The vacuum degree of the coal gas phase drying equipment is maintained at the vacuum degree specified by the process
The basic principle of the coal gas phase drying equipment is to heat and evaporate kerosene in a vacuum state to become high-temperature kerosene vapor. When it encounters a workpiece with a lower temperature in a vacuum tank, it condenses and releases the latent heat of condensation (about 306.6kJ/kg), thereby heating the body of the container. The condensed kerosene is collected and retransmitted to the evaporator through the kerosene conveying system for reheating and evaporation. This cycle repeats multiple times, causing the temperature of the workpiece to continuously rise and the moisture within it to constantly evaporate into water vapor, which is then drawn away by the vacuum system, achieving the goal of thorough drying.
The process stage of coal gas phase drying equipment
Preparation stage
Place the product in a vacuum tank and evacuate it to reduce the pressure to below 700Pa. Meanwhile, the vacuum tank body is heated and insulated. The evaporator preheats the kerosene, gradually raising the temperature of the kerosene vapor outlet of the evaporator from 98℃ to 130℃. The kerosene changes from a liquid state to a vapor state and diffuses in the vacuum tank, fully exchanging heat with the product.
Heating stage
At this point, the vacuum system only requires one maintenance pump to operate, and the vacuum degree of the vacuum tank and the condensation collection tank is maintained at the vacuum degree specified by the process. Kerosene vapor exchanges heat with the transformer, condenses and flows to the buffer tank, then returns to the evaporator, forming a cycle. As the temperature continues to rise, the pressure in the vacuum tank gradually increases due to the evaporation of kerosene vapor and water vapor from insulating materials. At this point, the above-mentioned mixed gas is drawn into 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 temperature of the container body reaches the process requirements, at which point it can enter the depressurization stage.
Depressurization stage (or called low vacuum stage) :
Stop the kerosene from being fed into the evaporator. Continuously extract the mixed gas from the vacuum tank to allow the kerosene remaining in the insulating material to evaporate again for condensation and recovery. Depending on the product capacity and voltage level, the intermediate voltage reduction stage and the heating stage can be alternated several times to achieve the best drying effect.