ammonia cracker which may be interfaced with a unit containing solid-state ammonia storage material in a user-friendly way, and an improvement of the energy efficiency of the system by utilizing waste heat from the cracker and waste heat from the fuel cell as heat sources to release ammonia from the storage material.
• ammonia cracking is an endothermic process requiring 46 kJ/mol of ammonia according to the following reaction:
• Fuel cells may also generate more than 40% of waste heat.
• this heat is generated at rather low temperature (e.g. 80 °C), which is considered as low-quality heat. Therefore, with low temperature proton exchange membrane fuel cells (PEMFCs) this heat is generally dissipated in the ambient. This dissipation process itself represents a big loss of system efficiency, on top of which the dissipation process consumes power for operating fans or blowers.
• PEMFCs proton exchange membrane fuel cells
• Metal ammine salts are ammonia absorbing and desorbing materials, which can be used as solid storage media for ammonia.
• Preferred metal ammine salts used in the present invention have the general formula M a (NH3) n X 2 , wherein M is one or more cations selected from alkali metals such as Li, Na, K or Cs, alkaline earth metals such as Mg, Ca, Sr or Ba, and/or transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, or Zn or combinations thereof, such as NaAI, KAI, K 2 Zn, CsCu, or K 2 Fe;
• X is one or more anions selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate, and phosphate ions;
• a is the number of cations per salt molecule;
• z is the number of anions per salt molecule;
• n is the coordination
• metal ammine salts which can be used in the present invention are more fully described in WO 2006/012903 A2 and WO 2006/081824, both incorporated herein by reference in their entirety.
• the solid metal ammines are described as an ideal "hydrogen carrier" fuel for vehicular and stationary power systems because of its high hydrogen content and incorporated safety issues.
• metal ammine salts are the preferred solid ammonia storage materials in the present invention.
• Degassing of ammonia from solid ammonia storage materials is a process that requires heat, see WO 1999/01205 A1 , US 5,161 ,389 and WO 2006/0 2903 A2, all incorporated herein by reference in their entirety.
• heat can be delivered by external heating of the storage container (WO 1999/01205 A1) or placing the heating element inside (US 5,161 ,389 and WO 2006/012903 A2).
• metal ammine salts e.g. Sr(NH3)eCl2 or
• the invention relates to an energy efficient cracking of ammonia for hydrogen production from ammonia stored as solid ammonia storage material, preferably as metal ammine salts, and integration of the system with low temperature fuel cells, e.g. PEM (polymer electrolyte membrane) or fuel cells of the alkaline type, for high efficiency power generation.
• low temperature fuel cells e.g. PEM (polymer electrolyte membrane) or fuel cells of the alkaline type
• the invention relates to an ammonia-based hydrogen generation reactor (hereinafter also referred to as "ammonia cracker” or “jacket-cracker” or simply “cracker”) comprising of combustion chamber for ammonia and/or off-gas from the fuel cell anode, a cracking chamber, an ammonia preheating chamber, and a combustion gas heat recovery chamber. All the four chambers of the cracker are concentric with the combustion chamber in the middle. The cracking chamber surrounds the combustion chamber.
• the cracker may also comprise a plurality of axially connected metal sheets for better dissipation of heat from the combustor to the cracking conduit.
• Ammonia enters at one end of the preheating chamber and after having traveled through the length of the preheating chamber, enters the cracking chamber, usually through a multiple of entrance holes in an end cap of the cracking chamber.
• the combustion chamber may be extended through the end cap of the cracking chamber to lead the combustion exhaust through the jacket.
• the cracking chamber contains an ammonia cracking catalyst and the combustion chamber contains a combustion catalyst capable of combusting NH 3 or H2.
• the invention in another aspect relates to a system for generating hydrogen comprising at least one storage unit 119, 120, 400 containing a solid ammonia storage material 7 capable of releasing ammonia by desorption, preferably a metal ammine salt, which, when in operation, is combined with a hydrogen generation reactor 110 of the fist aspect, wherein, when in operation, the thermal energy of the heat recovered from the combustion products, of the hydrogen of the
• combustion chamber 2 of the hydrogen generation reactor 1 0 is transferred to at least one storage unit 119, 120, 400 being in operation.
• the system for generating hydrogen may, in a preferred embodiment, includes a storage unit (cartridge) containing, e.g. metal ammine salts, into which the jacket- cracker may be plugged, and into which or with which the jacket-cracker is plugged or interfaced, when the system is in operation.
• a storage unit e.g. metal ammine salts
• the hollow concentric channel in the middle of the cartridge may extend all the way through the cartridge or may only extend into the cartridge from one end or side and not penetrate all the way through.
• the cartridge may contain a hollow chamber e.g. in the form of a jacket covering fully or partly the outer surface of the cartridge for waste heat recovery from the fuel cell coolant fluid. Fluid interfaces of ammonia and coolant fluid from the fuel cell can be established as mentioned below.
• Ammonia released from the storage unit may be provided to the cracker through a tube joining the cracker and the storage unit via e.g. a quick connect or similar interface for easy replacement of the storage unit.
• the invention also relates to a method for recovering the waste heat from the jacket-cracker and using the heat to fully or partially deliver the heat of desorption for ammonia.
• the salts used to store ammonia have very low thermal conductivities (in the order of 10 "2 W/mK comparable to microporous high temperature insulation from
• the device for performing the method includes a cylindrically or similar three-dimensional shaped block of metal ammine salts in a container having a hollow concentric channel extending all the way through the container. The diameter of the hollow channel is at least wide enough to receive the cracker.
• the method may also comprise introducing ammonia released from the storage unit to the cracker through a tube joining the cracker and the storage unit via a quick connect coupling or similar interface for easy replacement of the storage unit.
• the invention also relates to a method for recovering the heat loss from the jacket-cracker and using the heat to fully or partially deliver the heat of desorption for ammonia from the ammonia storage material via an annular space surrounding the outer surface of the storage container for waste heat recovery from the fuel cell coolant.
• the method may also include introducing the fuel cell coolant fluid to an outer jacket of the storage unit through a tube which may be connected to the outer jacket via a quick connect and to return the coolant fluid after exchanging heat with the storage material e.g. through a tube.
• Fig. 1 is a schematic of the jacket-cracker 110. Ammonia and/or hydrogen (not shown in Fig. 1) is mixed with air and the mixed gas enters the combustion chamber 2 which is connected to a combustion exhaust, as shown in Fig. 1 .
• Hydrogen could come from a fuel cell anode exhaust.
• Ammonia for cracking enters the reactor 110 through the preheating chamber 3.
• Fig. 2 indicates ammonia flow distribution holes 5 through which preheated ammonia enters into the cracking chamber 1. Also shown are heat transfer fins 10 attached to the outer wall of the combustion chamber 2 and extending into the cracking chamber 1 for better heat distribution for the endothermic cracking of ammonia.
• the exhaust gas of the combustion chamber 2 passes through the outermost annulus 6 before leaving the jacket-cracker 1 0 through one or more outlets.
• the cracking chamber exhaust gas which is a mixture of H 2 , N 2 and NH 3 of different concentrations depending on the operating point of the jacket-cracker, leaves the cracking chamber 1 through one or more outlets. All the inlets and outlets of the jacket-cracker are situated at the same end of the jacket-cracker ensuring countercurrent gas flow in each chamber.
• the combustion chamber can contain any ammonia combustion or oxidation catalyst e.g. 0.5% Pt on 3 mm alumina pellets from Johnson Matthey.
• the cracking chamber can contain any ammonia cracking catalyst e.g. commercially available 2% Ru on 3 mm alumina pellets from Johnson Matthey.
• the storage unit 119 includes a cylinder with a hollow concentric channel 8 all the way through the unit.
• the diameter of 8 is large enough to insert the jacket-cracker 110.
• the ammonia containing metal ammine salt in space 7 surrounds the channel 8.
• a similar container 120 is shown in Fig. 4, with the difference that this container has an annular space 9 surrounding the main storage chamber containing the meal ammine salt 7.
• Fig. 5 shows how the cracker can be interfaced with the storage unit 119 or 120.
• the space or gap 11 between the cracker 110 and the inner wall of the of the storage unit 119, 120 can be adjusted to control the heat transfer from the cracker to the storage unit and in turn control or influence the ammonia desorption rate.
• An insulating or a conducting material can also be used to fill up the space in order to decrease or increase the heat transfer from the cracker to the storage unit, respectively.
• An exemplary solid-ammonia based mobile hydrogen generation apparatus 50 shown in Fig. 6 includes an ammonia storage unit 120, a cracker 110, a heat exchanger 160, a start-up unit 170, a vacuum pump 180, and a battery (not shown).
• the cracker 110 is plugged into the storage unit 120.
• the startup unit 170 is needed only during the first few minutes to get the combustion chamber 2 ready for combustion of ammonia. To our knowledge, no catalyst exists to combust ammonia at room temperature, so the catalyst bed in the combustion chamber 2 of cracker 110 needs to be heated up for ammonia combustion.
• the start-up unit 170 comprises a heating rod inserted into a catalyst bed filled with ammonia cracking catalyst.
• this unit produces a mixture of H2, N2, and ammonia which is transported through tube 260 and mixed with air introduced through tube 220.
• An air pump (not shown) can be used to deliver air.
• vacuum pump 180 pulls ammonia from the storage unit 120 when the temperature has not reached a level where a suitable desorption pressure above atmospheric level has been reached.
• the mixture is then forced to the combustion chamber 2 of the cracker 110 through heat exchanger 160 where it is preheated by exchanging heat with the combustor exhaust gas flowing to the heat exchanger 160 through tube 230.
• the heat exchanger 60 is used mainly to transfer the heat of vaporization of the steam (water vapor) exiting he combusting chamber 2 to the inlet fuel/air mixture.
• the channels of heat exchanger 160 are also used as mixing chambers for air and combustion fuel.
• the combustion exhaust gas leaves the heat exchanger 160 through tube 297.
• the ammonia flow from storage unit 120 is switched through tube 210 to mix with air and then taken through the heat exchanger 160 to the combustion chamber 2.
• the cracking chamber 1 in cracker 110 which is in thermal contact with the combustion chamber 2 , is heated up to the temperature required for cracking. Depending on the required purity of the l- (in terms of slip ammonia concentration), the temperature can be selected, but typically this temperature will be between 300°C to 700"C.
• the ammonia for cracking enters the cracking chamber 1 through tube 200.
• a power generator 60 with an alkaline type fuel cell 151 is used.
• the apparatus 60 shown in Fig. 7 uses the same hydrogen generation system 50 shown in Fig. 6.
• the fuel cell stack coolant fluid is passed via tube 270 through the outer chamber 9 of the storage unit 120 for exchanging heat to the storage material 7.
• the outlet from the storage unit 2 can be passed through a radiator via tube 280, if more heat removal is needed by the coolant or directly to the fuel cell by-passing the radiator via tube 290.
• the fuel cell anode exhaust gas which contains unconverted H2 can be transported to the combustion chamber 2 of the cracker 110 via tube 300 to combust the hydrogen in the stream.
• FIG. 8 Another embodiment of the invention is a power generator 70 with a proton exchange membrane (PE ) type fuel cell 152 which will be explained now.
• the apparatus 70 is shown in Fig. 8 and is similar to the one described in Fig. 7, with the exception that the exhaust gas from cracker 110 in line 240 is passed through a trace ammonia absorber 153 before being fed it to the anode side of the PEM fuel cell 152.
• the absorber 153 could be a cylindrical tube filled with absorbing material.
• Activated carbon treated with acid e.g.
• H 2 S0 4 acts as a good absorbing material for ammonia.
• Some metal ion exchanged Y-zeolite can also be used as the absorbing material.
• the absorber could be regenerated on site by heating it up under air flow or could be replaced together with the storage unit 120. It is also possible to use at least two absorbers 153 in parallel to avoid stopping the operation of the power generator 70 when the absorber material is saturated, as shown Fig.9.
• the purpose of using more than one absorber 153 is to make the absorption process operating continuously, at least one absorber 153 will be in operation mode while the other one will be in the regeneration mode.
• the absorber 153 contains a Cu-ion exchanged Y-zeolite as an absorbent, complete on-site regeneration is possible by heating the bed to 200°C while flowing air through the bed. This heat can be provided form one of the hot sources of energy in the system, e.g. combustion product gas.
• FIG. 10 Yet another embodiment of the inventions is a continuous hydrogen generator, which will be will be explained now.
• This embodiment shown in Fig. 10 comprises two storage units 120 with embedded cracker units 1 (shown as UNIT 1 and UNIT 2), two heat exchangers 160, and a startup unit (SU) 170.
• ammonia can be pumped from the storage container 119, 120 of unit 1 to the thermal startup unit.
• the product gas from the start-up unit 170 (typically being 35% H 2 andl 1 % N 2 and rest NH 3 ) is mixed with air and passed through the heat exchanger 160 to the combustion chamber 2 of UNIT 1.
• the exhaust gas from the combustion chamber 2 exchanges heat with the inlet gas to the combustion chamber 2 in the heat exchanger 160.
• each storage unit module 2 in UNIT 1 and UNIT 2 has a cracker 110 inserted during operation.
• the jacket-cracker 110 is a stand-alone unit that is very well insulated, e.g. by vacuum-type insulation with radiation shield, and the heat of the exhaust gas provides the thermal energy to be transported to the ammonia storage unit or cartridge 400 that is in operation. This heat transfer can be accomplished by a heat exchanger zone that extends into the storage unit in a similar way as if the cracker 110 was inserted.
• the hot product gas from the jacket-cracker 110 can be provided to the storage unit(s) 400 externally, similarly to what has been mentioned about the integration of an external heat exchanger for the fuel cell coolant fluid.
• One such embodiment is also shown in Fig. 11.
• combustion chamber feed is passed on to provide heat of desorption to the ammonia storage cartridges 400.
• the combustion gas needs to transfer heat all along the length of the cracking chamber 1 at a very high temperature, for example not below 300 °C, but possibly much higher, more heat is generated in the combustion chamber 2 than is consumed by the ammonia cracking reaction in the cracking chamber 1. This ensures that there is a great amount of recoverable heat available in the
• combustion exhaust gas has to be above 50 °C for effective heat exchange with the storage cartridge 400 for ammonia desorption. This can be ensured by methods including, but not limited to, varying the feed to the combustion chamber 2, changing the combustion to cracking ratio, and changing the size of the heat exchanger 160 used for transferring heat from the combustion exhaust gas to the combustion feed. In such an embodiment, only one cracker 110 has to be implemented in the system, even if several storage units 400 are a part of the complete hydrogen or power generating system 60, 70.
• product gases from the jacket-cracker 110 exchange heat to a heat carrier fluid which carries the heat to the storage unit 400 for ammonia desorption.
• a heat carrier fluid which carries the heat to the storage unit 400 for ammonia desorption.
• One such embodiment is shown in Fig. 12.
• Either one or both of the exhaust gases of cracker 110 transfer heat to a circulating fluid, e.g. silicone oil, which in turn transfers a part of the heat to one or more ammonia storage units 400.
• the heat carrying fluid can first exchange heat with the combustion chamber exhaust gas and then with the cracker chamber exhaust gas. After exchanging heat with the combustion chamber exhaust a part or all of the flow can go on to exchange heat from the cracking chamber exhaust gas.
• the heat recovery from the jacket-cracker exhaust gas can also take place in the reverse order, i.e. first from the cracking chamber exhaust gas and then from the combustion chamber exhaust gas.
• the system can be integrated with fuel cell stacks as mentioned in the above paragraph for power generation operation.

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• 2011
  • 2011-03-02 WO PCT/EP2011/001046 patent/WO2011107279A1/en active Application Filing
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