A PLANT AND METHOD FOR RECOVERING SULPHUR HEXAFLUORIDE FOR REUSE

摘要

Recovery of re-useable grade sulphur hexafluoride from a contaminated source comprises first evacuating a stream of contaminated sulphur hexafluoride from a transport or storage vessel (10) into a separation via an intermediary and optional clean-up stage, involving scrubbing and filtering. Sulphur hexafluoride in the partially clean-up stream is directly solidified within the separation vessel (30), preferably onto a large surface area tube heat exchanger (4) arranged within the separation vessel (30). Uncondensed contaminant gases are vented to atmosphere, and the solidified sulphur hexafluoride within the separator vessel is melted and transferred to a collection vessel (5) for subsequent reuse. The recovery process re-introduces sulphur hexafluoride obtained from the collection vessel (50) back into the separation vessel (30) for effecting heat transfer to the solidified sulphur hexafluoride thereby to assist in said melting. A valve assembly (53) is provided between the collection vessel (50) and separator vessel (30), which is controlled to allow warm, substantially uncontaminated and previously cleaned sulphur hexafluoride gas to be transferred from the collection vessel (50) to the separator vessel (30) to melt the solidified sulphur hexafluoride. The valve assembly (53) allows the melted sulphur hexafluoride to be transferred to the collection vessel (50) in liquid or gas phase.