Air boiling cryogenic rectification system with lower power requirements
AssigneePraxair Technology, Inc.
InventorsGerald A. Paolino, Raymond F. Drnevich, Neil M. Prosser
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Abstract
An air boiling cryogenic rectification system wherein additional feed air streams are used for vaporizing pressurized liquid oxygen in a once through main heat exchanger and, by turboexpansion, for the generation of refrigeration prior to being passed into the higher pressure column.
Claims9
In a cryogenic air separation process employing a higher pressure column and a lower pressure column wherein feed air is employed to boil the bottom liquid of the lower pressure column and is thereafter passed into the higher pressure column and wherein liquid oxygen is produced in the lower pressure column, the improvement comprising:
- (A) turboexpanding a second portion of feed air to generate refrigeration and passing turboexpanded second feed air into the higher pressure column;
- (B) withdrawing liquid oxygen from the lower pressure column and increasing the pressure of the withdrawn liquid oxygen;
- (C) vaporizing the pressurized liquid oxygen by indirect heat exchange with a third feed air portion which is at a pressure higher than that of the feed air employed to boil the bottom liquid of the lower pressure column, and also with feed air which is subsequently employed to boil the bottom liquid of the lower pressure column, resulting in the production of oxygen gas;
- (D) recovering resulting oxygen gas as elevated pressure oxygen gas product.
In a cryogenic rectification apparatus having a first column, a second column with a bottom reboiler and means for passing a feed stream to the bottom reboiler and from the bottom reboiler into the first column, the improvement comprising:
- (A) a turboexpander, means for passing a second feed stream to the turboexpander and from the turboexpander into the first column;
- (B) means for withdrawing liquid from the second column and means for increasing the pressure of the liquid withdrawn from the second column to produce elevated pressure liquid;
- (C) a main heat exchanger, means for passing a third feed stream to the main heat exchanger, and means for passing said elevated pressure liquid to the main heat exchanger;
- (D) means for passing feed through the main heat exchanger prior to passing it to the bottom reboiler;
- and
- (E) means for recovering gas product from the main heat exchanger.
Dependencies are inferred from the claim text.