Vapor Phase Ortho-Para Conversion in the Large CEL-NBS Hydrogen Liquefier

Abstract

The use of hydrous ferric oxide catalyst for converting hydrogen from the ortho to the para state during liquefaction was developed over a year ago here at the National Bureau of Standards and was reported in papers A-3 and A-4 of the 1956 Cryogenic Engineering Conference Proceedings. Since that time, this type of catalyst has been used in the large CEL-NBS hydrogen liquefier. The original 1500 cc of catalyst is still in the liquefier and has performed quite satisfactorily. It has, during the past year, converted a little more than 170,000 liters of liquid hydrogen to around 94 per cent para at an average rate of about 240 liquid liters per hour. During this time we have investigated the feasibility of intermittent operation without reactivating the catalyst and have produced as much as 48,500 liters of liquid during eight separate runs without reactivating the catalyst.