Patent ID: 6185960
Filing Date: 2001-02-13
Classification: F25J,Y10S

Abstract:
A continuous process for the production of pressurized gaseous product by low-temperature separation of air, comprising conducting the process alternately in a gas operation mode and in a combined operation mode, dependent on the demand for particular fluids, said process comprising during both modes of gas operation and combined operation conducting the following common steps:cooling purified feed air under a pressure, partially liquefying the resultant cooled feed air and subjecting the resulting cool feed air to rectification so as to obtain gaseous and liquid fractions,evaporating extremely cold liquid from at least one of the liquid fractions from the rectification under elevated pressure by indirect heat exchange with feed air, heating the evaporated fraction and recovering the heated and evaporated fraction as a pressurized gaseous product,and for the mode of combined operation, conducting the follow steps:generating cold for cooling the feed in an air-refrigeration cycle, comprising pressurizing and work expanding air so as to remove heat from the air, reheating the work expanded air partially countercurrently to the feed air to be cooled, then repressurizing resultant reheated air and re-work expanding said reheated air,thereby forming a recirculating refrigeration cycle, and, withdrawing extremely cold liquid during said rectification and at least partially storine said extremely cold liquid,and for the mode of gas operation, reducing the air in said air-refrigeration cycle to zero, and utilizing the extremely cold stored liquid as a coolant to compensate for cold losses previously covered in the mode of combined operation by the recirculating air-refrigeration cycle.