A Laboratory Plant for Gas Liquefaction

A prototype gas liquefaction plant has been designed and manufactured for Politecnico di Torino cryogenic laboratory and has been used for cryogenic applications like superconducting cables and low temperature refrigeration devices. The plant is able to liquefy nitrogen and, by means of little changes, hydrogen and other cryogenic °uids too. The thermal energy is removed by four high speed (up to 360 000 revolutions per minute) helium turbines that are connected in series. The gas liquefaction is carried out by the cooling condensation process of the gas °ow that feeds a 0.15m3 super insulated tank that is cooled inside. The cryogenic system is based on the Claude and Collins cycles, fed with helium that provides the cold sink. The paper shows the characteristics of the plant main components, and the time history of the measured temperatures, pressures, and °ow rates during the plant start-up, as well as the steady state lique¯ed gas production rate. From the energetic point of view, the plant performance is acceptable for a research laboratory and the plant e±ciency is not far from that of commercial larger size plants.