A multi-energy complementary combined drying system and control method thereof

Abstract

The present invention relates to the technical field of drying systems, and in particular to a multi-energy complementary combined drying system, comprising 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 collector, a solar circulating water pump, a heat storage 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 to a water pump, the heat exchange circulating water pump is connected to a heat storage tank, and the heat exchanger is connected to the heat storage tank. The present invention adopts different operating modes according to different climatic conditions, and maintains the stable operation of the drying system on the basis of reducing 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 integral part of the agricultural landscape. However, due to the seasonality and perishability of fruit and vegetable products, improper post-processing or distribution often leads to spoilage, resulting in a loss of value. Therefore, methods are needed to improve the quality of fruit and vegetable products and extend their shelf life. Drying is a widely used food preservation method in the food industry, removing moisture from fruits and vegetables and preventing the growth of microorganisms, thereby extending their shelf life. Currently, the main drying technologies include hot air drying, vacuum drying, and microwave drying. Hot air drying offers a short processing time and high throughput, but suffers from low thermal efficiency and high energy consumption. Microwave drying can shorten processing time and improve efficiency, but it can easily cause charring in the center of the material, requiring precise control. Vacuum drying offers great versatility, but the initial investment is relatively high. Each drying technology has its own unique advantages and disadvantages when used individually, making it less universally applicable.

[0003] In 2020, the International Drying Association stated that the future development trend of drying technology is towards efficient energy utilization, 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 multiple heat sources for complementary drying has gained momentum.

[0004] Heat pump drying technology can save significant energy, achieve precise control of temperature and humidity, and ensure the quality of dried fruits and vegetables. Solar drying technology is clean, pollution-free, and has a wide range of applications. Combining solar drying with heat pumps can complement each other's strengths and achieve better economic and environmental benefits. However, in winter or in extremely cold regions, heat pumps can frost, reducing their performance. For solar-heat pump drying systems, relying solely on solar energy is insufficient for defrosting. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in order to overcome the problem in the prior art that frost may occur in heat pumps in winter or in extremely cold areas, thereby reducing the performance of the heat pump; 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 includes a solar collector, a solar circulating water pump, a heat 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 heat storage tank, the solar collector is connected to the heat storage tank, the heat storage tank is connected to the drying circulating water pump, the drying circulating water pump is connected to the drying box, and the drying box is connected to the heat storage tank. A water vapor trap and a vacuum pump are sequentially connected in series to 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. The heat storage tank is used to store circulating water.

[0008] The biomass boiler drying system includes a biomass boiler and a biomass boiler circulating water pump. 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. The biomass boiler is used to heat the circulating water.

[0009] The air source heat pump drying system includes an electric heater, an evaporator, a compressor, an expansion valve and a condenser, 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 includes a heat exchange circulation water pump and a heat exchanger, wherein the heat exchange circulation water pump is connected to the water pump, the heat exchange circulation water pump is connected to the heat storage tank, and the heat exchanger is connected to the heat 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 pump, and biomass boiler as heat sources, and electric heating as an auxiliary heat source, and adopts a parallel connection method to realize 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, and the stable operation of the drying system is maintained on the basis of reducing energy consumption.

[0012] The solar drying system further includes 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] It further includes an air source heat pump winter defrosting system including 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 defrosting system including three-way valve one and three-way valve two, wherein the three-way valve one is respectively connected to the circulating water tank, valve three and the drying circulating water pump, and the three-way valve two is respectively connected to the circulating water tank, the drying box and valve six.

[0016] Further including a control system including a process parameter acquisition system and an operating equipment control system;

[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] The invention 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 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 upper part of the hot water storage tank reaches the vacuum drying requirement, the vacuum pump is started, the drying box is vacuum-treated, three-way valves one and 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 cooled by the exhaust fan after dissipating heat, and is further cooled and dehumidified in the evaporator, and then heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying box by the ventilation fan for hot air drying of fruits and vegetables.

[0020] 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 valves three and four,

[0021] Start the biomass boiler circulating water pump, 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 to vacuum the drying box, open three-way valve 1 and three-way valve 2, start the drying circulating water pump, and hot water enters the drying box to heat the material. The moisture is discharged through the water vapor trap, completing the vacuum drying; at the same time, the hot and humid air discharged from the drying box is cooled by the exhaust fan and further cooled and dehumidified in the evaporator. It is then 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.

[0022] Solar energy-biomass boiler-heat pump drying combined operation mode: If solar radiation is insufficient during the day, the solar energy-biomass boiler-heat pump drying combined operation mode is adopted; valves 1, 2, 3 and 4 are opened to 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, the vacuum pump is started to vacuum the drying oven, three-way valves 1 and 2 are opened, the drying circulation water pump is started, and hot water enters the drying oven 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 oven is cooled by the exhaust fan after dissipation of heat, and is further cooled and dehumidified in the evaporator, and then heated by the condenser to reach the temperature and humidity required by the drying process, and is sent to the drying oven through the ventilation fan for hot air drying of fruits and vegetables;

[0023] Heat storage tank - heat pump drying combined operation mode: If the water temperature in the upper layer of the heat storage tank can meet the drying temperature requirements, the heat storage tank - heat pump drying combined 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 cooled by the exhaust fan after heat release, and is further cooled and dehumidified in the evaporator, and then 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, the defrost mode is turned on; valve five, valve two, three-way valve one and three-way valve two are opened, and the heat exchange circulation water pump is started. The hot water in the heat storage tank is heated by the heat exchange circulation water pump to heat the air around the evaporator through the heat exchanger, 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 auxiliary heat source, and adopts a parallel connection mode to realize 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, thereby maintaining the stable operation of the drying system on the basis of reducing energy consumption;

[0028] (2) The present invention uses 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 areas 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 the heat exchanger, so that the system maintains efficient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[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, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner, and thus only show components related to the present invention.

[0034] like Figure 1 This is a schematic diagram of the structure 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 includes 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 the interior of the drying box 7 uses a 50mm thick polyurethane foam board with a thermal conductivity of 0.02-0.025W / (m 2 k), with good thermal insulation and waterproof properties; the exterior is made of color-coated steel plates; all pipes in 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 includes valve 1 19 and valve 2 20 . Valve 1 19 is arranged between the solar collector 1 and the hot water storage tank 5 , and valve 2 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, drying circulating water pump 6 and drying box 7 to form a second circulation loop.

[0038] The solar collector 1 adopts 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℃ 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 capacity 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 with 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 is: PDZ-QNL-60; the fuel filler is mainly straw particles;

[0040] The biomass boiler drying system includes valve three 21 and valve four 22. 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.

[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 air outlet of the evaporator 15 is connected to the air inlet of the compressor 16, the air inlet of the evaporator 15 is connected to the air outlet of the expansion valve 17, the air inlet of the expansion valve 17 is connected to the air outlet of the condenser 18, and the air inlet of the condenser 18 is connected to the air outlet 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, and 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, and 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 circulating water pump 10 and a heat exchanger 14. The heat exchange circulating water pump 10 is connected to a water pump, the heat exchange circulating water pump 10 is connected to a hot water storage tank 5, and the heat exchanger 14 is connected to the hot water storage tank 5. The heat exchanger 14 adopts a fin-tube type; model: JN-1.

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

[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 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, and 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 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 radiation is sufficient during the day and the temperature difference between the water temperature at the outlet of the solar thermal collector 1 and the water temperature at the bottom of the hot water storage tank 5 is greater than 8°C, valve one 19 and valve two 20 are opened, the solar circulating water pump 2 is started, and the water is circulated and heated in the solar thermal 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 vacuum-treated, the three-way valve one 25 and the three-way valve two 26 are opened, the drying circulating water pump 6 is started, 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 cooled by the exhaust fan 11 after heat release, and is further cooled and dehumidified in the evaporator 15, and then 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.

[0053] Biomass boiler-heat pump drying combined operation mode: If the solar drying system stops operating on cloudy days or at night, the biomass boiler 3-heat pump drying combined operation mode is adopted; valve three 21 and valve four 22 are opened to 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 in the upper part of the heat storage tank 5 reaches the vacuum drying requirement, the vacuum pump 9 is started to vacuum the drying box 7, and the three-way valve 1 25 and the three-way valve 2 26 are opened to 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 cooled by the exhaust fan 11 after heat release, and is further cooled and dehumidified in the evaporator 15, and then 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 combined operation mode: If 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 to 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 in the upper part of the heat storage tank 5 reaches the vacuum drying requirement, the vacuum pump 9 is started to vacuum the drying box 7, 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 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 cooled by the exhaust fan 11 after heat release, and is further cooled and dehumidified in the evaporator 15, and then 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] Hot water storage tank - heat pump drying combined operation mode: If the water temperature in the upper layer of the hot water storage tank 5 can meet the drying temperature requirement, the hot water storage tank 5 - heat pump drying combined operation mode is adopted; the hot water in the hot water 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 cooled by the exhaust fan 11 after heat release, and is further cooled and dehumidified in the evaporator 15, and then 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. Under the action of the heat exchange circulation water pump 10, the hot water in the heat storage tank 5 heats the air around the evaporator 15 through the heat exchanger 14, 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] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and 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 heat collector (1), a solar circulating water pump (2), a heat storage tank (5), a drying circulating water pump (6), and a drying box (7); the solar heat collector (1) is connected to the solar circulating water pump (2), the solar circulating water pump (2) is connected to the heat storage tank (5), the solar heat collector (1) is connected to the heat storage tank (5), the heat 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 heat 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 for performing vacuum treatment on the drying box (7), the solar heat collector (1) is used for heating circulating water, and the heat storage tank (5) is used for storing 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), wherein the air outlet of the evaporator (15) is connected to the air inlet of the compressor (16), the air inlet of the evaporator (15) is connected to the air outlet of the expansion valve (17), the air inlet of the expansion valve (17) is connected to the air outlet of the condenser (18), the air inlet of the condenser (18) is connected to the air outlet 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), and 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 air source heat pump winter defrosting system, and 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. The multi-energy complementary combined drying system according to claim 1, characterized in that: The solar drying system comprises valve one (19) and valve two (20), wherein 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).

3. The multi-energy complementary combined drying system according to 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 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), and the three-way valve 2 (26) is respectively connected to the circulating water tank, the drying box (7) and valve 6 (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 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.

7. A control method for a multi-energy complementary combined drying system according to claim 1, characterized in that: Adopt the solar energy-heat pump drying joint operation mode: if the solar 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, open valve 1 (19) and valve 2 (20), start the solar circulation water pump (2), and the water circulates and heats in the solar 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, start the vacuum pump (9), vacuum the drying box (7), and open the three-way valve. Valve 1 (25) and three-way valve 2 (26) start the drying circulation water pump (6), hot water enters the drying box (7) to heat the material, and the water is discharged through the water vapor trap (8), completing the vacuum drying; at the same time, the hot and humid air discharged from the drying box (7) is cooled by the exhaust fan (11) and further cooled and dehumidified in the evaporator (15), and then 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; 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 to perform vacuum treatment on the drying box (7), the three-way valve 1 (25) and the three-way valve 2 (26) are opened, and 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), completing 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 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; 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; open valve 1 (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) to The drying oven (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, and hot water enters the drying oven (7) to heat the material, and the moisture is discharged through the water vapor trap (8), completing the vacuum drying; at the same time, the hot and humid air discharged from the drying oven (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 is sent to the drying oven (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 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, 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 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 is sent to the drying box (7) through the ventilation fan (12) to perform hot air drying of fruits and vegetables; 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) is heated by the heat exchange circulation water pump (10) through the heat exchanger (14) to heat the air around the evaporator (15), thereby preventing the heat pump from frosting and maintaining efficient operation of the system.

8. The control method of the multi-energy complementary combined drying system according to claim 7, 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.

Images