An adsorption process for DCM waste gas and its dedicated adsorption system

Abstract

The present invention discloses an adsorption process for DCM waste gas and its dedicated adsorption system, belonging to the technical field of environmental protection. The adsorption system of the present invention includes a waste gas adsorption system, a resin desorption system, a desorbed gas recovery system, a resin cooling and drying system, a wastewater treatment system, and a safety prevention and control system; between each system, the automatic control system is used to separately control each adsorber to sequentially perform the adsorption-desorption-regeneration process alone, realizing the full-automatic integration of waste gas adsorption-desorption-regeneration-wastewater treatment. Moreover, after the device runs continuously for 7200 h, it can still maintain a purification efficiency of 99%, the resin loss rate is only 3.0%, the operating cost is reduced by more than 65%, achieving the dual up-to-standard discharge of DCM waste gas and wastewater, and having remarkable environmental and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to an adsorption system for adsorbing dichloromethane. Background Art

[0002] Dichloromethane (DCM) has the advantages of low flammability and strong solubility, and is widely used in the pharmaceutical, chemical and semiconductor industries. However, it has a low boiling point and is very easy to volatilize into the surrounding environment. If it is not controlled, it will cause human poisoning on the one hand, and on the other hand, it will decompose under the action of light to produce phosgene and carbon monoxide, thereby destroying the ozone layer. The "List of New Pollutants under Key Control (2023 Edition)" (Ministry of Ecology and Environment Order No. 28) announced by the Ministry of Ecology and Environment on December 29, 2022 listed DCM as one of the new pollutants that require key control. The "Stockholm Convention" also lists DCM as one of the 12 persistent organic pollutants that are prioritized for treatment and control. Therefore, the control of DCM has become one of the environmental problems that need to be solved urgently.

[0003] Common DCM treatment technologies mainly include condensation method, absorption method, combustion method, biological treatment method, adsorption method, etc. Condensation method: The condensation method is to use a temperature below the boiling point to condense the target pollutants in the waste gas into a liquid, so as to achieve a certain removal effect, and the condensed liquid can often be reused in production. Generally, this method can be used for waste gas with small air volume and high concentration. However, the concentration of organic matter in the waste gas after condensation is still relatively high, and further treatment is required to meet the emission requirements. According to relevant engineering experience, for DCM waste gas, it has a better condensation effect at -70°C, but at this time, coolants such as liquid nitrogen need to be used for condensation, and the investment cost is often expensive, and many small and medium-sized chemical enterprises generally cannot afford it. Absorption method: The absorption method can be divided into chemical absorption and physical absorption. Physical absorption generally targets organic pollutants with good solubility, and chemical absorption can be divided into acid absorption, base absorption, redox absorption, etc. In actual engineering applications, one or more chemical absorption methods are often used to treat specific waste gas properties. If the absorption method is used alone for purification, the removal effect of poorly soluble DCM pollutants is not ideal. Even if oxidation absorption is carried out by adding oxidants and other measures, its ability to degrade DCM is not very strong, and generally cannot achieve the expected treatment goal, and the DCM degradation rate is relatively low. Incineration method: Also known as thermal oxidation method and thermal combustion method, it is a method of decomposing organic pollutants into harmless substances by using high temperature. The incineration method is a relatively effective method for treating organic pollutants. After incineration treatment, generally, a relatively ideal treatment effect can be achieved. However, if the incineration temperature and residence time are not controlled well, resulting in incomplete combustion, more toxic substances will be produced. Especially for chlorine-containing organic compounds, more toxic substances such as dioxins will be produced. For DCM, the biggest obstacle to the incineration method is that highly toxic pollutants such as dioxins are easily produced after incineration. Although the research on incineration in the United States is relatively in-depth, it is found that as long as the incineration temperature is reached, the residence time is reached, and the remaining oxygen content in the tail gas is reached, the generation of dioxins can be effectively curbed. However, in actual operation, due to the fluctuating concentration of the waste gas, it is difficult to accurately and stably control the incineration process. In addition, specifications such as Safety Technical Requirements for Regenerative Thermal Oxidizer System (DB32 / T 4700-2024) and Technical Specifications for Industrial Organic Waste Gas Treatment Engineering by Regenerative Thermal Oxidation Method (HJ 1093-2020) do not recommend using a regenerative thermal oxidizer (RTO) to treat chlorine-containing organic waste gas. Biological treatment method: Biological treatment for purifying organic waste gas mainly uses the degradation effect of microorganisms to convert the organic substances in the waste gas into simple inorganic substances (such as CO2, water, etc.) and cell components. For the treatment of organic waste gas, a commonly used device is a biological trickling filter, but the domestication period of microorganisms is relatively long, and microorganisms are relatively sensitive to the fluctuations of the waste gas. Compared with other methods, this process has the characteristics of low operating cost, good safety, and no secondary pollution, and is suitable for the treatment of low and medium concentration organic waste gas.However, DCM has high biological toxicity, is insoluble in water, and is difficult to be degraded by microorganisms. Therefore, if the biological method is used to treat DCM, a longer domestication period is often required. In addition, if the concentration of DCM waste gas fluctuates greatly, it will also greatly affect the growth and degradation effect of microorganisms. Adsorption method: The adsorption method uses a porous solid adsorption material as an adsorbent to adsorb DCM on the surface of the adsorbent to achieve the purpose of removal. After adsorption, the adsorbed DCM is generally removed by heat treatment to regenerate the adsorbent for repeated use. The adsorption method has the advantages of simple process, high adsorption efficiency, low energy consumption, etc., and is widely used in DCM treatment. Commonly used DCM adsorbents include activated carbon, molecular sieve, and adsorption resin.

[0004] Due to its large specific surface area, good chemical stability and low price, activated carbon has a high adsorption capacity for DCM and is a widely used adsorbent. However, activated carbon is flammable during the DCM adsorption process, its pores are easily blocked, and regeneration is difficult, which restricts the application of activated carbon in DCM adsorption. Molecular sieve has good selectivity, thermal stability and relatively suitable price for DCM adsorption, and is widely sourced, making it an adsorbent with great application prospects. However, its moisture resistance is relatively poor and needs further improvement.

[0005] Adsorption resin is a new type of polymer material with concentration separation and adsorption functions, mainly used for the adsorption of organic pollutants in water. In recent years, domestic and foreign scholars have also applied adsorption resin to the adsorption treatment of gas pollutants. Differentiated modification of traditional resin as the matrix to prepare new resins with special applications suitable for different industrial production needs can not only optimize the resin structure and improve the adsorption efficiency, but also expand the application field of adsorption resin. It has been widely recognized in the research field and is also a hot direction for the in-depth study of adsorption theory in the future. A large number of literature materials and engineering operation data show that although traditional adsorption resin has a large specific surface area and good water resistance, its adsorption capacity for DCM is low, and there is less research on the modification of adsorption resin for DCM adsorption.

[0006] Therefore, how to use modified resin in combination with specific processes to adsorb DCM and meet national standards after adsorption treatment has become an urgent problem to be solved. Summary of the Invention

[0007] The first object of the present invention is to propose an adsorption process for DCM waste gas, which can realize the full-automatic integration operation of DCM waste gas adsorption-desorption-regeneration-wastewater treatment, reduce the loss of adsorption resin and the waste of energy, and achieve the dual standard discharge of DCM waste gas and wastewater.

[0008] The second object of the present invention is to provide an adsorption system for DCM waste gas. Through the design of pipelines and valves, each device can operate independently, greatly improving the adsorption efficiency of DCM.

[0009] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0010] An adsorption process for DCM waste gas includes a waste gas adsorption process, a resin desorption process, a desorbed gas recovery process, and a wastewater treatment process. The DCM waste gas first undergoes adsorption purification through the waste gas adsorption system, and the purified gas is discharged from the waste gas adsorption system. When the adsorption capacity of the waste gas adsorption system reaches saturation, the resin desorption process is carried out to desorb and remove the adsorbed DCM in the waste gas adsorption system, restoring the normal state of the waste gas adsorption system. The desorbed DCM enters the desorbed gas recovery system, where solid-liquid separation is achieved, and the separated solid DCM is recycled. The separated wastewater enters the wastewater treatment process, and after treatment in the wastewater treatment process, the tail water can be directly discharged from the system, realizing the adsorption, desorption, and regeneration processes of DCM waste gas.

[0011] The concentration of the DCM waste gas before treatment is not less than 10000 mg / m 3 ; the concentration of the purified gas after treatment is not higher than 60 mg / m 3 .

[0012] An adsorption system for DCM waste gas includes a waste gas adsorption system, a resin desorption system, a desorbed gas recovery system, a resin cooling and drying system, and a wastewater treatment system.

[0013] Furthermore, the waste gas adsorption system includes resin adsorber a and resin adsorber b. The bottoms of resin adsorber a and resin adsorber b are respectively provided with steam inlet valve a and steam inlet valve b; high-efficiency gas distributors a and b are respectively arranged at the bottom of the inner cavities of resin adsorber a and resin adsorber b; the middle parts of the inner cavities of resin adsorber a and resin adsorber b are filled with modified adsorption resin; the waste gas adsorption system includes resin adsorber a and resin adsorber b. The tops of resin adsorber a and resin adsorber b are respectively provided with outlet valve a and outlet valve b; high-efficiency gas distributors a and b are respectively arranged at the bottom of the inner cavities of resin adsorber a and resin adsorber b; the middle parts of the inner cavities of resin adsorber a and resin adsorber b are filled with modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR).

[0014] Further, the resin desorption system includes a resin adsorber a and a resin adsorber b. The tops of the resin adsorber a and the resin adsorber b are respectively provided with a saturated steam inlet valve a and a steam inlet valve b; high-efficiency steam distributors a and b are respectively arranged at the top of the inner cavities of the resin adsorber a and the resin adsorber b; desorbed gas discharge valves a and b are respectively arranged at the bottoms of the resin adsorber a and the resin adsorber b.

[0015] Further, the desorbed gas recovery system includes a high-efficiency condenser a, a high-efficiency condenser b, a high-efficiency condenser c, a condensate stratification tank, a recovered solvent receiving tank and a wastewater receiving tank that are connected in sequence; the condensate gases of the high-efficiency condenser a, the high-efficiency condenser b, the high-efficiency condenser c, the condensate stratification tank, the recovered solvent receiving tank and the wastewater receiving tank are connected to the inlet of an exhaust gas induced draft fan through pipelines.

[0016] Further, the resin cooling and drying system includes a resin adsorber a, a resin adsorber b and a water ring vacuum pump.

[0017] Further, the wastewater treatment system includes a resin adsorber c; automatic switching valves a and b are arranged at the top of the resin adsorber c; automatic switching valves d and c are arranged at the bottom of the resin adsorber c; a high-efficiency steam distributor c is arranged at the top of the inner cavity of the resin adsorber c, and modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) is filled in the middle.

[0018] Further, the preparation method of the (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) modified adsorption resin is as follows: impregnate the adsorption resin in a metal ion solution, wash it with water until the pH = 6-7, and obtain the modified adsorption resin loaded with metal ions after drying; put MWCNTs into ultrapure water, and prepare a MWCNTs dispersion liquid by ultrasonic dispersion; then immerse the modified adsorption resin loaded with metal ions in the MWCNTs dispersion liquid and dry it again to obtain the (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) modified adsorption resin.

[0019] Further, the metal ion solution is an aqueous solution of AlCl3.

[0020] Further, in the modified adsorption resin loaded with metal ions, the metal ion loading amount is 5 wt.%.

[0021] Further, in the (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) modified adsorption resin, the MWCNTs loading amount is 2 wt.%.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] 1) The adsorption system disclosed in the present invention realizes the full-automatic integrated operation of DCM waste gas adsorption-desorption-regeneration-wastewater treatment, and the purification efficiency can still be maintained at 99% after the device has been continuously operated for 7200 h; the resin loss rate is only 3.0%, which is lower than the technical requirement of "annual resin loss rate of 5%" in the "Engineering Technical Specification for Industrial Organic Waste Gas Treatment by Resin Adsorption Method" (T / CPCIF 0175-2021).

[0024] 2) The saturated adsorption capacity of the modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) prepared in the present invention for DCM is increased from 258.77 mg / g of the unmodified adsorption resin to 644.57 mg / g (the increase rate is as high as 149.09%), and the 24-hour dynamic continuous adsorption efficiency is increased from 84.98% of the unmodified adsorption resin to 99.35%; the adsorption cycle to meet the up-to-standard discharge is extended from 2 h of the unmodified adsorption resin to 14 h.

[0025] 3) The modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) and its adsorption system disclosed in the present invention can reduce the DCM waste gas with an emission concentration of up to 10000 mg / m 3 to less than 60 mg / m 3 after adsorption treatment, meeting the current strictest "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021) without further treatment.

[0026] 4) The modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) and its adsorption system disclosed in the present invention can reduce the DCM wastewater with a COD concentration of up to 5000 mg / L to 50 mg / L after adsorption treatment, and the COD index of the tail water meets the first-class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB 18918-2002) without further treatment.

[0027] 5) The operating cost of the adsorption system disclosed in the present invention is reduced from 3754 yuan / d of the unmodified resin and the original device to 1294 yuan / d, and the operating cost is saved by more than 65%, achieving significant environmental and economic benefits. Description of the Drawings

[0028] Figure 1 It is the process flow chart of the laboratory resin adsorption and desorption device for DCM.

[0029] Figure 2 It is the breakthrough curve of DCM adsorption on the single-metal modified adsorption resin.

[0030] Figure 3 It is the breakthrough curve of DCM adsorption on the double-metal modified adsorption resin.

[0031] Figure 4 It is the adsorption breakthrough curve of DCM on the modified adsorption resin of multi-walled carbon nanotubes (MWCNTs).

[0032] Figure 5 It is the trend chart of continuous monitoring of DCM concentration (counted as C) at the inlet and outlet of the waste gas of the unmodified resin adsorption and desorption device and the purification efficiency.

[0033] Figure 6 It is the trend chart of continuous monitoring of DCM concentration (counted as C) at the inlet and outlet of the waste gas of the modified resin adsorption and desorption device and the purification efficiency.

[0034] Figure 7 It is the flow chart of the DCM waste gas adsorption and desorption treatment system.

[0035] Among them, 1. Inlet valve; 2. Bypass valve; 3. DCM waste gas inlet valve a; 4. Outlet valve a; 5. DCM waste gas inlet valve b; 6. Outlet valve b; 7. Steam inlet valve a; 8. Steam inlet valve b; 9. Desorber discharge valve a; 10. Steam inlet valve c; 11. Steam inlet valve d; 12. Desorbed gas discharge valve b; 13. Automatic switching valve a; 14. Automatic switching valve b; 15. Automatic switching valve c; 16. Automatic switching valve d; 17. Exhaust gas induced draft fan; 18. Surface cooler; 19. High-efficiency condenser a; 20. High-efficiency condenser b; 21. High-efficiency condenser c; 22. Resin adsorber a; 23. Resin adsorber b; 24. Resin adsorber c; 25. Water ring vacuum pump; 26. Waste water transfer pump; 27. Solvent transfer pump; 28. High-efficiency steam distributor a; 29. High-efficiency steam distributor b; 30. High-efficiency steam distributor c; 31. High-efficiency gas distributor a; 32. High-efficiency gas distributor b; 33. Condensate stratification tank; 34. Recovered solvent receiving tank; 35. Waste water receiving tank; A. Pressure monitoring system; B. Temperature monitoring system; C. Flow monitoring system. Specific embodiments

[0036] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following specific embodiments are used to make a detailed description of the specific implementation manners of the present invention.

[0037] The following embodiments adopt the laboratory resin adsorption and desorption device as Figure 1As shown in the figure, the standard air flowing out of the standard air cylinder is divided into two paths. One path controls the gas flow rate Q1 through a mass flow controller and enters the constant-temperature bubbling device filled with DCM from the top. The other path controls the gas flow rate Q2 through a mass flow controller. The two paths of gas are fully mixed in the mixing device, and the temperature in the bubbling device is kept constant. Different concentrations of DCM gas can be obtained by adjusting the magnitudes of Q1 and Q2. The resin adsorption column used has a cylindrical structure with an inner diameter of 100 mm, a height of 1000 mm, a resin layer filling height of 450 mm, and a cross-sectional area of the resin layer of 0.00785 m 2 , the resin filling amount is 3.5 L, the waste gas treatment flow rate is 4.2 m 3 / h, the cross-sectional over-flow gas velocity is 0.15 m / s, the gas residence time is 3 s, and the DCM concentration is controlled at 7000 mg / m 3 .

[0038] The test methods for the BET specific surface area, micropore volume, total pore volume, balling rate after grinding, and wet apparent density of the resin adsorbent refer to the "Technical Specification for Industrial Organic Waste Gas Treatment Engineering by Resin Adsorption Method" (T / CPCIF 0175-2021). A portable VOCs monitoring instrument is used to measure the DCM concentration (denoted as C) at the inlet and outlet of the experimental device. The calculation formula for the adsorption efficiency at the inlet and outlet of the experimental device is as follows:

[0039]

[0040] In the formula: C0 (mg / m 3 ) and C t (mg / m 3 ) are the DCM concentrations at the inlet and outlet of the experimental device respectively, and Q0 (Nm 3 / h) and Q t (Nm 3 / h) are the gas flow rates at the inlet and outlet of the experimental device respectively.

[0041] Example 1

[0042] An adsorption process for DCM waste gas includes a waste gas adsorption process, a resin desorption process, a desorbed gas recovery process, and a wastewater treatment process; the specific process is as follows:

[0043] Open the intake valve 1, DCM waste gas intake valve a 3 and DCM waste gas intake valve b 5. The DCM waste gas passes through the inlet pipeline, is cooled and dewatered by the surface cooler 18, and then is sent into the resin adsorber a 22 and resin adsorber b 23 by the waste gas induced draft fan 17 for adsorption treatment. The high-efficiency gas distributors a 31 and b 32 provided at the bottoms of the resin adsorber a 22 and resin adsorber b 23 can evenly distribute the DCM waste gas on the cross-section of the resin bed layer to ensure high-efficiency adsorption. The purified gas meeting the "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021) is discharged to the atmosphere through the outlet valves a 4 and b 6 at the tops of the resin adsorber a 22 and resin adsorber b 23.

[0044] As the adsorption continues, the resin adsorber with saturated adsorption capacity will enter the desorption process. At this time, open the steam intake valve b 8 and steam intake valve d 11. The saturated steam is sprayed onto the resin bed layer of the corresponding resin adsorber from top to bottom through the high-efficiency steam distributors a 28 and b 29, desorbing the DCM adsorbed on the resin bed layer. The desorbed gas-liquid mixture containing DCM enters the desorbed gas recovery system through the desorber discharge valve a 9 and desorbed gas discharge valve b 12 for the recovery process of the desorbed gas.

[0045] As the desorbed gas recovery process progresses, the desorbed gas successively passes through the connected high-efficiency condensers a 19, b 20, c 21 to reach the condensate separation tank 33. In the condensate separation tank 33, the desorbed gas-liquid mixture containing DCM is condensed into a liquid state and physically separated into DCM and water in the separation tank. The DCM enters the solvent receiving tank 34 and is then transported to the workshop for reuse through the solvent transfer pump 27, while the wastewater enters the wastewater receiving tank 35 and is then transported to the wastewater treatment system through the wastewater transfer pump 26. Among them, the condensate gases of the high-efficiency condensers a 19, b 20, c 21, condensate separation tank 33, recovered solvent receiving tank 34, and wastewater receiving tank 35 are connected to the inlet of the waste gas induced draft fan (17) through pipelines.

[0046] As more and more wastewater is transported to the wastewater treatment system, at this time, open the automatic switching valve a 13, and the wastewater enters the resin adsorber c 24 from top to bottom. The high-efficiency steam distributor c 30 is provided at the top of the inner cavity of the resin adsorber c 24, and the middle is filled with the modified system resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR). Through the adsorption and purification of the resin, the wastewater is purified. Open the automatic switching valve d 16, and the purified water meeting the standard is discharged from the system through the pipeline.

[0047] Example 2

[0048] An adsorption system for DCM waste gas, as Figure 7 shown, includes a waste gas adsorption system, a resin desorption system, a desorbed gas recovery system, a resin cooling and drying system, a wastewater treatment system, and a safety prevention and control system.

[0049] The waste gas adsorption system includes a resin adsorber a 22 and a resin adsorber b 23. The tops of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with an outlet valve a 4 and an outlet valve b 6; the bottoms of the inner cavities of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with a high-efficiency gas distributor a 31 and a high-efficiency gas distributor b 32; the middle parts of the inner cavities of the resin adsorber a 22 and the resin adsorber b 23 are filled with modified adsorption resin; the waste gas adsorption system includes a resin adsorber a 22 and a resin adsorber b 23. The tops of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with an outlet valve a 4 and an outlet valve b 6; the bottoms of the inner cavities of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with a high-efficiency gas distributor a 31 and a high-efficiency gas distributor b 32; the middle parts of the inner cavities of the resin adsorber a 22 and the resin adsorber b 23 are filled with modified adsorption resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR).

[0050] The working process of the waste gas adsorption system is as follows: The DCM waste gas after being cooled and dewatered by the surface cooler is sent into the resin adsorber a and the resin adsorber b through the DCM waste gas inlet valve a and the DCM waste gas inlet valve b by the waste gas induced draft fan for adsorption treatment. The high-efficiency gas distributors arranged at the bottom of the adsorber can evenly distribute the DCM waste gas on the cross-section of the resin bed layer to ensure high-efficiency adsorption. The purified gas meeting the "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021) is discharged to the atmosphere through the outlet valve at the top of the adsorber.

[0051] The resin desorption system includes a resin adsorber a 22 and a resin adsorber b 23. The tops of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with a saturated steam inlet valve a 7 and a steam inlet valve b 8; the tops of the inner cavities of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with a high-efficiency steam distributor a 28 and a high-efficiency steam distributor b 29; the bottoms of the resin adsorber a 22 and the resin adsorber b 23 are respectively provided with a desorbed gas discharge valve a 9 and a desorbed gas discharge valve b 12.

[0052] The working process of the resin desorption system is as follows: The adsorber that has reached saturation enters the desorption process. The saturated steam is sprayed into the resin bed layer from top to bottom through the high-efficiency steam distributor to desorb the DCM adsorbed on the resin bed layer. The gas-liquid mixture containing DCM desorbed enters the desorbed gas recovery system through the desorbed gas discharge valve.

[0053] The desorbed gas recovery system includes a high-efficiency condenser a 19, a high-efficiency condenser b 20, a high-efficiency condenser c 21, a condensate stratification tank 33, a recovered solvent receiving tank 34, and a wastewater receiving tank 35 that are connected in sequence; the condensate gases of the high-efficiency condenser a 19, the high-efficiency condenser b 20, the high-efficiency condenser c 21, the condensate stratification tank 33, the recovered solvent receiving tank 34, and the wastewater receiving tank 35 are connected to the inlet of the exhaust gas induced draft fan 17 through pipelines.

[0054] The working process of the desorbed gas recovery system is as follows: The desorbed DCM gas-liquid mixture containing DCM is condensed into a liquid state through three-stage condensation and refrigeration, and the physical stratification of DCM and water is achieved in the stratification tank. After DCM enters the solvent recovery tank, it is transported to the workshop for reuse through a solvent transfer pump, and the wastewater enters the wastewater collection tank and is then transported to the wastewater treatment system through a wastewater transfer pump.

[0055] The resin cooling and drying system includes a resin adsorber a 22, a resin adsorber b 23, and a water ring vacuum pump 25. The resin cooling and drying system sucks the DCM that is not completely desorbed from the resin bed layer and the remaining DCM gas-liquid mixture in the adsorber cavity to the desorbed gas recovery system through the water ring vacuum pump, so as to achieve the purpose of reducing the temperature of the resin bed layer after desorption.

[0056] The wastewater treatment system includes a resin adsorber c 24; an automatic switching valve a 13 and an automatic switching valve b 14 are arranged at the top of the resin adsorber c 24; an automatic switching valve d 16 and an automatic switching valve c 15 are arranged at the bottom of the resin adsorber c 24; a high-efficiency steam distributor c 30 is arranged at the top of the inner cavity of the resin adsorber c 24, and a modified system resin (MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) is filled in the middle.

[0057] The working process of the wastewater treatment system is as follows: The DCM wastewater is fed into the adsorber from top to bottom through a wastewater transfer pump for adsorption treatment, and the tail water with COD meeting the first-class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB 18918-2002) is discharged to the external environment through the outlet valve at the bottom of the adsorber.

[0058] The safety prevention control system includes temperature, pressure and flow monitoring, high-temperature alarm during the adsorption process, low-temperature alarm during the desorption process, and overpressure protection for the adsorber. The temperature, pressure and flow monitoring includes monitoring of the temperature B of the condenser outlet pipeline, the temperature B and pressure A of the resin bed, the temperature B, pressure A and flow C of the DCM waste gas / purified gas, the temperature B, pressure A and flow C of the saturated water vapor, and the temperature B, pressure A and flow C of the fire water; the high-temperature alarm during the adsorption process is to emergently start the fire water spray cooling when the monitored temperature of the resin bed exceeds 83°C during the adsorption process; the low-temperature alarm during the desorption process is to emergently start the alarm signal for insufficient steam temperature when the monitored temperature of the resin bed is lower than 90°C during the desorption process; the overpressure protection for the adsorber is to automatically open the pressure relief when the monitored pressure in the adsorption tank exceeds 0.1 MPa, and at the same time close 1 and open 2. The induced draft fan, control valves, detection devices and control devices involved in the system are connected, and the whole process is automatically controlled through the control system.

[0059] Example 3

[0060] The preparation method of the adsorption resin (AR) is as follows:

[0061] (1) Polymerization reaction: Styrene, 1,2-distyrene, water, benzoyl peroxide (initiator), and liquid paraffin (pore-forming agent) are put into the polymerization reactor and stirred evenly at room temperature; the dispersants cellulose, gelatin, and anti-emulsifier methylene blue are fully dissolved in water and then put into the above polymerization reactor. First, the temperature is raised to 80°C and kept warm for 4 h, then the temperature is raised to 85°C and kept warm for 4 h, and then the temperature is raised to 98°C and kept warm for 4 h. Finally, the temperature is lowered to 30°C to end the reaction. After the reaction is completed, the polymer is separated and washed with water, and the polymer with the pore-forming agent is sent to the drying process, and dried at 60°C for 1 h to obtain an intermediate; the intermediate is sent to the extraction column, and the pore-forming agent liquid paraffin in the intermediate is extracted multiple times with the extractant methylal. After the extraction is completed, it is rinsed multiple times with water. The rinsed intermediate is dried at 80°C for 10 h to obtain semi-finished product I with a water content of less than 1%;

[0062] (2) Chlorination reaction: At room temperature, semi-finished product I, chloromethyl ether and water are put into the chlorination reactor and stirred for 2 h to make them mix evenly. Under stirring, the catalyst ferric chloride is put in, and the group reaction is carried out at 45°C; after the reaction is completed, the temperature is lowered to room temperature. After filtering out the mother liquor, it is rinsed multiple times with methanol and water, and after rinsing well, it is dried at 80°C for 10 h to obtain semi-finished product II with a water content of less than 1%;

[0063] (3) Post-crosslinking: Semi-finished product II and the swelling agent dichloroethane are put into the crosslinking reactor, mixed and stirred for swelling for 5 h, and then aluminum trichloride is put in. The temperature is raised to 75°C for post-crosslinking reaction for 24 h. After distilling out dichloroethane, water is added for rinsing, and the water washing is carried out until the pH = 6 - 7, and then dried at 80°C for 10 h to obtain the adsorption resin.

[0064] Preparation method of single metal ion modified adsorption resin, the steps are as follows:

[0065] (1) Preparation of single metal solution: Prepare aqueous solutions of AlCl3, LiCl, MgCl2, FeCl3, CaCl2 and AgNO3 with a concentration of 0.1 mol / L respectively;

[0066] (2) Modification by impregnation method: At room temperature, immerse the adsorption resin products in the different metal salt solutions prepared in step (1) respectively. After 24 h, wash with water until the pH = 6 - 7, and then carry out drying treatment at 80 °C for 10 h to obtain single metal modified adsorption resin. Control the impregnation times of the adsorption resin by comparing the mass of the adsorption resin before and after impregnation to obtain single metal ion modified adsorption resin with a metal ion loading ratio of 5 wt.% (Al(Ⅲ)-AR, Li(Ⅰ)-AR, Mg(Ⅱ)-AR, Ca(Ⅱ)-AR, Fe(Ⅲ)-AR, Ag(Ⅰ)-AR).

[0067] Example 4

[0068] Preparation method of double metal ion modified adsorption resin, the steps are as follows:

[0069] (1) Preparation of double metal solution: First, prepare aqueous solutions of AlCl3, LiCl and MgCl2 with a concentration of 0.2 mol / L respectively. Then, mix the aqueous solutions of AlCl3 and LiCl, AlCl3 and MgCl2, LiCl and MgCl2 in equal volumes to prepare double metal solutions with a metal ion molar ratio of 1:1;

[0070] (2) Modification by impregnation method: At room temperature, immerse the adsorption resin products in the different double metal solutions prepared in step (1) respectively. After 24 h, wash with water until the pH = 6 - 7, and then carry out drying treatment at 80 °C for 10 h to obtain double metal modified adsorption resin. Control the impregnation times of the adsorption resin by comparing the mass of the adsorption resin before and after impregnation to obtain double metal ion modified adsorption resin with a loading ratio of 5 wt.% (Li(Ⅰ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Li(Ⅰ)-AR).

[0071] Example 5

[0072] Preparation method of multi-walled carbon nanotubes (MWCNTs) modified adsorption resin, the steps are as follows:

[0073] First, the unmodified adsorption resin (AR) and the bimetallic ion-modified adsorption resins (Li(Ⅰ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Li(Ⅰ)-AR) were soaked in methanol solution for 24 h; MWCNTs were put into ultrapure water, and a 5 mg / mL MWCNTs dispersion was prepared by ultrasonic dispersion; the above adsorption resins were immersed in the MWCNTs dispersion, and ultrasonic treatment was carried out at room temperature for 8 h to fix MWCNTs in the pores of the adsorption resin. Then, the excess MWCNTs on the surface of the adsorption resin were removed with ultrapure water, and then washed continuously with water until the pH = 6 - 7, and then dried at 80 °C for 10 h to obtain MWCNTs-modified adsorption resins; the number of ultrasonic treatments of the adsorption resin was controlled by comparing the mass of the adsorption resin before and after ultrasonic treatment, and MWCNTs-modified adsorption resins with a MWCNTs loading ratio of 2 wt.% (MWCNTs-AR, MWCNTs-Mg(Ⅱ) / Li(Ⅰ)-AR, MWCNTs-Mg(Ⅱ) / Al(Ⅲ)-AR, MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR) were obtained.

[0074] Example 6

[0075] The effects of single metal ion (Li(Ⅰ), Ca(Ⅱ), Al(Ⅲ), Fe(Ⅲ), Mg(Ⅱ), Ag(Ⅰ)) modification on the adsorption performance of hypercrosslinked adsorption resin (AR) are shown in Table 1 below.

[0076] Table 1 Relevant parameters such as the pore structure of single metal ion-modified adsorption resins

[0077]

[0078] As can be seen from Table 1, for the adsorption resins modified by single metal salt impregnation, their BET specific surface area, micropore volume, and total pore volume are slightly smaller than those of the unmodified adsorption resin, but there is no statistical difference; parameters such as the sphericity after grinding, average pore diameter, and wet apparent density are basically the same as those of the unmodified adsorption resin.

[0079] As Figure 2 can be seen, the adsorption breakthrough time of DCM on the single metal-loaded modified adsorption resins has changed greatly compared with that on the unmodified adsorption resin. The adsorption breakthrough time of DCM on Li(Ⅰ)-AR, Ca(Ⅱ)-AR, Al(Ⅲ)-AR, Fe(Ⅲ)-AR, Mg(Ⅱ)-AR is significantly longer than that on the unmodified adsorption resin, and the adsorption breakthrough time of DCM on Ag(Ⅰ)-AR is significantly shortened. The order of the adsorption breakthrough time of DCM on different metal-loaded modified adsorption resins is: Al(Ⅲ)-AR > Li(Ⅰ)-AR > Mg(Ⅱ)-AR > Ca(Ⅱ)-AR > Fe(Ⅲ)-AR > Ag(Ⅰ)-AR.

[0080] The saturated adsorption capacities of various adsorbents for DCM calculated according to the adsorption permeation curves are shown in Table 2 below. The adsorption capacities of different modified metal ion-modified adsorption resins for DCM are in the following order: Al(Ⅲ)-AR > Li(Ⅰ)-AR > Mg(Ⅱ)-AR > Ca(Ⅱ)-AR > Fe(Ⅲ)-AR > unmodified AR > Ag(Ⅰ)-AR. Among them, the adsorption capacity of Al(Ⅲ)-AR is the largest at 436.83 mg / g, which is 68.81% higher than that of unmodified AR; the adsorption capacity of Ag(Ⅰ)-AR is the smallest at only 230.55 mg / g, and it is lower than the saturated adsorption capacity of unmodified HIAR. The saturated adsorption capacities of Li(Ⅰ)-AR, Mg(Ⅱ)-AR, Ca(Ⅱ)-AR, Fe(Ⅲ)-AR, etc. are in the middle, but they are all higher than that of unmodified AR.

[0081] When different metal ions are loaded on the surface of the hypercrosslinked adsorption resin, the surface acid-base hardness changes. When hard acids such as Al(Ⅲ), Li(Ⅰ), Mg(Ⅱ), Ca(Ⅱ), and Fe(Ⅲ) are loaded on the resin surface, the local hard acidity of the resin surface will be enhanced. Since DCM belongs to a hard base, according to the "hard-hard interaction" principle of the HSAB theory, the resin with hard acid metal ions loaded on the surface has enhanced adsorption capacity for substances belonging to hard bases and DCM, showing a higher adsorption capacity for DCM; Ag(Ⅰ) belongs to a soft acid, and its loading locally enhances the soft acidity of the adsorption resin. According to the "soft-hard combination is unstable" principle of the HSAB theory, the adsorption resin with soft acid metal ions loaded on the surface has a weakened adsorption capacity for the hard base substance DCM. According to Pearson's classification, Al(Ⅲ), Li(Ⅰ), and Mg(Ⅱ) all belong to hard acids with relatively large absolute hardness coefficients, which is consistent with the better adsorption performance shown in the experimental results.

[0082] Table 2 Saturated adsorption capacities of DCM on single metal ion-modified adsorption resins

[0083]

[0084] Example 7

[0085] It can be concluded from Example 6 that the adsorption resins modified with Al(Ⅲ), Li(Ⅰ), and Mg(Ⅱ) have better adsorption performance. Therefore, in order to further investigate the effects of co-doping of the above three metal ions, the effects of bimetallic ion (Li(Ⅰ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Li(Ⅰ)-AR) modification on the adsorption performance of hypercrosslinked adsorption resin (AR) are shown in Table 3 below.

[0086] Table 3 Related parameters such as pore structure of bimetallic ion-modified adsorption resins

[0087]

[0088] As can be seen from Table 3, for the adsorbent resin impregnated and modified with bimetallic salts, its BET specific surface area, micropore volume, and total pore volume are slightly smaller than those of the unmodified adsorbent resin, but there is no statistical difference; parameters such as the roundness rate after grinding, average pore diameter, and wet apparent density are basically equivalent to those of the unmodified adsorbent resin.

[0089] As Figure 3 can be seen, the adsorption breakthrough time of DCM on the bimetallic-loaded modified adsorbent resin has changed significantly compared with that on the unmodified adsorbent resin. The adsorption breakthrough time of DCM on Mg(Ⅱ) / Li(Ⅰ)-AR, Mg(Ⅱ) / Al(Ⅲ)-AR, and Li(Ⅰ) / Al(Ⅲ)-AR is significantly longer than that on the unmodified adsorbent resin. The order of the adsorption breakthrough time of DCM on the bimetallic-loaded modified adsorbent resin is: Li(Ⅰ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Li(Ⅰ)-AR.

[0090] Comparing Figure 2 and Figure 3 , the adsorption breakthrough time of DCM on the bimetallic-loaded modified adsorbent resin is significantly longer than that on the monometallic-loaded modified adsorbent resin. The saturated adsorption capacities of various adsorbents for DCM calculated according to the adsorption breakthrough curves are shown in Table 4 below. The order of the adsorption capacity of the bimetallic-ion modified adsorbent resin for DCM is: Li(Ⅰ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Al(Ⅲ)-AR > Mg(Ⅱ) / Li(Ⅰ) > unmodified AR. Among them, the adsorption capacity of Li(Ⅰ) / Al(Ⅲ)-AR is the largest, which is 567.64 mg / g, an increase of 119.36% compared with the unmodified AR, indicating that Li(Ⅰ) / Al(Ⅲ)-AR and Mg(Ⅱ) / Al(Ⅲ)-AR have better adsorption effects. According to the Pearson classification, the order of the absolute hardness coefficient is Al(Ⅲ) > Li(Ⅰ) > Mg(Ⅱ), which is consistent with the better adsorption performance shown by the results.

[0091] Table 4 Saturated Adsorption Capacities of DCM on Bimetallic-Ion Modified Adsorbent Resins

[0092]

[0093]

[0094] Example 8

[0095] It can be concluded from Example 7 that the adsorption resins modified by Li(Ⅰ) / Al(Ⅲ)-AR and Mg(Ⅱ) / Al(Ⅲ)-AR have better adsorption performance. Therefore, in order to further investigate the enhancement effect of doped multi-walled carbon nanotubes (MWCNTs) on the adsorption performance of the resin, the adsorption performances of AR, MWCNTs-AR, MWCNTs-Mg(Ⅱ) / Li(Ⅰ)-AR, MWCNTs-Mg(Ⅱ) / Al(Ⅲ)-AR and MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR were tested, and the results are shown in Table 5 below.

[0096] Table 5 Relevant parameters such as the pore structure of the adsorption resin modified by multi-walled carbon nanotubes (MWCNTs)

[0097]

[0098] As can be seen from Table 5, for the adsorption resin modified by multi-walled carbon nanotubes (MWCNTs), its BET specific surface area, micropore volume, and total pore volume are slightly smaller than those of the unmodified adsorption resin, but there is no statistical difference; parameters such as the roundness rate after grinding, average pore diameter, and wet apparent density are basically equivalent to those of the unmodified adsorption resin.

[0099] From Figure 4 it can be seen that the adsorption breakthrough time of DCM on the adsorption resin modified by multi-walled carbon nanotubes (MWCNTs) has changed greatly compared with that of the unmodified adsorption resin, and the adsorption breakthrough time of DCM is significantly prolonged compared with the unmodified adsorption resin. Comparing Figure 3 and Figure 4 it can be obtained that the adsorption breakthrough time of DCM on the adsorption resin modified by multi-walled carbon nanotubes (MWCNTs) is significantly prolonged compared with that of the adsorption resin modified by dual-metal loading.

[0100] The saturated adsorption amounts of various adsorbents for DCM calculated according to the adsorption breakthrough curve are shown in Table 6 below. Compared with the unmodified AR, the saturated adsorption amount of MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR has increased by 149.09%, indicating that the adsorption resin enhanced by multi-walled carbon nanotubes (MWCNTs) has better adsorption effect on DCM. The reason is that the characteristics of small size and good flexibility of carbon nanotubes are combined with the porous and macroporous properties of the adsorption resin, and MWCNTs are dispersed into the pores of the adsorption resin by ultrasonic force, so that MWCNTs are blocked in the pores of the adsorption resin and prevent their dissociation. The introduction of carbon nanotubes greatly improves the adsorption capacity of the adsorption resin.

[0101] Table 6 Saturated adsorption amounts of the adsorption resin modified by multi-walled carbon nanotubes (MWCNTs)

[0102]

[0103] Example 9

[0104] According to Examples 6-8, the optimal modified adsorption resin is MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR.

[0105] Taking MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR as an example, the engineering application is as follows:

[0106] Taking a pharmaceutical raw material manufacturing enterprise as the research object, DCM is used as the solvent in the processes of imipenem intermediate condensation reaction, cyclization reaction, extraction, dissolution and concentration, etc. The DCM waste gas is collected separately and treated by the resin adsorption process. The waste gas treatment air volume is 1000m 3 / h, and the DCM emission concentration is about 12000mg / m 3 (calculated as C). After treatment, the emission standard is implemented in the "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021), that is, the non-methane total hydrocarbon NMHC emission concentration is not higher than 60mg / m 3 .

[0107] The original DCM waste gas adsorption and desorption device is transformed by using the adsorption system for dichloromethane in Example 1 of the present invention. The main transformation parts are as follows:

[0108] ① Add a DCM wastewater adsorption and desorption device, specifically add an adsorber. The tank size of the adsorber is Φ1000*2000, and 1m of modified adsorption resin is filled in the adsorber 3 ;

[0109] ② Replace the unmodified resin in the original adsorber with modified resin. The resin volume is the same, and the other parameters are not adjusted.

[0110] The FID detector is used to continuously monitor the inlet and outlet for 24h. The results are as Figure 6 shown. The average concentration of DCM at the inlet is 12748mg / m 3 (calculated as C), and the average concentration of DCM at the outlet is 83mg / m 3 (calculated as C). The average purification efficiency is as high as 99.35%, which is much higher than the purification efficiency of using unmodified adsorption resin. When the dynamic adsorption time reaches 840min, the instantaneous concentration of DCM at the outlet reaches 60mg / m 3(Calculated as C), it shows that the outlet of the device can meet the "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021) within 14 hours of dynamic adsorption, that is, the adsorption and desorption device using modified adsorption resin can meet the requirements of up-to-standard discharge. The original COD of DCM wastewater is about 5000 mg / L. After the DCM wastewater is treated by the modified adsorption resin, the effluent COD drops to 50 mg / L, and the COD index in the wastewater meets the connection standard of the chemical industrial park sewage treatment plant or the water quality standard for sewage discharged into urban sewers, without further treatment. Therefore, the enterprise sets an adsorption cycle at 12 hours, conducts desorption with saturated steam twice a day, consumes a total of 2.5 tons of saturated steam, and the 2.5 tons of DCM wastewater generated is again treated by the modified resin adsorption and desorption to meet the requirements of up-to-standard discharge.

[0111] The operating costs of this device are as follows:

[0112] ① The cost of saturated steam consumption is 2.5 tons / d × 300 yuan / ton = 750 yuan / d;

[0113] ② The electricity cost consumed by the electrical equipment is 6 KW × 24 h / d × 1 yuan / KWh = 144 yuan / d;

[0114] ③ The cost of low-temperature water consumed by the refrigeration system is 400 yuan / d;

[0115] ④ The total of the above operating costs is 1294 yuan / d.

[0116] Compared with the original process, this device saves the costs of wastewater disposal, natural gas, and consumed caustic soda, etc. The operating cost decreases by 68.20% under the condition of meeting up-to-standard discharge. In addition, after the device is continuously used for 7200 h, the loss rate of the modified resin is 3.0%, meeting the technical requirement of Clause 6.3.3.4 of the "Engineering Technical Specification for Treatment of Industrial Organic Waste Gas by Resin Adsorption Method" (T / CPCIF 0175-2021) that "the annual loss rate of resin should be lower than 5%", indicating that the modified resin has good thermal stability.

[0117] Comparative Example 1

[0118] The DCM waste gas is treated by adsorption and desorption using unmodified resin. Except that the original adsorption and desorption system does not have a DCM waste gas adsorption and desorption device, the rest of the design is Figure 7 basically similar, and its design parameters are as follows:

[0119] ① The adsorber adopts a vertical one-adsorption and one-desorption design. The tank body size of the adsorber is Φ1600*2800. Each adsorber is filled with 2 m of unmodified adsorption resin 3 , the cross-sectional flow velocity of the adsorber design is 0.15 m / s, and the gas residence time is 6 s;

[0120] ②Do not set up the DCM wastewater adsorption and desorption system;

[0121] ③The heat exchange area of the primary condenser is 30 m 2 , the wound tube heat exchanger is 10 m 2 , the spiral plate cooler is 3 m 2 , the surface cooler is 50 m 2 .

[0122] The FID detector is used to continuously monitor the inlet and outlet for 24 h. The results are as Figure 5 shown. The average concentration of DCM at the inlet is 13217 mg / m 3 (calculated as C), and the average concentration of DCM at the outlet is 1986 mg / m 3 (calculated as C). The average purification efficiency is only 84.98%. The purification efficiency of this device is not less than 95% for only 5 h. When the dynamic adsorption time reaches 120 min, the instantaneous concentration of DCM at the outlet reaches 60 mg / m 3 (calculated as C), that is, the adsorption time of this device can meet the "Emission Standard of Air Pollutants for Pharmaceutical Industry" (DB32 / 4042-2021) for only 2 h. For the time of desorption regeneration and drying, etc., the shortest adsorption switching time in engineering is generally not less than 4 h, indicating that there are 2 h during the 4 h continuous dynamic adsorption cycle when the device outlet cannot meet the discharge standard requirements. Therefore, the enterprise reconnects the DCM tail gas after the device treatment to the RTO for further treatment. Due to some problems in the RTO treatment of chlorine-containing organic waste gas, the enterprise sets an adsorption cycle at 4 h, conducts 6 times of saturated steam desorption every day, consumes a total of 6 tons of saturated steam, and generates 6 tons of DCM wastewater at the same time. Calculate the operating cost of this device as follows:

[0123] ①The consumption cost of saturated water steam is 6 tons / d × 300 yuan / ton = 1800 yuan / d;

[0124] ②The wastewater disposal cost is 6 tons / d × 200 yuan / ton = 1200 yuan / d;

[0125] ③The natural gas consumption cost for the RTO to further treat the DCM tail gas is 25 m 3 / 10,000 m 3 air·h × 1000 m 3 × 3.5 yuan / m 3 × 24 h / d = 210 yuan / d;

[0126] ④The liquid caustic soda consumed for the oxidation of DCM to generate HCl is 100 yuan / d;

[0127] ⑤The electricity cost consumed by the electrical equipment is 6 KW × 24 h / d × 1 yuan / KWh = 144 yuan / d;

[0128] ⑥The cost of low-temperature water consumed by the refrigeration system is 300 yuan / d;

[0129] ⑦ The total above-mentioned operating cost is 3,754 yuan per day.

[0130] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, 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 special adsorption system for a DCM waste gas adsorption process, the DCM waste gas adsorption process comprising a waste gas adsorption process, a resin desorption process, a desorption gas recovery process and a waste water treatment process, wherein the DCM waste gas is firstly subjected to adsorption purification by the waste gas adsorption system, and the purified gas is discharged by the waste gas adsorption system; when the adsorption capacity of the waste gas adsorption system reaches saturation, a resin desorption process is performed to desorb and remove the DCM adsorbed in the waste gas adsorption system, and restore the waste gas adsorption system to a normal state; the desorbed DCM enters a desorption gas recovery system, and solid-liquid separation is achieved in the system, and the separated solid DCM is recycled; the separated waste water enters a waste water treatment process, and after being treated by the waste water treatment process, the tail water can be directly discharged from the system, and the adsorption, desorption and regeneration process of the DCM waste gas is achieved; the concentration of the DCM waste gas before the treatment is not less than 10000 mg / m 3 ; The concentration of purified gas after treatment is not higher than 60mg / m 3 ; It is characterized in that The invention comprises a waste gas adsorption system, a resin desorption system, a desorption gas recovery system, a resin cooling and drying system, and a wastewater treatment system. The waste gas adsorption system comprises a resin adsorber a (22) and a resin adsorber b (23). The bottoms of the resin adsorber a (22) and the resin adsorber b (23) are provided with an inlet valve a (3) and an inlet valve b (5), respectively; the tops of the resin adsorber a (22) and the adsorber resin adsorber b (23) are provided with an outlet valve a (4) and an outlet valve b (6), respectively; the bottoms of the inner cavities of the resin adsorber a (22) and the resin adsorber b (23) are provided with a high-efficiency gas distributor a (31) and a high-efficiency gas distributor b (32), respectively; the middle of the inner cavities of the resin adsorber a (22) and the resin adsorber b (23) are filled with modified adsorption resin MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR; The preparation method of the modified adsorption resin MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR is as follows: immersing the adsorption resin in a metal ion solution, washing with water to a pH value of 6-7, and drying to obtain a modified adsorption resin loaded with metal ions; MWCNTs are placed in ultrapure water and an MWCNTs dispersion is prepared by ultrasonic dispersion; then a modified adsorption resin loaded with metal ions is immersed in the MWCNTs dispersion and dried again to obtain a modified adsorption resin MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR.

2. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: The resin desorption system comprises a resin adsorber a (22) and a resin adsorber b (23), wherein the tops of the resin adsorber a (22) and the tops of the resin adsorber b (23) are respectively provided with a saturated water vapor inlet valve a (7) and a water vapor inlet valve b (8); the tops of the inner cavities of the resin adsorber a (22) and the tops of the inner cavities of the resin adsorber b (23) are respectively provided with a high-efficiency steam distributor a (28) and a high-efficiency steam distributor b (29); and the bottoms of the resin adsorber a (22) and the bottoms of the resin adsorber b (23) are respectively provided with a desorption gas exhaust valve a (9) and a desorption gas exhaust valve b (12).

3. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: The desorbed gas recovery system comprises a high-efficiency condenser a (19), a high-efficiency condenser b (20), a high-efficiency condenser c (21), a condensate stratification tank (33), a recovery solvent receiving tank (34), and a wastewater receiving tank (35) which are connected in sequence; condensed gas from the high-efficiency condenser a (19), the high-efficiency condenser b (20), the high-efficiency condenser c (21), the condensate stratification tank (33), the recovery solvent receiving tank (34), and the wastewater receiving tank (35) is connected to the inlet of the exhaust gas induced draft fan (17) through a pipeline.

4. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: The resin cooling and drying system comprises a resin adsorber a (22), a resin adsorber b (23) and a water ring vacuum pump (25).

5. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: The wastewater treatment system comprises a resin adsorber c (24); an automatic switching valve a (13) and an automatic switching valve b (14) are arranged at the top of the resin adsorber c (24); an automatic switching valve d (16) and an automatic switching valve c (15) are arranged at the bottom of the resin adsorber c (24); a high-efficiency steam distributor c (30) is arranged at the top of the inner cavity of the resin adsorber c (24), and the middle part is filled with modified adsorption resin MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR.

6. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: In the modified adsorption resin loaded with metal ions, the metal ion loading amount is 5 wt.%.

7. The dedicated adsorption system for the adsorption process of DCM waste gas according to claim 1, characterized in that: In the modified adsorption resin MWCNTs-Li(Ⅰ) / Al(Ⅲ)-AR, the MWCNTs loading amount is 2 wt.%.

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