High purity sulfur hexafluoride is a gas under normal temperature and pressure, and it is easy to liquefy to liquid under certain pressure after the temperature is reduced. When the ambient temperature rises, the corresponding liquefaction pressure rises accordingly, becoming a gas that is not easy to liquefy. When the temperature exceeds the critical temperature of SF6 by 45.55 ℃, the SF6 will be liquefied by the metatarsal method.

Because the high-purity sulfur hexafluoride is an inert gas and is not miscible with oil, the mixed oil can be easily separated. With international advanced technology, the oil filtering level has reached a level comparable to that of the oil-free system, and the oil can be completely removed.

At present, there are mainly two recovery and storage principles of high-purity sulfur hexafluoride recovery and charging device in the world. One is the principle of freezing liquefaction method: in the process of SF6 gas recovery, under a certain SF6 gas pressure, the refrigeration unit is used to reduce the temperature of SF6 gas to the saturated steam temperature under this pressure, and SF6 gas begins to be liquefied into liquid and stored in liquid form. The advantages are fast recovery and liquefaction.

The other is based on the principle of high-pressure liquefaction, that is, during the recovery of high-purity sulfur hexafluoride, at the ambient temperature at that time, the compressor is used to increase the pressure of SF6 gas to the saturated steam pressure at that temperature, and SF6 gas starts to be converted into liquid and stored as liquid.

The advantage of sulfur hexafluoride recovery and purification unit is that the system is simple, but the disadvantage is that the working pressure of the system is high and the recovery efficiency is low. When the SF6 gas temperature (the SF6 gas temperature after being compressed by the compressor can reach more than 80 ℃) exceeds the critical temperature of 45.55 ℃, it cannot be liquefied. At this time, the SF6 gas with high temperature and high pressure can only be converted into liquid after a period of time when its temperature drops below the critical temperature.

The content of the article comes from high-purity sulfur hexafluoride: http://www.feiliergas.com