Alkali-containing wastewater zero discharge device for hydrogen production through water electrolysis

Abstract

The utility model discloses an alkali-containing wastewater zero discharge device for water electrolysis hydrogen production, which comprises a hydrogen side water seal device, a hydrogen side degassing device, a waste alkali collecting tank, a waste alkali pump, an oxygen side water seal device and an oxygen side degassing device, and a hydrogen side liquid phase outlet pipeline of the hydrogen side degassing device goes down and extends into the waste alkali collecting tank; an oxygen side liquid phase outlet pipeline of the oxygen side degassing device descends downwards and extends into the waste alkali collecting tank; an emptying pipeline of the waste alkali collecting tank is communicated with the atmosphere, the waste alkali pump goes down a slope through an inlet pipeline and extends into the waste alkali collecting tank, and an outlet of the waste alkali pump is communicated with any one of the water supplementing tank, the alkali preparing tank or the alkali transporting tank car. On the premise that safety is guaranteed and investment and occupied space are saved, alkali-containing wastewater is recycled to serve as a raw material, zero emission of the alkali-containing wastewater is achieved, and meanwhile, by designing a centralized alkali-containing wastewater collecting system, the waste water is recycled, and the cost is reduced. The hydrogen-side alkali-containing wastewater and the oxygen-side alkali-containing wastewater enter a wastewater collection system after hydrogen and oxygen are removed through respective water seals and degassing devices, and explosive gas formed by mixing of hydrogen and oxygen is avoided.

Description

Technical Field

[0001] The utility model belongs to the field of water electrolysis hydrogen production, and in particular relates to a zero-discharge device for alkaline wastewater in water electrolysis hydrogen production. Background Art

[0002] At present, the field of hydrogen production by water electrolysis can be divided into four technologies according to the type of electrolyte: alkaline water electrolysis (AWE), proton exchange membrane (PEM) water electrolysis, solid oxide electrolysis (SOEC), and anion exchange membrane electrolysis (AEM). Among them, although the efficiency of proton exchange membrane (PEM) water electrolysis has been improved to 74-90%, due to the use of more expensive materials, the overall cost is relatively high, and it is currently only used on a small scale; solid oxide electrolysis (SOEC) and anion exchange membrane electrolysis (AEM) are still in the early stage of small-scale commercialization; and alkaline water electrolysis (AWE) technology is the most mature and is most widely used in the field of large-scale energy storage.

[0003] The electrolyte of the alkaline electrolytic cell is generally 30wt% KOH solution, and

[0004] ~0.2wt% V2O5 additive or potassium dichromate additive. Wastewater will be generated in the gas-liquid separation process (gas-liquid separation of alkaline hydrogen and oxygen-containing oxygen), hydrogen drying and purification process (dehydration and drying of crude hydrogen), and oxygen drying and purification process (dehydration and drying of crude oxygen) of water electrolysis hydrogen production. The alkali content in the total wastewater discharge is ~0.03%wt, and trace amounts of V2O5 or potassium dichromate additives seriously exceed the acceptance indicators of the sewage treatment plant, which often becomes the pain point of the water electrolysis hydrogen production wastewater discharge system and downstream sewage treatment and the focus of project environmental impact assessment. Utility Model Content

[0005] In order to solve the deficiencies in the above-mentioned technical problems, the utility model discloses a zero-discharge device for alkaline wastewater for hydrogen production by water electrolysis. Under the premise of ensuring safety and taking into account saving investment and land occupation, the alkaline wastewater is recycled and used as raw material to achieve zero discharge of alkaline wastewater. At the same time, by designing a centralized alkaline wastewater collection system, the alkaline wastewater on the hydrogen side and the oxygen side are respectively removed of hydrogen and oxygen through their respective water seals and degassing devices before entering the wastewater collection system, thereby avoiding the mixing of hydrogen and oxygen to form explosive gas.

[0006] The above technical objectives of the utility model are achieved through the following technical solutions:

[0007] A zero-discharge device for alkaline wastewater in water electrolysis hydrogen production includes a hydrogen side water seal device, a hydrogen side degassing device, a waste alkali collection tank, a waste alkali pump, an oxygen side water seal device, and an oxygen side degassing device, wherein:

[0008] The inlet end of the hydrogen side water seal device is respectively connected to the hydrogen side desalted water pipeline and the hydrogen side alkaline wastewater main pipe, the gas phase outlet of the hydrogen side water seal device is connected to the hydrogen side vent pipeline, the overflow port of the hydrogen side water seal device is connected to the hydrogen side degassing device through the hydrogen side overflow pipeline, and the hydrogen side liquid phase outlet pipeline of the hydrogen side degassing device is downhill and extends inward to the waste alkali collection tank;

[0009] The inlet end of the oxygen side water seal device is respectively connected to the oxygen side desalted water pipeline and the oxygen side alkaline wastewater main pipe, the gas phase outlet of the oxygen side water seal device is connected to the oxygen side vent pipeline, the overflow port of the oxygen side water seal device is connected to the oxygen side degassing device via the oxygen side overflow pipeline, and the oxygen side liquid phase outlet pipeline of the oxygen side degassing device is downhill and extends inward to the waste alkali collection tank;

[0010] The venting pipeline of the waste alkali collecting tank is connected to the atmosphere, the waste alkali pump extends downhill through the inlet pipeline and inwardly into the waste alkali collecting tank, and the outlet of the waste alkali pump is connected to any one of the water replenishment tank, the alkali preparation tank or the alkali transport tank truck.

[0011] Preferably, the alkaline wastewater on the hydrogen side flows downhill along the alkaline wastewater main pipe on the hydrogen side toward the water seal device on the hydrogen side.

[0012] Preferably, the alkaline wastewater on the oxygen side flows downhill along the alkaline wastewater main pipe on the oxygen side toward the water seal device on the oxygen side.

[0013] Preferably, a flame arrester is installed on the hydrogen side venting pipeline.

[0014] Preferably, the overflow port of the hydrogen side water seal device is directed downhill toward the hydrogen side degassing device through a hydrogen side overflow pipeline.

[0015] Preferably, the overflow port of the oxygen side water seal device is directed downhill toward the oxygen side degassing device through the oxygen side overflow pipeline.

[0016] Preferably, a hydrogen concentration detection alarm and a hydrogen side interlock cut-off valve are provided in the hydrogen side degassing device, and the hydrogen side interlock cut-off valve is used to control the switch of the liquid phase outlet of the hydrogen side degassing device.

[0017] Preferably, an oxygen concentration detection alarm and an oxygen side interlock cut-off valve are provided in the oxygen side degassing device, and the oxygen side interlock cut-off valve is used to control the switch of the liquid phase outlet of the oxygen side degassing device.

[0018] Preferably, a liquid level monitoring device and a liquid level alarm are provided in the waste alkali collection tank.

[0019] Preferably, the outlet of the spent alkali pump is provided with a return line to the spent alkali collection tank.

[0020] Beneficial effects: The utility model discloses a zero-emission device for alkaline wastewater from water electrolysis to hydrogen. Through the reasonable design of the emission recovery device, not only can the alkaline wastewater from water electrolysis to hydrogen be collected and reused to achieve zero emission of alkaline wastewater, but also the alkaline wastewater on the hydrogen side and the oxygen side can be water-sealed and degassed respectively, so that the alkaline wastewater can be removed of hydrogen and oxygen respectively before entering the wastewater collection system, thereby avoiding the mixing of hydrogen and oxygen to form explosive gas, improving the safety performance, being conducive to meeting environmental protection requirements, saving investment and land occupation, and having strong feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the device structure of this embodiment 1;

[0022] In the figure: 1. Water seal device on hydrogen side; 2. Desalted water pipeline on hydrogen side; 3. Alkali wastewater main pipe on hydrogen side; 4. Vent pipeline on hydrogen side; 5. Flame arrester; 6. Overflow pipeline on hydrogen side; 7. Degassing device on hydrogen side; 8. Liquid phase outlet pipeline on hydrogen side; 9. Water seal device on oxygen side; 10. Desalted water pipeline on oxygen side; 11. Alkali wastewater main pipe on oxygen side; 12. Vent pipeline on oxygen side; 13. Overflow pipeline on oxygen side; 14. Degassing device on oxygen side; 15. Liquid phase outlet pipeline on oxygen side; 16. Waste alkali collecting tank; 17. Vent pipeline; 18. Inlet pipeline; 19. Waste alkali pump. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0024] Example 1

[0025] A zero-discharge device for alkaline wastewater for hydrogen production by water electrolysis, comprising a hydrogen side water seal device 1, a hydrogen side degassing device 7, a waste alkali collection tank 16, a waste alkali pump 19, an oxygen side water seal device 9, and an oxygen side degassing device 14, wherein:

[0026] The inlet ends of the hydrogen side water seal device 1 are respectively connected with the hydrogen side desalted water pipeline 2 and the hydrogen side alkaline wastewater main pipe 3, the gas phase outlet of the hydrogen side water seal device 1 is connected with the hydrogen side venting pipeline 4, the overflow port of the hydrogen side water seal device 1 is connected with the hydrogen side degassing device 7 via the hydrogen side overflow pipeline 6, and the overflow port of the hydrogen side water seal device 1 is downhill to the hydrogen side degassing device 7 via the hydrogen side overflow pipeline 6, and the hydrogen side liquid phase outlet pipeline 8 of the hydrogen side degassing device 7 is downhill and extends inward to below the liquid level in the waste alkali collecting tank 16; in this embodiment 1, the hydrogen side alkaline wastewater flows downhill along the hydrogen side alkaline wastewater main pipe 3 to the hydrogen side water seal device 1, a flame arrester 5 is installed on the hydrogen side venting pipeline 4, and a hydrogen concentration detection alarm and a hydrogen side interlocking cut-off valve are provided in the hydrogen side degassing device 7, and the hydrogen side interlocking cut-off valve is used to control the switch of the liquid phase outlet of the hydrogen side degassing device.

[0027] The inlet end of the oxygen side water seal device 9 is respectively connected with the oxygen side desalted water pipeline 10 and the oxygen side alkaline wastewater main pipe 11, the gas phase outlet of the oxygen side water seal device 9 is connected with the oxygen side venting pipeline 12, the overflow port of the oxygen side water seal device 9 is connected with the oxygen side degassing device 14 via the oxygen side overflow pipeline 13, and the overflow port of the oxygen side water seal device 9 is downhill to the oxygen side degassing device 14 via the oxygen side overflow pipeline 13, and the oxygen side liquid phase outlet pipeline 15 of the oxygen side degassing device 14 is downhill and extends inward to below the liquid level in the waste alkali collecting tank 16; in the present embodiment 1, the oxygen side alkaline wastewater is downhill along the oxygen side alkaline wastewater main pipe 11 to the oxygen side water seal device 9, and an oxygen concentration detection alarm and an oxygen side interlocking cut-off valve are provided in the oxygen side degassing device, and the oxygen side interlocking cut-off valve is used to control the switch of the liquid phase outlet of the oxygen side degassing device 14.

[0028] The vent line 17 of the waste alkali collection tank 16 is connected to the atmosphere, and the waste alkali pump 19 (preferably a self-priming pump) extends downhill through the inlet pipeline 18 and inward to below the liquid level in the waste alkali collection tank 16. The outlet of the waste alkali pump 19 is connected to any one of the water replenishment tank, the alkali preparation tank or the alkali transport tank truck. The outlet of the waste alkali pump 19 is provided with a return line to the waste alkali collection tank 16, which can realize the pump liquid withdrawal.

[0029] In this embodiment 1, the hydrogen-side degassing device 7 and the oxygen-side degassing device 14 are both arranged indoors, and are also suitable for outdoor use, and the waste alkali collection tank 16 is installed below the ground. In the present utility model, the installation positions of the hydrogen-side degassing device, the oxygen-side degassing device and the waste alkali collection tank 16 can be but are not limited to the above positions, and can be selectively arranged by those skilled in the art according to actual needs.

[0030] In this embodiment 1, the hydrogen side vent pipeline 4, the flame arrester 5 and the oxygen side vent pipeline 12 can be shared by the whole plant, and the specific connection can be selectively set by those skilled in the art according to actual needs, which belongs to conventional technology and is not described in detail.

[0031] On the basis of Example 1, a liquid level monitoring device and a liquid level alarm may also be provided in the waste alkali collection tank 16, wherein the liquid level monitoring device is used to monitor the liquid level height in the waste alkali collection tank 16 in real time, and the liquid level alarm is used to alarm for liquid levels lower than or higher than a preset value, thereby improving the safety performance of wastewater recovery.

[0032] The specific method of using the device of the utility model to achieve zero discharge of alkaline wastewater from water electrolysis to produce hydrogen is as follows:

[0033] (1) All hydrogen-containing wastewater and hydrogen-containing waste alkali in water electrolysis hydrogen production are combined into the hydrogen-side alkali wastewater main pipe 3, and are introduced into the hydrogen-side water seal device 1 through the hydrogen-side alkali wastewater main pipe 3; all oxygen-containing wastewater and oxygen-containing waste alkali in water electrolysis hydrogen production are combined into the oxygen-side alkali wastewater main pipe 11, and are introduced into the oxygen-side water seal device 9 through the oxygen-side alkali wastewater main pipe 11.

[0034] (2) Desalted water is continuously added to the hydrogen side water seal device 1 and the oxygen side water seal device 9 through the hydrogen side desalted water pipeline 2 and the oxygen side desalted water pipeline 10, respectively, to ensure that the water seal is effective.

[0035] (3) The alkaline wastewater on the hydrogen side and the alkaline wastewater on the oxygen side overflow to the hydrogen side degassing device 7 and the oxygen side degassing device 14 through the overflow ports of the hydrogen side water seal device 1 and the oxygen side water seal device 9 respectively.

[0036] (4) The hydrogen-side degassing device 7 and the oxygen-side degassing device 14 release and remove the trace hydrogen and oxygen dissolved in the alkaline wastewater on the hydrogen side and the alkaline wastewater on the oxygen side, respectively. The removed trace hydrogen and oxygen can be directly discharged into the atmosphere.

[0037] (5) The hydrogen concentration detection alarm in the hydrogen-side degassing device 7 and the oxygen concentration detection alarm in the oxygen-side degassing device 14 respectively monitor the gas released from the wastewater in real time and give an alarm, and according to the monitored gas concentration information, the hydrogen-side interlock shut-off valve and the oxygen-side interlock shut-off valve are used to control the switches of the liquid phase outlets of the hydrogen-side degassing device 7 and the oxygen-side degassing device 14 respectively.

[0038] (6) The alkali-containing wastewater in the hydrogen-side degassing device 7 and the oxygen-side degassing device 14 enters the waste alkali collection tank through the hydrogen-side liquid phase outlet pipeline 8 and the oxygen-side liquid phase outlet pipeline 15 respectively provided inwardly.

[0039] (7) The alkali-containing wastewater in the waste alkali collection tank 16 is pumped out by the waste alkali pump and sent to the water replenishment tank / alkali preparation tank / alkali transport tank truck to increase operational flexibility.

[0040] In the present invention, the hydrogen side water seal device, the oxygen side water seal device, the fire arrester device and the waste alkali pump are all existing devices, so they are not described in detail.

[0041] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A zero-discharge device for alkaline wastewater for hydrogen production by water electrolysis, characterized in that: It includes a hydrogen side water seal device, a hydrogen side degassing device, a waste alkali collection tank, a waste alkali pump, an oxygen side water seal device, and an oxygen side degassing device, wherein: The inlet end of the hydrogen side water seal device is respectively connected to the hydrogen side desalted water pipeline and the hydrogen side alkaline wastewater main pipe, the gas phase outlet of the hydrogen side water seal device is connected to the hydrogen side vent pipeline, the overflow port of the hydrogen side water seal device is connected to the hydrogen side degassing device through the hydrogen side overflow pipeline, and the hydrogen side liquid phase outlet pipeline of the hydrogen side degassing device is downhill and extends inward to the waste alkali collection tank; The inlet end of the oxygen side water seal device is respectively connected to the oxygen side desalted water pipeline and the oxygen side alkaline wastewater main pipe, the gas phase outlet of the oxygen side water seal device is connected to the oxygen side vent pipeline, the overflow port of the oxygen side water seal device is connected to the oxygen side degassing device via the oxygen side overflow pipeline, and the oxygen side liquid phase outlet pipeline of the oxygen side degassing device is downhill and extends inward to the waste alkali collection tank; The venting pipeline of the waste alkali collecting tank is connected to the atmosphere, the waste alkali pump extends downhill through the inlet pipeline and inwardly into the waste alkali collecting tank, and the outlet of the waste alkali pump is connected to any one of the water replenishment tank, the alkali preparation tank or the alkali transport tank truck.

2. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The alkaline wastewater on the hydrogen side flows downhill along the alkaline wastewater main pipe on the hydrogen side to the water seal device on the hydrogen side.

3. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The alkaline wastewater on the oxygen side flows downhill along the alkaline wastewater main pipe on the oxygen side toward the water seal device on the oxygen side.

4. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: A fire arrester is installed on the hydrogen side venting pipeline.

5. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The overflow port of the hydrogen side water seal device flows downhill to the hydrogen side degassing device through the hydrogen side overflow pipeline.

6. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The overflow port of the oxygen side water seal device flows downhill toward the oxygen side degassing device through the oxygen side overflow pipeline.

7. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The hydrogen side degassing device is provided with a hydrogen concentration detection alarm and a hydrogen side interlock cut-off valve, and the hydrogen side interlock cut-off valve is used to control the switch of the liquid phase outlet of the hydrogen side degassing device.

8. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: An oxygen concentration detection alarm and an oxygen side interlock cut-off valve are arranged in the oxygen side degassing device, and the oxygen side interlock cut-off valve is used to control the switch of the liquid phase outlet of the oxygen side degassing device.

9. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: A liquid level monitoring device and a liquid level alarm are arranged in the waste alkali collection tank.

10. The zero-discharge device for alkaline wastewater for producing hydrogen by water electrolysis according to claim 1, characterized in that: The outlet of the waste alkali pump is provided with a return line to the waste alkali collection tank.

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