Energy-saving recovery equipment for waste gas containing high-concentration dichloromethane

Abstract

The utility model provides energy-saving recovery equipment for waste gas containing high-concentration dichloromethane. The energy-saving recovery equipment comprises a low-temperature condensation module and an adsorption recovery module which are sequentially arranged along a gas flow direction, the low-temperature condensation module further comprises a first heat exchanger and a cryogenic heat exchange device; the two ends of the cryogenic heat exchange device are both in pipe connection with the first heat exchanger, and initial waste gas enters the cryogenic heat exchange device through the first heat exchanger and then enters the first heat exchanger again; the adsorption recovery module comprises an adsorption and desorption device, a second heat exchanger, a steam generation device, a solvent recovery storage tank and an exhaust pipe; the adsorption and desorption device is communicated with the first heat exchanger, and the cooled waste gas is subjected to heat exchange through the first heat exchanger, then is introduced into the adsorption and desorption device and is exhausted through an exhaust pipe; the steam generation device, the adsorption and desorption device, the second heat exchanger and the solvent recovery storage tank are communicated in sequence. Heat energy in waste gas is utilized through the first heat exchanger and the second heat exchanger, and energy consumption is reduced.

Description

Technical Field

[0001] This utility model relates to the field of volatile organic solvent recovery technology, specifically to an energy-saving recovery device for waste gas containing high concentrations of dichloromethane. Background Technology

[0002] Currently, the main methods for treating high-concentration organic waste gas and recovering organic solvents include condensation, adsorption, absorption, and membrane separation. High-concentration organic waste gas is suitable for condensation recovery, while low-concentration organic gases are suitable for adsorption recovery.

[0003] The principle of condensation is to utilize the fact that gaseous pollutants have different saturated vapor pressures at different temperatures and pressures. By lowering the temperature, some pollutants are condensed, thereby achieving the purpose of purification or recycling.

[0004] The selection of the condensation temperature for organic waste gas containing high concentrations of dichloromethane is crucial for condensation efficiency. If the condensation temperature is too high, the separation of high-concentration dichloromethane from air may be incomplete, resulting in high inlet concentrations in the downstream adsorption unit, larger unit size, and higher investment and energy consumption. Conversely, if the condensation temperature is too low, it will lead to excessive energy consumption in the condensation unit, resulting in waste. Furthermore, during operation, high-concentration dichloromethane organic waste gas usually contains water vapor, which can cause frost and ice blockage in the condensation unit, preventing it from operating continuously and normally. The selection of condensation temperature and the issues of frost and ice blockage are important problems that condensation technology must address in practical applications.

[0005] After condensation, the gas enters the adsorption unit. Adsorption is a widely used technology in the treatment of volatile organic gases and the recovery of organic solvents. It utilizes the differences in the binding strength between the components in the organic waste gas and the adsorbent to separate the organic components from the air components. Easily adsorbed organic components are fixed in the adsorbent bed, while less easily adsorbed air components are released into the atmosphere. During use, the adsorbent gradually becomes saturated and needs to be regenerated online to restore its adsorption performance and allow the adsorption unit to operate continuously. The regeneration process typically consumes energy, such as steam, and the large amount of steam consumed during regeneration leads to high energy consumption.

[0006] Chinese utility model patent CN217613860U discloses a high-concentration dichloromethane waste gas recovery and treatment system. The system comprises, in sequence along the gas flow direction, a condensation recovery device, an adsorption system, a fan, and an exhaust stack. The condensation recovery device is used to condense and recover high-concentration dichloromethane waste gas. The inlet of the adsorption system is connected to the outlet of the condensation recovery device, and the outlet of the adsorption system is connected to the fan. The fan is also connected to the exhaust stack. The adsorption system is filled with adsorbent material for adsorbing dichloromethane gas. The fan drives the waste gas flowing out of the condensation recovery device into the adsorption system, and the purified gas is discharged from the exhaust stack. While this patent solves the problem of purifying high-concentration dichloromethane waste gas, it does not address the issues of frost and ice blockage in the condensation device when the high-concentration dichloromethane organic waste gas typically contains moisture. Furthermore, it does not solve the problem of continuous online operation of the recovery and treatment system, nor does it disclose a specific implementation device. Utility Model Content

[0007] The purpose of this utility model is to address the shortcomings of existing technologies by providing an energy-saving recovery device for waste gas containing high concentrations of dichloromethane, comprising: a low-temperature condensation module and an adsorption recovery module sequentially along the gas flow direction; the low-temperature condensation module further comprises a first heat exchanger and a cryogenic heat exchange device; both ends of the cryogenic heat exchange device are pipe-connected to the first heat exchanger, the initial waste gas enters the cryogenic heat exchange device after passing through the first heat exchanger and then re-enters the first heat exchanger, the first heat exchanger is used to exchange heat between the initial waste gas and the waste gas cooled by the cryogenic heat exchange device, and the cryogenic heat exchange device is used to cool the initial waste gas after heat exchange by the first heat exchanger;

[0008] The adsorption and recovery module includes an adsorption-desorption device, a second heat exchanger, a steam generating device, a solvent recovery storage tank, and an exhaust pipe. The adsorption-desorption device is connected to the first heat exchanger. The cooled waste gas is passed through the first heat exchanger and then into the adsorption-desorption device, and then discharged through the exhaust pipe. The steam generating device, the adsorption-desorption device, the second heat exchanger, and the solvent recovery storage tank are connected in sequence. The steam generated by the steam generating device enters the adsorption-desorption device, causing the adsorbed organic solvent to be desorbed and form a vapor-liquid mixture with the steam, which enters the second heat exchanger. The second heat exchanger is used to lower the temperature of the vapor-liquid mixture, thereby forming a liquid that is collected in the solvent recovery storage tank.

[0009] Furthermore, the cryogenic heat exchange device includes a first cryogenic waste gas channel device and a second cryogenic waste gas channel device, wherein the first heat exchanger is connected to the first cryogenic waste gas channel device or to the second cryogenic waste gas channel device.

[0010] Furthermore, the first cryogenic exhaust gas passage device includes a first cryogenic heat exchanger, a first refrigerant, and a first heat medium, wherein the first refrigerant and the first heat medium are respectively connected to the first cryogenic heat exchanger;

[0011] The second cryogenic exhaust gas passage device includes a second cryogenic heat exchanger, a second refrigerant, and a second heat medium, which are respectively connected to the second cryogenic heat exchanger.

[0012] Furthermore, the cryogenic heat exchange device also includes a fan, which is circulated in connection with either the first or second cryogenic heat exchanger.

[0013] Furthermore, the cryogenic heat exchange device also includes a third cryogenic waste gas channel device and a fourth cryogenic waste gas channel device. The first heat exchanger is connected in sequence to the first cryogenic waste gas channel device and the third cryogenic waste gas channel device, or in sequence to the first cryogenic waste gas channel device and the fourth cryogenic waste gas channel device, or in sequence to the second cryogenic waste gas channel device and the third cryogenic waste gas channel device, or in sequence to the second cryogenic waste gas channel device and the fourth cryogenic waste gas channel device.

[0014] Furthermore, the third cryogenic exhaust gas passage device includes a third cryogenic heat exchanger, a third refrigerant, and a third heat medium, with the third refrigerant and the third heat medium respectively connected to the third cryogenic heat exchanger.

[0015] The fourth cryogenic exhaust gas passage device includes a fourth cryogenic heat exchanger, a fourth refrigerant, and a fourth heat medium, with the fourth refrigerant and the fourth heat medium respectively connected to the fourth cryogenic heat exchanger.

[0016] Furthermore, the first refrigerant, the first heat medium, the second refrigerant, the second heat medium, the third refrigerant, the third heat medium, the fourth refrigerant, and the fourth heat medium all use the same medium, which includes ethylene glycol aqueous solution, CaCl2 solution, ethanol solution, Glacier refrigerant, and Taupus refrigerant.

[0017] Furthermore, the drying fan, the second heat exchanger, and the adsorption-desorption device are connected in a sequential, end-to-end cycle. The second heat exchanger is used to exchange heat between the drying air generated by the drying fan and the vapor-liquid mixture. The drying air generated by the drying fan removes moisture from the adsorption-desorption device to restore its adsorption capacity.

[0018] Furthermore, the third heat exchanger is connected in a sequential, end-to-end cycle to the drying fan, the second heat exchanger, the third heat exchanger, and the adsorption / desorption device. The third heat exchanger is also connected to the steam generating device. The third heat exchanger is used to further increase the temperature of the drying air generated by the drying fan.

[0019] Furthermore, the adsorption-desorption device includes a first adsorber, a second adsorber, and a third adsorber.

[0020] The beneficial effects of this utility model are as follows:

[0021] 1. When icing occurs, heat medium is introduced into the cryogenic heat exchanger to blow away the melted ice and the water produced by the melting ice, thus solving the problem of difficult and incomplete ice melting in the low-temperature condensing module;

[0022] 2. The first heat exchanger not only raises the temperature of the exhaust gas after it has been cooled by the cryogenic heat exchanger, but also lowers the temperature of the initially high-temperature exhaust gas, significantly reducing the condensation load on the subsequent cryogenic heat exchanger and saving refrigerant consumption.

[0023] 3. The use of steam desorption improves the recovery rate of organic solvents in waste gas;

[0024] 4. By using the preheating of steam through the second heat exchanger, the circulating drying air is heated, so that little or no steam is needed to heat the circulating drying air, thus reducing energy consumption.

[0025] 5. Because each cryogenic heat exchanger can operate independently and alternately, and be maintained in shifts, the waste gas energy-saving recovery system can be operated online continuously, which greatly reduces operating energy consumption and investment costs. Attached Figure Description

[0026] Figure 1 This is a structural block diagram of an energy-saving recovery system for waste gas containing high concentrations of organic solvents.

[0027] Figure 2 This is a structural block diagram of the low-temperature condensation module.

[0028] Figure 3 This is a structural block diagram of another type of low-temperature condensation module.

[0029] Figure 4 This is a structural block diagram of the adsorption and recovery module.

[0030] Figure reference numerals: 100-Low-temperature condensation module; 200-Adsorption and recovery module; 110-First heat exchanger; 120-Cryogenic heat exchange device; 121-First cryogenic waste gas passage device; 1211-First cryogenic heat exchanger; 1212-First refrigerant; 1213-First heat medium; 122-Second cryogenic waste gas passage device; 1221-Second cryogenic heat exchanger; 1222-Second refrigerant; 1223-Second heat medium; 123-Fan; 124-Third cryogenic waste gas passage device; 1241-... Three cryogenic heat exchangers; 1242 - Third refrigerant; 1243 - Third heat medium; 125 - Fourth cryogenic exhaust gas passage device; 1251 - Fourth cryogenic heat exchanger; 1252 - Fourth refrigerant; 1253 - Fourth heat medium; 210 - Adsorption-desorption device; 211 - First adsorber; 212 - Second adsorber; 213 - Third adsorber; 220 - Drying fan; 230 - Second heat exchanger; 240 - Steam generating device; 250 - Solvent recovery storage tank; 260 - Exhaust pipe; 270 - Third heat exchanger

[0031] 1301 - Inlet valve of the first cryogenic heat exchanger; 1302 - Outlet valve of the first cryogenic heat exchanger; 1311 - Inlet valve of the second cryogenic heat exchanger; 1312 - Outlet valve of the second cryogenic heat exchanger; 1321 - Inlet valve of the third cryogenic heat exchanger; 1322 - Outlet valve of the third cryogenic heat exchanger; 1331 - Inlet valve of the fourth cryogenic heat exchanger; 1332 - Outlet valve of the fourth cryogenic heat exchanger; 1341 - First refrigerant inlet valve; 1342 - First heat medium inlet valve; 1343 - First refrigerant outlet valve Valve; 1344 - First heat medium outlet valve; 1351 - Second refrigerant inlet valve; 1352 - Second heat medium inlet valve; 1353 - Second refrigerant outlet valve; 1354 - Second heat medium outlet valve; 1361 - Third refrigerant inlet valve; 1362 - Third heat medium inlet valve; 1363 - Third refrigerant outlet valve; 1364 - Third heat medium outlet valve; 1371 - Fourth refrigerant inlet valve; 1372 - Fourth heat medium inlet valve; 1373 - Fourth refrigerant outlet valve; 1374 - Fourth Heat medium outlet valve; 1381-Gas purge first inlet valve; 1382-Gas purge first outlet valve; 1383-Gas purge second inlet valve; 1384-Gas purge second outlet valve; 2801-First exhaust gas inlet valve; 2802-Second exhaust gas inlet valve; 2803-Third exhaust gas inlet valve; 2804-First exhaust gas outlet valve; 2805-Second exhaust gas outlet valve; 2806-Third exhaust gas outlet valve; 2811-First steam desorption inlet valve; 2812-... 2813 - Steam desorption inlet valve; 2814 - Steam desorption outlet valve; 2815 - Steam desorption outlet valve; 2816 - Steam desorption outlet valve; 2821 - Circulating dry air inlet valve; 2822 - Circulating dry air inlet valve; 2823 - Circulating dry air inlet valve; 2824 - Circulating dry air outlet valve; 2825 - Circulating dry air outlet valve; 2826 - Circulating dry air outlet valve. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0033] Example 1

[0034] like Figure 1 As shown, an energy-saving recovery device for waste gas containing high concentration of dichloromethane includes a low-temperature condensation module 100 and an adsorption recovery module 200 in sequence along the gas flow direction, with the outlet of the low-temperature condensation module 100 connected to the inlet of the adsorption recovery module 200.

[0035] refer to Figure 2The low-temperature condensation module 100 further includes a first heat exchanger 110 and a cryogenic heat exchange device 120. Both ends of the cryogenic heat exchange device 120 are pipe-connected to the first heat exchanger 110. Exhaust gas enters the cryogenic heat exchange device 120 after passing through the first heat exchanger 110, and then re-enters the first heat exchanger 110. The first heat exchanger 110 is used to exchange heat with the exhaust gas after it has been cooled by the cryogenic heat exchange device 120. The cryogenic heat exchange device 120 is used to cool the initial exhaust gas after the heat exchange with the first heat exchanger 110, causing some water vapor and organic solvents in the exhaust gas to condense and be discharged. Since the initial exhaust gas temperature before entering the cryogenic condensation module 100 is relatively high, and the cryogenic heat exchanger 120 can cool the high-temperature exhaust gas to between -30°C and -40°C, if it is directly discharged into the subsequent adsorption and recovery device, not only will a large amount of cold energy be wasted, but it may even cause the adsorption material of the subsequent adsorption and recovery device to freeze, resulting in system overpressure. Therefore, in this invention, the cooled exhaust gas is passed back into the first heat exchanger 110 to exchange heat with the initial high-temperature exhaust gas that first entered the first heat exchanger 110. On the one hand, this temperature range can effectively condense and recover high-concentration (>30000PPM) dichloromethane. On the other hand, it can not only raise the temperature of the cooled exhaust gas, but also lower the temperature of the initial high-temperature exhaust gas, greatly reducing the cooling pressure of the subsequent cryogenic heat exchanger 120 and saving refrigerant consumption. After heat exchange, the temperature of the exhaust gas, cooled by the cryogenic heat exchanger 120, drops to between 0°C and 10°C, with a relative humidity between 1% and 5%. The initial high-temperature exhaust gas temperature is between 0°C and 8°C, with a relative humidity between 95% and 100%. The heat exchange can remove up to 42% to 62% of the moisture from high-concentration organic waste gas, making it suitable for the condensation process of dichloromethane waste gas containing a large amount of water. This invention reduces operating energy consumption while ensuring safety by fully utilizing the cold energy of the cooled exhaust gas.

[0036] In this embodiment, specifically, the cryogenic heat exchange device 120 includes a first cryogenic waste gas passage device 121 and a second cryogenic waste gas passage device 122, and the first heat exchanger 110 is connected to either the first cryogenic waste gas passage device 121 or the second cryogenic waste gas passage device 122. The first cryogenic waste gas passage device 121 includes a first cryogenic heat exchanger 1211, a first refrigerant 1212, and a first heat medium 1213, with the first refrigerant 1212 and the first heat medium 1213 respectively connected to the first cryogenic heat exchanger 1211. The second cryogenic waste gas passage device 122 includes a second cryogenic heat exchanger 1221, a second refrigerant 1222, and a second heat medium 1223, with the second refrigerant 1222 and the second heat medium 1223 respectively connected to the second cryogenic heat exchanger 1221. This embodiment includes two cryogenic heat exchangers. During equipment operation, one cryogenic heat exchanger cools the exhaust gas, while the other performs maintenance. Because frost forms on the surface of the heat exchange pipes during exhaust gas cooling, affecting continuous equipment operation, the two cryogenic heat exchangers alternate cooling operations to ensure continuous operation. During maintenance, a heat transfer medium is introduced to raise the temperature of the cryogenic heat exchanger, melting the frost. The heat transfer medium heats the condenser to 20°C–40°C for ice melting. The refrigerant and the heat transfer medium used for ice melting can be the same medium, including ethylene glycol aqueous solution, CaCl2 solution, ethanol solution, Glacier refrigerant, and Taupus refrigerant.

[0037] The cryogenic heat exchange device 120 includes a fan 123, which is circulated in connection with either the first cryogenic heat exchanger 1211 or the second cryogenic heat exchanger 1221. The fan 123 is used to purge frost and water generated during the melting of frost from the first and second cryogenic heat exchangers 1211 and 1221, allowing the water to flow out from a valve. If the water from the melting frost is not completely purged, it will refreeze during cooling. The fan 123 also accelerates airflow during pre-cooling, speeding up the cooling of exhaust gas and saving refrigerant and electrical energy. The melting time is generally greater than 5 minutes, with an optimal range of 15–60 minutes. If the melting time is too short, incomplete melting will occur, affecting the normal operation of the cryogenic condensation system. After the first cryogenic heat exchanger 1211 and the second cryogenic heat exchanger 1221 have finished melting, they need to be pre-cooled to ensure they reach the set condensation temperature before the exhaust gas is introduced into them for further cooling. This ensures the stability of the gas condensation temperature and prevents fluctuations in the inlet concentration of the exhaust gas entering the downstream adsorption and recovery module due to temperature fluctuations.

[0038] refer to Figure 4The adsorption and recovery module 200 also includes a purified waste gas discharge pipeline, an organic solvent recovery pipeline, and a circulating drying pipeline.

[0039] The purified exhaust gas discharge pipeline includes an adsorption-desorption device 210 and an exhaust pipe 260 connected to the adsorption-desorption device 210. The adsorption-desorption device 210 is connected to the first heat exchanger 110. After the cooled exhaust gas is heated by the first heat exchanger 110, it is directly introduced into the adsorption-desorption device 210. After the adsorption-desorption device 210 adsorbs the organic solvents remaining in the cooled exhaust gas, the organic solvents in the exhaust gas meet the emission standards and are discharged through the exhaust pipe 260. In this embodiment, the adsorption material is one or a combination of activated carbon, activated carbon fiber, and resin.

[0040] The organic solvent recovery pipeline includes a steam generating device 240, an adsorption-desorption device 210, a second heat exchanger 230, and a solvent recovery storage tank 250 connected in sequence. When the steam generated by the steam generating device 240 enters the adsorption-desorption device 210, the adsorbed organic solvent is desorbed and forms a vapor-liquid mixture with the steam, which then enters the second heat exchanger 230. In the second heat exchanger 230, heat is exchanged with the drying air driven by the drying fan 220, raising the temperature of the drying air. Meanwhile, the temperature of the vapor-liquid mixture decreases, forming a liquid that is collected in the solvent recovery storage tank 250.

[0041] The circulating drying pipeline includes a drying fan 220, a second heat exchanger 230, and an adsorption-desorption device 210 connected in sequence. This embodiment includes three adsorbers to enhance the adsorption effect: a first adsorber 211, a second adsorber 212, and a third adsorber 213. The second heat exchanger 230 exchanges heat between the drying air driven by the drying fan 220 and the mixture of water vapor and organic vapor generated by the steam generator 240. The drying air driven by the drying fan 220 removes moisture from the adsorption-desorption device 210 to restore its adsorption capacity. Preferably, the circulating drying pipeline also includes a third heat exchanger 270. The drying fan 220, the second heat exchanger 230, the third heat exchanger 270, and the adsorption-desorption device 210 are connected in sequence. The third heat exchanger 270 is also connected to the steam generator 240 to further increase the temperature of the drying air. Generally, drying air needs a certain temperature to ensure the drying function is realized. The heating process of drying air consumes energy. However, the waste heat of steam is utilized through the second heat exchanger 230, which saves energy. The third heat exchanger 270 is used when the heat exchange of the second heat exchanger 230 is insufficient to raise the drying air to the specified temperature.

[0042] The above functions are achieved by opening each valve, as detailed below:

[0043] exist Figure 2Simultaneously, the inlet valve 1301 and outlet valve 1302 of the first cryogenic heat exchanger are opened to activate the first cryogenic waste gas passage device 121. Simultaneously, the inlet valve 1311 and outlet valve 1312 of the second cryogenic heat exchanger are opened to activate the second cryogenic waste gas passage device 122. Simultaneously, the first gas purging inlet valve 1381 and outlet valve 1382 are opened to allow the fan 123 to purge water or frost from the first cryogenic heat exchanger 1211 and its associated pipes. Simultaneously, the second gas purging inlet valve 1383 and outlet valve 1384 are opened to allow the fan 123 to purge water or frost from the second cryogenic heat exchanger 1221 and its associated pipes. Figure 4 In the exhaust gas discharge pipeline, simultaneously opening the first exhaust gas inlet valve 2801 and the first exhaust gas outlet valve 2804 activates the adsorption function of the first adsorber 211. Simultaneously opening the second exhaust gas inlet valve 2802 and the second exhaust gas outlet valve 2805 activates the adsorption function of the second adsorber 212. Simultaneously opening the third exhaust gas inlet valve 2803 and the third exhaust gas outlet valve 2806 activates the adsorption function of the third adsorber 213. In the organic solvent recovery pipeline, simultaneously opening the first vapor desorption inlet valve 2811 and the first vapor desorption outlet valve 2814 initiates organic solvent desorption for the first adsorber 211. Simultaneously opening the second vapor desorption inlet valve 2812 and the second vapor desorption outlet valve 2815 initiates organic solvent desorption for the second adsorber 212. Simultaneously opening the third steam desorption inlet valve 2813 and the third steam desorption outlet valve 2816 initiates organic solvent desorption for the third adsorber 213. In the circulating drying pipeline, simultaneously opening the first circulating drying air inlet valve 2821 and the first circulating drying air outlet valve 2824 allows the drying air driven by the drying fan 220 to dry the water adsorbed by the first adsorber 211. Simultaneously opening the second circulating drying air inlet valve 2822 and the second circulating drying air outlet valve 2825 allows the drying air driven by the drying fan 220 to dry the water adsorbed by the second adsorber 212. Simultaneously opening the third circulating drying air inlet valve 2823 and the third circulating drying air outlet valve 2826 allows the drying air driven by the drying fan 220 to dry the water adsorbed by the third adsorber 213.

[0044] refer to Figure 2 and Figure 4 Since the functions of the other valves are relatively easy to understand, they will not be explained one by one here.

[0045] Example 2

[0046] like Figure 3 As shown, compared with Example 1, the low-temperature condensation module 100 has the following differences:

[0047] The cryogenic heat exchange device 120 further includes a third cryogenic waste gas passage device 124 and a fourth cryogenic waste gas passage device 125. The first heat exchanger 110 is connected in sequence to the first cryogenic waste gas passage device 121 and the third cryogenic waste gas passage device 124; or in sequence to the first cryogenic waste gas passage device 121 and the fourth cryogenic waste gas passage device 125. The first heat exchanger 110 is connected in sequence to the second cryogenic waste gas passage device 122 and the third cryogenic waste gas passage device 124, or in sequence to the second cryogenic waste gas passage device 122 and the fourth cryogenic waste gas passage device 125.

[0048] The cryogenic heat exchange device 120 includes a fan 123, which is sequentially connected to the first cryogenic waste gas passage device 121 and the third cryogenic waste gas passage device 124, or sequentially connected to the first cryogenic waste gas passage device 121 and the fourth cryogenic waste gas passage device 125. The fan 123 is also sequentially connected to the second cryogenic waste gas passage device 122 and the third cryogenic waste gas passage device 124, or sequentially connected to the second cryogenic waste gas passage device 122 and the fourth cryogenic waste gas passage device 125.

[0049] The connection of the above pipelines is achieved by opening each valve, as referenced Figure 3 The function of each valve is relatively easy to understand, so it will not be explained one by one here.

[0050] The third cryogenic waste gas passage device 124 and the fourth cryogenic waste gas passage device 125 both include refrigerant and heat transfer medium, and have the same function and structure as the first cryogenic waste gas passage device 121 or the second cryogenic waste gas passage device 122. The first cryogenic waste gas passage device 121 or the second cryogenic waste gas passage device 122 serves as a primary cryogenic heat exchange device, while the third cryogenic waste gas passage device 124 and the fourth cryogenic waste gas passage device 125 serve as secondary cryogenic heat exchange devices. By adding secondary cryogenic heat exchange devices, high-concentration organic waste gas can be condensed according to the temperature gradient, avoiding excessive load on the primary cryogenic heat exchanger. If the load is too high, the required parameter configuration will be too high, resulting in a low COP value (coefficient of performance) and lack of energy saving.

[0051] The other structures are the same as in Example 1.

[0052] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An energy-saving recovery device for waste gas containing high concentrations of dichloromethane, characterized in that, include: Along the gas flow direction, it includes a low-temperature condensation module (100) and an adsorption and recovery module (200). The low-temperature condensation module (100) further includes a first heat exchanger (110) and a cryogenic heat exchange device (120); both ends of the cryogenic heat exchange device (120) are connected to the first heat exchanger (110) in pipe. The initial waste gas enters the cryogenic heat exchange device (120) after passing through the first heat exchanger (110) and then re-enters the first heat exchanger (110). The first heat exchanger (110) is used to exchange heat between the initial waste gas and the waste gas cooled by the cryogenic heat exchange device (120). The cryogenic heat exchange device (120) is used to cool the initial waste gas after the heat exchange with the first heat exchanger (110). The adsorption and recovery module (200) includes an adsorption-desorption device (210), a second heat exchanger (230), a steam generating device (240), a solvent recovery storage tank (250), and an exhaust pipe (260). The adsorption-desorption device (210) is connected to the first heat exchanger (110). The cooled exhaust gas is passed through the first heat exchanger (110) for heat exchange and then enters the adsorption-desorption device (210) and is discharged through the exhaust pipe (260). The steam generating device (240), the adsorption-desorption device (210), the second heat exchanger (230), and the solvent recovery storage tank (250) are connected in sequence. The steam generated by the steam generating device (240) enters the adsorption-desorption device (210), causing the adsorbed organic solvent to be desorbed and form a vapor-liquid mixture with the steam, which enters the second heat exchanger (230). The second heat exchanger (230) is used to lower the temperature of the vapor-liquid mixture and form a liquid that is collected in the solvent recovery storage tank (250).

2. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 1, characterized in that: The cryogenic heat exchange device (120) includes a first cryogenic waste gas passage device (121) and a second cryogenic waste gas passage device (122). The first heat exchanger (110) is connected to the first cryogenic waste gas passage device (121) or to the second cryogenic waste gas passage device (122).

3. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 2, characterized in that: The first cryogenic exhaust gas passage device (121) includes a first cryogenic heat exchanger (1211), a first refrigerant (1212) and a first heat medium (1213), wherein the first refrigerant (1212) and the first heat medium (1213) are respectively connected to the first cryogenic heat exchanger (1211); The second cryogenic exhaust gas passage device (122) includes a second cryogenic heat exchanger (1221), a second refrigerant (1222) and a second heat medium (1223), with the second refrigerant (1222) and the second heat medium (1223) respectively connected to the second cryogenic heat exchanger (1221).

4. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 3, characterized in that: The cryogenic heat exchange device (120) also includes a fan (123), which is circulatedly connected to the first cryogenic heat exchanger (1211) or the second cryogenic heat exchanger (1221).

5. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 3, characterized in that: The cryogenic heat exchange device (120) further includes a third cryogenic waste gas passage device (124) and a fourth cryogenic waste gas passage device (125). The first heat exchanger (110) is connected in sequence to the first cryogenic waste gas passage device (121) and the third cryogenic waste gas passage device (124), or in sequence to the first cryogenic waste gas passage device (121) and the fourth cryogenic waste gas passage device (125), or in sequence to the second cryogenic waste gas passage device (122) and the third cryogenic waste gas passage device (124), or in sequence to the second cryogenic waste gas passage device (122) and the fourth cryogenic waste gas passage device (125).

6. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 5, characterized in that: The third cryogenic exhaust gas passage device (124) includes a third cryogenic heat exchanger (1241), a third refrigerant (1242) and a third heat medium (1243), wherein the third refrigerant (1242) and the third heat medium (1243) are respectively connected to the third cryogenic heat exchanger (1241); The fourth cryogenic exhaust gas passage device (125) includes a fourth cryogenic heat exchanger (1251), a fourth refrigerant (1252) and a fourth heat medium (1253), with the fourth refrigerant (1252) and the fourth heat medium (1253) respectively connected to the fourth cryogenic heat exchanger (1251).

7. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 6, characterized in that: The first refrigerant (1212), the first heat medium (1213), the second refrigerant (1222), the second heat medium (1223), the third refrigerant (1242), the third heat medium (1243), the fourth refrigerant (1252), and the fourth heat medium (1253) all use the same medium, which includes ethylene glycol aqueous solution, CaCl2 solution, ethanol solution, Glacier refrigerant, and Taupus refrigerant.

8. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 1, characterized in that, Also includes: A drying fan (220), a second heat exchanger (230), and an adsorption-desorption device (210) are connected in a sequential, end-to-end circulation. The second heat exchanger (230) is used to exchange heat between the drying air generated by the drying fan (220) and the vapor-liquid mixture. The drying air generated by the drying fan (220) removes moisture from the adsorption-desorption device (210) to restore the adsorption capacity of the adsorption-desorption device (210).

9. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 8, characterized in that, Also includes: The third heat exchanger (270) is connected in a sequential loop with the drying fan (220), the second heat exchanger (230), the third heat exchanger (270) and the adsorption / desorption device (210). The third heat exchanger (270) is also connected with the steam generating device (240). The third heat exchanger (270) is used to further increase the temperature of the drying air generated by the drying fan (220).

10. The energy-saving recovery equipment for high-concentration dichloromethane waste gas according to claim 1, characterized in that: The adsorption-desorption device (210) includes a first adsorber (211), a second adsorber (212) and a third adsorber (213).

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