Common problems and solutions of vacuum freeze dryer

With the development of freeze-drying technology, vacuum freeze-drying machine is widely used in biology, medicine, preparation of nanostructured materials and other fields. Due to the working characteristics of vacuum freeze dryer, vacuum freeze dryer often works beyond its limit, this leads to some faults in the refrigeration system, which is the core component of the vacuum freeze dryer. Refrigerator are composed of compressor, evaporator, condenser, expansion valve, liquid-vapor separator, oil separator and other parts. In order to reduce the occurrence of faults in the refrigeration system of vacuum freeze dryer, it is necessary to understand some common faults and master the solutions to these faults, the common problems in the refrigeration system of vacuum freeze dryer are analyzed in detail, and the daily maintenance and maintenance of the refrigeration system of vacuum freeze dryer are summarized.

Several common faults of refrigeration system of vacuum freeze dryer include: high pressure alarm, motor overload of compressor, high motor temperature, alarm of oil pressure difference, the alarm of water pressure and the actual effect of expansion valve regulation are analyzed, and the causes and related solutions of faults in these aspects are analyzed.

1. For the occurrence of high-pressure alarm, there are roughly the following reasons: the water quantity in the water condenser is insufficient or the water temperature is too high; Some scale is formed inside the water condenser, which reduces the heat conversion efficiency; when the compressor is working, the low-pressure pipeline is broken, which makes the air enter the refrigeration pipeline; The valve of the refrigeration pipeline is not fully opened, or the exhaust pipeline is blocked, which causes the unsmooth exhaust; too much use of refrigerator leads to excessive exhaust pressure.

The solution is: reduce the water temperature or increase the flow; Clean the water condenser; Make the refrigeration pipeline simple. If the operation cannot be carried out in the working state, the stop valve above the water condenser can be opened first, release part of the air from the water condenser; That is, the valve on the compressor pipeline needs to be opened to the maximum;A part of the refrigerator needs to be released.

2. For the occurrence of motor overload of the compressor, the reason may be: there are sundries in the piston cylinder, which makes the piston not smooth, and the situation of holding the shaft and closing the cylinder occurs; The thermal load of the compressor is overloaded, the reason may be caused after steam sterilization and other operations; The relay of thermal overload is not reset in time.

The solution is: clean up the internal residue of the compressor in time; Cool the compressor to the allowable temperature in time; Reset the relay in time.

3. For the occurrence of high motor temperature, the reason may be that the refrigerator is insufficient at ventilation, resulting in insufficient cooling of the motor; The refrigerator is insufficient or lacking; The three-phase power supply of the compressor is unstable; there is a problem with the thermal protection module of the compressor; The liquid supply pipeline is blocked.

The solution is: Restart the switch of the compressor; Replenish the refrigerant in time; Provide the power supply of the compressor according to the requirements; Dredge the blocked parts in time; Replace the template if necessary.

4. For the alarm situation of the oil pressure difference, the reason may be that the relay of the oil pressure difference is not reset in time; If the refrigeration oil is yellow or black, the refrigeration oil may deteriorate, causing the filter to be blocked; in addition, there is a problem with oil return, which makes the oil in the crankcase of the compressor not reach and the oil pump cannot absorb oil.

The solution is: manually reset; Clean the filter and replace the refrigeration oil; Tap the oil separator with hard objects. If it doesn't work, replace the separator.

5. For the alarm situation of water pressure, the reason may be that the supply of cooling water is insufficient; Or the relay of water pressure fails.

The solution is to increase the external water supply pressure; Check the pressure relay.

6. In the case of expansion valve adjustment failure, the reason may be that the internal adjustment gear is pulled due to long-term force; Expansion valve is blocked, this causes the pressure of the low pressure gauge of the compressor to be too low.

The solution is: tap the gear teeth to make the gear teeth parallel to the internal plane; Disassemble the expansion hair and clean it again; Check the pipeline and filter or valve to open.