A high-temperature heat pump drying system with a wide temperature range

Abstract

The present invention discloses a high-temperature heat pump drying system with a wide temperature range, which relates to the field of heating and drying. The aim is to solve the problem that the operating temperature of the existing drying system has great limitations, resulting in low equipment utilization rate. The system includes a heat pump heating module, which is respectively connected to a refrigerant recovery module and a drying module. The heating mode conversion of the heat pump heating module is realized through the refrigerant recovery module; the drying module includes a waste heat heat exchanger and a number of regulating valves communicated with the waste heat heat exchanger. The switching of the drying mode of the drying module is realized by the movement of the wind deflector of the regulating valve. The high-temperature heat pump drying system with a wide temperature range of the present invention can realize the efficient and safe operation of the heat pump under the drying temperature conditions of 30~200°C, improve the availability of the equipment, and has a wider application range.

Description

Technical Field

[0001] The present invention relates to the field of heating and drying, and particularly to a high-temperature heat pump drying system with a wide temperature range. Background Art

[0002] Traditional drying systems use electric heating, steam or hot water as heat sources, which have the problems of high energy consumption and high operating costs, and do not meet the energy dual-carbon development goals. Drying systems based on heat pump technology are already relatively mature, but are generally applied to scenarios with relatively low drying temperatures. When the drying temperature is relatively high, there are problems such as the evaporation temperature / compressor operating temperature exceeding the specified upper limit and the condensation temperature not being able to accurately reach the set temperature. When the drying return air temperature is relatively low, there is a temperature at which the heat pump system cannot operate due to low condensation pressure. In addition, the operating temperature of existing drying systems has great limitations, resulting in low equipment utilization rate and reduced economy.

[0003] Although the Chinese patent with the publication number CN209605504U can improve the heat utilization rate, its operating temperature has great limitations and cannot solve the above existing problems. Summary of the Invention

[0004] The present invention solves the problem that the operating temperature of existing drying systems has great limitations, which will result in low equipment utilization rate, and proposes a high-temperature heat pump drying system with a wide temperature range, which can realize the efficient and safe operation of the heat pump under the drying temperature conditions of 30~200°C, improve the availability of the equipment, and have a wider application range.

[0005] To achieve the above object, the present invention adopts the following technical solution: A high-temperature heat pump drying system with a wide temperature range includes a heat pump heating module, which is respectively connected to a refrigerant recovery module and a drying module, and the heating mode conversion of the heat pump heating module is realized through the refrigerant recovery module; the drying module includes a waste heat heat exchanger and a number of regulating valves communicated with the waste heat heat exchanger, and the switching of the drying mode of the drying module is realized by the movement of the wind deflector of the regulating valve.

[0006] This technical solution mainly includes a heat pump heating module, a refrigerant recovery module and a drying module; the system of the present invention can achieve a temperature control range of 30~200°C, a minimum relative humidity of 15%, a change in heating power of 20%~100%, and can select an open or closed drying mode according to the cleanliness of the material drying gas. Compared with traditional drying systems, it has a wider application range.

[0007] The present invention is further configured as: The refrigerant recovery module includes three groups of refrigerant recovery units, and each group of refrigerant recovery units includes an air storage tank, a suction pump and a solenoid valve connected to the air storage tank in sequence.

[0008] In this technical solution, the three groups of refrigerant recovery units are a low-temperature refrigerant recovery unit, a medium-temperature refrigerant recovery unit, and a high-temperature refrigerant recovery unit. Refrigerant media with different operating temperatures are stored in the gas storage tanks of the three units.

[0009] The present invention is further configured as follows: The heat pump heating module includes a solar collector and a first air-cooled evaporator. One end of the solar collector is connected to a second electronic expansion valve, and one end of the first air-cooled evaporator is connected to a first electronic expansion valve. The other ends of the solar collector and the first air-cooled evaporator are both connected to a gas-liquid separator.

[0010] In this technical solution, in the dual-source heating mode, the low-temperature and low-pressure refrigerant enters the first air-cooled evaporator and the solar collector to absorb heat and turn into low-temperature and low-pressure superheated steam.

[0011] The present invention is further configured as follows: The heat pump heating module includes a second air-cooled evaporator and a third air-cooled evaporator. One end of the second air-cooled evaporator is connected to a fourth solenoid valve, and one end of the third air-cooled evaporator is connected to a fifth solenoid valve. The other ends of the second air-cooled evaporator and the third air-cooled evaporator are both connected to a gas-liquid separator.

[0012] In this technical solution, the low-temperature and low-pressure refrigerant enters the second air-cooled evaporator and the third air-cooled evaporator to absorb heat and turn into low-pressure superheated steam.

[0013] The present invention is further configured as follows: One end of the gas-liquid separator is connected to a compressor, the other end of the compressor is connected to an air-cooled condenser, the other end of the air-cooled condenser is connected to a liquid storage tank, the other end of the liquid storage tank is connected to an economizer, and the other end of the economizer is connected to a filter.

[0014] In this technical solution, the low-temperature and low-pressure superheated refrigerant enters the compressor after passing through the gas-liquid separator, then turns into a high-temperature and high-pressure refrigerant, enters the air-cooled condenser to heat the air (the air can be heated to 30 - 75°C), cools down and turns into a high-pressure and medium-temperature refrigerant, then enters the liquid storage tank, then enters the economizer, and then enters the filter.

[0015] The present invention is further configured as follows: A sixth solenoid valve and a fluorine pump are provided between the liquid storage tank and the economizer, the sixth solenoid valve and the fluorine pump are in parallel, a third electronic expansion valve is provided between the economizer and the filter, and the economizer is also connected to the compressor.

[0016] In this technical solution, the high-pressure and medium-temperature refrigerant enters the liquid storage tank, then enters the economizer, then enters the filter, and is divided into two branches. One branch enters the second air-cooled evaporator and the third air-cooled evaporator to continue the previous process, and the other branch passes through the third electronic expansion valve for throttling, and then enters the economizer to be heated and evaporated. The opening degree of the third electronic expansion valve is automatically adjusted according to the superheat degree of the refrigerant at the economizer outlet (the setting range is 2-10 °C), and then the refrigerant enters the compressor.

[0017] The present invention is further configured as: the two ends of the air-cooled condenser are respectively connected with a first fan and an electric heater, and the other end of the electric heater is connected with a drying chamber.

[0018] In this technical solution, in the rapid start-up stage of the electric heating for high-temperature heating, the first fan, the second fan, and the electric heater are turned on until the temperature measured by the third temperature sensor reaches 85 °C, and then the electric heater stops working.

[0019] The present invention is further configured as: the control valve of the drying module includes a second three-way valve and a first three-way valve connected to the second three-way valve. The second three-way valve and the first three-way valve are both provided with wind deflectors, and the wind deflectors can be adjusted by moving; the first three-way valve is also connected to the second air-cooled evaporator and the third air-cooled evaporator through a waste heat exchanger or directly.

[0020] In this technical solution, after the air enters the drying chamber and is cooled by absorbing heat from the object to be dried, it passes through the second three-way valve. The second three-way valve has a wind deflector that can move up and down, and its position is adjusted according to the difference between the temperature measured by the third temperature sensor and the upper limit of the allowable operating temperature of the compressor.

[0021] The present invention is further configured as: the control valve of the drying module further includes a switching valve, and the switching valve is provided with a wind deflector that can move left and right.

[0022] In this technical solution, in the conventional humidity control mode, the left end of the wind deflector is located at the left dead point D, and when in the high-precision humidity control mode, the right end of the wind deflector is located at the right dead point E.

[0023] The present invention is further configured as: the drying chamber is respectively connected with an exhaust valve and an intake valve, and the intake valve is connected to the third temperature sensor.

[0024] In this technical solution, in the open drying mode, the ambient air passes through the intake valve, is then sent by the first fan to the air-cooled condenser to be heated, then enters the hot air supply air duct, and is sent into the drying chamber from the air duct air outlet. After being cooled by absorbing heat from the material to be dried, it is discharged through the exhaust valve.

[0025] The present invention can bring the following beneficial effects:

[0026] A high-temperature heat pump drying system with a wide temperature range according to the present invention can achieve efficient and safe operation of the heat pump under drying temperature conditions of 30 to 200 °C, improve the availability of the equipment, and has a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall schematic diagram of a high-temperature heat pump drying system with a wide temperature range of the present application.

[0028] Figure 2 It is a schematic diagram of the air flow direction of the conventional humidity control mode in the closed drying mode of the present application.

[0029] Figure 3 It is a schematic diagram of the air flow direction of the high-precision humidity control mode in the closed drying mode of the present application.

[0030] Figure 4 It is a schematic diagram of the air flow direction of the open drying mode of the present application.

[0031] REFERENCE MARKS:

[0032] First gas storage tank 1, first air extraction pump 2, first solenoid valve 3, second gas storage tank 4, second air extraction pump 5, second solenoid valve 6, third gas storage tank 7, third air extraction pump 8, third solenoid valve 9, first electronic expansion valve 10, second electronic expansion valve 11, first air-cooled evaporator 12, solar collector 13, first temperature sensor 14, first pressure sensor 15, second temperature sensor 16, second pressure sensor 17, fourth solenoid valve 18, second air-cooled evaporator 19, first drain pipe 20, fifth solenoid valve 21, third air-cooled evaporator 22, waste heat exchanger 23, second drain pipe 24, first three-way valve 25, second three-way valve 26, third temperature sensor 27, first fan 28, air-cooled condenser 29, electric heater 30, fourth temperature sensor 31, gas-liquid separator 32, compressor 33, liquid storage tank 34, sixth solenoid valve 35, fluorine pump 36, fifth temperature sensor 37, third pressure sensor 38, sixth temperature sensor 39, fourth pressure sensor 40, economizer 41, third electronic expansion valve 42, filter 43, fourth electronic expansion valve 44, exhaust valve 45, drying chamber 46, intake valve 47, second fan 48, air flow baffle 49, switching valve 50, heat pump placement area 51, heating hot air duct 52, duct air outlet 53, first air outlet 54, second air outlet 55. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation manners described herein are only the best embodiments of the present invention, which are only used to explain the present invention and do not limit the protection scope of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0034] Embodiment 1

[0035] This embodiment provides a high-temperature heat pump drying system with a wide temperature range. Referring to Figure 1 , it mainly includes a heat pump heating module, a refrigerant recovery module, and a drying module. The heat pump heating module is respectively connected to the above-mentioned refrigerant recovery module and drying module, and the conversion of the heating mode of the heat pump heating module can be achieved through the refrigerant recovery module; the drying module mainly includes a waste heat heat exchanger 23 and a plurality of regulating valves. The waste heat heat exchanger 23 can communicate with the above-mentioned several regulating valves, and the switching of the drying mode of the drying module is achieved according to the movement of the wind deflector of the regulating valve.

[0036] The system of this technical solution has a low-temperature heating mode, a medium-temperature heating mode, and a high-temperature heating mode. The drying module has a closed drying mode and an open drying mode; in terms of humidity control, it is divided into high-precision humidity control and conventional humidity control modes; the low-temperature heating mode and the medium-temperature heating mode are further divided into a dual-source heating mode and a condensation heat absorption heating mode; when the return air temperature is lower than 40°C and 85°C respectively (the temperature measured by the third temperature sensor 27), the medium-temperature heating mode and the high-temperature heating mode have a fluorine pump boosting mode.

[0037] Continuing to refer to Figure 1 , the refrigerant recovery module of this technical solution includes three groups of refrigerant recovery units. Among the three groups of refrigerant recovery units, each group of refrigerant recovery units includes a gas storage tank, a vacuum pump, and an electromagnetic valve. The gas storage tank is connected to the vacuum pump, and the vacuum pump is connected to the electromagnetic valve.

[0038] In the above technical solution, the three groups of refrigerant recovery units are respectively a low-temperature refrigerant recovery unit, a medium-temperature refrigerant recovery unit, and a high-temperature refrigerant recovery unit. The refrigerant media with different operating temperatures are stored in the gas storage tanks of the three.

[0039] More specifically, the low-temperature refrigerant recovery unit includes a first gas storage tank 1, a first vacuum pump 2, and a first electromagnetic valve 3. The first gas storage tank 1 is connected to the first vacuum pump 2, and the first vacuum pump 2 is connected to the first electromagnetic valve 3.

[0040] Among them, the first gas storage tank 1 can store refrigerant media with relatively low operating temperatures, such as R134a, R410a, R32, R142b. Of course, it is not limited to only the above several media.

[0041] The medium-temperature refrigerant recovery unit includes a second gas storage tank 4, a second air extraction pump 5, and a second solenoid valve 6. The second gas storage tank 4 is connected to the second air extraction pump 5, and the second air extraction pump 5 is connected to the second solenoid valve 6.

[0042] Among them, the second gas storage tank 4 can store a refrigerant medium with a moderate operating temperature, such as R515b, but is not limited to this medium.

[0043] The high-temperature refrigerant recovery unit includes a third gas storage tank 7, a third air extraction pump 8, and a third solenoid valve 9. The third gas storage tank 7 is connected to the third air extraction pump 8, and the third air extraction pump 8 is connected to the third solenoid valve 9.

[0044] Among them, the third gas storage tank 7 can store a refrigerant medium with a high operating temperature, such as R245fa, R1233zd(E), but is not limited to the above media.

[0045] The refrigerant amounts in the first gas storage tank 1, the second gas storage tank 4, and the third gas storage tank 7 are filled according to the volume of the heat pump system.

[0046] In this embodiment, the conversion between the low-temperature heating mode, the medium-temperature heating mode, and the high-temperature heating mode is achieved through the refrigerant recovery module.

[0047] When switching from the low-temperature heating mode to the high-temperature heating mode, first start the low-temperature refrigerant recovery unit. At this time, the first solenoid valve 3 is opened, the first air extraction pump 2 is started, and the refrigerant in the heat pump system flows into the first gas storage tank 1. After the refrigerant is pumped out, the first solenoid valve 3 is closed. Then start the high-temperature refrigerant recovery unit, open the third solenoid valve 9, and the refrigerant in the third gas storage tank 7 enters the heat pump system. After filling, the third solenoid valve 9 is closed. In this way, the switching of the refrigerant in the system is completed, and the switching operations of other modes are similar.

[0048] For the heat pump heating module, it mainly includes a solar collector 13 and a first air-cooled evaporator 12. One end of the solar collector 13 is connected to the second electronic expansion valve 11, and the other end of the solar collector 13 is connected to the gas-liquid separator 32. One end of the first air-cooled evaporator 12 is connected to the first electronic expansion valve 10, and the other end of the first air-cooled evaporator 12 is also connected to the gas-liquid separator 32. In addition, the other ends of the first electronic expansion valve 10 and the second electronic expansion valve 11 are both connected to the filter 43 and the fourth electronic expansion valve 44, and the other end of the fourth electronic expansion valve 44 is connected to the refrigerant recovery module, the second air-cooled evaporator 19, and the third air-cooled evaporator 22.

[0049] In the above technical solution, in the dual-source heating mode, the low-temperature and low-pressure refrigerant enters the first air-cooled evaporator 12 and the solar collector 13 to absorb heat and become low-temperature and low-pressure superheated steam.

[0050] The first electronic expansion valve 10 and the second electronic expansion valve 11 are automatically adjusted according to the superheat of the refrigerant at the outlets of the first air-cooled evaporator 12 and the solar collector 13 (the setting range is 2 - 10 °C).

[0051] The solar collector 13 can be a PV / T module, a blown - type collector, or a flat - plate collector. The first air - cooled evaporator 12 can be a fin - tube heat exchanger or a micro - channel heat exchanger.

[0052] Furthermore, the heat pump heating module further includes a second air - cooled evaporator 19 and a third air - cooled evaporator 22. One end of the second air - cooled evaporator 19 is connected to a fourth solenoid valve 18, and the other end of the fourth solenoid valve 18 is connected to a fourth electronic expansion valve 44. One end of the third air - cooled evaporator 22 is connected to a fifth solenoid valve 21, and the other end of the fifth solenoid valve 21 is also connected to the fourth electronic expansion valve 44. The other ends of the second air - cooled evaporator 19 and the third air - cooled evaporator 22 are connected to a gas - liquid separator 32.

[0053] In the above - mentioned technical solution, the low - temperature and low - pressure refrigerant enters the second air - cooled evaporator 19 and the third air - cooled evaporator 22, absorbs heat and becomes low - pressure superheated steam.

[0054] The other ends of the fourth solenoid valve 18 and the fifth solenoid valve 21 are both connected to a fourth electronic expansion valve 44, and the opening degree of the fourth electronic expansion valve 44 is automatically adjusted according to the superheat of the refrigerant at the evaporator outlet (the setting range is 2 - 10 °C).

[0055] One end of the gas - liquid separator 32 is connected to a compressor 33, the other end of the compressor 33 is connected to an air - cooled condenser 29, the other end of the air - cooled condenser 29 is connected to a liquid storage tank 34, the other end of the liquid storage tank 34 is connected to an economizer 41, and the other end of the economizer 41 is connected to a filter 43.

[0056] In the above - mentioned technical solution, the low - temperature and low - pressure superheated refrigerant enters the compressor 33 after passing through the gas - liquid separator 32, then becomes high - temperature and high - pressure refrigerant, enters the air - cooled condenser 29 to heat the air (the air can be heated to 30 - 75 °C), cools down to become high - pressure and medium - temperature refrigerant and then enters the liquid storage tank 34, then enters the economizer 41, and then enters the filter 43.

[0057] In addition, a sixth solenoid valve 35 and a fluorine pump 36 are arranged between the liquid storage tank 34 and the economizer 41. Specifically, the above - mentioned sixth solenoid valve 35 and fluorine pump 36 are connected in parallel, and a third electronic expansion valve 42 is arranged between the economizer 41 and the filter 43. The economizer 41 is also connected to the compressor 33.

[0058] In the above technical solution, the high-pressure and medium-temperature refrigerant enters the liquid storage tank 34, then enters the economizer 41, then enters the filter 43, and is divided into two branches. One branch enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 to continue the previous process, and the other branch passes through the third electronic expansion valve 42 for throttling, and then enters the economizer 41 to be heated and evaporated. The opening of the third electronic expansion valve 42 is automatically adjusted according to the superheat of the refrigerant at the outlet of the economizer 41 (the setting range is 2~10°C), and then the refrigerant enters the compressor 33.

[0059] A first fan 28 and an electric heater 30 are also provided at both ends of the air-cooled condenser 29. Specifically, the other end of the first fan 28 is connected to the second three-way valve 26, and the other end of the electric heater 30 is connected to the drying room 46.

[0060] In the above technical solution, in the rapid start-up stage of the electric heating for high-temperature heating, the first fan 28, the second fan 48, and the electric heater 30 are turned on until the temperature of the third temperature sensor 27 reaches 85°C, and then the electric heater 30 stops working.

[0061] In addition, continue to refer to Figure 1 , a second temperature sensor 16 and a second pressure sensor 17 are provided at one end of the first air-cooled evaporator 12, a first temperature sensor 14 and a first pressure sensor 15 are provided at one end of the solar collector 13, a third temperature sensor 27 is provided at one end of the second three-way valve 26, a fourth temperature sensor 31 is provided at one end of the electric heater 30, a sixth temperature sensor 39 and a fourth pressure sensor 40 are provided between the compressor 33 and the economizer 41, and a fifth temperature sensor 37 and a third pressure sensor 38 are provided at one end of the gas-liquid separator 32.

[0062] Based on the above technical solution, in the low-temperature heating mode, the medium in the first gas storage tank 1 is specifically used as the refrigerant.

[0063] Specifically, in the condensation heat absorption and heating mode of the low-temperature heating mode, refer to Figure 1, the first electronic expansion valve 10 and the second electronic expansion valve 11 are closed, the fourth solenoid valve 18, the fifth solenoid valve 21, and the sixth solenoid valve 35 are opened. The medium-temperature and high-pressure refrigerant passes through the fourth electronic expansion valve 44, and then becomes a low-temperature and low-pressure refrigerant and enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 to absorb heat and become low-pressure superheated steam. Among them, the opening degree of the fourth electronic expansion valve 44 is automatically adjusted according to the superheat degree of the refrigerant at the evaporator outlet (the setting range is 2 to 10 °C). The low-temperature and low-pressure superheated refrigerant enters the compressor 33 after passing through the gas-liquid separator 32, and then becomes a high-temperature and high-pressure refrigerant, enters the air-cooled condenser 29 to heat the air (the air can be heated to 30 to 75 °C), cools down to become a high-pressure and medium-temperature refrigerant and enters the liquid storage tank 34, and then enters the economizer 41, and then enters the filter 43, and then is divided into two branches. One branch enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 to continue the previous process, and the other branch passes through the third electronic expansion valve 42 for throttling, and then enters the economizer 41 to be heated and evaporated. The opening degree of the third electronic expansion valve 42 is automatically adjusted according to the superheat degree of the refrigerant at the economizer 41 outlet (the setting range is 2~10 °C), and then the refrigerant enters the compressor 33.

[0064] Specifically, in the dual-source heating mode of the low-temperature heating mode, refer to Figure 1 , the fourth electronic expansion valve 44 is closed, the fourth solenoid valve 18 and the fifth solenoid valve 21 are closed, and the sixth solenoid valve 35 is opened. The medium-temperature and high-pressure refrigerant passes through the first electronic expansion valve 10 and the second electronic expansion valve 11, throttles to become a low-temperature and low-pressure refrigerant, and then enters the first air-cooled evaporator 12 and the solar collector 13 to absorb heat and become low-temperature and low-pressure superheated steam. The first electronic expansion valve 10 and the second electronic expansion valve 11 are automatically adjusted according to the superheat degree of the refrigerant at the outlets of the first air-cooled evaporator 12 and the solar collector 13 (the setting range is 2~10 °C). The low-temperature and low-pressure superheated refrigerant enters the compressor 33 after passing through the gas-liquid separator 32, and the subsequent process is the same as that of the above condensation heat absorption heating mode.

[0065] In the medium-temperature heating mode, the medium in the second storage tank 4 is used as the refrigerant. Among them, the condensation heat absorption heating mode and the dual-source heating mode are the same as these two modes of the low-temperature heating mode. The difference is that the air in the air-cooled condenser 29 can be heated to 30~100 °C. In addition, when the temperature measured by the third temperature sensor 27 is lower than 40 °C, the fluorine pump boosting mode is started. At this time, the sixth solenoid valve 35 is closed and the fluorine pump 36 is started to make up for the problem that the pressure ratio of the heat pump system is not enough due to the low condensation temperature and cannot circulate, and the rest of the process remains unchanged.

[0066] In the high-temperature heating mode, the medium in the third storage tank 7 is used as the refrigerant. The operation is divided into two stages: the start-up preheating stage and the heating operation stage. The start-up preheating stage is divided into two methods: electric heating rapid start and energy-saving start.

[0067] During the rapid start-up of electric heating, the first blower 28, the second blower 48, and the electric heater 30 are turned on until the temperature of the third temperature sensor 27 reaches 85 °C, and then the electric heater 30 stops working. Energy-saving start-up: The first blower 28 and the second blower 48 start, and the heat pump operates in the dual-source heating mode of the medium-temperature heating mode until the temperature of the third temperature sensor 27 reaches 85 °C, and then the heat pump stops operating.

[0068] During the heating operation stage, the process is basically the same as that of the condensation heat absorption heating mode in the low-temperature heating mode. The difference is that the fourth solenoid valve 18 is closed, and at this time, the refrigerant does not absorb heat through the second air-cooled evaporator 19. In addition, the air in the air-cooled condenser 29 can be heated to 50 - 200 °C. When the temperature measured by the third temperature sensor 27 is lower than 85 °C, the fluorine pump boost mode is started. At this time, the sixth solenoid valve 35 is closed and the fluorine pump 36 is started to make up for the problem that the pressure ratio of the heat pump system is not enough due to the low condensation temperature and cannot circulate, and the rest of the process remains unchanged.

[0069] Reference Figure 2 、 Figure 3 and Figure 4 According to

[0070] In the above technical solution, after the air enters the drying chamber 46 and the object to be dried absorbs heat and cools down, it passes through the second three-way valve 26. The second three-way valve 26 has a baffle that can move up and down, and its position is adjusted according to the difference between the temperature value measured by the third temperature sensor 27 and the upper limit of the allowable operating temperature of the compressor 33.

[0071] The control valve of the drying module further includes a switching valve 50, and the switching valve 50 is provided with a baffle that can move left and right.

[0072] The drying chamber 46 is respectively connected to an exhaust valve 45 and an intake valve 47, and the intake valve 47 is connected to the third temperature sensor 27.

[0073] In the above technical solution, in the open drying mode, the ambient air passes through the intake valve 47, then is sent by the first blower 28 to the air-cooled condenser 29 to be heated, then enters the heating hot air duct 52, and is sent into the drying chamber 46 through the duct air outlet 53. After the object to be dried absorbs heat and cools down, it is discharged through the exhaust valve 45.

[0074] In the closed drying mode, the exhaust valve 45 and the intake valve 47 are closed. One of the low-temperature heating mode, medium-temperature heating mode, and high-temperature heating mode is selected according to the hot air temperature required in the drying room. The condensation heat absorption heating mode needs to be selected for the low-temperature heating mode and the medium-temperature heating mode. The humidity control in the drying room is divided into a conventional humidity control mode and a high-precision humidity control mode.

[0075] For the conventional humidity control mode, refer to Figure 2 , after the air enters the drying room 46 and is cooled by absorbing heat from the object to be dried, it passes through the second three-way valve 26. The second three-way valve 26 has a baffle that can move up and down, and its position is adjusted according to the difference between the temperature value measured by the third temperature sensor 27 and the upper limit of the allowable operating temperature of the compressor 33. When the temperature difference ≤ 10 °C, the lower end of the baffle is at the lower dead point B. When the temperature difference > 10 °C, the baffle moves linearly upward until the operating temperature of the compressor 33 drops to the allowable range. The hot air then passes through the first three-way valve 25. This valve has only two modes. When in the conventional humidity control mode, the lower end of the baffle is at the lower dead point D. When in the high-precision humidity control mode, the upper end of the baffle is at the upper dead point C; the hot air then enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22, is cooled by absorbing heat, and the condensed water is discharged through the first drain pipe 20; then it passes through the switching valve 50. This valve has only two modes. When in the conventional humidity control mode, the left end of the baffle is at the left dead point D. When in the high-precision humidity control mode, the right end of the baffle is at the right dead point E; then the hot air is mixed with the air coming in from the second air inlet 55 and is sent by the first fan 28 into the air-cooled condenser 29 to be heated, then enters the hot air supply duct 52, and is sent into the drying room 46 through the duct air outlet 53.

[0076] For the high-precision humidity control mode, refer to Figure 3 : After the air enters the drying room 46 and is cooled by absorbing heat from the object to be dried, it passes through the second three-way valve 26, and then through the first three-way valve 25. The upper end of the baffle is at the upper dead point C. The hot air enters the waste heat exchanger 23, is cooled by absorbing heat and then enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 for further cooling. The condensed water is discharged through the first drain pipe 20. The right end of the baffle of the switching valve 50 is at the right dead point E. Then the hot air absorbs heat and rises in the waste heat exchanger 23. After flowing out of the waste heat exchanger 23, it is mixed with the air coming in from the second air inlet 55, and then is sent by the first fan 28 into the air-cooled condenser 29 to be heated, then enters the hot air supply duct 52, and is sent into the drying room 46 through the duct air outlet 53. The duct air outlets 53 are arranged in a progressive manner to make the distribution of hot air in the drying room 46 more uniform.

[0077] For the open drying mode, refer to Figure 4, this mode is applicable to the situation where there are relatively many air dust or impurities during the material drying process. In this mode, the dual-source heating mode of low-temperature heating mode and medium-temperature heating mode can be operated. The exhaust valve 45 and the intake valve 47 are opened, and the lower end of the baffle of the second three-way valve 26 is located at the lower dead point B. Ambient air passes through the intake valve 47, and then is sent into the air-cooled condenser 29 by the first fan 28 to be heated, and then enters the heating hot air duct 52, and is sent into the drying chamber 46 through the air duct air outlet 53. After the dried material absorbs heat and cools down, it is discharged through the exhaust valve 45. Both the compressor 33 and the first fan 28 can change the operating frequency, and the frequency change range is 20~100%. The frequency is automatically changed according to the amount of materials in the drying chamber 46 and the temperature change trend measured by the fourth temperature sensor 31 to achieve the efficient operation of the heat pump under different working conditions.

[0078] The above technical solutions can bring the following technical effects.

[0079] 1. For different material drying temperature requirements, the refrigerant medium can be automatically switched, and at the same time, the size of the heat exchanger can be flexibly switched according to the refrigerant medium, so that different refrigerants can operate efficiently in the same system, improving the availability of the equipment.

[0080] 2. For the problems of large difference in heat exchange capacity between the evaporator and the condenser and compressor operating temperature limitations (low-temperature and medium-temperature refrigerants cannot exceed 40°C, and high-temperature refrigerants cannot exceed 75°C), the air volume entering the evaporator and the condenser is flexibly adjusted through the baffle. Using the principle of large temperature difference and small flow rate, the heat exchange power can be kept unchanged, and at the same time, the compressor operating temperature can be reduced to the specified range. The condenser can also be decoupled from the air volume of the evaporator, and can achieve control at any temperature. Finally, the system can achieve the efficient and safe operation of the heat pump under the drying temperature conditions of 30~200°C.

[0081] 3. For the limitations of certain condensation temperature / condensation pressure required at the condensation end of the medium-temperature heating mode and the high-temperature heating mode (30~60°C for medium-temperature and 75~100°C for high-temperature), power is provided by adopting the method of fluorine pump pressurization, thus solving the requirement for the air temperature entering the condenser in this mode and expanding the operating temperature range of these two modes.

[0082] 4. By using the waste heat heat exchanger, the humidity of the drying system can be effectively controlled. Because the return air enters the waste heat heat exchanger and is absorbed and cooled, which is equivalent to cooling and humidifying, and then enters the evaporator to be further cooled. Compared with the conventional system, it is easier to reach the dew point temperature, and the control requirement of the lowest 15% relative humidity can be achieved.

[0083] 5. In the case of inevitably using the open drying mode, the evaporation temperature of the dual-source mode is higher than that of the air energy mode, so it is more energy-saving than the traditional open drying system.

[0084] 6. When the high-temperature heating mode is started, compared with the traditional electric heating preheating start, this embodiment adds a dual-source heating mode, which on the one hand increases the options and on the other hand improves the startup energy efficiency.

[0085] 7. The heat pump system adopts air-injection enthalpy-increasing technology, and uses the economizer to recover part of the sensible heat of the refrigerant, thereby improving the degree of subcooling. Compared with heat pumps without air-injection enthalpy-increasing technology, the COP is higher.

[0086] 8. The whole system can achieve temperature control of 30~200℃, relative humidity as low as 15%, heating power change of 20%~100%, and open or closed drying mode can be selected according to the cleanliness of the drying gas for the material. Compared with the traditional drying system, it has a wider range of applications.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A wide temperature range high temperature heat pump drying system, characterized in that: The heat pump heating module comprises a heat pump heating module, the heat pump heating module is respectively connected to a refrigerant recovery module and a drying module, and the heating mode switching of the heat pump heating module is realized by the refrigerant recovery module; the drying module comprises a waste heat exchanger (23) and a plurality of regulating valves connected to the waste heat exchanger (23), and the drying mode switching of the drying module is realized according to the movement and transformation of the windshield of the regulating valve; The refrigerant recovery module includes three groups of refrigerant recovery units. Each group of refrigerant recovery units includes a gas storage tank, an air extraction pump and a solenoid valve. The gas storage tank is connected to the air extraction pump, and the air extraction pump is connected to the solenoid valve. The three groups of refrigerant recovery units are respectively a low-temperature refrigerant recovery unit, a medium-temperature refrigerant recovery unit and a high-temperature refrigerant recovery unit. The gas storage tank of each group of refrigerant recovery units stores refrigerants with different operating temperatures.

2. A wide temperature range high temperature heat pump drying system according to claim 1, characterized in that: The heat pump heating module comprises a solar collector (13) and a first air-cooled evaporator (12), one end of the solar collector (13) is connected to a second electronic expansion valve (11), one end of the first air-cooled evaporator (12) is connected to a first electronic expansion valve (10), and the other end of the solar collector (13) and the other end of the first air-cooled evaporator (12) are both connected to a gas-liquid separator (32).

3. A wide temperature range high temperature heat pump drying system according to claim 1, characterized in that: The heat pump heating module comprises a second air-cooled evaporator (19) and a third air-cooled evaporator (22); one end of the second air-cooled evaporator (19) is connected to a fourth solenoid valve (18); one end of the third air-cooled evaporator (22) is connected to a fifth solenoid valve (21); and the other end of the second air-cooled evaporator (19) and the other end of the third air-cooled evaporator (22) are both connected to a gas-liquid separator (32).

4. A wide temperature range high temperature heat pump drying system according to claim 2, characterized in that: One end of the gas-liquid separator (32) is connected to a compressor (33), the other end of the compressor (33) is connected to an air-cooled condenser (29), the other end of the air-cooled condenser (29) is connected to a liquid storage tank (34), the other end of the liquid storage tank (34) is connected to an economizer (41), and the other end of the economizer (41) is connected to a filter (43).

5. A wide temperature range high temperature heat pump drying system according to claim 4, characterized in that: A sixth solenoid valve (35) and a fluorine pump (36) are provided between the liquid storage tank (34) and the economizer (41); the sixth solenoid valve (35) and the fluorine pump (36) are connected in parallel; a third electronic expansion valve (42) is provided between the economizer (41) and the filter (43); and the economizer (41) is also connected to the compressor (33).

6. A wide temperature range high temperature heat pump drying system according to claim 4, characterized in that: The two ends of the air-cooled condenser (29) are respectively connected to a first fan (28) and an electric heater (30), and the other end of the electric heater (30) is connected to a drying room (46).

7. A wide temperature range high temperature heat pump drying system according to claim 1, characterized in that: The regulating valve of the drying module comprises a second three-way valve (26) and a first three-way valve (25) connected to the second three-way valve (26); the second three-way valve (26) and the first three-way valve (25) are both provided with wind shields, and the wind shields can be moved and adjusted; the first three-way valve (25) is also connected to the second air-cooled evaporator (19) and the third air-cooled evaporator (22) through a waste heat exchanger (23) or directly.

8. A wide temperature range high temperature heat pump drying system according to claim 7, characterized in that: The control valve of the drying module further comprises a switching valve (50), wherein a windshield plate capable of moving leftward and rightward is arranged inside the switching valve (50).

9. A wide temperature range high temperature heat pump drying system according to claim 6, characterized in that: The drying room (46) is respectively connected to an exhaust valve (45) and an intake valve (47), and the intake valve (47) is connected to a third temperature sensor (27).

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