Distributed power generation is an efficient method for reducing CO2 emissions through the elimination of transmission losses. Co-generation has similar benefits with higher thermal efficiency. Natural gas engines are very popular for these applications. Unfortunately, these engines emit significant levels of methane, which is a greenhouse gas. Reduction of methane emissions would greatly improve the environment and provide greenhouse gas emissions credits. The exhaust temperature downstream of the turbocharger in a natural gas engine is typically below
Misfiring events are common in natural gas engines. During misfiring events, the catalyst will see a sudden increase in hydrocarbon (methane). When this pulse of hydrocarbon hits the catalyst, it will be oxidized and generate a large exotherm which could lead to catalyst failure (mechanical and/or chemical). This issue is critical for a pre-turbo catalyst:
1) Mechanical failure of the catalyst could lead to catastrophic turbocharger failure, a result of the turbine blades being damaged.
2) Misfiring with catalyst installed before the turbocharger is more likely to ignite the methane pulse because of the higher temperatures in this location. High exotherms from ignition could negatively affect catalyst performance.
Through careful catalyst design, one can minimize this risk and this paper will address these issues.
Lean-burn natural gas engines are very popular for applications involving power generation and co-generation. On-site power generation reduces power transmission losses and in the case of co-generation also supplies heat. Unfortunately, due to incomplete combustion within these engines the exhaust contains trace amount of hydrocarbons with up to 1000 ppm of methane. Since methane has a greenhouse warming potential of about 20 to 50 times that of carbon dioxide, its emissions are becoming an area of concern. Although