Electrolysis of water to produce hydrogen and co-produce chemicals, hydrogen dehydration system and process

Abstract

This invention discloses a hydrogen dehydration system and process for co-producing hydrogen and chemicals through water electrolysis. The top gas outlet of gas-water separator #1 is connected to the top gas inlet of the deoxygenation tower. The side gas outlet of the deoxygenation tower is connected to the tube-side inlet of cooler #1. The tube-side outlet of cooler #1 is connected to the inlet of gas-water separator #2. The outlet of gas-water separator #2 is connected to the tube-side inlet of cooler #2 via a hydrogen compressor. The tube-side outlet of cooler #2 is connected to the inlet of gas-water separator #3 via the tube-side of the product heater and the tube-side of the subcooler. The outlet of gas-water separator #3 is connected to the dehydration tower system via a process-controlled valve system. The compressor pressurizes and cools the hydrogen, and its potential energy removes a large amount of water from the hydrogen, achieving energy saving, emission reduction, reduced dehydrating agent loading, and lower production costs. This invention features a simple process, low operating costs, and full utilization of system potential energy and equipment, resulting in energy conservation and reduced consumption.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, specifically to a system and process for dehydrating hydrogen produced from water electrolysis and chemical products. Background Technology

[0002] Against the backdrop of low-carbon and zero-carbon energy transition, hydrogen is widely recognized as a significant contributor to global economic decarbonization, demonstrating enormous application potential in energy transition and serving as an energy carrier for integrating various infrastructures. Hydrogen production via water electrolysis plays a crucial role in global carbon reduction efforts. It not only provides a high-purity, zero-carbon emission hydrogen production method but also exhibits unparalleled environmental advantages compared to traditional fossil fuel-based hydrogen production methods, becoming a key technology for driving energy transition and achieving carbon neutrality. However, currently produced hydrogen contains a large amount of water, making the removal of this water a critical step. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned technical problems and provide a system and process for dehydrating hydrogen produced by electrolysis of water and chemical products, which can reduce energy consumption and production costs.

[0004] To achieve the above objectives, this invention provides a hydrogen dehydration system for co-producing chemicals through water electrolysis, comprising a #1 gas-water separator, a deoxygenation tower, a #1 cooler, a #2 gas-water separator, a hydrogen compressor, a #2 cooler, a product heater, a subcooler, and a #3 gas-water separator, as well as a dehydration tower system. The top gas outlet of the #1 gas-water separator is connected to the top gas inlet of the deoxygenation tower, the side gas outlet of the deoxygenation tower is connected to the tube-side inlet of the #1 cooler, the tube-side outlet of the #1 cooler is connected to the inlet of the #2 gas-water separator, the outlet of the #2 gas-water separator is connected to the tube-side inlet of the #2 cooler via the hydrogen compressor, the tube-side outlet of the #2 cooler is connected to the inlet of the #3 gas-water separator via the tube-side of the product heater and the tube-side of the subcooler, and the outlet of the #3 gas-water separator is connected to the dehydration tower system via a process control valve system. The hydrogen from the outlet of the dehydration tower system is delivered to the shell side of the product heater to recover cooling energy before being sent to downstream devices.

[0005] Furthermore, the dehydration tower system includes dehydration tower unit A, dehydration tower unit B, and dehydration tower unit C. Dehydration tower unit A includes a #4 gas-water separator, a #3 cooler, and a #A dehydration tower. Dehydration tower unit B includes a #5 gas-water separator, a #4 cooler, and a #B dehydration tower. Dehydration tower unit C includes a #6 gas-water separator, a #5 cooler, and a #C dehydration tower. One end of the #4 gas-water separator is connected to the outlet of the #3 gas-water separator via one channel of the #A programmable valve. The other end of the #4 gas-water separator is connected to one end of the #A dehydration tower via the tube side of the #3 cooler. The other end of the #A dehydration tower is connected to the shell side of the product heater via one channel of the #B programmable valve. One end of the #5 gas-water separator is connected to the #3 gas-water separator via one channel of the #C programmable valve. The outlet of the water separator is connected to the air-water separator. The other end of the #5 gas-water separator is connected to one end of the #4 dehydrator via the tube side of the #4 cooler. The other end of the #5 dehydrator is connected to the shell side of the product heater via the D# programmable valve. One end of the #6 gas-water separator is connected to the outlet of the #3 gas-water separator via the E# programmable valve. The other end of the #6 gas-water separator is connected to one end of the #C dehydrator via the tube side of the #5 cooler. The other end of the #C dehydrator is connected to the shell side of the product heater via the F# programmable valve. The other ends of the A#, C#, and E# programmable valves are interconnected. The other ends of the B#, D#, and F# programmable valves are also interconnected.

[0006] Furthermore, the dehydration tower system removes water from the hydrogen to 10 ppm and sends it to the downstream production unit in a sequential control of operation, regeneration, adsorption-adsorption, operation, regeneration-regeneration, adsorption, and operation.

[0007] Furthermore, the dehydrating agent in the A#, B#, and C# dehydration towers is regenerated using an electric heater, which uses green electricity.

[0008] Furthermore, the deoxygenation tower is equipped with an electric heater for deoxygenation, and the electric heater uses green electricity.

[0009] Furthermore, the cooling medium for both the #1 and #2 coolers is circulating water.

[0010] Furthermore, the cooling medium for the No. 3, No. 4 and No. 5 coolers is circulating water.

[0011] Furthermore, the inlet of the hydrogen compressor is also connected to a nitrogen pipeline.

[0012] A dehydration process for the dehydration system described above is also provided as follows:

[0013] Hydrogen from the water electrolysis hydrogen production unit is separated from water by the No. 1 gas-water separator and then deoxygenated by the deoxygenation tower. After being cooled by the No. 1 cooler, the hydrogen is separated from water by the No. 2 gas-water separator and then sent to the hydrogen compressor.

[0014] Hydrogen from the No. 2 gas-water separator is pressurized by the hydrogen compressor and then sent out. The hydrogen exiting the hydrogen compressor is cooled by the No. 2 cooler. After recovering its cooling capacity by the product gas heater, the hydrogen exiting the No. 2 cooler is cooled by the cooler and then enters the No. 3 gas-water separator to separate water. The hydrogen after water separation is sent to the dehydration tower system. The dehydration tower system removes water from the hydrogen by following a sequential control of operation, regeneration, adsorption-adsorption, operation, regeneration-regeneration, adsorption, and operation.

[0015] Furthermore, the hydrogen gas exiting the No. 3 gas-water separator enters the dehydration tower A unit via the A# programmable valve, sequentially passing through the No. 4 gas-water separator, the No. 3 cooler, and the A# dehydration tower to adsorb water from the hydrogen gas. The hydrogen gas exiting the A# dehydration tower is partially sent to the D# programmable valve in the dehydration tower B unit via the B# programmable valve, and the remaining portion is sent to downstream units after recovering its cooling capacity via the product gas heater, completing one dehydration cycle. The hydrogen gas passing through the D# programmable valve then enters the dehydration tower B unit, sequentially passing through the B# dehydration tower, the No. 4 cooler, and the No. 5 gas-water separator to complete the second dehydration process. The first dehydration process involves hydrogen gas entering dehydration tower unit C via the E# programmable valve to complete the third dehydration process, thus completing the operation, regeneration, and adsorption processes. Then, controlled by the programmable valve, the hydrogen gas exiting the #3 gas-water separator sequentially passes through dehydration tower unit B, dehydration tower unit C, and dehydration tower unit A to complete the adsorption, operation, and regeneration processes. Finally, controlled by the programmable valve again, the hydrogen gas exiting the #3 gas-water separator sequentially passes through dehydration tower unit C, dehydration tower unit A, and dehydration tower unit B to complete the regeneration, adsorption, and operation processes, thus completing a full dehydration process.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention fully utilizes the electrolysis of water to produce hydrogen and co-produce chemicals, uses a compressor to pressurize and cool the hydrogen, and utilizes the potential energy of the compressor to remove a large amount of water from the hydrogen, achieving the purpose of energy saving and emission reduction, reducing the amount of dehydrating agent filling and lowering production costs; the system structure of this invention is simple, the operation is flexible and convenient, the preparation investment and operating costs are low, and the system reliability is good; the process of this invention is simple, the operating cost is low, it can make full use of the system potential energy and equipment, save energy and reduce consumption, and is environmentally friendly; this invention is also applicable to processes that require hydrogen, such as electrolysis of water to produce hydrogen and co-produce liquid ammonia, electrolysis of water to produce hydrogen and co-produce methanol. Attached Figure Description

[0017] Figure 1 This is a flow chart of the electrolysis water hydrogen production and chemical dehydration system of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 The hydrogen dehydration system for co-producing chemicals by electrolysis of water shown includes a gas-water separator 1, a deoxygenation tower 2, a cooler 1 3, a gas-water separator 2 4, a hydrogen compressor 5, a cooler 2 6, a product heater 21, a subcooler 7, a gas-water separator 3 8, and a dehydration tower system. The top gas outlet of gas-liquid separator 1 is connected to the top gas inlet of deoxygenation tower 2. The side gas outlet of deoxygenation tower 2 is connected to the tube-side inlet of cooler 3. The tube-side outlet of cooler 3 is connected to the inlet of gas-liquid separator 4. The outlet of gas-liquid separator 4 is connected to the tube-side inlet of cooler 6 via hydrogen compressor 5. The tube-side outlet of cooler 6 is connected to the inlet of gas-liquid separator 8 via the tube-side of product heater 21 and the tube-side of subcooler 7. The outlet of gas-liquid separator 8 is connected to the dehydration tower system via a process control valve system. The hydrogen from the outlet of the dehydration tower system is sent to the shell side of product heater 21 to recover cold energy before being sent to downstream units.

[0020] The dehydration tower system includes dehydration tower unit A (9), dehydration tower unit B (13), and dehydration tower unit C (17). Dehydration tower unit A includes a #4 gas-water separator (10), a #3 cooler (11), and a #A dehydration tower (12). Similarly, dehydration tower unit B includes a #5 gas-water separator (14), a #4 cooler (15), and a #B dehydration tower (16). Dehydration tower unit C includes a #6 gas-water separator (18), a #5 cooler (19), and a #C dehydration tower (20). One end of the #4 gas-water separator (10) is connected to the outlet of the #3 gas-water separator (8) via one channel of the #A programmable valve (22). The other end of the #4 gas-water separator (10) is connected to one end of the #A dehydration tower (12) via the tube side of the #3 cooler (11). The other end of the #A dehydration tower (12) is connected to the shell side of the product heater (21) via one channel of the #B programmable valve (23). Similarly, one end of the #5 gas-water separator (14) is connected to the #3 gas-water separator (8) via one channel of the #C programmable valve (24). The outlet of water separator 8 is connected to the product heater 21. The other end of gas-water separator 14 is connected to one end of dehydration tower 16 via the tube side of cooler 15. The other end of dehydration tower 16 is connected to the shell side of product heater 21 via programmable valve 25. One end of gas-water separator 18 is connected to the outlet of gas-water separator 8 via programmable valve 26. The other end of gas-water separator 18 is connected to one end of dehydration tower 20 via the tube side of cooler 19. The other end of dehydration tower 20 is connected to the shell side of product heater 21 via programmable valve 27. The other ends of programmable valves 22, 24, and 26 are connected to each other. The other ends of programmable valves 23, 25, and 27 are also connected to each other. The three dehydration tower units remove water from the hydrogen to 10 ppm and send it to the downstream production unit in a sequential control of operation, regeneration, adsorption-adsorption, operation, regeneration-regeneration, adsorption, and operation, while the hydrogen is not lost.

[0021] In this embodiment, the dehydrating agent in dehydration tower 12 (A#), dehydration tower 16 (B#), and dehydration tower 20 (C#) is regenerated by an electric heater, which uses green electricity; the deoxygenation tower 2 is heated by an electric heater, which also uses green electricity.

[0022] The cooling medium for coolers #1 (3), #2 (6), #3 (11), #4 (15), and #5 (19) is circulating water, which is used to remove moisture from the system, reduce the load on the dehydration tower, and reduce the filling and consumption of dehydrating agent.

[0023] The cooling medium for subcooler 7 is selected according to the downstream unit. When producing liquid ammonia, liquid ammonia can be selected.

[0024] The deoxidizing agent in the deoxidation tower is a precious metal catalyst, while the dehydrating agent in all dehydration towers is a molecular sieve or other dehydrating agent.

[0025] Depending on the downstream chemicals, the nitrogen pipeline is connected to the inlet of hydrogen compressor 5.

[0026] Compared with traditional water electrolysis for hydrogen production, where hydrogen is first deoxygenated and then dehydrated before being sent to a compressor for pressurization and then to downstream devices, the present invention reduces the energy consumption of the device by compressing the hydrogen in the hydrogen compressor, then cooling it to remove a large amount of water, and finally sending it to the dehydration tower system for dehydration. At the same time, it reduces the amount of dehydrating agent required and lowers production costs.

[0027] Hydrogen gas from the water electrolysis hydrogen production unit (pressure 1.5 MPaG, temperature 80-90℃) is separated from water by gas-water separator 1, deoxygenated to 1 ppm by deoxygenation tower 2, cooled to 30-40℃ by cooler 1, and then sent to hydrogen compressor 5 after water is separated by gas-water separator 2.

[0028] Hydrogen from gas-water separator 4 (No. 2) and nitrogen from outside the boundary (a nitrogen supply line may or may not be installed depending on the downstream chemicals) are mixed and then pressurized by hydrogen compressor 5 before being sent out (pressure 2.5–3 MPaG). The hydrogen exiting compressor 5 is cooled to 30–40°C by cooler 6 (No. 2). After recovering its cooling capacity by product gas heater 21, the hydrogen is cooled to 4–5°C by cooler 7 before entering gas-water separator 8 (No. 3) to separate water. The hydrogen after water separation is then sent to the dehydration tower system. The potential energy of the hydrogen compressor is used to remove as much water as possible from the hydrogen, thereby reducing the amount of dehydrating agent required in the dehydration tower and saving production costs.

[0029] Hydrogen gas exiting gas-liquid separator 8 (#3) enters dehydration tower A unit 9 via A# programmable valve 22. It then passes through gas-liquid separator 10 (#4), cooler 11 (#3), and dehydration tower 9 (#5) to adsorb water from the hydrogen. Hydrogen gas exiting dehydration tower 9 is partially sent to dehydration tower B unit D# programmable valve 25 via B# programmable valve 23. The remaining portion is sent to downstream units after cooling is recovered by product gas heater 21, completing one dehydration cycle. Hydrogen gas passing through D# programmable valve 25 enters dehydration tower B unit 14, passing through dehydration tower B# 16, cooler 15 (#4), and gas-liquid separator 14 (#5) to complete a second dehydration cycle. Similarly, hydrogen gas passing through E# programmable valve... The hydrogen gas from valve 26 enters dehydration tower C unit 17 to complete the third dehydration process, thus completing the operation, regeneration, and adsorption processes. Then, controlled by a programmable valve, the hydrogen gas exiting gas-water separator 8 passes through dehydration tower B unit 14, dehydration tower C unit 17, and dehydration tower A unit 9 in sequence to complete the adsorption, operation, and regeneration processes. Finally, controlled by a programmable valve, the hydrogen gas exiting gas-water separator 8 passes through dehydration tower C unit 17, dehydration tower A unit 9, and dehydration tower B unit 14 in sequence to complete the regeneration, adsorption, and operation processes, thus completing a complete dehydration process, reducing the water content in the hydrogen gas to 10 ppm, and sending it to downstream devices without any hydrogen loss.

[0030] In this embodiment, the external nitrogen gas is adjusted or removed according to the specific chemicals being produced. The cooling medium for the cooler can be selected from options such as air coolers or evaporative coolers, depending on the actual needs of the plant, and the cooling temperature can be adjusted accordingly. The cooling medium for the subcooler can be selected from options such as chilled water supplied by a chiller unit, depending on the actual needs of the plant, and the cooling temperature can be adjusted accordingly. There are no specific limitations here; the goal is to remove as much water as possible from the hydrogen, based on the actual conditions of the plant, to reduce the amount of water entering the dehydration tower system.

[0031] The dehydration system of this invention can make full use of the chemical production from water electrolysis. In order to pressurize the hydrogen, the hydrogen produced by water electrolysis is first deoxygenated, cooled and separated into water, and then sent to the compressor inlet without being dehydrated. After being pressurized by the compressor, cooled and separated into water, it is sent to the dehydration system, thereby reducing the consumption of dehydrating agent and circulating water.

[0032] With 10000Nm 3 Taking the hydrogen produced by water electrolysis (pressure 1.5 MPaG, temperature 90°C) per hour as an example, the water content in the hydrogen gas after deoxygenation and cooling to 40°C is 28.63 kg. Using the process of this invention, 27.07 kg of water can be removed before entering the dehydration tower system, leaving only 1.56 kg of water which is dried to 10 ppm and sent to downstream units. The dehydrating agent is reduced from approximately 9.5 t to approximately 1.82 t, regeneration power consumption is reduced by 290 kWh, and the investment in the drying system is reduced from approximately 3.09 million yuan to approximately 2.72 million yuan. The economic benefits and energy-saving effects are significant. Simultaneously, the corresponding equipment size is reduced, facilitating layout and reducing civil engineering and installation costs.

Claims

1. A hydrogen dehydration system for electrolysis of water to produce hydrogen and co-produce chemicals, characterized in that: The system includes a gas-water separator (1), a deoxygenation tower (2), a cooler (3), a gas-water separator (4), a hydrogen compressor (5), a cooler (6), a product heater (21), a subcooler (7), and a gas-water separator (8), as well as a dehydration tower system; the top gas outlet of the gas-water separator (1) is connected to the top gas inlet of the deoxygenation tower (2), the side gas outlet of the deoxygenation tower (2) is connected to the tube-side inlet of the cooler (3), and the tube-side outlet of the cooler (3) is connected to the ... top gas inlet of the deoxygenation tower (4), a hydrogen compressor (5), a product heater (21), a subcooler (7), and a gas-water separator (8), as well as a dehydration tower system. The inlet of the gas-water separator (4) is connected, and the outlet of the gas-water separator (4) is connected to the inlet of the tube side of the cooler (6) via the hydrogen compressor (5). The outlet of the tube side of the cooler (6) is connected to the inlet of the gas-water separator (8) via the tube side of the product heater (21) and the tube side of the subcooler (7). The outlet of the gas-water separator (8) is connected to the dehydration tower system via the process control valve system. The hydrogen from the outlet of the dehydration tower system is sent to the shell side of the product heater (21) to recover the cold energy and then sent to the downstream unit.

2. The electrolysis water hydrogen production and chemical hydrogen dehydration system according to claim 1, characterized in that: The dehydration tower system includes dehydration tower unit A (9), dehydration tower unit B (13) and dehydration tower unit C (17). Dehydration tower unit A includes a 4# gas-water separator (10), a 3# cooler (11) and an A# dehydration tower (12). Dehydration tower unit B includes a 5# gas-water separator (14), a 4# cooler (15) and a B# dehydration tower (16). Dehydration tower unit C includes a 6# gas-water separator (18), a 5# cooler (19) and a C# dehydration tower (20). One end of the 4# gas-water separator (10) is connected to the outlet of the 3# gas-water separator (8) through one of the A# programmable valves (22). The other end of the 4# gas-water separator (10) is connected to one end of the A# dehydration tower (12) through the tube side of the 3# cooler (11). The other end of the A# dehydration tower (12) is connected to the shell side of the product heater (21) through one of the B# programmable valves (23). One end of gas-water separator 5 (14) is connected to the outlet of gas-water separator 3 (8) via one line of programmable valve C (24). The other end of gas-water separator 5 (14) is connected to one end of dehydration tower B (16) via the tube side of cooler 4 (15). The other end of dehydration tower B (16) is connected to the shell side of product heater (21) via programmable valve D (25). One end of gas-water separator 6 (18) is connected to the outlet of gas-water separator 3 (8) via one line of programmable valve E (26). The other end of the separator (18) is connected to one end of the C# dehydration tower (20) via the tube side of the 5# cooler (19). The other end of the C# dehydration tower (20) is connected to the shell side of the product heater (21) via one of the F# programmable valves (27). The other paths of the A# programmable valve (22), the C# programmable valve (24), and the E# programmable valve (26) are connected to each other. The other paths of the B# programmable valve (23), the D# programmable valve (25), and the F# programmable valve (27) are connected to each other.

3. The electrolysis water hydrogen production and chemical hydrogen dehydration system according to claim 2, characterized in that: The dehydration tower system removes water from hydrogen to 10 ppm and sends it to downstream production units by sequentially controlling the operation, regeneration, adsorption-adsorption, operation, regeneration-regeneration, adsorption, and operation.

4. The electrolysis water-to-hydrogen co-production and chemical hydrogen dehydration system according to claim 2, characterized in that: The dehydrating agent in the A# dehydration tower (12), B# dehydration tower (16) and C# dehydration tower (20) is regenerated by an electric heater, which uses green electricity.

5. The electrolysis water hydrogen production and chemical hydrogen dehydration system according to claim 1, characterized in that: The deoxygenation tower (2) is equipped with an electric heater for deoxygenation, and the electric heater uses green electricity.

6. The electrolysis water hydrogen production and chemical hydrogen dehydration system according to claim 1, characterized in that: The cooling medium for both the No. 1 cooler (3) and the No. 2 cooler (6) is circulating water.

7. The electrolysis water-to-hydrogen co-production and chemical hydrogen dehydration system according to claim 2, characterized in that: The cooling medium for the No. 3 cooler (11), No. 4 cooler (15) and No. 5 cooler (19) is circulating water.

8. The electrolysis water hydrogen production and chemical hydrogen dehydration system according to claim 1, characterized in that: The inlet of the hydrogen compressor (5) is also connected to a nitrogen pipeline.

9. A dehydration process for a dehydration system as described in any one of claims 1 to 8, characterized in that: The dehydration process is as follows: Hydrogen from the water electrolysis hydrogen production unit is separated from water by the No. 1 gas-water separator (1), then deoxygenated by the deoxygenation tower (2), and cooled by the No. 1 cooler (3). After being separated from water by the No. 2 gas-water separator (4), the hydrogen is sent to the hydrogen compressor (5). Hydrogen from the No. 2 gas-water separator (4) is pressurized by the hydrogen compressor (5) and then sent out. The hydrogen exiting the hydrogen compressor (5) is cooled by the No. 2 cooler (6). The hydrogen exiting the No. 2 cooler (6) recovers its cold energy by the product gas heater (21), and is then cooled by the cooler (7) before entering the No. 3 gas-water separator (8) to separate water. The hydrogen after water separation is sent to the dehydration tower system. The dehydration tower system removes water from the hydrogen by following the sequence of operation, regeneration, adsorption-adsorption, operation, regeneration-regeneration, adsorption, and operation.

10. The dehydration process according to claim 9, characterized in that: Hydrogen gas exiting the No. 3 gas-water separator (8) enters the dehydration tower A unit (9) via the A# programmable valve (22), and sequentially passes through the No. 4 gas-water separator (10), the No. 3 cooler (11), and the A# dehydration tower (12) to adsorb water from the hydrogen gas. Hydrogen gas exiting the A# dehydration tower (12) is partially sent to the D# programmable valve (25) of the dehydration tower B unit via the B# programmable valve (23), and the remaining part is sent to the downstream unit after recovering the cold energy through the product gas heater (21), completing one dehydration process. Hydrogen gas passing through the D# programmable valve (25) enters the dehydration tower B unit (13), and sequentially passes through the B# dehydration tower (16), the No. 4 cooler (15), and the No. 5 gas-water separator. (14) Complete the second dehydration process; all the hydrogen gas through the E# programmable valve (26) enters the dehydration tower C unit (17) to complete the third dehydration process; thus completing the operation, regeneration, and adsorption process; then, through the programmable valve control, the hydrogen gas exiting the 3# gas-water separator (8) passes through the dehydration tower B unit (13), dehydration tower C unit (17), and dehydration tower A unit (9) in sequence to complete the adsorption, operation, and regeneration process; finally, through the programmable valve control, the hydrogen gas exiting the 3# gas-water separator (8) passes through the dehydration tower C unit (17), dehydration tower A unit (9), and dehydration tower B unit (13) in sequence to complete the regeneration, adsorption, and operation process; thus completing a complete dehydration process.

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