ABSTRACT
This chapter discusses that cryogenic liquefaction of the permanent gases, generally considered to be those with normal boiling points below about 200K. The most rapid growth of low temperature cycles has occurred in conjunction with the liquefaction of natural gas. The ideal performance of refrigeration, liquefaction and separation processes can be readily obtained from thermodynamic considerations. The chapter also discusses that industry began in 1895 with the development by Carl Linde of a practical process for liquefying air through the use of the Joule-Thomson expansion effect. In spite of the complexity and high cost of the plant, which has been a drawback to its use, classical cascade liquefiers are used for the liquefaction of natural gas, and an example of an industrial unit. The chapter provides a brief discussion of the principles of gas-separation. The separation and purification of gases is the greatest application of low-temperature, high-pressure technology.
