Integrated reversible fuel cell system based on dual-function water circulation and electric pile thereof
The invention relates to a divisional application of an invention patent with the application date of 2016, 12 and 30 and the application number of 201611257931.5, and the invention is named as an integrated reversible fuel cell system.
Technical Field
The invention relates to a fuel cell system, in particular to an integrated reversible fuel cell system based on dual-function water circulation and a galvanic pile thereof.
Background
The hydrogen energy storage technology is considered as an important support for the large-scale development of the smart grid and the renewable energy power generation, and is increasingly the focus of energy technological innovation and industrial support of multiple countries.
A fuel cell is a device that directly converts chemical energy of hydrogen and oxygen into electrical energy through an electrode reaction, and is generally composed of a plurality of unit cells, each of which includes two electrodes (an anode and a cathode) separated by an electrolyte member and assembled in series with each other to form a fuel cell stack. By supplying each electrode with the appropriate reactants, i.e. supplying one electrode with fuel and the other with oxidant, an electrochemical reaction is achieved, resulting in a potential difference between the electrical machines and thus the generation of electrical energy.
The Reversible Fuel Cell (RFC) is a chargeable and dischargeable energy storage cell which combines the water electrolysis hydrogen production technology and the hydrogen-oxygen fuel cell power generation technology, namely 2H2O + electric → 2H2+O2The forward and reverse processes are circularly carried out. The active substances of pure hydrogen and pure oxygen of the hydrogen-oxygen fuel cell power generation system can be regenerated through a water electrolysis hydrogen production technology, so that the energy storage effect is achieved. Compared with the secondary battery currently applied, the reversible fuel cell has higher specific energy and specific power, can particularly realize higher energy storage capacity, has no self-discharge in use, is not limited by the discharge depth and the battery capacity, and the like, and is a novel high-capacity electric energy storage cell with wide development prospect.
The reversible fuel cell can realize the dual-mode work of a fuel cell mode and an electrolysis mode, and integrates a water electrolysis hydrogen production system and a fuel cell power generation system into a reversible fuel cell system, thereby simplifying the system structure of the energy storage device and improving the reliability of the system and the specific energy of the system. The reversible fuel cells can be classified into alkaline oxyhydrogen reversible fuel cells, proton exchange membrane oxyhydrogen reversible fuel cells, and solid oxide oxyhydrogen reversible fuel cells according to electrolyte characteristics.
Chinese patent CN 102427144a discloses a regenerative fuel cell device and system, which comprises a first insulating plate, an oxygen electrode collector plate, an oxygen electrode flow field plate, a membrane electrode, a hydrogen electrode collector plate, a hydrogen storage material chamber, and a second insulating plate, which are tightly stacked in sequence; the regenerative fuel cell also comprises an air inlet pipe and an air outlet pipe, one end of the air inlet pipe and one end of the air outlet pipe are communicated with the gas circulation channel of the oxygen electrode flow field plate, and the other end of the air inlet pipe and the other end of the air outlet pipe are communicated with the outside air; the regenerative fuel cell device further includes a fan that is disposed to face an end of the air intake duct that communicates with outside air. The patent has the defects that firstly, oxygen needs to be obtained from air during power generation, an integral structure without interaction with the outside cannot be formed, oxygen generated during electrolysis is directly discharged to the atmosphere, and moisture in the oxygen is discharged to the atmosphere along with the oxygen; secondly, air blown into the regenerative fuel cell main body and generated water are discharged from an air discharge pipe at the lower part of the oxygen electrode flow field plate during power generation, so that water recycling cannot be realized; therefore, the fuel cell cannot operate in an air-tight environment, and particularly cannot be applied to an oxygen-free environment. The prior art lacks a complete, closed, integrated fuel cell system, and an integrated reversible fuel cell system that can be applied in underwater environments without an air environment, such as submarines, space environments, such as space stations, and low air mountain environments, mine tunnel environments, and even in heavily polluted or toxic environmental areas.
Disclosure of Invention
It is an object of the present invention to overcome the above-mentioned deficiencies of the prior art by providing an integrated reversible fuel cell system.
The purpose of the invention can be realized by the following technical scheme:
the integrated reversible fuel cell system comprises a single bifunctional fuel cell hydrogen production and power generation electric pile, a hydrogen circulation module, an oxygen circulation module and a water circulation module, wherein the single bifunctional fuel cell hydrogen production and power generation electric pile is called a fuel cell electric pile for short, the fuel cell electric pile comprises a plurality of single cells which are sequentially overlapped, a hydrogen inlet, a hydrogen outlet, an oxygen inlet, a cooling fluid inlet and a cooling fluid outlet, each single cell comprises a conductive plate and a membrane electrode, the hydrogen circulation module is connected with the hydrogen inlet and the hydrogen outlet of the fuel cell electric pile, the oxygen circulation module is connected with the oxygen inlet and the oxygen outlet of the fuel cell electric pile, the water circulation module is connected with the cooling fluid inlet and the cooling fluid outlet of the fuel cell electric pile, the forward process of the system uses oxyhydrogen gas to generate electricity, and the reverse process electrolyzes water to produce hydrogen;
when the power generation is carried out in the forward direction, the hydrogen circulation module and the oxygen circulation module respectively provide hydrogen and oxygen for the fuel cell stack, the water circulation module provides cooling water for the fuel cell stack, and the obtained electric energy is output through the conductive plate;
when hydrogen is produced by reversely electrolyzing water, the water circulation module provides an electrolyzed water raw material for the fuel cell stack, electric energy is introduced into the fuel cell stack for electrolyzing water through the external power supply of the conductive plate, and the prepared hydrogen and oxygen are stored through the hydrogen circulation module and the oxygen circulation module respectively. The hydrogen circulation module comprises a hydrogen gas-water separation device, a hydrogen gas storage device and a hydrogen circulation pipeline, wherein the hydrogen gas storage device is sequentially connected with the fuel cell stack and the hydrogen gas-water separation device through the hydrogen circulation pipeline and then is returned to be connected to the hydrogen gas storage device to form a loop; wherein the hydrogen-gas-water separation device is also connected to the hydrogen inlet of the fuel cell stack through a branch pipeline.
When the fuel cell stack is used for generating power in the forward direction, hydrogen is conveyed to a hydrogen inlet of the fuel cell stack by a hydrogen storage device through a circulating pipeline and enters the fuel cell stack, after the hydrogen participates in power generation in the fuel cell stack, the residual hydrogen and water vapor are conveyed to a hydrogen-gas-water separation device through a hydrogen outlet of the fuel cell stack, and the separated hydrogen returns to the hydrogen inlet of the fuel cell stack for recycling;
when the hydrogen is produced by reversely electrolyzing water, electric energy is introduced by the conductive plate to electrolyze water in the fuel cell stack, the produced hydrogen is sent out through a hydrogen outlet of the fuel cell stack and is sent to the hydrogen-gas-water separation device through the hydrogen circulation pipeline, and the hydrogen separated by the hydrogen-gas-water separation device is sent to the hydrogen gas storage device to be stored. The oxygen circulation module comprises an oxygen gas-water separation device, an oxygen gas storage device and an oxygen circulation pipeline, wherein the oxygen gas storage device is sequentially connected with the fuel cell stack and the oxygen gas-water separation device through the oxygen circulation pipeline and then is returned to be connected to the oxygen gas storage device to form a loop; wherein the oxygen gas-water separation device is also connected to the oxygen inlet of the fuel cell stack through a branch pipeline.
When the fuel cell stack is used for generating power in the forward direction, oxygen is conveyed to an oxygen inlet of the fuel cell stack by the oxygen storage device through the oxygen circulation pipeline and enters the fuel cell stack, after the oxygen participates in power generation in the fuel cell stack, a residual oxygen and water vapor mixture is conveyed to the oxygen-gas separation device through an oxygen outlet of the fuel cell stack, and the separated oxygen returns to the oxygen inlet of the fuel cell stack for recycling;
when hydrogen is produced by reversely electrolyzing water, electric energy is introduced by the conductive plate, oxygen and water vapor generated by electrolyzing water are sent out through an oxygen outlet of the fuel cell stack and are sent to the oxygen gas-water separation device through the oxygen circulation pipeline, and the separated oxygen is sent to the oxygen gas storage device for storage. The water circulation module comprises a first water tank, a heat exchanger and a water circulation pipeline, wherein the first water tank is sequentially connected with the oxygen-gas-water separation device, the heat exchanger and the fuel cell stack through the water circulation pipeline, then returns to the oxygen-gas-water separation device and finally returns to the first water tank; the first water tank is also connected with the hydrogen gas-water separation device through a water circulation pipeline.
When the power is generated in the forward direction, water in the first water tank sequentially passes through the oxygen-gas-water separation device, the heat exchanger and the fuel cell stack to be cooled, then flows out of a cooling liquid outlet of the fuel cell stack, passes through the oxygen-gas-water separation device and returns to the first water tank to form cooling water circulation; water separated by the hydrogen gas-water separation device and the oxygen gas-water separation device is conveyed to the first water tank through a water circulation pipeline;
when hydrogen is produced by reversely electrolyzing water, water in the first water tank passes through the oxygen-gas-water separation device and then flows through the heat exchanger, then is input into the fuel cell stack as an electrolysis raw material, and residual water after electrolysis flows out through a cooling liquid outlet of the fuel cell stack and then returns to the first water tank through the oxygen-gas-water separation device; and residual water vapor after electrolysis flows out through an oxygen outlet of the fuel cell stack, passes through the oxygen-gas-water separation device, returns to the first water tank, and is recycled.
The hydrogen gas-water separation device and the oxygen gas-water separation device both comprise a condensing device and a centrifugal separation device, the condensing device performs primary condensation on water vapor in the gas mixture, and the centrifugal separation device performs further separation on the gas-liquid mixture. The water circulation module has two functions of cooling and water supply, the hydrogen circulation module has two functions of hydrogen supply and hydrogen collection, and the oxygen circulation module has two functions of oxygen supply and oxygen collection.
The hydrogen production process by reverse electrolysis of water enables the produced hydrogen to have the pressure of 3-10 MPa.
The system is also provided with an oxyhydrogen pressure balancing device, and the oxyhydrogen pressure balancing device is arranged between a pipeline of the hydrogen gas-water separation device leading to the hydrogen gas storage cylinder and a pipeline of the oxygen gas-water separation device leading to the oxygen gas storage cylinder, is respectively connected with the two pipelines and balances the pressure between the two pipelines.
The pipeline of the hydrogen gas-water separation device leading to the hydrogen gas storage bottle is also provided with a hydrogen drier, the pipeline of the oxygen gas-water separation device leading to the oxygen gas storage bottle is provided with an oxygen drier, and water separated by the hydrogen drier and the oxygen drier is delivered to the low-pressure water tank.
Compared with the prior art, the invention has the following advantages:
1) the water, the hydrogen and the oxygen in the system are recycled in the whole system, so that the effective utilization of resources is realized, the process is environment-friendly, particularly the water recycling arrangement is adopted, the cooling water, the raw material water for electrolysis and the generated water in the power generation process of the fuel cell are brought into the water recycling, and the waste of water resources is effectively reduced;
2) the gas-water separation device is internally provided with a condenser and a centrifugal separator, so that water vapor, hydrogen and oxygen are separated more thoroughly, and later-stage compression, storage and reutilization of the hydrogen and the oxygen are facilitated;
3) the hydrogen production process can generate 3-10MPa of air pressure, and hydrogen does not need to be pressurized again, so that the working procedures are saved;
4) the first water tank is arranged to replenish water lost during circulation of the system.
Drawings
FIG. 1 is a schematic view of an integrated reversible fuel cell system according to the present invention;
FIG. 2 is a schematic diagram of the electrical power control system of the reversible fuel cell of the present invention;
FIG. 3 is a schematic diagram of a specific structure of the multifunctional container of the present invention;
in the figure, the position of the upper end of the main shaft,
1. a hydrogen gas cylinder; 2. an oxygen cylinder; 3. an integrated reversible fuel cell stack; 4. a hydrogen gas-water separation device; 5. a low pressure water tank; 6. a multifunctional container: an oxygen gas-water separation device, a cooling water and electrolysis reaction water tank, a fuel cell power generation product water collection device and a water-oxygen pressure balance container; 7. a heat exchanger; 8. a first pressure regulating valve; 9. a first isolation valve; 10. a hydrogen circulation fan; 11. a second pressure regulating valve; 12. an electrolytic water control valve; 13. a water circulating pump; 14. an oxygen circulation fan; 15. a second isolation valve; 16. a third isolation valve; 17 a fourth isolation valve; 18 an oxygen dryer; 19. a hydrogen gas dryer; 20. a hydrogen-oxygen pressure balancing subsystem (electrolysis); 21. a fifth isolation valve; 22. a first drain valve; 23. an electrolytic water replenishing pump; 24. a reversible fuel cell power electrical control system; 25. a sixth isolation valve; 26. a seventh isolation valve; 27.H2A pulse width modulation control valve; o282A pulse width modulation control valve; 29. a low pressure hydrogen storage vessel; 30. a low pressure oxygen storage vessel; 31 a hydrogen transfer compressor; 32. an oxygen delivery compressor; 33. a first check valve; 34. a second one-way valve; 35. a second drain valve; 101. a fuel cell power electronics module; 102. an electrolysis power supply module; 103. a power supply module of the supporting facility; 104. a system control module; 105. a power selection relay; 106. a battery; 201. a multi-functional container separating section; 202. a multi-functional container water tank portion; 203. a multifunctional container water level control sensor; 204. drainage electromagnetic valve selection switch (for burning)A fuel cell power generation process); 205. a water supply pump selection switch (electrolysis operation); 206. stabilize water level protection buffer.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
Examples
As shown in fig. 1, the system can realize forward hydrogen generation, convert chemical energy into electric energy, and can also realize reverse electrolysis water hydrogen production, convert electric energy into chemical energy, and when forward power generation and reverse hydrogen production are performed, hardware structures such as bipolar plates and membrane electrodes forming the integrated reversible fuel cell stack 3 and flow channel arrangement on the bipolar plates do not need to be changed, the same fuel cell system is adopted in the forward and reverse processes, the whole system is simple in arrangement, and cost is saved.
The system mainly comprises an integrated reversible fuel cell stack 3, a hydrogen circulation module, an oxygen circulation module and a water circulation module; the fuel cell stack 3 comprises a plurality of single cells which are sequentially overlapped, a hydrogen inlet and a hydrogen outlet, an oxygen inlet and a cooling fluid outlet, the single cells comprise a conductive plate and a membrane electrode, a hydrogen circulation module is connected with the hydrogen inlet and the hydrogen outlet of the integrated reversible fuel cell stack 3, the oxygen circulation module is connected with the oxygen inlet and the oxygen outlet of the integrated reversible fuel cell stack 3, and a water circulation module is connected with the cooling fluid inlet and the cooling fluid outlet of the integrated reversible fuel cell stack 3.
The integrated reversible fuel cell pile 3 is a core component for realizing forward power generation and reverse water electrolysis hydrogen production, converts chemical energy of hydrogen and oxygen into electric energy to be output during forward power generation, and externally connects a power supply with a conductive plate to electrolyze water to generate hydrogen and convert the electric energy into chemical energy during reverse water electrolysis hydrogen production;
the hydrogen circulating module is used for collecting and recycling hydrogen in the forward power generation process of the system and storing the prepared hydrogen when water is reversely electrolyzed to produce hydrogen;
the oxygen circulating module is used for collecting and recycling oxygen in the forward power generation process of the system and storing the prepared oxygen during reverse water electrolysis;
and the water circulation module realizes cooling water circulation in the forward power generation process, collects and stores water separated from the hydrogen circulation module and the oxygen circulation module, and supplies water and cooling water stored in the system together as raw materials for the electrolysis process when hydrogen is produced by reversely electrolyzing water.
The specific settings are as follows:
as shown in fig. 1, the integrated reversible fuel cell stack 3 includes a plurality of cells stacked in sequence, and a hydrogen inlet/outlet, an oxygen inlet/outlet, and a cooling fluid inlet/outlet, where the cells include a conductive plate and a membrane electrode, and the stack is connected to a reversible fuel cell power electrical control system 24.
The hydrogen circulation module include hydrogen gas water separator 4, hydrogen gas bomb 1 and hydrogen circulating line, hydrogen gas water separator 4 be equipped with hydrogen entry and hydrogen export, hydrogen gas bomb 1 passes through the hydrogen entry of the reversible fuel cell pile of integral type 3 of hydrogen circulating line connection, the hydrogen entry of the reversible fuel cell pile of integral type 3 of hydrogen exit linkage hydrogen gas water separator 4, hydrogen gas water separator 4's hydrogen export divide into two the tunnel, wherein connect hydrogen gas bomb 1 all the way, the hydrogen entry of the reversible fuel cell pile of integral type 3 is connected to another the tunnel. The hydrogen circulation pipeline is provided with a first pressure regulating valve 8, a first isolation valve 9, a fifth isolation valve 21, a sixth isolation valve 25 and a hydrogen circulation fan 10.
The oxygen circulation module include multi-functional container (oxygen gas-water separation device) 6, oxygen gas bomb 2 and oxygen circulating line, oxygen gas-water separation device be equipped with oxygen entry and oxygen export, oxygen gas bomb 2 passes through the oxygen entry that oxygen circulating line connects reversible fuel cell galvanic pile 3 of integral type, the oxygen entry of the reversible fuel cell galvanic pile 3's of integral type oxygen exit linkage oxygen gas-water separation device, oxygen gas-water separation device's oxygen export divide into two the tunnel, wherein connect oxygen gas bomb 2 all the way, the reversible fuel cell galvanic pile 3's of integral type oxygen entry is connected on another way. The oxygen circulating pipeline is provided with a second pressure regulating valve 11, a second isolation valve 15, a third isolation valve 16, a fourth isolation valve 17, a seventh isolation valve 26 and an oxygen circulating fan 14.
The water circulation module comprises a low-pressure water tank 5 (namely a first water tank), a multifunctional container (cooling water and electrolysis reaction water tank), a heat exchanger 7 and a water circulation pipeline, wherein the low-pressure water tank 5 is connected with the multifunctional container water tank part through an electrolysis water replenishing pump 23 at a first low-pressure water outlet, and the multifunctional container water tank part 202 is connected with the low-pressure water tank through a drain valve 22 at a first high-pressure water outlet. The multi-functional container water tank portion 202 is connected to the multi-functional container via a water circulation line in sequence after being connected to the heat exchanger and the integrated reversible fuel cell stack. The water outlet of the hydrogen gas-water separation device is connected to the low-pressure tank through a second drain valve 35. And the water outlets of the hydrogen dryer 19 and the oxygen dryer 18 in the hydrogen circulation module and the oxygen circulation module are also connected to the low-pressure water tank 5. And a circulating water pump 13 is arranged on the water circulating pipeline.
The system is also provided with an oxyhydrogen pressure balancing subsystem 20, when water is electrolyzed, the generated hydrogen is sent to the hydrogen gas storage bottle after passing through the hydrogen gas-water separation device, the generated oxygen is sent to the oxygen gas storage bottle after passing through the oxygen gas-water separation device, the oxyhydrogen pressure balancing subsystem 20 is arranged between a pipeline of the hydrogen gas-water separation device, which leads to the hydrogen gas storage bottle, and a pipeline of the oxygen gas-water separation device, which leads to the oxygen gas storage bottle, and is respectively connected with the two pipelines, when the system is used for electrolyzing water, the pressure between the hydrogen circulation pipeline and the oxygen circulation pipeline is balanced, thereby protecting the membrane electrode.
The hydrogen circulation module and the oxygen circulation module are respectively provided with a low-pressure hydrogen storage container 29 and a low-pressure oxygen storage container 30, and the inlet of the low-pressure hydrogen storage container 29 passes through H2The pulse width modulation control valve 27 is connected to a hydrogen circulation pipeline behind the hydrogen gas-water separation device, and the outlet of the pulse width modulation control valve is connected to the hydrogen inlet of the fuel cell stack through a hydrogen transfer compressor 31; inlet of low pressure oxygen storage vessel 30 is through O2After the pulse width modulation control valve 28 is connected with the oxygen gas-water separation deviceAnd the outlet of the oxygen circulating pipeline is connected with the oxygen inlet of the fuel cell stack through an oxygen delivery compressor.
The oxygen circulation line and the hydrogen circulation line are also provided with a first check valve 33 and a second check valve 34, which can increase the system equilibrium pressure at the beginning of the electrolysis cycle to the actual pressure level of the gas storage.
The specific principle is as follows:
as shown in fig. 1, at the time of electrolysis, electrolysis reaction water is supplied from a multi-functional container water tank portion 202 to an oxygen inlet of the integrated reversible fuel cell stack 3 via a circulating water pump 13 and an electrolysis water control valve 12 in order to supply water for electrolysis reaction to generate hydrogen and oxygen. As shown in fig. 3, cooling water is also supplied from the multi-function container water tank section 202 to the stack water inlet via the circulating water pump 13 in parallel with the flow of the electrolysis reaction water. The system control module 104, the utilities power module 103, and the electrolysis power module 102 apply power to the anode and cathode of the integrated reversible fuel cell stack 3 in a timely manner to drive the electrolysis of water, hydrogen and small amounts of water from the fuel cell stack H2The outlet end exits, and unreacted water and oxygen from the O of the integrated reversible fuel cell stack 32The outlet end exits. The liquid water is separated from H in the hydrogen gas-water separation device 42The gas is separated and discharged to the low pressure water tank 5 through the second drain valve 35. O is2And the unreacted water stream enters the multi-function vessel separation section 201 where the gas stream is separated from the water. The cooling water flow from the stack water outlet also enters the multi-functional vessel separation section 201. Both water flows fall under gravity through a small gap around the stable water level protection buffer 206 to the multi-functional container water tank part 202. Two air flows O2And H2Through the respective oxygen and hydrogen dryers 18 and 19 and the hydrogen-oxygen pressure equalization subsystem 20 (if required), are collected in the respective oxygen and hydrogen cylinders 2 and 1.
When pressure equilibrium is established in the two circuits, high pressure H2And O2The volume ratio of the gas spaces is about 2: 1. During electrolysis, the pressure of the two gases in the respective cylinders continuously increases as the electrolysis process proceeds. Water required for electrolytic reaction is multifunctionalThe water in the container 6 replenishes it, while the multi-functional container 6 is replenished with fresh water from a low-pressure water tank. As shown in fig. 3, the electrolytic makeup pump 23 is controlled by a multi-function container water level control sensor 203, i.e., a water supply pump selection switch 205 is kept off during the electrolysis process. A power selection relay (or contactor) 105 maintains the stack in connection with the electrolysis power module 102. When the pressure in both cylinders reaches the desired level or if H2And O2The system control module 104 stops electrolysis when the pressure difference between them exceeds a pressure difference safety design value, for example, a pressure difference of 1.5bar, the upper limit value of which depends on the integrated reversible fuel cell stack design. The membrane drying procedure is carried out until the electrolytic consumption power drops below the set point, for example: 0.1% of rated power. At this point, the fourth and fifth isolation valves 17, 21 are closed, and then the pressure in all circuits is gradually reduced to a desired value, for example: fuel cell operating pressure. H2Pulse width modulation control valves 27 and O2The pulse width modulation control valve 28 allows the pressure to be reduced, storing gas in the low pressure hydrogen storage vessel and the low pressure oxygen storage vessel, thereby allowing H2And O2The pressure difference between is kept below the desired value, for example: 0.5bar, the pressure difference value is less than the safe designed pressure difference value for controlling the system operation. The gas evacuated during the pressure reduction can be vented or stored in the low pressure hydrogen storage vessel 29 and the low pressure oxygen storage vessel 30.
After electrolysis is complete, all valves are closed and all pumps are deactivated, as shown in FIG. 2, with the power selection relay 105 in the neutral or fuel cell state position.
For power generation, H from the hydrogen and oxygen gas cylinders 1 and 2 and the low pressure hydrogen and oxygen gas storage vessels 29 and 30 (if used)2And O2The reaction gas reacts in the integrated reversible fuel cell stack 3 to produce H2And O, completing power generation. The fuel cell operates the utility assembly to activate and provide power to the customer. The battery 106 provides the starting power, the power selection relay 105 (or contactor) switches to the fuel cell state position, and the stack is connected to the fuel cell power electronics module 101. Fourth isolation valve 17 andthe five isolation valves 21 remain closed. A hydrogen transfer compressor 31 and an oxygen transfer compressor 32 are used to empty the low pressure hydrogen storage vessel 29 and the low pressure oxygen storage vessel 30 and to purge or purge the discharged or purified H2And O2Returning to the system. The high pressure of the reaction gas from the hydrogen cylinder 1 and the oxygen cylinder 2 is adjusted to the operating pressure of the fuel cell, for example, 1.5bar, by the first pressure regulating valve 8 and the second pressure regulating valve 11. Unreacted gas (100% of the stoichiometric reaction gas) from the outlet of the integrated reversible fuel cell stack 3 removes liquid water produced in the stack. These flows pass through the hydrogen gas-water separator 4 and the multi-function container 6 (oxygen gas-water separator), the separated water is discharged to the low-pressure water tank 5, the drain solenoid valve selector switch 204 is closed during power generation, and the gas is periodically or continuously recirculated to the integrated reversible fuel cell stack gas inlet via the hydrogen circulation fan 10 and the oxygen circulation fan 14. The recycle gas stream is mixed with the fresh reactant gas stream prior to entering the integrated reversible fuel cell stack 3. After fuel cell operation is complete, all valves are closed, all pumps and compressors are stopped, and the power selection relay 105 is in the neutral or electrolysis state position, as shown in fig. 2. This can be the start of the next electrolysis cycle or it can be prepared for a long period of time without the system being started, taking all the gas from H2And O2The circuit is discharged.
Water is added through the low-pressure water tank 5 in the process flow, and the water is used for supplementing the conditions of water consumption and the like in the forward power generation and reverse water electrolysis processes. Both water circuits (high pressure water circuit and low pressure water circuit) are used in electrolysis and fuel cell processes. In the high-pressure water circuit, the multifunctional tank water tank section 202 contains a relatively small amount of water, and the electrolytic reaction water during electrolysis is replenished from the low-pressure water tank 5 to the multifunctional tank water tank section 202 by the electrolytic replenishing water pump 23. The water pressure at the inlet of the circulating water pump 13 is automatically balanced with the oxygen outlet pressure of the galvanic pile in the multifunctional container 6. The same pump supplies the cooling water after heat exchange by the heat exchanger 7 or the electrolytic reaction water after heating to the two operation modes, respectively, and the electrolytic water control valve 12 opens to supply water for electrolysis. The fuel cell operation mode reaction product water is separated in the multi-functional container separation part 201. The excess water in the multi-function container tank section 202 is discharged to the low pressure tank 5 via the first drain valve 22. The heat exchanger 7 is used for cooling or heating.
The hydrogen gas-water separation device 4 and the oxygen gas-water separation device 6 are both provided with a condensing device and a centrifugal separation device, the condensing device performs primary condensation on water vapor in the gas-liquid mixture, and the centrifugal separation device further separates the gas-liquid mixture.
The hydrogen production process by reverse water electrolysis leads the produced hydrogen to have the pressure of 3-10MPa, and the hydrogen does not need to be compressed after hydrogen production, thus simplifying the process.
The electrolysis water replenishing pump 23 and the first drain valve 22 are controlled by water level signals in the oxygen gas-water separation device.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.