CN-122013213-A - Alkaline solution secondary separation circulation system of alkaline electrolytic tank and working method thereof

CN122013213ACN 122013213 ACN122013213 ACN 122013213ACN-122013213-A

Abstract

The invention relates to the technical field of alkaline hydrogen production, and discloses an alkaline solution secondary separation and circulation system of an alkaline electrolytic tank and a working method thereof. The system comprises an alkaline electrolytic tank, an anode side and cathode side gas-liquid separation tank, an anode side and cathode side secondary gas-liquid separation tank, an alkali liquor circulating pump and a valve group. The system can be switched between a conventional mixed circulation mode and a secondary separation mixed circulation mode by selectively opening and closing the valve group, so as to realize secondary gas-liquid separation of the circulating alkali liquor on the anode side and the cathode side, and the circulation flow of the alkali liquor is regulated in the secondary separation mixed circulation mode according to the change of the hydrogen content in the oxygen in the gas on the anode side. According to the method, through switching of the gas-liquid separation mode and cooperative adjustment of the alkali liquor circulation flow, the content of dissolved gas in the alkali liquor under different operation conditions is reduced, the operation safety and stability of the alkaline electrolytic tank are improved, and the adaptability of the electrolytic hydrogen production system to renewable energy sources is improved.

Inventors

FANG HAO
WANG LIANGLIANG
WANG TAO
YIN CHONG
GAO WENLONG
WANG XIAODAN
WANG YICHENG
CHEN CHEN

Assignees

中国电建集团华东勘测设计研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20260113

Claims (10)

1. The alkali liquor circulation system for coupling alkali liquor secondary separation is characterized by comprising an alkaline electrolytic tank (1), an anode side gas-liquid separation tank (2), a cathode side gas-liquid separation tank (3), an anode side secondary gas-liquid separation tank (4), a cathode side secondary gas-liquid separation tank (5), a filter (6), an alkali liquor circulation pump (7), a heat exchanger (8), a valve group and connecting pipelines, wherein the alkali liquor circulation system is provided with a conventional mixed circulation mode and a secondary separation mixed circulation mode, wherein in the conventional mixed circulation mode, alkali liquor is subjected to mixed circulation after passing through the anode side gas-liquid separation tank (2) and the cathode side gas-liquid separation tank (3), in the secondary separation mixed circulation mode, alkali liquor enters the anode side secondary gas-liquid separation tank (4) and the cathode side secondary gas-liquid separation tank (5) respectively after being subjected to secondary gas-liquid separation, wherein in the alkaline electrolytic tank (1) is provided with a mixed circulation mode, when the oxygen content in the anode side is monitored by the conventional mixed circulation mode is switched, and when the oxygen content in the alkaline electrolytic tank (1) is subjected to the mixed circulation mode is switched to the mixed circulation mode.
2. The alkaline secondary separation circulation system of the alkaline hydrogen production electrolytic tank according to claim 1, wherein the valve group comprises a first valve (9), a second valve (10), a third valve (11), a fourth valve (12), a fifth valve (13), a sixth valve (14), a seventh valve (15) and an eighth valve (16).
3. The alkaline secondary separation circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein an anode electrolyte outlet of the alkaline electrolytic tank (1) is connected with an inlet of an anode side gas-liquid separation tank (2), an alkaline liquid outlet of the anode side gas-liquid separation tank (2) is connected with a first valve (9) and a second valve (10) through connecting pipelines, the first valve (9) is connected with an outlet pipeline of a filter (6) and a third valve (11) through connecting pipelines, the second valve (10) is connected with an inlet of an anode side secondary gas-liquid separation tank (4) through connecting pipelines, an outlet of the anode side secondary gas-liquid separation tank (4) is connected with an outlet pipeline of a cathode side secondary gas-liquid separation tank (5) and the filter (6) through pipelines, and an outlet of the filter is connected with an alkaline liquid circulating pump (7) through pipelines.
4. The alkaline secondary separation circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein a cathode electrolyte outlet of the alkaline electrolytic tank (1) is connected with an inlet of a cathode side gas-liquid separation tank (3), an alkaline liquid outlet of the cathode side gas-liquid separation tank (3) is connected with a third valve (11) and a fourth valve (12) through connecting pipelines, the third valve (11) is connected with an outlet pipeline of the first valve (9) through connecting pipelines, the fourth valve (12) is connected with an inlet of a cathode side secondary gas-liquid separation tank (5) through connecting pipelines, and an alkaline liquid outlet of the cathode side secondary gas-liquid separation tank (5) is connected with an alkaline liquid outlet pipeline of an anode side secondary gas-liquid separation tank (4) through pipelines.
5. The alkaline secondary separation circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein in the normal mixed circulation mode, the first valve (9) and the third valve (11) are opened, the second valve (10), the fourth valve (12), the fifth valve (13), the sixth valve (14), the seventh valve (15) and the eighth valve (16) are closed, the anode side secondary gas-liquid separation tank (4) and the cathode side secondary gas-liquid separation tank (5) are in an idle state, and in the secondary separation mixed circulation mode, the second valve (10), the fourth valve (12), the fifth valve (13), the sixth valve (14), the seventh valve (15) and the eighth valve (16) are opened, the first valve (9) and the third valve are closed (11), and the anode side secondary gas-liquid separation tank (4) and the cathode side secondary gas-liquid separation tank (5) are put into an operating state.
6. The alkaline secondary separation circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein the types of the second valve and the fourth valve are preferably pressure reducing valves, and the types of the sixth valve and the eighth valve are preferably pressure control valves or check valves.
7. The alkaline secondary separation and circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein the valve group is connected with an upper computer, and the upper computer is used for controlling opening and closing of each valve in the valve group.
8. The alkaline secondary separation and circulation system of the alkaline hydrogen production electrolytic tank according to claim 2, wherein the upper computer is further connected with an alkaline circulating pump (7), and is used for changing the flow rate of the alkaline circulating pump when the input power of an external power supply changes.
9. The alkaline secondary separation and circulation system of the alkaline hydrogen production electrolytic tank according to claim 7, wherein the upper computer is used for changing the flow rate of an alkaline circulation pump, and specifically comprises: when the alkali liquor circulation mode is a conventional mixed circulation mode, the flow of the alkali liquor circulation pump is kept to be a set flow value corresponding to rated current; When the alkali liquor circulation mode is a secondary separation mixing circulation mode and the content of hydrogen contained in oxygen in the anode side gas is monitored to continuously rise and exceeds a preset time threshold, the upper computer enables the circulation flow of the alkali liquor circulation pump (7) to be reduced by controlling the valve on-off state related to the flow regulation of the alkali liquor circulation pump (7) in the valve group.
10. Alkaline secondary separation and circulation system of an alkaline hydrogen production electrolyzer according to claim 9, characterized in that it switches alkaline circulation modes by means of the valve group according to the power load state of the alkaline electrolyzer (1), in particular: When the alkaline electrolyzer (1) is operated at rated power load, the lye circulation system operates in a conventional mixed circulation mode; when the alkaline electrolytic tank (1) operates under low power load and the content of hydrogen in oxygen in anode side gas is higher than a preset threshold value, the upper computer switches the alkali liquor circulation system to a secondary separation mixing circulation mode by controlling the valve on-off state related to the adjustment of the secondary separation mixing circulation mode in the valve group.

Description

Alkaline solution secondary separation circulation system of alkaline electrolytic tank and working method thereof Technical Field The present disclosure relates to a gas-liquid separation system for producing hydrogen by alkaline electrolysis of water, in particular to an alkaline solution secondary separation circulation system of an alkaline electrolytic tank and a working method thereof. Background The current alkaline electrolysis hydrogen production technology is a hydrogen production technology with scale, economy and flexibility suitable for renewable energy power generation situations. However, since the alkaline electrolysis hydrogen production technology adopts a mixed circulation mode of alkali liquor, the electrolytes on the anode side and the cathode side are in a completely mixed state during the operation. When the output of renewable energy sources is lower, the electrolytic tank operates in a low-load zone, the gas production of the anode and the cathode obviously becomes smaller, but the gas cross quantity brought by alkali liquor mixing circulation and membrane permeation is not changed greatly, so that the gas mixing of the anode side and the cathode side is serious, serious accidents are easily caused when the gas mixture enters an explosion zone, and the method is also a root cause for the narrow operation range of an alkaline water electrolysis hydrogen production system. There are several approaches to solve the problem, one approach is to develop a membrane with better gas barrier performance, reduce the cross gas amount caused by membrane permeation, but cause obvious cost rise, and the reduction of membrane gas permeation amount is often accompanied by the increase of electric resistance, thereby affecting the energy efficiency of the electrolytic cell, one approach is to develop an alkaline electrolysis hydrogen production system with independent circulation of alkaline solution, but when the electrolytic cell is in variable load operation, the fluctuation of gas production on the cathode and anode sides is larger, thereby bringing great challenges to the liquid level control of the electrolytic cell hydrogen production system, and one approach is to reduce the circulation amount of alkaline solution at low load, but the reduction of alkali solution circulation amount causes accumulation of gas on the surface of an electrode, causes the increase of activation overpotential, thereby causing the increase of energy consumption of the electrolytic cell and accelerating the loss of electrode materials. Disclosure of Invention The purpose of the disclosure is to provide a secondary alkaline solution separation and circulation system of an alkaline electrolytic tank and a working method thereof, which solve the problem that the gas mixing at the anode side and the cathode side of the alkaline electrolytic tank is serious when the alkaline electrolytic tank is operated under low cost and easy operation. The present disclosure is realized by the following technical scheme: The alkali liquor circulation system for coupling alkali liquor secondary separation comprises an alkaline electrolytic tank, an anode side gas-liquid separation tank, a cathode side gas-liquid separation tank, an anode side secondary gas-liquid separation tank, a cathode side secondary gas-liquid separation tank, a filter, an alkali liquor circulation pump, a heat exchanger, a valve group and connecting pipelines, wherein the alkali liquor circulation system is provided with a conventional mixing circulation mode and a secondary separation mixing circulation mode, alkali liquor is subjected to mixing circulation after passing through the anode side gas-liquid separation tank and the cathode side gas-liquid separation tank in the conventional mixing circulation mode, alkali liquor is respectively fed into the anode side secondary gas-liquid separation tank and the cathode side secondary gas-liquid separation tank in the secondary separation mixing circulation mode, and then is subjected to mixing circulation, a monitoring device for monitoring the content of hydrogen in oxygen is arranged on the anode side in the alkaline electrolytic tank, when the content of hydrogen in the anode side gas exceeds a preset threshold value, the alkali liquor circulation system is switched from the conventional mixing circulation mode to the secondary separation circulation mode, and the frequency conversion circulation pump is adopted for alkali liquor circulation mode. Further, the valve group comprises a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve and an eighth valve. Further, the anode electrolyte outlet of the alkaline electrolytic tank is connected with the inlet of the anode side gas-liquid separation tank, the alkali liquor outlet of the anode side gas-liquid separation tank is connected with the first valve and the second valve through connecting pipelines, the first