Project completed – “Effect of LNG gas blends on two-cycle compressor engine performance and emissions”, to answer the question: “For low emissions engines (e.g. <3/BHP-hr NOX), will moderate variations in fuel composition be an important influence in maintaining compliance with air permits?”
Southwest Research Institute has completed an investigation of the effect of LNG fuel gas blends on two-cycle compressor engines. Various percentages of ethane, up to 17%, were used to simulate the range of BTU values of LNG cargoes, and the resulting slugs of fuel gas that compressor engines may encounter. Assuming that some blending with conventional supply is likely to occur upstream of the compressor station fuel header, and that 17% ethane is an aggressive assumption for an LNG cargo, this testing likely encompasses a worst case LNG fuel gas scenario for gas compression engines. Corresponding values for 17% ethane are: LHV: 1024 Btu/scf, Wobbe index: 1400, Methane number: 74. The testing was conducted on a low-emissions GMVH-6 operating at a nominal baseline level of 2 grams NOx/bhp-hr. Testing was conducted in both pre-combustion chamber and open chamber configurations.