Novel freeze dryer using residual heat to recover defrosting water and operation method thereof

Abstract

The invention discloses a novel freeze dryer using residual heat to recover defrosting water and an operation method thereof. A refrigeration system of the freeze dryer comprises a refrigeration compressor, a primary condenser, a secondary condenser, a throttle valve, an evaporator, a cold trap, a refrigerating coil, a drying closet, a solenoid valve, a cold oil tank, a hot oil tank, a cold tank pump, a hot tank pump, a three-way valve, and a tank trap valve; a cooling capacity and heat collection system comprises a heat collection system composed of the primary condenser, the hot oil tank andthe hot tank pump, and a cooling capacity collection system composed of the evaporator, the cold tank pump and the cold oil tank; a vacuumization system comprises the cold trap, the tank trap valve and a vacuum pump; and a defrosting system comprises an electrical heater, an oil pump, a water collection tank, the three-way valve, a defrosting coil, and a water drawing valve. The operation methodcomprises four stages including prefreezing, sublimation drying, desorption drying, and defrosting. According to the novel freeze dryer using residual heat to recover defrosting water and the operation method thereof, system energy consumption is reduced, energy saving effect is good, a system is simplified, equipment malfunction rate is lowered, service life is improved, the system is safe, operation is more convenient, and feasibility is better.

Description

technical field [0001] The invention relates to a novel freeze-dryer which utilizes residual temperature to recover defrosting water and an operation method thereof, belonging to the technical field of refrigeration. Background technique [0002] Vacuum freeze-drying technology is to cool the wet material below the eutectic point temperature, so that the water and water vapor inside the material and inside the freeze-drying box become solid ice, and then use the vacuum system to create a vacuum condition for the freeze-drying box. Direct heating in the environment makes the ice sublime into water vapor, and the water is condensed and collected in the cold trap, so as to achieve the purpose of drying the material. There are mainly two problems in existing freeze-drying equipment. One is that when drying a large amount of food such as seafood or fruits and vegetables, through the three stages of pre-freezing, sublimation drying and analytical drying, a large amount of free wa...

AI Technical Summary

Problems solved by technology

One is that when drying a large amount of food such as seafood or fruits and vegetables, through the three stages of pre-freezing, sublimation drying and analytical drying, a large amount of free water and bound water will become water vapor through solidification and sublimation, and then be cooled. Trap capture, most of the existing freeze-drying equipment captures and solidifies water vapor directly through the cold trap in the vacuum system, which is not properly collected and utilized, resulting in a waste of resources, especially for large-scale freeze-drying equipment, the cold trap A large amount of water will be captured inside, and the water stored in the materials to be dried, especially fruits and vegetables, has good health value and can be recycled

Second, the existing natural defrosting method takes a long time, and the freeze-drying operation of a new batch of materials can only be started after the defrosting is completed, which affects the batch work efficiency of freeze-drying

Third, during the freeze-drying process, the pre-freezing stage needs to be reduced to and kept at a very low temperature, which requires more energy. The heat in the freeze-drying box needs to be taken out and released, and refrigeration is required in the sublimation and desorption drying stages. It works intermittently with heating to maintain a constant drying and dehydration temperature. During this period, heat needs to be taken out and added repeatedly. On the one hand, the refrigeration cycle is used to cool down, and the heat in the freeze-drying box is discharged at the same time. On the other hand, electric heating is used to raise the temperature. A lot of energy is wasted, and this start-stop control method has low temperature control accuracy and large temperature fluctuations, which affects the quality of dry products, and also leads to frequent actions of related temperature control adjustment and executive components, increased failures, and shortened service life

Fourth, the set temperature in the analytical drying stage of the existing freeze-drying equipment is usually not high, which cannot meet the analytical drying requirements of different materials and increase the drying speed

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