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On line GC responce time

On line GC responce time

On line GC responce time

We want to replace an old process GC with a new one.  With todays technology we can get a 4 stream analyzer reasonabily.  We want to control the bottoms composition in a demethanizer.  The high priced vendors insists that a multi stream analyzer will take to long (about 20 minutes to cycle back to the stream) where as his unit will update in less than3 minutes.  There is several minutes of surge time in the bottom of the tower.  Is 20 minutes to long?

The present system uses a cascade composition to temperature so there are very slow responces on temperature changes made to the tower bottoms.  The system also will not let temperatures exceed limits on either the high or low end.

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