A vacuum freeze drying system based on heat pump condensation heat recovery

Abstract

The present invention relates to the technical field of drying equipment, and provides a vacuum freeze-drying system based on heat pump condensation heat recovery, comprising a dryer, a vacuum component and a heat pump component. The dryer is used to place the material to be dried. The vacuum component is connected to the dryer and is used to provide a vacuum environment for the dryer and extract moisture from the material in the dryer. The heat pump component is connected to the dryer and to the vacuum component. The heat pump component is used to provide a cold and heat source for the dryer and to transfer the latent heat of phase change in the vacuum component to the heat pump component. Waste heat is recovered by the heat pump component, and an intermediate cooler is provided in the heat pump component for heat exchange to improve system performance. A wider range of temperature control can be achieved by changing the valve opening and the start and stop of the equipment. It is also possible to integrate multiple functions such as vacuum freeze drying, vacuum drying, and vacuum pulse drying, thereby achieving product diversification.

Description

Technical Field

[0001] The present invention relates to the technical field of drying equipment, and in particular to a vacuum freeze-drying system based on heat pump condensation heat recovery. Background Art

[0002] Drying is a crucial unit operation for reducing the moisture content of materials and is an essential component of the processing of many foods, pharmaceuticals, and agricultural products. Vacuum drying involves drying materials at a pressure below standard atmospheric pressure. As the pressure decreases, the saturation temperature of water vapor decreases, allowing the moisture in the material to evaporate at low temperatures, achieving the drying effect. Vacuum freeze-drying involves first freezing the material at low temperatures (-50°C to -10°C) and then, under a high vacuum, directly sublimating the solid water content into a vapor phase to achieve drying. Drying in a low-pressure environment prevents oxidation and deterioration during the drying process and also provides disinfection and sterilization. Vacuum freeze-drying maintains the material's shape after drying, evenly distributing its constituents and creating a porous structure. Currently, vacuum freeze-drying requires a vacuum system with a refrigeration unit. The refrigeration unit's evaporation temperature is relatively low, resulting in system energy consumption far exceeding that of conventional hot air drying. Furthermore, the vacuum system requires high equipment requirements, making vacuum freeze-drying alone wasteful. Furthermore, directly discharging the latent heat of vaporization generated by the condensation and freezing of water vapor during drying and the waste heat generated by the vacuum system will lead to energy waste and high carbon emissions. Therefore, a vacuum freeze-drying system based on heat pump condensation heat recovery is urgently needed to solve the problems existing in the existing technology. Summary of the Invention

[0003] The present invention provides a vacuum freeze-drying system based on heat pump condensation heat recovery, which is used to solve the problems of excessive energy consumption and single function of the vacuum system in the prior art, so as to achieve energy-saving effect.

[0004] The present invention provides a vacuum freeze-drying system based on heat pump condensation heat recovery, comprising:

[0005] Dryer, used to place the material to be dried;

[0006] A vacuum component connected to the dryer, used to provide a vacuum environment for the dryer and extract moisture from the material in the dryer;

[0007] A heat pump component is connected to the dryer and the vacuum component. The heat pump component is used to provide a cold and hot source for the dryer and to transfer the phase change latent heat in the vacuum component to the heat pump component.

[0008] Furthermore, the dryer has a built-in heat conducting plate, which is used to place the material to be dried. The heat conducting plate is suitable for being connected to the heat pump assembly by arranging hot and cold coils.

[0009] Furthermore, the heat pump assembly includes a cold trap, a first compressor, a second compressor, a first condenser, a second condenser, a flash tank, an intercooler, a first capillary tube, a second capillary tube, a circulating pump, an auxiliary electric heater, a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, and a seventh valve; the refrigerant inlet of the first condenser is suitable for being connected to the refrigerant outlet of the first compressor through the second valve; the refrigerant outlet of the first condenser is suitable for being connected to the heat exchange coil inlet of the intercooler and to the upper inlet of the flash tank through the first valve and the first capillary tube; the third valve and the second condenser are connected in parallel with the second valve and the first condenser; the solution outlet of the first condenser is suitable for being connected to the heat coil inlet under the heat conduction plate through the auxiliary electric heater, and the solution inlet of the first condenser is suitable for being connected to the heat exchange coil inlet under the heat conduction plate through the auxiliary electric heater. The over-circulation pump is connected to the outlet of the heat coil under the heat conduction plate; the refrigerant inlet of the cold trap is suitable for being connected to the outlet of the heat exchange coil of the intercooler through the second capillary tube; the refrigerant outlet of the cold trap is suitable for being connected to the inlet of the cold coil under the heat conduction plate through the seventh valve; the refrigerant inlet of the intercooler is connected to the outlet of the cold coil under the heat conduction plate; the refrigerant outlet of the cold trap is suitable for setting a bypass pipe between the refrigerant inlet of the intercooler, and the bypass pipe is provided with the sixth valve; the refrigerant inlet of the second compressor is suitable for being connected to the gas outlet of the intercooler; the refrigerant outlet of the second compressor is suitable for being connected to the refrigerant inlet below the flash tank through the fifth valve; the refrigerant outlet of the second compressor is suitable for setting a bypass pipe between the refrigerant outlet of the first compressor, and the bypass pipe is provided with the fourth valve.

[0010] Furthermore, the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, and the seventh valve are electronic regulating valves.

[0011] Furthermore, a heat exchange coil is installed in the intercooler to exchange heat.

[0012] Furthermore, the evaporator of the heat pump system includes the cold trap and a cold pipe under the heat conduction plate.

[0013] Furthermore, the vacuum component includes a maintaining Roots pump, an evacuating Roots pump, a cold trap, a first vacuum solenoid valve, a second vacuum solenoid valve, a breaking air solenoid valve, and an air auxiliary heater; the air auxiliary heater is connected to the air inlet of the dryer through the breaking air solenoid valve; the air inlet of the cold trap is suitable for being connected to the air outlet of the dryer through the second vacuum solenoid valve; the air outlet of the cold trap is suitable for being connected to the evacuating Roots pump and the maintaining Roots pump through the first vacuum solenoid valve.

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

[0015] The present invention provides a vacuum freeze-drying system, which provides a heat source for material drying through a heat pump component, and provides a cold source for cooling the cold trap, and efficiently recovers the phase change latent heat of water vapor generated during the drying process. This part of heat can be used as a drying heat source after compression enthalpy increase, thereby realizing heat recovery and reducing the energy consumption of the system. By setting an intermediate cooler, heat exchange is performed to improve the energy efficiency of the system operation. The vacuum freeze-drying system provided by the present invention realizes temperature control of material freezing by controlling the valve opening of the sixth valve and the seventh valve; controls the single-stage or double-stage compression operation mode of the heat pump system by controlling the opening and closing of the first valve, the fourth valve, and the fifth valve and the start and stop of the first compressor; and controls the temperature of the material drying to a certain extent by controlling the valve opening of the second valve and the third valve. The vacuum freeze-drying system provided by the present invention realizes the integration of multiple functions such as vacuum freeze-drying, vacuum drying, and vacuum pulsating drying by controlling the opening of each valve and the start and stop operation of the equipment, thereby realizing diversified product production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic structural diagram of a vacuum freeze-drying system based on heat pump condensation heat recovery provided by the present invention;

[0018] Figure 2 is a schematic diagram of the system structure of the present invention in freezing mode;

[0019] Figure 3 This is a schematic diagram of the system structure of the present invention in a single-stage compression heating mode;

[0020] Figure 4 This is a schematic diagram of the system structure of the present invention in a two-stage compression heating mode;

[0021] Figure 5 It is a schematic diagram of the system structure of the present invention in a heating mode in which two-stage compression and an auxiliary electric heater are used together.

[0022] In the figure: 1. Dryer, 2. Heat conduction plate, 3. Auxiliary electric heater, 4. Circulation pump, 5. First condenser, 6. Evaporator, 7. Second condenser, 8. First compressor, 9. Flash tank, 10. Second compressor, 11. Intercooler, 12. First capillary, 13. Second capillary, 14. Maintain Roots pump, 15. Evacuate Roots pump, 16. Electronic air-breaking valve, 17. Air auxiliary heater, 18. First valve, 19. Second valve, 20. Third valve, 21. Fourth valve, 22. Fifth valve, 23. Sixth valve, 24. Seventh valve, 25. First vacuum solenoid valve, 26. Second vacuum solenoid valve, 27. Stop valve. DETAILED DESCRIPTION

[0023] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0024] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0025] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0026] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0027] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0028] The following is combined with Figure 1 The vacuum freeze drying system of the present invention is described. The vacuum freeze drying system mainly includes a dryer 1, a heat pump component and a vacuum component. The dryer 1 is used to place the material to be dried;

[0029] The vacuum component is connected to the dryer 1, and is used to provide a vacuum environment for the dryer 1 and extract moisture from the material in the dryer 1; the heat pump component is connected to the dryer 1 and to the vacuum component. The heat pump component is used to provide a cold and hot source for the dryer 1 and to transfer the latent heat of phase change in the vacuum component to the heat source component.

[0030] As attached Figure 1 As shown, the dryer 1 can be configured as a can, a box, or other shapes, as long as the interior of the dryer 1 is hollow so that the material can be placed in the dryer 1 for drying.

[0031] The dryer 1 has a built-in heat conducting plate 2, which is used to place the material to be dried. The heat conducting plate 2 is connected to the heat pump assembly by arranging hot and cold pipes. It can be understood that a hot coil for transferring heat and a cold coil for transferring cold are arranged under the heat conducting plate 2. The heat pump assembly transfers cold and heat to the heat conducting plate 2 through the hot and cold coils, and then the heat conducting plate 2 transfers the cold and heat to the material to freeze or dry the material.

[0032] According to the vacuum freeze-drying system provided by an embodiment of the present invention, the vacuum component includes a maintaining Roots pump 14, an evacuating Roots pump 15, a cold trap 6, a first vacuum solenoid valve 25, a second vacuum solenoid valve 26, a breaking air solenoid valve 16, and an air auxiliary heater 17; the air auxiliary heater 17 is connected to the air inlet of the dryer 1 through the breaking air solenoid valve 16; the air inlet of the cold trap 6 is suitable for being connected to the air outlet of the dryer 1 through the second vacuum solenoid valve 26; the air outlet of the cold trap 6 is connected to the evacuating Roots pump 15 and the maintaining Roots pump 14 through the first vacuum solenoid valve 25.

[0033] As attached Figure 1 As shown, the Roots pump 15 is evacuated to extract the air in the dryer 1, and the Roots pump 14 is maintained to maintain the stability of the vacuum degree in the drying chamber 1. The air extracted from the dryer 1 enters the cold trap 6, and the water vapor in the air condenses into water or freezes into ice in the cold trap 6. After the drying is completed, the stop valve 27 is opened to discharge the condensed water. By evacuating the Roots pump 15, maintaining the Roots pump 14, the air-breaking solenoid valve 16 and the air-assisted heater 17, the pressure pulsation in the dryer 1 is achieved. The air-breaking solenoid valve 16 breaks the vacuum degree inside the dryer 1, and the air-assisted heater 17 heats the air entering the dryer 1 after breaking the air to avoid lowering the material temperature.

[0034] In some embodiments, the heat pump assembly provides cooling and heating for the dryer 1 and provides cooling for the cold trap 6. The heat pump assembly implements various operating modes by starting and stopping the equipment and controlling the valve opening, as follows:

[0035] 1. Freezing mode: as shown in the attached Figure 2 As shown, the bold line represents the main refrigerant circulation route in freezing mode. Close first valve 18, second valve 19, fifth valve 22, and sixth valve 23, and open third valve 20, fourth valve 21, and seventh valve 24. First compressor 8 stops, and second compressor 10 starts. Refrigerant flows through cold trap 6 and the cold pipe under heat transfer plate 2, providing cooling for cold trap 6 and the material. The flow rate entering the cold pipe under heat transfer plate 2, and thus the cooling capacity provided to the material, can be controlled by adjusting the opening of sixth valve 23 and seventh valve 24. The refrigerant dissipates heat through second condenser 7.

[0036] 2. Single-stage compression heating mode: as shown in the attached Figure 3As shown, the bold line represents the main circulation route of the refrigerant in the single-stage compression heating mode. Close the first valve 18, third valve 20, fifth valve 22, and seventh valve 24, and open the second valve 19, fourth valve 21, and sixth valve 23. The first compressor 8 and auxiliary electric heater 3 stop operating, while the second compressor 10 operates. The refrigerant passes through the cold trap 6, providing cooling capacity for the cold trap. The refrigerant then exchanges heat with the solution through the first condenser 5, transferring heat from the solution to the material. The opening of the second valve 19 and third valve 20 can be controlled to control the heat exchange amount, thereby controlling the drying temperature.

[0037] 3. Two-stage compression heating mode: as shown in the attached Figure 4 As shown, the bold line represents the main circulation route of the refrigerant in the two-stage compression heating mode. The third valve 20, fourth valve 21, and seventh valve 24 are closed, while the first valve 18, second valve 19, fifth valve 22, and sixth valve 23 are opened. The auxiliary electric heater 3 stops operating, while the first compressor 8 and second compressor 10 operate. The refrigerant passes through the cold trap 6, providing cooling capacity for the cold trap 6. The refrigerant then passes through the first condenser 5 to exchange heat with the solution, thereby transferring heat to the material through the solution. The opening of the second valve 19 and third valve 20 can be controlled to control the heat exchange amount, thereby controlling the drying temperature.

[0038] 4. Heating mode with two-stage compression and auxiliary electric heater: Figure 5 As shown, the bold line represents the main circulation route in the heating mode using two-stage compression and a shared auxiliary electric heater. Close the third valve 20, fourth valve 21, and seventh valve 24, and open the first valve 18, second valve 19, fifth valve 22, and sixth valve 23. The auxiliary electric heater 3, first compressor 8, and second compressor 10 operate. The refrigerant passes through the cold trap 6, providing cooling capacity. The refrigerant then exchanges heat with the solution in the first condenser 5. The solution is then heated by the auxiliary electric heater 3 and sent to the heat pipe below the heat conducting plate 2 for heating. The amount of heat transferred is controlled by controlling the power of the auxiliary electric heater 3.

[0039] As attached Figure 1 As shown, the refrigerant is heat exchanged in the second condenser 7. The heat exchange can be performed through air or other media, as long as the heat exchange requirements with the refrigerant are met.

[0040] The vacuum freeze-drying system provided by the embodiment of the present invention realizes vacuum drying, vacuum pulse drying, and vacuum freeze-drying processes by controlling the start and stop operation of different equipment and the opening and closing of valves. The specific process is as follows:

[0041] 1. Vacuum drying process: open the dryer 1, put the material in, close the dryer 1, start the Roots pump 15 to vacuum, and when the set vacuum degree is reached, turn off the Roots pump 15, start the vacuum pump 14 to maintain the vacuum degree, start the heat pump system, run the heating mode, provide heat for the material, and dry it.

[0042] 2. Vacuum pulsation drying process: open the dryer 1, put the material in, close the dryer 1, start the evacuation Roots pump 15 to evacuate the material to reach the set vacuum degree, close the evacuation Roots pump 15, start the maintenance Roots pump 14, set the maintenance time to one, start the heat pump system, run the heating mode to provide heat for the material, dry it, reach the set maintenance time one, close the maintenance Roots pump 14, start the electronic air breaking valve 16 and the auxiliary air heater 17 to entrain air, reach the upper limit of the vacuum degree, set the maintenance time two; when the maintenance time two is reached, complete one vacuum pulsation, and then repeat the above vacuum pulsation.

[0043] 3. Vacuum freeze-drying process: open the dryer 1, put the material in, close the dryer 1, start the heat pump system, run the freezing mode, the cold trap and the material reach the set freezing temperature, start the evacuation Roots pump 15 to vacuum, reach the set vacuum degree, close the evacuation Roots pump 15, start the maintenance Roots pump 14 to maintain the vacuum degree, and run the heat pump system in the heating mode to provide heat for the material for drying.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A vacuum freeze-drying system based on heat pump condensation heat recovery, characterized in that: include: Dryer (1); A vacuum assembly connected to the dryer (1); A heat pump assembly is connected to the dryer (1) and the vacuum assembly; the dryer (1) has a built-in heat conduction plate (2), the heat conduction plate (2) is used to place the material to be dried, and the heat conduction plate (2) is connected to the heat pump assembly through a cold coil and a hot coil arranged below; the heat pump assembly includes a cold trap (6), a first compressor (8), a second compressor (10), a first condenser (5), a second condenser (7), a flash tank (9), an intercooler (11), a first capillary tube (12), a second capillary tube (13), a circulating pump (4), an auxiliary electric heater (3), a first valve (18), a second valve (19), a third valve (20), a fourth valve (21), a fifth valve (22), The sixth valve (23) and the seventh valve (24) are connected; the refrigerant inlet of the first condenser (5) is connected to the refrigerant outlet of the first compressor (8) through the second valve (19); the refrigerant outlet of the first condenser (5) is respectively connected to the heat exchange coil inlet of the intercooler (11) and is connected to the upper inlet of the flash tank (9) through the first valve (18) and the first capillary tube (12); the third valve (20) is connected in parallel to the pipeline where the second condenser (7) is located and the pipeline where the second valve (19) and the first condenser (5) are located; the solution outlet of the first condenser (5) is connected to the lower portion of the heat conduction plate (2) through the auxiliary electric heater (3). The solution inlet of the first condenser (5) is connected to the outlet of the heat coil under the heat conducting plate (2) through the circulating pump (4); the refrigerant inlet of the cold trap (6) is connected to the outlet of the heat exchange coil under the heat conducting plate (2) through the second capillary tube (13); the refrigerant outlet of the cold trap (6) is connected to the inlet of the cold coil under the heat conducting plate (2) through the seventh valve (24); the refrigerant inlet of the intercooler (11) is connected to the outlet of the cold coil under the heat conducting plate (2); a bypass pipe is provided between the refrigerant outlet of the cold trap (6) and the refrigerant inlet of the intercooler (11), and the sixth valve (23) is provided on the bypass pipe; the second pressure The refrigerant inlet of the compressor (10) is connected to the gas outlet of the intercooler (11); the refrigerant outlet of the second compressor (10) is connected to the refrigerant inlet below the flash tank (9) through the fifth valve (22); a bypass pipe is provided between the refrigerant outlet of the second compressor (10) and the refrigerant outlet of the first compressor (8), and the fourth valve (21) is provided on the bypass pipe; a heat exchange coil is provided in the intercooler (11) for heat exchange; the first valve (18), the second valve (19), the third valve (20), the fourth valve (21), the fifth valve (22), the sixth valve (23), and the seventh valve (24) are electronic regulating valves;The evaporator of the heat pump assembly includes the cold trap (6) and the cold coil under the heat conducting plate (2).

2. A vacuum freeze-drying system based on heat pump condensation heat recovery according to claim 1, characterized in that: The vacuum assembly comprises a maintaining Roots pump (14), an evacuating Roots pump (15), a cold trap (6), a first vacuum solenoid valve (25), a second vacuum solenoid valve (26), an air-breaking solenoid valve (16), and an air auxiliary heater (17); the air auxiliary heater (17) is connected to the air inlet of the dryer (1) through the air-breaking solenoid valve (16); the air inlet of the cold trap (6) is connected to the air outlet of the dryer (1) through the second vacuum solenoid valve (26); the air outlet of the cold trap (6) is connected to the evacuating Roots pump (15) and the maintaining Roots pump (14) through the first vacuum solenoid valve (25).

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