VOC (volatile organic compound) mixed gas recovery and waste heat utilization system

Abstract

The utility model discloses a VOC (volatile organic compound) mixed gas recovery and waste heat utilization system which comprises four groups of circularly controlled adsorption towers and a desorption circulating system for desorbing the adsorption towers, the desorption circulating system is used for performing multi-stage cooling and shunting on circulating gas flowing out of the adsorption towers in a desorption state to form liquid flow and gaseous flow, and the liquid flow and the gaseous flow are communicated with the adsorption towers. After being collected, the liquid flow serves as a cooling medium and is pumped to the adsorption tower in an adsorption state for cooling circulation; and the gaseous flow is heated by waste heat utilization and then enters the desorption state adsorption tower. According to the VOC mixed gas recovery and waste heat utilization system disclosed by the utility model, the desorbed gas is subjected to multi-stage cooling, so that a solvent material contained in the gas can be completely condensed, and the desorbed gas is subjected to mutual heat exchange by utilizing the cooled gas before desorption, so that waste heat can be better utilized; and meanwhile, the cooled and separated flux material is fed into the adsorption tower in an adsorption state as a cooling medium to be used as a cold source, so that the cold source is effectively utilized.

Description

Technical Field

[0001] The utility model relates to the field of tail gas treatment systems, in particular to a VOC mixed gas waste heat recovery and utilization system. Background Art

[0002] EAC, MEK and IPA are solvents, colorless, transparent liquids with a pungent odor, and widely used fine chemical products. They have excellent solubility and quick drying properties, and are very important chemical raw materials and adhesive industrial solvents, especially widely used in the coating industry and adhesives.

[0003] In the production process of aluminum-plastic composite film for medical packaging, most of the solvents required for the adhesive used are EAC or MEK as diluent solvents. During the drying process, under the action of high-temperature air, the solvents in the adhesive solution are taken away by the hot air flow, forming a VOC gas mixed with hot air, EAC, MEK and IPA.

[0004] At present, domestic pharmaceutical packaging manufacturers deal with the VOC mixed gas generated by pharmaceutical aluminum-plastic composites in the following ways: First, direct incineration using natural gas, but incineration not only consumes excess natural gas and increases production costs, but also pollutes the environment and does not meet the exhaust gas treatment standards.

[0005] Second, the VOC mixed gas is recovered. The specific process is to first condense and recover it through a condenser, then pass it through a desorption tower for adsorption, and then cool and recover it. It has the following shortcomings: Secondly, during the recovery process, EAC or MEK, IPA, etc. in the mixed gas are only recovered through one adsorption, which is easy to fail to meet the emission standards, thus polluting the environment; and the adsorption and desorption of the adsorption tower are intermittent operations. Once the adsorption tower is saturated with adsorption, it needs to be stopped, and then the adsorption tower needs to be desorbed and regenerated before it can be operated again, resulting in low efficiency and inability to continuously treat the exhaust gas.

[0006] The applicant's prior application, application number: CN202223490224.4, discloses a VOC mixed gas recovery device for aluminum-plastic composite film for pharmaceutical packaging, in which a dedicated desorption tower is provided for desorbing each absorption tower, and the desorption tower is used to desorb the activated carbon in the absorption tower to achieve a "transfer" effect, and the above-mentioned various solvents in the process waste gas absorbed in the desorption tower will eventually be transferred to the solvent recovery tank. With such a design, during use, not only a first heater is required to be set up for desorbing each absorption tower, but also a second heater is required to desorb the desorption tower, which leads to repeated processes, and the separately arranged heat exchangers and condensers are all independently cooled, and the effect is relatively poor, and there is no further heat utilization for the cooling solvent material condensed in the solvent recovery tank.

[0007] In view of the above, it is necessary to propose a VOC mixed gas waste heat recovery and utilization system to solve the above problems. Utility Model Content

[0008] The purpose of the utility model is to solve the above technical problems and provide a VOC mixed gas waste heat recovery and utilization system.

[0009] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a VOC mixed gas recovery and waste heat utilization system, including four groups of circulation-controlled adsorption towers, and also including a desorption circulation system for desorbing the adsorption towers. The desorption circulation system performs multi-stage cooling and diversion on the circulating gas flowing out of the adsorption tower in the desorption state to form a liquid flow and a gaseous flow. After the liquid flow is collected, it is pumped to the adsorption tower in the adsorption state as a cooling medium for cooling circulation; the gaseous flow enters the desorption state adsorption tower after being heated by waste heat utilization.

[0010] Furthermore, the desorption circulation system includes a first self-heat exchanger, a first cooler, a second cooler, a second self-heat exchanger, and a cryogenic refrigerator; the desorption circulation gas flowing out of the adsorption tower passes through the first self-heat exchanger, the first cooler, the second cooler, the second self-heat exchanger, and the cryogenic refrigerator in sequence; the condensate of the first cooler and the second cooler is collected in a first collecting tank; the condensate of the second self-heat exchanger and the cryogenic refrigerator is collected in a second collecting tank.

[0011] Furthermore, the gas outlet at the top of the second collecting tank is connected to the cold end of the second self-heat exchanger, enters the cold end of the first self-heat exchanger after the first-stage preheating in the second self-heat exchanger, and is subjected to the second-stage preheating by the first self-heat exchanger, and enters the desorption adsorption tower as the clean pre-desorption gas.

[0012] Furthermore, the pre-desorption gas is pressurized by a circulating fan and then passed through a heater to reach a predetermined gas temperature before being sent to a desorption adsorption tower.

[0013] Furthermore, the desorbed gas flowing out from the top of the desorbed adsorption tower enters the hot end of the first self-heat exchanger, and the desorbed gas enters the shell side of the primary cooler and the secondary cooler in sequence. The shell side of the primary cooler and the secondary cooler are both provided with a gas outlet and a liquid outlet. The gas outlet of the primary cooler is connected to the shell side inlet of the secondary cooler, and the liquid outlets of the primary cooler and the secondary cooler are both connected to the first collecting tank.

[0014] Furthermore, the gas outlet of the secondary cooler is connected to the shell side of the second self-heat exchanger, the shell side of the second self-heat exchanger is provided with a third gas outlet and a third liquid outlet, the third gas outlet is connected to the cryogenic refrigerator, the outlet end of the cryogenic refrigerator is connected to the second collecting tank, the third liquid outlet of the second self-heat exchanger is connected to the second collecting tank, the top of the second collecting tank is provided with a third gas outlet, and the third gas outlet is connected to the tube side of the second self-heat exchanger.

[0015] Furthermore, the liquids in the first collection tank and the second collection tank are concentrated and converged into a third collection tank, and the bottom of the third collection tank is connected to the cooling coil in the adsorption tower through a cooling cycle outlet pipe.

[0016] Compared with the prior art, the beneficial effects of the utility model are as follows: the utility model is a VOC mixed gas recovery and waste heat utilization system that performs multi-stage cooling on the desorbed gas, thereby completely condensing the solvent contained in the gas, and utilizing the pre-desorbed gas formed by the cooling to perform heat exchange with the post-desorbed gas, thereby making better use of the waste heat; at the same time, the cooled and separated flux material is sent into the adsorption tower in the adsorption state as a cooling medium and used as a cold source, thereby effectively utilizing the cold source. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a VOC mixed gas waste heat recovery and utilization system of the utility model. Figure 1 ;

[0018] Figure 2 This is a schematic diagram of the structure of a VOC mixed gas waste heat recovery and utilization system of the utility model. Figure 2 ;

[0019] In the figure: 1. adsorption tower; 2. liquid flow; 3. gaseous flow; 4. first self-heat exchanger; 5. primary cooler; 6. secondary cooler; 7. second self-heat exchanger; 8. cryogenic freezer; 9. first collecting tank; 10. second collecting tank; 11. primary preheating; 12. secondary preheating; 13. gas before desorption; 14. circulating fan; 15. heater; 16. gas after desorption; 17. first gas outlet; 18. first liquid outlet; 19. second gas outlet; 20. second liquid outlet; 21. third gas outlet; 22. third liquid outlet; 23. third collecting tank; 24. cooling circulation water supply pipe; 25. cooling circulation return pipe; 26. cooling coil. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0021] A VOC mixed gas waste heat recovery and utilization system, such as Figure 1 , 2 As shown, it includes four groups of adsorption towers 1 with circulation control. During actual control, the four groups of adsorption towers 1 are respectively circulated in the following four states: adsorption state, heating state, regeneration state, and cooling state. That is, during production, there is always an adsorption tower 1 in the adsorption state, and each group of adsorption towers 1 is circulated for regeneration, so as to facilitate entering the adsorption state again.

[0022] The desorption circulation system for desorbing the adsorption tower 1 is also included. Specifically, the desorption circulation system performs multi-stage cooling and diversion on the circulating gas flowing out of the adsorption tower 1 in the desorption state to form a liquid flow 2 and a gaseous flow 3, such as Figure 2 As shown, after desorption, the gas 16 passes through the circulation system and is separated into gaseous and liquid states.

[0023] After the liquid stream 2 is collected, it is pumped as a cooling medium to the adsorption tower 1 in the adsorption state for cooling circulation; the gaseous stream 3 is heated by waste heat and enters the desorption state adsorption tower 1. In this way, the coldness in the liquid condensate is applied to the adsorption tower 1 in the adsorption state as a cooling medium; and the gaseous medium can be sent to the adsorption tower 1 in the desorption state to desorb the adsorption tower 1 because the solvent material is separated to form a clean pre-desorption gas 13, and the gaseous medium is a gas with a lower temperature. The coldness of the gas can be used to preheat the desorption gas with a higher temperature, and the heat can be reasonably reused by using cold and heat exchange to achieve the effect of energy saving and emission reduction.

[0024] Specifically, Figure 1 As shown, the desorption circulation system includes a first self-heat exchanger 4, a first-stage cooler 5, a second-stage cooler 6, a second self-heat exchanger 7, and a cryogenic refrigerator 8; the desorption circulation gas (i.e., the desorbed gas 16) flowing out of the adsorption tower 1 passes through the first self-heat exchanger 4, the first-stage cooler 5, the second-stage cooler 6, the second self-heat exchanger 7, and the cryogenic refrigerator 8 in sequence; the condensate of the first-stage cooler 5 and the second-stage cooler 6 is collected in a first collecting tank 9; the condensate of the second self-heat exchanger 7 and the cryogenic refrigerator 8 is collected in a second collecting tank 10.

[0025] Specifically, the gas outlet at the top of the second collecting tank 10 is connected to the cold end of the second self-heat exchanger 7, and enters the cold end of the first self-heat exchanger 4 after the first-stage preheating 11 of the second self-heat exchanger 7, and is subjected to the second-stage preheating 12 by the first self-heat exchanger 4, and enters the desorption adsorption tower 1 as the clean pre-desorption gas 13. After the solvent in the post-desorption gas 16 is condensed and separated, the gas becomes clean to form the pre-desorption gas 13, and the clean pre-desorption gas 13 is used to enter the desorption adsorption tower 1, and the activated carbon in the adsorption tower 1 is regenerated for subsequent use.

[0026] Furthermore, the pre-desorption gas 13 is pressurized by the circulating fan 14 and passes through the heater 15 to reach a predetermined gas temperature before being sent to the desorption adsorption tower 1. The circulating fan 14 serves as a power source for the gas flow of the desorption circulation system. In actual use, a compressor can also be used according to actual conditions. The gas entering the heater 15 is used to control the gas 13 before desorption to reach a predetermined temperature. The heater 15 can be an electric heater 15, and its power can be controlled to control the gas temperature. Furthermore, before entering the heater 15, the gas passes through the second self-heat exchanger 7, the first self-heat exchanger 4 primary preheating 11 and the secondary preheating 12, so that the gas can be preheated and the coldness of the gas can be effectively utilized.

[0027] The desorbed gas 16 flowing out of the top of the desorbed adsorption tower 1 enters the hot end of the first self-heat exchanger 4, such as Figure 1 As shown, the desorbed gas 16 enters the shell side of the first self-heat exchanger 4, and the desorbed gas 16 enters the shell side of the primary cooler 5 and the secondary cooler 6 in sequence. The shell sides of the primary cooler 5 and the secondary cooler 6 are both provided with a gas outlet and a liquid outlet. Specifically, the primary cooler 5 is recorded as the first gas outlet 17 and the first liquid outlet 18, and the secondary cooler 6 is recorded as the second gas outlet 19 and the second liquid outlet 20. The gas outlet of the primary cooler 5 is connected to the shell side inlet of the secondary cooler 6, and the liquid outlets of the primary cooler 5 and the secondary cooler 6 are both connected to the first collection tank 9. The cooled flux material is separated from the gas after twice cooling, and collected in the first collection tank 9, waiting for the coldness of the liquid to be utilized.

[0028] Further, the gas outlet of the secondary cooler 6 is connected to the shell side of the second self-heat exchanger 7, and the shell side of the second self-heat exchanger 7 is provided with a third gas outlet 21 and a third liquid outlet 22, and the third gas outlet 21 is connected to the cryogenic refrigerator 8, and the outlet end of the cryogenic refrigerator 8 is connected to the second collecting tank 10, and the third liquid outlet 22 of the second self-heat exchanger 7 is connected to the second collecting tank 10, and the top of the second collecting tank 10 is provided with a third gas outlet 21, and the third gas outlet 21 is connected to the tube side of the second self-heat exchanger 7. The cryogenic refrigerator 8 can adopt a Freon heat exchanger, and the gas can be cryogenically cooled by Freon, so that the solvent in the gas is completely cooled and separated, so that the gas is cleaner, and it is convenient to desorb the adsorption tower 1.

[0029] The liquids in the first collecting tank 9 and the second collecting tank 10 are concentrated and converged into the third collecting tank 23. The bottom of the third collecting tank 23 is connected to the cooling coil 26 in the adsorption tower 1 through a cooling circulation outlet pipe. As the liquid flow 2 is cooled and condensed, the cold capacity inside the liquid flow 2 can be utilized. The existing adsorption tower 1 is originally provided with a hot and cold water coil, and the hot water or cold water flowing into the coil is controlled according to the state of adsorption or desorption. In this embodiment, a cooling coil 26 is added to the adsorption tower 1, and the condensate collected in the third collecting tank 23 is sent to the cooling coil 26 for circulation cooling. Figure 1 As shown, the cooling circulation return water pipe 25 flows back into the third collection tank 23. In actual use, a fourth collection tank can be set up separately, and the cooling circulation return water pipe 25 is sent into the fourth collection tank, so as to avoid mixing of cold and hot flows.

[0030] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A VOC mixed gas waste heat recovery and utilization system, comprising four sets of cycle-controlled adsorption towers (1), characterized in that: It also comprises a desorption circulation system for desorbing the adsorption tower (1), wherein the desorption circulation system performs multi-stage cooling and diversion on the circulating gas flowing out of the adsorption tower (1) in the desorption state to form a liquid flow (2) and a gaseous flow (3); the liquid flow (2) is collected and pumped to the adsorption tower (1) in the adsorption state as a cooling medium for cooling circulation; and the gaseous flow (3) enters the desorption state adsorption tower (1) after being heated by utilizing waste heat.

2. A VOC mixed gas waste heat recovery and utilization system according to claim 1, characterized in that: The desorption circulation system comprises a first self-heat exchanger (4), a first cooler (5), a second cooler (6), a second self-heat exchanger (7), and a cryogenic refrigerator (8); the desorption circulation gas flowing out of the adsorption tower (1) passes through the first self-heat exchanger (4), the first cooler (5), the second cooler (6), the second self-heat exchanger (7), and the cryogenic refrigerator (8) in sequence; the condensate of the first cooler (5) and the second cooler (6) is collected in a first collection tank (9); the condensate of the second self-heat exchanger (7) and the cryogenic refrigerator (8) is collected in a second collection tank (10).

3. A VOC mixed gas waste heat recovery and utilization system according to claim 2, characterized in that: The gas outlet at the top of the second collecting tank (10) is connected to the cold end of the second self-heat exchanger (7), enters the cold end of the first self-heat exchanger (4) after primary preheating (11) in the second self-heat exchanger (7), and is secondary preheated (12) by the first self-heat exchanger (4), and enters the desorption adsorption tower (1) as clean pre-desorption gas (13).

4. A VOC mixed gas waste heat recovery and utilization system according to claim 3, characterized in that: The pre-desorption gas (13) is pressurized by a circulating fan (14) and then passed through a heater (15) to reach a predetermined gas temperature before being sent to the desorption adsorption tower (1).

5. A VOC mixed gas waste heat recovery and utilization system according to claim 2, characterized in that: The desorbed gas (16) flowing out from the top of the desorbed adsorption tower (1) enters the hot end of the first self-heat exchanger (4), and the desorbed gas (16) enters the shell side of the primary cooler (5) and the secondary cooler (6) in sequence. The shell side of the primary cooler (5) and the secondary cooler (6) are both provided with a gas outlet and a liquid outlet. The gas outlet of the primary cooler (5) is connected to the shell side inlet of the secondary cooler (6), and the liquid outlets of the primary cooler (5) and the secondary cooler (6) are both connected to the first collecting tank (9).

6. A VOC mixed gas waste heat recovery and utilization system according to claim 5, characterized in that: The gas outlet of the secondary cooler (6) is connected to the shell side of the second self-heat exchanger (7); the shell side of the second self-heat exchanger (7) is provided with a third gas outlet (21) and a third liquid outlet (22); the third gas outlet (21) is connected to the cryogenic refrigerator (8); the outlet end of the cryogenic refrigerator (8) is connected to the second collecting tank (10); the third liquid outlet (22) of the second self-heat exchanger (7) is connected to the second collecting tank (10); the top of the second collecting tank (10) is provided with a third gas outlet (21); the third gas outlet (21) is connected to the tube side of the second self-heat exchanger (7).

7. A VOC mixed gas waste heat recovery and utilization system according to claim 6, characterized in that: The liquids in the first collection tank (9) and the second collection tank (10) are concentrated and converged into the third collection tank (23), and the bottom of the third collection tank (23) is connected to the cooling coil (26) in the adsorption tower (1) through a cooling circulation water supply pipe (24).

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