A method for treating VOCs in the production of battery negative materials in a tunnel kiln

Abstract

The application discloses a VOC treatment method in the process of producing battery negative material in a tunnel kiln, belongs to the technical field of VOC treatment of the tunnel kiln, and is characterized in that a VOC collecting device is arranged in a heating section to capture high-concentration VOC waste gas; the waste gas is transported to a first water spray tower and a second alkali washing tower through a fan via a ceramic anticorrosive layer pipeline; the first water spray tower removes large-particle dust, part of water-soluble organic matters and cools to less than or equal to 80 DEG C; the second alkali washing tower removes acid gases and tar substances by spraying 5-10% NaOH solution; the pretreated waste gas enters a catalytic combustion unit, is diluted in VOC concentration by a blast box, is preheated in turn by a plate heat exchanger, is heated by a natural gas burner, is decomposed in VOC in a catalyst fixed bed, and high-temperature purified gas is discharged after waste heat recovery; and the purified gas is introduced into a chimney by an induced draft fan and is discharged. Through the combined process of "collection + spraying + catalytic combustion", the total VOC removal rate of the process is greater than or equal to 98%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel kiln VOC treatment, and relates to a VOC treatment method in the process of producing battery negative materials in a tunnel kiln. BACKGROUND

[0002] Under the background of explosive growth of the lithium ion battery industry, as the core equipment for producing artificial graphite, mesocarbon microbeads and other negative materials, the high-temperature carbonization process (≥1000℃) of the tunnel kiln is widely used in the new energy automobile and energy storage fields. In the production of negative materials, organic precursors such as petroleum coke and pitch coke undergo the stages of heating, high-temperature carbonization and cooling in the tunnel kiln, and are converted into carbon materials with a layered structure.

[0003] However, with the expansion of the industry, environmental compliance has become a key problem restricting the development of enterprises. In particular, in the heating section (200-800℃) of the feed end, a large amount of light components (such as benzene series and polycyclic aromatic hydrocarbons) in the organic precursors are volatilized, forming high-concentration VOC waste gas. According to statistics, about 3-5 kg of VOC is generated per ton of negative material produced. These VOC components are complex and some are strongly carcinogenic, and their emissions will exacerbate environmental problems such as photochemical smog and ozone pollution, posing a serious threat to the ecological environment and human health.

[0004] At present, the industry generally uses the method of “direct discharge + simple water washing” to treat VOC waste gas, but this method has poor effect and the removal rate of VOC is less than 15%. Direct discharge of waste gas without effective treatment not only causes serious air pollution, but also makes enterprises face high environmental penalties and the risk of production suspension. In addition, components such as tar and dust contained in VOC are easily attached to the inner wall of the pipeline during the discharge process, causing pipeline blockage, and also have a corrosive effect on the equipment, increasing the operation and maintenance cost of the equipment and affecting the normal production and economic benefits of enterprises. SUMMARY

[0005] The purpose of the present application is to provide a VOC treatment method in the process of producing battery negative materials in a tunnel kiln, which realizes efficient removal of high-concentration and complex-component VOC waste gas in the heating section of the tunnel kiln by constructing an integrated process of “collection-two-stage spray pretreatment-catalytic combustion”.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A VOC treatment method in the process of producing battery negative materials in a tunnel kiln, comprising the following steps:

[0008] Step 1: A plurality of gas inlet pipes are distributed in the heating section of the tunnel kiln, the gas inlet pipes are connected to the inlet of the fan after being collected into a gas inlet main pipe, and a gas inlet adjusting valve is arranged on each gas inlet pipe to capture high-concentration VOC waste gas volatilized by the material;

[0009] Step 2, the collected exhaust gas is transported by the fan through the pipeline lined with ceramic anticorrosive layer to a two-stage spray tower pretreatment system, which is composed of a first-stage water spray tower and a second-stage alkali washing tower, the first-stage water spray tower removes large-particle dust and part of water-soluble organic matter by circulating water spraying, while reducing the temperature to ≤80℃, the spraying density is 30-50 m³ / (m²·h), and the exhaust gas residence time is 5-15 s; the second-stage alkali washing tower removes acid gases and tar substances by spraying 5-10% NaOH solution, the spraying density is 35-50 m³ / (m²·h), and the exhaust gas residence time is 10-20 s, and a mud scraper is arranged at the bottom of the second-stage alkali washing tower for periodically discharging tar residues;

[0010] Step 3, the pretreated exhaust gas enters a catalytic combustion unit, the catalytic combustion unit includes a box body, a mixing box is arranged at the air inlet of the box body, and the mixing box is used for diluting the VOC concentration in the exhaust gas to below 25% of the lower explosive limit; a plate heat exchanger, a natural gas burner and a catalyst fixed bed are arranged in the box body, the diluted exhaust gas is preheated to 200-250℃ by the plate heat exchanger, and then heated to the catalyst activation temperature of 300-350℃ by the natural gas burner, the catalyst on the catalyst fixed bed decomposes VOC into CO2 and H2O, the reaction heat makes the temperature rise to 400-450℃ to form high-temperature purified gas, and the high-temperature purified gas is discharged from the discharge port of the box body after recovering waste heat by the plate heat exchanger;

[0011] Step 4, the purified gas discharged from the discharge port of the box body is introduced into a chimney by an induced draft fan and discharged.

[0012] In the method, the exhaust gas flow, temperature and concentration parameters are monitored in real time by PLC integrated control, and the spraying amount and heating power are automatically adjusted.

[0013] As a further improvement of an embodiment of the application, an explosion-proof valve is arranged on the pipeline between the air outlet of the fan and the air inlet of the first-stage water spray tower in step 2.

[0014] As a further improvement of an embodiment of the application, the first-stage water spray tower in step 2 includes a water washing cylinder, a first spray disc, a first filler layer and a first demister are arranged in the water washing cylinder, a water washing circulating pump is arranged outside the water washing cylinder, the inlet of the water washing circulating pump is connected with the lower end of the water washing cylinder through a first pipeline, a first switch valve is arranged on the first pipeline, the outlet of the water washing circulating pump is connected with the first spray disc through a second pipeline, a first flow valve is arranged on the second pipeline, and the first switch valve and the first flow valve are linked and controlled.

[0015] As a further improvement of the embodiment of the present application, the secondary alkali washing tower in step 2 comprises an alkali washing cylinder, the alkali washing cylinder is provided with a second spray tray, a second filler layer and a second demister, the alkali washing cylinder is externally provided with an alkali liquor circulating pump, the inlet of the alkali liquor circulating pump is connected with the lower end of the alkali washing cylinder through a third pipeline, the third pipeline is provided with a second switch valve, the outlet of the alkali liquor circulating pump is connected with the second spray tray through a fourth pipeline, the fourth pipeline is provided with a second flow valve, and the second flow valve is linked and controlled with the second switch valve.

[0016] As a further improvement of the embodiment of the present application, the natural gas burner in step 3 is connected with a natural gas system and an oxygen supplement system respectively, the natural gas system comprises a natural gas pipeline, and the pipeline is sequentially provided with a filter, a check valve, a pressure transmitter and a pressure gauge; the oxygen supplement system comprises an oxygen pipeline, and the pipeline is sequentially provided with an electric pump, an expansion joint and a filter.

[0017] As a further improvement of the embodiment of the present application, the catalyst in step 3 is a supported noble metal catalyst with Pt / Pd as the active component.

[0018] A system for implementing the above method comprises a VOC collecting device, a fan, a two-stage spray tower pretreatment system, a catalytic combustion unit and an induced draft fan connected in sequence, the box of the catalytic combustion unit is provided with a mixed air box, a plate heat exchanger, a natural gas burner and a catalyst fixed bed, and the system is integrated controlled by a PLC controller.

[0019] The above technical solution has the following beneficial effects: 1. Through the combined process of "collection + spraying + catalytic combustion", the total removal rate of VOC is ≥98%, and the emission concentration is <50mg / m³, which is much lower than the national standard; 2. The spray tower pretreatment effectively removes tar and dust, avoids catalyst poisoning, and prolongs the service life of the equipment by 3-5 years; 3. The catalytic combustion waste heat recovery system can save more than 70% of heating energy, and the comprehensive operation cost is reduced by 30%; 4. The system has strong compatibility, does not need to modify the structure of the existing tunnel kiln, only needs to add a treatment unit outside the kiln body, and does not interfere with the production process. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in 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 only exemplary, and those skilled in the art can also obtain other implementation drawings according to the provided drawings without creating any creative labor.

[0021] The structures, proportions, sizes, etc. shown in the specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the conditions that can be implemented by the application, so they do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the application, should still fall within the scope covered by the disclosed technology.

[0022] Figure 1 The tunnel kiln structure provided by the application is shown in the schematic diagram.

[0023] Figure 2 The flowchart provided by the application is shown in the schematic diagram.

[0024] Figure 3 The two-stage spray tower pretreatment system and catalytic combustion unit combination provided by the application is shown in the schematic diagram. DETAILED DESCRIPTION

[0025] In the present application, the orientation words such as "up, down, top, bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity direction of the components themselves; similarly, for the convenience of understanding and description, "inner, outer" refers to the inner and outer relative to the contour of each component itself, but the above orientation words are not used to limit the present application.

[0026] First embodiment

[0027] As shown in Figure 2 , 3 , the tunnel kiln is composed of a heating section 1, a high-temperature section 2 and a cooling section 3, wherein a gas curtain fan 4 is arranged at the front end of the tunnel kiln, and a high-speed flowing "air barrier" (gas curtain) is generated to realize isolation, sealing and airflow control in the tunnel kiln entrance area. The present application realizes efficient removal of high-concentration, complex-component VOC waste gas generated in the heating section 1 of the tunnel kiln, and the specific method is as follows:

[0028] In combination with Figure 1 , a VOC treatment method in the production of battery negative material by tunnel kiln includes the following steps:

[0029] Step 1, set VOC collection device at the heating section of the tunnel kiln to capture high-concentration VOC waste gas volatilized by the material. Specifically, the VOC collection device includes a plurality of gas inlet pipes 5-15 distributed on the heating section 1, and the number of gas inlet pipes can be flexibly adjusted according to the actual size of the tunnel kiln, the concentration and total amount of VOC volatilized by the material, and other factors. Each gas inlet pipe is correspondingly provided with a gas inlet adjusting valve 16-26, and the gas inlet amount of each gas inlet pipe can be accurately controlled by adjusting the opening degree of the gas inlet adjusting valve, so as to flexibly control the VOC collection amount of different regions and ensure that the high-concentration VOC waste gas is fully captured.

[0030] Step 2, after the gas inlet pipes 5-15 are collected into the gas inlet main pipe 27, the inlet of the fan 28 is connected, and the fan 28 is connected to the two-stage spray tower pretreatment system through the pipeline. In order to improve the overall corrosion resistance of the pipeline, all pipelines such as the gas inlet pipes 5-15 and the gas inlet main pipe 27 are made of ceramic anticorrosion lining pipes. This kind of pipe structure not only can effectively resist the corrosion of corrosive substances in VOC waste gas, prolong the service life of the pipeline, but also can reduce the risk of waste gas leakage.

[0031] The two-stage spray tower pretreatment system in the present scheme is composed of a first-stage water spray tower 30 and a second-stage alkali washing tower 35. The first-stage water spray tower 30 sprays water to separate large-particle dust and part of water-soluble organic matter from the waste gas by physical adsorption and dissolution, and at the same time, the temperature of the waste gas is reduced to ≤80℃, the spray density is 30-50m³ / (m²·h), and the waste gas residence time is 5-15s, which creates good conditions for subsequent treatment. The second-stage alkali washing tower 35 sprays 5-10% NaOH solution, the spray density is 35-50m³ / (m²·h), the waste gas residence time is 10-20s, and the NaOH solution reacts with acidic gases and tar substances in the waste gas to achieve effective removal. The mud scraper at the bottom can be operated regularly to discharge the precipitated tar residue out of the tower, ensuring the normal operation of the second-stage alkali washing tower.

[0032] In addition, the explosion-proof valve 29 arranged on the pipeline between the outlet of the fan 28 and the inlet of the first-stage water spray tower 30 can timely block the flame propagation in case of explosion and other accidents, ensuring the safe and stable operation of the whole system.

[0033] Step 3, the pretreated waste gas enters the catalytic combustion unit, which includes a box body 40, and a mixed air box 41 is arranged at the air inlet of the box body 40. The mixed air box 41 can dilute the VOC concentration in the waste gas to below 25% of the lower explosive limit by introducing fresh air and the like, so as to ensure the safety of the subsequent treatment process.

[0034] The box 40 is provided with a plate heat exchanger 42, a natural gas burner 48 and a catalyst fixed bed 43. The plate heat exchanger 42 uses the waste heat after reaction to preheat the diluted exhaust gas to a temperature of 200-250℃. Then, the natural gas burner 48 further heats the exhaust gas to a temperature of 300-350℃, which is the activation temperature of the catalyst. At this time, the exhaust gas enters the catalyst fixed bed 43, and under the action of the catalyst, the VOC in the exhaust gas is efficiently decomposed into CO2 and H2O. The reaction heat released during the reaction process will raise the temperature to 400-450℃, forming high-temperature purified gas. The high-temperature purified gas is then recycled by the plate heat exchanger 42 to reduce energy consumption, and finally discharged from the discharge port of the box 40.

[0035] In this scheme, the catalyst is a supported noble metal catalyst with Pt / Pd as the active component. The support carrier can be selected from materials with large specific surface area and stable chemical properties, such as alumina and silicon dioxide. This catalyst can effectively promote the decomposition of VOC in the exhaust gas and has good activity and stability.

[0036] Step 4, the purified gas discharged from the discharge port of the box 40 is smoothly introduced into the chimney 47 under the action of the induced draft fan 46, and finally safely discharged into the atmosphere through the chimney 47;

[0037] The above-mentioned VOC treatment method can monitor the flow, temperature and concentration parameters of the exhaust gas in real time through PLC integrated control, and automatically adjust the spraying amount and heating power.

[0038] As shown in Figure 3 As shown in FIG. 1, the first-stage water spray tower 30 includes a water washing cylinder 301, and the top of the water washing cylinder 301 is provided with a gas discharge port for discharging treated gas. The water washing cylinder 301 is provided with a first spray disc 302, a first filler layer 303 and a first mist eliminator 32. The first spray disc 302 and the first filler layer 303 are provided in two groups, and the first mist eliminator 32 is located above the first spray disc 302 and the first filler layer 303. Such a layout can ensure that the gas is treated by spraying, filtering and demisting in sequence.

[0039] The water washing cylinder 301 is provided with a process water interface A33 and a water washing sewage outlet 315. The process water interface A33 is used to access the process water required for processing, and the water washing sewage outlet 315 is used to discharge the sewage generated in the processing process. The water washing cylinder 301 is externally provided with a water washing circulating pump 31. The inlet of the water washing circulating pump 31 is connected to the lower end of the water washing cylinder 301 through a first pipeline 311. The first pipeline 311 is provided with a first on-off valve 312, which can control the on-off of the water flow. The outlet of the water washing circulating pump 31 is connected to the first spraying disc 302 through a second pipeline 313. The second pipeline 313 is provided with a first flow valve 314, which is used to adjust the spraying water amount. The first on-off valve 312 and the first flow valve 314 are controlled by PLC linkage, which can accurately adjust the spraying water amount and start-stop according to the actual processing situation, and ensure the processing effect.

[0040] The secondary alkaline washing tower 35 includes an alkaline washing cylinder 351. The top of the alkaline washing cylinder 351 is an exhaust port, which is used to discharge the purified gas. The alkaline washing cylinder 351 is provided with a second spraying disc 352, a second filler layer 353 and a second demister 37. The second spraying disc 352 and the second filler layer 353 have two groups, and the second demister 37 is located above the second spraying disc 352 and the second filler layer 353. Such a structure can ensure that the gas passes through the spraying alkali solution, the filler layer for full contact reaction and the demisting treatment in sequence.

[0041] The alkaline washing cylinder 351 is provided with a process water interface B38, an alkali solution inlet 39 and an alkaline washing sewage outlet 354. The process water interface B38 can access the process water when necessary. The alkali solution inlet 39 is used to introduce 5-10% NaOH solution and other alkali solutions. The alkaline washing sewage outlet 354 is used to discharge the waste liquid after reaction. The alkaline washing cylinder 351 is externally provided with an alkali solution circulating pump 36. The inlet of the alkali solution circulating pump 36 is connected to the lower end of the alkaline washing cylinder 351 through a third pipeline 355. The third pipeline 355 is provided with a second on-off valve 356 to control the on-off of the alkali solution. The outlet of the alkali solution circulating pump 36 is connected to the second spraying disc 352 through a fourth pipeline 357. The fourth pipeline 357 is provided with a second flow valve 358 to adjust the flow of the alkali solution. The second flow valve 358 and the second on-off valve 356 are controlled by PLC linkage to ensure the stable circulation of the alkali solution.

[0042] In addition, the water washing sewage outlet 315 and the alkaline washing sewage outlet 354 share a sewage pipeline 34, which is convenient for unified treatment of waste liquid.

[0043] The natural gas burner in step 3 is connected with a natural gas system 44 and an oxygen supplement system 45 respectively. Specifically, the natural gas system 44 mainly comprises a natural gas pipeline connected with a natural gas source. A filter is arranged on the natural gas pipeline in sequence according to the gas flow direction, which functions to filter out impurities in the natural gas to prevent damage to subsequent equipment; a check valve can prevent gas backflow to ensure safe operation of the system; a pressure transmitter can monitor the pressure of the natural gas in the pipeline in real time and transmit the pressure signal to the PLC control system; and a pressure gauge can directly display the natural gas pressure value, facilitating observation by the operator.

[0044] The oxygen supplement system 45 comprises an oxygen pipeline connected with an oxygen source. An electric pump is arranged on the oxygen pipeline in sequence, which provides power for oxygen delivery; an expansion joint can compensate for thermal expansion and contraction of the oxygen pipeline due to factors such as temperature changes to prevent pipeline damage; and a filter is used to filter out small particles in the oxygen to ensure that the oxygen entering the natural gas burner is pure.

[0045] The above design ensures stable and efficient combustion process and ensures heating of the waste gas to the catalyst activation temperature.

[0046] The present application relies on advanced PLC integrated control technology for VOC waste gas treatment and builds an intelligent operation and management system. The system can monitor key parameters such as waste gas flow, temperature and concentration in real time and accurately. By installing high-precision flow sensors, temperature sensors and concentration detectors at key positions, the collected data is fed back to the PLC control system in real time. Based on these data, the system can automatically adjust the operating parameters of each processing unit, such as adjusting the spraying amount of the spraying tower according to the waste gas flow, controlling the heating power of the natural gas burner according to the waste gas temperature, etc., to ensure the treatment efficiency and the stability of the system operation, effectively reduce the cost of manual intervention, and reduce the risk caused by human operation errors.

[0047] A system for implementing the above-mentioned VOC waste gas treatment method comprises a VOC collection device, a fan, a two-stage spraying tower pretreatment system, a catalytic combustion unit and an induced draft fan connected in sequence, and a mixing box, a plate heat exchanger, a natural gas burner and a catalyst fixed bed are arranged in the box of the catalytic combustion unit, and the system is integrated controlled by a PLC controller.

[0048] The application has significant treatment effect through the combination process of "collection + spraying + catalytic combustion". Through actual detection, the total removal rate of VOC can reach ≥98%, and the emission concentration is <50mg / m³, which is much lower than the requirements of the relevant national standards. The spraying tower pretreatment link can efficiently remove impurities such as tar and dust in the waste gas, prevent the impurities from entering the catalytic combustion unit to cause catalyst poisoning, and thus prolong the service life of the equipment by 3-5 years. The catalytic combustion waste heat recovery system can recycle the waste heat generated in the reaction, save more than 70% of the heating energy consumption, and reduce the comprehensive operation cost by 30%. In addition, the system has strong compatibility, does not need to make large-scale structural modification to the existing tunnel kiln, only needs to reasonably add a treatment unit outside the kiln body, does not interfere with the normal production process, and is convenient for popularization and application.

[0049] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0050] It should be noted that the terms "first", "second", and the like, as used in the specification and in the claims, are intended to modify a particular aspect of the subject matter described and are not intended to "limit" the aspect according to the specific sequence, unless otherwise indicated by the context.

[0051] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for VOC treatment in the production of battery anode material in a tunnel kiln, characterized in that, The method comprises the following steps: Step 1: A plurality of air inlets are distributed in the heating section of the tunnel kiln, and the air inlets are connected to the inlet of the fan after being gathered into an air inlet main pipe; an air inlet adjusting valve is arranged on each air inlet to capture high-concentration VOC waste gas volatilized from the material; Step 2: The collected waste gas is transported by the fan to a two-stage spray tower pretreatment system through a pipeline lined with a ceramic anticorrosive layer, the two-stage spray tower pretreatment system is composed of a first-stage water spray tower and a second-stage alkali washing tower, the first-stage water spray tower removes large-particle dust and part of water-soluble organic matter through water spray circulation, and the temperature is reduced to ≤80℃, the spray density is 30-50 m³ / (m²·h), and the waste gas residence time is 5-15 s; the second-stage alkali washing tower uses 5-10% NaOH solution for spray, removes acid gas and tar substances, the spray density is 35-50 m³ / (m²·h), the waste gas residence time is 10-20 s, and a mud scraper is arranged at the bottom of the second-stage alkali washing tower to discharge tar residues periodically; Step 3: The pretreated waste gas enters a catalytic combustion unit, the catalytic combustion unit comprises a box body, a mixed air box is arranged at the air supply opening of the box body, the mixed air box is used for diluting the VOC concentration in the waste gas to below 25% of the lower explosive limit; a plate heat exchanger, a natural gas burner and a catalyst fixed bed are arranged in the box body, the plate heat exchanger is used for preheating the diluted waste gas to 200-250℃, then the waste gas is heated to the catalyst activation temperature of 300-350℃ by the natural gas burner, the catalyst in the catalyst fixed bed decomposes VOC into CO2 and H2O, the reaction heat makes the temperature rise to 400-450℃ to form high-temperature purified gas, and the high-temperature purified gas is discharged from the discharge opening of the box body after recovering waste heat by the plate heat exchanger; Step 4: The purified gas discharged from the discharge opening of the box body is introduced into a chimney by an induced draft fan and discharged from the chimney; In the method, PLC integrated control is used to monitor the waste gas flow, temperature and concentration parameters in real time, and to automatically adjust the spray amount and heating power.

2. The method according to claim 1, wherein An explosion-proof valve is arranged on the pipeline between the air outlet of the fan and the air inlet of the first-stage water spray tower in step 2.

3. The method according to claim 1, wherein the VOCs are treated by, The first-stage water spray tower in step 2 comprises a water washing cylinder, the water washing cylinder is internally provided with a first spray disc, a first filler layer and a first mist eliminator, the water washing cylinder is externally provided with a water washing circulating pump, the inlet of the water washing circulating pump is connected to the lower end of the water washing cylinder through a first pipeline, a first on-off valve is arranged on the first pipeline, the outlet of the water washing circulating pump is connected to the first spray disc through a second pipeline, a first flow valve is arranged on the second pipeline, and the first on-off valve and the first flow valve are linked and controlled.

4. The method according to claim 1, wherein the method is characterized by, The second-stage alkali washing tower in step 2 comprises an alkali washing cylinder, the alkali washing cylinder is internally provided with a second spray disc, a second filler layer and a second mist eliminator, the alkali washing cylinder is externally provided with an alkali solution circulating pump, the inlet of the alkali solution circulating pump is connected to the lower end of the alkali washing cylinder through a third pipeline, a second on-off valve is arranged on the third pipeline, the outlet of the alkali solution circulating pump is connected to the second spray disc through a fourth pipeline, a second flow valve is arranged on the fourth pipeline, and the second flow valve and the second on-off valve are linked and controlled.

5. The method according to claim 1, wherein the method is characterized by, The natural gas burner in step 3 is connected with a natural gas system and an oxygen supplement system respectively, the natural gas system comprises a natural gas pipeline, and a filter, a check valve, a pressure transmitter and a pressure gauge are sequentially arranged on the pipeline; the oxygen supplement system comprises an oxygen pipeline, and an electric pump, an expansion joint and a filter are sequentially arranged on the pipeline.

6. The method for VOC treatment in the process of producing battery anode material in a tunnel kiln according to claim 1, characterized in that, The catalyst in step 3 is a supported noble metal catalyst with Pt / Pd as active components.

7. A system for carrying out the method of any one of claims 1 to 6, characterized in that The system comprises a VOC collecting device, a fan, a two-stage spray tower pretreatment system, a catalytic combustion unit and an induced draft fan which are sequentially connected, a mixing box, a plate heat exchanger, a natural gas burner and a catalyst fixed bed are arranged in the box of the catalytic combustion unit, and the system is integrally controlled by a PLC controller.

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