Method for varying liquid production in an air separation plant with use of a variable speed turboexpander

摘要

A method of producing a liquid product stream, for example, a liquid nitrogen product stream, at a production rate that is selectively varied. This variation is produced in either a waste expansion or air expansion process by increasing the pressure and flow rate of the feed stream during periods in which a high rate of liquid production is desired without substantially increasing the pressure of the exhaust stream produced by a variable speed turboexpander. This increases the expansion ratio across the turboexpander and therefore the refrigeration supplied to increase liquid production. At the same time, the increase in flow rate prevents a decrease in the performance of the variable speed turboexpander.