Composition of vacuum freeze dryer (Part 1/2)
It is usually composed of six parts: drying bin, evaporator (water catcher), heating system, vacuum system, condensing system and electrical control system.
1. Drying Bin
It is a closed container that integrates the functions of vacuum and heating and drying. The sublimation and drying process of the material is completed in the drying warehouse. The material is placed in a stainless steel tray on a shelf in the drying room. Each layer of shelves has a probe for measuring the temperature of the material, which is used to monitor the temperature of the material during the entire lyophilization process.
2. Evaporator (water catcher)
It is a closed device for condensing and sublimating water vapor. It is usually located at the back of the drying chamber. There is a large area of metal adsorption surface inside. The water vapor sublimated from the drying chamber material can be condensed and adsorbed on its metal surface. The temperature can reach -45 ℃ ~ -65 ℃. The shape of the condenser is a cylinder made of stainless steel or iron. The inner plate is equipped with condenser tubes, which are connected to the refrigeration unit to form a refrigeration cycle system.
3. Heating system
The function of the lyophilizer heating system is to heat the materials in the drying bin, so that the materials are continuously sublimated by heat, so as to meet the specified moisture content requirements. The heating methods of the lyophilizer heating system are mainly divided into contact heating and radiation heating.
In contact heating, the circulating medium heating method is used. When the heating system is working, the circulating liquid is first heated. The liquid temperature is automatically controlled by the temperature selected by the tank control regulator. After the pipeline pump is turned on, the circulating liquid is sent to the shelf in the drying box, the shelf is heated, and then returned to the liquid tank for heating cycle.
In radiant heating, we usually use steam heating. When the circulating medium is silicone oil, the maximum temperature of the separator can reach + 120 ° C.