Hybrid Anti-Fouling Membrane System for Natural Gas Separation

The need for natural gas continues to grow, and recent increases in petroleum prices have been paralleled by large increases in the price of natural gas. However, natural gas at the source often has high concentrations of carbon dioxide and hydrogen sulfide, which must be removed. Although existing commercial polymeric membranes (e.g. cellulose acetate and polysulfone) do a good job of sweetening the natural gas by removing both carbon dioxide and hydrogen sulfide to meet feed line requirements, these membranes are subject to foulant disruptions, which can lead to system outage and loss of productivity. This project will develop natural-gas-sweetening membranes that offer dramatically-improved fouling resistance while maintaining commercial flux and separation targets. The fouling resistance will be broad based and will have application to many membrane foulants and many membrane systems. Phase I demonstrated that the enhanced fouling resistance for natural gas sweetening membranes would significantly reduce the fouling outages. An engineering and economic analysis suggested a 1% increase in natural gas capacity (based on reduced outages) and significant energy savings associated with less loss of natural gas, due to high membrane effective selectivity. Phase II will: (1) optimize system performance related to fouling resistance, separation, flux, and projected cost; (2) fabricate full-scale membrane modules for laboratory and field testing; (3) perform extensive and long term (e.g., 1000 hours) laboratory testing with multiple foulants; (4) perform field testing at an actual site; and (5) upgrade the economic evaluation. Commercial Applications and other Benefits as described by the awardee: The high-selectivity and robust membranes should economically enhance the 30% of natural gas wells in the United States that are in need of upgrading to remove impurities. This represents 62 quads of energy. Additionally, this technology should have application to enhanced carbon monoxide and methane separation in oil recovery operations