CN115595600A

CN115595600A - Water electrolysis device and method

Info

Publication number: CN115595600A
Application number: CN202110722639.0A
Authority: CN
Inventors: 章华勇; 李华云; 徐培莉; 张福顺
Original assignee: Air Products and Chemicals Inc
Current assignee: Air Products and Chemicals Inc
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2023-01-13

Abstract

The present invention relates to a water electrolysis apparatus and method. The device comprises an electrolytic bath for electrolyzing alkali liquor to generate hydrogen and oxygen; the hydrogen separator is used for flashing hydrogen generated by electrolysis and entrained alkali liquor; the oxygen separator is used for flashing oxygen generated by electrolysis and entrained alkali liquor; the hydrogen gradient separator is used for receiving and flashing the liquid phase flashed in the hydrogen separator; the oxygen gradient separator is used for receiving and flashing the liquid phase flashed in the oxygen separator; and a pipeline for mixing the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator and then returning the mixed liquid phase to the electrolytic tank, or a pipeline for respectively returning the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank.

Description

Water electrolysis device and method

Technical Field

The invention relates to a water electrolysis device and a method.

Background

The carbon dioxide emission reaches the peak value in China before 2030 years, and the carbon neutralization is realized before 2060 years, which is one of the key tasks in a period in the future in China. Actively exploring novel clean energy is helpful for accelerating carbon peak reaching and carbon neutralization work and accelerating optimization of industrial structure. Hydrogen energy is known as the ultimate energy in the 21 st century as a green energy with abundant reserves, high heat value, large energy density and various sources.

The hydrogen production by using renewable energy to electrolyze water is a new development trend of the hydrogen energy industry, and the hydrogen production link route is opened by using wind, light and water abandonment, so that energy waste can be avoided to the greatest extent, the economy of hydrogen production by electrolyzing water is improved, and the sustainable development requirement of green energy is met.

The green energy sources such as wind energy and light energy can not continuously provide stable electric energy output, which is very much testful for the operation of the high-pressure water electrolysis device. Because the hydrogen solubility in the oxygen product gas can be greatly increased to be close to the explosion lower limit concentration when the medium-high pressure water electrolysis device operates at low load or low current density, huge safety risk is brought to the medium-high pressure water electrolysis operation. Therefore, how to safely utilize wind energy and light energy on the medium and high water electrolysis device is a problem to be solved.

The traditional medium-high pressure water electrolysis device is generally only provided with a hydrogen separator and an oxygen separator, and the operating pressure is 10-30bar. When the load or current density of the water electrolyser is too low, for example at start-up and shut-down or when the sudden power input is greatly reduced, there is a sharp increase in the hydrogen content of the crude oxygen product gas.

Disclosure of Invention

The invention aims to provide a water electrolysis device and a method, which solve the safety problem caused by the operation of a traditional medium/high pressure water electrolysis device at low current density and ensure the pressure of hydrogen and oxygen products to avoid generating fluctuation on a downstream device. When the water electrolyzer runs under the working condition of low current density, the alkali liquor is subjected to multi-gradient pressure operation. And (3) discharging the gas dissolved in the alkali liquor out of the alkali liquor circulating system, reducing the hydrogen content in the oxygen product gas, and ensuring that the concentration of hydrogen in oxygen is lower than the lower explosion limit, thereby realizing the safe production of the medium/high pressure water electrolysis device in low current density operation. The operation area of the medium-high pressure water electrolysis device is greatly expanded, and the safety and reliability of the operation of the medium-high pressure water electrolysis device are improved.

The invention provides a water electrolysis device, which comprises

An electrolytic cell for electrolyzing the alkali liquor to produce hydrogen and oxygen;

the hydrogen separator is used for flashing hydrogen generated by electrolysis and entrained alkali liquor;

the oxygen separator is used for flashing oxygen generated by electrolysis and entrained alkali liquor;

the hydrogen gradient separator is used for receiving and flashing the liquid phase flashed in the hydrogen separator;

the oxygen gradient separator is used for receiving and flashing the liquid phase flashed in the oxygen separator; and

and the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator is mixed and then returns to the pipeline of the electrolytic tank, or the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator respectively returns to the pipeline of the electrolytic tank.

The invention also provides a water electrolysis device, which comprises

An electrolytic cell for electrolyzing the alkali solution to produce hydrogen and oxygen;

the gradient separator is used for receiving and flashing the liquid phase after flashing in the hydrogen separator and the liquid phase after flashing in the oxygen separator; and

a line returning the liquid phase after flash evaporation of the gradient separator to the electrolyzer.

The invention also provides a water electrolysis method, which comprises

Electrolyzing the alkali liquor through an electrolytic cell to produce hydrogen and oxygen;

hydrogen and entrained alkali liquor generated by the flash evaporation and electrolysis of the hydrogen separator;

oxygen generated by flash evaporation and electrolysis through an oxygen separator and entrained alkali liquor;

receiving and flashing the liquid phase flashed in the hydrogen separator through a hydrogen gradient separator;

receiving and flashing the liquid phase flashed in the oxygen separator through an oxygen gradient separator; and

and mixing the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator and then returning the mixture to the electrolytic tank, or respectively returning the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank.

The invention also provides a water electrolysis method, which comprises

Electrolyzing the lye through an electrolytic cell to produce hydrogen and oxygen;

hydrogen generated by flash evaporation and electrolysis through a hydrogen separator and entrained alkali liquor;

receiving and flashing the liquid phase flashed in the hydrogen separator and the liquid phase flashed in the oxygen separator through a gradient separator; and

and returning the liquid phase after flash evaporation of the gradient separator to the electrolytic tank.

Automatically adjusting the operation pressure of the alkali liquor according to different loads or current densities. The gas dissolved in the alkali liquor can be discharged out of the circulating system, so that the oxygen content in the hydrogen product and the hydrogen content in the oxygen product gas are reduced. The purpose of safe production is achieved.

The invention adopts a gradient pressure process on the traditional medium-high pressure water electrolysis device, can expand the load fluctuation range of the water electrolysis cell to a range of 15-100 percent under the condition of ensuring the stable operation pressure of hydrogen and oxygen product gas of the medium-high pressure water electrolysis device, and the hydrogen concentration in the crude oxygen product gas is still lower than 2 percent. The safety of the wide operation of the medium-high pressure water electrolyzer can be greatly improved, and a safe technical scheme is provided for directly utilizing unstable green energy such as wind energy or solar energy and the like as the energy input of the water electrolyzer.

Drawings

FIG. 1 is a diagram of a water electrolysis apparatus according to one embodiment of the present invention;

FIG. 2 is a diagram of a water electrolysis apparatus according to another embodiment of the present invention;

FIG. 3 is a diagram of a water electrolysis apparatus according to another embodiment of the present invention.

Detailed Description

In one aspect, the invention relates to a water electrolysis apparatus comprising

In one aspect, the water electrolysis apparatus further comprises

The hydrogen scrubber is used for washing off alkali liquor carried in the hydrogen after flash evaporation in the hydrogen separator and generating crude hydrogen; and/or

And the oxygen scrubber is used for washing off alkali liquor carried in the oxygen after flash evaporation in the oxygen separator and generating crude oxygen.

In one aspect, the water electrolysis apparatus further comprises

A line to replenish water consumed by the production of hydrogen and oxygen.

In one aspect, the water electrolysis apparatus further comprises

The purge hydrogen scrubber is used for washing off alkali liquor carried in the hydrogen after flash evaporation in the hydrogen gradient separator and generating hydrogen purge gas; and/or

And the purge oxygen scrubber is used for washing alkali liquor carried in the oxygen after the flash evaporation in the oxygen gradient separator and generating oxygen purge gas.

In one aspect, the apparatus includes a line for returning the liquid phase after the flashing of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic cell after mixing, and a circulation flow regulating valve is included in the line.

In one aspect, the apparatus comprises lines for returning the liquid phase after the flashing of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank, respectively, and a circulation flow regulating valve is included in the line for returning the liquid phase after the flashing of the hydrogen gradient separator to the electrolytic tank and/or the line for returning the liquid phase after the flashing of the oxygen gradient separator to the electrolytic tank.

In one aspect, the water electrolysis apparatus further comprises

A liquid phase equilibrium tube between the hydrogen gradient separator and the oxygen gradient separator.

In one aspect, the operating pressure of the cell is in the range of 10 to 30barg.

In one aspect, the hydrogen separator and the oxygen separator are operated at a pressure of 10-30bar.

In one aspect, the hydrogen gradient separator and the oxygen gradient separator are operated at a pressure of 1 to 30barA.

In one aspect, the operating pressure of the hydrogen and oxygen gradient separators is maintained by the gas phase flashed off from the hydrogen and oxygen gradient separators, or by the gas phase flashed off from the hydrogen and oxygen separators, or by an inert gas. Such as nitrogen.

In one aspect, further comprising a circulation pump downstream of the hydrogen and/or oxygen gradient separator and upstream of the electrolysis cell.

In one aspect, further comprising a circulating lye cooler downstream of the hydrogen gradient separator and/or the oxygen gradient separator and upstream of the circulating flow regulating valve, wherein the circulating flow regulating valve opening is adjusted by a circulating lye cooler hot end temperature difference.

a line for returning the liquid phase after flashing by the gradient separator to the electrolysis cell.

In one aspect, the water electrolysis apparatus further comprises

And the oxygen scrubber is used for washing alkali liquor carried in the oxygen after flash evaporation in the oxygen separator and generating crude oxygen.

In one aspect, the water electrolysis apparatus further comprises

A line to replenish water consumed by the production of hydrogen and oxygen.

In one aspect, the water electrolysis apparatus further comprises

And the purge gas scrubber is used for washing alkali liquor carried in the gas after flashing in the gradient separator and generating purge gas.

In one aspect, the line returning the liquid phase after flashing of the gradient separator to the electrolysis cell comprises a circulation flow regulating valve.

In one aspect, the gradient separator is operated at a pressure of 1 to 5barA.

In one aspect, the operating pressure of the gradient separator is maintained by the gas phase flashed off by the gradient separator, or by the gas phase flashed off by the hydrogen separator and the oxygen separator, or by an inert gas. Such as nitrogen.

In one aspect, further comprising a circulation pump downstream of the gradient separator and upstream of the electrolyzer.

In one aspect, further comprising a circulating lye cooler downstream of the gradient separator and upstream of the circulating flow control valve, wherein the circulating flow control valve opening is adjusted by a circulating lye cooler hot end temperature differential.

In one aspect, the invention relates to a method of water electrolysis comprising

In one aspect, the method of water electrolysis further comprises

Washing off alkali liquor carried in the hydrogen after flash evaporation in the hydrogen separator by using a hydrogen scrubber to generate crude hydrogen; and/or

Washing out alkali liquor carried in the oxygen after flash evaporation in the oxygen separator by an oxygen scrubber to generate crude oxygen.

In one aspect, the method of water electrolysis further comprises

Replenishing water consumed by the production of hydrogen and oxygen.

In one aspect, the method of water electrolysis further comprises

Washing off alkali liquor carried in the hydrogen after flash evaporation in the hydrogen gradient separator by a purge hydrogen scrubber and generating hydrogen purge gas; and/or

Washing out alkali liquor carried in the oxygen after flashing in the oxygen gradient separator by a purge oxygen scrubber and generating oxygen purge gas.

In one aspect, the method of water electrolysis further comprises

Controlling the circulation amount of the alkali liquor by a circulation flow regulating valve in a pipeline which returns the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank after mixing, wherein when the load or the current density of the water electrolysis device is reduced, the circulation amount of the alkali liquor is reduced.

In one aspect, the method of water electrolysis further comprises

And controlling the circulation amount of the alkali liquor by a circulation flow regulating valve contained in a pipeline returning the liquid phase after the flash evaporation of the hydrogen gradient separator to the electrolytic tank and/or a circulation flow regulating valve contained in a pipeline returning the liquid phase after the flash evaporation of the oxygen gradient separator to the electrolytic tank, wherein the circulation amount of the alkali liquor is reduced when the load or current density of the water electrolysis device is reduced.

In one aspect, the method of water electrolysis further comprises

The pressure difference between the cathode and anode cells of the electrolyzer is reduced by a liquid phase balance tube between the hydrogen gradient separator and the oxygen gradient separator.

In one aspect, the hydrogen gradient separator and oxygen gradient separator are operated at a pressure of 1 to 30barA.

In one aspect, the operating pressure of the hydrogen gradient separator is adjusted according to the liquid level difference of the hydrogen gradient separator and the oxygen gradient separator.

In one aspect, the operating pressure of the hydrogen gradient separator and/or the oxygen gradient separator is adjusted according to the electrolyzer operating load or current density.

In one aspect, wherein the operating pressure of the hydrogen gradient separator and oxygen gradient separator is maintained by the gas phase flashed off by the hydrogen gradient separator and oxygen gradient separator, or by the gas phase flashed off by the hydrogen separator and oxygen separator, or by an inert gas. Such as nitrogen.

In one aspect, the method of water electrolysis further comprises circulating the lye through a circulation pump downstream of the hydrogen and/or oxygen gradient separator and upstream of the electrolysis cell.

In one aspect, the water electrolysis method further comprises cooling the lye by a circulating lye cooler downstream of the hydrogen gradient separator and/or the oxygen gradient separator and upstream of the circulating flow regulating valve, wherein the circulating flow regulating valve opening is adjusted by a warm end temperature difference of the circulating lye cooler.

Electrolysis of the lye by means of an electrolysis cell to produce hydrogen and oxygen:

carrying out flash evaporation on oxygen generated by electrolysis and the entrained alkali liquor through an oxygen separator;

In one aspect, the method of water electrolysis further comprises

Washing out alkali liquor carried in the oxygen after flash evaporation in the oxygen separator by an oxygen scrubber and generating crude oxygen.

In one aspect, the method of water electrolysis further comprises

Replenishing water consumed by the production of hydrogen and oxygen.

In one aspect, the method of water electrolysis further comprises

The lye entrained in the gas after flashing in the gradient separator is washed away by a purge gas scrubber and a purge gas is produced.

In one aspect, the method of water electrolysis further comprises

The circulation amount of the alkali liquor is controlled by a circulation flow regulating valve contained in a pipeline returning the liquid phase after the flash evaporation of the gradient separator to the electrolytic tank.

In one aspect, the gradient separator is operated at a pressure of 1 to 5barA.

In one aspect, the operating pressure of the gradient separator is adjusted according to the electrolysis cell operating load or current density.

In one aspect, wherein the operating pressure of the gradient separator is maintained by the gas phase flashed off from the gradient separator, or by the gas phase flashed off from the hydrogen separator and the oxygen separator, or by an inert gas. Such as nitrogen.

In one aspect, the method of water electrolysis further comprises circulating the lye through a circulation pump downstream of the gradient separator and upstream of the electrolytic cell.

In one aspect, the method of water electrolysis further comprises cooling the lye by a circulating lye cooler downstream of the gradient separator and upstream of the circulating flow control valve, wherein the circulating flow control valve opening is adjusted by a temperature differential at the hot end of the circulating lye cooler.

In one aspect, after the liquid phase enters the gradient separator, hydrogen and oxygen in the gas phase produced by the flash of the gradient separator are diluted with an inert gas. Such as nitrogen.

In one aspect, a hydrogen gradient separator and an oxygen gradient separator are provided on the liquid phase flow path of the hydrogen separator and the oxygen separator, respectively, and the dissolved gas concentration in the lye is reduced by differently controlling the oxygen gradient separator pressure. Typically the hydrogen and oxygen gradient separator pressure operation can be controlled between 1 and 30bar. Therefore, under the working condition of extremely low operating load or low current density, the hydrogen content in the crude oxygen product gas is reduced, and the safe production of the water electrolysis device in a wide operating area is improved. Because the hydrogen separator, the oxygen separator, the hydrogen gradient separator and the oxygen gradient separator are arranged at the same time, the operation pressure of the hydrogen separator and the oxygen separator under any working condition can be ensured to be unchanged even under the working condition of low load or low current density, and the operation pressure of the crude hydrogen product gas and the crude oxygen product gas can be maintained to be stable and unchanged under any working condition. The water electrolysis device adopting the gradient pressure process can safely operate under the working conditions of low load or low current density for a long time. The feasibility and the utilization rate of the wind energy and the solar energy as the energy of the water electrolysis device are improved, and the safety risk caused by frequent shutdown of the water electrolysis device due to instability of the wind energy and the solar energy is also reduced.

In one aspect, a lye circulation flow regulating valve is provided in the flow path of lye back to the water electrolysis cell to reduce lye circulation flow and reduce the flow of hydrogen and oxygen through the circulating lye into the cathode and anode cells of the water electrolysis cell as the load or current density of the water electrolysis cell is reduced, thereby reducing the hydrogen content of the raw oxygen product gas and improving the safe production of the water electrolysis cell over a wide operating area. The circulation amount of the alkali liquor can be adjusted according to the temperature difference of the hot side of the alkali liquor circulation cooler. The circulation amount of the alkali liquor can be adjusted in a 10-100% load interval.

In one aspect, a liquid phase balance tube is disposed between the hydrogen gradient separator and the oxygen gradient separator. Therefore, the diaphragm can be prevented from being damaged by overlarge pressure difference between the cathode and the anode small chamber of the water electrolysis cell, and the risk of high hydrogen concentration in the crude oxygen product gas caused by damage of the diaphragm is reduced.

In one aspect, the operating pressures of the hydrogen and oxygen gradient separators may be set in response to the operating load or current density of the water electrolysis cell to ensure that the operating pressures of the hydrogen and oxygen gradient separators may respond to changes in load or current density instantaneously.

Examples

Example 1

Refer to fig. 1. The alkali liquor is pressurized to 10-30barg required by the electrolytic bath A-101 by a circulating pump P-101 and then respectively enters a cathode chamber and an anode chamber of the electrolytic bath A-101. Under the action of electric energy and negative/positive electrode, water in the alkali liquor is decomposed to produce hydrogen and oxygen in the cathode chamber and the anode chamber respectively. Hydrogen and oxygen generated by decomposition enter the hydrogen separator V-101 and the oxygen separator V-102 respectively along with the alkali liquor to be flashed. The operating pressure of the hydrogen separator V-101 and the oxygen separator V-102 is 10-30bar. And the gas phase flashed by the hydrogen separator V-101 is sent to a hydrogen scrubber W-101, the gas phase flashed by the oxygen separator V-102 is sent to an oxygen scrubber W-102, and desalted water is adopted to scrub the alkali liquor removed from the hydrogen and the oxygen. While at the same time replenishing the water consumed by the production of hydrogen and oxygen and maintaining the lye concentration at this level.

The crude hydrogen product gas and the crude oxygen product gas are obtained after being washed by a hydrogen washer W-101 and an oxygen washer W-102 and are sent to a downstream refining section.

The liquid phase after flash evaporation in the hydrogen separator V-101 enters a hydrogen gradient separator V-103 for flash evaporation. The flash-evaporated gas phase is discharged from the purge hydrogen scrubber S-101, and is sent to a safe place to be discharged after being separated from the entrained alkali liquor. The operating pressure of the hydrogen gradient separator V-103 can be adjusted according to the liquid level difference of the hydrogen gradient separator V-103 and the oxygen gradient separator V-104. The pressure may be controlled to operate in the range of 1 to 30barA. The hydrogen content in the alkali liquor is reduced due to the effect of decompression flash evaporation.

The liquid phase after flash evaporation in the oxygen separator V-102 enters the oxygen gradient separator V-104 for flash evaporation. The flash evaporated gas phase is discharged to a safe place after being discharged with alkali liquor after being removed by a purge oxygen scrubber S-102. The operating pressure of the oxygen gradient separator V-104 can be adjusted according to the operating load or current density of the water electrolyzer A-101. The pressure may be controlled between 1 and 30barA. Due to the effect of decompression flash evaporation, the oxygen content in the alkali liquor is reduced.

Liquid phases which are flashed by the hydrogen gradient separator V-103 and the oxygen gradient separator V-104 are mixed and then sent to an alkali liquor cooler E-101 for cooling to 70-90 ℃, and then sent to an alkali liquor circulating pump P-101.

An alkali liquor circulation flow regulating valve FV-101 is arranged on a pipeline from the circulation pump P-101 to the water electrolyzer A-101 and is used for controlling the circulation amount of the alkali liquor. When the load or current density of the water electrolysis device is reduced, the circulation amount of the alkali liquor is reduced by reducing the opening degree of the alkali liquor circulation flow regulating valve FV-101.

In order to avoid excessive pressure difference between the cathode and anode cells of the water electrolyzer, a liquid phase equilibrium tube is arranged between the hydrogen gradient separator V-103 and the oxygen gradient separator V-104.

The medium-high pressure water electrolysis device of the embodiment 1 has the load fluctuation range which can be expanded to the range of 15-100%, and the hydrogen concentration in the crude oxygen product gas is still lower than 2%.

Example 2:

refer to fig. 2. The oxygen-containing alkali liquor is pressurized to the operating pressure of 10-30barg required by the electrolytic bath A-101 through an anode alkali liquor circulating pump P-101 and then enters a cathode chamber of the electrolytic bath A-101. The hydrogen-containing alkali liquor is pressurized to the operating pressure of 10-30barg required by the electrolytic bath A-101 by a cathode alkali liquor circulating pump P-102 and then enters an anode chamber of the electrolytic bath A-101. Under the action of electric energy and negative/positive electrode, water in alkali liquor is decomposed to produce hydrogen and oxygen in the cathode and anode chambers respectively. By the method, the problem of the solution difference polarization of the water electrolysis device can be solved.

Hydrogen and oxygen generated by decomposition enter the hydrogen separator V-101 and the oxygen separator V-102 respectively along with the alkali liquor to be flashed. The operation pressure of the hydrogen separator V-101 and the oxygen separator V-102 is 10-30bar. And the gas phase flashed by the hydrogen separator V-101 is sent to the hydrogen scrubber W-101, the gas phase flashed by the oxygen separator V-102 is sent to the oxygen scrubber W-102, and desalted water is used for scrubbing alkali liquor removed from the hydrogen and the oxygen. While at the same time replenishing the water consumed by the production of hydrogen and oxygen and maintaining the concentration of the lye at this concentration.

The liquid phase after flash evaporation through the hydrogen separator V-101 enters a hydrogen gradient separator V-103 for flash evaporation. The flash evaporated gas phase is discharged from the purge hydrogen scrubber S-101 with entrained alkali liquor and then is sent to a safe place for discharge. The operating pressure of the hydrogen gradient separator V-103 can be adjusted according to the liquid level difference of the hydrogen gradient separator V-103 and the oxygen gradient separator V-104. The pressure may be controlled to operate in the range 1 to 30barA. The hydrogen content in the alkali liquor is reduced due to the effect of decompression flash evaporation.

The liquid phase after flash evaporation in the oxygen separator V-102 enters the oxygen gradient separator V-104 for flash evaporation. The flash evaporated gas phase is discharged to a safe place after being discharged with alkali liquor after being removed by a purge oxygen scrubber S-102. The operating pressure of the oxygen gradient separator V-104 can be adjusted depending on the operating load or current density of the water electrolyzer A-101. The pressure may be controlled between 1 and 30barA. Due to the effect of decompression flash evaporation, the oxygen content in the alkali liquor is reduced.

Liquid phase from the hydrogen gradient separator V-103 is sent to a cathode alkali liquor cooler E-101 for cooling to 70-90 ℃, and then sent to a cathode alkali liquor circulating pump P-101.

Liquid phase from the oxygen gradient separator V-104 is sent to an anode lye cooler E-102 to be cooled to 70-90 ℃, and then sent to an anode lye circulating pump P-102.

In order to avoid excessive pressure difference between the cathode and anode chambers of the water electrolyzer, a liquid phase balance pipe is arranged between the hydrogen gradient separator V-103 and the oxygen gradient separator V-104.

An anode lye circulating flow regulating valve FV-101 and a cathode lye circulating flow regulating valve FV-102 are arranged on the pipelines from the anode lye circulating pump P-101 and the cathode lye circulating pump P-102 to the water electrolyzer A-101 and are used for controlling the lye circulating amount. When the load or current density of the water electrolysis device is reduced, the circulation amount of the alkali liquor is reduced by reducing the opening of the anode alkali liquor circulation flow regulating valve FV-101 and the cathode alkali liquor circulation flow regulating valve FV-102.

The medium-high pressure water electrolysis device of the embodiment 2 has the load fluctuation range which can be expanded to the range of 25-100%, and the hydrogen concentration in the crude oxygen product gas is still lower than 2%.

Example 3:

refer to fig. 3. The alkali liquor is pressurized to 10-30barg required by the electrolytic bath A-101 by a circulating pump P-101 and then respectively enters a cathode chamber and an anode chamber of the electrolytic bath A-101. Under the action of electric energy and negative/positive electrode, water in the alkali liquor is decomposed to produce hydrogen and oxygen in the cathode chamber and the anode chamber respectively. Hydrogen and oxygen generated by decomposition enter the hydrogen separator V-101 and the oxygen separator V-102 respectively along with the alkali liquor to be flashed. The operating pressure of the hydrogen separator V-101 and the oxygen separator V-102 is 10-30bar. And the gas phase flashed by the hydrogen separator V-101 is sent to a hydrogen scrubber W-101, the gas phase flashed by the oxygen separator V-102 is sent to an oxygen scrubber W-102, and desalted water is adopted to scrub the alkali liquor removed from the hydrogen and the oxygen. While at the same time replenishing the water consumed by the production of hydrogen and oxygen and maintaining the concentration of the lye at this concentration.

The crude hydrogen product gas and the crude oxygen product gas are washed by a hydrogen washer W-101 and an oxygen washer W-102 and are sent to a downstream refining section.

The liquid phase after flash evaporation and mixing through the hydrogen separator V-101 and the oxygen separator V-102 is divided into two flow paths. During normal operation, all the lye directly enters the circulating lye cooler E-101. When the current density is lower or the hydrogen content in the oxygen product gas is higher than 1-2%, all the alkali liquor enters a gradient separator V-103 for flash evaporation. The flash-evaporated gas phase is discharged to a safe place after being separated from the entrained alkali liquor by a purge gas scrubber S-101. The operating pressure of the gradient separator V-103 can be controlled to operate in the range of 1 to 5barA. The hydrogen content in the alkali liquor is reduced due to the effect of decompression flash evaporation. Meanwhile, when the alkali liquor enters the gradient separator V-103, the nitrogen valve FV-103 is opened to dilute the concentration of oxygen and hydrogen in the flash gas phase of the gradient separator V-103. The two alkali liquors are finally combined together and enter a circulating alkali liquor cooler E-101.

The alkali liquor cooled by the circulating cooler E-101 is sent to a circulating alkali liquor pump P-101 to be pressurized to the operating pressure 10-30barg required by the water electrolyzer. The alkali liquor after being pressurized is sent to a water electrolysis bath A-101 after the flow of the alkali liquor is adjusted by an alkali liquor circulation flow adjusting valve FV-101.

The middle-high pressure water electrolysis device of the embodiment 3 has the load fluctuation range which can be expanded to the range of 15-100%, and the hydrogen concentration in the crude oxygen product gas is still lower than 2%.

The invention comprises the following technical scheme.

1. A water electrolysis apparatus comprising

2. The water electrolysis apparatus of claim 1 further comprising

3. The water electrolysis apparatus of claim 1 further comprising

A line to replenish water consumed by the production of hydrogen and oxygen.

4. The water electrolysis apparatus of claim 1 further comprising

And the purge oxygen scrubber is used for washing alkali liquor carried in the oxygen after flash evaporation in the oxygen gradient separator and generating oxygen purge gas.

5. The water electrolysis apparatus according to claim 1, wherein

The device comprises a pipeline which leads the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator to be mixed and then return to the electrolytic tank, and the pipeline comprises a circulating flow regulating valve.

6. The water electrolysis apparatus according to claim 1, wherein

The device comprises a pipeline for returning the liquid phase flashed by the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank respectively, and a circulation flow regulating valve is arranged in the pipeline for returning the liquid phase flashed by the hydrogen gradient separator to the electrolytic tank and/or the pipeline for returning the liquid phase flashed by the oxygen gradient separator to the electrolytic tank.

7. The water electrolysis apparatus of claim 1 further comprising

8. The water electrolysis apparatus of claim 1 wherein the operating pressure of the electrolytic cell is between 10 and 30barg.

9. The water electrolysis apparatus of claim 1 wherein the operating pressure of the hydrogen separator and the oxygen separator is 10-30bar.

10. The water electrolysis apparatus of claim 1 wherein the hydrogen gradient separator and oxygen gradient separator are operated at a pressure of 1 to 30barA.

11. The water electrolysis apparatus according to claim 1, wherein the operating pressure of the hydrogen gradient separator and the oxygen gradient separator is maintained by the gas phase flashed off from the hydrogen gradient separator and the oxygen gradient separator, or by the gas phase flashed off from the hydrogen separator and the oxygen separator, or by an inert gas.

12. The water electrolysis apparatus of claim 1 further comprising a circulation pump downstream of the hydrogen and/or oxygen gradient separators and upstream of the electrolyzer.

13. The water electrolysis device according to claim 5 or 6, further comprising a circulating alkali cooler downstream of the hydrogen gradient separator and/or the oxygen gradient separator and upstream of the circulating flow regulating valve, wherein the opening degree of the circulating flow regulating valve is regulated by the temperature difference of the hot end of the circulating alkali cooler.

14. A water electrolysis apparatus comprising

15. The water electrolysis apparatus of claim 14 further comprising

16. The water electrolysis apparatus of claim 14 further comprising

A line to replenish water consumed by the production of hydrogen and oxygen.

17. The water electrolysis apparatus of claim 14 further comprising

And the purge gas scrubber is used for washing off alkali liquor carried in the gas after flashing in the gradient separator and generating purge gas.

18. The water electrolysis apparatus of claim 14 wherein

The pipeline for returning the liquid phase after flash evaporation of the gradient separator to the electrolytic bath comprises a circulating flow regulating valve.

19. The water electrolysis apparatus of claim 14 wherein the operating pressure of the electrolytic cell is between 10 and 30barg.

20. The water electrolysis apparatus of claim 14 wherein the hydrogen separator and oxygen separator are operated at a pressure of 10-30bar.

21. The water electrolysis apparatus according to claim 14 wherein the operating pressure of the gradient separator is between 1 and 5barA.

22. The water electrolysis apparatus of claim 14 wherein the operating pressure of the gradient separator is maintained by the gas phase flashed off from the gradient separator, or by the gas phase flashed off from the hydrogen separator and the oxygen separator, or by an inert gas.

23. The water electrolysis apparatus of claim 14 further comprising a circulation pump downstream of the gradient separator and upstream of the electrolyzer.

24. The water electrolysis apparatus of claim 18, further comprising a circulating lye cooler downstream of the gradient separator and upstream of the circulating flow control valve, wherein the opening of the circulating flow control valve is adjusted by a temperature difference at a hot end of the circulating lye cooler.

25. A method of water electrolysis comprising

26. The method of water electrolysis according to claim 25 further comprising

27. The method of water electrolysis according to claim 25 further comprising

Replenishing water consumed by the production of hydrogen and oxygen.

28. The method of water electrolysis of claim 25 further comprising

Washing off alkali liquor carried in the hydrogen after flashing in the hydrogen gradient separator and generating hydrogen purge gas by a purge hydrogen scrubber; and/or

Washing off alkali liquor carried in the oxygen after flashing in the oxygen gradient separator by a purge oxygen scrubber and generating oxygen purge gas.

29. The method of water electrolysis of claim 25 further comprising

And controlling the circulation amount of the alkali liquor by a circulation flow regulating valve in a pipeline which returns the liquid phase after the flash evaporation of the hydrogen gradient separator and the oxygen gradient separator to the electrolytic cell after mixing, wherein when the load or the current density of the water electrolysis device is reduced, the circulation amount of the alkali liquor is reduced.

30. The method of water electrolysis according to claim 25 further comprising

31. The method of water electrolysis of claim 25 further comprising

32. The process of water electrolysis according to claim 25 wherein the operating pressure of the electrolytic cell is in the range 10 to 30barg.

33. The method of water electrolysis according to claim 25 wherein the operating pressure of the hydrogen separator and oxygen separator is 10-30bar.

34. The process for electrolysis of water according to claim 25 wherein the hydrogen gradient separator and oxygen gradient separator are operated at a pressure of 1 to 30barA.

35. The method of water electrolysis according to claim 25 wherein the operating pressure of the hydrogen gradient separator is adjusted according to the level difference between the hydrogen gradient separator and the oxygen gradient separator.

36. The method of water electrolysis according to claim 25 wherein the operating pressure of the hydrogen gradient separator and/or the oxygen gradient separator is adjusted according to the electrolyzer operating load or current density.

37. The method of water electrolysis according to claim 25 wherein the operating pressure of the hydrogen and oxygen gradient separators is maintained by the gas phase flashed off from the hydrogen and oxygen gradient separators or by the gas phase flashed off from the hydrogen and oxygen separators or by an inert gas.

38. The method of water electrolysis according to claim 25, further comprising circulating the lye through a circulation pump downstream of the hydrogen and/or oxygen gradient separator and upstream of the electrolysis cell.

39. The method of water electrolysis according to claim 29 or 30, further comprising cooling the lye by a circulating lye cooler downstream of the hydrogen and/or oxygen gradient separator and upstream of the circulation flow regulating valve, wherein the opening of the circulation flow regulating valve is adjusted by a temperature difference at the hot end of the circulating lye cooler.

40. A method of water electrolysis comprising

41. The method of water electrolysis of claim 40 further comprising

42. The method of water electrolysis of claim 40 further comprising

Replenishing water consumed by the production of hydrogen and oxygen.

43. The method of water electrolysis of claim 40 further comprising

44. The method of water electrolysis of claim 40 further comprising

45. The method of water electrolysis according to claim 40 wherein the operating pressure of the electrolytic cell is in the range 10 to 30barg.

46. The method of water electrolysis according to claim 40, wherein the operating pressure of the hydrogen separator and the oxygen separator is 10-30bar.

47. The method of water electrolysis according to claim 40 wherein the operating pressure of the gradient separator is between 1 and 5barA.

48. The method of water electrolysis according to claim 40 wherein the operating pressure of the gradient separator is adjusted according to the cell operating load or current density.

49. The method of water electrolysis according to claim 40 wherein the operating pressure of the gradient separator is maintained by the gas phase flashed off from the gradient separator or by the gas phase flashed off from the hydrogen separator and the oxygen separator or by an inert gas.

50. The method of water electrolysis according to claim 40 further comprising circulating the lye through a circulation pump downstream of the gradient separator and upstream of the electrolytic cell.

51. The method of water electrolysis according to claim 44, further comprising cooling the lye by a circulating lye cooler downstream of the gradient separator and upstream of the circulating flow control valve, wherein the circulating flow control valve opening is adjusted by a temperature differential at the hot end of the circulating lye cooler.

52. The method of water electrolysis according to claim 40 wherein the hydrogen and oxygen in the gas phase produced by the flash evaporation of the gradient separator are diluted with an inert gas after the liquid phase enters the gradient separator.

Although the present invention has been described in connection with the preferred embodiments illustrated in the accompanying drawings, it will be understood that various modifications are possible within the spirit and scope of the invention.

Claims

1. A water electrolysis apparatus comprises

2. The water electrolysis apparatus of claim 1 further comprising

3. The water electrolysis apparatus of claim 1 further comprising

A line for replenishing water consumed by the production of hydrogen and oxygen.

4. The water electrolysis apparatus of claim 1 further comprising

5. The water electrolysis apparatus of claim 1 wherein

The device comprises a pipeline which returns the liquid phase after the liquid phase is flashed by the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank after being mixed, and the pipeline comprises a circulation flow regulating valve.

6. The water electrolysis apparatus of claim 1 wherein

The device comprises a pipeline for returning liquid phases flashed by the hydrogen gradient separator and the oxygen gradient separator to the electrolytic tank respectively, and a circulating flow regulating valve is arranged in the pipeline for returning the liquid phases flashed by the hydrogen gradient separator to the electrolytic tank and/or the pipeline for returning the liquid phases flashed by the oxygen gradient separator to the electrolytic tank.

7. The water electrolysis apparatus of claim 1 further comprising

8. The water electrolysis apparatus of claim 1 wherein the operating pressure of the electrolytic cell is in the range 10 to 30barg.

9. The water electrolysis device of claim 1 wherein the operating pressure of the hydrogen and oxygen separators is 10-30bar.

10. The water electrolysis apparatus of claim 1 wherein the hydrogen and oxygen gradient separators are operated at a pressure of 1 to 30barA.