How to Deal With Steam in Vacuum System
In the vacuum drying process of electrical products industry such as transformers, transformers, capacitors, etc., it is required that the vacuum system can remove a large amount of water vapor and solvent in a certain pressure range, and when the drying is terminated, it must reach a lower Ultimate pressure.
For example, a medium-sized transformer, in which the moisture content of the insulating material is as high as 400 to 500 kg, and the entire drying cycle is 70h, requires the vacuum system to remove 90% to 95% of the moisture content within 48h at an inlet pressure of 45 mbar, namely The ability to pump water vapor per hour should be around 15 kg, and it will still return to the original limit pressure of 10-2 mbar after drying.
1. Principle of steam treatment device
① Under vacuum, when the temperature of water or steam is higher than the boiling point, they enter the pump cavity in a gas state.
②The spool valve pump is a heating source itself, and the liquid ring pump provides a low pressure to the separator of the spool valve pump, so the water or other steam discharged to the separator is also in a vacuum state, and the temperature is high enough to keep them In the gas state, any tiny droplets will be evaporated in the separator.
③ The water or other steam discharged to the liquid ring pump is condensed and becomes part of the sealing liquid due to the relatively low temperature in the liquid ring pump.
In order to prevent steam from being condensed in the pump, the oil temperature of this pump must be high enough, generally set in the range of 60 ~ 75 ℃, and the oil temperature higher than 80 ℃ will oxidize the vacuum pump oil, this required oil The temperature can be controlled by automatically adjusting the amount of cooling water entering the slide valve pump.
Adjust the pressure in the spool valve pump separator
If the spool valve pump works at 65 ° C when processing water vapor, the vacuum relief valve installed on the exhaust pipe of the spool valve pump should be set at 15 000-20 000 Pa, which is lower than the water at 65 ° C. Saturated vapor pressure.
Oil pump pressure
The oil pump must be able to operate normally under vacuum, the oil pressure must be maintained at 0.2 ~ 0.4 MPa, continuous oil supply.
Exhaust water vapor experiment
Second, the advantages of steam treatment device
1, can handle a large amount of condensable gas or volatile gas.
2. The extracted steam will not be condensed in the pump, reducing the corrosion of the metal surface.
3. Oil pollution is avoided, the number of oil changes is greatly reduced, and operating costs are significantly reduced.
4. The performance degradation caused by oil pollution is eliminated.
5. Maintain low working pressure in wet process.
