Mapping Study to Characterize NSCR Performance on a Natural Gas-Fueled Engine

Kansas State University’s National Gas Machinery Laboratory and Innovative Environmental Solutions, Inc. are conducting a project to characterize pollutant emissions performance of field gas-fired four-stroke cycle rich burn (4SCRB) engines equipped with non-selective catalytic reduction (NSCR) technology. Engine emissions and operating parameters are being monitored on three engines over an extended period. In addition, a mapping study was conducted on one engine. The NSCR was operated at various controlled air-to-fuel ratios (AF) while emission measurements were conducted and engine operating parameters monitored. NO_x, CO, and oxygen were measured using both EPA reference method technology and the portable analyzer used in the long-term study. In the mapping study, ammonia, formaldehyde, and speciated hydrocarbon emissions were recorded in real-time using an extractive FTIR system. This paper focuses on the engine mapping phase. The mapping tests demonstrated a trade-off between NO_x emissions and CO, ammonia, and hydrocarbon emissions. Richer engine operation (lower AF) decreases NO_x emissions at the expense of higher CO, ammonia, and hydrocarbons. Leaner operation has the opposite effect. The results to date of the semi-continuous monitoring are presented in a separate paper.