Pilot freeze dryers are used in the fields of medicine, biological products, food processing and health food. In the freeze-drying process, the temperature of the liquid items is pre-frozen and the subsequent sublimation of the moisture in the solid items needs to be controlled within a certain range of process requirements, which requires the pilot Freeze Dryer to have a certain temperature adjustment function .
　　Under the premise of not setting a temperature adjustment unit, how to better solve the temperature adjustment problem of the pilot freeze dryer, the specific plan is as follows:
　　In order to meet the cold demand during temperature adjustment, a cooling branch that can provide appropriate cold capacity is added next to the refrigeration system pipeline that supplies cold water to the front box of the pilot freeze dryer under the premise of surplus cold capacity of the refrigeration compressor. ;
　　At the same time, when the temperature is adjusted, the refrigeration compressor is cooling two evaporators with different evaporating temperatures. The difference in operating conditions may have a greater impact on the refrigeration compressor due to the lag of the expansion valve control. In severe cases, it may cause The liquid compressor of the refrigeration compressor causes a failure, which requires a good grasp of the control of the return steam pressure. Now the technician has added an electromagnetic valve on the return steam line of the front tank evaporator, and the pressure controller is used to press the electromagnetic valve back and forth. Poor monitoring to control the opening or closing of the valve to reduce the load shock during temperature adjustment and ensure the smooth operation of the compressor;
　　In order to prevent the pressure in the front tank evaporator from being increased due to the closing of the solenoid valve, the temperature adjustment effect cannot be guaranteed, and the technician added a steam return branch pipe to the steam return line in front of the solenoid valve, which is connected to the refrigeration compression The second-stage compressed suction pipe of the machine, through the practice on multiple freeze dryers, the result proves that this treatment scheme is practical and feasible. It can not only avoid the increase in the cost of adding a temperature regulating unit, but also solve the current widespread adoption. The capillary temperature adjustment caused the unsatisfactory temperature adjustment effect and impact on the load of the compressor.
　　Pilot freeze dryer adopts this scheme to adjust the temperature, which not only can reduce the cost, but also solve the situation where the adjustment effect of other schemes is not ideal.