Oxygen gas-liquid separation device for reducing hydrogen content in oxygen, water electrolysis hydrogen production system and operation method of water electrolysis hydrogen production system

Abstract

The invention provides an oxygen gas-liquid separation device for reducing the content of hydrogen in oxygen in a water electrolysis hydrogen production system, the water electrolysis hydrogen production system and an operation method of the water electrolysis hydrogen production system. The deep separation device for hydrogen in oxygen comprises an oxygen purification catalytic reactor and an aeration device; a first exhaust port and a second exhaust port are formed in the left side and the right side of the top of the oxygen gas-liquid separator respectively; the aeration device is arranged in the oxygen gas-liquid separator and below the liquid level; a crude oxygen inlet and a purified oxygen outlet are formed in the two ends of the oxygen purification catalytic reactor respectively, the crude oxygen inlet is connected to the first exhaust port, the purified oxygen outlet is connected to the air inlet end of the aeration device, and the oxygen purification catalytic reactor adopts a catalyst to enable H2 and O2 to react rapidly to generate H2O. According to the invention, the concentration of hydrogen in oxygen can be greatly reduced, and safe and stable operation of the water electrolysis hydrogen production system under low load is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by water electrolysis, and in particular, relates to an oxygen gas-liquid separation device for reducing the hydrogen content in oxygen, a water electrolysis hydrogen production system and an operation method thereof. Background Art

[0002] Hydrogen production by water electrolysis converts renewable energy such as photovoltaics and wind power into green hydrogen energy, which is applied to chemical, metallurgical, transportation and other fields to achieve deep decarbonization. It is an important support for my country's "carbon neutrality" strategic goal. However, the problem of gas purity in the water electrolysis process has always been an important factor restricting the efficiency of the system. The concentration of hydrogen in oxygen (HTO) is a key factor in determining the load limit of water electrolysis, and high HTO levels pose a risk of explosion. Generally, when the concentration of hydrogen in oxygen exceeds 2%, the electrolysis system will be forced to shut down and the hydrogen production process will stop. Reducing the concentration of hydrogen in oxygen in the electrolysis system can not only minimize safety issues, but also improve electrolysis efficiency.

[0003] Therefore, in order to solve the operational safety problem caused by the increase of hydrogen concentration in oxygen under low load in the water electrolysis hydrogen production system, it is necessary to design a suitable solution to reduce the hydrogen impurity content in the oxygen separator. This measure not only helps to improve the safety of the system, but also further optimizes the electrolysis efficiency and promotes the large-scale development of the green hydrogen energy industry.

[0004] CN115140712A discloses an alkaline water electrolysis hydrogen production system and its oxygen impurity removal protection device and protection method. An oxygen gas-liquid separator is connected to an oxygen purification device to purify and remove impurities from the crude oxygen in the separator. The purified oxygen is stored in the oxygen storage device. When the water electrolysis hydrogen production system is in low-load operation, the stored oxygen is passed into the oxygen separator to reduce the hydrogen impurity content in the oxygen in the oxygen separator. This method reduces the hydrogen content in the oxygen by increasing the oxygen content, but the system introduces complex gas purification and gas storage equipment, which greatly increases the footprint of the electrolysis system and does not meet the development needs of industrial container compactness.

[0005] Therefore, in order to address the problem of excessively high hydrogen content in oxygen in industrial electrolysis systems operating at low loads, it is necessary to develop more efficient, more feasible, and integrated technical devices for reducing the concentration of hydrogen in oxygen to ensure the safe operation of the electrolysis system under low loads. This is of great significance for promoting the safe, stable and efficient development of the water electrolysis industry. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides an oxygen gas-liquid separation device for reducing the hydrogen content in oxygen in a water electrolysis hydrogen production system, a water electrolysis hydrogen production system and an operation method thereof. Not only can the hydrogen content in oxygen and the separation load of the gas-liquid separator of the water electrolysis hydrogen production system be reduced, ensuring that the water electrolysis hydrogen production system can operate safely and stably at low loads; it can even be directly coupled inside the gas-liquid separator, meeting the intensive and compact industrial development needs of the electrolysis system.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] An oxygen gas-liquid separation device for reducing the hydrogen content in oxygen in a hydrogen production system by electrolysis of water, comprising an oxygen gas-liquid separator and an oxygen-hydrogen deep separation device, wherein the oxygen-hydrogen deep separation device comprises an oxygen purification catalytic reactor and an aeration device; the oxygen gas-liquid separator is provided with a first exhaust port and a second exhaust port on the left and right sides of the top along the liquid flow direction, respectively, and the aeration device is arranged inside the oxygen gas-liquid separator near the second exhaust port and below the liquid surface of the electrolyte;

[0009] A crude oxygen inlet and a purified oxygen outlet are respectively provided at both ends of the oxygen purification catalytic reactor, the crude oxygen inlet is connected to the first exhaust port, and the purified oxygen outlet is connected to the air inlet end of the aeration device. The oxygen purification catalytic reactor uses a catalyst to rapidly react H2 and O2 to generate H2O.

[0010] The present invention is further configured such that the oxygen purification catalytic reactor is arranged outside the oxygen gas-liquid separator.

[0011] The present invention is further configured such that the oxygen purification catalytic reactor is arranged inside the oxygen gas-liquid separator and below the liquid surface of the electrolyte.

[0012] The present invention is further configured such that a power device is installed on the connecting pipe between the first exhaust port and the oxygen purification catalytic reactor, for transporting the crude oxygen in the oxygen gas-liquid separator to the oxygen purification catalytic reactor. The power device is preferably a fan.

[0013] The present invention is further configured such that a demister is installed on the connecting pipe between the crude oxygen outlet and the blower. The demister is used to remove trace liquid mixed in the gas.

[0014] The present invention is further configured such that a hydrogen sensor is installed on the connecting pipe between the gas inlet end and the gas outlet of the oxygen purification catalytic reactor, and a hydrogen sensor is installed at the outlet of the purified oxygen to monitor the hydrogen content in oxygen.

[0015] The present invention is further configured such that the catalyst in the oxygen purification catalytic reactor is selected from one or more of a palladium catalyst, a platinum-based catalyst, and a silver-based catalyst.

[0016] The present invention also provides a water electrolysis hydrogen production system, comprising an electrolyzer, an oxygen gas-liquid separation device and a hydrogen gas-liquid separation device respectively connected to the electrolyzer, wherein the oxygen gas-liquid separation device adopts the oxygen gas-liquid separation device described above.

[0017] The present invention also provides an operation method of the water electrolysis hydrogen production system, wherein the oxygen-hydrogen deep separation device is turned on and operated when the water electrolysis hydrogen production system is operated at a low load or the hydrogen content in oxygen in the oxygen gas-liquid separator is relatively high; and is turned off and operated when the water electrolysis hydrogen production system is operated at a high load or the hydrogen content in oxygen in the oxygen gas-liquid separator is relatively low.

[0018] The present invention is further configured to control the oxygen space velocity at the inlet of the oxygen purification catalytic reactor to be ≥5h -1 Preferably, the air velocity is 5 to 15 h -1 , more preferably 7.5 to 10 hours -1 .

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention provides an oxygen gas-liquid separation device for reducing the hydrogen content in oxygen in a water electrolysis hydrogen production system. The oxygen-hydrogen deep separation device can be fully coupled and installed in an oxygen gas-liquid separator, which can not only reduce the hydrogen content in oxygen in the water electrolysis hydrogen production system, ensure the safe and stable operation of the water electrolysis hydrogen production system at low load, but also meet the intensive and compact industrial development needs of the electrolysis system.

[0021] (2) The oxygen gas-liquid separation device provided by the present invention first utilizes hydrogen and oxygen to react under the action of a catalyst to generate water to remove trace hydrogen, and at the same time utilizes the waste heat generated to exchange heat with the electrolyte and blow off with an aeration device, which can greatly reduce the concentration of hydrogen in oxygen. The method is simple in principle and has a good hydrogen removal effect, and has a good prospect for application in industrial water electrolysis systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the process flow of the water electrolysis hydrogen production system described in Example 1.

[0023] Figure 2 This is a schematic diagram of the working process of coupling the oxygen gas-liquid separator and the oxygen-hydrogen deep separation device in Example 1.

[0024] Figure 3 This is a schematic structural diagram of the oxygen purification catalytic reactor;

[0025] Figure 4This is a schematic diagram of the process flow of the water electrolysis hydrogen production system in Example 10.

[0026] Figure 5 This is a schematic diagram of the working process of coupling the oxygen gas-liquid separator with the oxygen-hydrogen deep separation device in Example 10.

[0027] Figure 6 This is a schematic diagram of the coupling working process of the oxygen gas-liquid separator and the oxygen-hydrogen deep separation device in Comparative Example 3.

[0028] Figure 7 This is a schematic diagram of the coupling working process of the oxygen gas-liquid separator and the oxygen-hydrogen deep separation device in Comparative Example 8.

[0029] Among them, 1. electrolytic cell, 1-1. liquid inlet, 2. oxygen gas-liquid separator, 2-1. first exhaust port, 2-2. second exhaust port, 3. hydrogen gas-liquid separator, 4. oxygen purification catalytic reactor, 4-1. crude oxygen inlet, 4-2. purified oxygen outlet, 5. aeration plate, 6. fan, 7. hydrogen sensor, 8. demister. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention is clearly and completely described below with specific embodiments. It should be understood that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention. Unless otherwise defined, all professional and scientific terms used in the text have the same meanings as those familiar to those skilled in the art.

[0031] In order to reduce the hydrogen content in oxygen in a water electrolysis hydrogen production system and improve the safety of the water electrolysis hydrogen production system, the present invention provides an oxygen gas-liquid separation device for reducing the hydrogen content in oxygen in the water electrolysis hydrogen production system, the oxygen gas-liquid separation device comprises an oxygen gas-liquid separator and an oxygen-hydrogen deep separation device, the oxygen-hydrogen deep separation device comprises an oxygen purification catalytic reactor and an aeration device;

[0032] The oxygen gas-liquid separator is provided with a first exhaust port and a second exhaust port at the top of the left and right sides along the liquid flow direction, respectively; the aeration device is arranged inside the oxygen gas-liquid separator near the second exhaust port and below the liquid surface of the electrolyte;

[0033] The oxygen purification catalytic reactor is provided with a crude oxygen inlet and a purified oxygen outlet at the left and right ends along the gas transport direction, respectively. The crude oxygen inlet is connected to the first exhaust port, and the purified oxygen outlet is connected to the air inlet end of the aeration device. The oxygen purification catalytic reactor uses a catalyst to rapidly react H2 and O2 to generate H2O.

[0034] In the present invention, each connecting pipeline of the oxygen gas-liquid separation device is installed with a control valve.

[0035] In one embodiment of the present invention, a power device is installed on the connecting pipe between the crude oxygen outlet and the oxygen purification catalytic reactor; the power device is preferably a fan.

[0036] In one embodiment of the present invention, the oxygen purification catalytic reactor is arranged outside the oxygen gas-liquid separator.

[0037] In one embodiment of the present invention, the oxygen purification catalytic reactor is disposed inside the oxygen gas-liquid separator and below the liquid level of the electrolyte.

[0038] In one embodiment of the present invention, a demister is installed on the connecting pipe between the crude oxygen outlet and the blower near the crude oxygen outlet.

[0039] In one embodiment of the present invention, a hydrogen sensor is installed on the connecting pipe between the gas inlet end and the gas outlet of the oxygen purification catalytic reactor, and a hydrogen sensor is installed at the outlet of the purified oxygen.

[0040] In one embodiment of the present invention, the catalyst in the oxygen purification catalytic reactor is selected from one of HX-palladium catalyst, platinum catalyst and silver catalyst.

[0041] The present invention provides a water electrolysis hydrogen production system, comprising an electrolyzer, an oxygen gas-liquid separation device and a hydrogen gas-liquid separation device respectively connected to the electrolyzer, wherein the oxygen gas-liquid separation device adopts any one of the oxygen gas-liquid separation devices described above; the electrolyte separated by the oxygen gas-liquid separation device and the hydrogen gas-liquid separation device is transported back to the electrolyzer.

[0042] In the present invention, each connecting pipeline in the water electrolysis hydrogen production system is provided with a control valve.

[0043] The present invention also provides an operation method of the water electrolysis hydrogen production system, wherein the oxygen-hydrogen deep separation device in the oxygen gas-liquid separation device is turned on and operated when the water electrolysis hydrogen production system is running at a low load or the concentration of hydrogen in oxygen in the oxygen gas-liquid separator is high; and is turned off and operated when the water electrolysis hydrogen production system is running at a high load or the concentration of hydrogen in the oxygen gas-liquid separator is low. In this field, the low-load operation generally refers to the current density of the system operation being less than 30% of the rated current density; the high concentration of hydrogen in oxygen refers to the risk of the electrolyzer shutting down due to the excessive concentration of hydrogen in oxygen when the electrolyzer is running at a low load.

[0044] In one embodiment of the present invention, when the oxygen-hydrogen deep separation device is turned on, the oxygen space velocity at the inlet of the oxygen purification catalytic reactor is controlled to be ≥5h-1 ; preferably 5 to 15 hours -1 ; More preferably 7.5 to 10 hours -1 .

[0045] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0046] Example 1

[0047] like Figures 1 to 3 As shown, this embodiment provides a water electrolysis hydrogen production system, comprising an electrolyzer 1, an oxygen gas-liquid separator 2 and a hydrogen gas-liquid separator 3 respectively connected to the oxygen end and the hydrogen end of the electrolyzer 1, and an oxygen-hydrogen deep separation device provided on the oxygen gas-liquid separator 2;

[0048] The oxygen gas-liquid separator 2 and the hydrogen gas-liquid separator 3 are respectively provided with a gas-liquid mixture inlet and an electrolyte outlet at the left and right ends. The electrolyte outlets of the oxygen gas-liquid separator 2 and the hydrogen gas-liquid separator 3 are both connected to the liquid inlet 1-1 of the electrolytic cell 1 to return the separated electrolyte to the electrolytic cell 1; the first exhaust port 2-1 and the second exhaust port 2-2 are respectively provided at the left and right ends of the top of the oxygen gas-liquid separator 2;

[0049] The oxygen-hydrogen deep separation device comprises an oxygen purification catalytic reactor 4 and an aeration plate 5, which are sequentially arranged at the bottom of the inner side of the oxygen gas-liquid separator 2 along the liquid flow direction. A crude oxygen inlet 4-1 and a purified oxygen outlet 4-2 are respectively provided at both ends of the oxygen purification catalytic reactor 4, and a condensate outlet (not shown in the figure) is provided at the bottom. The oxygen inlet 4-1 is connected to the first exhaust port 2-1 by a pipeline, and a fan 6 is installed on the connecting pipeline between the crude oxygen inlet 4-1 and the first exhaust port 2-1, which is used to preferentially transport the gas in the oxygen gas-liquid separator 2 to the oxygen purification catalytic reactor 4, and the purified oxygen outlet 4-2 is connected to the air inlet end of the aeration plate 5 by a pipeline.

[0050] The oxygen containing a small amount of hydrogen enters the oxygen purification catalytic reactor 4 through the crude oxygen inlet 4-1, and under the action of the catalyst, H2 and O2 react to generate H2O, thereby removing a small amount of hydrogen in the oxygen; the purified oxygen is discharged through the purified oxygen outlet 4-2, and is transported to the aeration disk 5 through a pipeline for aeration, and finally discharged through the second exhaust port 2-2.

[0051] The connecting pipe between the blower 6 and the crude oxygen inlet 4-1 and the second exhaust port 2-2 are provided with a hydrogen sensor 7 for real-time detection of the hydrogen content in the gas. A demister 8 is also installed on the pipe near the first exhaust port 2-1 for pre-treatment of the gas entering the oxygen purification catalytic reactor 4.

[0052] In the water electrolysis hydrogen production system, each connecting pipeline is installed with a control valve.

[0053] In the embodiment of the present invention, the rated current density of the water electrolysis hydrogen production system is about 3000A / m 2 The catalyst in the oxygen purification catalytic reactor 4 uses aluminum oxide palladium catalyst particles, the main particle size range of which is 3-5 mm, and the amount of catalyst used in the reactor is 0.5 m 3 The electrolyte circulation flow rate is set to 5L / min, and the water electrolysis hydrogen production system is controlled to operate at a low load, with a current density of 300A / m 2 , control the oxygen space velocity at the inlet of oxygen purification catalytic reactor to 2.5h -1 The hydrogen content in the oxygen discharged from the second exhaust port 2-2 was measured using a gas chromatograph. The test result showed that the hydrogen content in the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator 2 was 1.87%.

[0054] Embodiments 2 to 5

[0055] The difference between Examples 2 to 5 and Example 1 is only the difference in controlling the oxygen space velocity. The oxygen space velocity and the hydrogen content in the oxygen discharged from the second exhaust port 2-2 of each example are shown in Table 1.

[0056] Table 1 Hydrogen content in oxygen at the outlet of oxygen gas-liquid separator

[0057]

[0058] Example 6

[0059] Compared with Example 1, the only difference is that the water electrolysis hydrogen production system is operated under high load, and the current density is 1000A / m 2 It was detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator was 0.73%.

[0060] Embodiments 7 to 10

[0061] The difference between Examples 7 to 10 and Example 6 is only the difference in controlling the oxygen space velocity. The oxygen space velocity of each example and the detected hydrogen content in the oxygen discharged from the second exhaust port 2-2 are shown in Table 2.

[0062] Table 2 Hydrogen content in oxygen at the outlet of oxygen gas-liquid separator

[0063]

[0064] Embodiment 11

[0065] refer to Figure 4 and Figure 5 This embodiment provides a water electrolysis hydrogen production system, which is different from the embodiment 2 in that the position of the oxygen purification reactor 4 is different. In this embodiment, the oxygen purification reactor 4 is arranged outside the oxygen gas-liquid separator 2. It is detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator is 1.87%.

[0066] Comparative Example 1

[0067] Compared with Example 1, the difference is that the oxygen gas-liquid separator is not equipped with an oxygen-hydrogen deep separation device. It is detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator is 1.95%.

[0068] Comparative Example 2

[0069] Compared with Example 7, the difference is that the oxygen gas-liquid separator is not equipped with an oxygen-hydrogen deep separation device. It is detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator is 0.78%.

[0070] According to the above results, it can be seen that the present invention can significantly reduce the hydrogen content in the hydrogen production system by coupling the oxygen-hydrogen deep separation device to the oxygen gas-liquid separator at a certain space velocity; after the oxygen-hydrogen deep separation device is installed, 300A / m 2 Under low load, the hydrogen content in oxygen can be reduced to a maximum of 1.55%, which is 18% lower than that without the installation of oxygen-hydrogen deep separation device.

[0071] Comparative Example 3

[0072] like Figure 6 As shown, compared with Example 1, the only difference is that the oxygen-hydrogen deep separation device does not have an aeration plate 5. It is detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator is 1.9%.

[0073] Comparative Examples 4 to 12

[0074] Compared with Comparative Example 3, the difference is that the oxygen space velocity is different. The specific current density and oxygen space velocity values ​​of each comparative example, as well as the detected hydrogen content in oxygen are shown in Table 3.

[0075] Table 3 Hydrogen content in oxygen at the outlet of oxygen gas-liquid separator

[0076]

[0077] Comparative Example 8

[0078] like Figure 7As shown, compared with Example 11, the only difference is that the oxygen-hydrogen deep separation device does not have an aeration plate 5. It is detected that the hydrogen content of the oxygen discharged from the second exhaust port 2-2 of the oxygen gas-liquid separator is 1.90%.

[0079] This application is described in detail for the purpose of enabling those skilled in the art to understand the contents of this application and implement them. This is not intended to limit the scope of protection of this application. Any equivalent changes or modifications made according to the spirit of this application should be included in the scope of protection of this application.

Claims

1. An oxygen gas-liquid separation device for reducing the hydrogen content in oxygen in a water electrolysis hydrogen production system, characterized in that: It includes an oxygen gas-liquid separator and an oxygen-hydrogen deep separation device, wherein the oxygen-hydrogen deep separation device includes an oxygen purification catalytic reactor and an aeration device; The oxygen gas-liquid separator is provided with a first exhaust port and a second exhaust port on the left and right sides of the top along the liquid flow direction, respectively; the aeration device is arranged inside the oxygen gas-liquid separator near the second exhaust port and below the liquid surface of the electrolyte; the two ends of the oxygen purification catalytic reactor are provided with a crude oxygen inlet and a purified oxygen outlet, respectively; the crude oxygen inlet is connected to the first exhaust port, and the purified oxygen outlet is connected to the air inlet end of the aeration device; the oxygen purification catalytic reactor uses a catalyst to rapidly react H2 and O2 to generate H2O.

2. The oxygen gas-liquid separation device according to claim 1, characterized in that: The oxygen purification catalytic reactor is arranged outside the oxygen gas-liquid separator.

3. The oxygen gas-liquid separation device according to claim 1, characterized in that: The oxygen purification catalytic reactor is arranged inside the oxygen gas-liquid separator and below the liquid level of the electrolyte.

4. The oxygen gas-liquid separation device according to claim 1, characterized in that: A power device is installed on the connecting pipeline between the first exhaust port and the oxygen purification catalytic reactor.

5. The oxygen gas-liquid separation device according to claim 1, characterized in that: A demister is installed on the connecting pipe between the crude oxygen outlet and the fan.

6. The oxygen gas-liquid separation device according to claim 1, characterized in that: A hydrogen sensor is installed on the connecting pipe between the gas inlet end and the gas outlet of the oxygen purification catalytic reactor, and a hydrogen sensor is installed at the outlet of the purified oxygen.

7. The oxygen gas-liquid separation device according to claim 1, characterized in that: The catalyst in the oxygen purification catalytic reactor is selected from one or more of a palladium-based catalyst, a platinum-based catalyst, and a silver-based catalyst.

8. A system for producing hydrogen by electrolysis of water, characterized in that: It comprises an electrolytic cell, an oxygen gas-liquid separation device and a hydrogen gas-liquid separation device respectively connected to the electrolytic cell, wherein the oxygen gas-liquid separation device adopts the oxygen gas-liquid separation device according to any one of claims 1 to 7.

9. An operating method of the water electrolysis hydrogen production system as claimed in claim 8, characterized in that: The oxygen-hydrogen deep separation device is turned on and operated when the water electrolysis hydrogen production system is running at a low load or the hydrogen content in oxygen in the oxygen gas-liquid separator is relatively high; and is turned off and operated when the water electrolysis hydrogen production system is running at a high load or the hydrogen content in oxygen in the oxygen gas-liquid separator is relatively low.

10. The operating method of the water electrolysis hydrogen production system according to claim 9, characterized in that: Control the oxygen space velocity at the inlet of the oxygen purification catalytic reactor to be ≥5h -1 .

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