Low-Cost NO_x Reduction Retrofit for Pump Scavenged Compressor Engines

The Clean Air Act Amendments of 1990 and the resulting individual State Implementation Plans will require many natural gas pipeline operators to install NO_x reduction equipment on existing compressor station engines. A program was undertaken to develop lower cost NO_x control options for these engines as compared to traditional techniques. The initial work, described in this paper, focused on the development of a low-cost retrofit package for Cooper-Bessemer GMV and GMV-TF pump scavenged integral compressor engines. The retrofit concept relied on highly dilute combustion to achieve low engine-out NO_x emission rates. A significant portion of the effort concentrated on low-cost methods for delivering the required air charge and ignition enhancements to achieve reliable and robust combustion. The prototype retrofit kit has been installed on a GMV-6 in gas compressor service. Performance results showed a 70 percent reduction in NO_x emission rates without a corresponding increase in HC emission rates.