Tail gas recycling system

Abstract

The invention provides a tail gas recycling system, which comprises: a first reaction tank in which a first material and a second material are arranged, so that gas to be recycled is formed through the reaction of the first material and the second material; a third material is arranged in the second reaction tank, the first reaction tank and the second reaction tank are communicated through a first circulating pipe, and gas to be recycled enters the second reaction tank through the first circulating pipe so as to react with the third material to form a first material; and the first valve is arranged on the first circulating pipe, and the opening degree of the first valve is adjustable. The method solves the problem of environmental pollution caused by the fact that carbon dioxide generated by hydrometallurgy in the prior art cannot be recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of tail gas treatment, and more particularly, to a tail gas recycling system. Background Art

[0002] In hydrometallurgy, impurity metals such as iron and aluminum in acidic solutions usually exist in the form of ions, and carbonates such as magnesium carbonate and calcium carbonate can adjust the pH value of the solution to form insoluble hydroxide precipitates of these impurity metal ions. For example, magnesium carbonate can react with sulfuric acid and impurity aluminum ions in the acidic solution to form magnesium nitrate and aluminum hydroxide and produce carbon dioxide. Finally, the aluminum hydroxide precipitate can be separated from the solution by means of filtration and other methods to achieve the purpose of separating impurities.

[0003] First reaction tank:

[0004] MgCO3 + Al 3+ + H + =Mg 2+ + Al(OH)3 + CO2

[0005] Second reaction tank:

[0006] MgO + CO2 = MgCO3

[0007] Therefore, a large amount of carbon dioxide is generated during the process of hydrometallurgy. The carbon dioxide cannot be recycled and is mostly discharged into the atmosphere through mechanical exhaust, which is likely to cause environmental pollution. Summary of the Invention

[0008] The main object of the present invention is to provide a tail gas recycling system to solve the problem of environmental pollution caused by the inability to recycle carbon dioxide generated in existing hydrometallurgy.

[0009] To achieve the above object, the present invention provides a tail gas recycling system, including: a first reaction tank, in which a first material and a second material are arranged to form a gas to be recycled through the reaction of the first material and the second material; a second reaction tank, in which a third material is arranged, and the first reaction tank and the second reaction tank are connected through a first flow pipe, and the gas to be recycled enters the second reaction tank through the first flow pipe to react with the third material to form the first material; a first valve, which is arranged on the first flow pipe, and the opening degree of the first valve is adjustable.

[0010] Furthermore, the tail gas recycling system further includes a mixing component, and the mixing component includes a flow member, which has a first port, a second port and a third port. The first port, the second port and the third port are all connected to the inner cavity of the flow member. The first port is connected to the first flow pipe, and the third port is connected to the inner cavity of the second reaction tank.

[0011] Further, the mixing assembly includes a second flow pipe and a pump body. The second port is communicated with one end of the second flow pipe, and the inner cavity of the second reaction tank is communicated with the other end of the second flow pipe. The pump body is arranged on the second flow pipe to pump the third material in the second flow pipe into the flow member.

[0012] Further, the mixing assembly further includes a third flow pipe. Two ends of the third flow pipe are respectively communicated with the inner cavity above the second reaction tank and the first flow pipe.

[0013] Further, the flow member is a Venturi tube.

[0014] Further, the tail gas recycling system further includes a third material storage member and a fourth flow pipe. The first end of the fourth flow pipe is communicated with the inner cavity of the third material storage member, and the inner cavity of the second reaction tank is communicated with the second end of the fourth flow pipe.

[0015] Further, the tail gas recycling system further includes a second valve. The second valve is arranged on the fourth flow pipe and is arranged to be openable and closable to control the on-off of the fourth flow pipe.

[0016] Further, the mixing assembly further includes a fifth flow pipe and a first material storage member. Two ends of the fifth flow pipe are respectively communicated with the inner cavity of the first material storage member and the inner cavity of the second reaction tank, so that the first material in the second reaction tank enters the first material storage member. The first material storage member and the first reaction tank are connected through a seventh flow pipe.

[0017] Further, the tail gas recycling system further includes a third valve. The third valve is arranged on the fifth flow pipe and is arranged to be openable and closable to control the on-off of the fifth flow pipe.

[0018] Further, the tail gas recycling system further includes a first detection member. The first detection member is used to detect the real-time pH value of the third material in the second reaction tank. The first detection member is communicatively connected with the first valve to adjust the opening degree of the first valve to 0 when the real-time pH value is equal to the preset pH value.

[0019] Applying the technical solution of the present invention, the tail gas recycling system includes a first reaction tank, a second reaction tank, a first valve, and a first flow pipe. The gas to be recycled generated in the first reaction tank enters the second reaction tank through the first flow pipe. The gas to be recycled reacts with a third material to form a first material, and the first material can be returned to the first reaction tank for use. This not only reduces the direct emission of the gas to be recycled, reduces the pollution to the atmospheric environment, but also saves the production cost of the first material, achieving a win-win situation of economic benefits and environmental benefits, thus solving the problem of environmental pollution caused by the inability to recycle carbon dioxide generated in the existing hydrometallurgy technology. At the same time, by precisely adjusting the opening degree of the first valve, the flow rate of the gas to be recycled entering the second reaction tank can be effectively controlled, and the generation rate of the first material can be optimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 A schematic diagram of the tail gas recycling system according to the present invention is shown.

[0022] Among them, the above-mentioned drawings include the following reference numerals:

[0023] 10. First reaction tank; 20. Second reaction tank; 30. First flow pipe; 40. First valve; 50. Second flow pipe; 51. Pump body; 52. Flow member; 53. First port; 54. Second port; 55. Third port; 56. Third flow pipe; 70. Fourth flow pipe; 90. Fifth flow pipe; 91. Concentrating pipe; 92. Sixth flow pipe; 93. Fifth valve; 17. First material storage member; 18. Seventh flow pipe; 171. Third material storage member. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] In the description of the present application, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Without contrary instructions, these orientation words do not indicate and imply that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present application; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0027] Please refer to Figure 1 , the present invention provides an exhaust gas recycling system, including: a first reaction tank 10, in which a first material and a second material are provided to form a gas to be recycled through the reaction of the first material and the second material; a second reaction tank 20, in which a third material is provided, and the first reaction tank 10 and the second reaction tank 20 are connected through a first flow pipe 30, and the gas to be recycled enters the second reaction tank 20 through the first flow pipe 30 to react with the third material to form the first material; a first valve 40, which is provided on the first flow pipe 30, and the opening degree of the first valve 40 is adjustable.

[0028] The tail gas recycling system of the present invention includes a first reaction tank 10, a second reaction tank 20, a first valve 40 and a first circulation pipe 30. The gas to be recycled generated in the first reaction tank 10 enters the second reaction tank 20 through the first circulation pipe 30. The gas to be recycled reacts with a third material to form a first material, and the first material can be returned to the first reaction tank 10 for use. This not only reduces the direct emission of the gas to be recycled, reduces the pollution to the atmospheric environment, but also saves the production cost of the first material, achieving a win-win situation of economic and environmental benefits, thus solving the problem of environmental pollution caused by the unrecoverable carbon dioxide generated in the existing hydrometallurgy technology. At the same time, by precisely adjusting the opening degree of the first valve 40, the flow rate of the gas to be recycled entering the second reaction tank 20 can be effectively controlled, and the generation rate of the first material can be optimized.

[0029] Specifically, the first material is a carbonate slurry such as magnesium carbonate and calcium carbonate, the second material is an acidic slurry containing impurity aluminum or iron ions, the third material is magnesium oxide or lime milk slurry, and the gas to be recycled is carbon dioxide.

[0030] Specifically, the concentration of the carbonate slurry of the first material is 10% - 20%. The pH of the second material is 1.5 - 4. The temperature in the second reaction tank 20 is 75 - 85 °C. The concentration of the third material is 5% - 10%.

[0031] Specifically, the number of the second reaction tanks 20 is 2 - 4. The tail gas recycling system further includes a central pipe 91, a sixth circulation pipe 92 and a fifth valve 93. The central pipe 91 is connected to the inner cavity of the first reaction tank 10 through the sixth circulation pipe 92. There are multiple first reaction tanks 10, multiple sixth circulation pipes 92, and multiple fifth valves 93. The multiple fifth valves 93 and the multiple sixth circulation pipes 92 are arranged in one-to-one correspondence, and the multiple sixth circulation pipes 92 and the multiple first reaction tanks 10 are arranged in one-to-one correspondence. Each fifth valve 93 is arranged on the corresponding sixth circulation pipe 92, and the opening degree of each fifth valve 93 is adjustable. The central pipe 91 is connected to the second reaction tank 20 through the first circulation pipe 30.

[0032] In specific implementation, due to the different distances between each first reaction tank 10 and each second reaction tank 20, the opening degree of the fifth valve 93 corresponding to the first reaction tank 10 far from each second reaction tank 20 is large, and the opening degree of the fifth valve 93 corresponding to the first reaction tank 10 close to each second reaction tank 20 is small. Since the suction force of each second reaction tank 20 on each first reaction tank 10 is the same, such a setting can avoid the large suction force of each second reaction tank 20 reducing the air pressure in the first reaction tank 10 close to each second reaction tank 20, resulting in the air pressure in the first reaction tank 10 being less than the atmospheric pressure and the phenomenon that the first reaction tank 10 is crushed.

[0033] In this embodiment, the tail gas recycling system further includes a mixing component. The mixing component includes a flow member 52, and the flow member 52 has a first port 53, a second port 54, and a third port 55. The first port 53, the second port 54, and the third port 55 are all in communication with the inner cavity of the flow member 52. The first port 53 is in communication with the first flow pipe 30, and the third port 55 is in communication with the inner cavity of the second reaction tank 20.

[0034] Specifically, by using the flow member 52 with multiple ports, it helps the gas to be recycled and the third material to come into more sufficient contact and mixing under the interaction of high pressure and low pressure. By improving the mixing efficiency of the gas and the material, the ability of the gas to be absorbed and converted can be enhanced, effectively reducing the time cost of processing the gas to be recycled and the impact on the environment.

[0035] In this embodiment, the tail gas recycling system further includes a mixing component. The mixing component includes a second flow pipe 50 and a pump body 51. The second port 54 is in communication with one end of the second flow pipe 50, and the inner cavity of the second reaction tank 20 is in communication with the other end of the second flow pipe 50. The pump body 51 is arranged on the second flow pipe 50 to pump the third material in the second flow pipe 50 into the flow member 52.

[0036] Specifically, by precisely controlling the flow rate of the third material entering the second reaction tank 20 through the pump body 51, the contact area and time between the third material and the gas to be recycled can be significantly increased, making the reaction between the gas to be recycled and the third material more sufficient. Especially when dealing with gases that are difficult to dissolve in water such as sulfur dioxide and nitrogen oxides, the absorption and conversion efficiency can be significantly improved.

[0037] In this embodiment, the flow member 52 is a Venturi tube.

[0038] Specifically, since the flow member 52 is a Venturi tube, which has a small resistance to the fluid, it can effectively reduce the energy consumption of the gas to be recycled and the third material, while improving the mixing effect of the gas to be recycled and the third material.

[0039] During specific implementation, a Venturi tube is a fluid dynamics device, and its design includes a gradually narrowing throat region, followed by a gradually widening diffuser region. When the fluid (in this case, the mixed flow of the third material and the gas to be recycled) passes through the throat region, due to the reduction of the flow channel area, the flow velocity will increase significantly, and the pressure will decrease due to the increase in the flow velocity. This is the application of Bernoulli's principle. In the diffuser region, the flow channel area increases again, the flow velocity slows down, and the pressure recovers. When the pump body 51 efficiently pumps the third material from the second flow pipe 50 into the Venturi tube, the third material enters the throat region of the Venturi tube at a relatively high speed under the action of the pump body 51. There, due to the narrowness of the flow channel, the velocity of the third material will be further increased while the pressure drops, forming a low-pressure area. According to hydrodynamics, the gas to be recycled (usually at a relatively high pressure) will be attracted into this low-pressure area and come into strong contact and mixing with the third material. In the throat area of the venturi tube, the contact area between the gas to be recycled and the third material is greatly increased due to the high-speed movement of the fluid, which promotes the full contact between the gas and the liquid and improves the efficiency of gas dissolution or reaction. ​ ​​ ​ As the fluid enters the diffusion region, the pressure gradually recovers and the flow rate slows down, which provides additional time for the gas and liquid to undergo chemical reactions, thereby improving the completeness of the reaction and the quality of the products. Therefore, by efficiently pumping the third material into the Venturi tube and utilizing its structural characteristics, an environment with alternating high and low pressures can be created, promoting the full contact and mixing of the gas to be recovered and the third material, thereby improving the reaction efficiency and achieving the effective recovery and utilization of the gas. In addition, this design can also effectively control the hydrodynamic parameters of the system, such as the flow rate and pressure, ensuring the stable operation of the system, which plays an important role in enhancing the overall performance and environmental protection benefits of the tail gas recycling system.

[0040] In this embodiment, the mixing assembly further includes a third flow pipe 56, and both ends of the third flow pipe 56 are respectively communicated with the inner cavity above the second reaction tank 20 and the first flow pipe 30.

[0041] Specifically, by respectively communicating both ends of the third flow pipe 56 with the inner cavity above the second reaction tank 20 and the first flow pipe 30, the unreacted gas to be recovered above the second reaction tank 20 re-enters the first flow pipe 30 through the third flow pipe 56, which helps to make full use of the gas to be recovered and promotes the full contact reaction between the gas to be recovered and the third material, significantly improving the reaction rate and efficiency between the gas to be recovered and the third material.

[0042] In this embodiment, the tail gas recycling system further includes a third material storage member 171 and a fourth flow pipe 70. The first end of the fourth flow pipe 70 is communicated with the inner cavity of the third material storage member 171, and the inner cavity of the second reaction tank 20 is communicated with the second end of the fourth flow pipe 70.

[0043] Specifically, the third material storage member 171, as an important part of the entire tail gas recycling system, ensures the continuous and stable supply of the third material, providing a reliable material guarantee for the waste gas treatment in the large-scale continuous production process. By connecting the third material storage member 171 and the inner cavity of the second reaction tank 20 through the fourth flow pipe 70, it ensures that the third material in the third material storage member 171 smoothly enters the second reaction tank 20.

[0044] In this embodiment, the tail gas recycling system further includes a second valve. The second valve is arranged on the fourth flow pipe 70 and is arranged to be openable and closable to control the on-off of the fourth flow pipe 70.

[0045] Specifically, by setting the second valve, the tail gas recycling system can dynamically adjust the supply amount of the third material according to the internal state of the second reaction tank 20, achieving precise control of the reaction conditions between the gas to be recovered and the third material, which is particularly suitable for the waste gas recycling in fine chemical production.

[0046] In this embodiment, the mixing component further includes a fifth circulation pipe 90 and a first material storage member 17. The two ends of the fifth circulation pipe 90 are respectively connected to the inner cavity of the first material storage member 17 and the second reaction tank 20, so that the first material in the second reaction tank 20 enters the first material storage member 17, and the first material storage member 17 and the first reaction tank 10 are connected through a seventh circulation pipe 18.

[0047] Specifically, the fifth circulation pipe 90 is used to connect the second reaction tank 20 and the first material storage member 17, and the first material in the first material storage member 17 returns to the first reaction tank 10 through the seventh circulation pipe 18, so that the tail gas recycling system can form a complete closed-loop material cycle, which not only improves the self-sufficiency ability of the tail gas recycling system, but also reduces the usage cost of the first material.

[0048] Specifically, a water pump is provided on the seventh circulation pipe 18 for pumping out the first material in the first material storage member 17.

[0049] In this embodiment, the tail gas recycling system further includes a third valve. The third valve is provided on the fifth circulation pipe 90 and is provided in an openable and closable manner to control the on-off of the fifth circulation pipe 90.

[0050] Specifically, the setting of the third valve enables the tail gas recycling system to flexibly adjust the supply rate of the first material according to the fluctuations in production demand, effectively cope with the adjustment of the treatment speed of the gas to be recycled during the production peak and trough periods, and improve the economy and adaptability of the tail gas recycling system.

[0051] In this embodiment, the tail gas recycling system further includes a first detection member. The first detection member is used to detect the real-time pH value of the third material in the second reaction tank 20. The first detection member is communicatively connected to the first valve 40 so that when the real-time pH value is equal to the preset pH value, the opening degree of the first valve 40 is adjusted to 0.

[0052] Specifically, by using the first detection member to detect the real-time pH value of the third material in the second reaction tank 20, when the real-time pH value is equal to the preset pH value, it indicates that the reaction between the third material in the second reaction tank 20 and the gas to be recycled has ended. By controlling the opening degree of the first valve 40 to be adjusted to 0, it is possible to timely avoid the continuous introduction of the gas to be recycled into the second reaction tank 20. After waiting for the new third material to be introduced into the second reaction tank 20, the opening degree of the first valve 40 is adjusted to be greater than 0, and the gas to be recycled is re-introduced.

[0053] Specifically, the reaction time between the gas to be recycled and the third material in the second reaction tank 20 is 2 to 4 hours, and the pH in the second reaction tank 20 at the end of the reaction is 7 to 9. That is, the preset pH is 7 to 9.

[0054] In specific implementation, the pH of the first material is 7 to 9, the first material is calcium carbonate slurry, the concentration of the first material is 20%, the third material is lime milk, the temperature in the second reaction tank 20 is 80 °C, the concentration of the third material is 10%, the reaction time is 2 hours, the pH at the end of the reaction is 8, the absorption rate of the gas to be recycled is 50%, and the concentration of the first material generated in the second reaction tank 20 is 20%.

[0055] In specific implementation, the pH of the first material is 7 to 9, the first material is calcium carbonate slurry, the concentration of the first material is 10%, the third material is lime milk, the temperature in the second reaction tank 20 is 80 °C, the concentration of the third material is 5%, the reaction time is 3 hours, the pH at the end of the reaction is 8, the absorption rate of the gas to be recycled is 50%, and the concentration of the first material generated in the second reaction tank 20 is 10%.

[0056] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0057] The tail gas recycling system of the present invention includes a first reaction tank 10, a second reaction tank 20, a first valve 40, and a first flow pipe 30. The gas to be recycled generated in the first reaction tank 10 enters the second reaction tank 20 through the first flow pipe 30. The gas to be recycled reacts with the third material to form the first material, and the first material can be returned to the first reaction tank 10 for use. This not only reduces the direct emission of the gas to be recycled and reduces the pollution to the atmospheric environment, but also saves the production cost of the first material, achieving a win-win situation of economic and environmental benefits, thereby solving the problem of environmental pollution caused by the inability to recycle carbon dioxide generated in wet metallurgy in the prior art. At the same time, by precisely adjusting the opening of the first valve 40, the flow rate of the gas to be recycled entering the second reaction tank 20 can be effectively controlled, and the generation rate of the first material can be optimized.

[0058] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the corresponding explanations are made for the spatial relative descriptions used herein.

[0059] In addition, it should be noted that the use of terms such as "first" and "second" to define components is only for the convenience of differentiating the corresponding components. Without further statement, the above terms have no special meaning, and thus should not be construed as limiting the protection scope of the present application.

[0060] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tail gas recycling system, characterized in that: include: A first reaction tank (10), wherein a first material and a second material are arranged in the first reaction tank (10), so that the first material and the second material react to form a gas to be recovered; a second reaction tank (20), wherein a third material is arranged in the second reaction tank (20), the first reaction tank (10) and the second reaction tank (20) are connected via a first circulation pipe (30), and the gas to be recovered enters the second reaction tank (20) via the first circulation pipe (30) to react with the third material to form the first material; A first valve (40), wherein the first valve (40) is arranged on the first flow pipe (30), and the opening degree of the first valve (40) is adjustable.

2. The tail gas recycling system according to claim 1, characterized in that: The exhaust gas recycling system also includes a mixing component, which includes a flow-transfer element (52), wherein the flow-transfer element (52) has a first port (53), a second port (54) and a third port (55), wherein the first port (53), the second port (54) and the third port (55) are all connected to the inner cavity of the flow-transfer element (52), the first port (53) is connected to the first circulation pipe (30), and the third port (55) is connected to the inner cavity of the second reaction tank (20).

3. The tail gas recycling system according to claim 2, characterized in that: The mixing assembly includes a second circulation tube (50) and a pump body (51), the second port (54) is connected to one end of the second circulation tube (50), the inner cavity of the second reaction tank (20) is connected to the other end of the second circulation tube (50), and the pump body (51) is arranged on the second circulation tube (50) to pump the third material in the second circulation tube (50) into the flow member (52).

4. The tail gas recycling system according to claim 2, characterized in that: The mixing assembly further comprises a third flow tube (56), both ends of which are respectively connected to the inner cavity above the second reaction tank (20) and the first flow tube (30).

5. The tail gas recycling system according to claim 3, characterized in that: The flow transfer element (52) is a Venturi tube.

6. The tail gas recycling system according to claim 2, characterized in that: The exhaust gas recycling system also includes a third material storage component (171) and a fourth flow pipe (70), wherein the first end of the fourth flow pipe (70) is connected to the inner cavity of the third material storage component (171), and the inner cavity of the second reaction tank (20) is connected to the second end of the fourth flow pipe (70).

7. The tail gas recycling system according to claim 6, characterized in that: The exhaust gas recycling system further comprises a second valve, which is arranged on the fourth flow pipe (70), and the second valve can be opened and closed to control the opening and closing of the fourth flow pipe (70).

8. The tail gas recycling system according to claim 7, characterized in that: The mixing assembly further comprises a fifth circulation tube (90) and a first material storage element (17), wherein two ends of the fifth circulation tube (90) are respectively connected to the inner cavity of the first material storage element (17) and the inner cavity of the second reaction tank (20), so that the first material in the second reaction tank (20) enters the first material storage element (17), and the first material storage element (17) and the first reaction tank (10) are connected via a seventh circulation tube (18).

9. The tail gas recycling system according to claim 8, characterized in that: The exhaust gas recycling system further comprises a third valve, which is arranged on the fifth flow pipe (90). The third valve can be opened and closed to control the opening and closing of the fifth flow pipe (90).

10. The tail gas recycling system according to claim 1, characterized in that: The exhaust gas recycling system also includes a first detection component, which is used to detect the real-time pH value of the third material in the second reaction tank (20). The first detection component is communicatively connected with the first valve (40) so that when the real-time pH value is equal to the preset pH value, the opening of the first valve (40) is adjusted to 0.

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