Method and device for improving running safety of electrolyzed water

Abstract

The invention discloses a method and a device for improving running safety of electrolyzed water. The device comprises an oxygen-liquid separator, a PEM electrolytic bath, a direct-current power supply, a hydrogen-liquid separator, a liquid discharge electromagnetic valve, a cooler and a degassing component, a cathode product outlet of the PEM electrolytic cell is connected with the hydrogen-liquid separator, a bottom outlet of the hydrogen-liquid separator is sequentially connected with the liquid discharge electromagnetic valve, the cooler and the degassing component, and the degassing component is sequentially connected with the oxygen-liquid separator, the circulating pump and the PEM electrolytic cell; an anode product outlet of the PEM electrolytic bath is connected with an oxygen-liquid separator, and a hydrogen-in-oxygen concentration sensor is arranged in the oxygen-liquid separator. The electrolyte is cooled, the gas contained in the electrolyte is discharged in combination with the vacuum degassing tank, and the content of the gas in the electrolyte is reduced, so that during recycling, the hydrogen concentration in oxygen is reduced, the operation safety is improved, and the system operation power range is widened.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen energy, and specifically relates to a method and a device for improving the safety of water electrolysis operation. Background Art

[0002] There are three sources of hydrogen energy: gray hydrogen, blue hydrogen, and green hydrogen, and green hydrogen is in line with current energy conservation and emission reduction. There are currently two main ways to prepare green hydrogen: alkaline water electrolysis and proton exchange membrane water electrolysis. In these two methods, due to the inherent characteristics of the diaphragm and the proton exchange membrane, hydrogen will penetrate the diaphragm from the cathode side and reach the anode side, and hydrogen and oxygen will dissolve in the electrolyte, and this phenomenon will become more obvious as the power decreases. This causes the concentration of hydrogen in oxygen to rise when the electrolyte is mixed and recycled, thereby limiting the lower limit of the power of the water electrolysis system for safe operation.

[0003] The existing technical solution is to separate the gas and the electrolyte through a steam-water separation device. This method can effectively separate the gas and the electrolyte, but it cannot remove the dissolved gas in the electrolyte, resulting in an increase in the concentration of hydrogen in the oxygen during the circulation process. In order to ensure the safety of the system operation, the lower limit of the operating power of the electrolytic water system is relatively high, especially in the alkaline electrolytic water system, the lower limit of the system operation is 30%. This makes it impossible for the electrolytic water system to match its volatility well when using wind and solar power, and its response speed is reduced, resulting in energy waste. Therefore, the current technical solution needs to limit the lower limit of the system operating power so that the concentration of hydrogen in oxygen is controlled within a certain range, usually not more than 2%, so as to ensure safety, but it sacrifices the matching of wind and solar power. Summary of the invention

[0005] The present invention mainly aims at the problem that dissolved gas in electrolyte is difficult to separate. By cooling the electrolyte and combining with a vacuum degassing tank to discharge the gas contained in the electrolyte, the gas content in the electrolyte is reduced, thereby reducing the hydrogen concentration in oxygen during recycling and reuse, improving operational safety, and increasing the system operating power range.

[0006] The technical solution of the present invention is as follows.

[0007] A device for improving the safety of water electrolysis operation comprises an oxygen-liquid separator, a PEM electrolyzer, a direct current power supply, a hydrogen-liquid separator, a liquid discharge solenoid valve, a cooler and a degassing component; the cathode product outlet of the PEM electrolyzer is connected to the hydrogen-liquid separator, the bottom outlet of the hydrogen-liquid separator is connected to the liquid discharge solenoid valve, the cooler and the degassing component in sequence, the degassing component is connected to the oxygen-liquid separator, a circulation pump and the PEM electrolyzer in sequence; the anode product outlet of the PEM electrolyzer is connected to the oxygen-liquid separator, and a hydrogen concentration sensor in oxygen is arranged inside the oxygen-liquid separator.

[0008] In the above device, the upper hydrogen outlet of the hydrogen-liquid separator is connected to the lower gas inlet of the hydrogen condenser, the hydrogen outlet in the hydrogen condenser is connected to the hydrogen discharge port, and the lower condensed water outlet is circulated to the hydrogen-liquid separator.

[0009] In the above device, the degassing component is also connected to the hydrogen exhaust port through a vacuum pump.

[0010] In the above device, the degassing component includes a first three-way valve, a first vacuum degassing tank, a second vacuum degassing tank, a second three-way valve and a third three-way valve; the first three-way valve is connected to the cooler, and the other two outlets are respectively connected to the first vacuum degassing tank and the second vacuum degassing tank, the first vacuum degassing tank and the second vacuum degassing tank are respectively connected to the third three-way valve; the third three-way valve is also connected to the oxygen-liquid separator.

[0011] In the above device, the upper gas outlets of the first vacuum degassing tank and the second vacuum degassing tank are respectively connected to the second three-way valve, and the second three-way valve is also connected to the hydrogen exhaust port through a vacuum pump.

[0012] A method for improving the safety of water electrolysis operation, wherein the cathode product of a PEM electrolyzer is a mixture of hydrogen and electrolyte, which is then initially separated by a hydrogen-liquid separator, and the gas is further purified and dried for storage; the liquid level of the electrolyte in the hydrogen-liquid separator is displayed by a liquid level gauge, and the liquid in the hydrogen-liquid separator is discharged by linkage control of an electromagnetic valve; a cooler is arranged after the electromagnetic valve to reduce the temperature of the discharged electrolyte, and the reduction in temperature is conducive to reducing the amount of gas dissolved in the electrolyte; the electrolyte is further introduced into a vacuum degassing tank, and the vacuum degassing tank is set to two identical branches to ensure that the electrolyte in the hydrogen-liquid separator is discharged smoothly, and a vacuum pump is used to pump it to a negative pressure and retain it for a period of time. The retention time is determined by the generation rate of the liquid in the gas-liquid separator and the volume of the vacuum degassing tank, so as to promote the discharge of hydrogen dissolved in the electrolyte, and the electrolyte after gas removal is discharged to the water inlet pipeline through the electromagnetic valve for recycling. The water outlet at the bottom of the oxygen-liquid separator in the water inlet pipeline is connected to the water inlet of the circulation pump, and the water outlet of the circulation pump is connected to the water inlet of the PEM electrolyzer. The schematic diagram is as attached Figure 1 shown.

[0013] Control strategy: According to the concentration value of hydrogen in oxygen, determine whether to remove hydrogen from the electrolyte through the vacuum degassing tank.

[0014] First, start the electrolytic water system to determine whether the hydrogen concentration in oxygen is greater than the first value: if it is less than the first value, it will operate normally and no operation will be performed; if it is greater than or equal to the first value, the vacuum degassing tank will be started. After the vacuum degassing tank is started, monitor the change in the hydrogen concentration in oxygen to determine whether the hydrogen concentration in oxygen is less than the second value: if it is less than the second value, the vacuum degassing tank will be stopped; if it is greater than or equal to the second value, the vacuum degassing tank will be kept running, and the judgment will be made in sequence. The logic diagram is as follows Figure 2 shown.

[0015] Specifically: first start the water electrolysis system to determine whether the hydrogen concentration in oxygen in the oxygen-liquid separator is greater than a first value: if it is less than the first value, the entire system operates normally, no operation is performed, and the first three-way valve, the second three-way valve and the third three-way valve are kept open, and the opening direction ensures that the liquid can flow from the first three-way valve through the vacuum degassing tank 1, and then flow to the third three-way valve to return to the oxygen-liquid separation tank. At this time, the second three-way valve keeps the vacuum degassing tank 1 closed; or ensures that the liquid can flow from the first three-way valve through the vacuum degassing tank 2 and then flow to the third three-way valve to return to the oxygen-liquid separation tank. The opening direction of the three-way valve is opposite to the above; at this time, the vacuum degassing tank does not work, and the water circulation is normal; if it is greater than or equal to the first value, the vacuum degassing tank is started, the first vacuum degassing tank 1 performs degassing operation, and the second vacuum degassing tank Tank 2 performs drainage and water storage operations, and the opening direction of the three-way valve ensures that the liquid can flow from the first three-way valve to the vacuum degassing tank 2, and then flow to the third three-way valve to return to the oxygen-liquid separation tank. At this time, the second three-way valve keeps the vacuum degassing tank 1 open; after the degassing is completed, the opening directions of the first three-way valve, the second three-way valve and the third three-way valve are switched at the same time, the second vacuum degassing tank 2 performs the degassing operation, and the first vacuum degassing tank 1 performs the drainage and water storage operations. After the vacuum degassing tank is started, the change of the hydrogen concentration in oxygen is monitored to determine whether the hydrogen concentration in oxygen is less than the second value: if it is less than the second value, the degassing operation of the vacuum degassing tank is stopped, and the opening states of the first three-way valve, the second three-way valve and the third three-way valve are kept unchanged, the vacuum gas storage tank does not work, and the water circulation is carried out normally; if it is greater than or equal to the second value, the vacuum degassing tank is kept running, and the judgment is made in turn; The first value is 1.8%-2.0%, preferably 1.8%; the second value is 0.8%-1.2%, preferably 1.0%.

[0016] Compared with the prior art, the advantages of the present invention are: 1. Using the value of hydrogen in oxygen as a judgment can more accurately determine the operation of the vacuum degassing tank. In the actual electrolysis process, the concentration of hydrogen in oxygen is usually higher in the low power section. This is because the amount of gas produced is small, while the amount of hydrogen dissolved in the electrolyte is certain, resulting in a high concentration of hydrogen in oxygen. As the power increases, the amount of gas produced is larger, which reduces the proportion of hydrogen in oxygen. Therefore, by judging in this way, the number of startup operations of the vacuum degassing tank can be reduced to meet the requirements, while reducing costs and simplifying the process. At the same time, reducing the lower limit of the operating power of the electrolysis system can better match the variability of wind and solar power.

[0017] 2. During the operation of the vacuum degassing tank, in order to ensure the continuous operation of the gas-liquid separator and the entire electrolytic reaction, a two-branch method is adopted. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the water electrolysis system and the vacuum degassing system; Figure 2 This is a diagram of the vacuum degassing control method.

[0019] The components in the figure are as follows: Oxygen-liquid separator 1, oxygen hydrogen concentration sensor 2, PEM electrolyzer 3, DC power supply 4, hydrogen-liquid separator 5, hydrogen condenser 6, drain solenoid valve 7, cooler 8, first three-way valve 9, first vacuum degassing tank 10, second vacuum degassing tank 11, second three-way valve 12, vacuum pump 13, third three-way valve 14, circulation pump 15. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] Example 1 This embodiment provides a device for improving the safety of water electrolysis operation. Figure 1As shown, it includes an oxygen-liquid separator 1, a PEM electrolyzer 3, a DC power supply 4, a hydrogen-liquid separator 5, a liquid discharge solenoid valve 7, a cooler 8 and a degassing component; the cathode product outlet of the PEM electrolyzer 3 is connected to the hydrogen-liquid separator 5, the bottom outlet of the hydrogen-liquid separator 5 is connected to the liquid solenoid valve 7, the cooler 8, and the degassing component in sequence, and the degassing component is connected to the oxygen-liquid separator 1, the circulation pump 15, and the PEM electrolyzer 3 in sequence; the anode product outlet of the PEM electrolyzer 3 is connected to the oxygen-liquid separator 1, and the oxygen-liquid separator 1 is provided with a hydrogen concentration sensor 2 in oxygen. The upper hydrogen outlet of the hydrogen-liquid separator 5 is connected to the lower gas inlet of the hydrogen condenser 6, the hydrogen outlet in the hydrogen condenser 6 is connected to the hydrogen discharge port, and the lower condensed water outlet is circulated to the hydrogen-liquid separator 5. The degassing component is also connected to the hydrogen discharge port through a vacuum pump 13. The degassing component includes a first three-way valve 9, a first vacuum degassing tank 10, a second vacuum degassing tank 11, a second three-way valve 12 and a third three-way valve 14; the first three-way valve 9 is connected to the cooler 8, and the other two outlets are connected to the first vacuum degassing tank 10 and the second vacuum degassing tank 11 respectively, and the first vacuum degassing tank 10 and the second vacuum degassing tank 11 are connected to the third three-way valve 14 respectively; the third three-way valve 14 is also connected to the oxygen-liquid separator 1. The upper gas outlets of the first vacuum degassing tank 10 and the second vacuum degassing tank 11 are respectively connected to the second three-way valve 12, and the second three-way valve 12 is also connected to the hydrogen exhaust port through the vacuum pump 13.

[0022] The following examples are carried out using the device in this example.

[0023] Example 2 A method for improving the safety of water electrolysis operation. In this embodiment, based on the concentration value of hydrogen in oxygen, it is determined whether to remove hydrogen from the electrolyte through a vacuum degassing tank.

[0024] First, start the water electrolysis system to determine whether the concentration of hydrogen in oxygen in the oxygen-liquid separator 1 is greater than the first value 1.8%: if it is less than the first value 1.8%, the entire system operates normally, no operation is performed, and the first three-way valve 9, the second three-way valve 12 and the third three-way valve 14 are kept open, and the opening direction ensures that the liquid can flow from the first three-way valve 9 through the first vacuum degassing tank 10, and then flow to the third three-way valve 14 and return to the oxygen-liquid separation tank 1. At this time, the second three-way valve 12 keeps the vacuum degassing tank 10 direction is closed; the vacuum gas storage tank does not work and the water circulation is carried out normally; if it is greater than or equal to the first value 1.8%, the vacuum degassing tank is started, the first vacuum degassing tank 10 performs the degassing operation, and the second vacuum degassing tank 11 performs the drainage and water storage operation. The three-way valve is opened in the direction to ensure that the liquid can flow from the first three-way valve 9 to the second vacuum degassing tank 11, and then flow to the third three-way valve 14 to return to the oxygen-liquid separation tank 1. At this time, the second three-way valve 12 keeps the second vacuum degassing tank 10 open; after the degassing is completed, the first three-way valve 9, the second three-way valve 12 and the third The three-way valve 14 is opened in the direction in which the second vacuum degassing tank 11 performs degassing operation, and the first vacuum degassing tank 10 performs drainage and water storage operation. After the vacuum degassing tank is started, the change of hydrogen concentration in oxygen is monitored to determine whether the hydrogen concentration in oxygen is less than the second value 1.0%: if it is less than the second value 1.0%, the degassing operation of the vacuum degassing tank is stopped, and the first three-way valve 9, the second three-way valve 12 and the third three-way valve 14 are kept in the open state unchanged, the vacuum gas storage tank does not work, and the water circulation is carried out normally; if it is greater than or equal to the second value 1.0%, the vacuum degassing tank is kept running and judged in sequence.

[0025] Example 3 A method for improving the safety of water electrolysis operation. In this embodiment, based on the concentration value of hydrogen in oxygen, it is determined whether to remove hydrogen from the electrolyte through a vacuum degassing tank.

[0026] First, start the water electrolysis system to determine whether the concentration of hydrogen in oxygen in the oxygen-liquid separator 1 is greater than the first value 2.0%: if it is less than the first value 2.0%, the entire system operates normally, no operation is performed, and the first three-way valve 9, the second three-way valve 12 and the third three-way valve 14 are kept open, and the opening direction ensures that the liquid can flow from the first three-way valve 9 through the vacuum degassing tank 11 and then flow to the third three-way valve 14 to return to the oxygen-liquid separation tank 1. At this time, the second three-way valve 12 keeps the vacuum degassing tank 11 closed; at this time, the vacuum gas storage tank does not work, and the water circulation is normal; if it is greater than or equal to the first value 2.0%, start the vacuum degassing tank, the first vacuum degassing tank 10 performs drainage and water storage degassing operations, the second vacuum degassing tank 11 performs degassing operations, and the three-way valve opening direction ensures that the liquid can flow from the first three-way valve 9 to the vacuum degassing tank 10, and then flow to the third three-way valve 14 to return to the oxygen-liquid separation tank 1. At this time, the second three-way valve 12 keeps the second vacuum degassing tank 11 closed. direction; after degassing is completed, the opening directions of the first three-way valve 9, the second three-way valve 12 and the third three-way valve 14 are switched at the same time, the second vacuum degassing tank 10 performs degassing operation, and the first vacuum degassing tank 11 performs drainage and water storage operations. After the vacuum degassing tank is started, the change of hydrogen concentration in oxygen is monitored to determine whether the hydrogen concentration in oxygen is less than the second value of 1.2%: if it is less than the second value of 1.2%, the degassing operation of the vacuum degassing tank is stopped, and the opening state of the first three-way valve 9, the second three-way valve 12 and the third three-way valve 14 remains unchanged, the vacuum gas storage tank does not work, and the water circulation is carried out normally; if it is greater than or equal to the second value of 1.2%, the vacuum degassing tank is kept running and judged in turn.

[0027] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for improving the safety of water electrolysis operation, characterized in that: The invention comprises an oxygen-liquid separator (1), a PEM electrolyzer (3), a direct current power supply (4), a hydrogen-liquid separator (5), a liquid discharge electromagnetic valve (7), a cooler (8) and a degassing component; the cathode product outlet of the PEM electrolyzer (3) is connected to the hydrogen-liquid separator (5), the bottom outlet of the hydrogen-liquid separator (5) is connected to the liquid discharge electromagnetic valve (7), the cooler (8) and the degassing component in sequence, and the degassing component is connected to the oxygen-liquid separator (1), a circulation pump (15) and the PEM electrolyzer (3) in sequence; the anode product outlet of the PEM electrolyzer (3) is connected to the oxygen-liquid separator (1), and a hydrogen concentration sensor (2) is arranged inside the oxygen-liquid separator (1).

2. A device for improving the safety of water electrolysis operation as claimed in claim 1, characterized in that: The upper hydrogen outlet of the hydrogen-liquid separator (5) is connected to the lower gas inlet of the hydrogen condenser (6), the hydrogen outlet in the hydrogen condenser (6) is connected to the hydrogen discharge port, and the lower condensed water outlet is circulated to the hydrogen-liquid separator (5).

3. A device for improving the safety of water electrolysis operation as claimed in claim 1, characterized in that: The degassing component is also connected to the hydrogen exhaust port via a vacuum pump (13).

4. A device for improving the safety of water electrolysis operation as claimed in claim 1, characterized in that: The degassing component comprises a first three-way valve (9), a first vacuum degassing tank (10), a second vacuum degassing tank (11), a second three-way valve (12) and a third three-way valve (14); the first three-way valve (9) is connected to a cooler (8), and the other two outlets are respectively connected to the first vacuum degassing tank (10) and the second vacuum degassing tank (11); the first vacuum degassing tank (10) and the second vacuum degassing tank (11) are respectively connected to the third three-way valve (14); and the third three-way valve (14) is also connected to an oxygen-liquid separator (1).

5. A device for improving the safety of water electrolysis operation as claimed in claim 4, characterized in that: The upper gas outlets of the first vacuum degassing tank (10) and the second vacuum degassing tank (11) are respectively connected to a second three-way valve (12), and the second three-way valve (12) is also connected to a hydrogen exhaust port via a vacuum pump (13).

6. A method for improving the safety of water electrolysis operation using the device according to any one of claims 1 to 5, characterized in that: The steps include: The cathode product of the PEM electrolyzer is a mixture of hydrogen and electrolyte, which is then initially separated by a hydrogen-liquid separator, and the gas will be further purified and dried for storage; the liquid level of the electrolyte in the hydrogen-liquid separator is displayed by a liquid level gauge, and the liquid in the hydrogen-liquid separator is discharged through the linkage control of the solenoid valve; a cooler is configured after the solenoid valve to reduce the temperature of the discharged electrolyte, and the reduction in temperature is conducive to reducing the amount of gas dissolved in the electrolyte; the electrolyte is further introduced into a vacuum degassing tank, and the vacuum degassing tank is set to two identical branches to ensure that the electrolyte in the hydrogen-liquid separator is discharged smoothly, and a vacuum pump is used to pump it to negative pressure and retain it for a period of time. The retention time is determined by the generation rate of liquid in the gas-liquid separator and the volume of the vacuum degassing tank, which promotes the discharge of hydrogen dissolved in the electrolyte, and the electrolyte after gas removal is discharged to the water inlet pipeline through the solenoid valve for recycling.

7. A method for improving the safety of water electrolysis operation as claimed in claim 6, characterized in that: The water outlet at the bottom of the oxygen-liquid separator in the water inlet pipeline is connected to the water inlet of the circulation pump, and the water outlet of the circulation pump is connected to the water inlet of the PEM electrolyzer.

8. A method for improving the safety of water electrolysis operation as claimed in claim 6, characterized in that: According to the concentration value of hydrogen in oxygen, it is determined whether the hydrogen in the electrolyte should be removed through the vacuum degassing tank.

9. A method for improving the safety of water electrolysis operation as claimed in claim 8, characterized in that: First, start the electrolytic water system to determine whether the hydrogen concentration in oxygen is greater than a first value: if it is less than the first value, operate normally without any operation; if it is greater than or equal to the first value, start the vacuum degassing tank; after the vacuum degassing tank is started, monitor the change in the hydrogen concentration in oxygen to determine whether the hydrogen concentration in oxygen is less than a second value: if it is less than the second value, stop the vacuum degassing tank; if it is greater than or equal to the second value, keep the vacuum degassing tank running, and make the following judgments in sequence.

10. A method for improving the safety of water electrolysis operation as claimed in claim 9, characterized in that: Specifically: First, the water electrolysis system is started to operate, and it is determined whether the concentration of hydrogen in oxygen in the oxygen-liquid separator (1) is greater than a first value. If it is less than the first value, the entire system operates normally, and no operation is performed. The first three-way valve (9), the second three-way valve (12) and the third three-way valve (14) are kept open, and the opening direction ensures that the liquid can flow from the first three-way valve (9) through the vacuum degassing tank (10), and then flow to the third three-way valve (14) to return to the oxygen-liquid separation tank (1). At this time, the second three-way valve (12) keeps the first vacuum degassing tank (10) closed; or ensures that the liquid can flow from the first three-way valve (9) through the vacuum degassing tank (11) and then flow to the third three-way valve (14) to return to the oxygen-liquid separation tank (1). The opening direction of the three-way valve is opposite to the above. At this time, the vacuum gas storage tank does not work, and the water circulation is carried out normally. If it is greater than or equal to the first value, the vacuum degassing tank is started to operate, the first vacuum degassing tank (10) performs a degassing operation, and the second vacuum degassing tank (11) draining and storing water, the three-way valve is opened in a direction that ensures that the liquid can flow from the first three-way valve (9) to the vacuum degassing tank (11), and then to the third three-way valve (14) to return to the oxygen-liquid separation tank (1), at which time the second three-way valve (12) keeps the vacuum degassing tank (10) open; after the degassing is completed, the opening directions of the first three-way valve (9), the second three-way valve (12) and the third three-way valve (14) are switched at the same time, the second vacuum degassing tank (11) performs the degassing operation, and the first vacuum degassing tank (10) performs the draining and storing water operation. After the vacuum degassing tank is started, the change of the hydrogen concentration in oxygen is monitored to determine whether the hydrogen concentration in oxygen is less than a second value: if it is less than the second value, the degassing operation of the vacuum degassing tank is stopped, the first three-way valve (9), the second three-way valve (12) and the third three-way valve (14) are kept open, the vacuum gas storage tank does not work, and the water circulation is carried out normally; if it is greater than or equal to the second value, the vacuum degassing tank is kept running, and the judgment is made in sequence; The first value is 1.8%-2.0%; the second value is 0.8%-1.2%.

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