Process and apparatus for controlling argon column feedstreams
AssigneeThe BOC Group, Inc.
InventorIsmael Al-Chalabi
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Abstract
The present invention relates to methods and apparatus for controlling a process for the separation of air to obtain oxygen, argon, and nitrogen products, and more particularly for controlling the composition of the feedstream to a column for producing crude argon. The nitrogen content of the feedstream is directly analyzed in real time and maintained within a preselected range. The results of the analysis is used to control the operation of the process, for example, by adjusting the reflux or product withdrawal rates. Argon production is thereby maximized without risking a dumping phenomenon in the crude argon column.
Claims32
A process for separation of air by low temperature rectification capable of producing an oxygen, argon and nitrogen product which comprises:
- subjecting air to a two-stage rectification wherein a nitrogen rich reflux liquid from a first rectification stage is introduced into a secomd rectification stage to wash the rising vapor at the top poriton of said second rectification stage and withdrawing from a zone of the second rectification stage where the argon content is high, a feedstream which is passed to a crude argon rectification stage, the improvement comprising analyzing in real time the nitrogen content of said feedstream and controlling the operation of said process in response to the results of said analysis.
A system for controlling the separation of air by low temperature rectification to obtain argon and at least one of oxygen and nitrogen wherein air is subjected to a two-stage rectification in which a nitrogen rich reflux fluid is passed from a first rectification column to a second rectification column for washing the rising vapor of the said second rectification column and wherien a sidestream is withdrawn from said second rectification column and introduced for further rectification into a third column for the production of crude argon comprising:
- (i) a first analyzer means for on-line sensing in real time of the nitrogen content of said sidestream passing from said second rectification column to said third column;
- and
- (ii) a second analyzer means for sensing the oxygen content of a waste nitrogen stream of said second rectification column;
- and
- (iii) a means for controlling the operating line of the second rectification column, based on the inputs of said first and second analyzer means, by controlling the reflux flow of nitrogen rich fluid from said first rectification column to said second rectification column.
Dependencies are inferred from the claim text.