A juice-pomace vacuum-superheated steam closed-circuit drying system and method

Abstract

The present invention relates to a juice-pomace vacuum-superheated steam closed-loop circulation drying system, wherein the hot juice outlet pipe of the juice preheater is connected to the material inlet of the vacuum belt dryer and connected to the upper surface of the first conveyor belt mechanism through a juice delivery pump; the first steam outlet pipeline of the steam generator is connected to the outer jacket of the preheater; the second steam outlet pipeline of the steam generator is connected to the vacuum belt dryer; the secondary steam outlet of the vacuum belt dryer is pressurized and heated by the first vacuum pump and the steam compressor and then delivered to the low-pressure superheated steam belt dryer. The present invention adopts a vacuum belt dryer to dry juice, and recycles the waste heat of the secondary steam after the vacuum belt dryer is dried, which is used to dry the pomace with superheated steam, thereby maximizing energy utilization, and realizing the joint drying of juice and pomace at the same time, achieving a steam recovery rate of 85%, a drying system thermal efficiency of 70% to 85%, and a material utilization rate of 90%.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit and vegetable drying, and in particular relates to a juice-pomace vacuum-superheated steam closed-circuit circulation drying system and method. Background Art

[0002] At present, there are two methods for preparing fruit and vegetable powder. One is to dry the whole fruit and then crush it, and the other is to squeeze the fruit juice or pulp it and then dry it to obtain powder. However, the fruit powder obtained by the first method has poor solubility, and the fruit residue of the second method is usually not well recycled, resulting in a large amount of waste. Reducing the waste of materials on the basis of increasing the solubility of fruit powder is a practical problem that needs to be solved urgently.

[0003] For the drying of juice pomace, temperature is the main factor affecting its quality, so the drying temperature should not be too high. Taking apple juice drying as an example, a vacuum belt drying system is used for drying. The environment is in a low vacuum state. When the vacuum degree is 4kPa, the boiling point of water is 29℃, which well protects the nutrients in the juice.

[0004] However, in the existing vacuum belt drying system, the secondary steam after material drying is not well utilized. The secondary steam is often simply condensed and recycled, which fails to maximize steam utilization.

[0005] Therefore, how to effectively utilize secondary steam, maximize the recovery of steam waste heat, realize energy recycling, and simultaneously complete the combined drying of juice and pomace is the main technical problem to be solved in this field. Summary of the invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and provide a juice-pomace vacuum-superheated steam closed-loop circulation drying system, which adopts a vacuum belt dryer to dry the juice, and recovers the waste heat of the secondary steam after the vacuum belt dryer is dried, which is used to dry the pomace with superheated steam, thereby maximizing energy utilization and realizing the combined drying of juice and pomace.

[0007] The present invention solves the technical problem by the following technical solutions:

[0008] A juice-pomace vacuum-superheated steam closed-loop drying system, characterized in that it comprises a juice preheater, a juice delivery pump, a steam generator, a vacuum belt dryer, a first vacuum pump, a steam compressor, a low-pressure superheated steam belt dryer, and a second vacuum pump; the hot juice outlet pipe of the juice preheater is connected to the material inlet of the vacuum belt dryer and to the upper surface of the first conveyor belt mechanism through the juice delivery pump; the first steam outlet pipe of the steam generator is connected to the outer jacket of the preheater; the second steam outlet pipe of the steam generator is connected to the The first steam inlet of the vacuum belt dryer; the secondary steam outlet of the vacuum belt dryer is transported to the low-pressure superheated steam belt dryer after being pressurized and heated by the first vacuum pump and the steam compressor, the low-pressure superheated steam outlet of the low-pressure superheated steam belt dryer is connected to the outer jacket of the preheater through the second vacuum pump, and the condensate outlet pipe of the outer jacket of the juice preheater is connected back to the cold water inlet of the steam generator; the material outlet of the vacuum belt dryer is equipped with a first material receiving mechanism, and the material outlet of the low-pressure superheated steam belt dryer is equipped with a second material receiving mechanism.

[0009] Moreover, the vacuum belt dryer is provided with a three-layer conveyor belt, and the bottom of the three-layer conveyor belt in the vacuum belt dryer is sequentially provided with a first heating zone, a second heating zone, a third heating zone and a cooling zone from the material inlet to the material outlet, and the first heating zone, the second heating zone, the third heating zone and the cooling zone are all a first heating plate, a second heating plate, a third heating plate and a cooling plate with a cavity for the circulation of a heating medium; the second steam outlet pipeline of the steam heater is connected to the first heating zone; the third steam outlet pipeline of the steam heater is connected to the second heating zone after passing through a first branch and a first shell and tube heat exchanger, and is connected to the third heating zone after passing through a second branch and a second shell and tube heat exchanger, and the cooling zone is connected to a cold water source, and the cold water generated in the first heating zone, the second heating zone and the third heating zone are all transported back to the steam generator, and the cold water generated in the first shell and tube heat exchanger and the second shell and tube heat exchanger are transported back to the cold water inlet of the steam generator, and the cold water in the cooling zone is returned to the factory for daily water use.

[0010] Moreover, a material cutting mechanism is arranged at the material outlet end of the vacuum belt dryer.

[0011] A drying method using the juice-pomace vacuum-superheated steam closed-circuit drying system comprises the following steps:

[0012] 1) Juice preheating: Turn on the steam generator and supply saturated steam to the outer jacket of the preheater. After the saturated steam fills the outer jacket of the preheater, the juice enters the preheater through the cold juice inlet pipe 12 and is stirred by the stirrer to be evenly heated. The temperature is preheated from room temperature to 40-45°C;

[0013] 2) Juice vacuum belt drying: The preheated juice is conveyed to the first conveyor belt mechanism of the vacuum belt dryer by the juice conveying pump, and passes through the first heating zone, the second heating zone, the third heating zone and the cooling zone in sequence. The juice is gradually dried into dry powder. The obtained dry product is cut by the cutting mechanism and the dry powder is collected by the first receiving device;

[0014] 3) Secondary steam recompression: A large amount of secondary superheated steam generated by the juice drying in the vacuum belt dryer is pumped to the steam compressor by the first vacuum pump, and the low-pressure superheated steam of about 50°C is compressed to low-pressure superheated steam of about 70°C;

[0015] 4) Superheated steam belt drying of pomace: The compressed low-pressure superheated steam enters from the bottom of the superheated steam belt dryer and serves as a heat source to heat and dry the pomace. The pomace is transported by the second conveyor belt mechanism in the superheated steam belt dryer. After being evenly distributed, the superheated steam evenly heats the pomace. The dried product is collected by the second receiving mechanism.

[0016] 5) Recycling of superheated steam: The secondary low-pressure superheated steam generated during the pomace superheated steam belt drying process is pumped by the second vacuum pump to the outer jacket of the preheater as a heat source to heat the cold juice;

[0017] 6) Heating by steam generator: the saturated steam generated by the steam generator is supplied to the outer jacket of the preheater through the first steam outlet at the initial stage of drying; the saturated steam generated by the steam generator is supplied to the first heating zone in the vacuum belt dryer through the second steam outlet as a heat exchange medium; the saturated steam generated by the steam generator is supplied to the first shell and tube heat exchanger and the second shell and tube heat exchanger through the third steam outlet as a heat source to heat cold water to hot water of a certain temperature, and the obtained hot water of different temperatures is used as the heat exchange medium of the second heating zone and the third heating zone of the vacuum belt dryer;

[0018] 7) Water recycling process: the condensed water produced by the outer jacket of the preheater in step 5), the cold water produced by the first heating zone, the second heating zone, and the third heating zone are all transported back to the steam generator, and the condensed water produced by the first shell and tube heat exchanger and the second shell and tube heat exchanger are transported back to the steam generator through pipelines as supplementary water, and are recycled after being heated to saturated steam.

[0019] The advantages and beneficial effects of the present invention are:

[0020] 1. In the juice-pomace vacuum-superheated steam closed-loop drying system of the present invention, the secondary steam outlet of the vacuum belt dryer is pressurized and heated by the first vacuum pump and the steam compressor and then transported to the low-pressure superheated steam belt dryer, thereby maximizing the use of the waste heat of the superheated steam generated during the juice drying process and improving energy utilization.

[0021] 2. The juice-pomace vacuum-superheated steam closed-loop drying system of the present invention adopts a vacuum belt dryer, a first vacuum pump, a steam compressor, and a low-pressure superheated steam belt dryer to jointly dry the juice and the pomace, thereby solving the problem that the pomace cannot be fully utilized after juicing the fruit. After the juice and the pomace are dried, they are formed into dry powder through the first material receiving device and the second material receiving device.

[0022] 3. In the juice-pomace vacuum-superheated steam closed-loop drying system of the present invention, the secondary steam after all drying is completed can be returned to the outer jacket of the preheater to preheat the juice, and the condensed water generated therefrom is fully utilized as supplementary water for the steam generator. The condensed water generated by the steam generator after heat exchange through the first and second shell and tube heat exchangers is also fully utilized as supplementary water for the steam generator, thereby saving water resources.

[0023] 4. The juice-pomace vacuum-superheated steam closed-loop drying system and method of the present invention adopts a vacuum belt dryer to dry the juice, and recovers the waste heat of the secondary steam after the vacuum belt dryer is dried, which is used to dry the pomace with superheated steam, thereby maximizing energy utilization and realizing the combined drying of juice and pomace, achieving a steam recovery rate of 85%, a drying system thermal efficiency of 70% to 85%, and a material utilization rate of 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of the juice-pomace vacuum-superheated steam closed-loop drying system.

[0025] Description of Reference Numerals

[0026] 1-steam generator, 2-first valve, 3-fan, 4-second valve, 5-third valve, 6-fourth valve, 7-fifth valve, 8-hot juice outlet pipe, 9-preheater outer jacket, 10-stirring paddle, 11-condensate outlet pipe, 12-cold juice inlet pipe, 13-juice preheater, 14-sixth valve, 15-juice delivery pump, 16-vacuum belt dryer, 17-first conveyor belt mechanism, 18-first vacuum pump, 19-cutting mechanism, 20-steam compressor, 21-the seventh valve, 22-the second vacuum pump, 23-the superheated steam belt dryer, 24-the second conveyor belt mechanism, 25-the second material receiving mechanism, 26-the eighth valve, 27-the water pump, 28-the cold water main valve, 29-the ninth valve, 30-the tenth valve, 31-the first shell and tube heat exchanger, 32-the eleventh valve, 33-the second conveying pump, 34-the twelfth valve, 35-the first material receiving mechanism, 36-the thirteenth valve, 37-the steam main valve, 38-the second shell and tube heat exchanger. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0028] A juice-pomace vacuum-superheated steam closed-loop circulation drying system comprises a juice preheater 13, a juice delivery pump 15, a steam generator 1, a vacuum belt dryer 16, a first vacuum pump 18, a steam compressor 20, a low-pressure superheated steam belt dryer 23, and a second vacuum pump 22.

[0029] The juice enters the preheater from the cold juice inlet pipe 12, and the hot juice outlet pipe 8 of the juice preheater 13 is connected to the material inlet of the vacuum belt dryer 16 through the juice delivery pump 15 and connected to the upper surface of the first conveyor belt mechanism 17; the first steam outlet pipeline of the steam generator 1 is connected to the outer jacket 9 of the preheater. The second steam outlet pipeline of the steam generator 1 is connected to the first steam inlet of the vacuum belt dryer 16. The secondary steam outlet of the vacuum belt dryer 16 is pressurized and heated by the first vacuum pump 18 and the steam compressor 20, and then transported to the low-pressure superheated steam belt dryer 23 through the eighth valve 26, and the pomace on the second conveyor belt mechanism 24 inside the low-pressure superheated steam belt dryer 23 is superheated steam dried. The low-pressure superheated steam outlet of the low-pressure superheated steam belt dryer 23 is connected to the outer jacket 9 of the preheater through the second vacuum pump 22 and the seventh valve 21, and the condensate outlet pipe 11 of the outer jacket 9 of the juice preheater is connected back to the cold water inlet of the steam generator 1; the material outlet of the vacuum belt dryer 16 is provided with a first material receiving mechanism 35, and the material outlet of the low-pressure superheated steam belt dryer 23 is provided with a second material receiving mechanism 25.

[0030] A three-layer conveyor belt is provided in the vacuum belt dryer 16. A first heating zone, a second heating zone, a third heating zone and a cooling zone are sequentially arranged at the bottom of the three-layer conveyor belt in the vacuum belt dryer 16 from the material inlet to the material outlet. The first heating zone, the second heating zone, the third heating zone and the cooling zone are all first heating plates, second heating plates, third heating plates and cooling plates with heating medium circulation cavities; the second steam outlet pipeline of the steam heater is connected to the first heating zone; the third steam outlet pipeline of the steam heater is connected to the second heating zone after passing through the first branch and the first shell and tube heat exchanger 31, and is connected to the third heating zone after passing through the second branch and the second shell and tube heat exchanger 38. The cooling zone is connected to a cold water source. The cold water generated in the first heating zone, the second heating zone and the third heating zone is transported back to the steam generator 1 through the second valve 4. The cold water generated in the first shell and tube heat exchanger 31 and the second shell and tube heat exchanger 28 is transported back to the cold water inlet of the steam generator 1 through the second delivery pump 33 and the first valve 2. The cold water in the cooling zone is returned to the factory for daily use.

[0031] When the system is working, the steam generator 1 is started, the steam main valve 37, the thirteenth valve 36, and the cold water main valve 28 are opened, and the steam generated by the steam generator 1 is transported by the fan 3 through the sixth valve 14 to the outer jacket 9 of the preheater to preheat the juice. A stirring paddle 10 is arranged inside the juice preheater 13, and the stirring paddle is controlled by an electric device, such as a servo motor, and is used to stir the juice to improve the temperature uniformity.

[0032] The third valve 5 is opened, and the condensed water in the outer jacket 9 of the preheater after preheating is passed into the steam generator 1 as the supplementary water of the steam generator; the fourth valve 6 is opened, and a part of the steam in the steam generator 1 is used as the heat source to dry the material. The eleventh valve 32 and the twelfth valve 34 are opened, and another part of the steam in the steam generator 1 is passed into the first shell and tube heat exchanger 31 and the second shell and tube heat exchanger 38. The ninth valve 29 and the tenth valve 30 are opened, and a part of the cold water is transported by the water pump 27 to the first shell and tube heat exchanger 31 and the second shell and tube heat exchanger 38 for heat exchange, and the other part is used to cool the dried material.

[0033] The fifth valve 7 is opened, and the material preheated by the preheater is transported to the vacuum belt dryer 16 through the juice delivery pump 15, and the material after drying is collected by the first material receiving mechanism 35. The pomace is transported to the superheated steam belt dryer 23 through the feed pipe, and is collected by the second material receiving mechanism 25 after drying.

[0034] The seventh valve 21 is opened and the thirteenth valve 36 is closed. The steam after drying is transported to the outer jacket 9 of the preheater through the pump 22, and the condensed water generated in the process is transported to the steam generator 1. The condensed water generated in the first shell and tube heat exchanger 31 and the second shell and tube heat exchanger 38 is also transported to the steam generator 1.

[0035] A material cut-off mechanism 19 is provided at the material outlet end of the vacuum belt dryer 16 to block the material on the conveyor belt in the vacuum belt dryer 16 to facilitate the collection of the product after drying.

[0036] A drying method using the juice-pomace vacuum-superheated steam closed-circuit drying system comprises the following steps:

[0037] 1) Juice preheating: Turn on the steam generator 1 and supply saturated steam to the outer jacket 9 of the preheater. After the saturated steam fills the outer jacket 9 of the preheater, the juice enters the preheater through the cold juice inlet pipe 12 and is stirred by the stirrer to be evenly heated. The temperature is preheated from room temperature to 40-45°C;

[0038] 2) Juice vacuum belt drying: The preheated juice is conveyed to the first conveyor belt mechanism 17 of the vacuum belt dryer 16 by the juice conveying pump 15, and passes through the first heating zone, the second heating zone, the third heating zone and the cooling zone in sequence, and the juice is gradually dried into dry powder. The obtained dry product is cut by the cutting mechanism 19 and the dry powder is collected by the first collecting device;

[0039] 3) Secondary steam recompression: A large amount of secondary superheated steam generated by the juice drying in the vacuum belt dryer 16 is pumped by the first vacuum pump 18 to the steam compressor 20, which compresses the low-pressure superheated steam of about 50°C to low-pressure superheated steam of about 70°C;

[0040] 4) Superheated steam belt drying of pomace: The compressed low-pressure superheated steam enters from the bottom of the superheated steam belt dryer 23 and serves as a heat source to heat and dry the pomace. The pomace is transported in the superheated steam belt dryer 23 by the second conveyor belt mechanism 23. After being evenly distributed, the superheated steam evenly heats the pomace. The dried product is collected by the second receiving mechanism 25.

[0041] 5) Recycling of superheated steam: The secondary low-pressure superheated steam generated during the pomace superheated steam belt drying process is pumped by the second vacuum pump 22 to the outer jacket 9 of the preheater as a heat source to heat the cold juice;

[0042] 6) Heating by steam generator 1: the saturated steam generated by steam generator 1 is supplied to the outer jacket 9 of the preheater through the first steam outlet at the initial stage of drying; the saturated steam generated by steam generator 1 is supplied to the first heating zone in the vacuum belt dryer 16 through the second steam outlet as a heat exchange medium; the saturated steam generated by steam generator 1 is supplied to the first shell and tube heat exchanger and the second shell and tube heat exchanger through the third steam outlet as a heat source to heat cold water to hot water of a certain temperature, and the obtained hot water of different temperatures is used as the heat exchange medium of the second heating zone and the third heating zone of the vacuum belt dryer 16;

[0043] 7) Water recycling process: the condensed water produced by the outer jacket 9 of the preheater in step 5), the condensed water produced by the first shell and tube heat exchanger and the second shell and tube heat exchanger are transported back to the steam generator 1 through pipelines as supplementary water, and are recycled after being heated to saturated steam.

[0044] Taking fresh blueberries as an example, the initial moisture content is about 90%. After squeezing the juice (blueberry juice yield is 70%), the blueberry juice and blueberry pomace are dried separately. The blueberry juice at room temperature T1 is preheated to T6 = 40°C by the preheater and then enters the vacuum belt dryer 16. After a short period of time after entering the vacuum belt dryer, the moisture content of the material drops to a certain value ω after a cooling process, and the viscosity of the material increases. Then, it passes through the first heating zone, the second heating zone, the third heating zone and the cooling zone in turn, and the obtained long strip dried product (final moisture content is 5%, temperature T2) is cut by the cutting mechanism 19 and collected by the collecting device. The energy provided by this part to the material to heat up and evaporate the water is

[0045] Q1=r w (ω-0.05)m1+m2C p2 T2-m1C p1 T1;

[0046] The secondary steam generated in the process is transported by the first vacuum pump 18 to the steam compressor 20 for compression to improve the energy quality. The secondary steam at about 50°C is compressed and heated to about 70°C for low-pressure superheated steam drying of blueberry pomace. The power consumption of this process is Q2=nP1t, and the initial energy of the secondary steam is

[0047] Q3=C p0 m3(T3-T0)-r w (m2-m1);

[0048] The blueberry pomace is fed into the superheated steam belt dryer 23 through the feeding device and dried to a final moisture content of 20%. The process includes heating of the material and evaporation of water. The strip product is finally cut by the cutting device and collected by the collecting device. The energy required for this process is Q4 = r w (0.9-0.2)m4+m5C p4 T5-m4C p3 T1; the secondary superheated steam generated in the process is pumped by the second vacuum pump 22 to the outer jacket 9 of the preheater to be used as a heating medium to preheat the concentrated blueberry juice, and the exchange heat is Q5 = C p5 m1T6-C p1 m1T1. The hot water generated after passing through the preheater is used as supplementary water for steam generator 1. At this time, the energy of the condensed water is Q6=m(h2-h1), where h1 and h2 are the enthalpy values ​​of superheated steam in different states. The secondary steam utilization rate is

[0049]

[0050] The utilization rate of secondary steam in the drying system is over 85%.

[0051] The heat energy in the drying system is provided by steam generator 1, and this part of energy is Q0 = P2t; the heat utilization rate of steam generator 1 is taken as the thermal efficiency of the drying system. In the system, the steam generator is used to heat cold water, accounting for 20%.

[0052]

[0053] Substituting corresponding parameters, the energy utilization rate of the drying system is obtained to be 65% to 80%.

[0054] The system process parameters are as follows:

[0055]

[0056]

[0057] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A juice-pomace vacuum-superheated steam closed-circuit drying system, characterized in that: The invention comprises a juice preheater (13), a juice delivery pump (15), a steam generator (1), a vacuum belt dryer (16), a first vacuum pump (18), a steam compressor (20), a low-pressure superheated steam belt dryer (23), and a second vacuum pump (22); the hot juice outlet pipe (8) of the juice preheater (13) is connected to the material inlet of the vacuum belt dryer (16) through the juice delivery pump (15) and is connected to the upper surface of the first conveyor belt mechanism (17); the first steam outlet pipeline of the steam generator (1) is connected to the outer jacket (9) of the preheater; the second steam outlet pipeline of the steam generator (1) is connected to the outer jacket (9) of the preheater; and the second steam outlet pipeline of the steam generator (1) is connected to the outer jacket (9) of the vacuum belt dryer (16). a first steam inlet; the secondary steam outlet of the vacuum belt dryer (16) is pressurized and heated by a first vacuum pump (18) and a steam compressor (20) and then transported to a low-pressure superheated steam belt dryer (23); the low-pressure superheated steam outlet of the low-pressure superheated steam belt dryer (23) is connected to the outer jacket (9) of the preheater via a second vacuum pump (22); the condensate outlet pipe (11) of the outer jacket (9) of the juice preheater is connected back to the cold water inlet of the steam generator (1); the material outlet of the vacuum belt dryer (16) is provided with a first material receiving mechanism (35), and the material outlet of the low-pressure superheated steam belt dryer (23) is provided with a second material receiving mechanism (25).

2. The juice-pomace vacuum-superheated steam closed-circuit drying system according to claim 1 is characterized by: The vacuum belt dryer (16) is provided with a three-layer conveyor belt. The bottom of the three-layer conveyor belt in the vacuum belt dryer (16) is provided with a first heating zone, a second heating zone, a third heating zone and a cooling zone in sequence from the material inlet to the material outlet. The first heating zone, the second heating zone, the third heating zone and the cooling zone are all first heating plates, second heating plates, third heating plates and cooling plates with heating medium circulation cavities. The second steam outlet pipeline of the steam generator (1) is connected to the first heating zone. The third steam outlet pipeline of the steam generator (1) is connected to the second heating zone via a first branch and a first shell-and-tube heat exchanger (31), and is connected to the third heating zone via a second branch and a second shell-and-tube heat exchanger (38). The cooling zone is connected to a cold water source. The cold water generated by the first heating zone, the second heating zone and the third heating zone is transported back to the steam generator (1). The cold water generated by the first shell-and-tube heat exchanger (31) and the second shell-and-tube heat exchanger (38) is transported back to the cold water inlet of the steam generator (1). The cold water in the cooling zone is returned to the daily water use of the factory.

3. The juice-pomace vacuum-superheated steam closed-circuit drying system according to claim 2 is characterized in that: A material cutting mechanism (19) is provided at the material outlet end of the vacuum belt dryer (16).

4. A drying method using the juice-pomace vacuum-superheated steam closed-circuit drying system as claimed in claim 3, characterized in that: The steps include: 1) Juice preheating: Turn on the steam generator (1) and supply saturated steam to the outer jacket (9) of the preheater. After the saturated steam fills the outer jacket (9) of the preheater, the juice enters the preheater through the cold juice inlet pipe (12) and is stirred by the stirrer so that the juice is evenly heated. The temperature is preheated from room temperature to 40-45°C. 2) Juice vacuum belt drying: the preheated juice is conveyed to the first conveyor belt mechanism (17) of the vacuum belt dryer (16) by the juice conveying pump (15), and passes through the first heating zone, the second heating zone, the third heating zone and the cooling zone in sequence, and the juice is gradually dried into dry powder. The obtained dry product is cut by the cutting mechanism (19) and the dry powder is collected by the first collecting device; 3) Secondary steam recompression: A large amount of secondary superheated steam generated by the juice drying in the vacuum belt dryer (16) is pumped by the first vacuum pump (18) to the steam compressor (20), and the low-pressure superheated steam at about 50°C is compressed to low-pressure superheated steam at about 70°C; 4) Superheated steam belt drying of pomace: compressed low-pressure superheated steam enters from the bottom of the superheated steam belt dryer (23) and serves as a heat source to heat and dry the pomace. The pomace is transported in the superheated steam belt dryer (23) by a second conveyor belt mechanism (24). After being evenly distributed, the superheated steam evenly heats the pomace. The dried product is collected by a second material receiving mechanism (25); 5) Recycling of superheated steam: the secondary low-pressure superheated steam generated during the pomace superheated steam belt drying process is pumped by the second vacuum pump (22) to the outer jacket (9) of the preheater to serve as a heat source for heating the cold juice; 6) Steam generator (1) heat supply: the saturated steam generated by the steam generator (1) is supplied to the outer jacket (9) of the preheater through the first steam outlet at the initial stage of drying; the saturated steam generated by the steam generator (1) is supplied to the first heating zone in the vacuum belt dryer (16) as a heat exchange medium through the second steam outlet; the saturated steam generated by the steam generator (1) is supplied to the first shell and tube heat exchanger and the second shell and tube heat exchanger (38) through the third steam outlet to provide saturated steam as a heat source to heat cold water to hot water of a certain temperature, and the obtained hot water of different temperatures is used as the heat exchange medium of the second heating zone and the third heating zone of the vacuum belt dryer (16); 7) Water recycling process: the condensed water generated by the outer jacket (9) of the preheater in step 5) and the cold water generated by the first heating zone, the second heating zone and the third heating zone are all transported back to the steam generator, and the condensed water generated by the first shell and tube heat exchanger (31) and the second shell and tube heat exchanger (38) are transported back to the steam generator (1) through a pipeline as supplementary water, and are recycled after being heated to saturated steam.

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