Double stage cryogenic trap - with screen under vessel cooled by vapour from vessel escaping through coil

摘要

A double state cryogenic trap located in a duct through which a gas is pumped, has a vessel (22) into which cryogenic liquid such as liquid nitrogen is fed through a connection (24) at the top, with a small bore outlet tube (30) also positioned near the top which passes down between the side of the vessel and the inside of the duct (10), then forms a coil (28) around a horizontal screen (26) under the base of the vessel (22), with a return portion travelling upwards parallel to the beginning of the tube, to discharge to atmosphere through a hole (32) in the duct, above the level of the vessel. The vapour given off by the fluid inside the vessel escapes through the tube and coil thus cooling the screen.