Combination membrane system for producing nitrogen enriched air

摘要

A system for providing nitrogen enriched air (NEA) from ambient air uses at least two gas separation membranes that are selectively gas permeable for oxygen and nitrogen. The oxygen/nitrogen selectivity and oxygen permeance of two of the membranes are different such that (1) the selectivity of first membrane is less than the second membrane and the oxygen permeance of first membrane is greater than the second membrane, or (2) the selectivity of first membrane is greater than the second membrane and the oxygen permeance of first membrane is less than the second membrane. The system is very compact, is energy efficient, and highly effective for generating NEA. It is ideally suited for mobile, remote and specialized end use applications, such as automotive vehicles, marine vessels, off-shore platform fuel storage and especially for supplying NEA to blanket ullage of onboard aircraft fuel storage tanks.

主权项

1. A nitrogen enriched air (NEA) production system comprising
a first gas separation module comprising a first selectively gas permeable membrane defining a first feed-retentate chamber on one side of the first membrane and a first permeate chamber on a side of the first membrane opposite the first feed retentate chamber, the first membrane having an oxygen/nitrogen selectivity, α1, greater than 1.0, and an oxygen permeance f1, a second gas separation module comprising a second selectively gas permeable membrane defining a second feed-retentate chamber on one side of the second membrane and a second permeate chamber on a side of the second membrane opposite the second feed retentate chamber, the second membrane having an oxygen/nitrogen selectivity, α2, greater than 1.0, and an oxygen permeance f2, and a transfer line capable of feeding a gas from the first feed-retentate chamber to the second feed-retentate chamber and in which α2 is greater than α1, and f1 is greater than f2.