Importance

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Abstract

An air separation method for supplying gaseous oxygen to meet the requirements of a variable demand cycle. In accordance with present invention, air is rectified by a double column low temperature rectification process to produce a nitrogen rich vapor and liquid oxygen in high and low pressure columns. The nitrogen rich vapor and the liquid oxygen are withdrawn from the high and low pressure columns, respectively. The nitrogen rich vapor is partially heated within a main heat exchanger of the process and is then, turboexpanded to create plant refrigeration. When a demand for gaseous oxygen exists, a product stream formed of withdrawn liquid oxygen is pumped to delivery pressure and the nitrogen rich vapor is diverted within the main heat exchanger from being partially heated and expanded and is fully heated, compressed and then condensed against vaporizing the product stream to form the gaseous oxygen. The condensed nitrogen is then flashed into a flash tank. The flash vapor is added to the diverted nitrogen rich vapor to increase the vaporization rate of gaseous oxygen. The resultant liquid is introduced into the low pressure column as reflux to allow the withdrawal of the liquid oxygen. Any excess amounts of the liquid oxygen and condensed nitrogen not immediately used are stored.

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First Claim