Treatment system for tail gas containing volatile organic compounds

Abstract

The utility model provides a treatment system for tail gas containing volatile organic compounds. The treatment system comprises a tail gas buffer tank, a fan, a condenser, a recovery liquid storage tank, a membrane adsorption device, a vacuum pump and an exhaust pipe, the tail gas buffer tank is connected with the fan, the fan is connected with the condenser, the condenser is respectively connected with the recovery liquid storage tank and the membrane adsorption device, the membrane adsorption device is respectively connected with the vacuum pump and the exhaust pipe, and the vacuum pump is connected with the tail gas buffer tank. By adopting the treatment system to recover the tail gas containing the volatile organic compounds, the recovery rate of the tail gas containing the volatile organic compounds can be further improved, the production cost is reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] This application relates to the field of exhaust gas treatment technology, and in particular to an exhaust gas treatment system containing volatile organic compounds. Background Technology

[0002] Volatile organic compounds (VOCs) are a significant class of air pollutants requiring strict control. They primarily originate from chemical production processes and are mainly categorized into alkanes, aromatics, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones, and others. For example, the synthesis of esters may generate a mixture of gases (organic waste gas, N2, etc.). This waste gas directly enters the waste gas absorption tower, where separation is difficult. After passing through the absorption tower, acidic gases react with alkaline solutions and remain within the tower, while waste gas containing large amounts of esters is incinerated in a regenerative thermal oxidizer (RTO), causing environmental pollution. However, existing VOC treatment technologies suffer from high energy consumption, poor separation efficiency, and difficulty in achieving emission standards, limiting VOC recovery rates. Therefore, there is an urgent need for a VOC treatment system with low energy consumption and high recovery rates. Utility Model Content

[0003] The purpose of this application is to provide a treatment system for exhaust gas containing volatile organic compounds (VOCs) to improve the recovery rate of VOCs and reduce production costs. The specific technical solution is as follows:

[0004] This application provides a treatment system for exhaust gas containing volatile organic compounds, which includes an exhaust gas buffer tank 1, a fan 2, a condenser 3, a recovery liquid storage tank 4, a membrane adsorption device 5, a vacuum pump 6, and an exhaust pipe 7.

[0005] Wherein, the exhaust gas buffer tank 1 is connected to the fan 2, the fan 2 is connected to the condenser 3, the condenser 3 is connected to the recovery liquid storage tank 4 and the membrane adsorption device 5 respectively, the membrane adsorption device 5 is connected to the vacuum pump 6 and the exhaust pipe 7 respectively, and the vacuum pump 6 is connected to the exhaust gas buffer tank 1.

[0006] The exhaust gas buffer tank 1 is used to store the exhaust gas containing volatile organic compounds. The exhaust gas containing volatile organic compounds is sent to the condenser 3 by the fan 2. The condenser 3 is used to condense the exhaust gas containing volatile organic compounds. The condensed liquid enters the recovery liquid storage tank 4, and the uncondensed gas enters the membrane adsorption device 5. The organic gas generated after adsorption by the membrane adsorption device 5 is sent to the exhaust gas buffer tank 1 by the vacuum pump 6. The residual gas is discharged through the exhaust pipe 7 for back-end treatment.

[0007] In one embodiment of this application, the membrane adsorption device 5 includes a central tube 8 and a membrane adsorption unit 9 wound on the central tube 8; the membrane adsorption unit 9 is formed by stacking a flow guide net 10, a membrane sheet 11 and a spacer 12; the flow guide net 10 is in contact with the outer surface of the central tube 8.

[0008] In one embodiment of this application, the material of the membrane 11 is selected from polymer separation membranes.

[0009] In one embodiment of this application, the polymer separation membrane is selected from at least one of organic permeation membranes, ion exchange membranes, microporous filtration membranes, reverse osmosis membranes, and nanofiltration membranes.

[0010] In one embodiment of this application, the pressure of the fan 2 is 30 kPa to 50 kPa.

[0011] In one embodiment of this application, the condenser 3 is selected from water-cooled, air-cooled, evaporative, or water-spraying types.

[0012] In one embodiment of this application, the condenser 3 is supplied with refrigerant by a refrigeration system, and the refrigerant is selected from water with a temperature of -15°C to 5°C.

[0013] In one embodiment of this application, the exhaust gas containing volatile organic compounds includes volatile organic compounds and inert gases; the volatile organic compounds are selected from at least one of alkane organic compounds, aromatic organic compounds, alkene organic compounds, halogenated hydrocarbon organic compounds, ester organic compounds, aldehyde organic compounds and ketone organic compounds.

[0014] In one embodiment of this application, the volatile organic compound is selected from ester organic compounds.

[0015] In one embodiment of this application, the ester organic compound is selected from at least one of dimethyl carbonate, ethyl methyl carbonate, ethyl acetate, and methyl acetate.

[0016] The beneficial effects of this application are:

[0017] This application provides a system for treating exhaust gas containing volatile organic compounds (VOCs), comprising an exhaust gas buffer tank, a blower, a condenser, a recovery liquid storage tank, a membrane adsorption device, a vacuum pump, and an exhaust pipe. The exhaust gas buffer tank is connected to the blower, the blower is connected to the condenser, the condenser is connected to both the recovery liquid storage tank and the membrane adsorption device, the membrane adsorption device is connected to both the vacuum pump and the exhaust pipe, and the vacuum pump is connected to the exhaust gas buffer tank. Using this treatment system to recover VOC-containing exhaust gas can significantly improve the recovery rate of VOC-containing exhaust gas, reduce production costs, and reduce environmental pollution.

[0018] Of course, any product implementing this application does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0020] Figure 1 This is a schematic diagram of a system for treating exhaust gas containing volatile organic compounds, according to one embodiment of this application.

[0021] Figure 2 This is a schematic diagram of a membrane adsorption device according to one embodiment of this application.

[0022] In the diagram, 1. exhaust gas buffer tank, 2. fan, 3. condenser, 4. recovered liquid storage tank, 5. membrane adsorption device, 6. vacuum pump, 7. exhaust pipe, 8. central tube, 9. membrane adsorption unit, 10. flow guide net, 11. membrane sheet, 12. separator. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0024] like Figure 1 As shown, this application provides a treatment system for exhaust gas containing volatile organic compounds, which includes an exhaust gas buffer tank 1, a fan 2, a condenser 3, a recovery liquid storage tank 4, a membrane adsorption device 5, a vacuum pump 6, and an exhaust pipe 7.

[0025] Wherein, the exhaust gas buffer tank 1 is connected to the fan 2, the fan 2 is connected to the condenser 3, the condenser 3 is connected to the recovery liquid storage tank 4 and the membrane adsorption device 5 respectively, the membrane adsorption device 5 is connected to the vacuum pump 6 and the exhaust pipe 7 respectively, and the vacuum pump 6 is connected to the exhaust gas buffer tank 1.

[0026] The exhaust gas buffer tank 1 is used to store the exhaust gas containing volatile organic compounds. The exhaust gas containing volatile organic compounds is sent to the condenser 3 by the fan 2. The condenser 3 is used to condense the exhaust gas containing volatile organic compounds. The condensed liquid enters the recovery liquid storage tank 4, and the uncondensed gas enters the membrane adsorption device 5. The organic gas generated after adsorption by the membrane adsorption device 5 enters the vacuum pump 6 and is sent to the exhaust gas buffer tank 1. The residual gas is discharged through the exhaust pipe 7 for back-end treatment.

[0027] In this application, the exhaust gas buffer tank 1 is used to store the exhaust gas containing volatile organic compounds. In actual production, the exhaust gas buffer tank 1 can directly collect the exhaust gas generated during production through a gas collection pipeline. In addition, the organic gas adsorbed by the membrane adsorption device 5 is sent into the exhaust gas buffer tank 1 through a vacuum pump 6 for continuous cyclic exhaust gas treatment.

[0028] In one embodiment of this application, the membrane adsorption device 5 includes a central tube 8 and a membrane adsorption unit 9 wound around the central tube 8; the membrane adsorption unit 9 is formed by stacking a flow guide net 10, a membrane sheet 11, and a spacer 12; the flow guide net 10 is in contact with the outer surface of the central tube 8, such as... Figure 2 As shown.

[0029] In this application, the volatile organic exhaust gas enters the membrane adsorption unit 9 through the air intake system. Since the permeation rate of volatile organic compounds in the polymer separation membrane is better than that of non-condensable gases such as nitrogen and water vapor, the organic compounds permeate through the membrane 11 and are separated from the non-condensable gases. The organic exhaust gas is then collected by the guide net 10 and guided into the central tube 8. The non-condensable gases remain outside the membrane. The separator 12 is used to enhance the gas components on the surface of the separation membrane and reduce the uneven distribution of gas concentration.

[0030] In one embodiment of this application, the material of the membrane 11 is selected from polymer separation membranes. The polymer separation membrane has high permeation and diffusion performance; the permeation rate of volatile organic compounds in the polymer separation membrane is ten to tens of times that of conventional inert gases. Therefore, when exhaust gas containing volatile organic compounds passes through the polymer separation membrane with high permeation and diffusion performance, a high-concentration flow of volatile organic compounds is formed on the permeate side, while a flow of organic-poor components enriched by conventional inert gases is formed on the effluent side, thereby achieving gas separation.

[0031] In one embodiment of this application, the polymer separation membrane is selected from at least one of the following: organic permeation membranes, ion exchange membranes, microporous filtration membranes, reverse osmosis membranes, and nanofiltration membranes. Selecting the above polymer separation membranes enables better gas separation.

[0032] In this application, the type of blower 2 is not particularly limited, as long as it can achieve the purpose of this application. For example, a Roots blower can be used.

[0033] In one embodiment of this application, the pressure of the fan 2 is 30 kPa to 50 kPa. For example, the pressure of the fan 2 can be 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, or a range of any two of these values.

[0034] In one embodiment of this application, the condenser 3 is selected from water-cooled, air-cooled, evaporative, or water-spraying types.

[0035] In one embodiment of this application, the condenser 3 is supplied with refrigerant by a refrigeration system, the refrigerant being selected from water with a temperature of -15°C to 5°C. For example, the refrigerant is selected from water with a temperature of -15°C or 5°C.

[0036] In this application, the temperature reached for condensation is not particularly limited, as long as the purpose of this application can be achieved. For example, the tail gas containing volatile organic compounds is transported to the condenser 3, and the tail gas containing volatile organic compounds is condensed to 10~20°C. At this time, the vapor partial pressure of volatile organic compounds in the condenser 3 will greatly exceed its corresponding saturated vapor partial pressure. Approximately 60~80% of the volatile organic compounds are condensed into liquid organic materials and flow into the recovery liquid storage tank 4, while the non-condensable gas reaches the membrane adsorption device 5 along the gas phase outlet.

[0037] In one embodiment of this application, the volatile organic compound (VOC)-containing exhaust gas includes VOCs and an inert gas; the VOCs are selected from at least one of alkane organic compounds, aromatic organic compounds, alkene organic compounds, halogenated hydrocarbon organic compounds, ester organic compounds, aldehyde organic compounds, and ketone organic compounds. The processing system of this application achieves gas separation based on the difference in permeation and diffusion properties between VOCs and conventional inert gases during membrane adsorption.

[0038] Preferably, the volatile organic compounds are selected from ester organic compounds; more preferably, the ester organic compounds are selected from at least one of dimethyl carbonate, ethyl methyl carbonate, ethyl acetate, and methyl acetate. In chemical industrial production, the tail gas from the synthesis of ester organic compounds may produce a mixture of gases (ester organic compounds, N2, etc.), which directly enters the tail gas absorption tower. This part of the tail gas is difficult to separate. After passing through the tail gas absorption tower, the acidic gases can react with the alkaline solution and remain in the tail gas tower, while the tail gas containing a large amount of ester organic compounds enters the RTO for incineration. Using the treatment system of this application, the organic components in the tail gas can be effectively recovered, reducing the pressure of RTO tail gas treatment and reducing environmental pollution.

[0039] Using the treatment system of this application to recover exhaust gas containing volatile organic compounds can further improve the recovery rate of exhaust gas containing volatile organic compounds, reduce production costs, and reduce environmental pollution.

[0040] In one specific embodiment of this application, such as Figure 1 As shown, the treatment system for volatile organic compound (VOC) exhaust gas provided in this application is used to recover VOC-containing exhaust gas. The treatment system includes an exhaust gas buffer tank 1, a fan 2, a condenser 3, a recovery liquid storage tank 4, a membrane adsorption device 5, a vacuum pump 6, and an exhaust pipe 7; Figure 2 As shown, the membrane adsorption device 5 includes a central tube 8 and a membrane adsorption unit 9 wound around the central tube 8. The membrane adsorption unit 9 is formed by stacking a guide net 10, a membrane sheet 11, and a spacer 12, wherein the material of the membrane sheet 11 is selected from membranes that preferentially permeate organic matter. The tail gas generated during the ester organic synthesis process is used as the target. The tail gas temperature is 28~30℃, the pressure is -3kPa, and the inlet flow rate is 118m³. 3 / h, the volatile organic compounds account for 23.7 vol% of the volatile organic compound-containing exhaust gas intake, and the exhaust gas composition is shown in Table 1. The steps are as follows:

[0041] Table 1

[0042]

[0043] The tail gas containing volatile organic compounds (VOCs) in the tail gas buffer tank 1 is transported to the condenser 3 by the blower 2. The cooling capacity of the condenser 3 comes from -15℃ chilled water. At this point, the tail gas containing VOCs is condensed to about 5~10℃. The partial pressure of the tail gas containing VOCs in the condenser 3 will exceed its corresponding saturated vapor pressure, causing liquefaction. Most of the ester organic gases condense into liquid, and the condensed liquid enters the recovery liquid storage tank 4. At this point, the concentration of ester gases in the non-condensable gas can be reduced to about 6~8 vol%, which then enters the membrane adsorption device 5. In the membrane adsorption device 5, taking advantage of the difference in the permeation effect of ester gases in the polymer separation membrane, the ester gases pass through the membrane 11 before nitrogen, water, etc., and enter the central tube 8 for collection. Finally, they enter the tail gas buffer tank 1 again for recirculation through the vacuum pump 6. The residual gas in the membrane adsorption device 5 enters the downstream treatment through the exhaust pipe 7. The gas composition of the membrane adsorption device is shown in Table 2.

[0044] Table 2

[0045]

[0046] Membrane system inlet: The organic matter content in the exhaust gas intake is: 118 × 23.7% = 27.97 Nm³. 3 / h; Organic matter recovery rate: 27.97 × 70% (first step condensation rate) = 19.57 Nm³ 3 / h; The volume fraction of organic matter at the membrane system inlet is: (27.97-19.57) / [118-27.97+(27.97-19.57)]=8.5%;

[0047] Excess gas: The amount of gas other than organic matter that did not pass through the membrane and was not adsorbed is: 118 × (1 - 23.7%) × 80% (Amount of gas other than organic matter that did not pass through the membrane and was not adsorbed) = 72 Nm 3 / h, the amount of organic matter in the residual gas is: 72 / (1-0.5%)-72=0.36Nm 3 / h, the total residual gas is: 72 + 0.36 = 72.36 Nm³ 3 / h;

[0048] Membrane system outlet: 98.43 - 72.36 = 26.07 Nm 3 / h, organic matter volume fraction = (98.43 × 8.5% - 72.36 × 0.5%) / 26.07 = 30.58%.

[0049] The results above show that using the treatment system of this application to recover exhaust gas containing volatile organic compounds can improve the recovery rate of exhaust gas containing volatile organic compounds, up to about 98%, and reduce production costs.

[0050] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A treatment system for exhaust gas containing volatile organic compounds, comprising an exhaust gas buffer tank (1), a fan (2), a condenser (3), a recovery liquid storage tank (4), a membrane adsorption device (5), a vacuum pump (6), and an exhaust pipe (7). in, The exhaust gas buffer tank (1) is connected to the fan (2), the fan (2) is connected to the condenser (3), the condenser (3) is connected to the recovery liquid storage tank (4) and the membrane adsorption device (5) respectively, the membrane adsorption device (5) is connected to the vacuum pump (6) and the exhaust pipe (7) respectively, and the vacuum pump (6) is connected to the exhaust gas buffer tank (1). The tail gas buffer tank (1) is used to store the tail gas containing volatile organic compounds. The tail gas containing volatile organic compounds is sent into the condenser (3) by the fan (2). The condenser (3) is used to condense the tail gas containing volatile organic compounds. The condensed liquid enters the recovery liquid storage tank (4). The uncondensed gas enters the membrane adsorption device (5). The organic gas generated after adsorption by the membrane adsorption device (5) is sent into the tail gas buffer tank (1) by the vacuum pump (6). The residual gas is discharged through the exhaust pipe (7) for back-end treatment.

2. The processing system according to claim 1, wherein, The membrane adsorption device (5) includes a central tube (8) and a membrane adsorption unit (9) wound on the central tube (8); the membrane adsorption unit (9) is formed by stacking a flow guide net (10), a membrane sheet (11) and a spacer net (12); the flow guide net (10) is in contact with the outer surface of the central tube (8).

3. The processing system according to claim 2, wherein, The material of the membrane (11) is selected from polymer separation membranes.

4. The processing system according to claim 3, wherein, The polymer separation membrane is selected from at least one of the following: organic permeation membranes, ion exchange membranes, microporous filtration membranes, reverse osmosis membranes, and nanofiltration membranes.

5. The processing system according to claim 1, wherein, The pressure of the fan (2) is 30 kPa ~ 50 kPa.

6. The processing system according to claim 1, wherein, The condenser (3) is selected from water-cooled, air-cooled, evaporative, or water-spraying types.

7. The processing system according to claim 1, wherein, The condenser (3) is supplied with refrigerant by the refrigeration system, and the refrigerant is selected from water with a temperature of -15℃ to 5℃.

8. The processing system according to claim 1, wherein, The exhaust gas containing volatile organic compounds includes volatile organic compounds and inert gases; the volatile organic compounds are selected from at least one of alkane organic compounds, aromatic organic compounds, alkene organic compounds, halogenated hydrocarbon organic compounds, ester organic compounds, aldehyde organic compounds and ketone organic compounds.

9. The processing system according to claim 1, wherein, The volatile organic compounds are selected from ester organic compounds.

10. The processing system according to claim 9, wherein, The ester organic compound is selected from at least one of dimethyl carbonate, ethyl methyl carbonate, ethyl acetate, and methyl acetate.

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