Heat pump drying system of coating machine

Abstract

The invention discloses a coating machine heat pump drying system which comprises a fan, an air pipe and a second-stage recovery heat exchanger, one end of the air pipe is connected with the air outlet end of the fan, the air inlet end of the second-stage recovery heat exchanger is connected with the other end of the air pipe, one end of the second-stage recovery heat exchanger is connected with a multi-stage drying structure, and the other end of the second-stage recovery heat exchanger is connected with a heat exchanger. The other end of the secondary recovery heat exchanger is connected with an electric auxiliary heating structure; the invention relates to the technical field of coating machines, through multi-stage energy cascade organization and utilization, the drying power consumption of the coating machine is reduced by more than 20%, for the energy consumption of about 220kW coating machines, about 45kW energy is saved, 8 hours per day, 360 kilowatt-hour electricity, 300 days per year and 10.8 million kilowatt-hour electricity are saved, the energy-saving effect is remarkable, the energy cascade organization is adopted, and the energy consumption is reduced. And meanwhile, due to the combined nozzles, the drying temperature and humidity of a coated product are more uniform and stable, the product quality is improved, and the quality and efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of coating machines, in particular to a heat pump drying system of a coating machine. Background Art

[0002] The printing industry and some battery industries need to use coating machines. Coating machines consume a lot of electricity, and the largest energy consumption is in the drying system. After the coating machine coats the substrate, its organic solvent needs to be dried. At present, the combined heating method is used as shown in the figure below, and the thermal efficiency of electric heating is generally only 0.82, which is a great waste of energy.

[0003] The main problems of the existing technology are: (1) The efficiency of electric heating is low and the electric power is large. Since the heat release area of ​​the electric heater is limited, it affects the temperature rise rate of the hot air, so the electric power required exceeds the actual need; (2) The heat source is steam or infrared combined heating, and heat recovery is appropriately considered, but the overall thermal efficiency is still not high; (3) Because the drying efficiency is not high, it has a great impact on the quality. For example, the hot air speed of the imported oven nozzle reaches 30-35m / s, but the hot air speed at the hot air nozzle of most domestic coating machines can reach a maximum of 15-20m / s, which seriously affects the drying effect; (4) Since each stage of heat recovery uses fresh air and exhaust gas heat exchange, there is still a large amount of energy that has not been recovered in the exhaust after recovery, resulting in waste. For example, the exhaust gas discharged from the second stage is greater than 60°C, while the exhaust gas temperature from the fourth stage can be as high as 90°C. It is obviously unreasonable to discharge directly at such a temperature. In view of this, in-depth research was conducted on the above problems, and this case was created. Summary of the invention

[0004] The technical solution of the present invention to achieve the above-mentioned purpose is: a heat pump drying system for a coating machine, comprising a fan, an air duct and a secondary recovery heat exchanger, one end of the air duct is connected to the air outlet of the fan, the air inlet of the secondary recovery heat exchanger is connected to the other end of the air duct, one end of the secondary recovery heat exchanger is connected to a multi-stage drying structure, and the other end of the secondary recovery heat exchanger is connected to an electric auxiliary heating structure;

[0005] The multi-stage drying structure comprises: a first connecting pipe, a first multi-stream heat exchanger, a first air inlet pipe, a first drying box, a second connecting pipe, a second multi-stream heat exchanger, a second air inlet pipe, a second drying box, a third connecting pipe, a third multi-stream heat exchanger, a third air inlet pipe, a third drying box, a fourth connecting pipe, a fourth multi-stream heat exchanger, a fourth air inlet pipe, a fourth drying box and a recovery component;

[0006] One end of the first connecting pipe is connected to the air outlet end of the secondary recovery heat exchanger, one end of the first multi-stream heat exchanger is connected to the other end of the first connecting pipe, one end of the first air inlet pipe is connected to one end of the first multi-stream heat exchanger, the air inlet end of the first drying box is connected to one end of the first connecting pipe, one end of the second connecting pipe is connected to one end of the first air inlet pipe, one end of the second multi-stream heat exchanger is connected to the other end of the second connecting pipe, one end of the second air inlet pipe is connected to one end of the second multi-stream heat exchanger, the air inlet end of the second drying box is connected to one end of the second connecting pipe, one end of the third connecting pipe is connected to one end of the second air inlet pipe, and the third multi-stream heat exchanger is connected to one end of the second air inlet pipe. One end of the heat exchanger is connected to the other end of the third connecting pipe, one end of the third air inlet pipe is connected to one end of the third multi-stream heat exchanger, the air inlet end of the third drying box is connected to one end of the third connecting pipe, one end of the fourth connecting pipe is connected to one end of the third air inlet pipe, one end of the fourth multi-stream heat exchanger is connected to the other end of the fourth connecting pipe, one end of the fourth air inlet pipe is connected to one end of the fourth multi-stream heat exchanger, the air inlet end of the fourth drying box is connected to one end of the fourth connecting pipe, one end of the recovery component is respectively connected to the air outlet ends of the first drying box, the second drying box, the third drying box and the fourth drying box, and the other end is connected to the secondary recovery heat exchanger.

[0007] Preferably, the first drying box comprises: a hot air inlet, an air distribution plate and a plurality of nozzles;

[0008] The hot air inlet is located at the upper end of the first drying box, the air distribution plate is installed in the first drying box, and the plurality of nozzles are embedded in the lower wall of the first drying box.

[0009] Preferably, the recovery assembly comprises: a first recovery pipe, a second recovery pipe, a third recovery pipe and a fourth recovery pipe;

[0010] One end of the first recovery pipe is connected to one side of the first drying box, and the other end passes through the first multi-stream heat exchanger and is connected to the secondary recovery heat exchanger. One end of the second recovery pipe is connected to one side of the second drying box, and the other end passes through the second multi-stream heat exchanger and the first multi-stream heat exchanger, and is connected to the secondary recovery heat exchanger. One end of the third recovery pipe is connected to one side of the third drying box, and the other end passes through the third multi-stream heat exchanger, the second multi-stream heat exchanger and the first multi-stream heat exchanger, and is connected to the secondary recovery heat exchanger. One end of the fourth recovery pipe is connected to one side of the fourth drying box, and the other end passes through the fourth multi-stream heat exchanger, the third multi-stream heat exchanger, the second multi-stream heat exchanger and the first multi-stream heat exchanger, and is connected to the secondary recovery heat exchanger.

[0011] Preferably, the electric auxiliary heating structure comprises: an exhaust heat exchanger, a heat pump evaporator, a compressor, a first heat pump condenser, a second heat pump condenser, a third heat pump condenser and a fourth heat pump condenser;

[0012] One end of the exhaust heat exchanger is connected to the air outlet end of the secondary recovery heat exchanger, one end of the heat pump evaporator is connected to the exhaust heat exchanger, one end of the compressor is connected to the heat pump evaporator, the first heat pump condenser is located at the lower end of the first drying box, the second heat pump condenser is located at the lower end of the second drying box, the third heat pump condenser is located at the lower end of the third drying box, the fourth heat pump condenser is located at the lower end of the fourth drying box, and the first heat pump condenser, the second heat pump condenser, the third heat pump condenser and the fourth heat pump condenser are all connected to the heat pump evaporator and the compressor.

[0013] Preferably, the plurality of nozzles are composed of a combination of an annular slot nozzle, a wall nozzle, a circular nozzle and a multi-hole nozzle.

[0014] Preferably, the plurality of spray groups are arranged along the coating movement direction with the nozzle air output from large to small.

[0015] Preferably, one side of the exhaust heat exchanger is connected to an exhaust pipe.

[0016] Preferably, the temperatures of the first drying box, the second drying box, the third drying box and the fourth drying box are gradually increased.

[0017] A coating machine heat pump drying system is manufactured using the technical solution of the present invention. The multi-stage drying structure and electric auxiliary heating structure adopted in this case have the following advantages: (1) Multi-stream heat exchangers are used for heat recovery: small plate-fin heat exchangers are used to recover heat energy; Section 1, Section 2, and Section 3 heat recovery regenerators are all multi-stream heat exchangers. The plate-fin heat exchanger is compact, and multi-stage plate heat exchangers can also be used for modular cascading to achieve the effect of plate-fin heat exchangers; (2) Energy cascade organization of heat supply based on the main heat source high-temperature heat pump: Energy cascade utilization is an important technical measure and means to improve energy efficiency, save energy and reduce emissions. After matching and recycling each level of energy supply, secondary recovery is continued. On the basis of secondary recovery, it is finally used to improve the environment of the heat pump evaporator to improve the efficiency and performance of the heat pump cycle. It is to repeatedly explore the energy cascade, reduce irreversible temperature difference heat transfer losses, and maximize the use of thermal energy; (3) An air distribution plate is added to the air supply box of the drying box, and a combined nozzle is used for the nozzle. That is, as the direction of movement of the coated product changes, its temperature and humidity gradually change after being heated and dried. Different air volumes are supplied in response to the changes in the temperature and humidity of the coated material, so as to couple the required air volume and achieve a stable and uniform drying temperature and humidity of the coated product, which is beneficial to improving product quality. (4) Energy saving: Through multi-level energy ladder organization and utilization, the drying power consumption of the coating machine is reduced by more than 20%. For a coating machine with an energy consumption of about 220kW, it is about 45kW of energy saving. 8 hours a day, 360 degrees of electricity are saved, 300 days a year, 108,000 degrees of electricity, and the energy saving effect is significant. (5) Improve the drying quality of the coated product: The energy ladder organization is more conducive to the coupling of the temperature rise amplitude and the temperature rise rate, and can effectively increase the jet speed. At the same time, due to the combined nozzle, it is more conducive to the uniform and stable drying temperature and humidity of the coated product, improving product quality and increasing quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic block diagram of the structural relationship of a heat pump drying system for a coating machine.

[0019] Figure 2 The present invention is a schematic diagram of the drying box structure of a heat pump drying system for a coating machine.

[0020] In the figure: 1, fan, 2, air duct, 3, secondary recovery heat exchanger, 4, first connecting pipe, 5, first multi-stream heat exchanger, 6, first air inlet pipe, 7, first drying box, 8, second connecting pipe, 9, second multi-stream heat exchanger, 10, second air inlet pipe, 11, second drying box, 12, third connecting pipe, 13, third multi-stream heat exchanger, 14, third air inlet pipe, 15, third drying box, 16, fourth connecting pipe, 17, fourth multi-stream heat exchanger device, 18. fourth air inlet pipe, 19. fourth drying box, 20. hot air inlet, 21. air distribution plate, 22. nozzle, 23. first recovery pipe, 24. second recovery pipe, 25. third recovery pipe, 26. fourth recovery pipe, 27. exhaust heat exchanger, 28. heat pump evaporator, 29. compressor, 30. first heat pump condenser, 31. second heat pump condenser, 32. third heat pump condenser, 33. fourth heat pump condenser, 34. exhaust pipe. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below in conjunction with the accompanying drawings. Figure 1-2 As shown, a heat pump drying system for a coating machine.

[0022] Embodiment: A coating machine heat pump drying system includes a fan 1, an air duct 2 and a secondary recovery heat exchanger 3, one end of the air duct 2 is connected to the air outlet of the fan 1, the air inlet end of the secondary recovery heat exchanger 3 is connected to the other end of the air duct 2, one end of the secondary recovery heat exchanger 3 is connected to a multi-stage drying structure, and the other end of the secondary recovery heat exchanger 3 is connected to an electric auxiliary heating structure; the multi-stage drying structure includes: a first connecting pipe 4, a first multi-stream heat exchanger 5, a first air inlet pipe 6, a first drying box 7, a second connecting pipe 8, a second multi-stream heat exchanger 9, a second air inlet pipe 10, a second drying box 11, a third connecting pipe 12, a third multi-stream heat exchanger 13, A third air inlet pipe 14, a third drying box 15, a fourth connecting pipe 16, a fourth multi-stream heat exchanger 17, a fourth air inlet pipe 18, a fourth drying box 19 and a recovery component; one end of the first connecting pipe 4 is connected to the air outlet end of the secondary recovery heat exchanger 3, one end of the first multi-stream heat exchanger 5 is connected to the other end of the first connecting pipe 4, one end of the first air inlet pipe 6 is connected to one end of the first multi-stream heat exchanger 5, the air inlet end of the first drying box 7 is connected to one end of the first connecting pipe 4, one end of the second connecting pipe 8 is connected to one end of the first air inlet pipe 6, one end of the second multi-stream heat exchanger 9 is connected to the other end of the second connecting pipe 8, and one end of the second air inlet pipe 10 is connected to the second multi-stream heat exchanger 10. The air inlet end of the third drying box 11 is connected to one end of the second connecting pipe 8, one end of the third connecting pipe 12 is connected to one end of the second air inlet pipe 10, one end of the third multi-stream heat exchanger 13 is connected to the other end of the third connecting pipe 12, one end of the third air inlet pipe 14 is connected to one end of the third multi-stream heat exchanger 13, the air inlet end of the third drying box 15 is connected to one end of the third connecting pipe 12, one end of the fourth connecting pipe 16 is connected to one end of the third air inlet pipe 14, one end of the fourth multi-stream heat exchanger 17 is connected to the other end of the fourth connecting pipe 16, one end of the fourth air inlet pipe 18 is connected to one end of the fourth multi-stream heat exchanger 17, and the fourth drying box 15 is connected to one end of the third connecting pipe 12. The air inlet end of the drying box 19 is connected to one end of the fourth connecting pipe 16, one end of the recovery component is respectively connected to the air outlet ends of the first drying box 7, the second drying box 11, the third drying box 15 and the fourth drying box 19, and the other end is connected to the secondary recovery heat exchanger 3. The first drying box 7 includes: a hot air inlet 20, an air distribution plate 21 and a plurality of nozzles 22; the hot air inlet 20 is located at the upper end of the first drying box 7, the air distribution plate 21 is installed in the first drying box 7, and the plurality of nozzles 22 are embedded in the lower wall of the first drying box 7. The recovery component includes: a first recovery pipe 23, a second recovery pipe 24, a third recovery pipe 25 and a fourth recovery pipe 26;One end of the first recovery pipe 23 is connected to one side of the first drying box 7, and the other end passes through the first multi-stream heat exchanger 5 and is connected to the secondary recovery heat exchanger 3. One end of the second recovery pipe 24 is connected to one side of the second drying box 11, and the other end passes through the second multi-stream heat exchanger 9 and the first multi-stream heat exchanger 5, and is connected to the secondary recovery heat exchanger 3. One end of the third recovery pipe 25 is connected to one side of the third drying box 15, and the other end passes through the third multi-stream heat exchanger 13, the second multi-stream heat exchanger 9 and the first multi-stream heat exchanger 5. The fourth recovery pipe 26 is connected to the fourth drying box 19 at one end, and the other end passes through the fourth multi-stream heat exchanger 17, the third multi-stream heat exchanger 13, the second multi-stream heat exchanger 9 and the first multi-stream heat exchanger 5, and is connected to the secondary recovery heat exchanger 3. The electric auxiliary heating structure includes: an exhaust heat exchanger 27, a heat pump evaporator 28, a compressor 29, a first heat pump condenser 30, a second heat pump condenser 31, a third heat pump condenser 32 and a Four heat pump condensers 33; one end of the exhaust heat exchanger 27 is connected to the outlet end of the secondary recovery heat exchanger 3, one end of the heat pump evaporator 28 is connected to the exhaust heat exchanger 27, one end of the compressor 29 is connected to the heat pump evaporator 28, the first heat pump condenser 30 is located at the lower end of the first drying box 7, the second heat pump condenser 31 is located at the lower end of the second drying box 11, the third heat pump condenser 32 is located at the lower end of the third drying box 15, the fourth heat pump condenser 33 is located at the lower end of the fourth drying box 19, the first heat pump condenser 30, the second heat pump The condenser 31, the third heat pump condenser 32 and the fourth heat pump condenser 33 are all connected to the heat pump evaporator 28 and the compressor 29. The plurality of nozzles 22 are composed of annular slit nozzles 22, wall nozzles 22, circular nozzles 22 and multi-hole nozzles 22. The plurality of spray groups are arranged along the coating movement direction, and the nozzles 22 are arranged from large to small in terms of gas output. An exhaust pipe 34 is connected to one side of the exhaust heat exchanger 27. The temperatures of the first drying box 7, the second drying box 11, the third drying box 15 and the fourth drying box 19 are gradually increased. ;

[0023] It should be noted that the total air volume required by the entire coating machine is sent to the secondary recovery heat exchanger 3 through the fan 1, and the exhaust gas of the first drying box 7, the second drying box 11, the third drying box 15 and the fourth drying box 19 is recycled at the secondary level. The flow channel is arranged in a countercurrent organization, and the low-temperature exhaust gas is first heated as fresh air, and gradually reaches the last stage of exhaust gas. The temperature of the outgoing air flow is close to the first stage temperature requirement, and then passes through the first multi-stream heat exchanger 5. After coming out, the air volume is divided according to the air volume requirement of the first drying box 7 and sent to the circulating air duct of the first drying box 7. If the temperature requirement is met, it is directly sent to the first drying box 7 for hot air drying of the coating material. If the temperature is not enough, the circulating air duct air flow is heated by the first heat pump condenser 30. After the temperature requirement is met, the coating material in the first drying box 7 is dried. Drying is performed. Generally, the electric auxiliary heating arranged on the first heat pump condenser 30 is not used. It is only set for production safety to prevent the heat pump condensing heater from malfunctioning. The total incoming air is recovered by the secondary recovery heat exchanger 3. After being heated by the first multi-stream heat exchanger 5, except for the air volume required by the first drying box 7, the other air flows are all sent to the second multi-stream heat exchanger 9. After heating, since the temperature required by the second drying box 11 is only about 20°C higher than the required temperature of the first drying box 7, and the heat regenerator also has the third multi-stream heat exchanger 13 and the fourth multi-stream heat exchanger 17 to heat it, usually, the multi-stream heat exchanger that passes through the secondary heat recovery device and then the second drying box 11 can meet the temperature requirement of the second drying box 11, because there is not only its own The waste gas heat recovery is also carried out in the third drying box 15 and the fourth drying box 19. The temperature of the third drying box 15 and the fourth drying box 19 is much higher than that of the second drying box 11. For example, the third drying box 15 is 30°C higher than the second drying box 11, and the fourth drying box 19 is 20°C higher than the third drying box 15. There are temperature differences of 30°C and 50°C respectively, which are enough to heat the airflow to the required temperature of the second drying box 11. If it is slightly insufficient, it is heated by the second heat pump condensing heater. Similarly, the power-saving auxiliary heating is only used as a backup for production safety. The airflow coming out of the second multi-stream heat exchanger 9, except for the air volume distributed to the second drying box 11, is all sent to the third multi-stream heat exchanger 13. The third multi-stream heat exchanger 13 not only recovers The waste gas heat of the third drying box 15 also recovers the heat of the fourth drying box 19. After heat recovery, the insufficient heat is provided by the third heat pump condensation heater and electric auxiliary or other heat sources. When it reaches the third drying box 15, because the required temperature is high, the heat pump does not work most of the time. If it is not used, the third and fourth heat pump condensers 33 can be cancelled. They are only set for some drying requirements with a drying temperature not exceeding 85°C. The airflow coming out of the third multi-stream heat exchanger 13, except for the airflow distributed to the third drying box 15, all enters the fourth multi-stream heat exchanger 17, and is sent to the fourth drying box 19 after heat recovery. The insufficient heat is heated by the electric auxiliary or other heat sources through the circulation duct of the fourth drying box 19. At this time, the fourth heat pump condensation heater is basically not used.The upper limit of the heating temperature of the fourth heat pump condensing heater is set lower than 85°C. If it exceeds 85°C, the fourth heat pump condensing heater is not set. The exhaust gas from the secondary recovery heat exchanger 3 further serves the heat pump evaporator 28. Through a simple cross-flow two-channel heat recovery device, the air is heated and then goes through exhaust gas recovery or adsorption treatment. After reaching the standard, it is emptied. The heat pump evaporator 28 recovers the exhaust gas heat and changes the ambient temperature or heat exchange temperature of the heat pump evaporator 28 to improve performance, improve the compressor 29 pressure ratio, improve the compressor 29 operating conditions, and improve the heat pump system performance CO P, further energy saving and emission reduction, the electric auxiliary heating structure has another function, which is to start in advance before coating and drying, preheat each drying box to about 50°C, and then carry out normal coating and drying according to the heating temperature, air volume and temperature rise rate required by the coating process, that is, after each stage reaches the basic temperature of 50°C, the electric auxiliary or other heat source is started for each stage to meet the coating and drying process requirements. After normal operation, these heat regenerators will work better, so that the first drying box 7 and the second drying box 11 basically do not need heat energy supply, and the third drying box 15 and the fourth drying box 19 only have a small amount of heat energy. Electric auxiliary or other heat sources are used for heat supply. An air distribution plate 21 is used on the box body. It is still necessary for large-scale coating machines to use air distribution. Secondly, the uniform structure of the nozzle 22 is conducive to processing. However, when the coated substrate passes through the oven, the temperature and humidity of different parts are actually different. Therefore, the use of nozzles 22 with different structures corresponding to the air volume is conducive to more reasonable drying of the organic solvent of the coating, and stress is not formed between each other. Therefore, the nozzle 22 adopts a combined structure, which is composed of an annular slit nozzle 22, a wall-attached nozzle 22, a circular nozzle 22 and a porous nozzle 22. Along the direction of coating movement, the nozzle with large air flow is arranged first. 22, gradually reduce the air volume of the nozzle 22 combination, in addition, due to heat recovery and heat pump heating, the temperature rise rate is increased, and a higher speed hot air flow can be used for heating and drying, which is beneficial to improve the drying quality and the quality of the coated product. The electric auxiliary heating structure needs to prevent high pressure from exceeding the standard. The latest high-pressure ratio scroll compressor 29 is used to increase the high pressure that the compressor 29 can withstand. At the same time, an ejector is built before the suction buffer tank to introduce part of the exhaust gas into the ejector and mix it with the refrigerant vapor from the evaporator to obtain a suitable intake temperature and pressure, and improve the heat pump pressure ratio and cycle efficiency.

[0024] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present invention. Some changes that may be made to certain parts thereof by technicians in this technical field all reflect the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A heat pump drying system for a coating machine, comprising a fan (1), an air duct (2) and a secondary recovery heat exchanger (3), characterized in that: One end of the air duct (2) is connected to the air outlet end of the fan (1), the air inlet end of the secondary recovery heat exchanger (3) is connected to the other end of the air duct (2), one end of the secondary recovery heat exchanger (3) is connected to a multi-stage drying structure, and the other end of the secondary recovery heat exchanger (3) is connected to an electric auxiliary heating structure; The multi-stage drying structure comprises: a first connecting pipe (4), a first multi-stream heat exchanger (5), a first air inlet pipe (6), a first drying box (7), a second connecting pipe (8), a second multi-stream heat exchanger (9), a second air inlet pipe (10), a second drying box (11), a third connecting pipe (12), a third multi-stream heat exchanger (13), a third air inlet pipe (14), a third drying box (15), a fourth connecting pipe (16), a fourth multi-stream heat exchanger (17), a fourth air inlet pipe (18), a fourth drying box (19) and a recovery component; One end of the first connecting pipe (4) is connected to the outlet end of the secondary recovery heat exchanger (3); one end of the first multi-stream heat exchanger (5) is connected to the other end of the first connecting pipe (4); one end of the first air inlet pipe (6) is connected to one end of the first multi-stream heat exchanger (5); the air inlet end of the first drying box (7) is connected to one end of the first connecting pipe (4); one end of the second connecting pipe (8) is connected to one end of the first air inlet pipe (6); one end of the second multi-stream heat exchanger (9) is connected to the other end of the second connecting pipe (8); one end of the second air inlet pipe (10) is connected to one end of the second multi-stream heat exchanger (9); the air inlet end of the second drying box (11) is connected to one end of the second connecting pipe (8); one end of the third connecting pipe (12) is connected to one end of the second air inlet pipe (10); one end of the third multi-stream heat exchanger (13) is connected to one end of the second air inlet pipe (13); An end of the third connecting pipe (12) is connected to the other end of the third connecting pipe (12), one end of the third air inlet pipe (14) is connected to one end of the third multi-stream heat exchanger (13), an air inlet end of the third drying box (15) is connected to one end of the third connecting pipe (12), one end of the fourth connecting pipe (16) is connected to one end of the third air inlet pipe (14), one end of the fourth multi-stream heat exchanger (17) is connected to the other end of the fourth connecting pipe (16), one end of the fourth air inlet pipe (18) is connected to one end of the fourth multi-stream heat exchanger (17), an air inlet end of the fourth drying box (19) is connected to one end of the fourth connecting pipe (16), one end of the recovery component is respectively connected to the air outlet ends of the first drying box (7), the second drying box (11), the third drying box (15) and the fourth drying box (19), and the other end is connected to the secondary recovery heat exchanger (3).

2. A coating machine heat pump drying system according to claim 1, characterized in that: The first drying box (7) comprises: a hot air inlet (20), an air distribution plate (21) and a plurality of nozzles (22); The hot air inlet (20) is located at the upper end of the first drying box (7), the air distribution plate (21) is installed in the first drying box (7), and the plurality of nozzles (22) are embedded in the lower wall of the first drying box (7).

3. A coating machine heat pump drying system according to claim 1, characterized in that: The recovery component comprises: a first recovery pipe (23), a second recovery pipe (24), a third recovery pipe (25) and a fourth recovery pipe (26); One end of the first recovery pipe (23) is connected to one side of the first drying box (7), and the other end thereof passes through the first multi-stream heat exchanger (5) and is connected to the secondary recovery heat exchanger (3); one end of the second recovery pipe (24) is connected to one side of the second drying box (11), and the other end thereof passes through the second multi-stream heat exchanger (9) and the first multi-stream heat exchanger (5), and is connected to the secondary recovery heat exchanger (3); one end of the third recovery pipe (25) is connected to one side of the third drying box (15); One end of the fourth recovery pipe (26) is connected to one side of the fourth drying box (19), and the other end thereof passes through the fourth multi-stream heat exchanger (17), the third multi-stream heat exchanger (13), the second multi-stream heat exchanger (9) and the first multi-stream heat exchanger (5), and is connected to the secondary recovery heat exchanger (3). One end of the fourth recovery pipe (26) is connected to one side of the fourth drying box (19), and the other end thereof passes through the fourth multi-stream heat exchanger (17), the third multi-stream heat exchanger (13), the second multi-stream heat exchanger (9) and the first multi-stream heat exchanger (5), and is connected to the secondary recovery heat exchanger (3).

4. A coating machine heat pump drying system according to claim 1, characterized in that: The electric auxiliary heating structure comprises: an exhaust heat exchanger (27), a heat pump evaporator (28), a compressor (29), a first heat pump condenser (30), a second heat pump condenser (31), a third heat pump condenser (32) and a fourth heat pump condenser (33); One end of the exhaust heat exchanger (27) is connected to the air outlet end of the secondary recovery heat exchanger (3); one end of the heat pump evaporator (28) is connected to the exhaust heat exchanger (27); one end of the compressor (29) is connected to the heat pump evaporator (28); the first heat pump condenser (30) is located at the lower end of the first drying box (7); the second heat pump condenser (31) is located at the lower end of the second drying box (11); the third heat pump condenser (32) is located at the lower end of the third drying box (15); the fourth heat pump condenser (33) is located at the lower end of the fourth drying box (19); the first heat pump condenser (30), the second heat pump condenser (31), the third heat pump condenser (32) and the fourth heat pump condenser (33) are all connected to the heat pump evaporator (28) and the compressor (29).

5. A coating machine heat pump drying system according to claim 2, characterized in that: The plurality of nozzles (22) are composed of a ring-shaped slot nozzle (22), a wall-attached nozzle (22), a circular nozzle (22) and a multi-hole nozzle (22).

6. A coating machine heat pump drying system according to claim 2, characterized in that: The plurality of spray groups are arranged along the coating movement direction, with the nozzles (22) having air outputs from large to small.

7. A coating machine heat pump drying system according to claim 4, characterized in that: An exhaust pipe (34) is connected to one side of the exhaust heat exchanger (27).

8. A coating machine heat pump drying system according to claim 1, characterized in that: The temperatures of the first drying box (7), the second drying box (11), the third drying box (15) and the fourth drying box (19) gradually increase.

Images