Preparation before operation of pressure swing vacuum drying equipment:

1) Clean the drying tank and keep the tank clean.

2) Carefully check the vacuum pump according to the operation manual of the vacuum pump. Check whether the pump oil of the vacuum pump is sufficient and whether there is serious emulsification through the oil standard. If the pump oil is insufficient, add the correct type of vacuum pump oil through the oil filling port of the pump. If the pump oil has been seriously emulsified, it must be replaced, otherwise the vacuum will be seriously affected.

3) Check whether the heat transfer oil circulation pipeline is unblocked and whether the front and rear stop valves of the heat transfer oil circulation pump are opened.

4) Check whether the oil level in the heat transfer oil expansion tank is normal. Observe the liquid level gauge and keep it between 20-25cm in cold state.

5) Check whether there is condensate in the condenser and effusion tank, and drain it if necessary. Whether the pressure of vacuum pipeline is normal pressure, not to restore to normal pressure.

6) Check whether the power supply, water source and air source required for the operation of the equipment are normal.

7) Check whether the indication of each instrument is normal.

In the pre dehydration stage of pressure swing drying, only the air in the tank is heated. At this time, the tank is connected with the outside world. The dry hot air quickly changes the original temperature field. Due to the relative movement of the air flow, the heat exchange is strengthened, the body temperature increases evenly, and the temperature gradient between the coil and the iron core becomes smaller. When the furnace temperature reaches the set value, it can be considered that the pre dehydration stage is over. The length of pre dehydration depends on the heat absorbed by the body and the heat dissipation area of the radiator. The specific action process is as follows:

When the vent valve is opened, the heat transfer oil pump and heater are automatically opened respectively. The heat transfer oil starts to circulate and heat the vacuum tank. The body is heated by radiation through the heating exhaust pipe in the vacuum tank and by gas convection. When the temperature in the tank reaches 60 ~ 65 ℃ (this temperature depends on the process requirements) at 15 ~ 20 ℃ / h, the pre dehydration stage ends.

When the iron core and coil reach a certain temperature, the heat absorbed by the coil has decreased significantly, and a large amount of heat energy is absorbed by the iron core with large heat capacity. At this time, turn on the vacuum pump to make the tank have a certain vacuum degree, and the water on the surface and shallow layer begins to evaporate. Increase the vacuum degree intermittently, so that part of the evaporated water is drawn out of the tank, and the other part participates in heat exchange as a heat transfer medium.