Considerations for small to medium liquefaction plants

Abstract

The basic requirements for a user to size and design small to medium helium liquefaction systems are quite multilayer. The feed gas composition, for example, defines whether impurities can be removed by an internal adsorber system or if a purifier (internal or external) is required and if the purification operation is a continuous or batch process. The liquefaction rate of the system furthermore is dependant on the running time, e.g. if the system is operated during the whole week or stopped on weekends and if a turn-down of the system is required. This will also determine the size of the liquid dewar and storage tank. Another important issue is the availability of liquid nitrogen for pre-cooling purposes. In the US liquid nitrogen is a commodity with a liter price equal to the price for a kW hour of electricity, whereas in Europe LN 2 is more expensive and used only if necessary or easily available. In case LN 2 is used the components like the compressor and coldbox can be smaller with less consumption of electric power. The presentation will cover a number of issues showing important considerations in specifying a helium liquefaction system. © 2012 American Institute of Physics.