A Novel Approach to Modeling & Demonstrating Significant NOx Emissions Reductions on Large Bore Stationary Engines Fueled by Multiple Gas Types
The natural gas pipeline industry operates the vast majority of large bore (14 bore or greater) stationary engines currently in service. Some of the engines, particularly in the northeast, have been subject to regulations requiring NOx emissions reductions down to 3 g/BHP-HR or less. Over the past five years, the industry has achieved these levels (with varying degrees of effectiveness depending on the design characteristics of the subject engine) through the use of cost-effective emerging fuel injection technologies. While a far smaller portion of the population, other industries also operate large bore engines including Public Owned Treatment Works (POTWs). Depending on location, these engines operate under even more stringent emissions limitations on a variety of fuels. While significantly different in design from typical pipeline engines, the successful reduction of emissions from these engines offers insight into long term options for emissions reduction strategies for pipeline engines. This paper describes the system modifications made to an OEM-PCC fitted low- NOx engine to further reduce emissions to the unprecedented levels required by SCAQMD for 2004. It also describes the parametric continuous monitoring technology required to maintain compliance and optimize engine performance. A detailed evaluation of the design characteristics of the Cooper LSVB-SGC engine and the unique characteristics that facilitate very low NOx emissions without the use of add-on fuel injection technology provides insight into the fundamental mechanisms of NOx formation and reduction. The lessons learned from this case study can be applied to other engine makes and models to aid in the development of combustion modifications for NOx reduction.