Vacuum Freeze Dryer Is Required To Have A Certain Precision Temperature Adjustment Function
During the lyophilization process, 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 vacuum freeze dryer to have a certain precision temperature adjustment function. Under the premise of not setting the temperature control unit, the temperature regulation problem of the vacuum freeze dryer is better solved. The specific scheme is as follows:
1. In order to meet the cooling capacity of the refrigeration compressor, add a cooling branch that can provide appropriate cooling capacity to the refrigeration system before the vacuum freeze dryer to meet the cooling capacity of the 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, and ensures the smooth operation of the compressor of the vacuum freeze dryer;
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 vacuum freeze dryer technician adds a steam return to the steam return line in front of the electromagnetic valve. The branch pipe, connected to the secondary compressed suction pipe of the refrigeration compressor, has been proved to be practical by the practice on multiple vacuum freeze dryers, which can avoid the increase of the cost of adding the temperature control unit. Moreover, the capillary temperature adjustment which is generally used nowadays has caused the temperature adjustment effect to be unsatisfactory and the load impact on the compressor.
