NAMS 2002 Workshop - ICOM 2008

EMS Barrer Prize – 2
Thursday July 17, 9:30 AM-9:55 AM, Maui
Membrane Separation of Nitrogen from High-Nitrogen Natural Gas: A Case
Study from Membrane Synthesis to Commercial Deployment
R. Baker (Speaker), Membrane Technology and Research, Inc., USA - rwbaker@mtrinc.com
Fourteen percent of U.S. natural gas contains excess nitrogen, and cannot be
sent to the national pipelines without treatment. Nitrogen is difficult to remove
economically from methane, by any technology. Currently, the only process used
on a large scale is cryogenic liquefaction and fractionation, but this technology
requires economies of scale to be practical. Many owners of small gas fields
cannot produce their gas for lack of suitable nitrogen separation technology.
This paper describes the development of selective membranes to treat natural
gas containing high concentrations of nitrogen. Membranes selectively permeate
either nitrogen or methane, the principal constituent of natural gas. Our work has
shown that methane-selective membranes are generally preferable. We have
produced membranes with high permeances and methane/nitrogen selectivities
of approximately 3-3.5. This selectivity is modest, so commercial systems often
require multi-stage or multi-step process designs. Despite the design complexity
and compression requirements, multi-step/multi-stage membrane systems are
the lowest cost nitrogen removal technology in many applications.
The development of this membrane technology to the commercial scale is
described. To date, nine membrane-based systems for nitrogen removal during
natural gas processing have been installed.