System and method for recovering capacity of acid flow battery

Abstract

The invention belongs to the technical field of flow batteries, and discloses an acid flow battery capacity recovery system and method. The system comprises a first centrifugal pump, a first three-way valve, a first gas-liquid reaction device, a second gas-liquid reaction device and a third centrifugal pump, wherein a positive electrode electrolyte in a positive electrode electrolyte storage tank can be pumped into the first gas-liquid reaction device and the second gas-liquid reaction device through the first centrifugal pump and the third centrifugal pump to be subjected to oxidation-reduction reaction with reducing gas; the problem of capacity fading caused by hydrogen evolution of the electrolyte of the acid flow battery can be well solved, and the method is simple to operate, high in economical efficiency and environment-friendly; waste gas and impurities generated in the electrolyte capacity recovery process can be treated, the byproduct elemental sulfur can be obtained, the income of a power station is increased, the operation of the whole system is simpler and more economical, and the construction and maintenance cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid flow batteries, and particularly relates to a system and method for recovering the capacity of an acidic liquid flow battery. BACKGROUND

[0002] Iron-chromium liquid flow battery technology is gradually promoted and is one of long-time energy storage technology routes with great development potential and broad application prospects. For the acidic iron-chromium liquid flow battery technology, in the charging and discharging cycle process, the reaction of divalent iron to trivalent iron occurs in the positive electrode, and the reaction of trivalent chromium to divalent chromium occurs in the negative electrode. Due to the poor reactivity of the negative electrode chromium, hydrogen evolution reaction occurs in the process, which gradually causes the positive electrode to accumulate part of the trivalent iron, and finally causes the electrolyte capacity to decrease.

[0003] Chemical and electrochemical methods can be used to recover the capacity of the positive electrolyte. The chemical method is to add chemical reagents to the positive electrolyte to generate an oxidation-reduction reaction, and organic or inorganic reagents can be used. The electrochemical method is to use the reaction of the reaction stack to generate an electrochemical reaction to reduce the excess trivalent iron in the positive electrolyte.

[0004] The above existing battery capacity recovery methods have problems such as low chemical reaction efficiency (e.g., methanol and oxalic acid reducing agents), and the generation of by-products such as chlorine gas (e.g., hydrochloric acid) in electrochemical reactions, which brings great trouble to subsequent system design and tail gas treatment, and increases the construction and maintenance costs. SUMMARY

[0005] To solve the above problems, the application provides a system and method for recovering the capacity of an acidic liquid flow battery, which adopts the following technical solutions:

[0006] A system for recovering the capacity of an acidic liquid flow battery, comprising a first centrifugal pump, a first three-way valve, a first gas-liquid reaction device, a second gas-liquid reaction device, and a third centrifugal pump.

[0007] The inlet of the first centrifugal pump is in communication with the outlet of the positive electrolyte storage tank, the a end of the first three-way valve is in communication with the outlet of the first centrifugal pump, the b end of the first three-way valve is in communication with the positive electrolyte inlet of the reaction stack, the c end of the first three-way valve is in communication with the top liquid inlet of the first gas-liquid reaction device, and the bottom gas inlet of the first gas-liquid reaction device is in communication with a reducing gas pipeline and an inert gas pipeline.

[0008] The top gas outlet of the first gas-liquid reaction device is in communication with the bottom gas inlet of the second gas-liquid reaction device, the top liquid outlet of the first gas-liquid reaction device is in communication with the inlet of the third centrifugal pump, and the outlet of the third centrifugal pump is in communication with the bottom liquid inlet of the second gas-liquid reaction device.

[0009] Further, the third gas-liquid reaction device, the primary alkali liquid tank, the secondary alkali liquid tank and the fourth centrifugal pump are further included.

[0010] The top gas outlet of the second gas-liquid reaction device is communicated with the bottom gas inlet of the third gas-liquid reaction device, the top liquid inlet of the third gas-liquid reaction device is communicated with the outlet of the fourth centrifugal pump, the inlet of the fourth centrifugal pump is communicated with the primary alkali liquid tank, the bottom gas outlet of the third gas-liquid reaction device is communicated with the bottom gas inlet of the secondary alkali liquid tank, and the top gas outlet of the secondary alkali liquid tank is communicated with the inert gas recovery device.

[0011] Further, the mechanical filter and the second three-way valve are further included.

[0012] The bottom liquid outlet of the first gas-liquid reaction device is communicated with the a end of the second three-way valve, the b end of the second three-way valve is communicated with the bottom liquid outlet of the second gas-liquid reaction device, the c end of the second three-way valve is communicated with the top liquid inlet of the mechanical filter through the first pipeline, the gas inlet of the mechanical filter is communicated with the inert gas pipeline, and the gas outlet of the mechanical filter is communicated with the inert gas recovery device.

[0013] Further, the multi-medium filter, the membrane filter, the third three-way valve and the sixth centrifugal pump are further included.

[0014] The top liquid outlet of the second gas-liquid reaction device is communicated with the a end of the third three-way valve, the c end of the third three-way valve is communicated with the top liquid inlet of the multi-medium filter, the bottom liquid outlet of the multi-medium filter is communicated with the inlet of the sixth centrifugal pump, and the outlet of the sixth centrifugal pump is communicated with the top liquid inlet of the membrane filter.

[0015] Further, the fifth centrifugal pump is further included, the bottom liquid outlet of the mechanical filter is communicated with the inlet of the fifth centrifugal pump, the outlet of the fifth centrifugal pump is communicated with the b end of the third three-way valve through the second pipeline, the second pipeline is communicated with the first pipeline through the third pipeline, and the valve is arranged on the third pipeline.

[0016] Further, the seventh centrifugal pump is further included, the bottom liquid outlet of the membrane filter is communicated with the inlet of the seventh centrifugal pump, and the outlet of the seventh centrifugal pump is communicated with the liquid inlet of the positive electrolyte storage tank.

[0017] Further, the sulfur purification treatment device is further included, the sulfur purification treatment device is used for treating the solid after the mechanical filter is pressed and filtered, and the elemental sulfur is obtained.

[0018] The application further provides a method for recovering the capacity of an acid liquid flow battery, which is realized by the acid liquid flow battery capacity recovery system and includes the following steps:

[0019] The first three-way valve is opened, and the electrolyte in the positive electrolyte storage tank is delivered to the first gas-liquid reaction device at a set flow rate by the first centrifugal pump, and a reducing gas is delivered to the first gas-liquid reaction device, so that the reducing gas and the ferric chloride in the electrolyte undergo a first redox reaction.

[0020] The electrolyte after the first redox reaction in the first gas-liquid reaction device is delivered to the second gas-liquid reaction device by the third centrifugal pump, and the gas after the reaction in the first gas-liquid reaction device enters the second gas-liquid reaction device from the bottom of the second gas-liquid reaction device, and undergoes a second redox reaction with the electrolyte after the first redox reaction.

[0021] Further, the method further comprises the following steps:

[0022] When it is determined that the volume of the electrolyte returns to the set value, the second three-way valve is opened, and the solid-liquid mixture in the middle and lower parts of the first gas-liquid reaction device and the second gas-liquid reaction device is introduced into the mechanical filter at a set flow rate for filtration.

[0023] Further, the method further comprises the following steps:

[0024] The third three-way valve is opened, the upper electrolyte in the second gas-liquid reaction device is introduced into the multi-medium filter for filtration, and the lower electrolyte in the mechanical filter is delivered to the multi-medium filter at a set flow rate by the fifth centrifugal pump for filtration.

[0025] The electrolyte filtered by the multi-medium filter is delivered to the membrane filter at a set flow rate by the sixth centrifugal pump for filtration, and the electrolyte at the outlet of the membrane filter is sampled and tested, and if the sulfur content in the electrolyte is lower than the set value, the electrolyte is delivered to the positive electrolyte storage tank by the seventh centrifugal pump.

[0026] Further, the method further comprises the following steps:

[0027] The acidic waste gas in the second gas-liquid reaction device is delivered to the third gas-liquid reaction device at a set flow rate by the top gas outlet for first absorption treatment, and the waste gas after the first absorption treatment enters the secondary lye tank through the top gas outlet in the second gas-liquid reaction device for second absorption treatment.

[0028] Further, in the first redox reaction and the second redox reaction, the set flow rate of the electrolyte is 100-300 L / min, and the gas flow rate of the reducing gas is 1.5-3 m 3 / min.

[0029] Further, the method further comprises the following steps:

[0030] Inert gas is delivered into the first gas-liquid reaction device, and the internal pressure of the first gas-liquid reaction device is kept at a set value.

[0031] Advantages of the present application:

[0032] 1、The positive electrolyte in the positive electrolyte storage tank is pumped into the first gas-liquid reaction device and the second gas-liquid reaction device by the first centrifugal pump and the third centrifugal pump to perform redox reaction with the reducing gas, so that the capacity attenuation problem of the acid liquid flow battery electrolyte caused by hydrogen evolution can be well solved, and the operation is simple, economical and friendly to the environment.

[0033] 2、The third gas-liquid reaction device, the primary alkali tank, the secondary alkali tank, the mechanical filter, the multi-medium filter, the membrane filter and the sulfur purification treatment device are arranged, so that waste gas and impurities generated in the electrolyte capacity recovery process can be treated, and by-product elemental sulfur can be obtained, the power plant income is improved, the operation of the whole system is more simple and economical, and the construction and maintenance costs are reduced.

[0034] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure as indicated in the description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0036] Figure 1 A structure schematic diagram of an acid liquid flow battery capacity recovery system according to an embodiment of the present application is shown;

[0037] Figure 2 A main flow schematic diagram of an acid liquid flow battery capacity recovery method according to an embodiment of the present application is shown.

[0038] In the figure: 1, positive electrolyte storage tank; 2, stack; 3, negative electrolyte storage tank; 4, first centrifugal pump; 5, second centrifugal pump; 6, first three-way valve; 7, first gas-liquid reaction device; 8, second gas-liquid reaction device; 9, third gas-liquid reaction device; 10, first alkaline solution tank; 11, second alkaline solution tank; 12, first pipeline; 13, mechanical filter; 14, multi-medium filter; 15, membrane filter; 16, second three-way valve; 17, third three-way valve; 18, second pipeline; 19, third pipeline; 20, valve; 21, third centrifugal pump; 22, fourth centrifugal pump; 23, fifth centrifugal pump; 24, sixth centrifugal pump; 25, seventh centrifugal pump; 26, sulfur purification treatment device. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely explain the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0040] It should be noted that the terms "first", "second", and the like in the present application are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein. In the present application, the terms "up", "down", "left", "right", "front", "back", "top", "bottom", "in", "out", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship shown in the drawings.

[0041] The present application provides a kind of acidic liquid flow battery capacity recovery system and method, it is suitable for the capacity recovery of the electrolyte of large-scale partial capacity reduction acidic system liquid flow battery, simple operation, good economy, can further improve the performance and competitiveness of acidic liquid flow battery, promote its application and development in energy field.

[0042] First, the structure of pickling liquid flow battery is simply explained, as shown in Figure 1 The pickling liquid flow battery includes positive electrolyte storage tank 1, stack 2, negative electrolyte storage tank 3, first centrifugal pump 4 and second centrifugal pump 5.

[0043] The outlet of the positive electrolyte storage tank 1 is connected to the positive electrolyte inlet of the fuel cell stack 2 via a first centrifugal pump 4, and the outlet of the positive electrolyte of the fuel cell stack 2 is connected to the inlet of the positive electrolyte storage tank 1; the outlet of the negative electrolyte storage tank 3 is connected to the negative electrolyte inlet of the fuel cell stack 2 via a second centrifugal pump 5, and the outlet of the negative electrolyte of the fuel cell stack 2 is connected to the inlet of the negative electrolyte storage tank 3.

[0044] like Figure 1 As shown, an acid flow battery capacity recovery system includes a first three-way valve 6, a first gas-liquid reaction device 7, a second gas-liquid reaction device 8, a third gas-liquid reaction device 9, a primary alkali tank 10, a secondary alkali tank 11, a mechanical filter 13, a multi-media filter 14, a membrane filter 15, a second three-way valve 16, a third three-way valve 17, a valve 20, a third centrifugal pump 21, a fourth centrifugal pump 22, a fifth centrifugal pump 23, a sixth centrifugal pump 24, a seventh centrifugal pump 25, and a sulfur purification treatment device 26.

[0045] For example, the first gas-liquid reaction device 7, the second gas-liquid reaction device 8, and the third gas-liquid reaction device 9 can be any one of a bubble column, a spray column, a plate reactor, a packed column, or a bubble stirred tank.

[0046] The first three-way valve 6 is located between the first centrifugal pump 4 and the positive electrolyte inlet of the fuel cell stack 2. The inlet of the first centrifugal pump 4 is connected to the outlet of the positive electrolyte storage tank 1. The a end of the first three-way valve 6 is connected to the outlet of the first centrifugal pump 4. The b end of the first three-way valve 6 is connected to the positive electrolyte inlet of the fuel cell stack 2. The c end of the first three-way valve 6 is connected to the top liquid inlet of the first gas-liquid reaction device 7. The bottom gas inlet of the first gas-liquid reaction device 7 is connected to the reducing gas pipeline and the inert gas pipeline.

[0047] The top air outlet of the first gas-liquid reaction device 7 is connected to the bottom air inlet of the second gas-liquid reaction device 8, the top liquid outlet of the first gas-liquid reaction device 7 is connected to the inlet of the third centrifugal pump 21, and the outlet of the third centrifugal pump 21 is connected to the bottom liquid inlet of the second gas-liquid reaction device 8.

[0048] The top outlet of the second gas-liquid reaction device 8 is connected to the bottom inlet of the third gas-liquid reaction device 9. The top liquid inlet of the third gas-liquid reaction device 9 is connected to the outlet of the fourth centrifugal pump 22. The inlet of the fourth centrifugal pump 22 is connected to the first-stage alkali tank 10. The bottom outlet of the third gas-liquid reaction device 9 is connected to the bottom inlet of the second-stage alkali tank 11. The top outlet of the second-stage alkali tank 11 is connected to the inert gas recovery device.

[0049] The bottom liquid outlet of the first gas-liquid reaction device 7 is communicated with the a end of the second three-way valve 16, the b end of the second three-way valve 16 is communicated with the bottom liquid outlet of the second gas-liquid reaction device 8, the c end of the second three-way valve 16 is communicated with the top liquid inlet of the mechanical filter 13 through the first pipeline 12, the air inlet of the mechanical filter 13 is communicated with the inert gas pipeline, and the air outlet of the mechanical filter 13 is communicated with the inert gas recovery device.

[0050] The sulfur purification treatment device 26 is used for treating the solid after the mechanical filter 13 is subjected to the pressure filtration treatment, so that elemental sulfur is obtained.

[0051] The bottom liquid outlet of the mechanical filter 13 is communicated with the inlet of the fifth centrifugal pump 23, the outlet of the fifth centrifugal pump 23 is communicated with the b end of the third three-way valve 17 through the second pipeline 18, the middle part of the second pipeline 18 is communicated with the first pipeline 12 through the third pipeline 19, and the valve 20 is arranged on the third pipeline 19.

[0052] The top liquid outlet of the second gas-liquid reaction device 8 is communicated with the a end of the third three-way valve 17, the c end of the third three-way valve 17 is communicated with the top liquid inlet of the multi-medium filter 14, the bottom liquid outlet of the multi-medium filter 14 is communicated with the inlet of the sixth centrifugal pump 24, the outlet of the sixth centrifugal pump 24 is communicated with the top liquid inlet of the membrane filter 15, the bottom liquid outlet of the membrane filter 15 is communicated with the inlet of the seventh centrifugal pump 25, and the outlet of the seventh centrifugal pump 25 is communicated with the liquid inlet of the positive electrolyte storage tank 1.

[0053] The multi-medium filter 14 is provided with adsorbents with different particle sizes, and one of the components includes quartz sand, activated carbon, porous ceramic and the like.

[0054] The membrane filter 15 can adopt a PE microporous membrane filter 15, and has the function of filtering out micrometer-level particle impurities, and if necessary, multiple micrometer-level filtrations can be performed.

[0055] The working principle of the acid flow battery capacity recovery system is as follows:

[0056] The charging and discharging process of the flow battery main system is stopped, and the electrolyte in the positive electrolyte storage tank 1 is subjected to capacity recovery offline operation.

[0057] The a end and the c end of the first three-way valve 6 are turned on, the electrolyte in the positive electrolyte storage tank 1 to be recovered is transported to the first gas-liquid reaction device 7 through the first centrifugal pump 4, and the reducing acid gas hydrogen sulfide (the hydrogen sulfide can also be replaced by other reducing gases) is introduced into the first gas-liquid reaction device 7, and the hydrogen sulfide and the ferric chloride are subjected to an oxidation-reduction reaction, and the specific reaction is as follows:

[0058] 16FeCl3+8H2S→16FeCl2+S8↓+16HCl

[0059] The process reduces ferric chloride to ferrous chloride, while simultaneously generating multiple solids, S8 and HCl.

[0060] In the first gas-liquid reaction device 7, the solid product sinks, most of the hydrogen chloride dissolves in the electrolyte, and a portion of the hydrogen chloride gas, along with the unreacted hydrogen sulfide gas, enters the second gas-liquid reaction device 8 from the top outlet of the first gas-liquid reaction device 7, where it continues to undergo the aforementioned redox reaction with the electrolyte from the top of the first gas-liquid reaction device 7.

[0061] The acidic waste gas from the top outlet of the second gas-liquid reaction device 8 contains unreacted hydrogen sulfide gas and a small amount of hydrochloric acid mist. The acidic gas component content is monitored at all times, and the flow rate of the gas path is intelligently adjusted to reduce the escape of hydrogen chloride gas. The gas is then introduced into the third gas-liquid reaction device 9. The first gas-liquid reaction device 7 is connected to the primary alkaline tank 10 (which can also be replaced with a copper sulfate solution of a certain concentration) through a pipeline. The acidic waste gas is absorbed by spraying. If necessary, a secondary alkaline tank 11 can be set up for secondary absorption.

[0062] Opening the second three-way valve 16, the lower layer of the first gas-liquid reaction device 7 and the second gas-liquid reaction device 8 contains solid S8 and / or other S. x The suspension enters the mechanical filter 13 for the first pressure filtration treatment, in which inert gas is introduced and pressurized to 0.5-1 MPa. The fifth centrifugal pump 23 and valve 20 are turned on, and the filtrate after the first pressure filtration treatment re-enters the mechanical filter 13 for a second pressure filtration.

[0063] Close valve 20 and open the third three-way valve 17 to allow the filtrate after the secondary pressure filtration treatment and the upper clear liquid of the second gas-liquid reaction device 8 to enter the multi-media filter 14 for filtration treatment.

[0064] The filtrate filtered by the multi-media filter 14 is transported to the membrane filter 15 by the sixth centrifugal pump 24 for further filtration. The filtrate after filtration by the membrane filter 15 is sampled for relevant ion concentration detection. If the electrolyte sample capacity recovery rate reaches more than 95%, the hydrochloric acid concentration meets the initial concentration requirements, and the particulate impurity content is less than 1‰, it can be transported to the positive electrode electrolyte storage tank 1 by the seventh centrifugal pump 25 for normal cycle charging and discharging.

[0065] Based on the above-mentioned capacity recovery system for acidic flow batteries, such as Figure 2 As shown, the present invention also provides a method for restoring the capacity of an acidic flow battery, comprising the following steps:

[0066] S1. Determine the electrolyte capacity of the flow battery. If the electrolyte capacity is lower than the set value, determine to restore the positive electrolyte capacity in the positive electrolyte storage tank 1.

[0067] For example, when the electrolyte capacity of a flow battery decays to 60% or less of its original capacity, a capacity recovery operation is prepared for the electrolyte. Specifically, this includes: after a certain deep discharge cycle is completed, opening the positive electrode sampling valve 20, performing a titration test on the sample electrolyte, and observing the concentrations of ferrous ions and ferric ions. If the amount of ferric ions accounts for 60% or more of the total iron concentration, then it is determined that the capacity of the positive electrode electrolyte in the positive electrode electrolyte storage tank 1 will be restored.

[0068] S2. Stop the main system PCS equipment and perform offline operation on the electrolyte. At this time, the electrolyte temperature is the reaction temperature during charging and discharging, which is generally 50-65℃. In order to improve the gas-liquid reaction efficiency, the electrolyte temperature can be lowered to 20-30℃.

[0069] S3. Open the first three-way valve 6, and use the first centrifugal pump 4 to deliver the electrolyte in the positive electrolyte storage tank 1 to the first gas-liquid reaction device 7 at a set flow rate. At the same time, hydrogen sulfide (which can also be replaced by other reducing gases) is delivered into the first gas-liquid reaction device 7 to cause the hydrogen sulfide to undergo the first oxidation-reduction reaction with the ferric chloride in the electrolyte. By delivering inert gas into the first gas-liquid reaction device 7, the internal pressure of the first gas-liquid reaction device 7 is maintained at a set value. This step can prevent the reaction equipment from causing other negative effects under low pressure conditions.

[0070] For example, to ensure a complete gas-liquid reaction, the electrolyte flow rate is set to 100-300 L / min in the first oxidation-reduction reaction, preferably 200 L / min. The flow rate is controlled by adjusting the pump frequency according to the type and model of the first centrifugal pump 4 used.

[0071] For example, in the first redox reaction, the purity of the reducing gas (hydrogen sulfide) is required to be 99.999% or higher, and the gas flow rate of the reducing gas (hydrogen sulfide) is controlled at 1.5–3 m / s. 3 The flow rate of the reducing gas (hydrogen sulfide) is preferably controlled at 2–2.5 m / min. 3 / min; Due to the negative pressure caused by the gas-liquid reaction, the internal pressure of the first gas-liquid reaction device 7 is automatically monitored to see if it is within the set value (0.3MPa~0.5MPa), and the internal pressure of the first gas-liquid reaction device 7 is regulated by introducing inert gas.

[0072] S4. The electrolyte after the first oxidation-reduction reaction in the first gas-liquid reaction device 7 is transported to the second gas-liquid reaction device 8 through the third centrifugal pump 21. At the same time, the gas after the reaction in the first gas-liquid reaction device 7 enters from the bottom of the second gas-liquid reaction device 8 and undergoes a second oxidation-reduction reaction with the electrolyte after the first oxidation-reduction reaction. The process parameters of the second oxidation-reduction reaction are the same as those of the first oxidation-reduction reaction.

[0073] S5. After the second redox reaction, determine whether the electrolyte capacity has recovered to the set value, as follows:

[0074] Take an electrolyte sample and test the concentrations of ferrous iron and total iron. Determine whether the electrolyte capacity has recovered to the set value based on the concentrations of ferrous iron and total iron. The capacity recovery rate of the electrolyte can be achieved at over 95% through steps S3 and S4. If the recovery rate needs to be adjusted, it can be achieved by increasing / decreasing the number of redox reaction cycles.

[0075] S6. Once the electrolyte capacity is determined to have returned to the set value, open the second three-way valve 16 to introduce the solid-liquid mixture from the lower part of the first gas-liquid reaction device 7 and the second gas-liquid reaction device 8 into the mechanical filter 13 for filtration at a set flow rate, and introduce inert gas to maintain the internal pressure of the mechanical filter 13 at the set value.

[0076] For example, the flow rate of the solid-liquid mixture is controlled at 100-200 L / min, preferably 100 L / min, and the internal pressure of the mechanical filter 13 is maintained at 0.5-1 MPa, preferably 0.5 MPa.

[0077] S7. Set a time interval to clean the filter cake of the mechanical filter 13, and send the filter cake to the sulfur purification treatment device 26 for processing to obtain elemental sulfur, or it can be further processed to obtain sulfur-containing chemicals such as sulfuric acid.

[0078] S8. Open the third three-way valve 17. The upper electrolyte in the second gas-liquid reaction device 8 is introduced into the multi-media filter 14 for filtration. The lower electrolyte of the mechanical filter 13 is transported to the multi-media filter 14 for filtration at a set flow rate by the fifth centrifugal pump 23.

[0079] For example, the flow rate of the lower electrolyte delivered by the fifth centrifugal pump 23 to the multi-media filter 14 is controlled at 100-200 L / min, preferably 100 L / min. The outlet flow rate of the multi-media filter 14 is monitored. When the outlet flow rate of the multi-media filter 14 is less than 50% of the inlet flow rate, the filter media in the multi-media filter 14 is replaced.

[0080] S9. The sulfur content in the electrolyte sample at the outlet of the multi-media filter 14 is tested. At this time, the sulfur content is less than 0.5 wt.%.

[0081] S10. The electrolyte filtered by the multi-media filter 14 is transported to the membrane filter 15 for filtration by the sixth centrifugal pump 24 at a set flow rate. The electrolyte at the outlet of the membrane filter 15 is sampled and tested. If the sulfur content in the electrolyte is lower than the set value, the electrolyte is transported to the positive electrode electrolyte storage tank 1 by the seventh centrifugal pump 25.

[0082] For example, the flow rate of electrolyte delivered by the sixth centrifugal pump 24 to the membrane filter 15 is controlled at 100-200 L / min, preferably 100 L / min. The membrane filter 15 can remove micron-sized sulfur solid particles. When the sample from the outlet of the membrane filter 15 is sampled and tested, the sulfur content is less than 0.8 wt.‰, which meets the usage index. It can then be pumped into the positive electrode electrolyte storage tank 1, and the heat exchanger heats it to the reaction temperature for normal charge and discharge reaction.

[0083] S11, the acidic waste gas in the second gas-liquid reaction device 8 is transported to the third gas-liquid reaction device 9 at a set flow rate through the top outlet for the first absorption treatment. The waste gas after the first absorption treatment enters the secondary alkaline tank 11 through the top outlet in the second gas-liquid reaction device 8 for the second absorption treatment, and the inert gas is discharged.

[0084] The acidic waste gas discharged from the upper part of the second gas-liquid reaction device 8 includes unreacted hydrogen sulfide gas, inert gas used for pressure regulation, and hydrogen chloride gas carried out by the two. The content of acidic gas components is monitored at any time, and the flow rate of the gas path is intelligently adjusted to reduce the escape of hydrogen chloride gas. It is then passed into the third gas-liquid reaction device 9 at a flow rate of 200-500 L / min for absorption, and then passed into the secondary alkaline tank 11 for secondary absorption. The inert gas is discharged, completing the treatment of the waste gas.

[0085] This invention proposes a system and method for restoring the capacity of an acidic flow battery. It can restore the capacity of 300 cubic meters of electrolyte that has decayed to 60% to over 95% within 3 days. The initial investment is about 300,000 yuan, and the cost of each restoration can be controlled within 100,000 yuan. If a new electrolyte is required to achieve the same level of capacity restoration, the amortized cost per restoration reaches 1.5 million yuan. This process is highly adjustable, simple, fast, and has high reaction efficiency. It can also obtain elemental sulfur as a byproduct, thereby increasing the power plant's revenue and making it highly economical.

[0086] The present invention proposes a system and method for restoring the capacity of acidic flow batteries, which can effectively solve the capacity decay problem caused by hydrogen evolution in the electrolyte of acidic flow batteries. It is simple to operate, economical, and environmentally friendly, providing a new solution to the problem of electrolyte capacity decay in acidic flow batteries and providing strong support for the further development and application of acidic flow battery technology.

[0087] The acidic flow battery capacity recovery system and method of this invention can effectively restore electrolyte capacity, treat generated waste gas and impurities, and obtain elemental sulfur as a byproduct, thereby increasing power plant revenue. This simplifies and economically improves the operation of the entire system, reducing construction and maintenance costs. In practical applications, the electrolyte capacity recovery method of this invention can be widely used in large-scale acidic flow battery systems with partially reduced capacity. By periodically or as needed restoring the electrolyte capacity, the service life of the battery system can be effectively extended, and the system's stability and reliability can be improved.

[0088] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for recovery of capacity of an acidic flow battery, characterized in that, The system comprises a first centrifugal pump, a first three-way valve, a first gas-liquid reaction device, a second gas-liquid reaction device and a third centrifugal pump. The inlet of the first centrifugal pump is communicated with the outlet of the positive electrolyte storage tank, the a end of the first three-way valve is communicated with the outlet of the first centrifugal pump, the b end of the first three-way valve is communicated with the positive electrolyte inlet of the stack, the c end of the first three-way valve is communicated with the top liquid inlet of the first gas-liquid reaction device, and the bottom gas inlet of the first gas-liquid reaction device is communicated with the reducing gas pipeline and the inert gas pipeline. The top gas outlet of the first gas-liquid reaction device is communicated with the bottom gas inlet of the second gas-liquid reaction device, the top liquid outlet of the first gas-liquid reaction device is communicated with the inlet of the third centrifugal pump, and the outlet of the third centrifugal pump is communicated with the bottom liquid inlet of the second gas-liquid reaction device.

2. The acidic flow battery capacity recovery system of claim 1, wherein, The system further comprises a third gas-liquid reaction device, a primary alkali liquid tank, a secondary alkali liquid tank and a fourth centrifugal pump. The top gas outlet of the second gas-liquid reaction device is communicated with the bottom gas inlet of the third gas-liquid reaction device, the top liquid inlet of the third gas-liquid reaction device is communicated with the outlet of the fourth centrifugal pump, the inlet of the fourth centrifugal pump is communicated with the primary alkali liquid tank, the bottom gas outlet of the third gas-liquid reaction device is communicated with the bottom gas inlet of the secondary alkali liquid tank, and the top gas outlet of the secondary alkali liquid tank is communicated with the inert gas recovery device.

3. The acidic flow battery capacity recovery system of claim 1, wherein, The system further comprises a mechanical filter and a second three-way valve. The bottom liquid outlet of the first gas-liquid reaction device is communicated with the a end of the second three-way valve, the b end of the second three-way valve is communicated with the bottom liquid outlet of the second gas-liquid reaction device, the c end of the second three-way valve is communicated with the top liquid inlet of the mechanical filter through a first pipeline, the gas inlet of the mechanical filter is communicated with the inert gas pipeline, and the gas outlet of the mechanical filter is communicated with the inert gas recovery device.

4. The acidic flow battery capacity recovery system of claim 3, wherein, The system further comprises a multi-medium filter, a membrane filter, a third three-way valve and a sixth centrifugal pump. The top liquid outlet of the second gas-liquid reaction device is communicated with the a end of the third three-way valve, the c end of the third three-way valve is communicated with the top liquid inlet of the multi-medium filter, the bottom liquid outlet of the multi-medium filter is communicated with the inlet of the sixth centrifugal pump, and the outlet of the sixth centrifugal pump is communicated with the top liquid inlet of the membrane filter.

5. The acidic flow battery capacity recovery system of claim 4, wherein, The system further comprises a fifth centrifugal pump, the bottom liquid outlet of the mechanical filter is communicated with the inlet of the fifth centrifugal pump, the outlet of the fifth centrifugal pump is communicated with the b end of the third three-way valve through a second pipeline, the second pipeline is communicated with the first pipeline through a third pipeline, and a valve is arranged on the third pipeline.

6. The acidic flow battery capacity recovery system of claim 4, wherein, The system further comprises a seventh centrifugal pump, the bottom liquid outlet of the membrane filter is communicated with the inlet of the seventh centrifugal pump, and the outlet of the seventh centrifugal pump is communicated with the liquid inlet of the positive electrolyte storage tank.

7. The acidic flow battery capacity recovery system of any one of claims 3-6, wherein, The system further comprises a sulfur purification treatment device, which is used for treating the solid after the mechanical filter is pressed and filtered to obtain elemental sulfur.

8. A method of recovering the capacity of an acidic flow battery, characterized by, The system for recovering the capacity of an acidic flow battery according to any one of claims 1-7 is implemented, comprising the following steps: The first three-way valve is opened, and the electrolyte in the positive electrolyte storage tank is delivered to the first gas-liquid reaction device at a set flow rate by the first centrifugal pump, and a reducing gas is delivered to the first gas-liquid reaction device, so that the reducing gas and the ferric chloride in the electrolyte are subjected to a first redox reaction; The electrolyte after the first redox reaction in the first gas-liquid reaction device is delivered to the second gas-liquid reaction device by the third centrifugal pump, and the gas after the reaction in the first gas-liquid reaction device enters the second gas-liquid reaction device from the bottom of the second gas-liquid reaction device, and is subjected to a second redox reaction with the electrolyte after the first redox reaction.

9. The method of recovering the capacity of an acidic flow battery according to claim 8, wherein, The following steps are further included: When it is determined that the capacity of the electrolyte is restored to the set value, the second three-way valve is opened, and the solid-liquid mixture in the middle and lower parts of the first gas-liquid reaction device and the second gas-liquid reaction device is introduced into the mechanical filter at a set flow rate for filtration.

10. The method of recovering the capacity of an acidic flow battery according to claim 9, wherein, The following steps are further included: The third three-way valve is opened, the upper electrolyte in the second gas-liquid reaction device is introduced into the multi-medium filter for filtration, and the lower electrolyte of the mechanical filter is delivered to the multi-medium filter at a set flow rate by the fifth centrifugal pump for filtration; The electrolyte filtered by the multi-medium filter is delivered to the membrane filter at a set flow rate by the sixth centrifugal pump for filtration, and the electrolyte at the outlet of the membrane filter is sampled and tested, and if the sulfur content in the electrolyte is lower than the set value, the electrolyte is delivered to the positive electrolyte storage tank by the seventh centrifugal pump.

11. The method of recovering the capacity of an acidic flow battery according to claim 10, wherein, The following steps are further included: The acidic waste gas in the second gas-liquid reaction device is delivered to the third gas-liquid reaction device at a set flow rate by the top gas outlet for first absorption treatment, and the waste gas after the first absorption treatment enters the secondary lye tank through the top gas outlet in the second gas-liquid reaction device for second absorption treatment.

12. The method of recovering capacity of an acidic flow battery according to any one of claims 8-11, wherein, In the first and second redox reactions, the electrolyte is set to a flow rate of 100 to 300 L / min, and the reducing gas is set to a gas flow rate of 1.5 to 3 m 3 / min.

13. The method of recovering the capacity of an acidic flow battery according to claim 8, wherein, The following steps are further included: An inert gas is delivered to the first gas-liquid reaction device, so that the internal pressure of the first gas-liquid reaction device is maintained at a set value.

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