The temperature adjustment problem of the freeze dryer can be better solved without setting the temperature adjustment unit:
1. On the premise that the cooling capacity of the refrigeration compressor is surplus, a refrigeration branch that can provide appropriate cooling capacity is added next to the refrigeration system pipeline that supplies cooling to the front box of the freeze dryer to meet the cooling capacity during temperature adjustment;
2. At the same time, since the refrigeration compressor is supplying cooling to two evaporators with different evaporating temperatures during temperature adjustment, the difference in working conditions may have a greater impact on the refrigeration compressor due to the lag of the expansion valve control.
It will lead to the hydraulic shock of the refrigeration compressor and cause failure, which requires a good grasp of the control of the return steam pressure. Now the technicians have added a solenoid valve on the return steam line of the front box evaporator, and the solenoid valve is controlled by the pressure controller.
The monitoring of the pressure difference between the front and rear controls the opening or closing of the valve to reduce the load impact during temperature adjustment and ensure the smooth operation of the compressor;
3. In order to prevent the pressure in the front box evaporator from rising due to the closing of the electromagnetic valve, and the temperature adjustment effect cannot be guaranteed, the technicians added a steam return branch pipe to the return steam pipeline before the electromagnetic valve, which is connected to the The suction pipe of the secondary compression of the refrigeration compressor, through the practice on multiple freeze dryers, the results have proved that this treatment plan is feasible.
Therefore, the capillary temperature adjustment commonly used now causes unsatisfactory temperature adjustment effect and load impact on the compressor.
The leakage of fluorine in the freeze dryer must first find the leakage point. The specific operation of the leakage point is as follows:
1. First, use the visual method to open the machine box of the freeze dryer to observe the inside of the machine. Since the refrigerant is running, there will be compressor lubricating oil mixed in it. If there is a leakage of Freon, the lubricating oil will be taken out, then carefully observe the machine. Inside, if there is a flaky oil stain, it is likely to be a leak.
2. Then check whether the capillary copper tubes inside the freeze dryer, that is, those thin copper tubes and process tubes below 6 mm, are broken. After passing the basic inspection above, mark the areas in doubt.
3. Then it is necessary to confirm the leak point by adding a certain pressure of inert gas. Nitrogen is used to maintain the pressure under conditions. There is no nitrogen available for gaseous Freon in the adsorption dryer. It is strictly forbidden to use oxygen to maintain the pressure and check for leaks.