Condensation refrigeration system of VOCs treatment device

Abstract

The utility model relates to the technical field of coal chemical equipment, in particular to a condensation refrigeration system of a VOCs (volatile organic compounds) treatment device, which comprises a first heat exchanger tube pass input end connected with a first liquid phase propylene conveying branch tube, a tube pass output end connected with a first output branch tube, a shell pass input end connected with a refrigerant conveying tube, and a second heat exchanger tube pass output end connected with a second liquid phase propylene conveying branch tube. The shell pass output end is connected with a first refrigerant output pipe; the tube pass input end of the second heat exchanger is connected with a second liquid-phase propylene conveying branch pipe, the tube pass output end of the second heat exchanger is connected with a second output branch pipe, the shell pass input end of the second heat exchanger is connected with a first conveying pipe for flowing VOCs and methanol gas, and the shell pass output end of the second heat exchanger is connected with a second conveying pipe; the tube pass input end of the third heat exchanger is connected with the first refrigerant output pipe, the tube pass output end is connected with the second refrigerant output pipe, the shell pass input end is connected with the second conveying pipe, and the shell pass output end is connected with the third conveying pipe. According to the utility model, the problems of poor pre-cooling effect, long driving time and high power consumption of the compressor are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of coal chemical equipment, in particular to a condensation refrigeration system of a VOCs treatment device. Background Art

[0002] VOCs refer to organic compounds with a saturated vapor pressure greater than 70.91Pa at room temperature, a boiling point below 50-260℃ at a standard atmospheric pressure of 101.3kPa, and an initial distillation point equal to 250℃, or any volatile organic solid or liquid at room temperature and pressure. VOCs can be further divided into alkanes, aromatic hydrocarbons, esters, aldehydes, and others according to their chemical structure. More than 300 types have been identified so far, the most common of which are benzene, toluene, xylene, styrene, trichloroethylene, trichloromethane, trichloroethane, diisocyanate (TDI), diisocyanatotoluene, etc. VOCs will pollute the atmosphere if they are directly discharged into the air, and will cause harm to human health if inhaled or contacted by humans, so they need to be treated by VOCs treatment devices.

[0003] At present, the domestic petrochemical industry mainly uses adsorption, absorption, membrane separation and condensation methods for oil and gas recovery. Among them, the adsorption method has large losses and high operating costs; the absorption method equipment occupies a large space, has high operating costs, and it is difficult for tail gas emissions to meet the standards; the membrane separation method has a large equipment load and high investment, so the condensation method is often used to perform deep cold condensation recovery of VOCs to make the tail gas meet the emission standards.

[0004] In the coal chemical industry, refrigeration processes are widely involved in various chemical processes. To achieve lower refrigeration temperatures and higher refrigeration effects, higher energy consumption is required according to the principle of energy conservation. The cooling capacity of the cold field at the second heat exchanger of the original process requires the addition of multiple compressors to work on the refrigerant in order to achieve the cooling capacity required by the process. However, the skid-mounted equipment with multiple compressors occupies a large area and has a poor pre-cooling effect when started. In order to achieve the pre-cooling effect, the start-up time must be increased, which will inevitably consume electricity during operation. Utility Model Content

[0005] The purpose of the utility model is to overcome the problems of poor pre-cooling effect, long start-up time and high power consumption in the prior art, and to provide a condensing refrigeration system for a VOCs treatment device.

[0006] The utility model provides a condensing refrigeration system of a VOCs treatment device, comprising:

[0007] A first heat exchanger, wherein the tube side input end is connected to a first liquid phase propylene delivery branch pipe with a first valve, the tube side output end is connected to a first output branch pipe, the shell side input end is connected to a refrigerant delivery pipe, and the shell side output end is connected to a first refrigerant output pipe, so as to cool the refrigerant output from the first refrigerant output pipe after heat exchange with liquid phase propylene;

[0008] The second heat exchanger has a tube side input end connected to a second liquid phase propylene delivery branch pipe with a second valve, a tube side output end connected to a second output branch pipe, a shell side input end connected to a first delivery pipe, the first delivery pipe is used to deliver methanol gas containing VOCs, and a shell side output end connected to the second delivery pipe, so that the methanol gas containing VOCs delivered to the shell side of the second heat exchanger is heat-exchanged with the liquid phase propylene delivered to the tube side of the second heat exchanger, so that part of the methanol is liquefied;

[0009] The third heat exchanger has a tube-side input end connected to the first refrigerant output pipe, a tube-side output end connected to the second refrigerant output pipe, a shell-side input end connected to the second delivery pipe, the second delivery pipe is used to deliver methanol gas containing VOCs, and a shell-side output end connected to the third delivery pipe for allowing the methanol gas containing VOCs fed into the shell side of the third heat exchanger to exchange heat again with the refrigerant fed into the tube side of the third heat exchanger, so as to liquefy the methanol gas that has not been liquefied in the second heat exchanger.

[0010] Preferably, a fourth heat exchanger is also included, the third delivery pipe is connected to the shell side input end of the fourth heat exchanger, the tube side input end of the fourth heat exchanger 18 is connected to the fourth delivery pipe, the shell side output end of the fourth heat exchanger is connected to the first delivery pipe, and the shell side output end of the fourth heat exchanger is connected to the fifth delivery pipe.

[0011] Preferably, the bottom of the second heat exchanger is connected to a first output pipe, the bottom of the third heat exchanger is connected to a second output pipe, and the bottom of the fourth heat exchanger is connected to a third output pipe.

[0012] Preferably, the first output pipe, the second output pipe and the third output pipe are all connected to the methanol collection tank.

[0013] Preferably, the fourth delivery pipe is connected to the gas-liquid separation tank through a fan, and is used to deliver the methanol gas containing VOCs separated by the gas-liquid separation tank into the fourth delivery pipe through the fan; the fifth delivery pipe is connected to the activated carbon adsorption unit.

[0014] Preferably, the first output branch pipe and the second output branch pipe are connected to the propylene output main pipe through a first tee, and the first liquid-phase propylene delivery branch pipe and the second liquid-phase propylene delivery branch pipe are connected to the propylene delivery main pipe through a second tee.

[0015] Preferably, the propylene output main pipe is connected to the output end of the propylene compressor, and the propylene delivery main pipe is connected to the input end of the propylene compressor.

[0016] Preferably, the first liquid-phase propylene delivery branch pipe, the second liquid-phase propylene delivery branch pipe, the refrigerant delivery pipe, the first refrigerant output pipe, the second output branch pipe, the first delivery pipe, the second delivery pipe, the first output pipe, the propylene output main pipe and the second refrigerant output pipe are all made of low-temperature steel or stainless steel.

[0017] Preferably, the propylene delivery main pipe and the propylene output main pipe are both provided with stop valves.

[0018] Preferably, a third valve is provided on the propylene output main pipe, and the first valve, the second valve and the third valve are all pneumatic valves.

[0019] Compared with the prior art, the beneficial effects of the utility model are:

[0020] 1. The utility model introduces liquid propylene, which reduces the precooling time of the condensing system on the one hand, and saves electricity on the other hand. According to a screw compressor with a rated power of 140KW and an annual operation of 7200 hours, it can save about 550,000 yuan per year. It reduces the start-up time and achieves the purpose of energy saving and consumption reduction, while reducing the power consumption caused by adding secondary compressor refrigeration and the safety risks during the operation of the compressor.

[0021] 2. The utility model provides cooling capacity to the compressed gaseous refrigerant by exchanging heat between the refrigerant and propylene in the third heat exchanger. The cooled refrigerant provides more cooling capacity through throttling expansion, and finally cools the VOCs gas to -75°C. The VOCs gas cooled to -75°C is then sent to the fourth heat exchanger to participate in the heat exchange of the VOCs gas in the fourth heat exchanger, and the excess gaseous methanol in the gaseous state of the VOCs gas can be condensed. The heat-exchanged VOCs gas is cooled to about -30°C, which is beneficial to cooling capacity recovery, improves the pre-cooling effect, and saves electric energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an actual production process flow chart of the prior art.

[0023] Figure 2 This is the actual production process flow chart of the utility model

[0024] Description of reference numerals:

[0025] 1. Propylene transport main pipe, 2. Second liquid-phase propylene transport branch pipe, 3. First liquid-phase propylene transport branch pipe, 4. First heat exchanger, 5. Second heat exchanger, 6. First output branch pipe, 7. Refrigerant transport pipe, 8. First refrigerant output pipe, 9. Second output branch pipe, 10. First transport pipe, 11. Second transport pipe, 12. First output pipe 13. Propylene output main pipe, 14. Third heat exchanger, 15. Third transport pipe, 16. Second refrigerant output pipe, 17. Second output pipe, 18. Fourth heat exchanger, 19. Fourth transport pipe, 20. Fifth transport pipe, 21. Third output pipe, 22. Compressor. DETAILED DESCRIPTION

[0026] The following is combined with Figure 2 , the specific implementation of the utility model is described in detail, but it should be understood that the protection scope of the utility model is not limited by the specific implementation. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0027] like Figure 2 As shown, the utility model provides a condensing refrigeration system of a VOCs treatment device, comprising: a first heat exchanger 4, a second heat exchanger 5 and a third heat exchanger 14, wherein the tube side input end of the first heat exchanger 4 is connected to a first liquid phase propylene delivery branch pipe 3 with a first valve, the tube side output end of the first heat exchanger 4 is connected to a first output branch pipe 6, the shell side input end of the first heat exchanger 4 is connected to a refrigerant delivery pipe 7, and the shell side output end of the first heat exchanger 4 is connected to a first refrigerant output pipe 8 for cooling the refrigerant output from the first refrigerant output pipe 8 after heat exchange with liquid phase propylene; the tube side input end of the second heat exchanger 5 is connected to a second liquid phase propylene delivery branch pipe 2 with a second valve, the tube side output end of the second heat exchanger 5 is connected to a second output branch pipe 9, and the shell side input end of the second heat exchanger 5 is connected to a first delivery pipe 10, and the first delivery pipe 10 is used to deliver the refrigerant containing VOCs The shell side output end of the second heat exchanger 5 is connected to the second delivery pipe 11, so that the methanol gas containing VOCs fed into the shell side of the second heat exchanger 5 is heat-exchanged once with the liquid propylene fed into the tube side of the second heat exchanger 5 to liquefy part of the methanol; the tube side input end of the third heat exchanger 14 is connected to the first refrigerant output pipe 8, the tube side output end of the third heat exchanger 14 is connected to the second refrigerant output pipe 16, the shell side input end of the third heat exchanger 14 is connected to the second delivery pipe 11, the second delivery pipe 11 is used to transport the methanol gas containing VOCs, the shell side output end of the third heat exchanger 14 is connected to the third delivery pipe 15, which is used to allow the methanol gas containing VOCs fed into the shell side of the third heat exchanger 14 to exchange heat again with the refrigerant fed into the tube side of the third heat exchanger 14, so that the methanol gas that has not been liquefied in the second heat exchanger 5 is liquefied.

[0028] Specifically, it also includes a fourth heat exchanger 18, the third delivery pipe 15 is connected to the shell side input end of the fourth heat exchanger 18, the tube side input end of the fourth heat exchanger 18 is connected to the fourth delivery pipe 19, the shell side output end of the fourth heat exchanger 18 is connected to the first delivery pipe 10, and the shell side output end of the fourth heat exchanger 18 is connected to the fifth delivery pipe 20.

[0029] Specifically, the bottom of the second heat exchanger 5 is connected to the first output pipe 12 , the bottom of the third heat exchanger 14 is connected to the second output pipe 17 , and the bottom of the fourth heat exchanger 18 is connected to the third output pipe 21 .

[0030] Specifically, the first output pipe 12 , the second output pipe 17 , and the third output pipe 21 are all connected to the methanol collecting tank.

[0031] Specifically, the fourth delivery pipe 19 is connected to the gas-liquid separation tank through a fan, and is used to deliver the methanol gas containing VOCs separated by the gas-liquid separation tank into the fourth delivery pipe 19 through the fan; the fifth delivery pipe 20 is connected to the inlet buffer tank of the activated carbon adsorption unit; the -30°C VOCS gas after condensation heat exchange is delivered to the activated carbon adsorption unit through the fifth delivery pipe (20) and the inlet buffer tank of the activated carbon adsorption unit.

[0032] Specifically, the first output branch pipe 6 and the second output branch pipe 9 are connected to the propylene output main pipe 13 through a first tee, and the first liquid-phase propylene delivery branch pipe 3 and the second liquid-phase propylene delivery branch pipe 2 are connected to the propylene delivery main pipe 1 through a second tee.

[0033] Specifically, the propylene output main pipe 13 is connected to the output end of the propylene compressor, and the propylene delivery main pipe 1 is connected to the input end of the propylene compressor.

[0034] Specifically, the first liquid-phase propylene delivery branch pipe 3, the second liquid-phase propylene delivery branch pipe 2, the refrigerant delivery pipe 7, the first refrigerant output pipe 8, the second output branch pipe 9, the first delivery pipe 10, the second delivery pipe 11, the first output pipe 12, the propylene output main pipe 13 and the second refrigerant output pipe 16 are all made of low-temperature steel or stainless steel.

[0035] Specifically, both the propylene delivery main pipe 1 and the propylene output main pipe 13 are provided with stop valves. The purpose of providing the stop valves is to effectively isolate the propylene increasing device from the VOCs treatment device by closing the valves when the device is shut down.

[0036] Specifically, a third valve is provided on the propylene output main pipe 13, and the first valve, the second valve and the third valve are all pneumatic valves. The pneumatic valve is an instrument air valve, which provides a power source and is used to open and close the valve. Liquid propylene flows in the first liquid-phase propylene delivery branch pipe 3 and the second liquid-phase propylene delivery branch pipe 2. The pneumatic valve (opening and closing valve) is set to open and close to control the flow of liquid propylene, and can quickly and effectively cut the flow when an abnormal situation occurs to prevent the occurrence of an incident.

[0037] Working principle:

[0038] Due to the coldness of the cold field at the second heat exchanger of the original process, multiple compressors need to be added to work on the refrigerant to achieve the cooling capacity required by the process. However, the skid-mounted equipment using multiple compressors will lead to large floor space and poor pre-cooling effect during startup. In order to achieve the pre-cooling effect, the startup time must be increased, which will inevitably consume electricity during operation. Figure 1 As shown, the process path of the condensation refrigeration system of the VOCs treatment device given in the prior art is described as follows:

[0039] The rich methanol from the tank body is sent to the gas-liquid separation tank for gas-liquid separation and buffering. The separated VOCs+methanol gas is sucked into the fourth delivery pipe 19 connected thereto by the fan, and the fourth delivery pipe 19 is connected to the tube side input end of the fourth heat exchanger 18, so the VOCs+methanol gas sent into the tube side of the fourth heat exchanger 18 through the fourth delivery pipe 19 is heat exchanged with the VOCs+methanol gas containing a small amount of cooled gas sent into the shell side of the fourth heat exchanger 18 through the third delivery pipe 15. The cooled VOCs+methanol gas after heat exchange is sent into the shell side of the second heat exchanger 5 through the first delivery pipe 10 connected to the tube side outlet of the fourth heat exchanger 18. The VOCs gas heated after heat exchange is sent to the shell side of the second heat exchanger 5 through the The fifth delivery pipe 20 is sent to the activated carbon adsorption system for treatment; the VOCs+methanol gas sent to the second heat exchanger 5 is compressed and cooled by the compressor connected to the shell side of the second heat exchanger 5, and then sent to the second heat exchanger 5 again, and then sent to the third heat exchanger 14 through the second delivery pipe 11 for heat exchange, and then sent to the shell side of the fourth heat exchanger 18 by the third delivery pipe 15 connected to the shell side output end of the third heat exchanger 14. The methanol cooled by heat exchange flows out from the bottom of the second heat exchanger 5, the third heat exchanger 14 and the fourth heat exchanger 18. Since the VOCs gas sent out through the fifth delivery pipe 20 needs to be cooled to -30°C before it can be absorbed by the activated carbon, it is necessary to increase the start-up time of the compressor, which will cause power consumption during the operation of the compressor.

[0040] In order to solve this problem, the utility model provides a technical improvement plan, and the process path is described as follows:

[0041] First, 0.4MPa liquid propylene is sent into the propylene delivery main pipe 1 through the input end of the propylene compressor, and then the liquid propylene flowing in the propylene delivery main pipe 1 is sent into the first heat exchanger 4 connected to the first liquid propylene delivery branch pipe 3 and the second heat exchanger 5 connected to the second liquid propylene delivery branch pipe 2 through the second tee, wherein the liquid propylene flowing in the inner tube side of the first heat exchanger 4 and the refrigerant sent into the shell side of the first heat exchanger 4 through the refrigerant delivery pipe 7 are heat exchanged, and after the heat exchange, the liquid propylene becomes gaseous propylene and is output from the first output branch pipe 6. , and the refrigerant cooled after heat exchange is sent to the tube side of the third heat exchanger 14 through the first refrigerant output pipe 8 to participate in the heat exchange of the third heat exchanger 14; the liquid phase propylene sent to the tube side of the second heat exchanger 5 through the second liquid phase propylene delivery branch pipe 2 after diversion is exchanged with the VOCs+methanol gas sent to the shell side of the second heat exchanger 5 through the first delivery pipe 10 for liquid-gas heat exchange, and the propylene converted into gas phase after heat exchange is output through the second output branch pipe 9, and the VOCs+methanol gas cooled after heat exchange is sent to the third heat exchanger 14 through the second delivery pipe 11 and sent to the third heat exchanger The refrigerant in the tube side 14 is subjected to gas-liquid heat exchange, and the refrigerant after heat exchange is outputted from the second refrigerant output pipe 16. At this time, the VOCs gas is cooled to -75°C, and the VOCs + methanol gas containing a small amount of methanol that is further cooled after heat exchange is again sent to the shell side of the fourth heat exchanger 18 through the third delivery pipe 15, and the VOCs + methanol gas in the tube side of the fourth heat exchanger 18 is continuously sent to the fourth delivery pipe 19 for heat exchange, and then the VOCs gas cooled to -75°C in the third delivery pipe 15 is sent to the fourth heat exchanger to participate in the fourth heat exchange The VOCs gas in the device is heat exchanged, and the gas transported by the fourth delivery pipe 19 is sent from the rich methanol in the tank body to the VOCs + methanol gas after gas-liquid separation in the gas-liquid separation tank. The VOCs + methanol gas is sucked into the fourth delivery pipe 19 connected thereto by a fan, which can condense the excess gaseous methanol in the gaseous state of the VOCs gas, and the VOCs after heat exchange are sent out through the fifth delivery pipe 20. The heat-exchanged VOCs gas is cooled to about -30°C, which is beneficial to cold recovery, improves the pre-cooling effect, and saves electric energy.

[0042] The VOCs after heat exchange are sent out through the fifth delivery pipe 20 and adsorbed in the inlet buffer tank of the activated carbon adsorption unit, while the VOCs + methanol cooled after heat exchange are sent to the shell of the second heat exchanger 5 through the first delivery pipe 10 to participate in heat exchange. The methanol cooled by heat exchange flows out from the bottom of the second heat exchanger 5, the third heat exchanger 14 and the fourth heat exchanger 18 and is collected in the methanol collection tank. In this process, no compressor is needed, which solves the problem that the skid-mounted equipment of the compressor will cause a large floor space. At the same time, liquid propylene is used for heat exchange in this heat exchange process, which not only reduces the precooling time of the condensing system, but also saves electricity. According to a screw compressor with a rated power of 140KW and an annual operation of 7200 hours, the cost can be saved by about 550,000 yuan per year. The start-up time is reduced and the purpose of energy saving and consumption reduction is achieved, while the power consumption caused by adding secondary compressor refrigeration and the safety risks during the operation of the compressor are reduced.

[0043] like Figure 2 As shown, a thermometer is provided on the first output branch pipe 6 connected to the tube outlet of the first heat exchanger 4; a thermometer is also provided on the second delivery pipe 11 connected to the tube outlet of the second heat exchanger 5. The purpose of providing these two thermometers is to detect the tube outlet temperature of the first heat exchanger 4 and the tube outlet temperature of the second heat exchanger 5, so as to control the opening of the first valve and the second valve respectively according to the temperature, thereby controlling the propylene flow into the first heat exchanger 4 and the second heat exchanger 5. Thus, the problem of Figure 1 The cooling capacity of the cold field at the second heat exchanger 5 of the original process requires the addition of multiple compressors to work on the refrigerant in order to achieve the cooling capacity required by the process.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A condensing refrigeration system for a VOCs treatment device, characterized in that: include: A first heat exchanger (4), wherein the tube side input end is connected to a first liquid phase propylene delivery branch pipe (3) with a first valve, the tube side output end is connected to a first output branch pipe (6), the shell side input end is connected to a refrigerant delivery pipe (7), and the shell side output end is connected to a first refrigerant output pipe (8), so as to cool the refrigerant output from the first refrigerant output pipe (8) after heat exchange with liquid phase propylene; The second heat exchanger (5) has a tube side input end connected to a second liquid phase propylene delivery branch pipe (2) with a second valve, a tube side output end connected to a second output branch pipe (9), a shell side input end connected to a first delivery pipe (10), the first delivery pipe (10) is used to deliver methanol gas containing VOCs, and a shell side output end connected to a second delivery pipe (11), so that the methanol gas containing VOCs delivered to the shell side of the second heat exchanger (5) and the liquid phase propylene delivered to the tube side of the second heat exchanger (5) are subjected to a heat exchange once, so that part of the methanol is liquefied; The third heat exchanger (14) has a tube-side input end connected to the first refrigerant output pipe (8), a tube-side output end connected to the second refrigerant output pipe (16), a shell-side input end connected to the second delivery pipe (11), the second delivery pipe (11) being used to deliver methanol gas containing VOCs, and a shell-side output end connected to the third delivery pipe (15) for once again exchanging heat between the methanol gas containing VOCs delivered to the shell side of the third heat exchanger (14) and the refrigerant delivered to the tube side of the third heat exchanger (14), so as to liquefy the methanol gas that has not been liquefied in the second heat exchanger (5).

2. A condensing refrigeration system for a VOCs treatment device as claimed in claim 1, characterized in that: The heat exchanger (18) further comprises a fourth heat exchanger (18), wherein the third delivery pipe (15) is connected to the shell-side input end of the fourth heat exchanger (18), the tube-side input end of the fourth heat exchanger (18) is connected to the fourth delivery pipe (19), the shell-side output end of the fourth heat exchanger (18) is connected to the first delivery pipe (10), and the shell-side output end of the fourth heat exchanger (18) is connected to the fifth delivery pipe (20).

3. A condensing refrigeration system for a VOCs treatment device as claimed in claim 2, characterized in that: The bottom of the second heat exchanger (5) is connected to a first output pipe (12), the bottom of the third heat exchanger (14) is connected to a second output pipe (17), and the bottom of the fourth heat exchanger (18) is connected to a third output pipe (21).

4. A condensing refrigeration system for a VOCs treatment device as claimed in claim 3, characterized in that: The first output pipe (12), the second output pipe (17) and the third output pipe (21) are all connected to the methanol collection tank.

5. A condensing refrigeration system for a VOCs treatment device as claimed in claim 4, characterized in that: The fourth delivery pipe (19) is connected to the gas-liquid separation tank via a fan, and is used to deliver the methanol gas containing VOCs separated by the gas-liquid separation tank into the fourth delivery pipe (19) via the fan; the fifth delivery pipe (20) is connected to the activated carbon adsorption unit.

6. A condensing refrigeration system for a VOCs treatment device as claimed in claim 5, characterized in that: The first output branch pipe (6) and the second output branch pipe (9) are connected to the propylene output main pipe (13) through a first tee, and the first liquid phase propylene delivery branch pipe (3) and the second liquid phase propylene delivery branch pipe (2) are connected to the propylene delivery main pipe (1) through a second tee.

7. A condensing refrigeration system for a VOCs treatment device as claimed in claim 6, characterized in that: The propylene output main pipe (13) is connected to the output end of the propylene compressor, and the propylene delivery main pipe (1) is connected to the input end of the propylene compressor.

8. A condensing refrigeration system for a VOCs treatment device as claimed in claim 7, characterized in that: The first liquid-phase propylene delivery branch pipe (3), the second liquid-phase propylene delivery branch pipe (2), the refrigerant delivery pipe (7), the first refrigerant output pipe (8), the second output branch pipe (9), the first delivery pipe (10), the second delivery pipe (11), the first output pipe (12), the propylene output main pipe (13) and the second refrigerant output pipe (16) are all made of low-temperature steel or stainless steel.

9. A condensing refrigeration system for a VOCs treatment device as claimed in claim 8, characterized in that: The propylene delivery main pipe (1) and the propylene output main pipe (13) are both provided with stop valves.

10. The condensing refrigeration system of a VOCs treatment device according to claim 1, characterized in that: The propylene output main pipe (13) is provided with a third valve, and the first valve, the second valve and the third valve are all pneumatic valves.

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