Solution to the temperature adjustment problem of freeze dryer
During the freeze-drying process of the freeze dryer, the temperature pre-freezing of the liquid articles and the subsequent sublimation of the moisture in the solid matter need to control the temperature within a certain range of the process requirements, which requires the freeze dryer to have a certain precision of temperature regulation. Features. How to better solve the temperature regulation problem of the freeze dryer without setting the temperature control unit, the specific scheme is as follows:
1. In the premise of the refrigeration capacity of the refrigeration compressor, a refrigeration branch that can provide appropriate cooling capacity is provided next to the refrigeration system piping for cooling the front of the freeze dryer to meet the cooling demand during temperature adjustment;
2. At the same time, due to the temperature adjustment, the refrigeration compressor is supplying cooling to two evaporators with different evaporation temperatures. The difference in working conditions may cause a large impact on the refrigeration compressor due to the hysteresis of the expansion valve control. In severe cases, It will cause the liquid pressure of the refrigeration compressor to cause a failure, which requires a good grasp of the control of the return steam pressure. The technicians now add an electromagnetic valve to the steam return line of the front tank evaporator, and the electromagnetic valve is passed through the pressure controller. The monitoring of the differential pressure before and after to control the opening or closing of the valve reduces the load shock during the temperature adjustment to ensure the smooth operation of the compressor;
3. In order to prevent the pressure in the front tank evaporator from rising due to the closing of the electromagnetic valve, the temperature adjustment effect is not guaranteed, and the technician adds a steam return pipe to the steam return line in front of the electromagnetic valve, and is connected to The two-stage compressed suction pipe of the refrigeration compressor proves that this treatment scheme is feasible through the practice on multiple freeze dryers. It can avoid the increase of the cost of adding the temperature control unit and solve the present problem. The commonly used capillary temperature regulation results in an unsatisfactory temperature regulation effect and a load shock to the compressor.