Variations in Long-Term Emissions Data From NSCR-Equipped Natural Gas-Fueled Engine

This paper describes work by Kansas State University’s National Gas Machinery Laboratory and Innovative Environmental Solutions, Inc. on a project to characterize pollutant emissions performance of non-selective catalytic reduction (NSCR) technology, including a catalyst and air-to-fuel ratio controller (AFRC), applied to four-stroke cycle rich-burn engines. Emissions and engine data were collected semi-continuously with a portable emissions analyzer on three engines in the Four Corners area. In addition, periodic emissions measurements that included ammonia were conducted several times. Data collected from October, 2007, through August, 2008, shows significant variation in emissions levels over hours, days, and longer periods of time, as well as seasonal variation. As a result of these variations, simultaneous control of NO_x to below a few hundred parts per million (ppm) and CO to below 1,000 ppm volumetric concentration was not consistently achieved. Instead, the NSCR/AFRC systems were able to simultaneously control both species to these levels for only a fraction of the time the engines were monitored. Both semi-continuous emissions data and periodically collected emissions data support a NO_x-CO trade-off and a NO_x-ammonia tradeoff in NSCR-equipped engines.