CN106482454A - A kind of vacuum freeze-drying system and its drying meanss - Google Patents

Abstract

The invention discloses a vacuum freeze-drying system and a drying method thereof. The drying system includes a freeze-drying box, a water vapor condenser, a vacuum system, a mechanical refrigeration system and a thermoelectric system. The mechanical refrigeration system consists of a compressor, a liquid storage device, a condenser The freeze-drying box is connected with the water vapor condenser through the gate valve used to control on-off, and the vacuum system is connected with the water vapor condenser to maintain the vacuum degree of the system. The mechanical refrigeration system provides cooling capacity for the freeze-drying box and the water vapor condenser. The freeze-drying box is equipped with a material partition. The thermoelectric system is composed of the control end, the hot end of the thermoelectric system and the cold end of the thermoelectric system. The hot end of the thermoelectric system is separated from the material. The plates are connected, and the cold end of the thermoelectric system is connected to the water vapor condenser. The invention improves the energy utilization rate of the freeze-drying system, the temperature distribution uniformity of the heating partition, the temperature control precision of the heating partition and the effect and quality of the freeze-dried product.

Description

A vacuum freeze-drying system and drying method thereof

technical field

The invention belongs to the field of freeze-drying, and more specifically relates to a vacuum freeze-drying system and a drying method thereof.

Background technique

The process of vacuum freeze-drying is generally divided into pre-freezing, first-stage drying and second-stage drying. Pre-freezing solidifies the free water in the material to prevent irreversible occurrences such as foaming, concentration, and solute migration under vacuum. The products have the same form. In this process, the temperature of the freeze-drying box and the water vapor condenser is lowered to a sufficiently low temperature. The cooling of the material can occur in the freeze-drying box, or it can be completed before entering the drying box; the first stage of drying uses The ice crystal sublimates into water vapor and overflows the material to dehydrate and dry the material. At this stage, the material in the freeze-drying box must be properly heated, and the water vapor condenser must be kept at a very low temperature to allow the material to overflow and condense the water vapor. This process can remove the material from the material. Ninety percent of water; the second stage of drying is also called analytical drying, because after the first stage of drying, a part of water is still adsorbed on the capillary and polar genes of the dry material, due to its high adsorption energy, it is necessary to provide more High energy, the temperature of the heated material should be higher than that of the first stage of drying, but do not burn the material. In the first and second stages of the traditional freeze dryer, the material in the drying box is generally heated by electric heating, which requires additional heating. Circulation system, for the indirect heating system, it is necessary to increase the auxiliary circulation system, which increases the complexity of the freeze-drying system, and the efficiency of pure electric heating is low, and the energy waste is serious; in the first and second stages of drying, the freeze-drying box needs to be heated , and the water vapor condenser needs refrigeration to capture the water vapor from the drying box. After drying, the water vapor condenser needs to be heated to melt the ice and discharge it. The thermoelectric system has its unique advantages, and its temperature control accuracy is high. It can be changed by changing The method of switching the cooling end and the heating end by the method of the current direction has developed rapidly in recent years.

Contents of the invention

In order to improve the energy utilization rate of the freeze-drying system, simplify the heating system, and improve the temperature distribution uniformity of the heating partition, this patent provides a new type of freeze-drying system and its drying method, which effectively simplifies the system structure and improves the temperature of the heating partition Control precision to improve the effect and quality of freeze-dried products.

The purpose of the present invention is achieved through the following technical solutions:

A vacuum freeze-drying system includes a freeze-drying box, a water vapor condenser, a vacuum system, a mechanical refrigeration system and a thermoelectric system, and the mechanical refrigeration system consists of a compressor, a liquid receiver, a condenser, an intercooler, and a solenoid valve , a throttling valve and a gas-liquid separator, the freeze-drying box is connected with the water vapor condenser through a gate valve used to control on-off, the vacuum system is connected with the water vapor condenser to maintain the vacuum degree of the system, the mechanical The refrigeration system provides cooling capacity for the freeze-drying box and the water vapor condenser. The freeze-drying box is provided with a material partition. The thermoelectric system is composed of a control end, a thermoelectric system hot end and a thermoelectric system cold end. The thermoelectric system hot end and The material partitions are connected, and the cold end of the thermoelectric system is connected with a water vapor condenser.

A temperature sensor is arranged on the material separator, and the temperature sensor is electrically connected to the control terminal.

The precise control of the freeze-drying temperature of the material can be realized through the thermoelectric system and the temperature sensor.

The electromagnetic valve and the throttle valve are respectively provided with two correspondingly.

A drying method of a vacuum freeze-drying system, comprising the following steps:

(1) The material after preliminary cleaning is placed on the material partition in the freeze-drying box;

(2) Turn on the compressor, electromagnetic valve and throttle valve of the mechanical refrigeration system to cool the freeze-drying box and the water vapor condenser, control the material temperature to be 5-10°C lower than its eutectic point temperature, and complete the material pre-freezing process;

(3) Open the vacuum system and the gate valve, so that the vacuum degree in the freeze-drying box and the water vapor condenser is maintained within 100 Pa and lasts for 30 minutes;

(4) Close the solenoid valve, stop cooling the freeze-drying box, and turn on the thermoelectric system. The hot end of the thermoelectric system heats the material, and at the same time, the cold end of the thermoelectric system cools the water vapor condenser, and the heating temperature is controlled to be lower than the collapse temperature of the material. Complete the first and second stages of drying;

(5) Close the gate valve, control the thermoelectric system to reverse the current, cool down the freeze-drying box, and take out the dried materials. At the same time, the hot end of the thermoelectric system heats the water vapor condenser to melt the condensed ice and discharge the water vapor condenser to complete the drying process. .

Compared with the prior art, the beneficial effects brought by the technical solution of the present invention are:

1. It can realize the continuous work of freeze-drying of multiple batches of materials, and use the hot end and cold end of the thermoelectric system to realize the conversion of refrigeration and heating of the freeze-drying box and the water vapor condenser according to different working conditions.

2. The moisture in the material in the freeze drying box evaporates, absorbs heat, and solidifies in the water vapor condenser to release heat. The hot end of the thermoelectric system is in contact with the material, and the cold end of the thermoelectric system is in contact with the water vapor condenser. This is equivalent to releasing the water vapor from the condenser. The heat is transferred to the freeze drying box through the thermoelectric system to heat the material, and the heat of sublimation and heat of condensation cancel each other out, thereby reducing energy consumption.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention.

Reference signs: 1-compressor, 2-water vapor condenser, 3-vacuum system, 4-freeze drying oven, 5a-first throttle valve, 5b-second throttle valve, 6a-first electromagnetic valve, 6b -Second solenoid valve, 7-intercooler, 8-gas-liquid separator, 9-condenser, 10-liquid receiver, 11-cold end of thermoelectric system, 12-thermoelectric system, 13-hot end of thermoelectric system, 14 -Gate valve, 15-Material separator, 16-Temperature sensor

detailed description

Below in conjunction with accompanying drawing, the present invention will be further described:

As shown in Figure 1, a kind of vacuum freeze-drying system comprises freeze-drying box 4, water vapor condenser 2, vacuum system 3, mechanical refrigeration system and thermoelectric system 12, and mechanical refrigeration system consists of compressor 1, liquid accumulator 10 , condenser 9, intercooler 7, first solenoid valve 6a, second solenoid valve 6b, first throttle valve 5a, second throttle valve 5b and gas-liquid separator 8, freeze-drying box 4 and water vapor condenser 2 is connected and controlled by the gate valve 14, and the vacuum system 3 is connected with the water vapor condenser 2 to maintain the vacuum degree of the system; A material partition 15 is provided, and the thermoelectric system 12 is composed of a control end, a thermoelectric system hot end 13 and a thermoelectric system cold end 11, the thermoelectric system hot end 13 is connected to the material partition 15, and the thermoelectric system cold end 11 and its fins are connected with water vapor The condenser 2 is connected; the material partition 15 is provided with a temperature sensor 16 to measure the temperature of the material, and the temperature sensor 16 is connected with the control terminal circuit signal of the thermoelectric system 12, and the freeze-drying temperature of the material can be realized through the thermoelectric system 12 and the temperature sensor 16. precise control.

The control terminal of the thermoelectric system 12 can start and stop the system, and the direction of the current in the thermoelectric system 12 can realize different working conditions according to the different working stages of the freeze-drying box 4 .

The drying method of the vacuum freeze-drying system of the present invention comprises the following steps:

In the first step, the material to be freeze-dried after preliminary cleaning is placed on the material partition 15 in the freeze-drying box 4;

In the second step, open the mechanical refrigeration system order compressor 1, the first solenoid valve 6a, the second solenoid valve 6b, the first throttle valve 5a and the second throttle valve 5b, and carry out the freeze-drying box 4 and the water vapor condenser 2 Cooling, control the temperature of the frozen material to be 5-10°C lower than its eutectic point temperature, and complete the material pre-freezing process;

The third step is to open the vacuum system 3 and the gate valve 14, so that the vacuum degree in the freeze-drying box 4 and the water vapor condenser 2 is maintained within 100 Pa and maintained for 30 minutes;

The fourth step is to close the second electromagnetic valve 6b, stop the refrigeration of the freeze-drying box 4, and open the thermoelectric system 12, the hot end 13 of the thermoelectric system heats the material, and the cold end 11 of the thermoelectric system refrigerates the water vapor condenser 2 to control the heating The temperature is lower than the collapse temperature of the material, and the first and second stages of drying are completed;

The fifth step is to close the gate valve 14, control the thermoelectric system 12 to reverse the current, cool down the freeze drying box 4, and take out the dried materials. At the same time, the hot end 13 of the thermoelectric system heats the water vapor condenser 2 to melt the condensed ice and discharge water vapor Condenser 2.

For multi-batch material processing, after taking out the dried materials in the fifth step, put the next batch of materials to be processed, and use the cooling capacity generated by thermoelectric refrigeration and mechanical refrigeration to pre-freeze the materials together. Turn off the thermoelectric system and repeat steps 3, 4, and 5.

The present invention is not limited to the embodiments described above. The above description of specific embodiments is intended to describe and illustrate the technical solution of the present invention, and the above specific embodiments are only illustrative and not restrictive. Without departing from the gist of the present invention and the scope protected by the claims, those skilled in the art can also make many specific changes under the inspiration of the present invention, and these all belong to the protection scope of the present invention.

Claims (5)

1. A vacuum freeze-drying system, characterized in that, comprises a freeze-drying box, a water vapor condenser, a vacuum system, a mechanical refrigeration system and a thermoelectric system, and the mechanical refrigeration system consists of a compressor, a liquid accumulator, a condenser, It consists of an intercooler, solenoid valve, throttle valve and gas-liquid separator. The freeze-drying box is connected to the water vapor condenser through a gate valve for controlling on-off. The vacuum system is connected to the water vapor condenser to maintain the vacuum of the system. The mechanical refrigeration system provides cooling capacity for the freeze-drying box and the water vapor condenser. The freeze-drying box is provided with material partitions. The thermoelectric system is composed of a control end, a thermoelectric system hot end and a thermoelectric system cold end. The hot end of the thermoelectric system is connected to the material separator, and the cold end of the thermoelectric system is connected to the water vapor condenser. 2 . A vacuum freeze-drying system according to claim 1 , wherein a temperature sensor is arranged on the material separator, and the temperature sensor is electrically connected to the control terminal. 3 . 3. A vacuum freeze-drying system according to claim 2, characterized in that the precise control of the freeze-drying temperature of the material can be realized through a thermoelectric system and a temperature sensor. 4 . A vacuum freeze-drying system according to claim 1 , wherein two solenoid valves and two throttle valves are correspondingly provided. 5. the drying method of a kind of vacuum freeze-drying system according to claim 1, is characterized in that, comprises the following steps: (1) The material after preliminary cleaning is placed on the material partition in the freeze-drying box; (2) Turn on the compressor, electromagnetic valve and throttle valve of the mechanical refrigeration system to cool the freeze-drying box and the water vapor condenser, control the material temperature to be 5-10°C lower than its eutectic point temperature, and complete the material pre-freezing process; (3) Open the vacuum system and the gate valve, so that the vacuum degree in the freeze-drying box and the water vapor condenser is maintained within 100 Pa and lasts for 30 minutes; (4) Close the solenoid valve, stop cooling the freeze-drying box, and turn on the thermoelectric system. The hot end of the thermoelectric system heats the material, and at the same time, the cold end of the thermoelectric system cools the water vapor condenser, and the heating temperature is controlled to be lower than the collapse temperature of the material. Complete the first and second stages of drying; (5) Close the gate valve, control the thermoelectric system to reverse the current, cool down the freeze-drying box, and take out the dried materials. At the same time, the hot end of the thermoelectric system heats the water vapor condenser to melt the condensed ice and discharge the water vapor condenser to complete the drying process. .