Heat pump dryer

Abstract

The utility model relates to a heat pump drying machine which comprises a drying device and at least one heat pump unit. A circulating air pipe and an air return pipe are arranged between the drying device and each heat pump unit, and the two ends of the circulating air pipe are connected with the top of the drying device and the tops of the heat pump units correspondingly. Two ends of the air return pipe are respectively connected with the bottoms of the drying device and the heat pump unit; the heat pump unit comprises a heating mechanism, a circulating fan is arranged above the heating mechanism, the circulating fan is connected with a circulating air pipe, the air return pipe is used for conveying air at the bottom of the drying device to the heat pump unit, and the heating mechanism is used for heating the air conveyed to the heat pump unit by the air return pipe; the circulating fan is used for conveying air heated by the heating mechanism to the top of the drying device through the circulating air pipe. According to the utility model, the heat pump unit is directly arranged on the circulating air pipe, so that matched equipment for steam heating is saved, heat loss is reduced, the drying cost of rice and flour products is effectively reduced, and the structure of the drying machine is more compact.

Description

Technical Field

[0001] The utility model relates to the technical field of drying equipment, in particular to a heat pump dryer. Background Art

[0002] The production process of rice and flour products involves multiple steps, mainly including raw material preparation, pulping, extrusion dehydration, forming, cutting, drying, packaging and storage, etc. Among them, the drying process is a very important step in the production process of rice and flour products, because the water content of rice and flour products is high before drying and they are not suitable for long-term storage. Therefore, it is necessary to dry the rice and flour products to reduce the moisture content during the production process, so as to increase the storage time.

[0003] Generally, rice and flour products are dried by loading the products into hanging boxes and then transporting them together with the hanging boxes to the inside of the dryer for drying. The existing dryers require a lot of supporting equipment and have a complex structure. The long conveying pipeline also increases the heat loss. The existing technology uses steam as the heating medium, and the cost of burning steam by the boiler is high, and waste gas pollution will also be generated.

[0004] Therefore, it is necessary to develop a heat pump dryer with a simple structure, which can reduce the drying cost and improve the drying efficiency. Content of the Utility Model

[0005] Aiming at the problems existing in the prior art, the purpose of the utility model is to provide a heat pump dryer with a simple and compact structure, which is more environmentally friendly and can effectively improve the drying efficiency and reduce the production cost.

[0006] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0007] A heat pump dryer includes a drying device and at least one heat pump unit;

[0008] A circulation air duct and a return air duct are provided between the drying device and each heat pump unit. The two ends of the circulation air duct are respectively connected to the top of the drying device and the top of the heat pump unit; the two ends of the return air duct are respectively connected to the bottom of the drying device and the bottom of the heat pump unit;

[0009] The heat pump unit includes a heating mechanism, a circulation fan is arranged above the heating mechanism, and the circulation fan is connected to the circulation air duct. Among them, the return air duct is used to convey the air at the bottom of the drying device to the heat pump unit, and the heating mechanism is used to heat the air conveyed to the heat pump unit by the return air duct; the circulation fan is used to convey the air heated by the heating mechanism to the top of the drying device through the circulation air duct.

[0010] Furthermore, an air inlet is opened at the top of the drying device, and the air inlet is connected to the circulation air duct; an air return opening is opened at the bottom of the drying device, and the air return opening is connected to the return air duct.

[0011] Further, a moisture exhaust port is provided at the bottom of the drying device, and the moisture exhaust port is connected to a moisture exhaust fan.

[0012] Further, an adjustable air supply port is provided on the return air duct, and the adjustable air supply port is used to control the amount of air entering the return air duct.

[0013] Further, an air supply port is provided at the top of the heat pump unit, and the upper and lower ends of the air supply port are respectively connected to the circulation fan and the heating mechanism.

[0014] Further, the heat pump unit includes a condenser, an endothermic evaporator and a compressor, the heating mechanism is the condenser, and the condenser, the endothermic evaporator and the compressor are sequentially connected to form a closed loop; a heat transfer medium is installed in the closed loop.

[0015] Further, a throttling element is provided between the condenser and the endothermic evaporator to control the flow rate of the heat transfer medium.

[0016] Further, at least one air distribution partition is provided in the circulation air duct to evenly guide the heated air in the circulation air duct into the drying device.

[0017] Further, a temperature sensor is installed on the circulation air duct, and the temperature sensor is connected to the heat pump unit.

[0018] Generally speaking, the present utility model has the following advantages: When in use, the heat pump unit receives low-temperature air from the bottom of the drying device. After the low-temperature air passes through the heating mechanism of the heat pump unit, the temperature is raised to form high-temperature air. The circulation fan blows the high-temperature air into the circulation air duct, and the high-temperature air enters the interior of the drying device through the circulation air duct. The high-temperature air flows from the top to the bottom of the drying device. During this process, the material (such as the rice and flour products to be dried) placed in the drying device exchanges heat with the high-temperature air. The moisture of the material absorbs the heat of the high-temperature air and evaporates into water vapor, so that the material is dried. When the high-temperature air exchanges heat with the material, it is absorbed by the material and the temperature drops to become low-temperature air. The low-temperature air sinks to the bottom of the dryer and is then transported back to the heat pump unit through the return air duct for heating, and so on in a cycle. The present utility model abandons the conventional heating and drying method for rice and flour products using steam as the heating medium, and instead uses a heat pump unit to absorb the heat energy in the air for use by the dryer, and uses the dryer to dry the material. There is no need to install a boiler, the drying efficiency is higher, there is no pollution, and it is more environmentally friendly. Compared with the need for a lot of supporting equipment when using a boiler, the present utility model directly installs the heat pump unit on the circulation air duct, saves the supporting equipment for steam heating, reduces heat loss, effectively reduces the drying cost of rice and flour products, and the dryer structure is more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the present utility model;

[0020] In the figure:

[0021] 1 - drying device; 11 - air inlet; 12 - air return opening; 13 - moisture exhaust opening;

[0022] 2 - heat pump unit; 21 - circulation fan; 22 - air supply opening; 23 - condenser; 24 - heat absorption evaporator; 25 - compressor; 26 - throttling element;

[0023] 3 - circulation air duct; 31 - air distribution partition; 32 - temperature sensor;

[0024] 4 - air return duct; 41 - adjustable air supply opening;

[0025] 5 - moisture exhaust fan. Detailed implementation mode

[0026] The following will further elaborate on the present utility model in detail.

[0027] As Figure 1 shown, a heat pump dryer includes a drying device 1 and at least one heat pump unit 2;

[0028] A circulation air duct 3 and an air return duct 4 are provided between the drying device 1 and each heat pump unit 2. The two ends of the circulation air duct 3 are respectively connected to the top of the drying device 1 and the top of the heat pump unit 2; the two ends of the air return duct 4 are respectively connected to the bottom of the drying device 1 and the bottom of the heat pump unit 2; the drying device 1, the air return duct 4, the heat pump unit 2 and the circulation air duct 3 form a loop;

[0029] The heat pump unit 2 includes a heating mechanism. A circulation fan 21 is provided above the heating mechanism. The circulation fan 21 is connected to the circulation air duct 3. Among them, the air return duct 4 is used to convey the air at the bottom of the drying device 1 to the heat pump unit 2, and the heating mechanism is used to heat the air conveyed to the heat pump unit 2 by the air return duct 4; the circulation fan 21 is used to convey the air heated by the heating mechanism to the top of the drying device 1 through the circulation air duct 3.

[0030] An air inlet 11 is opened at the top of the drying device 1, and the air inlet 11 is connected to the circulation air duct 3; an air return opening 12 is opened at the bottom of the drying device 1, and the air return opening 12 is connected to the air return duct 4. A moisture exhaust opening 13 is also opened at the bottom of the drying device 1, and the moisture exhaust opening 13 is connected to a moisture exhaust fan 5. The moisture exhaust fan 5 is used to discharge the wet air inside the drying device 1.

[0031] An adjustable air supply opening 41 is opened on the air return duct 4. The adjustable air supply opening 41 is used to control the air volume entering the air return duct 4 and supplement the discharged wet air to ensure the drying effect.

[0032] An air outlet 22 is provided at the top of the heat pump unit 2. The upper and lower ends of the air outlet 22 are respectively connected to the circulation fan 21 and the heating mechanism. The heat pump unit 2 includes a condenser 23, an endothermic evaporator 24 and a compressor 25. The heating mechanism is the condenser 23. The condenser 23, the endothermic evaporator 24 and the compressor 25 are connected in sequence to form a closed loop; a heat transfer medium is installed in the closed loop. A throttling element 26 is provided between the condenser 23 and the endothermic evaporator 24 to control the flow rate of the heat transfer medium.

[0033] At least one air distribution partition 31 is provided in the circulation air duct 3 to evenly guide the heated air in the circulation air duct 3 to the drying device 1, so as to dry the product evenly. A temperature sensor 32 is installed on the circulation air duct 3, and the temperature sensor 32 is connected to the heat pump unit 2. Specifically, the temperature sensor 32 is arranged on the side close to the heat pump unit 2 to sense the temperature of the just-heated air. The throttling element 26 is connected to the temperature sensor 32. The throttling element 26 adjusts the flow rate of the heat transfer medium in the heating mechanism according to the information fed back by the temperature sensor 32, so as to adjust the heat exchange temperature of the condenser 23.

[0034] The working principle of the present utility model: Put the material into the powder box, and the powder box is conveyed by the conveying equipment into the drying device 1. Start the heat pump unit 2. The circulation fan 21 above the heat pump unit 2 conveys the low-temperature air in the drying device 1 to the inside of the heat pump unit 2 through the return air duct 4. At the same time, the heating mechanism of the heat pump unit 2 operates. The heat transfer medium of the heating mechanism evaporates and expands in the endothermic evaporator 24 to absorb the heat of the air. The expanded heat transfer medium is compressed by the compressor 25, and the temperature of the compressed heat transfer medium rises. The heat transfer medium with the increased temperature is sent to the condenser 23. The low-temperature air in the heat pump unit 2 exchanges heat with the high-temperature heat transfer medium on the surface of the condenser 23, and the low-temperature air is heated into high-temperature air. The circulation fan 21 blows the high-temperature air to the circulation air duct 3, and the air distribution partition 31 of the circulation air duct 3 evenly sends the high-temperature air into the drying device 1. The moisture of the material evaporates into water vapor after absorbing the heat of the high-temperature air, so as to achieve the drying effect. The moisture exhaust fan 5 discharges the water vapor out of the drying device 1 through the moisture exhaust port 13. After the material absorbs the heat of the high-temperature air, the high-temperature air becomes low-temperature air. The low-temperature air flows to the bottom of the drying device 1 and is then conveyed to the inside of the heat pump unit 2 through the return air duct 4, and this cycle continues.

[0035] When high-temperature air passes through the circulation air duct 3, the temperature sensor 32 senses the temperature change in the circulation air duct 3 and feeds back a signal to the throttling element 26. When the temperature in the circulation air duct 3 is relatively low, the throttling element 26 controls to accelerate the flow rate of the heat transfer medium, improve the heat supply, and increase the temperature of the high-temperature air after heat exchange. When the temperature in the circulation air duct 3 is relatively high, the temperature sensor 32 sends a signal, and the throttling element 26 reduces the flow rate of the heat transfer medium, reduces heat exchange, and thus lowers the temperature of the high-temperature air, achieving the effect of precise temperature control.

[0036] The present utility model changes the previous heating method using steam as the heating medium. The dryer has a compact structure, does not require the installation of a boiler, has higher drying efficiency and no pollution, and effectively reduces the drying cost.

[0037] The present utility model is provided with a temperature sensor 32 and an exhaust fan 5, and can precisely control the temperature and humidity of the drying device 1.

[0038] The above embodiments are the preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present utility model shall be equivalent replacement methods and are all included in the protection scope of the present utility model.

Claims

1. A heat pump dryer, characterized in that: It includes a drying device and at least one heat pump unit; A circulation air duct and a return air duct are provided between the drying device and each heat pump unit. The two ends of the circulation air duct are respectively connected to the top of the drying device and the top of the heat pump unit; the two ends of the return air duct are respectively connected to the bottom of the drying device and the bottom of the heat pump unit; The heat pump unit includes a heating mechanism. A circulation fan is provided above the heating mechanism, and the circulation fan is connected to the circulation air duct. Among them, the return air duct is used to transport the air at the bottom of the drying device to the heat pump unit, and the heating mechanism is used to heat the air transported to the heat pump unit by the return air duct; the circulation fan is used to transport the air heated by the heating mechanism to the top of the drying device through the circulation air duct.

2. The heat pump dryer according to claim 1, wherein: An air inlet is provided at the top of the drying device, and the air inlet is connected to the circulation air duct; an air return opening is provided at the bottom of the drying device, and the air return opening is connected to the return air duct.

3. The heat pump dryer according to claim 2, wherein: A moisture discharge port is also provided at the bottom of the drying device, and a moisture discharge fan is connected to the moisture discharge port.

4. The heat pump dryer according to claim 3, characterized in that: An adjustable air supply compensation opening is provided on the return air duct, and the adjustable air supply compensation opening is used to control the air volume entering the return air duct.

5. A heat pump dryer according to claim 1, characterized in that: An air supply opening is provided at the top of the heat pump unit, and the upper and lower ends of the air supply opening are respectively connected to the circulation fan and the heating mechanism.

6. The heat pump dryer according to claim 5, wherein: The heat pump unit includes a condenser, an endothermic evaporator and a compressor. The heating mechanism is the condenser, and the condenser, the endothermic evaporator and the compressor are sequentially connected to form a closed loop; a heat transfer medium is installed in the closed loop.

7. The heat pump dryer according to claim 6, characterized in that: A throttling element is provided between the condenser and the endothermic evaporator to control the flow rate of the heat transfer medium.

8. A heat pump dryer according to claim 1, characterized in that: At least one air distribution partition is provided in the circulation air duct to evenly guide the heated air in the circulation air duct into the drying device.

9. The heat pump dryer according to claim 8, wherein: A temperature sensor is installed in the circulation air duct, and the temperature sensor is connected to the heat pump unit.

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