Kerosene gas phase drying equipment insulation drying of oil immersed power transformer is a very important process in the manufacturing process of transformer, which has a great impact on the quality of transformer. If the drying is not complete, the residual water in the insulating material will form an electrode under high electric field and continue to produce free discharge, which will gradually destroy the insulation characteristics of the insulating material. At the same time, in the normal operation of the transformer, the aging process of the insulating material itself will be accelerated, and the service life of the transformer will be shortened. If the drying is excessive, the crystalline water in the insulating material will escape, which will lead to the early aging of the insulating material and the reduction of mechanical strength.

Put the product in the vacuum tank to vacuum and reduce the pressure to less than 700pa. At the same time, the vacuum tank body is heated and insulated, and the evaporator pre heats the kerosene, so that the kerosene steam outlet temperature of the evaporator gradually rises from 98 ℃ to 130 ℃. The kerosene changes from liquid state to steam state, diffuses in the vacuum tank, and fully exchanges heat with the product.

At this time, the vacuum system only needs one maintenance pump to work, and the vacuum degree of the vacuum tank and condensate collection tank is maintained at the vacuum degree specified in the process. The kerosene steam exchanges heat with the transformer, flows to the buffer tank after condensation, and then returns to the evaporator to form a cycle. As the temperature continues to rise, kerosene vapor and water vapor evaporated from insulating materials gradually increase the pressure in the vacuum tank. At this time, the above mixed gas is pumped to the condensation recovery system by the maintenance pump for condensation and separation. The condensed and separated kerosene liquid is then input into the evaporator. The above process continues until the body temperature meets the process requirements, and then it can enter the depressurization stage.

Depressurization stage (or low vacuum stage): stop the transmission of kerosene to the evaporator, continuously extract the mixed gas in the vacuum tank from the vacuum tank, and re evaporate the kerosene remaining in the insulating material for condensation and recovery. According to the product capacity and voltage level, the intermediate step-down stage and heating stage can be carried out alternately for several times to achieve the best drying effect.