Waste heat warming large-scale vacuum freeze drying system

Abstract

The utility model relates to a waste heat warming large-scale vacuum freeze drying system which comprises a waste heat warming unit, a refrigeration unit and a vacuum unit which are connected with one another, the waste heat warming unit comprises a carbon dioxide compressor, a first plate heat exchanger, a heat storage tank, an electric auxiliary heater and a freeze-drying bin; the refrigeration unit comprises a two-stage screw compressor, a cold storage tank, an evaporative cooling tower, a second plate heat exchanger, a freezer and a third plate heat exchanger; the vacuum unit comprises a cold trap, a pre-pumping pump set and a maintaining pump set. High-temperature heating of the partition plate in the one-time drying process is achieved through waste heat warming, product quality and drying efficiency are guaranteed, and energy consumption of the freeze dryer can be greatly reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of freeze drying, and particularly relates to a large-scale vacuum freeze drying system with waste heat temperature increasing. BACKGROUND

[0002] In the modern food processing field, preserving the flavor, nutritional ingredients and extending the shelf life of food is a crucial issue. Vacuum freeze drying technology has therefore been widely used. This technology freezes food at low temperature, then sublimates in a vacuum condition, directly converting ice into water vapor, thereby greatly reducing the moisture content of food while preserving the nutritional ingredients, color and flavor of food.

[0003] At present, vacuum freeze drying equipment has been widely used in food, medicine and biological products industries. However, traditional vacuum freeze drying equipment has some shortcomings, such as high energy consumption, low efficiency, long drying process time, etc. Especially for large-scale vacuum freeze drying equipment, these shortcomings are particularly obvious, becoming a major bottleneck restricting its wide application.

[0004] The energy-saving design of large-scale vacuum freeze drying equipment needs to consider multiple complex factors, including optimization of the heating system, waste heat utilization of the refrigeration system, heat transfer efficiency, etc. Since large-scale equipment involves larger freeze drying chambers and larger water capture, the compressor generates a large amount of low-temperature waste heat (below 50℃), and traditional freeze dryers often use water cooling or air cooling to dissipate heat from the refrigeration unit, wasting the waste heat. How to utilize the waste heat in large-scale freeze drying equipment while maintaining high drying efficiency needs to be solved.

[0005] In recent years, waste heat recovery and reuse technology has been increasingly applied in industrial equipment. This technology recovers waste heat generated during equipment operation through heat exchangers and other equipment, and reuses it to improve overall energy efficiency. Currently, some freeze dryers have reused the condensation heat generated by the refrigeration system for the heating system of the freeze dryer, converting it into the heat energy required for the drying process through a heat exchanger, so that the overall energy efficiency of the system is improved. However, large-scale food freeze dryers are usually indirectly heated, with materials located between heating partitions, mainly relying on radiation heat transfer. The maximum heating temperature during the first sublimation drying process is usually between 60℃ and 95℃, the water capture of the cold trap accounts for about 70% of the total drying cycle, and the sublimation drying time accounts for about 30% of the total drying cycle. The inlet temperature of the compressor condenser of a general freeze dryer is usually less than 50℃, which cannot provide enough heat for the freeze drying sublimation stage. In addition, the efficiency of the compressor generally decreases with the increase of the difference between the condensing temperature and the evaporation temperature. By connecting a carbon dioxide heat pump in series with the refrigeration compressor, on the one hand, the condensing temperature of the refrigeration compressor can be reduced, and the refrigeration capacity can be improved; on the other hand, the partition temperature can be increased, and the drying rate can be accelerated.

[0006] Therefore, developing a new waste heat warming large-scale vacuum freeze drying equipment is an effective way to solve the problems of high energy consumption and low efficiency in the prior art. The utility model discloses a waste heat warming large-scale vacuum freeze drying system

[0007] The utility model discloses a waste heat warming large-scale vacuum freeze drying system, from the waste heat recovery angle, combine carbon dioxide heat pump technology, and then greatly improve heat utilization, reduce freeze drying energy consumption, optimize energy use through recycling and utilizing waste heat, improve overall drying efficiency.

[0008] The utility model solves its technical problem by following technical scheme:

[0009] A waste heat warming large-scale vacuum freeze drying system, comprising a waste heat warming unit, a refrigeration unit and a vacuum unit connected to each other.

[0010] The waste heat warming unit comprises a carbon dioxide compressor, a first plate heat exchanger, a heat storage tank, an electric auxiliary heater and a freeze drying bin. The condensing end of the carbon dioxide compressor is connected in parallel to the first plate heat exchanger and the heat storage tank. A fourth valve is arranged between the first plate heat exchanger and the heat storage tank. The first plate heat exchanger and the heat storage tank are respectively connected to the electric auxiliary heater through a ninth valve and a first three-way valve. The electric auxiliary heater is connected to a heating plate arranged at the left side of the freeze drying bin through a second valve. A material tray is arranged above the heating plate. The heating plate is connected to the first plate heat exchanger through a tenth valve. A cold trap bottom heater is arranged at the bottom end of a cold trap at the right side of the freeze drying bin. The cold trap bottom heater is connected to the electric auxiliary heater through a seventh valve and a first valve. An eighth valve is arranged on the heat storage tank.

[0011] The refrigeration unit comprises a double-stage screw compressor, a cold storage tank, an evaporative cooling tower, a second plate heat exchanger, a refrigeration library and a third plate heat exchanger. The evaporating end of the carbon dioxide compressor is connected to the double-stage screw compressor through the second plate heat exchanger and a second three-way valve. The second three-way valve is connected to the evaporative cooling tower. The lower ends of the second plate heat exchanger and the evaporative cooling tower are jointly connected to the third plate heat exchanger. The third plate heat exchanger is connected to the refrigeration library through a third three-way valve. The lower end of the third plate heat exchanger is connected to the cold storage tank through a fifth valve. A sixth valve is arranged on the cold storage tank.

[0012] The vacuum unit comprises a cold trap, a pre-pumping group and a maintaining pumping group, the cold trap is internally provided with a cold trap coil pipe, the cold trap coil pipe is connected to the first circulating pump, a drain valve is arranged at the bottom of the cold trap, an exhaust valve is arranged at the top of the cold trap, the upper portion of the cold trap is connected in parallel with the maintaining pumping group, the first pre-pumping group and the second pre-pumping group, and the maintaining pumping group, the first pre-pumping group and the second pre-pumping group are respectively connected with a third vacuum electromagnetic valve, a first vacuum electromagnetic valve and a second vacuum electromagnetic valve.

[0013] Moreover, a second circulating pump is arranged between the first plate heat exchanger and the heat storage tank, the lower end of the third plate heat exchanger is connected to the first circulating pump through a fifth valve, the first circulating pump is connected to the vacuum unit, and the heating plate is connected to the first plate heat exchanger through a third circulating pump.

[0014] Moreover, the lower end of the first plate heat exchanger is connected in parallel to the second plate heat exchanger and the evaporation end of the carbon dioxide compressor through a first regenerator, and a first electronic expansion valve is arranged between the first regenerator and the second plate heat exchanger.

[0015] Moreover, the lower end of the second plate heat exchanger is connected in parallel to the third plate heat exchanger, the double-stage screw compressor and the freezer through a second regenerator, and a second electronic expansion valve is arranged between the second regenerator and the third plate heat exchanger.

[0016] Moreover, the outlet end of the heating plate and the outlet end of the cold trap coil pipe are jointly connected with a third valve.

[0017] The utility model discloses a kind of advantages and beneficial effects for:

[0018] 1, the utility model discloses by recycling and using waste heat, optimization energy use, improve overall drying efficiency, provide a more efficient and energy-saving solution for modern food processing field.

[0019] 2, the utility model once drying is short time high-energy consumption process, by carbon dioxide heat pump heating recovery compressor waste heat, and ensure that material suitable heating temperature, reduce the condensation temperature of cold trap, improve compressor efficiency, reduce total energy consumption, this process can save 100% heating energy consumption, compared with traditional freeze dryer, energy saving about 40%.

[0020] 3, the utility model can realize the drying process of raw material suitable for high-temperature heating in secondary drying stage.

[0021] 4, the utility model uses the heat medium of heat storage tank to defrost operation, freeze dryer can simultaneously defrost and quick freezing operation, compared with traditional freeze dryer, shorten drying cycle about 3 hours, recover refrigeration unit waste heat in pre-freezing process simultaneously. DRAWINGS

[0022] Figure 1 The utility model discloses a structure schematic view.

[0023] Mark explanation

[0024] Maintain pump group 1, first pre -extraction pump group 2, second pre -extraction pump group 3, third vacuum electromagnetic valve 4, first vacuum electromagnetic valve 5, second vacuum electromagnetic valve 6, inlet valve 7, cold trap coil 8, cold trap 9, drain valve 10, cold trap bottom heater 11, first valve 12, electric auxiliary heater 13, heating plate 14, material tray 15, second valve 16, freeze-drying bin 17, third valve 18, first circulating pump 19, fourth valve 20, first three-way valve 21, heat storage tank 22, first plate heat exchanger 23, second circulating pump 24, first regenerator 25, first electronic expansion valve 26, carbon dioxide compressor 27, second plate heat exchanger 28, second three-way valve 29, second regenerator 30, double-stage screw compressor 31, evaporative cooling tower 32, second electronic expansion valve 33, third plate heat exchanger 34, fifth valve 35, cold storage tank 36, sixth valve 37, seventh valve 38, third three-way valve 39, freezer 40, eighth valve 41, ninth valve 42, third circulating pump 43, tenth valve 44. Specific implementation

[0025] The utility model will be further described in the following specific embodiment, the following embodiment is only descriptive, is not limitative, and this can not be limited to the protection scope of the utility model.

[0026] A waste heat temperature increasing large-scale vacuum freeze drying system, which is characterized in that it comprises a waste heat temperature increasing unit, a refrigeration unit and a vacuum unit connected with each other.

[0027] The waste heat temperature increasing unit comprises a carbon dioxide compressor 27, a first plate heat exchanger 23, a heat storage tank 22, an electric auxiliary heater 13 and a freeze-drying bin 17. The condensing end of the carbon dioxide compressor 27 is connected in parallel with the first plate heat exchanger 23 and the heat storage tank 22. A fourth valve 20 is arranged between the first plate heat exchanger 23 and the heat storage tank 22. The first plate heat exchanger 23 and the heat storage tank 22 are connected to the electric auxiliary heater 13 through a ninth valve 42 and a first three-way valve 21, respectively. The electric auxiliary heater 13 is connected to the heating plate 14 arranged at the left side of the freeze-drying bin 17 through a second valve 16. A material tray 15 is arranged above the heating plate 14. The heating plate 14 is connected to the first plate heat exchanger 23 through a tenth valve 44. A cold trap bottom heater 11 is arranged at the bottom end of the cold trap 9 at the right side of the freeze-drying bin 17. The cold trap bottom heater 11 is connected to the electric auxiliary heater 13 through a seventh valve 38 and a first valve 12. An eighth valve 41 is arranged on the heat storage tank 22.

[0028] The temperature probe is installed on the condensing end of the carbon dioxide compressor and the inlet end of the heating plate, the heat conducting oil is used as the heat conducting medium in the first, second and third plate heat exchangers, the heat medium in the heat storage tank, the heating plate, the water capturing pipeline of the cold trap and the bottom heating pipeline, and the heat conducting oil is circulated by the first, second and third circulating pumps.

[0029] The refrigeration unit comprises a double-stage screw compressor 31, a cold storage tank 36, an evaporative cooling tower 32, a second plate heat exchanger 28, a freezer 40 and a third plate heat exchanger 34, the evaporating end of the carbon dioxide compressor 27 is connected to the double-stage screw compressor 31 through the second plate heat exchanger 28 and a second three-way valve 29, the second three-way valve 29 is connected to the evaporative cooling tower 32, the lower ends of the second plate heat exchanger 28 and the evaporative cooling tower 32 are jointly connected to the third plate heat exchanger 34, the third plate heat exchanger 34 is connected to the freezer 40 through a third three-way valve 39, the lower end of the third plate heat exchanger 34 is connected to the cold storage tank 36 through a fifth valve 35, and a sixth valve 37 is arranged on the cold storage tank 36.

[0030] The vacuum unit comprises a cold trap 9, a pre-pumping group and a maintaining pump group, the cold trap coil 8 is arranged in the cold trap 9, the cold trap coil 8 is connected to the first circulating pump 19, the bottom of the cold trap 9 is provided with a drain valve 10, the top of the cold trap 9 is provided with an exhaust valve 7, the upper part of the cold trap 9 is connected in parallel to the maintaining pump group 1, the first pre-pumping group 2 and the second pre-pumping group 3, and the maintaining pump group 1, the first pre-pumping group 2 and the second pre-pumping group 3 are respectively connected to the third vacuum electromagnetic valve 4, the first vacuum electromagnetic valve 5 and the second vacuum electromagnetic valve 6.

[0031] Preferably, the second circulating pump 24 is arranged between the first plate heat exchanger 23 and the heat storage tank 22, the lower end of the third plate heat exchanger 34 is connected to the first circulating pump 19 through the fifth valve 35, the first circulating pump 19 is connected to the vacuum unit, and the heating plate 14 is connected to the first plate heat exchanger 23 through the third circulating pump 43.

[0032] Preferably, the lower end of the first plate heat exchanger 23 is connected in parallel to the second plate heat exchanger 28 and the evaporating end of the carbon dioxide compressor 27 through the first regenerator 25, and the first electronic expansion valve 26 is arranged between the first regenerator 25 and the second plate heat exchanger 28.

[0033] Preferably, the lower end of the second plate heat exchanger 28 is connected in parallel to the third plate heat exchanger 34, the double-stage screw compressor 31 and the freezer 40 through the second regenerator 30, and the second electronic expansion valve 33 is arranged between the second regenerator 30 and the third plate heat exchanger 34.

[0034] Preferably, the outlet end of the heating plate 14 is connected to the outlet end of the cold trap coil 8 with a third valve 18.

[0035] The embodiment takes the drying procedure: pre-freezing-35℃, 3 hours, drying temperature 90℃, 5 hours, drying temperature 60℃, 10 hours as an example, and the carbon dioxide waste heat recovery heating system meets the heating process.

[0036] The working process of the utility model is:

[0037] S1, pre-cooling process: connecting the two-stage screw compressor and the second plate heat exchanger, connecting the second regenerator and the freezer, the heat storage tank and the second circulating pump, starting the two-stage screw compressor and the carbon dioxide compressor, so that the temperature of the heat storage tank reaches the initial drying temperature;

[0038] S2, drying process:

[0039] Cold trap pre-cooling, the third plate heat exchanger is connected with the second regenerator, and the temperature of the cold trap is reduced to-35℃-45℃ and maintained,

[0040] (1) the frozen material is placed in the material tray of the freeze-drying bin, and the cold trap is vacuumized to a pressure below 100Pa;

[0041] (2) the pre-cooled heat conducting oil in the heat storage tank is delivered to the heating plate until the heating plate is filled with heat conducting oil, which is heated by the carbon dioxide compressor using the waste heat of the two-stage screw compressor, if the inlet temperature of the heating plate does not reach the set drying heating temperature, start the electric auxiliary heater;

[0042] (3) when the material temperature and the inlet temperature of the heating plate are consistent and remain unchanged, the drying is completed, the two-stage screw compressor and the carbon dioxide compressor are closed, and the inlet valve is opened to a pressure of 133Pa;

[0043] S3, defrosting process:

[0044] (1) close the fourth valve and the ninth valve, open the eighth valve, the second valve and the tenth valve, the first three-way valve connects the second circulating pump and the electric auxiliary heater, and the heat conducting oil is all pumped to the heat storage tank;

[0045] (2) close the eighth valve, the second valve and the tenth valve, open the sixth valve, close the fifth valve, and pump all the cold heat conducting oil to the cold storage tank;

[0046] (3) open the third valve, the ninth valve and the first valve, open the second circulating pump, so that the heat conducting oil in the cold storage tank is reduced to 0℃; close the third valve, the ninth valve and the first valve, the first three-way valve connects the second circulating pump and the electric auxiliary heater, open the electric auxiliary heater, until the ice on the surface of the cold trap coil melts and falls off;

[0047] (4) open the seventh valve, close the first valve, heat the cold trap bottom heater, melt the cold trap bottom ice water into condensed water, and the condensed water is discharged from the drain valve.

[0048] Although the embodiments and drawings of the utility model are disclosed for the purpose of illustration, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the utility model and the appended claims, therefore, the scope of the utility model is not limited to the content disclosed by the embodiments and drawings.

Claims

1. A large scale vacuum freeze drying system with waste heat warming, characterized in that: The waste heat warming unit, the refrigeration unit and the vacuum unit are connected with each other. The waste heat warming unit comprises a carbon dioxide compressor (27), a first plate heat exchanger (23), a heat storage tank (22), an electric auxiliary heater (13) and a freeze-drying chamber (17), the condensing end of the carbon dioxide compressor (27) is connected in parallel with the first plate heat exchanger (23) and the heat storage tank (22), a fourth valve (20) is arranged between the first plate heat exchanger (23) and the heat storage tank (22), the first plate heat exchanger (23) and the heat storage tank (22) are connected to the electric auxiliary heater (13) through a ninth valve (42) and a first three-way valve (21) respectively, the electric auxiliary heater (13) is connected to a heating plate (14) arranged at the left side of the freeze-drying chamber (17) through a second valve (16), a material tray (15) is arranged above the heating plate (14), and the heating plate (14) is connected to the first plate heat exchanger (23) through a tenth valve (44); a cold trap bottom heater (11) is arranged at the bottom end of a cold trap (9) at the right side of the freeze-drying chamber (17), the cold trap bottom heater (11) is connected to the electric auxiliary heater (13) through a seventh valve (38) and a first valve (12), and an eighth valve (41) is arranged on the heat storage tank (22); The refrigeration unit comprises a double-stage screw compressor (31), a cold storage tank (36), an evaporative cooling tower (32), a second plate heat exchanger (28), a refrigeration storage (40) and a third plate heat exchanger (34), the evaporating end of the carbon dioxide compressor (27) is connected to the double-stage screw compressor (31) through the second plate heat exchanger (28) and a second three-way valve (29), the second three-way valve (29) is connected to the evaporative cooling tower (32), the lower ends of the second plate heat exchanger (28) and the evaporative cooling tower (32) are connected to the third plate heat exchanger (34) in common, the third plate heat exchanger (34) is connected to the refrigeration storage (40) through a third three-way valve (39), the lower end of the third plate heat exchanger (34) is connected to the cold storage tank (36) through a fifth valve (35), and a sixth valve (37) is arranged on the cold storage tank (36); The vacuum unit comprises the cold trap (9), a pre-extraction pump group and a maintenance pump group, a cold trap coil (8) is arranged in the cold trap (9), the cold trap coil (8) is connected to a first circulating pump (19), a drain valve (10) is arranged at the bottom of the cold trap (9), an exhaust valve (7) is arranged at the top of the cold trap (9), the maintenance pump group (1), the first pre-extraction pump group (2) and the second pre-extraction pump group (3) are connected in parallel at the upper portion of the cold trap (9), and the maintenance pump group (1), the first pre-extraction pump group (2) and the second pre-extraction pump group (3) are connected to a third vacuum electromagnetic valve (4), a first vacuum electromagnetic valve (5) and a second vacuum electromagnetic valve (6) respectively. The first plate heat exchanger (23) and the heat storage tank (22) are provided with a second circulating pump (24), the lower end of the third plate heat exchanger (34) is connected to the first circulating pump (19) through a fifth valve (35), the first circulating pump (19) is connected to the vacuum unit, and the heating plate (14) is connected to the first plate heat exchanger (23) through a third circulating pump (43); The lower end of the first plate heat exchanger (23) is connected to the second plate heat exchanger (28) and the evaporation end of the carbon dioxide compressor (27) in parallel through a first regenerator (25), and a first electronic expansion valve (26) is arranged between the first regenerator (25) and the second plate heat exchanger (28); The lower end of the second plate heat exchanger (28) is connected to the third plate heat exchanger (34), the double-stage screw compressor (31) and the freezer (40) in parallel through a second regenerator (30), and a second electronic expansion valve (33) is arranged between the second regenerator (30) and the third plate heat exchanger (34); The outlet end of the heating plate (14) and the outlet end of the cold trap coil (8) are jointly connected to a third valve (18).

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