MXPA00000458A - Electrochemical hydrogen compressor with electrochemical autothermal reformer - Google Patents

Abstract

A hydrogen production plant includes an electrochemical autothermal reformer (EATR) (200) that provides hydrogen to an electrochemical hydrogen compressor (100). The EATR includes an autothermal reformer region (210), a mixed ion conductor membrane (220) or metal or metal alloy membrane, and an anode supply region (230). An anode gas loop (300) between the anode supply region of the EATR and anode section (110) of the electrochemical hydrogen compressor cell circulates a mixture of hydrogen and a carrier gas therebetween. The carrier gas ensures proper partial pressures of hydrogen in the two regions. A difference in operating temperature between the EATR and the electrochemical hydrogen compressor is exploited by heat exchangers (18, 19, 20 and 22) which efficiently enable certainheating and cooling functions within the combined system.

Description

HYDROGEN ELECTROCHEMICAL COMPRESSOR WITH AUTOTHERMAL ELECTROCHEMICAL REFORMER DESCRIPTION OF THE INVENTION This invention relates to a hydrogen production plant that uses a reformer to deliver hydrogen to a hydrogen compressor, and in particular, to a hydrogen production plant using an autothermal electrochemical reformer (RATE) to provide fuel of hydrogen to an electrochemical hydrogen compressor (CHE). A CHE is essentially a fuel cell operated in reverse. A fuel cell is an electrochemical cell that converts the chemical energy of a fuel directly into electrical energy in a continuous process. The total reaction of the fuel cell typically involves the combination of hydrogen with oxygen to form water. For example, at 25 ° C and 1 atm pressure, the H2 + 02-H20 reaction takes place with free energy change (? G) of -56.69 kcal / moles. In a galvanic cell, this reaction produces a theoretical cell voltage of 1.23 volts. Actual values are typically within the range of 0.9 to 1.1 volts. The main types of fuel cells used now are the proton exchange membrane or solid polymer electrolyte fuel cell, the phosphoric acid fuel cell, the alkaline fuel cell, the solid oxide fuel cell, and the fuel cell. of molten carbonate. Details on these individual technologies can be found in "Fuel Cells, A Handbook, (Revision 3)" published in January 1994 by the Department of the Fossil Energy Office, incorporated herein in its entirety for reference. CHE is an electrochemical cell that converts electrical energy directly to chemical energy in a continuous process. Instead of placing a load between the anode and cathode sections in a fuel cell to produce electricity, in the CHE, an external power supply is placed between the anode and cathode sections to reverse the process. Hydrogen accumulates in the cathode. In this way, a CHE needs two main inputs to function: hydrogen from a source and externally applied voltage. It is an object of the present invention to provide a system that reforms a hydrocarbon fuel to produce hydrogen for use in an electrochemical hydrogen (CHE) compressor. A further object of the present invention is to use an autothermal electrochemical reformer to function as a hydrogen production plant together with an electrochemical hydrogen compressor.

Briefly stated, a hydrogen production plant includes an autothermal electrochemical reformer (RATE) that provides hydrogen to an electrochemical hydrogen compressor. The RATE includes an autothermal reformer region, a mixed ion conductor or a membrane layer, and an anode delivery region. The mixed ion conductor or membrane layer separates the autothermal reformer region from the anode supply region. An anode gas circuit between an anode supply region or side of the RATE and an anode compartment or section of an electrochemical hydrogen compressor cell circulates a mixture of hydrogen or a carrier gas. The carrier gas ensures that the partial pressure of hydrogen in the hydrogen gas circuit remains low relative to the partial pressure of hydrogen in the RAT region of the RATE. A difference in the operating temperature between RATE and CHE is exploited by heat exchangers that efficiently allow certain heating and cooling functions within the system. According to one embodiment of the invention, a hydrogen production plant includes an autothermal electrochemical reformer for use in conjunction with an electrochemical hydrogen compressor, the compressor comprising an anode compartment or section of the compressor and a compartment or section of the compressor cathode., the autothermal electrochemical reformer comprises an autothermal reformer region, a mixed ion conductor or membrane layer, and an anode delivery region. The mixed ion conductor or membrane layer separates the autothermal reformer region from the anode supply region, and a circulation medium is used to circulate a mixture of hydrogen gas and a carrier between the anode supply region of the RATE. and the anode section of the compressor. According to one embodiment of the invention, a hydrogen production plant includes an autothermal electrochemical reformer that provides hydrogen to an electrochemical hydrogen compressor, the autothermal electrochemical reformer comprises a region of autothermal reformer, a mixed ion conductor or a layer of membrane, and an anode supply region. The mixed ion conductor separates the autothermal reformer region from the anode supply region, and a circulation medium is used to circulate a mixture of hydrogen and a carrier gas between the compressor anode section and the anode supply region of the anode. RATE Another feature includes a burner means for burning the excess hydrogen from the exhaust region of the autothermal reformer, a fuel feed means for feeding a hydrocarbon fuel to the region of the autothermal reformer, and a control means, for responding to the medium burner, to control the fuel supply medium. The above objects and others, features and advantages of the present invention will become apparent from the following description which is read together with the accompanying drawings, in which like reference numerals designate the same elements. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates an electrochemical hydrogen compressor, used in accordance with a preferred embodiment of the present invention; and Figure 2 is a schematic diagram of an energy plant according to the present invention. With reference to Figure 1, an electrochemical hydrogen (CHE) compressor 100 includes an anode section 110 and a cathode section 130 separated by an electrolyte 120. Two electrons are separated from the hydrogen molecule in the anode section 110 and they are sent to the cathode section 130 by an external power source 140. The resulting protons produced in an anode section 110 diffuse through the electrolyte 120 which is sufficiently porous, a membrane, and eventually go to the cathode section adjacent 130, such as to recombine with the associated electrons from the external energy source 140, and form the hydrogen molecule. The hydrogen molecule formed can be released from the cathode section 130 at any pressure. Unlike a fuel cell, oxygen is not provided to the cathode section 130 of the CHE. The hydrogen in an anode section 11Q is brought through an electrolyte 120 by the applied external energy source sufficient to solve the pressure and polarization of the hydrogen in the cathode section 130. With reference to Figure 2, a RATE (Electrochemical Autothermal Reformer) 200 includes a RAT (Autothermal Reformer) 210 attached to an anode supply region 230 by a membrane layer 220. The membrane layer 22Q is a mixed ion conductor. . A "reformer" is a known device in which the hydrocarbon fuel is mixed with the vapor, the pressure of a catalyst, to convert the fuel / vapor mixture to hydrogen, carbon monoxide, carbon dioxide, water and impurities. Since most known reformers are sensitive to the presence of impurities, impurities such as sulfur are generally removed from the fuel before entering the reformer. An autothermal electrochemical reformer combines the principles of chemical hydrogen separation and random autothermal reformation. The purpose of the autothermal electrochemical reformer is to effect the selective removal of hydrogen from an autothermal reforming zone of an RATE to bring the reforming reaction to completion while separating the hydrogen component for another use. The operation of RATE 200 together with the composition of membrane layer 220 is the subject of a co-pending application currently filed with it entitled "ELECTROCHEMICAL AUTOTHERMAL REFORMER" (Proxy Registry No. 269-005) and is incorporated herein by reference. reference. The hydrogen produced by RATE 200 is used to feed the CHE as explained further below. Still with reference to Figure 2, RATE 20Q is fed with a hydrocarbon fuel stream from node 1 and in an air stream from node 4. Air is mixed with steam, from a heater * j-60, indicated at node 33 to form the air / vapor mixture. The air / steam mixture is heated in a heat exchanger B2 between node 6 and node 7 before entering RAT 210. RAT 210 operates at temperatures from about 800 ° F (426.7 ° C) to about 2500 ° F ( 1371 ° C), while the anode section CHE 110 operates from about 70 ° F to about 200 ° F (93 ° C) depending on the pressure. A low hydrogen partial pressure in the anode supply region 230 on the side of the RATE 200 is preferable together with a higher partial pressure of hydrogen on the RATE 210 side of RATE 200. In this situation, the hydrogen is transferred via the membrane layer 220 from RAT 210 to the anode supply region 230. That portion of hydrogen that does not pass through the membrane layer 220, leaves the RAT 210 at node 9, along with unreacted fuel or carbon monoxide, and enters to the burner 260 at the node 10 where it burns after it is mixed with air entering the burner 260 at the node 12. The combustion outlet passes through a plurality of AI / A2 heat exchangers, BI / B2, and C1 / C2 before reaching a condenser 280 where the water is removed. The heat is transferred from Al, Bl, and Cl to other parts of the system. The heat is preferably used from the heat exchanger Bl to heat the air / steam mixture (in the heat exchanger B2) described above between the nodes 6 and 7. The heat of the heat exchanger Cl is preferably used in the heater 160 (C2) The use of heat from the heat exchanger Al is described below. An anode gas circuit 300 circulates between the anode section 110 of the CHE 100 and an anode supply region 230 of RATE 200. A mixture of hydrogen gas and a carrier gas leaves the anode section 110 at node 17 with a partial pressure of low hydrogen, since most of the hydrogen has been removed through the electrolyte 120 by the external energy source 140 to the cathode section 130. The carrier gas is preferably any inert gas that does not poison the anode section of CHE 110 or passes through electrolyte 120, or any vapor that does not poison CHE 100. Such carriers include vapqr or inert gases, such as argon or nitrogen. A heat exchanger D1 / D2 transfers heat from a hot side of the anode gas circuit 300 (DI) to a cold side of the anode gas circuit (D2). A heat exchanger CU transfers heat from the hot side of the anode circuit 300 to act as a heat source for use outside the system. The heat exchanger A1 / A2 transfers heat from the burner 260 via the heat exchanger Al to the hot side of A2 in the anode circuit 300. The gas mixture from the anode section of the CHE enters the heat exchanger D1 / D2 on node 16 and it heats up. The gas mixture then enters the heat exchanger A1 / A2 at node 18 where it is further heated before entering the anode supply region 230 of RATE 200 at node 19. The gas mixture is thus preferably heated possibly to be close to the operating temperature of the RATE 200. The presence of the carrier gas allows the partial pressure of hydrogen at the node 19, and therefore in the supply region of the anode 230, to be low compared to the partial pressure of hydrogen in RAT 210, which is necessary for the hydrogen from the RAT 210 to cross the membrane layer 220 in the anode supply region 230 by virtue of a hydrogen concentration or partial pressure gradient. The hydrogen produced by the RATE 200 joins the gas mixture returning from the CHE 100 before entering the heat exchanger D1 / D2 at the node 20 where the heat is heated from the mixture. More heat is removed from the mixture by the heat exchanger CU such that the mixture entering the anode section 110 at the node 22 cools near the operating temperature of the CHE 100. The hydrogen produced by RATE 200 is transported in this way via the gas circuit of the anode 300 to the CHE 100. The hydrogen in the section of the anode 110 is separated from its electrons by the external energy source 140. The resulting protons pass through the electrolyte 120 on its way to the cathode section 130 where they combine with the associated electrons of the external energy source 140 to form molecular hydrogen. This hydrogen formed in the cathode section 130 can be released from the cathode section 130 at any pressure in the manner previously described, with reference to Figure 1. A refrigerant, which can be air or liquid, enters the cooler 150 via the nodes 26 and 27 for cooling the CHE 100. The refrigerant leaves the cooler 150 via the node 28, traveling to the condenser 280, where the refrigerant is used to provide cooling capacity for the condenser 280, since the refrigerant is cold with regard to to the flue gases of the burner 260. If the refrigerant is air, it exits via the node 29. If the refrigerant is liquid, a closed circuit (not shown) is preferably installed in such a way that the refrigerant can be reused. Water removed from burner outlet 260 is pumped from condenser 280 to node 31 by pump 270 to heater 160 at node 32. Pump 270 is preferably a conventional circulation pump unless the RAT 210 is run at high Pressure. The RATE 200 functions properly as long as there is a sufficient partial pressure gradient of hydrogen between the RAT 200 and the anode supply region 230. As described above, this pressure gradient is maintained by the action of the anode gas circuit 300. In an alternate arrangement, the RAT 210 is run at high pressure. High pressure considerations include using a positive displacement pump in place of the conventional circulation pump 270, compressing the combustible air between nodes 4 and 5, and optionally adding a pressure reduction step between nodes 9 and 10. In a suitable large system, a gas turbine between the nodes 9 and 10 can provide the required pressure-reducing cap function, with the mechanical energy produced by the turbine used to energize an air compressor (not shown) between the nodes 4 and 5. The presence of the carrier gas allows the anode circuit 300 to operate at a partial pressure gradient of hydrogen between the anode supply region 230 of the RATE 200, where the hydrogen is supplied, for the anode section 110 of the CHE. , where the hydrogen is consumed, while maintaining the high total pressure in the gas circuit of the anode 300. The anode section of the CHE 110 is not fully sensitive to the partial pressure of hydrogen while contaminants are not present, such as carbon monoxide. It is preferable to use steam or steam as the carrier since the presence of water in the anode gas circuit 300 is advantageous if the water is condensed on the cold side of the anode circuit 300 (DI and CU) and evaporated in the hot side of the anode gas circuit 300 (D2 and A2). In this form, the partial pressure of the hydrogen at the node 19 entering the anode supply region RATE 230 can be much smaller than the hydrogen partial pressure at the anode section of the CHE 110. As described above, having a higher partial pressure in RAT 210 than in the anode supply region 230 allows hydrogen to cross membrane layer 220 from RAT 210 to the anode supply region 230.

When the partial pressure of hydrogen is greater in the anode supply region 230 than in the RAT 210, the hydrogen crosses the membrane layer 220 in reverse; that is, in a direction from the supply region of the anode 230 to RAT 210. Monitoring the temperature of the outlet from the burner 260 to the node 14 exploits this fact. Decreasing the amount of the hydrogen released from the cathode section 130 causes an instantaneous increase in the partial pressure of hydrogen in the gas circuit of the anode 300. A sufficient increase in the partial pressure of the hydrogen in the anode supply region 230 causes the hydrogen moves through RATE 200 in reverse, moving from the anode supply region 230 to RAT 210, until the hydrogen partial pressures between the membrane layer 220 are equal. When the partial pressures of hydrogen between the membrane 220 are equal, there is no hydrogen concentration and the hydrogen transport between the membrane layer 220 ceases. The reformed hydrogen thus leaves RAT 210 via the node 9 and enters the burner 260, thus causing the temperature to increase at node 14. This increase in temperature indicates a need to decrease the supply of fuel at node 1. Conversely, increasing the amount of hydrogen released from the cathode section of CHE 130 causes the temperature of the burner to decrease, as monitored by node 14 and therefore indicates the need to increase the fuel supply. It is considered that the setting of the monitor and feedback loop to increase or decrease the power supply is within the ability of one skilled in the art, therefore no additional details are required. Having described the preferred embodiments of the invention with reference to the accompanying drawings, it is understood that the invention is not limited to those precise embodiments, and that changes and modifications may be made thereto by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.

Claims (10)

1. CLAIMS 1. A hydrogen production plant, characterized in that it comprises: an electrochemical autothermal reformer for use together with an electrochemical hydrogen compressor; the electrochemical hydrogen compressor includes an anode section of the compressor and a cathode section of the compressor; the electrochemical autothermal reformer includes an autothermal reformer region, a mixed ion conductor, and an anode supply region, the mixed ion conductor separates the autothermal reformer region from the anode supply region; and a circulating means for circulating a mixture of hydrogen and carrier gas between the anode section of the compressor and the anode reformer supply region.
2. 2. A hydrogen production plant according to claim 1, characterized in that the electrochemical hydrogen compressor is an electrochemical hydrogen compressor of the proton exchange membrane type, an electrochemical hydrogen compressor of the phosphoric acid type, a compressor of electrochemical hydrogen of the phosphoric acid type, an electrochemical hydrogen compressor of the alkaline type, an electrochemical hydrogen compressor of the solid oxide type, and an electrochemical hydrogen compressor of the molten carbonate type.
3. 3. A hydrogen production plant according to claim 1, characterized in that it further comprises: a burner means for exhausting and burning excess hydrogen from the autothermal reformer region; and a fuel supply means, which responds to the burner means, to feed the hydrocarbon fuel to the region of the autothermal reformer.
4. 4. A hydrogen production plant according to claim 3, characterized in that it further comprises: an air supply means for feeding a mixture of air and steam to the region of the autothermal reformer; a steam production means, connected to the air supply means, to produce steam; and a first heat exchanger between the outlet of the burner means and the steam production means.
5. 5. A hydrogen production plant according to claim 4, characterized in that it further comprises: a means for increasing the temperature to increase the temperature of the mixture of hydrogen and carrier gas as soon as the mixture of hydrogen and carrier gas flows in a first path from the anode section of the compressor to the anode supplying region of the reformer; and a means for lowering the temperature to lower the temperature of the mixture of hydrogen and carrier gas as soon as the hydrogen and carrier gas mixture flows in a second path from the anode supplying region of the reformer to the compressor anode section.
6. 6. A hydrogen production plant according to claim 5, characterized in that the means for increasing the temperature and the temperature decreasing means together form a second heat exchanger.
7. 7. A hydrogen production plant according to claim 6, characterized in that it further comprises a third heat exchanger between an outlet of the burner medium and the mixture of hydrogen and carrier gas in the first path.
8. 8. A hydrogen production plant according to claim 7, characterized in that it also comprises a fourth heat exchanger between the outlet of the burner medium and the mixture of hydrogen and gas carrying air and steam in the air supply means.
9. 9. A hydrogen production plant according to claim 8, characterized in that it also comprises a fifth heat exchanger between the mixture of hydrogen and the carrier gas in the second path and a point outside the production plant.
10. 10. A hydrogen production plant, characterized in that it comprises: an electrochemical autothermal reformer for use together with an electrochemical hydrogen compressor; the compressor includes an anode section of the compressor and a section of the cathode of the compressor; the electrochemical autothermal reformer that includes a region of autothermal reformer, a mixed ion conductor, and an anode supply region, co? the mixed ion conductor that separates the autothermal reformer region from the anode supply region; and a circulating means for circulating a mixture of hydrogen and a carrier gas between the compressor anode section and the anode supplying region of the reformer; a burner means to exhaust and burn excess hydrogen from the region of the autothermal reformer; a fuel feed means for feeding the hydrocarbon fuel to the autothermal reformer region; and a control means, which responds to the burner means, to control the fuel feed means.