A device and method for recovering and treating water-soluble waste gas

Abstract

The present application relates to a water-soluble waste gas recovery and treatment device and method, the recovery and treatment device comprises a packing tower, which comprises, from bottom to top, an air intake space, an unmodified metal mesh packing layer, a gas-liquid distributor, a modified metal mesh packing layer, a liquid distributor and a first exhaust port; the hydrophilicity of the modified metal mesh packing layer is greater than that of the unmodified metal mesh packing layer; a solution circulation pump, one end of which is connected to the air intake space and the other end is connected to the gas-liquid distributor; a pure water input pipeline, which is connected to the liquid distributor; a first valve is provided on the pure water input pipeline; a pure water circulation pump, one end of which is connected to the gas-liquid distributor and the other end is connected to the liquid distributor; a second valve is provided between the pure water circulation pump and the gas-liquid distributor; and a third valve is provided on the upper material discharge pipeline. The present invention can reduce the concentration of organic solvents in the final exhaust gas, increase the concentration of the recovered solution, has high environmental protection and good energy-saving effect, and reduces the subsequent processing cost.

Description

Technical Field

[0001] The present application relates to the technical field of waste gas recovery and treatment, and in particular to a device and method for recovering and treating water-soluble waste gas. Background Art

[0002] In the process of industrial production, some chemical solvents are usually used. In the process of production, it is inevitable to produce waste gas containing these chemical solvents. On the one hand, these chemical solvents are not easy to degrade, which affects the environment and may have certain toxicity. The concentration of chemical solvents in the waste gas needs to be controlled below a certain standard before it can be discharged. On the other hand, these chemical solvents have good economic value and need to be recycled and reused. Some chemical solvents have the property of being able to dissolve in pure water in any proportion, such as N-methylpyrrolidone, N,N-dimethylacetamide, etc. In the process of industrial production, these organic solvents are easily soluble in water, and water absorption is used to treat these waste gases. However, the existing treatment method has the defect that the organic solvent content of the final exhaust gas is too high, and the solubility of the recovered solution is not high enough.

[0003] Take N-methylpyrrolidone as an example. N-methylpyrrolidone, referred to as NMP, is an important chemical solvent and is often used as a solvent in the production of metal ion batteries. In the industrial production process, NMP waste gas is usually treated and recycled to reduce the NMP content in the waste gas before discharge, and NMP is recovered. The traditional method uses a packed tower to circulate NMP solution to absorb the exhaust gas. However, due to the physical properties of the NMP solution, even if thermodynamic equilibrium is fully reached, the exhaust gas after the NMP solution is absorbed will always contain NMP components. Although it can meet general emission standards, for some high-standard areas, the concentration of NMP in the exhaust gas is still relatively high. The group standard "Technical Guidelines for the Calculation and Control of NMP Waste Gas Emissions in the Lithium-ion Battery Industry" pointed out that the domestic NMP emission concentration level is 5~10mg / m 3 .

[0004] Since NMP can be mixed with water in any proportion, the use of pure water can reduce the NMP concentration in the exhaust gas to a lower level, and the NMP content can be as low as 1 mg / m 3 However, according to the requirements of the traditional packing layer, the spray density of the liquid phase needs to reach 0.2m 3 / (m 2 .h) or more to ensure the wetting of the packing layer, thereby ensuring the absorption effect of NMP, but this results in the concentration of the final NMP recovery solution being too low, only reaching about 40% to 50%. Subsequent purification treatment of the low-concentration NMP recovery solution is required, which increases energy consumption and cost.

[0005] In summary, in the recovery and treatment process of waste gas containing N-methylpyrrolidone, N,N-dimethylacetamide, etc., it is necessary to reduce the concentration of organic solvents in the final exhaust gas and increase the concentration of the recovered liquid. Summary of the invention

[0006] Based on this, it is necessary to provide a device and method for recovering and treating water-soluble waste gas, and its specific technical solution is as follows.

[0007] A device for recovering and treating water-soluble waste gas, comprising:

[0008] The packing tower comprises, from bottom to top, an air inlet space, an unmodified metal mesh packing layer, a gas-liquid distributor, a modified metal mesh packing layer, a liquid distributor and a first exhaust port; the gas-liquid distributor comprises a liquid storage space, and a gas flow channel and a liquid flow channel arranged in the liquid storage space; the hydrophilicity of the modified metal mesh packing layer is greater than that of the unmodified metal mesh packing layer;

[0009] A solution circulation pump, one end of which is connected to the air intake space and the other end of which is connected to the gas-liquid distributor, is used to transport the solution in the air intake space to the liquid storage space;

[0010] A pure water input pipeline is connected to the liquid distributor and is used to inject pure water into the packed tower; a first valve is provided on the pure water input pipeline;

[0011] A pure water circulation pump, one end of which is connected to the gas-liquid distributor, and the other end of which is connected to the liquid distributor; a second valve is provided between the pure water circulation pump and the gas-liquid distributor;

[0012] The upper material discharge pipeline is connected to the air intake space at one end and to the gas-liquid distributor at the other end, and is used to discharge the liquid in the liquid storage space to the air intake space; a third valve is provided on the upper material discharge pipeline.

[0013] Furthermore, the static water contact angle of the surface of the unmodified metal wire mesh filler layer is between 70° and 80°; the static water contact angle of the modified metal wire mesh filler layer is between 0° and 15°.

[0014] Furthermore, a heat exchanger is provided between the solution circulation pump and the gas-liquid distributor.

[0015] Furthermore, the liquid storage space includes an outer wall and a bottom wall;

[0016] The gas flow channel comprises a first tube body; the first tube body is connected to the bottom wall, one end of the first tube body extends downward through the bottom wall and a second air inlet is provided at the bottom, and the other end of the first tube body extends upward through the bottom wall and a top is blocked; a second exhaust port is provided on the side of the first tube body, and the second exhaust port is higher than the bottom wall;

[0017] The liquid flow channel includes a second tube body; the second tube body is connected to the bottom wall, one end of the second tube body extends downward through the bottom wall and a second liquid discharge port is provided at the bottom, and the other end extends upward through the bottom wall and is sealed at the top; a liquid inlet is provided on the side of the second tube body, and the liquid inlet is higher than the bottom wall.

[0018] Furthermore, an overflow port is provided below the second exhaust port.

[0019] Furthermore, the second tube body includes a main body and an enlarged head; the enlarged head is connected to the end of the main body; the liquid inlet is arranged on the side of the enlarged head; the minimum radial cross-section of the tube body is S1, the total opening area of ​​the liquid inlet is S2, and the maximum radial cross-section of the enlarged head is S3; S1:S2=1:1~2; S1:S3=1:1.3~3.

[0020] Furthermore, the second liquid discharge port is an oblique port, and the angle between the oblique port and the horizontal plane is 45° to 60°.

[0021] A method for using any of the above-mentioned recycling and processing devices comprises the following steps:

[0022] Waste gas recovery and treatment stage:

[0023] Open the first valve, and close the second and third valves;

[0024] The exhaust gas is continuously introduced into the air intake space from the bottom of the tower, and the exhaust gas flows in the direction of the first exhaust port;

[0025] Pure water is continuously injected into the liquid distributor through the pure water input pipeline, so that the pure water flows through the modified metal wire mesh filler layer to form a low-concentration recovery solution and enters the gas-liquid distributor;

[0026] A solution circulation pump is used to continuously transport the high-concentration recovery solution in the air intake space to the gas-liquid distributor to mix with the low-concentration recovery solution;

[0027] The mixed solution in the gas-liquid distributor is made to flow through the unmodified metal wire mesh filler layer to form a high-concentration recovery solution;

[0028] Shutdown and Wetting Stage:

[0029] Step 1: Stop the exhaust gas from entering the air intake space;

[0030] Step 2: close the solution circulation pump and the first valve, and transfer the high-concentration recovery solution in the air intake space to the outside;

[0031] Step 3: Open the third valve to transport the mixed solution in the gas-liquid distributor into the air inlet space;

[0032] Step 4: Open the first valve, wait for the pure water to clean the modified metal mesh packing layer, and then close the third valve;

[0033] Step 5: When the water level in the gas-liquid distributor reaches a preset height, close the first valve, and open the second valve and the pure water circulation pump to keep the modified metal wire mesh filler layer moist.

[0034] Furthermore, the spray density of pure water entering the modified metal wire mesh packing layer is 0.02~0.2m 3 / (m 2 h), the spray density of the mixed solution in the gas-liquid distributor entering the unmodified metal wire mesh packing layer is 0.2~200m 3 / (m 2 h).

[0035] Furthermore, in the waste gas recovery stage, the waste gas is treated by passing through the unmodified metal wire mesh filler layer so that the temperature is 20°C to 35°C and the relative humidity is 90% to 100%.

[0036] Beneficial effects: The water-soluble waste gas recovery and treatment device and method provided by the present invention adopts a solution circulation pump to circulate a high-concentration solution to ensure the wetting of the unmodified metal wire mesh filler layer. A modified metal wire mesh filler layer is arranged above the unmodified metal wire mesh filler layer, and pure water is used to wet the modified metal wire mesh filler layer to improve the absorption effect of organic solvents in the waste gas and reduce the concentration of organic solvents in the final exhaust gas to 1mg / m 3 The following; improve the hydrophilicity of the modified metal mesh packing layer, thereby reducing the modified metal mesh packing layer's demand for spray density, the external water added during the treatment process only needs to meet the modified metal mesh packing layer's wetting requirement, the overall amount of external water added is small, so that the final recovered solution concentration is high, can reach more than 90%, highly environmentally friendly and energy-saving effect, reducing subsequent processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is the overall schematic diagram of the recycling and processing device;

[0039] Figure 2 is a schematic diagram of a packed tower;

[0040] Figure 3 is a schematic diagram of a gas-liquid distributor;

[0041] Figure 4is a top view of the gas-liquid distributor;

[0042] Figure 5 This is one of the state diagrams of the gas-liquid distributor;

[0043] Figure 6 is a schematic diagram of the liquid flow channel;

[0044] Figure 7 This is the second state diagram of the gas-liquid distributor.

[0045] Description of reference numerals: 1. solution circulation pump; 2. pure water input pipeline; 3. pure water circulation pump; 4. upper material discharge pipeline; 5. air intake space; 6. unmodified metal wire mesh packing layer; 7. gas-liquid distributor; 8. modified metal wire mesh packing layer; 9. liquid distributor; 10. first exhaust port; 101. defoamer;

[0046] 11. Heat exchanger;

[0047] 21. First valve;

[0048] 31. Second valve;

[0049] 41. The third valve;

[0050] 51. a first air inlet; 52. a first liquid discharge outlet;

[0051] 71, liquid storage space; 72, first tube body; 73, second air inlet; 74, second air outlet; 75, second tube body; 76, second liquid discharge outlet; 77, liquid inlet; 78, overflow outlet; 79, enlarged head; 70, body;

[0052] 711. Outer wall; 712. Bottom wall. DETAILED DESCRIPTION

[0053] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0054] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0055] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0056] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0057] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0058] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0059] Example 1

[0060] This embodiment provides a water-soluble waste gas recovery and treatment device, referring to Figure 1 As shown, it includes a packed tower, a solution circulation pump 1, a pure water input pipeline 2, a pure water circulation pump 3 and an upper material discharge pipeline 4. It should be noted that the recovery and treatment device provided in this embodiment can be applied to the tail gas treatment and recovery of water-soluble solvents, such as N-methylpyrrolidone, N,N-dimethylacetamide, etc. In the following embodiments, N-methylpyrrolidone is used as an example for illustration and is uniformly referred to as NMP.

[0061] Specifically, refer to Figure 2 As shown, the packing tower includes an air inlet space 5, an unmodified metal mesh packing layer 6, a gas-liquid distributor 7, a modified metal mesh packing layer 8, a liquid distributor 9 and a first exhaust port 10 from bottom to top. The first exhaust port 10 is located at the top, so that the waste gas containing NMP flows upward from the bottom of the packing tower and is discharged from the first exhaust port 10 after being treated. The gas-liquid distributor 7 includes a liquid storage space 71, and a gas flow channel and a liquid flow channel arranged in the liquid storage space 71. The liquid storage space 71 can store a certain amount of liquid, and the liquid in the liquid storage space 71 can flow to the unmodified metal mesh packing layer 6 through the liquid flow channel, and the waste gas passing through the unmodified metal mesh packing layer 6 flows upward through the gas flow channel. The hydrophilicity of the modified metal mesh packing layer 8 is greater than that of the unmodified metal mesh packing layer 6, and the spray density required for wetting the modified metal mesh packing layer 8 is smaller than that of the unmodified metal mesh packing layer 6, that is, during the operation, the amount of water required for the modified metal mesh packing layer 8 is smaller. By reducing the spray density required for the modified metal mesh packing layer 8, the overall amount of added water during the treatment process is reduced, so that the concentration of the finally recovered NMP solution is increased.

[0062] Specifically, continue to refer to Figure 1As shown, one end of the solution circulation pump 1 is connected to the air inlet space 5, and the other end is connected to the gas-liquid distributor 7, which is used to transport the high-concentration NMP solution in the air inlet space 5 to the liquid storage space 71. The air inlet space 5 is located below the unmodified metal mesh packing layer 6. After the high-concentration NMP waste gas enters the unmodified metal mesh packing layer 6, it transfers mass with the liquid to obtain a high-concentration NMP solution. The high-concentration NMP solution falls into the air inlet space 5, and is pumped to the gas-liquid distributor 7 by the solution circulation pump 1, and mixed with the low-concentration NMP solution falling from the modified metal mesh packing layer 8. The mixed solution in the gas-liquid distributor 7 then enters the unmodified metal mesh packing layer 6 through the liquid flow channel to transfer mass with the NMP waste gas. By transporting the NMP solution in the air inlet space 5 to the gas-liquid distributor 7, the spray density of the unmodified metal mesh packing layer 6 is actually increased, thereby meeting the wetting requirements of the unmodified metal mesh packing layer 6.

[0063] Specifically, the pure water input pipe 2 is connected to the gas-liquid distributor 7 and is used to inject pure water into the packed tower. During the treatment process, the pure water input pipe 2 is the only external water source for the packed tower, and only needs to meet the spray density of the modified metal wire mesh packing layer 8. Therefore, the amount of external water can be reduced to ensure the concentration of the recovered NMP solution. The concentration of the recovered NMP solution can reach more than 90%. By utilizing the property that pure water can dissolve NMP in any proportion, the waste gas is discharged after mass transfer with pure water, which can greatly reduce the NMP concentration in the final exhaust gas. The NMP component can be reduced to 1 mg / m 3 The following meet the requirements of high emission standards in Europe and other regions.

[0064] It should be noted that, due to the high hydrophilicity of the modified metal mesh packing layer 8, a dry environment will destroy the hydrophilicity of the modified metal mesh packing layer 8, making its wettability worse, thereby having a negative impact on the absorption effect of NMP. NMP waste gas usually has the characteristics of high temperature and low humidity. For example, after the positive electrode of the lithium battery is coated, it needs to be dried. The NMP evaporates through the coated electrode by hot air baking, generating waste gas containing NMP, which has a higher temperature and lower humidity. In order to avoid excessively dry waste gas directly contacting the modified metal mesh packing layer 8 and affecting the hydrophilicity of the modified metal mesh packing layer 8, the waste gas is first passed through the unmodified metal mesh packing layer 6 to be completely wetted, and then enters the modified metal mesh packing layer 8.

[0065] Specifically, one end of the pure water circulation pump 3 is connected to the gas-liquid distributor 7, and the other end is connected to the liquid distributor 9. The upper material discharge pipeline 4 is connected to the air intake space 5 at one end, and is connected to the gas-liquid distributor 7 at the other end, for discharging the liquid in the liquid storage space 71 to the air intake space 5. A first valve 21 is provided on the pure water input pipeline 2; a second valve 31 is provided between the pure water circulation pump 3 and the gas-liquid distributor 7; and a third valve 41 is provided on the upper material discharge pipeline 4. By switching different valves on and off, different working modes of the recycling and processing device can be switched: waste gas recycling and processing mode and shutdown wetting mode. The waste gas recycling and processing mode can recycle and process NMP in the waste gas, and the shutdown wetting mode can ensure that the modified metal wire mesh filler layer 8 is in a wet state to avoid affecting the hydrophilicity of the modified metal wire mesh filler layer 8.

[0066] It should be noted that the pure water referred to in this embodiment does not refer to water completely free of impurities, but rather water that does not contain the organic solvent NMP component, that is, pure water can dissolve NMP in any proportion.

[0067] This embodiment provides a water-soluble waste gas recovery and treatment device, which uses a solution circulation pump 1 to circulate a high-concentration solution to ensure the wetting of the unmodified metal mesh filler layer 6. A modified metal mesh filler layer 8 is arranged above the unmodified metal mesh filler layer 6, and pure water is used to wet the modified metal mesh filler layer 8 to improve the absorption effect of NMP in the waste gas and reduce the NMP concentration in the final exhaust gas to 1 mg / m 3 The following; improve the hydrophilicity of the modified metal mesh packing layer 8, thereby reducing the modified metal mesh packing layer 8's demand for spray density, the external water added during the treatment process only needs to meet the wetting requirement of the modified metal mesh packing layer 8, the overall amount of external water added is small, so that the concentration of the final recovered NMP solution is high, which can reach more than 90%, has high environmental protection and good energy-saving effect, and reduces the subsequent treatment cost.

[0068] Specifically, the hydrophilicity of the modified metal mesh packing layer 8 and the unmodified metal mesh packing layer 6 can be described by the static water contact angle. The smaller the static water contact angle, the higher the hydrophilicity. In the present embodiment, the static water contact angle on the surface of the unmodified metal mesh packing layer 6 is between 70° and 80°; the static water contact angle of the modified metal mesh packing layer is 0°. In the actual production process, in a moist environment, after the modified metal mesh packing layer 8 is in contact with the NMP-containing waste gas for a period of time, that is, after a period of production and treatment, the final static water contact angle of the modified metal mesh packing layer 8 is stabilized at 15°, which is much smaller than the static water contact angle of the unmodified metal mesh packing layer 6, and much lower than the requirement of the unmodified metal mesh packing layer 6 for the spray density.

[0069] Specifically, there are many methods for modifying the hydrophilicity of the modified metal wire mesh filler layer 8, such as chemical etching and chemical oxidation, laser processing, electrochemical method, sol-gel method, etc. However, most of the methods have the disadvantages of high cost, difficult control, and complex process. Chemical etching and chemical oxidation have the advantages of low cost and strong controllability. The specific steps are as follows:

[0070] The first step is to wash away the grease of the wire mesh filler in the filler layer with ethyl acetate or other organic solvents;

[0071] Step 2: Wash the wire mesh filler with clean water;

[0072] Step 3: prepare a 2 mol / L FeCl3 solution, and mix it with HCl and H2O2 in a volume ratio of 15:1:1 to obtain an etching solution, and etch the metal mesh filler;

[0073] Step 4: After chemical etching is completed, wash the metal mesh filler with clean water;

[0074] Step 5: The oxidation liquid uses a mixed solution of CrO3 and H2SO4 to oxidize the metal wire mesh filler, the mass concentration of CrO3 is 250g / L, the mass concentration of H2SO4 is 500g / L, the oxidation temperature is 70~75℃, and the oxidation time is 8min;

[0075] Step 6: After the oxidation of the filler is complete, wash the wire mesh filler.

[0076] The metal mesh filler is modified to be hydrophilic by chemical etching-oxidation method so that the static water contact angle of its surface reaches 0°.

[0077] Specifically, refer to Figure 1 As shown, the air inlet space 5 is provided with a first air inlet 51 and a first liquid discharge port 52, and the first liquid discharge port 52 is located below the first air inlet port 51. Waste gas containing NMP is input into the air inlet space 5 through the first air inlet port 51, and the waste gas flows toward the first exhaust port 10 at the top of the packed tower. The high-concentration NMP solution in the air inlet space 5 is recovered through the first liquid discharge port 52.

[0078] Specifically, refer to Figure 2 As shown, a demister 101 is further provided between the first exhaust port 10 and the modified metal wire mesh packing layer 8. After the exhaust gas is processed by the modified metal wire mesh packing layer 8, a small amount of entrained liquid components are removed by the demister 101 and then discharged to the outside through the first exhaust port 10.

[0079] Specifically, a heat exchanger 11 is provided between the NMP solution circulation pump 1 and the gas-liquid distributor 7. The temperature of the NMP solution transported from the air intake space 5 to the gas-liquid distributor 7 can be adjusted by the heat exchanger 11. When the exhaust gas temperature input into the air intake space 5 is too low, the temperature of the high-concentration NMP solution obtained in the air intake space 5 will drop after passing through the unmodified metal wire mesh filler layer 6, and the temperature of the NMP solution transported into the gas-liquid distributor 7 can be increased by the heat exchanger 11 to control the temperature balance. Conversely, when the exhaust gas temperature input into the air intake space 5 is too high, the temperature of the NMP solution can also be reduced by the heat exchanger 11.

[0080] Specifically, refer to Figure 3 As shown, the liquid storage space 71 includes an outer wall 711 and a bottom wall 712; the liquid storage space 71 is surrounded by the outer wall 711 and the bottom wall 712, and can store the low-concentration NMP solution flowing down after the mass transfer between the pure water in the modified filler and the low-concentration NMP waste gas, and provide a mixing space for the low-concentration NMP solution and the high-concentration NMP solution transported from the air inlet space 5.

[0081] Reference Figure 4 and Figure 5 As shown, the gas flow channel includes a first tube body 72; the first tube body 72 is connected to the bottom wall 712, one end of the first tube body 72 extends downward through the bottom wall 712 and a second air inlet 73 is provided at the bottom, and the other end extends upward through the bottom wall 712 and is sealed at the top; a second exhaust port 74 is provided on the side of the first tube body 72, and the second exhaust port 74 is higher than the bottom wall 712; the liquid flow channel includes a second tube body 75; the second tube body 75 is connected to the bottom wall 712, one end of the second tube body 75 extends downward through the bottom wall 712 and a second liquid discharge port 76 is provided at the bottom, and the other end of the second tube body 75 extends upward through the bottom wall 712 and is sealed at the top; a liquid inlet 77 is provided on the side of the second tube body 75, and the liquid inlet 77 is higher than the bottom wall 712. By setting a blockage at the top of the first tube body 72 and the second tube body 75, it is possible to prevent the liquid flowing down from the modified metal wire mesh filler layer 8 from directly entering the gas flow channel or the liquid flow channel, and the liquid inlet 77 is set to be higher than the bottom wall 712, so that the liquid level of the mixed solution in the liquid storage space 71 is submerged in the liquid inlet 77 before entering the liquid flow channel and flowing downward.

[0082] It should be noted that the height of the second exhaust port 74 is higher than the liquid inlet 77, so as to prevent the liquid from entering the gas flow channel from the second exhaust port 74. In addition, an overflow port 78 is also provided on the first tube body 72, and the height of the overflow port 78 is lower than the second exhaust port 74 and higher than the liquid inlet 77. When the liquid inlet 77 is blocked, the liquid can be discharged downward through the overflow port 78.

[0083] It should be noted that in this embodiment, a plurality of gas flow channels and a plurality of liquid flow channels are provided. Figure 4As shown, a plurality of gas flow channels are evenly arranged in two circles around the center of the gas-liquid distributor 7, and a plurality of liquid flow channels are respectively arranged around each gas flow channel to ensure the uniformity of gas flow and liquid flow.

[0084] Specifically, refer to Figure 6 As shown, the second tube body 75 includes a body 70 and an enlarged head 79; the enlarged head 79 is connected to the end of the body 70, and a transition slope is formed between the enlarged head 79 and the body 70, and the angle of the transition slope relative to the horizontal plane is 60°~75°; the liquid inlet 77 is arranged on the side of the enlarged head 79; the minimum radial section of the tube body is S1, the total opening area of ​​the liquid inlet 77 is S2, and the maximum radial section of the enlarged head 79 is S3; S1:S2=1:1~2; S1:S3=1:1.3~3. Solve the defects of unstable liquid flow and large resistance caused by the side opening.

[0085] In order to better allow the liquid to flow downward to the unmodified metal wire mesh filler layer 6, the second liquid discharge port 76 is an oblique port, and the angle between the oblique port and the horizontal plane is 45° to 60°.

[0086] Example 2

[0087] This embodiment provides a method for using the recovery and treatment device described in Embodiment 1, comprising the following steps. It should be noted that in this embodiment, waste gas containing NMP is also used as an example.

[0088] It is divided into two stages: the waste gas recovery and treatment stage and the shutdown and wetting stage.

[0089] Specifically, the waste gas recovery and treatment stage includes:

[0090] Open the first valve 21, and close the second valve 31 and the third valve 41;

[0091] The NMP waste gas is continuously introduced into the air inlet space 5 from the bottom of the tower, and the NMP waste gas flows in the direction of the first exhaust port 10;

[0092] Continuously inject pure water into the liquid distributor 9 through the pure water input pipeline 2, so that the pure water flows through the modified metal wire mesh filler layer 8 to form a low-concentration NMP solution and enters the gas-liquid distributor 7;

[0093] The high-concentration NMP solution in the air intake space 5 is continuously transported to the gas-liquid distributor 7 by the NMP solution circulation pump 1 to be mixed with the low-concentration NMP solution;

[0094] The mixed solution in the gas-liquid distributor 7 is made to flow through the unmodified metal wire mesh filler layer 6 to form a high-concentration NMP solution.

[0095] It should be noted that in the waste gas recovery treatment stage, the processes of passing NMP waste gas into the air intake space 5, injecting pure water into the liquid distributor 9, and transporting the high-concentration NMP solution in the air intake space 5 to the gas-liquid distributor 7 are all continuously carried out, thereby forming a cyclic treatment process.

[0096] The high-concentration NMP mixed liquid that has passed through the unmodified wire mesh filler layer 6 and flowed into the air inlet space 5 has reached the concentration requirement for recovery, that is, the concentration of the high-concentration NMP solution in the air inlet space 5 has reached more than 90%. During the treatment process, the high-concentration NMP solution at the bottom of the air inlet space 5 is continuously recovered through the first liquid discharge port 52.

[0097] Specifically, in this embodiment, the spray density of pure water entering the modified metal wire mesh filler layer 8 is 0.02~0.2m 3 / (m 2 h), the spray density of the mixed solution in the gas-liquid distributor 7 entering the unmodified metal wire mesh filler layer 6 is 0.2~200m 3 / (m 2 h), and the flow rate of the exhaust gas in the packed tower is controlled to be 1-3 m / s. The temperature of the solution circulating in the liquid storage space 71 is adjusted by the heat exchanger 11, so that the exhaust gas temperature after the unmodified metal wire mesh packing layer 6 is controlled at 20°C-35°C and the relative humidity is 90%-100%. The NMP concentration of the exhaust gas discharged after the recovery treatment is 1 mg / m 3 Below, the solubility of the recovered NMP solution is 90% or more.

[0098] Specifically, the shutdown and wetting phase includes:

[0099] The first step: stop the NMP waste gas from entering the air intake space 5;

[0100] Step 2: Close the NMP solution circulation pump 1 and the first valve 21, and transfer the high-concentration NMP solution in the air intake space 5 outward;

[0101] Step 3: Open the third valve 41 to transport the NMP mixed solution in the gas-liquid distributor 7 into the air inlet space 5;

[0102] Step 4: Open the first valve 21, and after the modified metal wire mesh filler layer 8 is cleaned by pure water, close the third valve 41;

[0103] Step 5: When the water level in the gas-liquid distributor 7 reaches a preset height, close the first valve 21, and open the second valve 31 and the pure water circulation pump 3 to keep the modified metal wire mesh filler layer 8 moist.

[0104] In the fifth step, the preset height of the water level is not higher than the height of the liquid inlet 77, and its state is referred to Figure 7As shown, it is ensured that during the shutdown wetting stage, the pure water in the storage space is circulated and wetted.

[0105] This embodiment provides a method using the recovery and treatment device described in Example 1, which can obtain a final tail gas with a low NMP content and a high-concentration NMP recovery liquid after treating the NMP-containing waste gas. The modified metal wire mesh filler layer 8 is wetted during the shutdown wetting stage to ensure the hydrophilicity of the modified metal wire mesh filler layer 8, so that the next waste gas recovery and treatment stage can also ensure the absorption effect of NMP in the low-concentration NMP waste gas.

[0106] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A water-soluble waste gas recovery and treatment device, characterized in that: The water-soluble waste gas is low-humidity NMP waste gas; The recycling device comprises: The packing tower comprises, from bottom to top, an air inlet space, an unmodified metal mesh packing layer, a gas-liquid distributor, a modified metal mesh packing layer, a liquid distributor and a first exhaust port; the gas-liquid distributor comprises a liquid storage space, and a gas flow channel and a liquid flow channel arranged in the liquid storage space; the hydrophilicity of the modified metal mesh packing layer is greater than that of the unmodified metal mesh packing layer; A solution circulation pump, one end of which is connected to the air intake space and the other end of which is connected to the gas-liquid distributor, is used to transport the solution in the air intake space to the liquid storage space; A pure water input pipeline is connected to the liquid distributor and is used to inject pure water into the packed tower; a first valve is provided on the pure water input pipeline; A pure water circulation pump, one end of which is connected to the gas-liquid distributor, and the other end of which is connected to the liquid distributor; a second valve is provided between the pure water circulation pump and the gas-liquid distributor; the pure water circulation pump is used to keep the modified metal wire mesh filler layer in a wet state during the shutdown wetting stage; An upper material discharge pipeline, one end of which is connected to the air intake space and the other end of which is connected to the gas-liquid distributor, is used to discharge the liquid in the liquid storage space to the air intake space; a third valve is provided on the upper material discharge pipeline; The static water contact angle of the surface of the unmodified metal wire mesh filler layer is between 70° and 80°; the static water contact angle of the modified metal wire mesh filler layer is between 0° and 15°.

2. The water-soluble waste gas recovery and treatment device according to claim 1 is characterized in that: A heat exchanger is arranged between the solution circulation pump and the gas-liquid distributor.

3. The water-soluble waste gas recovery and treatment device according to claim 1 is characterized in that: The liquid storage space comprises an outer wall and a bottom wall; The gas flow channel comprises a first tube body; the first tube body is connected to the bottom wall, one end of the first tube body extends downward through the bottom wall and a second air inlet is provided at the bottom, and the other end of the first tube body extends upward through the bottom wall and a top is blocked; a second exhaust port is provided on the side of the first tube body, and the second exhaust port is higher than the bottom wall; The liquid flow channel includes a second tube body; the second tube body is connected to the bottom wall, one end of the second tube body extends downward through the bottom wall and a second liquid discharge port is provided at the bottom, and the other end extends upward through the bottom wall and is sealed at the top; a liquid inlet is provided on the side of the second tube body, and the liquid inlet is higher than the bottom wall.

4. The water-soluble waste gas recovery and treatment device according to claim 3 is characterized in that: An overflow port is provided below the second exhaust port.

5. The water-soluble waste gas recovery and treatment device according to claim 3 is characterized in that: The second tube body comprises a main body and an enlarged head; the enlarged head is connected to the end of the main body; the liquid inlet is arranged on the side of the enlarged head; the minimum radial section of the tube body is S1, the total opening area of ​​the liquid inlet is S2, and the maximum radial section of the enlarged head is S3; S1:S2=1:1~2; S1:S3=1:1.3~3.

6. The water-soluble waste gas recovery and treatment device according to claim 3 is characterized in that: The second liquid discharge port is an oblique port, and the angle between the oblique port and the horizontal plane is 45° to 60°.

7. A method for using the recycling device according to any one of claims 1 to 6, characterized in that: The steps include: Waste gas recovery and treatment stage: Open the first valve, and close the second and third valves; The exhaust gas is continuously introduced into the air intake space from the bottom of the tower, and the exhaust gas flows in the direction of the first exhaust port; Pure water is continuously injected into the liquid distributor through the pure water input pipeline, so that the pure water flows through the modified metal wire mesh filler layer to form a low-concentration recovery solution and enters the gas-liquid distributor; A solution circulation pump is used to continuously transport the high-concentration recovery solution in the air intake space to the gas-liquid distributor to mix with the low-concentration recovery solution; The mixed solution in the gas-liquid distributor is made to flow through the unmodified metal wire mesh filler layer to form a high-concentration recovery solution; Shutdown and Wetting Stage: Step 1: Stop the exhaust gas from entering the air intake space; Step 2: close the solution circulation pump and the first valve, and transfer the high-concentration recovery solution in the air intake space to the outside; Step 3: Open the third valve to transport the mixed solution in the gas-liquid distributor into the air inlet space; Step 4: Open the first valve, wait for the pure water to clean the modified metal mesh packing layer, and then close the third valve; Step 5: When the water level in the gas-liquid distributor reaches a preset height, close the first valve, and open the second valve and the pure water circulation pump to keep the modified metal wire mesh filler layer moist.

8. The method according to claim 7, characterized in that In the waste gas recovery stage, the spray density of pure water entering the modified metal wire mesh packing layer is 0.02~0.2m 3 / (m 2 h), the spray density of the mixed solution in the gas-liquid distributor entering the unmodified metal wire mesh packing layer is 0.2~200m 3 / (m 2 h).

9. The method according to claim 8, characterized in that In the waste gas recovery stage, the waste gas is treated by passing through the unmodified metal wire mesh filler layer, and the temperature is 20°C~35°C and the relative humidity is 90%~100%.

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