Wide-temperature-zone high-temperature heat pump drying system

Abstract

The invention discloses a wide-temperature-range high-temperature heat pump drying system, relates to the field of heating and drying, and aims to solve the problem that the equipment utilization rate is low due to the fact that the running temperature of an existing drying system is greatly limited. The system comprises a heat pump heating module, and the heat pump heating module is connected with a refrigerant recycling 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 comprises a waste heat exchanger and a plurality of regulating valves communicated with the waste heat exchanger, and the drying mode switching of the drying module is realized according to the movement and transformation of wind shields of the regulating valves. According to the wide-temperature-zone high-temperature heat pump drying system, efficient and safe operation of the heat pump at the drying temperature of 30-200 DEG C can be achieved, the availability of equipment is improved, and the application range is wider.

Description

Technical Field

[0001] The invention relates to the field of heating and drying, and in particular 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 problems of high energy consumption and high operating costs, and do not meet the dual-carbon development goals of energy. Drying systems based on heat pump technology are relatively mature, but are generally used in scenarios with lower 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 condensing temperature failing 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 condensing pressure. In addition, the operating temperature of the existing drying system has great limitations, resulting in low equipment utilization and reduced economic efficiency.

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

[0004] The present invention solves the problem that the operating temperature of the existing drying system has great limitations, which will cause low equipment utilization rate. A high-temperature heat pump drying system with a wide temperature range is proposed, which can realize efficient and safe operation of the heat pump under the drying temperature conditions of 30-200°C, improve the utilization rate of the equipment, and has a wider range of applications.

[0005] In order to achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a wide temperature range high-temperature heat pump drying system, comprising a heat pump heating module, wherein the heat pump heating module 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 comprises a waste heat exchanger and a plurality of control valves connected to the waste heat exchanger, and the drying mode switching of the drying module is realized according to the movement and transformation of the wind shield of the control valve.

[0006] The 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 30~200℃ in temperature control, the lowest relative humidity can be 15%, and the heating power change can be 20%~100%. According to the cleanliness of the material drying gas, an open or closed drying mode can be selected. Compared with the traditional drying system, it has a wider range of applications.

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

[0008] In this 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, and the gas storage tanks in the three units store refrigerants with different operating temperatures.

[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, one end of the first air-cooled evaporator is connected to a first electronic expansion valve, and the other end of the solar collector and the other end of 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 become 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, one end of the third air-cooled evaporator is connected to a fifth solenoid valve, and the other end of the second air-cooled evaporator and the other end of 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 become 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, and then becomes a high-temperature and high-pressure refrigerant, enters the air-cooled condenser to heat the air (the air can be heated to 30~75℃), cools down to become a high-pressure and medium-temperature refrigerant, 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 connected 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, and 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 is throttled by the third electronic expansion valve, and then enters the economizer to be heated and evaporated. The opening of the third electronic expansion valve is automatically adjusted according to the superheat of the refrigerant at the economizer outlet (the setting range is 2~10℃), and then the refrigerant enters the compressor.

[0017] The present invention is further configured such that: both ends of the air-cooled condenser are respectively connected to a first fan and an electric heater, and the other end of the electric heater is connected to a drying room.

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

[0019] The present invention is further configured as follows: the regulating valve of the drying module includes a second three-way valve and a first three-way valve connected to the second three-way valve, and the second three-way valve and the first three-way valve are both provided with wind shields, and the wind shields can be moved and adjusted; 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 room and absorbs heat and cools down by the dried object, it passes through the second three-way valve. The second three-way valve has a wind shield 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 and the upper limit of the allowable operating temperature of the compressor.

[0021] The present invention is further configured as follows: the regulating valve of the drying module also includes a switching valve, and a windshield plate that can move left and right is provided inside the switching valve.

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

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

[0024] In this technical solution, in the open drying mode, the ambient air passes through the air inlet valve, is then sent into the air-cooled condenser by the first fan to be heated, then enters the heating hot air duct, is sent into the drying room through the duct outlet, and is discharged through the exhaust valve after being absorbed by the dried material and cooled.

[0025] The present invention can bring the following beneficial effects: The invention relates to a wide temperature range high temperature heat pump drying system, which can realize efficient and safe operation of the heat pump under the drying temperature condition of 30-200°C, improve the availability of the equipment, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an overall schematic diagram of a wide temperature range high temperature heat pump drying system of the present application.

[0027] Figure 2 It is a schematic diagram of the air flow direction in the conventional humidity control mode of the closed drying mode of the present application.

[0028] Figure 3 It is a schematic diagram of the air flow direction in the highly humidity controlled mode of the closed drying mode of the present application.

[0029] Figure 4 It is a schematic diagram of the air flow direction in the open drying mode of this application.

[0030] Reference numerals: The first gas storage tank 1, the first air pump 2, the first solenoid valve 3, the second gas storage tank 4, the second air pump 5, the second solenoid valve 6, the third gas storage tank 7, the third air pump 8, the third solenoid valve 9, the first electronic expansion valve 10, the second electronic expansion valve 11, the first air-cooled evaporator 12, the solar collector 13, the first temperature sensor 14, the first pressure sensor 15, the second temperature sensor 16, the second pressure sensor 17, the fourth solenoid valve 18, the second air-cooled evaporator 19, the first drain pipe 20, the fifth solenoid valve 21, the third air-cooled evaporator 22, the waste heat exchanger 23, the second drain pipe 24, the first three-way valve 25, the second three-way valve 26, the 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 room 46, air 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

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1 This embodiment provides a wide temperature range high temperature heat pump drying system. Figure 1 , 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 the drying module. The heating mode conversion of the heat pump heating module can be realized through the refrigerant recovery module; the drying module mainly includes a waste heat exchanger 23 and multiple control valves. The waste heat exchanger 23 can be connected to the above-mentioned multiple control valves. The drying mode switching of the drying module is realized according to the movement and transformation of the windshield of the control valve.

[0033] The system of the present technical solution has a low-temperature heating mode, a medium-temperature heating mode, and a high-temperature heating mode, and the drying module has a closed drying mode and an open drying mode; in terms of humidity control, it is divided into a high humidity control mode and a conventional humidity control mode; 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 boost mode.

[0034] Continue to refer Figure 1 The refrigerant recovery module of the present technical solution includes three groups of refrigerant recovery units. Among the three groups of refrigerant recovery units, each group of refrigerant recovery units includes an air storage tank, an air extraction pump and an electromagnetic valve. The air storage tank is connected to the air extraction pump, and the air extraction pump is connected to the electromagnetic valve.

[0035] 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, and the gas storage tanks in the three units store refrigerants with different operating temperatures.

[0036] In more detail, the low-temperature refrigerant recovery unit includes a first gas storage tank 1, a first air pump 2 and a first solenoid valve 3, the first gas storage tank 1 is connected to the first air pump 2, and the first air pump 2 is connected to the first solenoid valve 3.

[0037] The first gas storage tank 1 can store refrigerant with a relatively low operating temperature, such as R134a, R410a, R32, and R142b, but is certainly not limited to the above-mentioned refrigerant.

[0038] 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 .

[0039] The second gas storage tank 4 can store a refrigerant medium with a moderate operating temperature, such as R515b, but is certainly not limited to this medium.

[0040] The high-temperature refrigerant recovery unit includes a third gas storage tank 7 , a third air pump 8 and a third solenoid valve 9 . The third gas storage tank 7 is connected to the third air pump 8 , and the third air pump 8 is connected to the third solenoid valve 9 .

[0041] The third gas storage tank 7 can store refrigerant with a relatively high operating temperature, such as R245fa, R1233zd(E), but is certainly not limited to the above-mentioned medium.

[0042] The amount of refrigerant in the first gas storage tank 1, the second gas storage tank 4, and the third gas storage tank 7 is filled according to the volume of the heat pump system.

[0043] In this embodiment, the conversion among the low-temperature heating mode, the medium-temperature heating mode and the high-temperature heating mode is realized through the refrigerant recovery module.

[0044] When switching from low-temperature heating mode to high-temperature heating mode, first start the low-temperature refrigerant recovery unit. At this time, the first solenoid valve 3 is opened, the first vacuum pump 2 is started, and the refrigerant in the heat pump system flows into the first gas tank 1. After the refrigerant is exhausted, the first solenoid valve 3 is closed, and then the high-temperature refrigerant recovery unit is started, and the third solenoid valve 9 is opened. The refrigerant in the third gas tank 7 enters the heat pump system. After charging, the third solenoid valve 9 is closed. In this way, the switching of the refrigerant in the system is completed. The switching operations of other modes are similar.

[0045] 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 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.

[0046] 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.

[0047] 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).

[0048] The solar collector 13 may be a PV / T assembly, an inflation collector, or a flat plate collector. The first air-cooled evaporator 12 may be a fin-and-tube heat exchanger or a microchannel heat exchanger.

[0049] Furthermore, the heat pump heating module also 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 the fourth solenoid valve 18, the other end of the fourth solenoid valve 18 is connected to the fourth electronic expansion valve 44, one end of the third air-cooled evaporator 22 is connected to the fifth solenoid valve 21, the other end of the fifth solenoid valve 21 is also connected to the fourth electronic expansion valve 44, the other end of the second air-cooled evaporator 19 and the other end of the third air-cooled evaporator 22 are connected to the gas-liquid separator 32.

[0050] In the above technical solution, the low-temperature and low-pressure refrigerant enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 to absorb heat and become low-pressure superheated steam.

[0051] 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 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).

[0052] One end of the gas-liquid separator 32 is connected to the compressor 33 , the other end of the compressor 33 is connected to the air-cooled condenser 29 , the other end of the air-cooled condenser 29 is connected to the liquid storage tank 34 , the other end of the liquid storage tank 34 is connected to the economizer 41 , and the other end of the economizer 41 is connected to the filter 43 .

[0053] In the above technical solution, the low-temperature and low-pressure superheated refrigerant passes through the gas-liquid separator 32 and enters the compressor 33, 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 30~75℃), cools down to become a high-pressure and medium-temperature refrigerant, and then enters the liquid storage tank 34, and then enters the economizer 41, and then enters the filter 43.

[0054] In addition, a sixth solenoid valve 35 and a fluorine pump 36 are provided between the liquid storage tank 34 and the economizer 41. Specifically, the sixth solenoid valve 35 and the fluorine pump 36 are connected in parallel with each other, and a third electronic expansion valve 42 is provided between the economizer 41 and the filter 43. The economizer 41 is also connected to the compressor 33.

[0055] In the above technical solution, the high-pressure and medium-temperature refrigerant enters the liquid storage tank 34, then enters the economizer 41, and 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 is throttled by the third electronic expansion valve 42, 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℃), and then the refrigerant enters the compressor 33.

[0056] 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 chamber 46 .

[0057] In the above technical solution, during the electric heating quick start stage of 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.

[0058] 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.

[0059] Based on the above technical solution, in the low-temperature heating mode, the refrigerant specifically used is the medium in the first gas storage tank 1 .

[0060] Specifically, in the condensing heat absorption 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, and 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 of the refrigerant at the evaporator outlet (the setting range is 2 to 10°C). The low-temperature and low-pressure superheated refrigerant passes through the gas-liquid separator 32 and enters the compressor 33, 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, 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 of which enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22 to continue the previous process, and the other is throttled by the third electronic expansion valve 42, and then enters the economizer 41 for double heating and evaporation. 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.

[0061] 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, throttling 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 a 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 of the refrigerant at the outlet of the first air-cooled evaporator 12 and the solar collector 13 (the setting range is 2~10℃). The low-temperature and low-pressure superheated refrigerant passes through the gas-liquid separator 32 and enters the compressor 33, and the subsequent process is consistent with the above-mentioned condensation heat absorption heating mode.

[0062] In the medium-temperature heating mode, the refrigerant is the medium in the second gas storage tank 4, wherein the condensation heat absorption heating mode, the dual-source heating mode and the low-temperature heating mode are the same, except 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 which time the sixth solenoid valve 35 is closed and the fluorine pump 36 is started, and the fluorine pump boosting compensates for the problem that the heat pump system cannot circulate due to insufficient pressure ratio caused by the low condensing temperature, and the rest of the process remains unchanged.

[0063] In the high temperature heating mode, the refrigerant uses the medium in the third gas storage tank 7. 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 modes: electric heating quick start and energy-saving start.

[0064] During the electric heating quick start, 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. Energy-saving start: The first fan 28 and the second fan 48 start, and the heat pump runs 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 running.

[0065] In the heating operation stage, the process is basically the same as the condensation heat absorption heating mode of the low-temperature heating mode, except that the fourth solenoid valve 18 is closed, and the refrigerant does not pass through the second air-cooled evaporator 19 to absorb heat. 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 boosting mode is started. At this time, the sixth solenoid valve 35 is closed and the fluorine pump 36 is started. The fluorine pump boosting compensates for the problem that the heat pump system cannot circulate due to insufficient pressure ratio caused by the low condensing temperature, and the rest of the process remains unchanged.

[0066] refer to Figure 2 , Figure 3 and Figure 4 The technical solution also includes a drying module. The regulating valve of the drying module mainly includes a second three-way valve 26 and a first three-way valve 25. The first three-way valve 25 is connected to the second three-way valve 26. Both the second three-way valve 26 and the first three-way valve 25 are provided with wind shields, which 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 the waste heat exchanger 23 or directly.

[0067] In the above technical solution, after the air enters the drying room 46 and is cooled by the dried object after absorbing heat, it passes through the second three-way valve 26. The second three-way valve 26 has a wind shield 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 operating temperature allowed by the compressor 33.

[0068] The regulating valve of the drying module further includes a switching valve 50 , in which a windshield plate capable of moving left and right is provided.

[0069] The drying room 46 is connected to the exhaust valve 45 and the intake valve 47 respectively, and the intake valve 47 is connected to the third temperature sensor 27 .

[0070] In the above technical solution, in the open drying mode, the ambient air passes through the air inlet valve 47, and is then 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 room 46 through the duct outlet 53, and is discharged through the exhaust valve 45 after being absorbed by the dried material and cooled.

[0071] In the closed drying mode, the exhaust valve 45 and the air inlet valve 47 are closed. According to the required heating air temperature of the drying room, one of the low temperature heating mode, the medium temperature heating mode and the high temperature heating mode is selected. The low temperature heating mode and the medium temperature heating mode need to select the condensation heat absorption heating mode. The humidity control of the drying room is divided into the conventional humidity control mode and the high humidity control mode.

[0072] For conventional humidity control mode, refer to Figure 2 After the air enters the drying room 46 and is cooled by the dried material after absorbing heat, it passes through the second three-way valve 26. The second three-way valve 26 has a windshield that can move up and down. 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 is ≤10°C, the lower end of the windshield is located at the lower dead point B. When the temperature difference is greater than 10°C, the windshield moves linearly upward until the operating temperature of the compressor 33 drops to an allowable range. The hot air then passes through the first three-way valve 25, which has only two modes. When in the conventional humidity control mode, the lower end of the wind shield is located at the lower dead point D, and when in the high humidity control mode, the upper end of the wind shield is located at the upper dead point C; the hot air then enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22, where it is cooled after absorbing heat, and the condensed water is discharged through the first drain pipe 20; then it passes through the switching valve 50, which has only two modes. When in the conventional humidity control mode, the left end of the wind shield is located at the left dead point D, and when in the high humidity control mode, the right end of the wind shield is located at the right dead point E; then the hot air is mixed with the air coming in from the second air outlet 55 and is sent to 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 to the drying room 46 by the air duct outlet 53.

[0073] For high humidity control mode, refer to Figure 3 : After the air enters the drying room 46 and is cooled by the dried object, it passes through the second three-way valve 26, and then passes through the first three-way valve 25. The upper end of the windshield is located at the upper dead point C. The hot air enters the waste heat exchanger 23, and after being cooled by the heat, it enters the second air-cooled evaporator 19 and the third air-cooled evaporator 22, and is further cooled. The condensed water is discharged through the first drain pipe 20. The right end of the windshield of the switching valve 50 is located at the right dead point E. Then the hot air enters the waste heat exchanger 23 and absorbs heat and heats up. After flowing out of the waste heat exchanger 23, it mixes with the air coming in from the second air outlet 55, and then is sent to 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 to the drying room 46 by the duct air outlet 53. The duct air outlet 53 is arranged in a progressive manner to make the hot air more evenly distributed in the drying room 46.

[0074] For open drying mode, refer to Figure 4This mode is designed for situations where there is a lot of dust or impurities in the air 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 air inlet valve 47 are opened, and the lower end of the wind shield of the second three-way valve 26 is located at the lower dead point B. The ambient air passes through the air inlet valve 47, and is then sent to 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 to the drying room 46 by the duct vent 53. The dried material absorbs heat and cools down before being discharged through the exhaust valve 45. The compressor 33 and the first fan 28 can both change the operating frequency, and the frequency variation range is 20~100%. The frequency is automatically changed according to the amount of material in the drying room 46 and the temperature change trend measured by the fourth temperature sensor 31, so as to achieve efficient operation of the heat pump under different working conditions.

[0075] The above technical solution can bring the following technical effects.

[0076] 1. According to different material drying temperature requirements, the refrigerant medium can be automatically switched, and the size of the heater can be flexibly switched according to the refrigerant medium, so that different refrigerants can operate efficiently in the same system and improve the availability of equipment.

[0077] 2. In order to solve the problems of large difference in heat exchange between evaporator and condenser and temperature limit of compressor (low-temperature and medium-temperature refrigerant cannot exceed 40℃, and high-temperature refrigerant cannot exceed 75℃), the air volume entering the evaporator and condenser can be flexibly adjusted through the wind shield. The principle of large temperature difference and small flow rate can be used to achieve constant heat exchange power and reduce the compressor operating temperature to the specified range. The condenser can also be decoupled from the evaporator air volume to achieve arbitrary temperature control. Finally, this system can achieve efficient and safe operation of the heat pump under drying temperature conditions of 30~200℃.

[0078] 3. In view of the restrictions on the condensing temperature / condensing pressure required at the condensing end of the medium-temperature heating mode and the high-temperature heating mode (the medium temperature requires 30~60℃, and the high temperature requires 75~100℃), the fluorine pump boosting method is used to provide power, thereby solving the requirements of this mode on the air temperature entering the condenser and expanding the operating temperature range of these two modes.

[0079] 4. By utilizing the waste heat exchanger, the humidity of the drying system can be effectively controlled, because the return air enters the waste heat exchanger and absorbs heat to cool it down, which is equivalent to cooling and humidifying, and then enters the evaporator to be further cooled. Compared with conventional systems, it is easier to reach the dew point temperature and can achieve the minimum control requirement of 15% relative humidity.

[0080] 5. When the open drying mode is unavoidable, the dual-source mode has a higher evaporation temperature than the air energy mode, so it is more energy-efficient than the traditional open drying system.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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: It 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 through 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.

2. A wide temperature range high temperature heat pump drying system according to claim 1, characterized in that: The refrigerant recovery module includes three groups of refrigerant recovery units, and each group of refrigerant recovery units includes a gas storage tank and an air extraction pump and a solenoid valve connected to the gas storage tank in sequence.

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

4. A wide temperature range high temperature heat pump drying system according to claim 1 or 2, 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).

5. A wide temperature range high temperature heat pump drying system according to claim 3, 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).

6. A wide temperature range high temperature heat pump drying system according to claim 5, 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).

7. A wide temperature range high temperature heat pump drying system according to claim 5, 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).

8. The 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 are movable and adjustable; the first three-way valve (25) is also connected to the second air-cooled evaporator (19) and the third air-cooled evaporator (22) via a waste heat exchanger (23) or directly.

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

10. A wide temperature range high temperature heat pump drying system according to claim 7, 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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