Relative Performance of High-Pressure Fuel Gas Delivery on Large-Bore, Two-Stroke Natural Gas Engine
The natural gas transmission industry and chemical process industries use over 8,000 large-bore, natural gas engines for compressing natural gas and process gases. Currently, fuel gas is metered into these engines through mechanically actuated gas admission valves (i.e., fuel injectors) which inject natural gas directly into each power cylinder. This fuel is injected at low pressure (typically 15-40 psi above manifold pressure), which requires that the fuel be delivered during the late scavenging and early compression stages. Recent efforts to reduce emissions from these engines provide ample evidence that these engines are characterized by poor mixing of air and fuel in the cylinder. One promising technique to enhance in-cylinder mixing is through the use of high pressure fuel delivery. A project was sponsored by the Gas Research Institute to determine the effects of high pressure fuel deliver on large bore 2-stroke natural gas engines. In this project, a high pressure fuel delivery system was built to deliver fuel gas to a Cooper-Bessemer GMV engine a large-bore two stroke engine common to the gas transmission industry. High pressure electro-hydraulic fuel valves were utilized to deliver fuel into each cylinder at pressures ranging from 300-700 psi. In this paper, the performance of the engine operating with high pressure fuel valves is compared to the performance of the same engine operating with r and mechanical valves operating at conventional fuel gas pressure. The effect of high-pressure fuel deliver on criteria pollutants (NOx, CO, THC), toxic pollutants (primarily formaldehyde), combustion stability, and fuel consumption are discussed.