Low-energy-consumption water replenishing structure for PEM hydrogen production, isobaric hydrogen production system and method

Abstract

The invention discloses a low-energy-consumption water replenishing structure for PEM hydrogen production and an isobaric hydrogen production system and method.In the low-energy-consumption water replenishing structure, the spatial position of a pure water storage tank is higher than that of a pure water replenishing tank, the pure water replenishing tank is higher than a pure water circulating tank, water replenishing can be conducted by means of gravity, extra pumping power is not needed, and in addition, the energy consumption is low; and the pressure generated by oxygen needing to be emptied is ingeniously utilized, so that the energy consumption of water replenishing of the pure water circulating tank can be greatly saved, the economical efficiency of green hydrogen preparation is increased, and the structural difficulty and cost of an isobaric hydrogen production system are further reduced. In the isobaric hydrogen production system, liquid water and hydrogen are separated out after hydrogen with water vapor reaches a hydrogen first-stage gas-water separation tank from a hydrogen outlet, the separated liquid water passes through a hydrogen second-stage gas-water separation tank, hydrogen is separated out under reduced pressure, and the liquid water is purified by a first deionized resin tank and then returns to a pure water storage tank, so that the purpose of saving water resources can be achieved.

Description

Technical Field

[0002] The present invention relates to the technical field of hydrogen production by water electrolysis using renewable energy, and in particular to a low-energy consumption water replenishment structure, an isobaric hydrogen production system and a method for PEM hydrogen production. Background Art

[0003] As a green secondary energy source, the large-scale application of green hydrogen can achieve zero carbon emissions and promote the transformation of the existing energy system to a newer and more optimized direction. The production of green hydrogen through large-scale renewable energy power generation will not only help solve the phenomenon of "abandoning wind and solar power" in my country, but also solve the problems of new energy consumption and grid connection stability, and achieve environmental sustainable development. PEM (proton exchange membrane) water electrolysis hydrogen production is one of the technical paths for water electrolysis hydrogen production. It has the characteristics of high working current density (>1 A / cm2), higher overall efficiency (74%~87%), higher hydrogen gas volume fraction (>99.99%), higher gas production pressure (3-4 MPa), faster dynamic response speed, and can adapt to the volatility of renewable energy power generation. It is considered to be a water electrolysis hydrogen production technology with great development prospects.

[0004] At present, the hydrogen production of a single PEM electrolysis stack produced in China is basically around 50-100Nm³ / h. In order to meet the demand for hydrogen production from renewable energy, the output of a single stack needs to be further improved. The hydrogen production of a single stack abroad has reached 1000Nm³ / h. However, the current mainstream PEM (proton exchange membrane) systems are mostly differential pressure forms, but the differential pressure system also has some unavoidable problems. One is that the strength of the membrane electrode proton membrane is limited, and the thickness is also affected by the supply of materials at home and abroad. The differential pressure has high requirements for the quality of the proton membrane, the structure of the PEM stack, and the assembly requirements. The maximum differential pressure of the current mainstream products is about 3MPa. Compared with the differential pressure system, the isobaric system can effectively reduce the strength of the proton membrane and the structural requirements of the PEM stack, and enhance the durability of the stack. The small-capacity hydrogen production BOP has low consumption of pure water, and only needs to use a diaphragm pump to replenish pure water. However, for the large-capacity BOP (Balance of Plant) system, it is difficult for the diaphragm pump or plunger pump to replenish water to meet the use requirements. Parallel diaphragm pumps or plunger pumps, or high-pressure centrifugal pump groups are costly, energy-intensive, complex in structure, and cannot be started and stopped frequently. How to reasonably and energy-efficiently replenish water for isobaric hydrogen production systems has become another technical challenge for high-power isobaric systems. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a low-energy consumption water replenishment structure for PEM hydrogen production.

[0006] To achieve the above purpose, the technical solution provided by the present invention is: A low-energy water replenishment structure for PEM hydrogen production, comprising a normal-pressure pure water storage tank, a variable-pressure pure water replenishment tank, and medium- and high-pressure pure water circulation tanks; The pure water storage tank is arranged above the pure water circulation tank, and a pure water machine is connected between the pure water storage tank and the tap water pipe; The pure water replenishment tank is arranged between the pure water storage tank and the pure water circulation tank, and the pure water replenishment tank is connected to the pure water storage tank and the pure water circulation tank through pipelines respectively, and the pure water replenishment tank is provided with an exhaust pressure relief component; A first water replenishment valve is provided on the pipeline between the pure water replenishment tank and the pure water storage tank; A second water replenishment valve and a pressure equalizing component are provided on the pipeline between the pure water replenishment tank and the pure water circulation tank; The pure water circulation tank is connected to the PEM stack to replenish water for the PEM stack and receive oxygen provided by the PEM stack, and the pure water circulation tank is provided with an oxygen regulating valve.

[0007] In this technical solution, the spatial position of the pure water storage tank is higher than the pure water make-up tank, and the pure water make-up tank is higher than the pure water circulating water tank. Water can be replenished by gravity without additional pumping power. In addition, the pressure generated by the need to exhaust oxygen is cleverly utilized, thereby greatly saving the energy consumption of pure water circulation tank water replenishment, increasing the economy of green hydrogen preparation, and further reducing the structural difficulty and cost of the isobaric hydrogen pressure system.

[0008] Furthermore, the present invention also provides an isobaric hydrogen production system, which includes the above-mentioned low-energy consumption water replenishment structure for PEM hydrogen production and a PEM stack; A pipeline for replenishing water for the PEM stack and a pipeline for supplying oxygen to the pure water circulation tank are provided between the pure water circulation tank and the PEM stack; A circulation pump and filter are provided on the pipeline for replenishing water for the PEM stack; A heat exchanger is provided on the pipeline that supplies oxygen to the pure water circulation tank.

[0009] Furthermore, the PEM stack is provided with a nitrogen purge inlet; The pure water storage tank is provided with a hydrogen in oxygen sensor.

[0010] Furthermore, it also includes a hydrogen primary gas-water separation tank, a hydrogen secondary gas-water separation tank, and a first deionization resin tank; The hydrogen primary gas-water separation tank is connected to the hydrogen outlet of the PEM stack through a pipeline; The hydrogen secondary gas-water separation tank is connected between the hydrogen primary gas-water separation tank and the first deionization resin tank; The first deionizing resin tank is connected to a pure water storage tank.

[0011] Furthermore, it also includes a second deionized resin tank, a deionized water return valve, a deionized branch current limiting gasket, and a deionized circulation switch valve; A water return pipe is provided between the pure water circulation tank and the pure water storage tank; From the pure water circulation tank to the pure water storage tank, the deionization circulation switch valve, the deionization branch current limiting gasket, the second deionization resin tank, and the deionized water return valve are sequentially arranged on the return pipe.

[0012] Furthermore, the present invention further provides an isobaric hydrogen production method, which is implemented by using the above-mentioned isobaric hydrogen production system, and comprises: The circulation pump is running to pump the pure water in the pure water circulation tank through the filter, PEM stack, and heat exchanger to return to the pure water circulation tank for gas-water separation. After the circulation pump is started and there is no abnormal signal failure, the electrolysis power supply is started to power the PEM stack; In the process of PEM stack producing hydrogen and oxygen, water is replenished through a low-energy water replenishment structure. During the water replenishment process, the pressure balance on the hydrogen side and the oxygen side is controlled, and the differential pressure on the two sides shall not exceed the set value until the pressure on the hydrogen side and the oxygen side of the system reaches the rated pressure.

[0013] Furthermore, the process of replenishing water through the low-energy water replenishment structure includes: When the pure water circulation tank is full of water, the pure water replenishment tank is discharged to normal pressure by adjusting the exhaust pressure relief component. Under the action of gravity, the pure water in the pure water storage tank flows into the pure water replenishment tank and fills up the pure water replenishment tank. During the process, the pure water machine replenishes the pure water storage tank according to the liquid level of the pure water storage tank. After the pure water replenishment tank is filled, close the first replenishment valve, adjust the exhaust pressure relief assembly, close the exhaust pressure relief, open the pressure equalization connecting pipeline branch solenoid valve, and transport the oxygen in the pure water circulation tank to the pure water replenishment tank, so that the pure water replenishment tank is pressurized to the same pressure as the pure water circulation tank, and adjust the oxygen regulating valve to output oxygen to the outside of the pure water circulation tank to maintain the pressure balance between the hydrogen side and the oxygen side; When the liquid level in the pure water circulation tank is as low as the water replenishment demand, open the pressure-equalizing connecting pipe ball valve and the second water replenishment valve at the same time, and use gravity to replenish the pure water in the pure water replenishment tank into the pure water circulation tank. After the pure water circulation tank is filled, close the second water replenishment valve, the pressure-equalizing connecting pipe branch solenoid valve and the pressure-equalizing connecting pipe ball valve; Open the pressure relief solenoid valve of the pure water make-up tank to release the pressure. After the pure water make-up tank is depressurized to normal pressure, open the exhaust valve and the first make-up valve to start the next round of water make-up cycle.

[0014] Furthermore, before the circulation pump is operated, nitrogen is purged into the system through the nitrogen purge inlet. After the nitrogen is purged, the concentration of hydrogen in oxygen in the system is detected by the hydrogen in oxygen sensor. If the concentration of hydrogen in oxygen is within the allowable range, the circulation pump is operated; otherwise, nitrogen continues to be purged into the system until the concentration of hydrogen in oxygen is within the allowable range.

[0015] Furthermore, the hydrogen generated from the PEM stack is hydrogen with water vapor. After the hydrogen with water vapor reaches the hydrogen primary gas-water separation tank from the hydrogen outlet, liquid water and hydrogen are separated. The separated liquid water then passes through the hydrogen secondary gas-water separation tank, decompresses and precipitates hydrogen, and then passes through the first deionization resin tank for purification before returning to the pure water storage tank, thereby achieving the purpose of saving water resources.

[0016] Furthermore, when the ion concentration of pure water in the pure water circulation tank is high, the ion concentration of pure water in the pure water circulation tank is reduced by replenishing water and / or returning water to the pure water storage tank; When returning water to the pure water storage tank, the deionized water return valve, the deionized branch current limiting gasket, and the deionized circulation switch valve cooperate to switch the return pipe and the pure water current limiting, thereby completing the pure water replacement through the second deionized resin tank and maintaining the ion concentration of the pure water in the pure water circulation tank at the set value.

[0017] Compared with the prior art, the principles and advantages of this technical solution are as follows: 1. The spatial position of the pure water storage tank is higher than that of the pure water make-up tank, and the pure water make-up tank is higher than the pure water circulating tank. Water can be replenished by gravity without additional pumping power. In addition, the pressure generated by the need to exhaust oxygen is cleverly utilized, thereby greatly saving the energy consumption of pure water circulation tank replenishment, increasing the economy of green hydrogen preparation, and further reducing the structural difficulty and cost of the isobaric hydrogen pressure system.

[0018] 2. After the hydrogen with water vapor reaches the hydrogen primary gas-water separation tank from the hydrogen outlet, liquid water and hydrogen are separated. The separated liquid water then passes through the hydrogen secondary gas-water separation tank, decompresses and precipitates hydrogen, and then passes through the first deionization resin tank for purification before returning to the pure water storage tank, thereby achieving the purpose of saving water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the services required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of a low energy consumption water replenishment structure for PEM hydrogen production according to the present invention; Figure 2 This is a schematic diagram of an isobaric hydrogenation system of the present invention.

[0021] Reference numerals: 1-pure water storage tank; 2-pure water replenishment tank; 3-pure water circulation tank; 4-exhaust valve; 5-pressure relief solenoid valve; 6-first water replenishment valve; 7-second water replenishment valve; 8-pressure equalizing connecting pipe branch solenoid valve; 9-pressure equalizing connecting pipe ball valve; 10-PEM stack; 11-circulation pump; 12-filter; 13-heat exchanger; 14-nitrogen purge inlet; 15-oxygen hydrogen sensor; 16-hydrogen primary gas-water separation tank; 17-hydrogen secondary gas-water separation tank; 18-first deionization resin tank; 19-second deionization resin tank; 20-deionized water return valve; 21-deionization branch current limiting gasket; 22-deionization circulation switch valve; 23-oxygen regulating valve; 24-pure water machine. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments: like Figure 1 As shown, a low-energy consumption water replenishment structure for PEM hydrogen production described in this embodiment includes a normal pressure pure water storage tank 1, a variable pressure pure water replenishment tank 2, and a medium and high pressure pure water circulation tank 3; Among them, the pure water storage tank 1 is arranged above the pure water circulation tank 3, and a pure water machine 24 is connected between the pure water storage tank 1 and the tap water pipe; the pure water make-up tank 2 is arranged between the pure water storage tank 1 and the pure water circulation tank 3, and the pure water make-up tank 2 is connected to the pure water storage tank 1 and the pure water circulation tank 3 through pipelines respectively, and the pure water make-up tank 2 is provided with an exhaust pressure relief component; a first make-up valve 6 (ball valve) is provided on the pipeline between the pure water make-up tank 2 and the pure water storage tank 1; a second make-up valve 7 (ball valve) and a pressure equalizing component are provided on the pipeline between the pure water make-up tank 2 and the pure water circulation tank 3; the pure water circulation tank 3 is connected to the PEM stack 10 to replenish the PEM stack 10 with water and receive oxygen provided by the PEM stack 10, and the pure water circulation tank 3 is provided with an oxygen regulating valve 23.

[0023] Specifically, the exhaust pressure relief component includes an exhaust valve 4 and a pressure relief solenoid valve 5, both of which are connected to the pipeline leading to the outside; the pressure equalizing component includes a pressure equalizing connecting pipeline branch solenoid valve 8 and a pressure equalizing connecting pipeline ball valve 9, and the pressure equalizing connecting pipeline branch solenoid valve 8 and the pressure equalizing connecting pipeline ball valve 9 are connected in parallel.

[0024] The principle of water replenishment through low-energy water replenishment structure is as follows: When the pure water circulation tank 3 is full of water, the pure water replenishment tank 2 is discharged to normal pressure by adjusting the exhaust pressure relief component. Under the action of gravity, the pure water in the pure water storage tank 1 flows into the pure water replenishment tank 2 and fills up the pure water replenishment tank 2. During the process, the pure water machine 24 replenishes the pure water storage tank 1 according to the liquid level of the pure water storage tank 1. After the pure water replenishment tank 2 is filled, the first replenishment valve 6 is closed, the exhaust pressure relief assembly is adjusted, the exhaust pressure relief is closed, and the pressure equalization connecting pipeline branch solenoid valve 8 is opened to transport the oxygen in the pure water circulation tank 3 to the pure water replenishment tank 2, so that the pure water replenishment tank 2 is pressurized to the same pressure as the pure water circulation tank 3, and the oxygen is output to the outside of the pure water circulation tank 3 by adjusting the oxygen regulating valve 23 to maintain the pressure balance between the hydrogen side and the oxygen side; When the liquid level of the pure water circulation tank 3 is as low as the water replenishment demand, open the pressure-equalizing connecting pipeline ball valve 9 and the second water replenishment valve 7 at the same time, and use gravity to replenish the pure water in the pure water replenishment tank 2 into the pure water circulation tank. After the pure water circulation tank is filled, close the second water replenishment valve 7, the pressure-equalizing connecting pipeline branch solenoid valve 8 and the pressure-equalizing connecting pipeline ball valve 9; The pressure relief solenoid valve 5 of the pure water replenishment tank 2 is opened to release the pressure. After the pure water replenishment tank 2 is depressurized to normal pressure, the exhaust valve 4 and the first water replenishment valve 6 are opened to carry out the next round of water replenishment cycle.

[0025] In the present embodiment, the spatial position of the pure water storage tank 1 is higher than the pure water replenishment tank 2, and the pure water replenishment tank 2 is higher than the pure water circulation tank. Water replenishment can be carried out by gravity without additional pumping power. In addition, the pressure generated by the need to exhaust oxygen is cleverly utilized, thereby greatly saving the energy consumption of replenishing water in the pure water circulation tank 3, increasing the economy of preparing green hydrogen, and further reducing the structural difficulty and cost of the isobaric hydrogen production system.

[0026] In addition, this embodiment also includes a isobaric hydrogenation system, such as Figure 2 As shown, it includes the above-mentioned low-energy water replenishment structure for PEM hydrogen production, a PEM stack 10, a hydrogen primary gas-water separation tank 16, a hydrogen secondary gas-water separation tank 17, a first deionization resin tank 18, a second deionization resin tank 19, a deionized water return valve 20, a deionization branch current limiting gasket 21, and a deionization circulation switch valve 22; Among them, a pipeline for replenishing water for the PEM battery stack 10 and a pipeline for supplying oxygen to the pure water circulation tank 3 are provided between the pure water circulation tank 3 and the PEM battery stack 10; a circulation pump 11 and a filter 12 are provided on the pipeline for replenishing water for the PEM battery stack 10; a heat exchanger 13 is provided on the pipeline for supplying oxygen to the pure water circulation tank 3.

[0027] The PEM stack 10 is provided with a nitrogen purge inlet 14 , and the pure water storage tank 1 is provided with an oxygen-hydrogen sensor 15 .

[0028] The primary hydrogen gas-water separation tank 16 is connected to the hydrogen outlet of the PEM stack 10 through a pipeline; the secondary hydrogen gas-water separation tank 17 is connected between the primary hydrogen gas-water separation tank 16 and the first deionization resin tank 18; the first deionization resin tank 18 is connected to the pure water storage tank 1.

[0029] A return water pipe is provided between the pure water circulation tank 3 and the pure water storage tank 1; from the pure water circulation tank 3 to the pure water storage tank 1, the deionization circulation switch valve 22, the deionization branch current limiting gasket 21, the second deionization resin tank 19, and the deionized water return valve 20 are sequentially arranged on the return water pipe.

[0030] The working principle of the isobaric hydrogenation system is as follows: Nitrogen is purged into the system through the nitrogen purge inlet 14. After the nitrogen purge is completed, the concentration of hydrogen in oxygen in the system is detected by the hydrogen in oxygen sensor 15. If the concentration of hydrogen in oxygen is within the allowable range, the circulation pump 11 is operated, otherwise, nitrogen is continuously purged into the system until the concentration of hydrogen in oxygen is within the allowable range. The oxygen in the system is replaced and discharged by purging nitrogen.

[0031] The circulation pump 11 is running (after the circulation pump 11 is running, the nitrogen purge is stopped), and the pure water in the pure water circulation tank is pumped through the filter 12, the PEM stack 10, and the heat exchanger 13 in sequence to return to the pure water circulation tank 3 for gas-water separation. After the circulation pump 11 is started and there is no abnormal signal failure, the electrolysis power supply is started to power the PEM stack 10; During the process of producing hydrogen and oxygen by the PEM stack 10, water is replenished through a low-energy consumption water replenishment structure. During the water replenishment process, the pressure balance on the hydrogen side and the oxygen side is controlled, and the differential pressure on the two sides shall not be higher than the set value until the pressure on the hydrogen side and the oxygen side of the system reaches the rated pressure.

[0032] The process of recharging water through a low-energy recharging structure includes: When the pure water circulation tank 3 is full of water, the pure water replenishment tank 2 is discharged to normal pressure by adjusting the exhaust pressure relief component. Under the action of gravity, the pure water in the pure water storage tank 1 flows into the pure water replenishment tank 2 and fills up the pure water replenishment tank 2. During the process, the pure water machine 24 replenishes the pure water storage tank 1 according to the liquid level of the pure water storage tank 1. After the pure water replenishment tank 2 is filled, the first replenishment valve 6 is closed, the exhaust pressure relief assembly is adjusted, the exhaust pressure relief is closed, and the pressure equalization connecting pipeline branch solenoid valve 8 is opened to transport the oxygen in the pure water circulation tank 3 to the pure water replenishment tank 2, so that the pure water replenishment tank 2 is pressurized to the same pressure as the pure water circulation tank 3, and the oxygen is output to the outside of the pure water circulation tank 3 by adjusting the oxygen regulating valve 23 to maintain the pressure balance between the hydrogen side and the oxygen side; When the liquid level of the pure water circulation tank 3 is as low as the water replenishment demand, open the pressure-equalizing connecting pipeline ball valve 9 and the second water replenishment valve 7 at the same time, and use gravity to replenish the pure water in the pure water replenishment tank 2 into the pure water circulation tank. After the pure water circulation tank is filled, close the second water replenishment valve 7, the pressure-equalizing connecting pipeline branch solenoid valve 8 and the pressure-equalizing connecting pipeline ball valve 9; The pressure relief solenoid valve 5 of the pure water replenishment tank 2 is opened to release the pressure. After the pure water replenishment tank 2 is depressurized to normal pressure, the exhaust valve 4 and the first water replenishment valve 6 are opened to carry out the next round of water replenishment cycle.

[0033] The hydrogen generated from the PEM stack 10 is hydrogen with water vapor. After the hydrogen with water vapor reaches the hydrogen primary gas-water separation tank 16 from the hydrogen outlet, liquid water and hydrogen are separated. The separated liquid water then passes through the hydrogen secondary gas-water separation tank 17, decompresses and precipitates hydrogen, and then passes through the first deionization resin tank 18 for purification before returning to the pure water storage tank 1.

[0034] When the pure water ion concentration in the pure water circulation tank 3 is high, the pure water ion concentration in the pure water circulation tank 3 is reduced by replenishing water and / or returning water to the pure water storage tank 1; When returning water to the pure water storage tank 1, the deionized water return valve 20, the deionized branch current limiting gasket 21, and the deionized circulation switch valve 22 cooperate to switch the return water pipeline and the pure water current limiting, thereby completing the pure water replacement through the second deionized resin tank 19 and maintaining the ion concentration of the pure water in the pure water circulation tank 3 at the set value.

[0035] In this embodiment, after the hydrogen with water vapor reaches the hydrogen primary gas-water separation tank 16 from the hydrogen outlet, liquid water and hydrogen are separated, and the separated liquid water then passes through the hydrogen secondary gas-water separation tank 17, decompresses and precipitates hydrogen, and then passes through the first deionization resin tank 18 for purification before returning to the pure water storage tank 1, thereby achieving the purpose of saving water resources.

[0036] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low energy consumption water replenishment structure for PEM hydrogen production, characterized in that: Including normal pressure pure water storage tank, variable pressure pure water replenishment tank, medium and high pressure pure water circulation tank; The pure water storage tank is arranged above the pure water circulation tank, and a pure water machine is connected between the pure water storage tank and the tap water pipe; The pure water replenishment tank is arranged between the pure water storage tank and the pure water circulation tank, and the pure water replenishment tank is connected to the pure water storage tank and the pure water circulation tank through pipelines respectively, and the pure water replenishment tank is provided with an exhaust pressure relief component; A first water replenishment valve is provided on the pipeline between the pure water replenishment tank and the pure water storage tank; A second water replenishment valve and a pressure equalizing component are provided on the pipeline between the pure water replenishment tank and the pure water circulation tank; The pure water circulation tank is connected to the PEM stack to replenish water for the PEM stack and receive oxygen provided by the PEM stack, and the pure water circulation tank is provided with an oxygen regulating valve.

2. An isobaric hydrogen production system, characterized in that: It includes the low-energy consumption water replenishment structure for PEM hydrogen production and the PEM stack as described in claim 1; A pipeline for replenishing water for the PEM stack and a pipeline for supplying oxygen to the pure water circulation tank are provided between the pure water circulation tank and the PEM stack; A circulation pump and filter are provided on the pipeline for replenishing water for the PEM stack; A heat exchanger is provided on the pipeline that supplies oxygen to the pure water circulation tank.

3. The isobaric hydrogenation system according to claim 2, characterized in that: The PEM stack is provided with a nitrogen purge inlet; The pure water storage tank is provided with a hydrogen in oxygen sensor.

4. The isobaric hydrogenation system according to claim 2, characterized in that: It also includes a hydrogen primary gas-water separation tank, a hydrogen secondary gas-water separation tank, and a first deionizing resin tank; The hydrogen primary gas-water separation tank is connected to the hydrogen outlet of the PEM stack through a pipeline; The hydrogen secondary gas-water separation tank is connected between the hydrogen primary gas-water separation tank and the first deionization resin tank; The first deionizing resin tank is connected to a pure water storage tank.

5. The isobaric hydrogenation system according to claim 2, characterized in that: It also includes a second deionized resin tank, a deionized water return valve, a deionized branch current limiting gasket, and a deionized circulation switch valve; A water return pipe is provided between the pure water circulation tank and the pure water storage tank; From the pure water circulation tank to the pure water storage tank, the deionization circulation switch valve, the deionization branch current limiting gasket, the second deionization resin tank, and the deionized water return valve are sequentially arranged on the return pipe.

6. A method for isobaric hydrogenation, characterized in that: The method is implemented by using the isobaric hydrogen pressure reduction system according to claim 2, which comprises: The circulation pump is running to pump the pure water in the pure water circulation tank through the filter, PEM stack, and heat exchanger to return to the pure water circulation tank for gas-water separation. After the circulation pump is started and there is no abnormal signal failure, the electrolysis power supply is started to power the PEM stack; In the process of PEM stack producing hydrogen and oxygen, water is replenished through a low-energy water replenishment structure. During the water replenishment process, the pressure balance on the hydrogen side and the oxygen side is controlled, and the differential pressure on the two sides shall not exceed the set value until the pressure on the hydrogen side and the oxygen side of the system reaches the rated pressure.

7. The isobaric hydrogenation method according to claim 6, characterized in that: The pressure equalizing component includes a pressure equalizing connecting pipeline branch solenoid valve and a pressure equalizing connecting pipeline ball valve, and the pressure equalizing connecting pipeline branch solenoid valve and the pressure equalizing connecting pipeline ball valve are connected in parallel; the exhaust pressure relief component includes an exhaust valve and a pressure relief solenoid valve, and the exhaust valve and the pressure relief solenoid valve are both connected to the pipeline leading to the outside; The process of recharging water through a low-energy recharging structure includes: When the pure water circulation tank is full of water, the pure water replenishment tank is discharged to normal pressure by adjusting the exhaust pressure relief component. Under the action of gravity, the pure water in the pure water storage tank flows into the pure water replenishment tank and fills up the pure water replenishment tank. During the process, the pure water machine replenishes the pure water storage tank according to the liquid level of the pure water storage tank. After the pure water replenishment tank is filled, close the first replenishment valve, adjust the exhaust pressure relief assembly, close the exhaust pressure relief, open the pressure equalization connecting pipeline branch solenoid valve, and transport the oxygen in the pure water circulation tank to the pure water replenishment tank, so that the pure water replenishment tank is pressurized to the same pressure as the pure water circulation tank, and adjust the oxygen regulating valve to output oxygen to the outside of the pure water circulation tank to maintain the pressure balance between the hydrogen side and the oxygen side; When the liquid level in the pure water circulation tank is as low as the water replenishment demand, open the pressure-equalizing connecting pipe ball valve and the second water replenishment valve at the same time, and use gravity to replenish the pure water in the pure water replenishment tank into the pure water circulation tank. After the pure water circulation tank is filled, close the second water replenishment valve, the pressure-equalizing connecting pipe branch solenoid valve and the pressure-equalizing connecting pipe ball valve; Open the pressure relief solenoid valve of the pure water make-up tank to release the pressure. After the pure water make-up tank is depressurized to normal pressure, open the exhaust valve and the first make-up valve to start the next round of water make-up cycle.

8. The isobaric hydrogenation method according to claim 6, characterized in that: The PEM stack is provided with a nitrogen purge inlet; the pure water storage tank is provided with an oxygen-hydrogen sensor; Before the circulation pump is operated, nitrogen is purged into the system through the nitrogen purge inlet. After the nitrogen is purged, the concentration of hydrogen in oxygen in the system is detected by the hydrogen in oxygen sensor. If the concentration of hydrogen in oxygen is within the allowable range, the circulation pump is operated, otherwise, nitrogen is continued to be purged into the system until the concentration of hydrogen in oxygen is within the allowable range.

9. The isobaric hydrogenation method according to claim 6, characterized in that: The isobaric hydrogenation system also includes a primary hydrogen gas-water separation tank, a secondary hydrogen gas-water separation tank, and a first deionization resin tank; the primary hydrogen gas-water separation tank is connected to the hydrogen outlet of the PEM stack through a pipeline; the secondary hydrogen gas-water separation tank is connected between the primary hydrogen gas-water separation tank and the first deionization resin tank; the first deionization resin tank is connected to a pure water storage tank; The hydrogen generated from the PEM stack is hydrogen with water vapor. After the hydrogen with water vapor reaches the hydrogen first-level gas-water separation tank from the hydrogen outlet, liquid water and hydrogen are separated. The separated liquid water then passes through the hydrogen second-level gas-water separation tank, decompresses and precipitates hydrogen, and then passes through the first deionization resin tank for purification before returning to the pure water storage tank.

10. The isobaric hydrogenation method according to claim 6, characterized in that: The isobaric hydrogenation system also includes a second deionized resin tank, a deionized water return valve, a deionized branch current limiting gasket, and a deionized circulation switch valve; a return pipe is provided between the pure water circulation tank and the pure water storage tank; from the pure water circulation tank to the pure water storage tank, the deionized circulation switch valve, the deionized branch current limiting gasket, the second deionized resin tank, and the deionized water return valve are sequentially arranged on the return pipe; When the ion concentration of pure water in the pure water circulation tank is high, the ion concentration of pure water in the pure water circulation tank is reduced by replenishing water and / or returning water to the pure water storage tank; When returning water to the pure water storage tank, the deionized water return valve, the deionized branch current limiting gasket, and the deionized circulation switch valve cooperate to switch the return pipe and the pure water current limiting, thereby completing the pure water replacement through the second deionized resin tank and maintaining the ion concentration of the pure water in the pure water circulation tank at the set value.

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