Nitrogen removal from natural gas. Quarterly report, September 1, 1996--November 30, 1996

Membrane processes have been considered for natural gas denitrogenation. The challenge, not yet overcome, is to develop membranes with the required methane/nitrogen separation characteristics. Our calculations show that a methane-permeate membrane with a methane/nitrogen selectivity of 4 to 6 would make a membrane denitrogenation process viable. Phase I of this project showed that this target selectivity can be achieved, and that the economics of processes based on this selectivity would be competitive. Gas permeation measurements with membranes prepared from two rubbery polymers and a superglassy polymer showed that two of these materials had the target selectivity of 4 to 6 when operated at temperatures below -20{degrees}C. An economic analysis showed that a process based on these membranes is competitive with other technologies for small streams containing less than 10% nitrogen. Hybrid designs combining membranes with other technologies are suitable for high-flow, high-nitrogen-content streams. The Phase I work demonstrated the potential usefulness of using methane-permeable membranes for the denitrogenation of natural gas. The objective of Phase II is to determine which of the two candidate membranes is the most suitable for scale up to membrane modules for laboratory tests followed by field tests of the process