Industrial tail gas waste heat recovery system

Abstract

The invention relates to an industrial tail gas waste heat recovery system, which comprises a heat pump unit and a heating medium water unit, the heat pump unit comprises a compressor (1), a condenser (2), a throttle valve (3) and an evaporator (4), the heating medium water unit comprises a circulating water pump (9) and a gas-water heat exchanger (10), fresh air (11) enters industrial equipment (13) through the gas-water heat exchanger (10), and the industrial equipment (13) enters the condenser (2). Tail gas exhausted from industrial equipment (13) forms low-temperature tail gas (5) and liquid water (6) through an evaporator (4) to be exhausted, a working medium of a heat pump unit heats water sent by a circulating water pump (9) through a compressor (1) and a condenser (2), then enters the evaporator (4) through a throttling valve (3) and then returns to the compressor (1), and the water sent out from the circulating water pump (9) is heated through the condenser (2) and then enters a gas-water heat exchanger (10) to heat fresh air (11). And the low-temperature water from the gas-water heat exchanger (10) returns to the circulating water pump (9).

Description

Technical Field

[0001] This invention belongs to the field of industrial exhaust gas waste heat recovery technology, and specifically relates to an industrial exhaust gas waste heat recovery system that uses heat pump and heat medium water circulation technology. Background Technology

[0002] In industrial production, a large amount of waste heat carried by industrial exhaust gas is not fully utilized, resulting in energy waste and thermal pollution problems.

[0003] Chinese patents 201921221641.4 - A Variable Load Dehumidification Heat Pump Drying System, 201922345609.3 - A Washing and Drying Heat Recovery and Heating System, 202210890210.7 - A Dynamic Combined Energy-Saving Dehumidification System, and 2025110388242 - An Industrial Flue Gas Waste Heat Closed-Loop Cascade Recovery System and Method, etc., have proposed isenthalpic closed-loop industrial exhaust gas waste heat recovery and dehumidification technology. Practical applications, such as in spray fluidized bed drying systems, have achieved good energy-saving and economic benefits. However, the ductwork arrangement is complex and results in significant heat loss, making construction difficult and the system layout subject to many environmental limitations.

[0004] Therefore, how to reasonably recover waste heat from industrial exhaust gas and overcome the problems existing in the above-mentioned technology applications is worthy of in-depth research. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology mentioned above. It adopts heat pump and closed-loop water circulation technology to dehumidify industrial exhaust gas while realizing the recovery of isenthalpic waste heat from industrial exhaust gas. The system has a simple and compact layout and low heat loss.

[0006] The objective of this invention is achieved through the following measures:

[0007] An industrial exhaust gas waste heat recovery system includes a heat pump unit, a heat transfer medium water unit, and connecting pipelines. The heat pump unit includes a compressor 1, a condenser 2, a throttling valve 3, and an evaporator 4. The heat transfer medium water unit includes a circulating water pump 9 and a gas-water heat exchanger 10.

[0008] Fresh air 11 is heated by air-water heat exchanger 10 and then enters industrial equipment 13 for use by industrial equipment 13. The exhaust gas discharged from industrial equipment 13 is dehumidified and cooled by evaporator 4 to form low-temperature exhaust gas 5 and liquid water 6, which are then discharged.

[0009] The working fluid in the heat pump unit is pressurized and heated by the compressor 1, then heated by the condenser 2 to heat the water delivered by the circulating water pump 9. After cooling, the working fluid enters the evaporator 4 through the expansion valve 3, where it absorbs the heat from the exhaust gas discharged from the industrial equipment 13, and then enters the compressor 1 again, thus forming the working fluid circulation process of the heat pump unit.

[0010] Water pumped from the circulating water pump 9 is heated by the condenser 2 and then enters the air-water heat exchanger 10 to heat the fresh air 11. The low-temperature water from the air-water heat exchanger 10 returns to the circulating water pump 9, thus forming the water circulation process of the heat transfer medium water unit.

[0011] A steam trap 7 is provided: the exhaust gas discharged from the industrial equipment 13 is cooled by the evaporator 4, and the resulting condensate is discharged through the steam trap 7.

[0012] A buffer tank 8 is provided: water delivered from the circulating water pump 9 is heated by the condenser 2 and then enters the air-water heat exchanger 10 to heat the fresh air 11. The low-temperature water from the air-water heat exchanger 10 returns to the circulating water pump 9 through the buffer tank 8, thus forming a water circulation process of the heat transfer medium water unit; or water delivered from the circulating water pump 9 is heated by the buffer tank 8 and the condenser 2 and then enters the air-water heat exchanger 10 to heat the fresh air 11. The low-temperature water from the air-water heat exchanger 10 returns to the circulating water pump 9, thus forming a water circulation process of the heat transfer medium water unit.

[0013] The heat transfer water unit operates under positive pressure. The gas space of the buffer tank 8 is pressurized with nitrogen cylinders or compressed air, and its pressure is higher than the saturated steam pressure corresponding to the outlet water temperature of the condenser 2. The circulating water pump 9 is used to provide the water circulation power for the heat transfer water unit.

[0014] A heat exchanger 15 is provided: water pumped from the circulating water pump 9 is heated by the condenser 2, then enters the air-water heat exchanger 10 through the heat exchanger 15 to heat the fresh air 11. The low-temperature water exiting the air-water heat exchanger 10 returns to the circulating water pump 9, thus forming a water circulation process in the heat transfer medium water unit. The heat exchanger 15 is used to heat the cold fluid 16 into a hot fluid 17 or to provide external heating.

[0015] The industrial equipment 13 includes a drying tower, washing and drying equipment, coating and drying lines such as lithium battery cathode coating and drying lines, natural gas boilers, oil boilers, etc. The fresh air 11 is heated and used as a drying or combustion medium for the industrial equipment 13.

[0016] A purification device 14 is provided: the exhaust gas from the industrial equipment 13 enters the evaporator 4 through the purification device 14. The purification device 14 is used to remove solid particles, sulfides or nitrogen oxides contained in the exhaust gas discharged from the industrial equipment 13.

[0017] When modifying existing industrial equipment systems, to meet process requirements, fresh air 11 is heated by air-water heat exchanger 10, and then further heated by the existing heating system 12 before entering industrial equipment 13. For example, fresh air heated to 120°C by air-water heat exchanger 10 is further heated to 180°C by the existing heating system 12 to meet the conditions required for spray fluidization process.

[0018] The industrial equipment 13 is equipped with a blower at its inlet or an induced draft fan at its outlet, for providing the power required for the input of fresh air 11 or the discharge of low-temperature exhaust gas 5.

[0019] The system includes at least one heat pump unit; when there are multiple heat pump units, the connection between the multiple heat pump units is in series, in parallel, or a combination of series and parallel.

[0020] The water in the gas-water heat exchanger 10 and the fresh air 11 exchange heat indirectly. The heat exchange tubes of the gas-water heat exchanger 10 are made of bare tubes, finned tubes, or spiral grooved tubes.

[0021] The buffer tank 8 is equipped with an exhaust valve, a pressure gauge, and a safety valve.

[0022] For the parts not mentioned in this invention, existing technologies are used, that is, existing mature and reliable reasonable improvement measures can be introduced into this system, such as setting up necessary thermometers, hygrometers, heat preservation, bypass, automatic control facilities, etc., to control and adjust the temperature and humidity of fresh air and exhaust gas.

[0023] The present invention has the following advantages over the prior art:

[0024] 1. Energy saving: Using heat pumps and hot water systems as supporting units for industrial exhaust gas waste heat recovery systems, since the water in the hot water system can be regarded as an incompressible fluid, the power consumption of the circulating water pump is lower than the power consumption increased by extending the air duct, which can replace the existing technology and achieve better implementation results.

[0025] 2. Convenient and compact installation of air ducts and systems: The heat transferred and recovered by the heat medium water system can effectively save and utilize space. The air duct is simplified and concise, which effectively reduces air duct resistance and fan power consumption.

[0026] 3. High heat exchange efficiency: The gas-water heat exchanger 10 and condenser 2 are gas-liquid heat exchangers. Compared with the gas-gas heat exchanger of the prior art, their heat exchange coefficient is more than doubled. Therefore, the volume of the gas-water heat exchanger 10 and condenser 2 is reduced by more than half, the metal consumption of the heat exchanger is greatly reduced, and the heat exchange equipment is compact and efficient.

[0027] 4. Compared with existing technologies, this invention is particularly suitable for industrial exhaust gas waste heat recovery retrofit projects, has strong environmental adaptability, and is also applicable to new projects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an industrial exhaust gas waste heat recovery system according to the present invention.

[0029] Figure 1In the middle, 1-compressor, 2-condenser, 3-throttle valve, 4-evaporator, 5-low temperature exhaust gas, 6-liquid water, 7-steam trap, 8-buffer tank, 9-circulating water pump, 10-gas-water heat exchanger, 11-new air supply, 12-existing heating system, 13-industrial equipment, 14-purification equipment, 15-heat exchanger, 16-cold fluid, 17-hot fluid. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail with reference to specific embodiments.

[0031] Example 1:

[0032] An industrial exhaust gas waste heat recovery system includes a heat pump unit, a heat transfer medium water unit, and connecting pipelines. The heat pump unit includes a compressor 1, a condenser 2, a throttling valve 3, and an evaporator 4. The heat transfer medium water unit includes a circulating water pump 9, a gas-water heat exchanger 10, and a buffer tank 8.

[0033] Fresh air 11 is heated by the air-water heat exchanger 10 and the existing heating system 12 before entering the industrial equipment 13 for use by the industrial equipment 13. The humid exhaust gas discharged from the industrial equipment 13 is dehumidified and cooled by the purification equipment 14 and the evaporator 4 to form low-temperature exhaust gas 5 and liquid water 6 before being discharged.

[0034] The working fluid in the heat pump unit is pressurized and heated by the compressor 1, then heated by the condenser 2 to heat the water delivered by the circulating water pump 9. After cooling, the working fluid enters the evaporator 4 through the expansion valve 3, where it absorbs the heat from the humid exhaust gas discharged from the industrial equipment 13, and then enters the compressor 1 again, thus forming the working fluid circulation process of the heat pump unit.

[0035] Water pumped from the circulating water pump 9 is heated by the condenser 2 and then enters the air-water heat exchanger 10 to heat the fresh air 11. The low-temperature water from the air-water heat exchanger 10 returns to the circulating water pump 9 through the buffer tank 8, thus forming the water circulation process of the heat transfer medium water unit.

[0036] A steam trap 7 is provided: the humid exhaust gas discharged from the industrial equipment 13 is cooled by the evaporator 4, and the resulting condensate is discharged through the steam trap 7.

[0037] A heat exchanger 15 is provided: water pumped from the circulating water pump 9 is heated by the condenser 2, then enters the air-water heat exchanger 10 through the heat exchanger 15 to heat the fresh air 11. The low-temperature water exiting the air-water heat exchanger 10 returns to the circulating water pump 9, thus forming a water circulation process in the heat transfer medium water unit. The heat exchanger 15 is used to heat the cold fluid 16 into a hot fluid 17 or to provide external heating.

[0038] The industrial equipment 13 includes a drying tower, washing and drying equipment, coating and drying line, natural gas boiler, oil boiler, etc. The fresh air 11 is heated and used as a drying or combustion medium for the industrial equipment 13.

[0039] The purification device 14 is used to remove solid particles, sulfides, or nitrogen oxides contained in the humid exhaust gas discharged from the industrial equipment 13.

[0040] The industrial equipment 13 is equipped with a blower at its inlet or an induced draft fan at its outlet.

[0041] The system includes at least one heat pump unit; when there are multiple heat pump units, the connection between the multiple heat pump units is in series, in parallel, or a combination of series and parallel.

[0042] The water and fresh air 11 in the air-water heat exchanger 10 exchange heat indirectly, and the heat exchange tubes are made of bare tubes, finned tubes or spiral groove tubes, etc.

[0043] The buffer tank 8 is equipped with an exhaust valve, a pressure gauge, and a safety valve.

[0044] For the parts not mentioned in this invention, existing technologies are used, that is, existing mature and reliable reasonable improvement measures can be introduced into this system, such as setting up necessary thermometers, hygrometers, heat preservation, bypass, automatic control facilities, etc., to control and adjust the temperature and humidity of fresh air and exhaust gas.

[0045] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention, and these modifications and modifications also fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims of this application.

Claims

1. An industrial exhaust gas waste heat recovery system, characterized in that: The industrial exhaust gas waste heat recovery system includes a heat pump unit, a heat transfer water unit and their connecting pipes. The heat pump unit includes a compressor (1), a condenser (2), a throttle valve (3) and an evaporator (4). The heat transfer water unit includes a circulating water pump (9) and a gas-water heat exchanger (10). Fresh air (11) is heated by the air-water heat exchanger (10) and then enters the industrial equipment (13). The exhaust gas discharged from the industrial equipment (13) is cooled by the evaporator (4) and then discharged as low-temperature exhaust gas (5). The working fluid of the heat pump unit is pressurized and heated by the compressor (1), and then heated by the condenser (2) to heat the water delivered by the circulating water pump (9). After cooling, the working fluid enters the evaporator (4) through the throttle valve (3), absorbs the heat from the exhaust gas discharged from the industrial equipment (13), and then enters the compressor (1), thus forming the working fluid circulation process of the heat pump unit. Water pumped from the circulating water pump (9) is heated by the condenser (2) and then enters the air-water heat exchanger (10) to heat the fresh air (11). The low-temperature water from the air-water heat exchanger (10) returns to the circulating water pump (9), thus forming the water circulation process of the heat transfer water unit.

2. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: A buffer tank (8) is provided: the water sent from the circulating water pump (9) is heated by the condenser (2) and then enters the air-water heat exchanger (10) to heat the fresh air (11). The low-temperature water from the air-water heat exchanger (10) returns to the circulating water pump (9) through the buffer tank (8). Alternatively, the water sent from the circulating water pump (9) is heated by the buffer tank (8) and the condenser (2) and then enters the air-water heat exchanger (10) to heat the fresh air (11). The low-temperature water from the air-water heat exchanger (10) returns to the circulating water pump (9), thus forming the water circulation process of the heat transfer water unit.

3. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: The industrial equipment (13) includes a drying tower, a washing and drying equipment, a coating and drying line, a natural gas boiler, and an oil-fired boiler.

4. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: Purification equipment (14) is provided: the exhaust gas from the industrial equipment (13) enters the evaporator (4) through the purification equipment (14).

5. The industrial exhaust gas waste heat recovery system according to claim 4, characterized in that: The purification device (14) is used to remove solid particles, sulfides or nitrogen oxides contained in the exhaust gas discharged from the industrial equipment (13).

6. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: A heat exchanger (15) is provided: the water sent from the circulating water pump (9) is heated by the condenser (2) and then enters the gas-water heat exchanger (10) through the heat exchanger (15). The low-temperature water coming out of the gas-water heat exchanger (10) returns to the circulating water pump (9), thus forming the water circulation process of the heat transfer water unit.

7. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: The water and fresh air (11) in the gas-water heat exchanger (10) are exchanged indirectly. The heat exchange tubes of the gas-water heat exchanger (10) are plain tubes, finned tubes or spiral groove tubes.

8. The industrial exhaust gas waste heat recovery system according to claim 2, characterized in that: The buffer tank (8) is equipped with an exhaust valve, a pressure gauge and a safety valve.

9. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: The industrial equipment (13) is equipped with a blower at its inlet or an induced draft fan at its outlet.

10. The industrial exhaust gas waste heat recovery system according to claim 1, characterized in that: The system includes at least one heat pump unit; When there are multiple heat pump units, the connection between the multiple heat pump units can be in series, in parallel, or a combination of series and parallel.

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