Patent ID: 8409324

Claim:
A method for making a dry component gas from a relatively wet feed stream, the method comprising: a) passing a feed gas stream through a dehydration membrane module, the module having a feed end and a product end, to produce a dry product gas, b) directing the dry product gas into a PSA unit so as to separate the dry product gas into a purified product gas and a waste stream, and c) conveying said waste stream from the PSA unit into the dehydration membrane, the waste stream being conveyed to a point in a vicinity of the product end such that the waste stream can flow countercurrently to the feed gas stream and can function as a sweep gas for the dehydration module, wherein step (c) includes selecting an injection point along the module, for the sweep gas, according to the following steps: d) determining a water vapor concentration of said sweep gas, e) calculating a water vapor concentration of said feed gas stream flowing within the module, the calculating step being performed for a plurality of locations along the module, and f) injecting the sweep gas at a location along the module such that the water vapor concentration of said feed gas stream at said location is greater than or equal to the water vapor concentration of said sweep stream.