Multi-energy complementary combined drying system and control method thereof

Abstract

The invention relates to the technical field of drying systems, in particular to a multi-energy complementary combined drying system which comprises a solar drying system, an air source heat pump drying system, a biomass boiler drying system, an air source heat pump winter defrosting system and a control system. The solar drying system comprises a solar heat collector, a solar circulating water pump, a heat storage water tank, a drying circulating water pump and a drying box; the biomass boiler drying system comprises a biomass boiler and a biomass boiler circulating water pump; the air source heat pump drying system comprises an electric heater, an evaporator, a compressor, an expansion valve and a condenser; the air source heat pump winter defrosting system comprises a heat exchange circulating water pump and a heat exchanger, the heat exchange circulating water pump is connected with a water pump, the heat exchange circulating water pump is connected with a heat storage water tank, and the heat exchanger is connected with the heat storage water tank. And the stable operation of the drying system is kept on the basis of reducing the energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of drying systems, in particular to a multi-energy complementary combined drying system, and also to a control method for the multi-energy complementary combined drying system. Background Art

[0002] The fruit and vegetable industry is an indispensable part of the agricultural structure. However, due to the seasonality and perishability of fruit and vegetable products, improper post-processing or circulation often leads to deterioration and loss of value of fruits and vegetables. Therefore, it is necessary to take measures to improve the quality of fruit and vegetable products so that they have a longer storage time. In the food industry, drying is a widely used means of food preservation, which can remove moisture from fruits and vegetables and prevent the production and reproduction of microorganisms, thereby extending the shelf life of fruits and vegetables. At present, the main drying technologies are hot air drying, vacuum drying, and microwave drying. Hot air drying has a short time and a large processing capacity, but it has low thermal efficiency and high energy consumption during operation. Microwave drying can shorten processing time and improve efficiency, but it is easy to cause carbonization in the center of the material, which requires precise control. Vacuum drying has good versatility, but its initial investment is high. When used alone, drying technology will have its own unique advantages and disadvantages, and its general applicability is poor.

[0003] In 2020, the International Drying Association pointed out that the future development trend of drying technology is to develop in the direction of efficient use of energy, improved product quality, reduced environmental pollution, safe operation, and easy control. With the country's advocacy of energy reuse, energy conservation and emission reduction, the use of multi-heat source complementary drying has been developed.

[0004] Heat pump drying technology can save a lot of energy, achieve precise control of temperature and humidity, and ensure the quality of dried fruits and vegetables. Solar drying technology is clean and pollution-free, and has a wide range of applications. Combining solar drying with heat pumps can achieve complementary advantages and have better economic and environmental benefits. However, in winter or in cold areas, heat pumps will frost, reducing the performance of heat pumps. For solar-heat pump drying systems, solar energy alone cannot meet defrosting requirements. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in order to overcome the frosting phenomenon of heat pumps in the prior art in winter or in extremely cold areas, which reduces the performance of the heat pumps; for solar-heat pump drying systems, the defrosting requirements cannot be met by relying solely on solar energy, and a multi-energy complementary combined drying system is provided.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a multi-energy complementary combined drying system, including a solar drying system, an air source heat pump drying system, a biomass boiler drying system, an air source heat pump winter defrosting system and a control system;

[0007] The solar drying system comprises a solar collector, a solar circulating water pump, a hot water storage tank, a drying circulating water pump, and a drying box. The solar collector is connected to the solar circulating water pump, the solar circulating water pump is connected to the hot water storage tank, the solar collector is connected to the hot water storage tank, the hot water storage tank is connected to the drying circulating water pump, the drying circulating water pump is connected to the drying box, the drying box is connected to the hot water storage tank, a water vapor trap and a vacuum pump are connected in series on the drying box, the vacuum pump is used to perform vacuum treatment on the drying box, the solar collector is used to heat circulating water, and the hot water storage tank is used to store circulating water;

[0008] The biomass boiler drying system comprises a biomass boiler and a biomass boiler circulating water pump, wherein the biomass boiler is connected to a heat storage tank, the biomass boiler is connected to the biomass boiler circulating water pump, the biomass boiler circulating water pump is connected to the heat storage tank, and the biomass boiler is used to heat the circulating water;

[0009] The air source heat pump drying system comprises an electric heater, an evaporator, a compressor, an expansion valve and a condenser, wherein the air outlet end of the evaporator is connected to the air inlet end of the compressor, the air inlet end of the evaporator is connected to the air outlet end of the expansion valve, the air inlet end of the expansion valve is connected to the air outlet end of the condenser, the air inlet end of the condenser is connected to the air outlet end of the compressor, one end of the drying box is connected to the electric heater, the electric heater is connected to the ventilation fan, the ventilation fan is connected to the condenser, the other end of the drying box is connected to the exhaust fan, and the exhaust fan is connected to the evaporator;

[0010] The air source heat pump winter defrosting system comprises a heat exchange circulation water pump and a heat exchanger, wherein the heat exchange circulation water pump is connected to a water pump, the heat exchange circulation water pump is connected to a hot water storage tank, and the heat exchanger is connected to the hot water storage tank;

[0011] The control system is used to collect the process parameters of the solar drying system, air source heat pump drying system, and biomass boiler drying system, and the air source heat pump winter defrosting system, as well as to regulate the equipment in the solar drying system, air source heat pump drying system, air source heat pump winter defrosting system, and biomass boiler drying system. The present invention uses solar energy, air source heat pumps, and biomass boilers as heat sources, and electric heating as an auxiliary heat source, and adopts a parallel connection method to achieve four operating modes: solar energy-heat pump drying combined operation mode, biomass boiler-heat pump drying combined operation mode, solar energy-biomass boiler-heat pump drying combined operation mode, and hot water storage tank-heat pump drying combined operation mode; different operating modes are adopted according to different climatic conditions to maintain the smooth operation of the drying system on the basis of reducing energy consumption.

[0012] The solar drying system further comprises a valve 1 and a valve 2, wherein the valve 1 is arranged between the solar collector and the hot water storage tank, and the valve 2 is arranged between the solar circulating water pump and the hot water storage tank.

[0013] The biomass boiler drying system further includes valve three and valve four, wherein valve three is arranged between the biomass boiler and the hot water storage tank, and valve four is arranged between the biomass boiler circulating water pump and the hot water storage tank.

[0014] The air source heat pump winter defrosting system further includes valve five and valve six, wherein valve five is arranged between the heat circulation water pump and the hot water storage tank, and valve six is ​​arranged between the heat exchanger and the hot water storage tank.

[0015] It further includes an air source heat pump winter defrost system including three-way valve one and three-way valve two, wherein the three-way valve one is respectively connected to a circulating water tank, valve three and a drying circulating water pump, and the three-way valve two is respectively connected to a circulating water tank, a drying box and valve six.

[0016] Further including control systems including process parameter acquisition systems and operating equipment control systems;

[0017] The process parameter acquisition system includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a first temperature and humidity sensor, a second temperature and humidity sensor, and a third temperature and humidity sensor; the first temperature sensor, the second temperature sensor, and the third temperature sensor are respectively placed at the outlet of the solar collector, the biomass boiler, and the hot water storage tank; the first temperature and humidity sensor, the second temperature and humidity sensor, and the third temperature and humidity sensor are respectively placed between the ventilation fan and the drying box, between the ventilation fan and the drying box, and outside the drying box;

[0018] The operating equipment control system includes a controller, which reads various operating parameters in real time, and adjusts and controls the operating equipment according to the set parameters, and selects to adopt a solar energy-heat pump drying combined operation mode, a biomass boiler-heat pump drying combined operation mode, a solar energy-biomass boiler-heat pump drying combined operation mode and a hot water storage tank-heat pump drying combined operation mode.

[0019] It further includes a control method for a multi-energy complementary combined drying system, which adopts a solar energy-heat pump drying combined operation mode: if the solar energy radiation is sufficient during the day, and the temperature difference between the water temperature at the outlet of the solar collector and the water temperature at the bottom of the hot water storage tank is greater than 8°C, valves one and two are opened, the solar energy circulation water pump is started, and the water is circulated and heated in the solar energy collector-hot water storage tank; when the water temperature at the top of the hot water storage tank reaches the vacuum drying requirement, the vacuum pump is started, the drying box is vacuum treated, three-way valve one and three-way valve two are opened, the drying circulation water pump is started, hot water enters the drying box to heat the material, and the moisture is discharged through the water vapor trap to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box is further cooled and dehumidified in the evaporator after the exhaust fan releases heat and cools it, and then it is heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying box through the ventilation fan to perform hot air drying of fruits and vegetables.

[0020] Biomass boiler-heat pump drying joint operation mode: If the solar drying system stops operating on cloudy days or at night, the biomass boiler-heat pump drying joint operation mode is adopted; open valve three and valve four,

[0021] Start the circulating water pump of the biomass boiler, and the hot water generated by the biomass boiler flows to the heat storage tank; when the water temperature at the top of the heat storage tank reaches the vacuum drying requirement, start the vacuum pump, vacuum the drying box, open the three-way valve 1 and the three-way valve 2, start the drying circulating water pump, and the hot water enters the drying box to heat the material, and the water is discharged through the water vapor trap to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box is further cooled and dehumidified in the evaporator after the exhaust fan releases heat and cools it, and then it is heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying box through the ventilation fan to perform hot air drying of fruits and vegetables;

[0022] Solar energy-biomass boiler-heat pump drying joint operation mode: If the solar energy radiation is insufficient during the day, the solar energy-biomass boiler-heat pump drying joint operation mode is adopted; open valve 1, valve 2, valve 3 and valve 4, start the solar energy circulation water pump and the biomass boiler circulation water pump, and the hot water generated by the solar collector and the biomass boiler flows to the heat storage tank; when the water temperature at the top of the heat storage tank reaches the vacuum drying requirement, start the vacuum pump, vacuum the drying box, open three-way valve 1 and three-way valve 2, start the drying circulation water pump, and hot water enters the drying box to heat the material, and the water is discharged through the water vapor trap to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box is further cooled and dehumidified in the evaporator after the exhaust fan releases heat and cools it, and then it is heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying box through the ventilation fan for hot air drying of fruits and vegetables;

[0023] Heat storage tank-heat pump drying joint operation mode: If the water temperature of the upper layer of the heat storage tank can meet the drying temperature requirement, the heat storage tank-heat pump drying joint operation mode is adopted; the hot water in the heat storage tank is directly used for drying, the vacuum pump is started, the drying box is vacuum treated, the three-way valve 1 and the three-way valve 2 are opened, the drying circulation water pump is started, and the hot water enters the drying box to heat the material, and the moisture is discharged through the water vapor trap to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box is further cooled and dehumidified in the evaporator after the exhaust fan releases heat and cools it, and then it is heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying box through the ventilation fan for hot air drying of fruits and vegetables.

[0024] Defrost mode: If the temperature around the evaporator is lower than 5°C in winter or cold areas, turn on the defrost mode; open valve five, valve two, three-way valve one and three-way valve two, start the heat exchange circulation water pump, and the hot water in the heat storage tank heats the air around the evaporator through the heat exchanger under the action of the heat exchange circulation water pump, thereby preventing the heat pump from frosting and maintaining efficient operation of the system.

[0025] It further includes turning on the electric heater when the air at the condenser outlet fails to reach the specified temperature, and stopping the auxiliary heating until the temperature reaches the specified requirement.

[0026] The beneficial effects of the present invention are as follows: the present invention provides a multi-energy complementary combined drying system;

[0027] (1) The present invention uses solar energy, air source heat pump and biomass boiler as heat sources, and electric heating as an auxiliary heat source, and adopts a parallel connection mode to realize four operation modes: solar energy-heat pump drying combined operation mode, biomass boiler-heat pump drying combined operation mode, solar energy-biomass boiler-heat pump drying combined operation mode and hot water storage tank-heat pump drying combined operation mode; different operation modes are adopted according to different climatic conditions, and the stable operation of the drying system is maintained on the basis of reducing energy consumption;

[0028] (2) The present invention uses two drying technologies, hot air drying and vacuum drying, which give full play to the unique advantages of the two drying technologies and make up for the shortcomings of the two drying technologies when used alone; the new combined drying method increases the processing capacity of fruits and vegetables and further reduces the drying time;

[0029] (3) The present invention is suitable for extremely cold regions and conditions where the outdoor temperature is low in winter; the hot water storage tank can store hot water generated by solar energy and biomass boilers, and when the temperature is low, it is used to defrost the air source heat pump through a heat exchanger, so that the system maintains efficient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] In the figure: 1, solar collector, 2, solar circulating water pump, 3, biomass boiler, 4, biomass boiler circulating water pump, 5, hot water storage tank, 6, drying circulating water pump, 7, drying box, 8, water vapor trap, 9, vacuum pump, 10, heat exchange circulating water pump, 11, exhaust fan, 12, ventilation fan, 13, electric heater, 14, heat exchanger, 15, evaporator, 16, compressor, 17, expansion valve, 18, condenser, 19, valve one, 20, valve two, 21, valve three, 22, valve four, 23, valve five, 24, valve six, 25, three-way valve one, 26, three-way valve two, 27, first temperature sensor, 28, second temperature sensor, 29, third temperature sensor, 30, first temperature and humidity sensor, 31, second temperature and humidity sensor, 32, third temperature and humidity sensor, 33, controller. DETAILED DESCRIPTION

[0033] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0034] like Figure 1 It is a structural schematic diagram of the present invention, a multi-energy complementary combined drying system, including a solar drying system, an air source heat pump drying system, a biomass boiler drying system, an air source heat pump winter defrosting system and a control system;

[0035] The solar drying system comprises a solar collector 1, a solar circulating water pump 2, a hot water storage tank 5, a drying circulating water pump 6, and a drying box 7. The solar collector 1 is connected to the solar circulating water pump 2, the solar circulating water pump 2 is connected to the hot water storage tank 5, the solar collector 1 is connected to the hot water storage tank 5, the hot water storage tank 5 is connected to the drying circulating water pump 6, the drying circulating water pump 6 is connected to the drying box 7, the drying box 7 is connected to the hot water storage tank 5, a water vapor trap 8 and a vacuum pump 9 are sequentially connected in series on the drying box 7, the vacuum pump 9 is used to perform vacuum treatment on the drying box 7, the solar collector 1 is used to heat the circulating water, the hot water storage tank 5 is used to store the circulating water, and a 50 mm thick polyurethane foam board is used inside the drying box 7, and the thermal conductivity is 0.02-0.025 W / (m 2 k), with good thermal insulation and waterproof properties; the exterior is made of color steel plate; the pipes in various parts of the system are also covered with rock wool insulation materials, water vapor trap 8 model: GLEQ-711002; capacity: 750CC, vacuum pump 9 model: PCV-2MSV; pumping rate: 50L / min;

[0036] The solar drying system comprises valve one 19 and valve two 20 . Valve one 19 is arranged between the solar collector 1 and the hot water storage tank 5 , and valve two 20 is arranged between the solar circulating water pump 2 and the hot water storage tank 5 .

[0037] The two ends of the solar collector 1 are connected to the hot water storage tank 5 through the solar circulating water pump 2, valve 1 19 and valve 2 20 to form a first circulation loop, and the two ends of the hot water storage tank 5 are connected to the three-way valve 1 25, three-way valve 2 26, dry circulating water pump 6 and drying box 7 to form a second circulation loop.

[0038] The solar collector 1 is a vacuum tube type, and the area of ​​the solar collector 1 is greater than 8.5m 2 The installation angle of the solar collector 1 can be adjusted according to the local latitude, so that the water temperature in the collector can reach above 80°C in sunny summer. Furthermore, a full-glass vacuum tube solar collector is used; model: QBJ-1-145 / 2.50 / 0.25; the material is high borosilicate, and the collection area is greater than 4.5m 2 .

[0039] The biomass boiler drying system includes a biomass boiler 3 and a biomass boiler circulating water pump 4. The biomass boiler 3 is connected to a heat storage tank 5. The biomass boiler 3 is connected to the biomass boiler circulating water pump 4. The biomass boiler circulating water pump 4 is connected to the heat storage tank 5. The biomass boiler 3 is used to heat the circulating water. The thermal efficiency of the biomass boiler 3 is greater than 78%, and the temperature can be adjusted according to demand. The volume of the heat storage tank 5 is 1 ton. The inner wall of the heat storage tank 5 is made of 304 stainless steel, the outer wall of the heat storage tank is 202 stainless steel, and the insulation layer is made of 50mm polyurethane foam layer, which has good thermal insulation. The solar circulating water pump 2, the biomass boiler circulating water pump 4, the drying circulating water pump 6, and the heat exchange circulating water 10 are model: RGZB-15, power: 0.15kW, head: 20m, and the biomass boiler 3 model: PDZ-QNL-60; the fuel filler is mainly straw particles;

[0040] The biomass boiler drying system includes valve three 21 and valve four 22. The valve three 21 is arranged between the biomass boiler 3 and the hot water storage tank 5, and the valve four 22 is arranged between the biomass boiler circulating water pump 4 and the hot water storage tank 5.

[0041] The two ends of the biomass boiler 3 are connected through the biomass boiler circulating water pump 4, valve three 21 and valve four 22 to form a third circulation loop.

[0042] The air source heat pump drying system includes an electric heater 13, an evaporator 15, a compressor 16, an expansion valve 17 and a condenser 18. The outlet end of the evaporator 15 is connected to the inlet end of the compressor 16, the inlet end of the evaporator 15 is connected to the outlet end of the expansion valve 17, the inlet end of the expansion valve 17 is connected to the outlet end of the condenser 18, the inlet end of the condenser 18 is connected to the outlet end of the compressor 16, one end of the drying box 7 is connected to the electric heater 13, the electric heater 13 is connected to the ventilation fan 12, the ventilation fan 12 is connected to the condenser 18, the other end of the drying box 7 is connected to the exhaust fan 11, the exhaust fan 11 is connected to the evaporator 15, the exhaust fan 11 and the ventilation fan 12 are model: DPT10-20A; air volume: 198 / 168m 3 / h, electric heater 13 model: DN80X600; heating power: 1kW, evaporator 15 adopts plate-fin type; circulating air volume 3300kg / h, compressor 16 model: YH-5Z; power 5kW, expansion valve 17 model: TRAE+5MC, condenser 18 adopts fin-tube type, and the refrigerant used is R134a;

[0043] The two ends of the drying box 7 are connected through the exhaust fan 11, the ventilation fan 12, the electric heater 13, the evaporator 15 and the condenser 18 to form a fourth circulation loop.

[0044] The air source heat pump winter defrosting system includes a heat exchange circulation water pump 10 and a heat exchanger 14. The heat exchange circulation water pump 10 is connected to a water pump, the heat exchange circulation water pump 10 is connected to a hot water storage tank 5, the heat exchanger 14 is connected to the hot water storage tank 5, and the heat exchanger 14 is of fin-tube type; model: JN-1.

[0045] The air source heat pump winter defrosting system comprises valve five 23 and valve six 24 , wherein valve five 23 is arranged between the heat circulation water pump and the hot water storage tank 5 , and valve six 24 is arranged between the heat exchanger 14 and the hot water storage tank 5 .

[0046] The two ends of the heat exchanger 14 are connected to the heat exchange circulation water pump 2, valve five 23 and valve six 24, three-way valve one 25, three-way valve two 26 and the hot water storage tank 5 to form a fifth circulation loop. When the temperature is low in winter, the hot water storage tank 5 uses the heat stored in the solar collector 1 and the biomass boiler 3 to defrost the air source heat pump through the heat exchanger 14.

[0047] The air source heat pump winter defrosting system includes a three-way valve 1 25 and a three-way valve 2 26. The three-way valve 1 25 is respectively connected to the circulating water tank, valve 3 21 and the drying circulating water pump 6. The three-way valve 2 26 is respectively connected to the circulating water tank, the drying box 7 and valve 6 24.

[0048] The control system is used to collect process parameters of the solar drying system, air source heat pump drying system, biomass boiler drying system and the air source heat pump winter defrosting system, and is used to regulate the equipment in the solar drying system, air source heat pump drying system, air source heat pump winter defrosting system and biomass boiler drying system.

[0049] The control system includes a process parameter acquisition system and an operating equipment control system;

[0050] The process parameter acquisition system includes a first temperature sensor 27, a second temperature sensor 28, a third temperature sensor 29, a first temperature and humidity sensor 30, a second temperature and humidity sensor 31 and a third temperature and humidity sensor 32; the first temperature sensor 27, the second temperature sensor 28 and the third temperature sensor 29 are respectively placed at the outlet of the solar collector 1, the biomass boiler 3 and the hot water storage tank 5; the first temperature and humidity sensor 30, the second temperature and humidity sensor 31 and the third temperature and humidity sensor 32 are respectively placed between the ventilation fan 12 and the drying box 7, between the ventilation fan 12 and the drying box 7 and outside the drying box 7, the first temperature sensor 27, the second temperature sensor 28 and the third temperature sensor 29 are PT100 thermal resistance temperature sensors; the temperature range is 50-250°C, the first temperature and humidity sensor 30, the second temperature and humidity sensor 31 and the third temperature and humidity sensor 32 are model: DG-WDO11; the temperature range is: -40°C-80°C; the humidity range is: 0-100%RH;

[0051] The operating equipment control system includes a controller 33, which reads various operating parameters in real time, and adjusts and controls the operating equipment according to the set parameters, and selects to adopt a solar energy-heat pump drying combined operation mode, a biomass boiler-heat pump drying combined operation mode, a solar energy-biomass boiler-heat pump drying combined operation mode and a hot water storage tank-heat pump drying combined operation mode.

[0052] A control method for a multi-energy complementary combined drying system adopts a solar energy-heat pump drying combined operation mode: if the solar energy radiation is sufficient during the day, and the temperature difference between the outlet water temperature of the solar collector 1 and the bottom water temperature of the hot water storage tank 5 is greater than 8°C, valve one 19 and valve two 20 are opened, the solar energy circulation water pump 2 is started, and the water is circulated and heated in the solar energy collector 1-hot water storage tank 5; when the water temperature at the upper part of the hot water storage tank 5 reaches the vacuum drying requirement, the vacuum pump 9 is started, the drying box 7 is vacuum treated, the three-way valve one 25 and the three-way valve two 26 are opened, the drying circulation water pump 6 is started, and the hot water enters the drying box 7 to heat the material, and the water is discharged through the water vapor trap 8 to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box 7 is further cooled and dehumidified in the evaporator 15 after the exhaust fan 11 releases heat and cools it, and then it is heated by the condenser 18 to reach the temperature and humidity required by the drying process, and is sent to the drying box 7 through the ventilation fan 12 to perform hot air drying of fruits and vegetables.

[0053] Biomass boiler-heat pump drying joint operation mode: If the solar drying system stops running on cloudy days or at night, the biomass boiler 3-heat pump drying joint operation mode is adopted; open valve three 21 and valve four 22, start the biomass boiler circulating water pump 4, and the hot water generated by the biomass boiler 3 flows to the heat storage tank 5; when the water temperature at the upper part of the heat storage tank 5 reaches the vacuum drying requirement, start the vacuum pump 9, vacuum the drying box 7, open the three-way valve one 25 and the three-way valve two 26, start the drying circulating water pump 6, and the hot water enters the drying box 7 to heat the material, and the moisture is discharged through the water vapor trap 8 to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box 7 is further cooled and dehumidified in the evaporator 15 after the exhaust fan 11 releases heat and cools it, and then it is heated by the condenser 18 to reach the temperature and humidity required by the drying process, and is sent to the drying box 7 through the ventilation fan 12 for hot air drying of fruits and vegetables;

[0054] Solar energy-biomass boiler-heat pump drying joint operation mode: If the solar energy radiation is insufficient during the day, the solar energy-biomass boiler 3-heat pump drying joint operation mode is adopted; open valve 19, valve 2 20, valve 3 21 and valve 4 22, start the solar energy circulation water pump 2 and the biomass boiler circulation water pump 4, and the hot water generated by the solar collector 1 and the biomass boiler 3 flows to the heat storage tank 5; when the water temperature at the top of the heat storage tank 5 reaches the vacuum drying requirement, start the vacuum pump 9, vacuum the drying box 7, open the three-way valve 1 25 and the three-way valve 2 26, start the drying circulation water pump 6, and the hot water enters the drying box 7 to heat the material, and the water is discharged through the water vapor trap 8 to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box 7 is further cooled and dehumidified in the evaporator 15 after the exhaust fan 11 releases heat and cools it, and then it is heated by the condenser 18 to reach the temperature and humidity required by the drying process, and is sent to the drying box 7 through the ventilation fan 12 for hot air drying of fruits and vegetables;

[0055] Heat storage tank-heat pump drying joint operation mode: If the water temperature of the upper layer of the heat storage tank 5 can meet the drying temperature requirement, the heat storage tank 5-heat pump drying joint operation mode is adopted; the hot water in the heat storage tank 5 is directly used for drying, the vacuum pump 9 is started, the drying box 7 is vacuum treated, the three-way valve 1 25 and the three-way valve 2 26 are opened, the drying circulation water pump 6 is started, and the hot water enters the drying box 7 to heat the material, and the moisture is discharged through the water vapor trap 8 to complete the vacuum drying; at the same time, the hot and humid air discharged from the drying box 7 is further cooled and dehumidified in the evaporator 15 after the exhaust fan 11 releases heat and cools it, and then it is heated by the condenser 18 to reach the temperature and humidity required by the drying process, and is sent to the drying box 7 through the ventilation fan 12 for hot air drying of fruits and vegetables.

[0056] Defrost mode: If the temperature around the evaporator 15 is lower than 5°C in winter or cold areas, the defrost mode is turned on; valve five 23, valve two 20, three-way valve one 25 and three-way valve two 26 are opened, and the heat exchange circulation water pump 10 is started. The hot water in the heat storage tank 5 heats the air around the evaporator 15 through the heat exchanger 14 under the action of the heat exchange circulation water pump 10, thereby preventing the heat pump from frosting and maintaining efficient operation of the system.

[0057] When the air at the outlet of the condenser 18 fails to reach the specified temperature, the electric heater 13 is turned on until the temperature reaches the specified requirement and the auxiliary heating is stopped.

[0058] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A multi-energy complementary combined drying system, characterized in that: Including solar drying system, air source heat pump drying system, biomass boiler drying system, air source heat pump winter defrosting system and control system; The solar drying system comprises a solar collector (1), a solar circulating water pump (2), a hot water storage tank (5), a drying circulating water pump (6), and a drying box (7); the solar collector (1) is connected to the solar circulating water pump (2), the solar circulating water pump (2) is connected to the hot water storage tank (5), the solar collector (1) is connected to the hot water storage tank (5), the hot water storage tank (5) is connected to the drying circulating water pump (6), the drying circulating water pump (6) is connected to the drying box (7), the drying box (7) is connected to the hot water storage tank (5), a water vapor trap (8) and a vacuum pump (9) are sequentially connected in series on the drying box (7), the vacuum pump (9) is used to perform vacuum treatment on the drying box (7), the solar collector (1) is used to heat circulating water, and the hot water storage tank (5) is used to store circulating water; The biomass boiler drying system comprises a biomass boiler (3) and a biomass boiler circulating water pump (4); the biomass boiler (3) is connected to a heat storage tank (5); the biomass boiler (3) is connected to the biomass boiler circulating water pump (4); the biomass boiler circulating water pump (4) is connected to the heat storage tank (5); and the biomass boiler (3) is used to heat circulating water; The air source heat pump drying system comprises an electric heater (13), an evaporator (15), a compressor (16), an expansion valve (17) and a condenser (18); the air outlet end of the evaporator (15) is connected to the air inlet end of the compressor (16); the air inlet end of the evaporator (15) is connected to the air outlet end of the expansion valve (17); the air inlet end of the expansion valve (17) is connected to the air outlet end of the condenser (18); the air inlet end of the condenser (18) is connected to the air outlet end of the compressor (16); one end of the drying box (7) is connected to the electric heater (13); the electric heater (13) is connected to the ventilation fan (12); the ventilation fan (12) is connected to the condenser (18); the other end of the drying box (7) is connected to the exhaust fan (11); the exhaust fan (11) is connected to the evaporator (15); The air source heat pump winter defrosting system comprises a heat exchange circulation water pump (10) and a heat exchanger (14); the heat exchange circulation water pump (10) is connected to a water pump, the heat exchange circulation water pump (10) is connected to a heat storage tank (5), and the heat exchanger (14) is connected to the heat storage tank (5); The control system is used to collect process parameters of the solar drying system, air source heat pump drying system, biomass boiler drying system and the air source heat pump winter defrosting system, and is used to regulate the equipment in the solar drying system, air source heat pump drying system, air source heat pump winter defrosting system and biomass boiler drying system.

2. A multi-energy complementary combined drying system as claimed in claim 1, characterized in that: The solar drying system comprises valve one (19) and valve two (20), wherein valve one (19) is arranged between a solar collector (1) and a hot water storage tank (5), and valve two (20) is arranged between a solar circulating water pump (2) and a hot water storage tank (5).

3. A multi-energy complementary combined drying system as claimed in claim 1, characterized in that: The biomass boiler drying system comprises valve three (21) and valve four (22), wherein valve three (21) is arranged between the biomass boiler (3) and the hot water storage tank (5), and valve four (22) is arranged between the biomass boiler circulating water pump (4) and the hot water storage tank (5).

4. The multi-energy complementary combined drying system according to claim 1, characterized in that: The air source heat pump winter defrosting system comprises valve five (23) and valve six (24), wherein valve five (23) is arranged between the heat circulation water pump and the hot water storage tank (5), and valve six (24) is arranged between the heat exchanger (14) and the hot water storage tank (5).

5. The multi-energy complementary combined drying system according to claim 1, characterized in that: The air source heat pump winter defrosting system comprises a three-way valve one (25) and a three-way valve two (26), wherein the three-way valve one (25) is respectively connected to a circulating water tank, a valve three (21) and a drying circulating water pump (6), and the three-way valve two (26) is respectively connected to a circulating water tank, a drying box (7) and a valve six (24).

6. The multi-energy complementary combined drying system according to claim 1, characterized in that: The control system includes a process parameter acquisition system and an operating equipment control system; The process parameter acquisition system comprises a first temperature sensor (27), a second temperature sensor (28), a third temperature sensor (29), a first temperature and humidity sensor (30), a second temperature and humidity sensor (31) and a third temperature and humidity sensor (32); the first temperature sensor (27), the second temperature sensor (28) and the third temperature sensor (29) are respectively placed at the outlets of the solar collector (1), the biomass boiler (3) and the hot water storage tank (5); the first temperature and humidity sensor (30), the second temperature and humidity sensor (31) and the third temperature and humidity sensor (32) are respectively placed between the ventilation fan (12) and the drying box (7), between the ventilation fan (12) and the drying box (7) and outside the drying box (7); The operating equipment control system comprises a controller (33), wherein the controller (33) reads various operating parameters in real time, and according to the set parameters, regulates and controls the operating equipment according to the settings, and selects to adopt a solar energy-heat pump drying combined operation mode, a biomass boiler-heat pump drying combined operation mode, a solar energy-biomass boiler-heat pump drying combined operation mode, and a hot water storage tank-heat pump drying combined operation mode.

7. A control method for the multi-energy complementary combined drying system according to claim 1, characterized in that: A solar energy-heat pump drying combined operation mode is adopted: if the solar energy radiation is sufficient during the day, and the temperature difference between the outlet water temperature of the solar collector (1) and the bottom water temperature of the hot water storage tank (5) is greater than 8°C, valve 1 (19) and valve 2 (20) are opened, the solar energy circulation water pump (2) is started, and the water is circulated and heated in the solar energy collector (1)-hot water storage tank (5); when the water temperature at the top of the hot water storage tank (5) reaches the vacuum drying requirement, the vacuum pump (9) is started, the drying box (7) is vacuumized, and the three-way valve is opened. Valve 1 (25) and three-way valve 2 (26) are opened to start the drying circulation water pump (6), and hot water enters the drying box (7) to heat the material, and the water is discharged through the water vapor trap (8), thereby completing vacuum drying; at the same time, the hot and humid air discharged from the drying box (7) is further cooled and dehumidified in the evaporator (15) after being cooled by the exhaust fan (11) and then heated by the condenser (18) to reach the temperature and humidity required by the drying process, and then sent to the drying box (7) through the ventilation fan (12) to perform hot air drying on the fruits and vegetables; Biomass boiler-heat pump drying combined operation mode: If the solar drying system stops operating on cloudy days or at night, the biomass boiler-heat pump drying combined operation mode is adopted; open valve three (21) and valve four (22), The biomass boiler circulating water pump (4) is started, and the hot water generated by the biomass boiler (3) flows to the heat storage tank (5); when the water temperature at the upper part of the heat storage tank (5) reaches the vacuum drying requirement, the vacuum pump (9) is started, the drying box (7) is vacuum treated, the three-way valve 1 (25) and the three-way valve 2 (26) are opened, the drying circulating water pump (6) is started, and the hot water enters the drying box (7) to heat the material, and the water is discharged through the water vapor trap (8), and the vacuum drying is completed; at the same time, the hot and humid air discharged from the drying box (7) is further cooled and dehumidified in the evaporator (15) after the exhaust fan (11) releases heat and cools the air, and then the hot and humid air is heated by the condenser (18) to reach the temperature and humidity required by the drying process, and then the hot and humid air is sent to the drying box (7) through the ventilation fan (12) to perform hot air drying on the fruits and vegetables; Solar energy-biomass boiler-heat pump drying combined operation mode: If the solar radiation is insufficient during the day, the solar energy-biomass boiler (3)-heat pump drying combined operation mode is adopted; valve one (19), valve two (20), valve three (21) and valve four (22) are opened, the solar energy circulation water pump (2) and the biomass boiler circulation water pump (4) are started, and the hot water generated by the solar collector (1) and the biomass boiler (3) flows to the hot water storage tank (5); when the water temperature at the top of the hot water storage tank (5) reaches the vacuum drying requirement, the vacuum pump (9) is started to The drying box (7) is subjected to vacuum treatment, the three-way valve 1 (25) and the three-way valve 2 (26) are opened, the drying circulation water pump (6) is started, hot water enters the drying box (7) to heat the material, and the water is discharged through the water vapor trap (8), thereby completing vacuum drying; at the same time, the hot and humid air discharged from the drying box (7) is further cooled and dehumidified in the evaporator (15) after the exhaust fan (11) releases heat and cools the hot and humid air, and then is heated by the condenser (18) to reach the temperature and humidity required by the drying process, and is then sent to the drying box (7) through the ventilation fan (12) to perform hot air drying on the fruits and vegetables; Heat storage tank-heat pump drying combined operation mode: If the water temperature of the upper layer of the heat storage tank (5) can meet the drying temperature requirement, the heat storage tank (5)-heat pump drying combined operation mode is adopted; the hot water in the heat storage tank (5) is directly used for drying, the vacuum pump (9) is started, the drying box (7) is vacuumized, the three-way valve 1 (25) and the three-way valve 2 (26) are opened, the drying circulation water pump (6) is started, the hot water enters the drying box (7) to heat the material, and the water is discharged through the water vapor trap (8), and the vacuum drying is completed; at the same time, the hot and humid air discharged from the drying box (7) is further cooled and dehumidified in the evaporator (15) after the exhaust fan (11) releases heat and cools it, and then it is heated by the condenser (18) to reach the temperature and humidity required by the drying process, and is sent to the drying box (7) through the ventilation fan (12) to perform hot air drying on fruits and vegetables; Defrost mode: If the temperature around the evaporator (15) is lower than 5°C in winter or in cold areas, the defrost mode is turned on; valve five (23), valve two (20), three-way valve one (25) and three-way valve two (26) are opened, and the heat exchange circulation water pump (10) is started. The hot water in the heat storage tank (5) is heated by the heat exchanger (14) to heat the air around the evaporator (15) under the action of the heat exchange circulation water pump (10), thereby preventing the heat pump from frosting and maintaining the efficient operation of the system.

8. The control method of the multi-energy complementary combined drying system according to claim 7 is characterized in that: When the air at the outlet of the condenser (18) fails to reach the specified temperature, the electric heater (13) is turned on until the temperature reaches the specified requirement and the auxiliary heating is stopped.

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