An energy-saving tobacco drying system

Abstract

An energy-saving tobacco drying system includes an evaporator, a compressor, a condenser, a main expansion valve, an electric heater, a solar collector, a regenerator, an auxiliary evaporator, and an auxiliary expansion valve; the refrigerant heat absorption main path of the evaporator, the compressor, the refrigerant heat release main path of the condenser, and the main expansion valve are connected in series through pipelines to form an air source heat pump circuit. After a part of the wet return air in the curing room is cooled step by step through the regenerator and the auxiliary evaporator, the water vapor carried is condensed into water and discharged to obtain dry return air, and the dry return air returns to the regenerator to absorb heat and heat up. The condenser receives the dry return air after dehumidification treatment, heats it further to increase the temperature, and accurately heats it to a set temperature through an electric heater and sends it to the curing room as inlet air. Another part of the return air from the curing room is sent to the solar collector for heating through a pipeline, and returns to the curing room as inlet air after the temperature rises. This system solves the problems of high energy consumption, inaccurate temperature and humidity control, and unstable quality of flue-cured tobacco in existing air source heat pump curing rooms.

Description

Technical Field

[0001] The invention relates to the technical field of energy saving, in particular to an energy-saving tobacco drying system. Background Art

[0002] my country is the country with the largest production of flue-cured tobacco in the world. At present, there are 1.2 million intensive curing barns built in the country, most of which are coal-fired, with an annual coal consumption of about 3.5 million tons. Coal-fired curing barns mostly use hot air furnaces that burn loose coal. The combustion process is unstable and the temperature rises unevenly, which is not conducive to the precise control of the tobacco curing process and affects the quality of the tobacco leaves after baking. At the same time, the high ineffective energy consumption of coal-fired curing barns leads to fuel waste and the emission of large amounts of pollutants such as SO2, NOx and solid particulate matter, causing environmental pollution. With the development of modern tobacco agriculture, more and more attention is paid to the improvement of tobacco drying technology and equipment in the tobacco leaf production process, so air source heat pump curing barn system has emerged. The existing air source heat pump tobacco curing system workflow is as follows: Figure 1 shown.

[0003] Figure 1 In the tobacco drying system, the air source heat pump system, electric heater, drying room and damper constitute the tobacco drying system. The air source heat pump system includes compressor, evaporator, condenser and expansion valve and other main components. In the air source heat pump system, the liquid refrigerant enters the evaporator to absorb the heat of the ambient air. The refrigerant absorbs heat and evaporates to become gaseous. The compressor consumes electric energy to work on the refrigerant. The refrigerant vapor pressure and temperature both increase, and then enter the condenser to condense and release heat. The process of refrigerant heat release heats the return air on the other side of the condenser, so that the return air rises to a certain temperature. The refrigerant condensed into liquid passes through the expansion valve throttling and becomes a low-temperature and low-pressure liquid again. It enters the evaporator to absorb heat again, and this cycle continues to complete the process from evaporator heat absorption to condenser heating.

[0004] Figure 1In the tobacco drying system, the return air temperature of the curing room is lower than the inlet air. The return air is first heated in the condenser in the air source heat pump system, and then assisted by the electric heater, and finally heated to the set inlet air temperature before entering the curing room. The tobacco drying process needs to ensure that the temperature and humidity of the air inside the curing room meet certain requirements. A large amount of water vapor is generated during the drying process, and the air humidity continues to increase. Excessive humidity will increase the tobacco drying cycle and affect the quality of tobacco leaves, so it is necessary to adjust the humidity of the air in the curing room. The existing air source heat pump tobacco curing system has a simple method for controlling humidity. When the air humidity is too high, the exhaust damper is opened to discharge part of the humid air in the curing room while the ambient air enters the curing room. Since the ambient air temperature is low, the air temperature in the curing room is reduced after entering the curing room. The water vapor carried by the humid air in the process of cooling down condenses, and the air moisture content decreases. Since the dehumidification process discharges humid air with a higher temperature, there is a large energy loss. At the same time, the temperature and humidity of the curing room fluctuate greatly, and the control is not accurate, which affects the quality of flue-cured tobacco. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an energy-saving tobacco drying system to solve the problems of high energy consumption, inaccurate temperature and humidity control, and unstable quality of flue-cured tobacco in existing air source heat pump curing rooms.

[0006] To achieve the above technical purpose, the technical solution adopted is: an energy-saving tobacco drying system, including an evaporator, a compressor, a condenser, a main expansion valve, an electric heater, a solar collector, a regenerator, an auxiliary evaporator, and a secondary expansion valve; the evaporator adopts a finned tube heat exchanger, the refrigerant flows inside the heat exchange tube, and the outside of the heat exchange tube including the fin part is placed in the air and directly contacts the ambient air. The ambient air provides a heat source for the evaporator.

[0007] The condenser also uses a finned tube heat exchanger, with refrigerant flowing inside the heat exchange tube and a closed type outside the heat exchange tube. The flowing medium is the dry return air from the regenerator. The evaporator refrigerant heat absorption main path, the condenser refrigerant heat release main path, the compressor and the main expansion valve are connected in series through pipelines to form an air source heat pump circuit.

[0008] The regenerator and the auxiliary evaporator both use partition-type heat exchangers. The medium on one side of the regenerator is wet return air, and the medium on the other side is dry return air from the auxiliary evaporator. The medium on one side of the auxiliary evaporator is wet return air, and the medium on the other side is refrigerant from the air source heat pump circuit.

[0009] The return air humidity of the baking room is high, which is called wet return air. After a part of the wet return air is cooled step by step through the regenerator and the auxiliary evaporator, the water vapor carried is condensed into water and discharged to obtain dry return air. The dry return air returns to the regenerator to absorb heat and heat up. A part of the return air of the baking room is cooled through the wet return air path of the regenerator and the wet return air path of the auxiliary evaporator, and the dry return air is obtained at the outlet of the auxiliary evaporator. The dry return air absorbs heat and heats up through the dry return air path of the regenerator and enters the condenser. The condenser in the air source heat pump circuit receives the dry return air after dehumidification treatment, heats it further to increase the temperature, and the high temperature dry return air is then accurately heated to the set temperature by the electric heater and sent to the baking room as the inlet air. A part of the refrigerant at the outlet of the condenser refrigerant heat release main path is throttled by the main expansion valve, and the other part of the refrigerant is throttled by the auxiliary expansion valve. The refrigerant is connected to the refrigerant path of the auxiliary evaporator through the auxiliary expansion valve, and the outlet of the refrigerant path of the auxiliary evaporator is connected to the pipeline between the main expansion valve and the evaporator.

[0010] Another part of the return air from the baking room is sent to the solar collector through the pipeline for heating, and then returns to the baking room as intake air after the temperature rises.

[0011] A drain port is provided at the outlet of the wet return air path of the auxiliary evaporator.

[0012] A drain port is provided at the outlet of the wet return air path of the regenerator.

[0013] After the solar collector heats the return air, the circulating fan delivers the incoming air to the oven. The electric heater further heats the return air to the set inlet air temperature and delivers the incoming air to the oven through the main circulating fan.

[0014] The beneficial effects of the present invention are:

[0015] The energy-saving tobacco drying system used in the present invention is as follows Figure 2 As shown, the system is mainly composed of a compressor, an evaporator, a condenser, a main expansion valve, an auxiliary expansion valve, a solar collector, a regenerator and an auxiliary evaporator, an electric heater, etc.

[0016] The solar collector adopted in the present invention utilizes solar energy to heat the return air of the curing room, thereby reducing the power consumption of the system and lowering the cost of curing tobacco.

[0017] The heat regenerator and auxiliary evaporator adopted in the present invention can realize the closed circulation of hot air in the flue-cured tobacco system, and the dehumidification process does not need to discharge hot air, so the energy loss is small and the energy consumption is low.

[0018] The air closed circulation system adopted by the present invention removes moisture by lowering the return air temperature. The dehumidification process is continuous and stable, which is conducive to the precise control of the temperature and humidity of the flue-curing room, the flue-curing process is stable, and the flue-cured tobacco quality is reliable and guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a structural schematic diagram of the prior art;

[0020] Figure 2 It is a structural schematic diagram of the present invention;

[0021] In the figure: 1. baking room, 2. compressor, 3. evaporator, 4. condenser, 5. main expansion valve, 6. electric heater, 7. main circulation fan, 8. solar collector, 9. circulation fan, 10. regenerator, 11. auxiliary evaporator, 12. auxiliary expansion valve, 13. exhaust damper. DETAILED DESCRIPTION

[0022] like Figure 2 As shown, an energy-saving tobacco drying system is mainly composed of a drying room 1, a compressor 2, an evaporator 3, a condenser 4, a main expansion valve 5, an electric heater 6, a main circulation fan 7, a solar collector 8, a circulation fan 9, a regenerator 10, an auxiliary evaporator 11, and a secondary expansion valve 12. The solar collector 8 and the circulation fan 9 together constitute a solar heating system, and the compressor 2, the evaporator 3, the condenser 4 and the main expansion valve 5 constitute an air source heat pump system. The medium on one side of the evaporator is the refrigerant, and the other side is placed in the ambient air. The air provides a heat source for the evaporation of the refrigerant. One side of the evaporator 3 provides a heat source through the ambient air. The other side of the evaporator 3 is the refrigerant heat absorption main path, one side of the condenser 4 is the dry return air from the regenerator, and the other side of the condenser 4 is the refrigerant heat release main path. The evaporator refrigerant heat absorption main path, the condenser refrigerant heat release main path, the compressor 2, the condenser 4 and the main expansion valve 5 are connected in series through pipelines to form an air source heat pump circuit.

[0023] In the air source heat pump system, the liquid refrigerant enters the evaporator 3 to absorb the heat of the ambient air. The refrigerant absorbs heat and evaporates to become a medium-temperature medium-pressure gaseous refrigerant. The compressor 2 consumes electrical energy to do work on the refrigerant. The refrigerant vapor pressure and temperature both increase to become a high-temperature and high-pressure gaseous refrigerant. Then, it enters the condenser 4 to condense and release heat to heat the dry return air from the regenerator on the other side. After releasing heat, the refrigerant becomes a low-temperature and high-pressure liquid refrigerant. After throttling through the main expansion valve 5, it becomes a low-temperature and low-pressure liquid refrigerant again. This cycle continues, completing the process from absorbing heat in the evaporator 3 to releasing heat in the condenser 4.

[0024] In the solar heating system, part of the return air from the baking room 1 enters the solar collector 8, is heated by solar energy, and the return air temperature is increased as the intake air, which is then transported to the baking room by the circulating fan 9. Another part of the return air from the baking room 1 is cooled by the regenerator 10 and the auxiliary evaporator 11, and then heated by the regenerator 10, the condenser 4 and the electric heater 6, and the intake air with a higher temperature is transported to the baking room 1 by the main circulating fan 7. The specific implementation process is: another part of the wet return air from the baking room 1 passes through the wet return air path of the regenerator 10 to exchange heat with the dry return air with a lower temperature from the auxiliary evaporator 11, the temperature of the wet return air at the outlet of the regenerator 10 is reduced, and then the wet return air enters the auxiliary evaporator 11 again to exchange heat with the refrigerant from the air source heat pump system, the temperature is further reduced and the humidity is reduced, and it becomes dry return air at the outlet of the wet return air path of the auxiliary evaporator 11. The heating path of the condenser 4 receives the dry return air from the regenerator and heats it to further increase its temperature. The higher temperature dry return air is finally accurately heated to the set inlet air temperature by the electric heater 6. At this time, it serves as the inlet air of the baking room 1 and is delivered to the baking room 1 through the main circulation fan 7.

[0025] A large amount of water evaporates during the tobacco drying process. The moisture content of the return air from the drying room 1 is relatively high. The wet return air enters the regenerator 10 and the auxiliary evaporator 11 in turn for cooling. The temperature of the wet return air is relatively low at the outlet of the regenerator 10. More than 95% of the water vapor in the wet return air condenses into water, which is collected and discharged. The temperature of the wet return air is further reduced at the outlet of the auxiliary evaporator 11, and the water vapor in the wet return air further condenses into water, which is collected and discharged at the outlet of the auxiliary evaporator 11. At this time, the volume ratio of water vapor in the return air drops to an extremely low level, which is called dry return air.

[0026] The refrigerant heat release main path of the condenser 4 is connected to the refrigerant path of the auxiliary evaporator 11 through the main expansion valve 5, and the refrigerant path outlet of the auxiliary evaporator 11 is connected to the pipeline between the main expansion valve 5 and the evaporator 3. In the auxiliary evaporator 11, the high-pressure and low-temperature liquid refrigerant from the condenser 4 of the air source heat pump system is throttled by the auxiliary expansion valve 12 to become a low-temperature and low-pressure refrigerant. The low-temperature and low-pressure refrigerant enters the auxiliary evaporator 11 to absorb heat, further reducing the temperature of the wet return air on the other side, condensing the water vapor carried by the wet return air, and becoming dry return air at the wet return air path outlet of the auxiliary evaporator 11.

[0027] In the regenerator 10, the wet return air with higher temperature and humidity in the wet return air path of the regenerator 10 exchanges heat with the dry return air with lower temperature from the auxiliary evaporator 11. The dry return air sent out from the dry return air path of the regenerator 10 is heated up and then enters the condenser 4 in the air source heat pump system to absorb heat, and is further heated by the electric heater 6. The return air temperature is increased to the set inlet air temperature. When the inlet conditions are met, the main circulation fan 7 delivers the inlet air to the baking room 1, thereby forming a closed circulation system for return air.

[0028] In the circulation process in which the return air is cooled through the regenerator 10 and the auxiliary evaporator 11, then heated through the regenerator 10, the condenser 4 and the electric heater 6 and then returns to the baking room 1, the return air temperature first decreases and then increases. During the entire circulation process, only condensed water is discharged, and no additional hot air is discharged, so the heat loss is small and the energy utilization rate is high.

[0029] The present invention is suitable for intensive tobacco drying barns, and specifically solves the problems of large heat loss, high energy consumption, unstable temperature and humidity control in the dehumidification process of conventional air source heat pump barn systems. It can greatly reduce the energy consumption cost of the tobacco drying system and improve the quality of the tobacco leaves after baking.

Claims

1. An energy-saving tobacco drying system, characterized in that: Including evaporator, compressor, condenser, main expansion valve, electric heater, solar collector, regenerator, auxiliary evaporator, auxiliary expansion valve; The medium on one side of the evaporator is refrigerant, and the other side is placed in the ambient air. The air provides a heat source for the evaporation of the refrigerant. The refrigerant heat absorption main path of the evaporator, the compressor, the refrigerant heat release main path of the condenser and the main expansion valve are connected in series through pipelines to form an air source heat pump circuit. A part of the return air from the baking room is cooled down through the wet return air path of the regenerator and the wet return air path of the auxiliary evaporator, and dry return air is obtained at the outlet of the auxiliary evaporator. The dry return air absorbs heat and heats up through the dry return air path of the regenerator, and then enters the condenser. The condenser receives the dry return air after dehumidification. The refrigerant in the condenser releases heat in the main heat release path to heat the dry return air. The dry return air is then heated to the set temperature by the electric heater and sent to the baking room as the inlet air. A part of the refrigerant at the outlet of the refrigerant release main path of the condenser enters the main expansion valve, and the other part of the refrigerant is connected to the refrigerant path of the auxiliary evaporator through the auxiliary expansion valve. The outlet of the refrigerant path of the auxiliary evaporator is connected to the pipeline between the main expansion valve and the evaporator. Another part of the return air from the baking room is sent to the solar collector through the pipeline for heating, and then returns to the baking room as the intake air; A drain port is provided at the outlet of the wet return air path of the auxiliary evaporator.

2. An energy-saving tobacco drying system according to claim 1, characterized in that: A drain port is provided at the outlet of the wet return air path of the heat regenerator.

3. An energy-saving tobacco drying system according to claim 1, characterized in that: The solar collector heats the return air and then delivers the incoming air to the baking room through the circulating fan.

4. An energy-saving tobacco drying system according to claim 1, characterized in that: The electric heater further heats the return air to the set inlet air temperature, and the inlet air is transported to the baking room through the main circulation fan.

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