Flow battery gas self-stratification waste gas treatment system

Abstract

The invention belongs to the technical field of flow battery energy storage, and particularly relates to a flow battery gas self-stratification waste gas treatment system which can realize efficient recovery of useful components in waste gas and thorough elimination of harmful substances on the premise of not destroying electrolyte ion balance. Therefore, the double problems of battery performance degradation and harmful gas leakage are solved at the same time. The acid radical ions in the waste gas are efficiently recycled and returned, the problem of electrolyte ion unbalance caused by waste gas treatment is fundamentally avoided, and the performance and the service life of the battery are maintained; through closed circulation and efficient purification in the system, the risk that poisonous and harmful gas leaks to the environment is greatly reduced, and the safety and environmental friendliness of the system are improved; the gas-liquid separation and reaction process is optimized, and the recovery efficiency and the overall treatment efficiency of useful components in the waste gas are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of flow battery energy storage technology, specifically relating to a flow battery gas self-stratification waste gas treatment system. Background Technology

[0002] In recent years, flow batteries have gradually become a new option for large-scale, long-term energy storage due to their inherent high safety and long cycle life, making them particularly suitable for large-scale energy storage power stations. However, one problem with flow batteries is that during charging and discharging, due to localized overcharging, gas release inside the battery stack is inevitable. Taking common hydrochloric acid-based or hydrochloric acid-added flow batteries as an example, overcharging can lead to the release of chlorine and hydrogen. Chlorine is a toxic and corrosive gas that poses a potential hazard to personnel and equipment, while hydrogen is a flammable and explosive gas that carries the risk of explosion. Therefore, the rational treatment of waste gases is extremely important.

[0003] Currently, common treatment methods include direct discharge of waste gas, absorption with alkaline liquids, adsorption, and reuse. Direct discharge of waste gas poses a threat to personnel and the environment, while absorption and adsorption lead to the loss of chlorine in the electrolyte and an imbalance in the electrolyte's valence state. Reuse methods require the simultaneous treatment of multiple gases while maintaining a constant content of acid ions in the electrolyte, which remains a challenging and urgent problem to be solved. Existing technologies for the treatment of waste gas from flow batteries are not sufficiently discussed or researched.

[0004] Currently, common technologies for treating exhaust gas from flow batteries mainly include adsorption, direct recycling, and chemical absorption. For example, while adsorption purification devices equipped with specific filter materials (such as the scheme disclosed in CN218794641U) can capture exhaust gas, they also lead to the selective adsorption of acid radicals in the electrolyte. Long-term operation of these devices will disrupt the electrolyte's ion balance, causing battery capacity decay and increased side reactions, ultimately accelerating stack failure. Another approach is to directly introduce the exhaust gas into the stack circuit for recovery (such as CN110858659A), using devices like Venturi tubes to introduce the positive electrode exhaust gas into the negative electrode electrolyte. While this method aims to reuse the exhaust gas, the limited gas-liquid contact area and incomplete absorption allow air bubbles to easily enter the stack, resulting in decreased stack performance and low overall purification efficiency. In addition, some technologies use the method of extracting the exhaust gas and then absorbing and treating it with an alkaline solution (such as sodium hydroxide) (such as CN118983483A). Although this method can neutralize acidic gases, it will also cause the electrolyte system to lose acid radical ions, resulting in an imbalance of electrolyte components, which in turn affects the long-term operational stability and cycle life of the battery.

[0005] In summary, existing technologies for treating flow battery exhaust gases generally face the following core contradictions: On the one hand, external discharge or purification of the exhaust gases can easily lead to irreversible loss of key electrolyte components (especially acid radicals), disrupting the electrolyte's chemical balance and directly affecting battery capacity and lifespan. On the other hand, attempts to recover the gases internally face technical bottlenecks such as low gas-liquid mass transfer efficiency, incomplete absorption, and the risk of introducing air bubbles, and cannot effectively prevent the environmental and safety risks associated with potential leaks of harmful gases. Therefore, there is an urgent need for an integrated treatment solution that can efficiently and safely recover effective components and purify harmful substances from exhaust gases without disrupting the electrolyte's ion balance. Summary of the Invention

[0006] In view of this, the present invention provides a flow battery gas self-stratification exhaust gas treatment system, which can achieve efficient recovery of useful components and complete elimination of harmful substances in exhaust gas without disrupting the electrolyte ion balance, thereby simultaneously solving the dual problems of battery performance degradation and harmful gas leakage.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A flow battery gas self-stratification exhaust gas treatment system includes a gas storage tank, a gas pump, and a gas disperser; The gas storage tank is internally divided into an upper gas chamber and a lower gas chamber by a horizontally arranged partition. The upper air chamber is equipped with a nitrogen replacement port and an exhaust valve; The lower air chamber is connected to the upper air chamber via a Venturi tube; The inlet end of the air pump is connected to the gas phase space of the positive electrolyte storage tank and / or negative electrolyte storage tank of the flow battery system through a pipeline, and the outlet end is connected to the upper gas chamber of the gas storage tank. The gas disperser is installed inside the negative electrode electrolyte storage tank of the flow battery system and is connected to the lower gas chamber of the gas storage tank through a pipeline.

[0008] The partition is fixedly installed in the middle or upper part of the inner wall of the gas storage tank to promote the stratification of the mixed waste gas entering the gas storage tank in the upper and lower gas chambers based on density differences.

[0009] The Venturi tube has one end opening located at the upper part of the lower gas chamber for extracting low-density gas accumulated there; the other end opening is connected to the upper gas chamber for transporting the low-density gas to the upper gas chamber.

[0010] The gas disperser is one of a microporous aeration head, a sintered metal diffuser, or a porous ceramic disperser.

[0011] The system further includes a first valve, which is disposed on the pipeline connecting the gas disperser and the lower gas chamber.

[0012] The system further includes a second valve, which is disposed on a pipeline connecting the upper gas chamber and the gas phase space of the positive electrolyte storage tank.

[0013] The inlet of the air pump is connected to the gas phase space of the positive electrolyte storage tank and the negative electrolyte storage tank respectively through a three-way valve or two parallel branch pipelines.

[0014] The exhaust valve is a solenoid valve or a pneumatic valve and is connected to a controller; the upper air chamber is also equipped with a pressure sensor, which is electrically connected to the controller and is used to control the exhaust valve to open and start nitrogen replacement when the hydrogen enrichment pressure is detected to reach a set threshold.

[0015] The partition is a circular or square plate, and its edges are fixed and sealed to the inner wall of the gas storage tank by welding or sealing rings.

[0016] The flow battery system is a vanadium redox flow battery system.

[0017] Beneficial effects 1. This invention achieves efficient recovery and return of acid radical ions in waste gas, fundamentally avoiding the problem of electrolyte ion imbalance caused by waste gas treatment, and maintaining battery performance and lifespan; through closed-loop circulation and efficient purification within the system, it greatly reduces the risk of toxic and harmful gases leaking into the environment, improving system safety and environmental friendliness; and by optimizing the gas-liquid separation and reaction process, it significantly improves the recovery efficiency of useful components in waste gas and the overall treatment efficiency.

[0018] 2. The system of the present invention utilizes acid radical ions through a recycling method to improve the imbalance of acid radical ions in the electrolyte; the system of the present invention can recycle and reuse harmful gases, reducing the risk of gas leakage; the system of the present invention can efficiently recover reusable gases from waste gas.

[0019] 3. This invention guides acidic gases (such as chlorine and hydrogen chloride) in the waste gas to the negative electrode electrolyte storage tank, and through a gas disperser, allows them to fully contact, dissolve, and be reduced and absorbed by the electrolyte, thereby directly and efficiently replenishing the key acid radical ions into the electrolyte circulation system. This process achieves in-situ recovery of valuable components from the waste gas, fundamentally avoiding the irreversible loss of electrolyte acid radical ions and ion imbalance problems caused by traditional adsorption or alkaline absorption methods, thus ensuring the capacity stability of the flow battery and extending its cycle life.

[0020] 4. The entire processing system of this invention forms a closed gas circulation loop in parallel with the fuel cell stack circuit, driven by a gas pump. All harmful gases (such as chlorine) are treated within the system, and acidic components are absorbed by the electrolyte, greatly eliminating the risk of toxic gas leakage into the environment. The final enriched hydrogen is diluted and discharged using a controlled nitrogen replacement method, significantly reducing the risk of combustion and explosion. This design greatly improves the overall safety and environmental friendliness of the flow battery system.

[0021] 5. This invention utilizes the density differences of gases to achieve efficient and automated physical separation of hydrogen and heavier acidic gases through partition separation and Venturi tube diversion. The acidic gases enter the lower chamber under negative pressure and accumulate at the bottom, then are concentrated and sent to a gas disperser for efficient absorption; while hydrogen is actively extracted by the Venturi tube and accumulated in the upper chamber. This density-stratified design increases the contact efficiency and specificity between the target gas and the treatment medium (electrolyte), avoids cross-contamination caused by gas mixing, and thus significantly improves the recovery efficiency of useful components and overall purification performance.

[0022] 6. The system of this invention does not require complex filter materials or external chemical reagents. It mainly relies on physical stratification and electrochemical absorption principles to operate, resulting in a relatively simple structure and stable and reliable operation. The system can adaptively handle waste gas with different components and concentrations generated by changes in charge and discharge states, achieving dynamic balance through automatic gas stratification and circulation. Furthermore, by combining pressure sensing and automatic control, it can achieve automated management of hydrogen enrichment and safe emission, reducing the difficulty of operation and maintenance and the risks of human operation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the flow battery exhaust gas treatment system of the present invention.

[0024] Figure 2 This is a schematic diagram of the gas flow direction in the flow battery exhaust gas treatment system of the present invention.

[0025] Figure 3 This is a schematic diagram of nitrogen replacement in the flow battery exhaust gas treatment system of the present invention.

[0026] Figure 4 This is a schematic diagram of the initial state of the exhaust gas treatment system for the flow battery of the present invention.

[0027] Figure 5 This is a schematic diagram of the intermediate state 1 of the exhaust gas treatment system of the flow battery of the present invention.

[0028] Figure 6 This is a schematic diagram of the intermediate state 2 of the exhaust gas treatment system of the flow battery of the present invention.

[0029] Figure 7This is a schematic diagram of the exhaust gas treatment system of the flow battery of the present invention at the end of exhaust gas treatment. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] This invention provides a flow battery exhaust gas treatment system, such as... Figure 1 As shown, the system includes a gas storage tank, a gas pump, a gas disperser, and piping connecting the positive and negative electrolyte storage tanks. The gas storage tank is divided into upper and lower chambers by a partition, which are directly connected by a venturi tube. The upper chamber is equipped with a nitrogen purging port and an exhaust valve.

[0032] The gas storage tank is where gas separation and collection are performed. An air pump introduces waste gas from the storage tank into it. A gas disperser evenly disperses the acidic gas introduced into the negative electrode electrolyte, ensuring it reacts and is absorbed effectively. A partition divides the storage tank into upper and lower chambers. A venturi tube connects the upper and lower chambers, transferring gas from the lower chamber to the upper chamber. A nitrogen purging port introduces nitrogen into the upper chamber, replacing the gas there. An exhaust valve discharges the gas from the upper chamber via nitrogen purging. The gas flow direction in the flow battery waste gas treatment system is as follows: Figure 2 As shown.

[0033] Optionally, the gas disperser is one of a microporous aeration head, a sintered metal diffuser, or a porous ceramic disperser.

[0034] Furthermore, the system also includes a first valve, which is disposed on the pipeline connecting the gas disperser and the lower gas chamber.

[0035] Furthermore, the system also includes a second valve, which is disposed on the pipeline connecting the upper gas chamber and the gas phase space of the positive electrolyte storage tank.

[0036] Preferably, the inlet of the air pump is connected to the gas phase space of the positive electrolyte storage tank and the negative electrolyte storage tank respectively through a three-way valve or two parallel branch pipelines.

[0037] Optionally, the exhaust valve is a solenoid valve or a pneumatic valve and is connected to a controller; the upper air chamber is also provided with a pressure sensor, which is electrically connected to the controller and is used to control the exhaust valve to open and start nitrogen replacement when the hydrogen enrichment pressure is detected to reach a set threshold.

[0038] Optionally, the partition is a circular or square plate, and its edges are fixed and sealed to the inner wall of the gas storage tank by welding or sealing rings.

[0039] In this embodiment, the flow battery system is an all-vanadium redox flow battery system.

[0040] Taking an acidic flow battery as an example, the gases can be classified into hydrogen, neutral gas (nitrogen), and oxidizing gas according to their density from lowest to highest. The gases will stratify from top to bottom in each gas chamber and electrolyte storage tank according to their density from lowest to highest. The waste gas treatment process is as follows: 1. The acidic gases generated in the fuel cell stack will accumulate above the surface of the positive electrode electrolyte tank and mix with hydrogen and neutral gases.

[0041] 2. The acidic gas mixture is introduced into the lower chamber of the gas storage tank for secondary separation.

[0042] 3. The acidic gas in the lower layer of the lower gas chamber is introduced into the negative electrode electrolyte. After being dispersed by the gas disperser, most of the acidic gas is absorbed by the negative electrode electrolyte.

[0043] 4. The remaining gases accumulate above the surface of the electrolyte in the negative electrode tank and mix with the hydrogen generated by the negative electrode stack.

[0044] 5. Hydrogen gas from the upper layer of the negative electrode electrolyte storage tank is pumped into the upper gas chamber of the gas storage tank. At the same time, hydrogen gas from the upper layer of the lower gas chamber of the gas storage tank is also pumped into the upper gas chamber of the gas storage tank via a Venturi tube.

[0045] 6. The hydrogen mixture is introduced into the upper gas chamber of the gas storage tank for separation, and the acidic gas is introduced into the positive electrode electrolyte storage tank through the lower pipeline of the upper gas chamber.

[0046] The exhaust gas treatment system ultimately achieves the recovery and reuse of acidic gases and the enrichment of hydrogen. When the amount of hydrogen in the upper chamber of the storage tank reaches a critical value, it needs to be discharged through nitrogen replacement. A large amount of nitrogen is introduced through the nitrogen replacement port, and the exhaust valve is opened to dilute the hydrogen significantly before discharging it from the storage tank. The nitrogen replacement process in this invention's flow battery exhaust gas treatment system is as follows: Figure 3 As shown.

[0047] The working process of the system of the present invention is shown by taking the exhaust gas treatment of a typical vanadium redox flow battery containing hydrochloric acid electrolyte as an example.

[0048] The initial state of the system is as follows Figure 4 As shown, due to the addition of hydrochloric acid to the electrolyte, hydrogen gas (in the negative electrode electrolyte tank) and chlorine gas (in the positive electrode electrolyte tank) will inevitably be generated and accumulate in the tanks during the operation of the vanadium redox flow battery. Simultaneously, hydrochloric acid will also volatilize and release hydrogen chloride gas, which will also fill the tanks. At this time, the gaseous state of the flow battery system is as follows: Figure 2 (The flow battery was filled with nitrogen before operation.) The gas accumulates in the storage tank and automatically stratifies according to its relative density.

[0049] The gas pump is turned on, and the gas in the system begins to circulate. The gas enters the next container through the corresponding pipeline, entering an intermediate state. Initially, in intermediate state 1, chlorine and hydrogen chloride gases enter the lower layer of the storage tank and accumulate there. Hydrogen gas, via the gas pump, enters the upper layer of the storage tank and accumulates there. Intermediate state 1 is as follows... Figure 5 As shown.

[0050] As the gas pump operates, some gases may enter other containers. Taking hydrogen as an example, after hydrogen enters the storage tank through the gas pump, a small portion may enter the positive electrode electrolyte storage tank and then enter the lower layer of the storage tank along with the gas, entering intermediate state 2. Intermediate state 2 is as follows... Figure 6 As shown. In intermediate state 2, hydrogen enters each container and is distributed in the upper layer of each container. The hydrogen in the lower layer of the gas storage tank will enter the upper layer of the gas storage tank through the Venturi tube. The hydrogen in the positive electrode electrolyte storage tank will also automatically rise and return to the upper gas chamber of the gas storage tank after the exhaust valve is opened.

[0051] Through continuous gas circulation, chlorine and hydrogen chloride gases are reintegrated into the electrolyte as much as possible, while hydrogen is enriched and collected in the upper gas chamber of the storage tank for final discharge.

[0052] Inevitably, some hydrogen chloride and chlorine gases will not be absorbed and will remain in the electrolyte storage tank. Ultimately, hydrogen gas will accumulate in the upper chamber of the storage tank and will be discharged via nitrogen purging. The exhaust gas treatment state of the flow battery exhaust gas treatment system of this invention at the end of treatment is as follows: Figure 7 As shown.

[0053] This invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered within the scope of protection of this invention.

Claims

1. A flow battery gas self-stratification exhaust gas treatment system, characterized in that, Includes gas storage tanks, gas pumps, and gas dispersers; The gas storage tank is internally divided into an upper gas chamber and a lower gas chamber by a horizontally arranged partition. The upper air chamber is equipped with a nitrogen replacement port and an exhaust valve; The lower air chamber is connected to the upper air chamber via a Venturi tube; The inlet end of the air pump is connected to the gas phase space of the positive electrolyte storage tank and / or negative electrolyte storage tank of the flow battery system through a pipeline, and the outlet end is connected to the upper gas chamber of the gas storage tank. The gas disperser is installed inside the negative electrode electrolyte storage tank of the flow battery system and is connected to the lower gas chamber of the gas storage tank through a pipeline.

2. The system according to claim 1, characterized in that, The baffle is fixedly installed in the middle or upper part of the inner wall of the gas storage tank to promote the stratification of the mixed waste gas entering the gas storage tank in the upper and lower gas chambers based on density differences.

3. The system according to claim 1, characterized in that, One end of the venturi tube is located at the upper part of the lower gas chamber, used to extract the low-density gas accumulated there; the other end is connected to the upper gas chamber, used to transport the low-density gas to the upper gas chamber.

4. The system according to claim 1, characterized in that, The gas disperser is one of a microporous aeration head, a sintered metal diffuser, or a porous ceramic disperser.

5. The system according to claim 1, characterized in that, The system also includes a first valve, which is disposed on the pipeline connecting the gas disperser and the lower gas chamber.

6. The system according to claim 1, characterized in that, The system also includes a second valve, which is disposed on a pipeline connecting the upper gas chamber and the gas phase space of the positive electrolyte storage tank.

7. The system according to claim 1, characterized in that, The inlet of the air pump is connected to the gas phase space of the positive electrolyte storage tank and the negative electrolyte storage tank respectively through a three-way valve or two parallel branch pipelines.

8. The system according to claim 1, characterized in that, The exhaust valve is a solenoid valve or a pneumatic valve and is connected to a controller; the upper air chamber is also equipped with a pressure sensor, which is electrically connected to the controller and is used to control the exhaust valve to open and start nitrogen replacement when the hydrogen enrichment pressure is detected to reach a set threshold.

9. The system according to claim 2, characterized in that, The partition is a circular or square plate, and its edges are fixed and sealed to the inner wall of the gas storage tank by welding or sealing rings.

10. The system according to any one of claims 1-9, characterized in that, The flow battery system is a vanadium redox flow battery system.

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