New vacuum drying equipment with variable pressure method

Pressure conversion vacuum drying equipment is an ideal equipment for oil-paper insulated power equipment such as power transformers with voltage 220 kV and 110 kV and less than 500 kv. Compared with traditional hot-air cycle drying, ordinary vacuum drying and low-frequency drying equipment, it can shorten the processing time by about 1/3 and save energy. The source consumption decreased by 30%-50%, and the moisture content of the insulation material after treatment reached the minimum of 5ppm. Its equipment investment is only 25%-45% of kerosene vapor phase drying equipment. It is the first choice of drying equipment for transformer manufacturers.

Working Principle: By means of vacuum, increase the saturated vapor pressure of water in the environment where the coil insulation material is located, make it easier to evaporate from the insulation paper. During this period, continuously heat it, raise the temperature, to ensure the gasification energy of water, so that water is easier to discharge.

Characteristics: ordinary heating and drying starts from the surface and gradually reaches the inside of the insulation material. Due to the rapid surface drying, the outer insulation paper capillary shrinkage, making it difficult to evaporate the internal moisture, prolonging the drying time. The pressure swing method is intermittent exhaust in the drying process, making the evaporated steam and hot air circulate in the tank together. Because the heat capacity of water is much larger than that of air, the heating speed is faster, and the diffusion of water vapor is strong, and the temperature difference inside and outside the insulation material is relatively small. In addition, in order to shorten the drying time, the heating temperature is often set very high, which is easy to make the coil surface insulation paper brittle cracking, product quality problems. However, the heat source temperature of the pressure swing drying equipment will not exceed 115-120 degrees C, and the core temperature will be controlled at 80 degrees C. Therefore, the drying products can not have the above problems. Because of this advantage, pressure-swing drying equipment can also be used for drying plastic parts and other high-temperature resistant products.

Equipment composition:

1. Vacuum drying tank: according to the use of two kinds of circular and rectangular, circular generally manual door locking, rectangular electric door hydraulic locking, heating pipe distribution in the tank. It is equipped with carriage trolley, which is used for transformer in and out of the tank. In order to make it convenient to sink the tank into the part below the ground, the trolley track and the ground level can be ensured. Users can also configure their own hovercraft.

2. Trolley system: Load trolley and drive two parts, trolley for low-speed operation, divided into manual and automatic two. The power of the automatic trolley can be divided into two forms: workshop driving and distribution drive.

3. Vacuum system: According to the requirements of the use of two or three vacuum, in order to prevent the loss of steam to the pump, the system is equipped with condenser.

4. Heating system: heat conducting oil is generally used as heat transfer medium, heat conducting oil is heated by electric heater, forced circulation is carried out by high-temperature pump, and heat is dissipated by exhaust pipe in vacuum tank. The system is equipped with temperature controller and PID adjustment. The accuracy of temperature control can reach 1 degree C. The system can also be controlled by steam heating and pneumatic membrane regulator.

5. Condensation system: It is mainly used to condense the moisture evaporated from the dried object and protect the effective operation of the vacuum pump. Generally, small equipment is cooled by water, and large equipment is equipped with industrial refrigerators.

6. Pneumatic system: Compressed air source, control valve, pressure detection system, etc., used for the control of vacuum, material valves.

7. cooling water system: it is mainly used for cooling some vacuum pumps and condensers.

8. hydraulic system: lock for rectangle tank door, also used for upturn of tank door. When the hovercraft is configured, it is used to turn over the slab bridge.

9. Control system: used for the control of the whole system, there are PLC and PLC + PC control mode, both are automatic control mode, PLC + PC control is more convenient to use, not only can conveniently modify the process parameters, but also can record real-time parameters, convenient for future inquiries. PC-controlled equipment can also set different permissions for different operation levels, not only effectively protect process data, but also effectively prevent mode quality and safety accidents.