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CN-122003521-A - Water recirculation loop for hydrogen-producing electrolysis device

CN122003521ACN 122003521 ACN122003521 ACN 122003521ACN-122003521-A

Abstract

The invention relates to a water recirculation circuit (30) for a hydrogen-producing electrolysis device (30) comprising an electrolysis stack (10). The water recirculation circuit (30) comprises at least one, preferably one, circulation pump (6), a water inlet section (9) connectable to the electrolysis stack (10), wherein the water inlet section (9) is capable of being supplied with water by the pump (6), a water supply section (91) leading to the water inlet section (9), a water outlet section (11) connectable to the electrolysis stack (10), wherein the water at the outlet section (11) is pressurized within the electrolysis stack (10) and/or in the water supply section (91) leading to the water inlet section (9), at least one energy recovery device (8, 28) for transferring water pressure and/or flow energy from the water outlet section (11) to the water supply section (91), and a recirculation section (31) connecting an output of the energy recovery device (8, 28) with an input port of the pump (6).

Inventors

  • H. Tucker Madsen
  • P. EUSTACE
  • M. Elk Yer Lautersen
  • A. Arora

Assignees

  • 格兰富控股公司

Dates

Publication Date
20260508
Application Date
20240916
Priority Date
20230922

Claims (20)

  1. 1. A water recirculation loop (30) for a hydrogen-producing electrolysis device (30) comprising an electrolysis stack (10), the water recirculation loop (30) comprising: at least one, preferably one circulation pump (6), A water inlet section (9) connectable to the electrolysis stack (10), wherein the water inlet section (9) is capable of being supplied with water by the pump (6), A water supply section (91) leading to the water inlet section (9), -A water outlet section (11) connectable to the electrolysis stack (10), wherein water at the outlet section (11) is pressurized within the electrolysis stack (10) and/or in the water supply section (91) leading to the water inlet section (9), -At least one energy recovery device (8, 28) for transferring water pressure and/or flow energy from the water outlet section (11) to the water supply section (91), and -A recirculation section (31) connecting the output of the energy recovery device (8, 28) with the input port of the pump (6).
  2. 2. The circuit (30) according to claim 1, wherein the water flow rate at the outlet section (11) is at least 85%, preferably at least 90%, more preferably at least 95% or even 98% of the water flow rate at the water inlet section (9).
  3. 3. The circuit (30) according to any of the preceding claims, wherein the water pressure at the water outlet section (11) is at least 30 bar, preferably at least 50 bar, more preferably at least 70 bar or even 100 bar.
  4. 4. The circuit (30) according to any of the preceding claims, wherein the water flow rate downstream of the pump (6) is at least 20m 3 /hour per MW electrolysis, preferably at least 100m 3 /hour per MW electrolysis, more preferably more than 200m 3 /hour per MW electrolysis.
  5. 5. The circuit (30) according to any one of the preceding claims, Wherein the pump (6) is designed so as not to leak substances harmful to the Proton Exchange Membrane (PEM) electrolyser (10), such as substances harmful to the proton exchange membrane, and/or Wherein the energy recovery device (8, 28) is designed to not leak electrode harmful substances harmful to Proton Exchange Membrane (PEM) electrolysers, Wherein the hazardous material is preferably one, more or all of the following: The metal cation(s) present in the composition, - CO 2 , -Organic matter.
  6. 6. The circuit (30) according to any one of the preceding claims, wherein the pump (6) is designed to not leak substances harmful to Alkaline Electrolysis (AEL) stacks, wherein the harmful substances are preferably one, more or all of the following: The presence of a polyvalent cation, The presence of a chloride compound, - CO 2 , -Organic matter.
  7. 7. The circuit (30) according to any one of the preceding claims, wherein the pump (6) is designed such that water pumped by the pump (6) can have ASTM type I quality and/or leak only substances harmless to ASTM type I water quality on both the upstream and downstream sides of the pump (6).
  8. 8. The circuit (30) according to any one of the preceding claims, Wherein the energy recovery device (8, 28) is designed so as not to leak out substances harmful to the electrolytic stack (10), such as substances harmful to the electrodes, the separator between the electrodes or the filter, such as an alkaline filter, and/or Wherein the energy recovery device (8, 28) is designed such that water passing through the energy recovery device (8, 28) has an ASTM type I quality and/or only leaks substances which are harmless to the ASTM type I water quality on both the upstream side and the downstream side of the energy recovery device (8, 28).
  9. 9. The circuit (30) according to any one of the preceding claims, wherein, The circuit is free of pressure control valves, e.g. pressure relief valves, downstream of the water outlet section (11), and/or The circuit is free of turbines downstream of the water outlet section (11).
  10. 10. The circuit (30) of any of the preceding claims, wherein the number of energy recovery devices arranged in parallel is greater than the number of pumps.
  11. 11. The circuit (30) according to any of the preceding claims, comprising a further pump (61), wherein preferably the water inlet section (9) and/or the water supply section (91) comprises the further pump (61).
  12. 12. The circuit (30) according to any of the preceding claims, wherein the energy recovery device (8, 28) comprises a pressure exchange unit (8) and/or a turbocharger (28).
  13. 13. The circuit (30) of any of the preceding claims, comprising a high pressure pump (62).
  14. 14. Circuit (30) according to claim 13, comprising a further water inlet section (63) connectable to the electrolysis stack (10), wherein the further water inlet section (63) is capable of being supplied with water by the pump (6) and arranged to bypass the energy recovery device (8, 28), and wherein the further water inlet section (63) comprises the high pressure pump (62).
  15. 15. The circuit (30) according to any of the preceding claims, preferably comprising a gas lift pump (70) in its water supply section (91).
  16. 16. The circuit (30) of claim 15, wherein the lift pump (70) includes an air supply port connectable to an oxygen output (81) configured to discharge oxygen formed in the electrolytic stack (10).
  17. 17. The circuit (30) according to claim 15 or 16, wherein the gas lift pump (70) comprises a water supply port connectable to a further water outlet section (16) configured to drain water discharged from the electrolysis stack (10) and preferably separate it from hydrogen by a hydrogen separator (14).
  18. 18. The circuit (30) according to any one of the preceding claims, Comprising an oxygen separator (80) connectable to the electrolysis stack (10), Wherein the oxygen separator (80) preferably comprises an oxygen output (81) configured to discharge oxygen formed in the electrolytic stack (10), And preferably also a pressure relief valve (90) connected to the oxygen separator (80).
  19. 19. The circuit (30) of claim 18, wherein a gas supply port of the gas lift pump (70) is connected to the oxygen output (81).
  20. 20. The circuit (30) of claim 18 or 19, wherein the oxygen separator (80) comprises a water output (82) configured to drain water discharged from the electrolytic stack (10), wherein the water output (82) is connected to the water outlet section (11).

Description

Water recirculation loop for hydrogen-producing electrolysis device Technical Field The present invention relates to a water recirculation loop for a hydrogen-producing electrolysis device. Background In the electrolysis of water, an electrolysis stack is used to split (ultrapure) water into oxygen and hydrogen by electrolysis. Subsequently, the hydrogen gas can be used as a hydrogen fuel. The electrolysis stack may be powered by renewable electricity. There are two commercial cell technologies, alkaline and Proton Exchange Membranes (PEM), and two under development, solid oxide cells (SOEC) and Anion Exchange Membranes (AEM). For alkalinity, PEM and AEM, water is liquid when subjected to electrolysis, and for SOEC, water is steam. A large amount of heat is generated in the process (200-250 kW per MW cell rating). To avoid excessive temperature rise across the stack, a large flow rate, for example 50-100 m 3/h per MW, is used. The water is pumped to the stack and then to a heat exchanger for cooling before returning to the stack. In the case of PEM and AEM there may be a side stream loop in which an ion exchange polisher is placed. The polisher ensures that the water remains clean continuously, thereby maintaining the life expectancy of the stack. Without this, the lifetime would be shortened, compromising the efficiency of the hydrogen plant, which is uneconomical. Hydrogen (hydrogen) is produced and then compressed in a compressor. To better handle fluctuating power inputs (e.g., from wind and solar energy) and to save costs, the hydrogen production plant may operate the electrolysis process under pressure. This would allow hydrogen to be produced at high pressure, eliminating or minimizing the need for a compressor. However, this requires that the circulation pump and the remaining process equipment, including the polisher, must be able to handle and withstand the high pressures. It is complicated to design components (pumps, polishers, etc.) to work at such high pressures (e.g., >40 bar). In particular, providing components dedicated to higher pressure levels is both expensive and difficult. It is therefore an object of the present invention to simplify the production of hydrogen. Disclosure of Invention The object of the invention is achieved by the solution provided in the independent claims. Advantageous embodiments of the invention are further defined in the dependent claims. According to a first aspect, the invention relates to a water recirculation loop for a hydrogen producing electrolysis device comprising an electrolysis stack, wherein the water recirculation loop comprises at least one, preferably one, circulation pump, a water inlet section connectable to the electrolysis stack, wherein the water inlet section can be supplied with water by the pump, a water supply section leading to the water inlet section, a water outlet section connectable to the electrolysis stack, wherein the water at the outlet section is pressurized within the electrolysis stack and/or in the water supply section leading to the water inlet section, at least one energy recovery device (e.g. a pressure exchange unit) for transferring water pressure and/or flow energy (flow energy) from the water outlet section to the water supply section, and a recirculation section connecting an output of the energy recovery device with an input port of the pump. This achieves the advantage that the energy recovery device is arranged to isolate certain components, for example with respect to high pressure and/or high flow energy. Thus, by means of the water recirculation loop, the benefits of both a high pressure and/or high flow configuration and a low pressure and/or low flow configuration may be obtained. For example, a high pressure configuration allows for reduced compression requirements, while a low pressure configuration allows for the use of components that do not need to withstand high pressures. Thus, in particular, simpler (e.g., less durable, less rigid, less complex, and/or less expensive) components may be used, and/or pressure and/or flow rate may be provided while maintaining the system at least partially designed for lower pressure and/or lower flow rate (e.g., pumps and/or devices for polishing water). Thereby, hydrogen production can be simplified. In the context of the present invention, "water" is understood to also include alkaline or acidic solutions. For example, in the context of the present invention, "water" may include water (H 2 O) containing 30 wt% or more of an alkaline substance, such as potassium hydroxide (KOH). In one embodiment, the water flow rate at the outlet section is at least 85%, preferably at least 90%, more preferably at least 95% or even 98% of the water flow rate at the water inlet section. In one embodiment the water pressure at the water outlet section is at least 30 bar, preferably at least 50 bar, more preferably at least 70 bar or even 100 bar. In one embodiment, the water flow rate do