Internal combustion (IC) engines are used in a variety of stationary applications ranging from power generation to inert gas production. Both spark ignition and compression ignition engines can be found. Depending on the application, stationary IC engines range in size from relatively small (~50 hp) for agricultural irrigation purposes to thousands of horsepower for power generation. Often when used for power generation, several large engines will be used in parallel to meet the load requirements. A variety of fuels can be used for IC engines including diesel and gasoline among others. The actual fuel used depends on the owners/operators preference but can be application dependent as well. The operation of IC engines results in the emission of hydrocarbons (NMHC or VOC),carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). The actual concentration of these criteria pollutants varies from engine to engine, mode of operation, and is strongly related to the type of fuel used.
ENGINE CONTROL UNIT
PM emissions from stationary diesel engines are more of a concern than those for IC engines using other fuels. Several emission control technologies exist for diesel engine PM control. Oxidation or lean- NOx catalyst can be used to not only reduce the gaseous emissions associated with the use of diesel engines but further provide significant PM control. Likewise, diesel particulate filter systems can be used to achieve up to and greater than 90 percent PM control while in some instances, also providing reductions in the gaseous emissions. Additionally, special ceramic coatings applied to the combustion zone surfaces of the piston crown, valve faces, and head have shown the ability to significantly reduce NOx and PM emissions in diesel engines. These ceramic coatings can be used by themselves or combined with an oxidation catalyst to give even greater reduction of PM. Ceramic engine coatings change the combustion characteristics such that less dry, carbon soot, is produced. Also, when combined with an oxidation catalyst, ceramic coatings allow retarding of the engine to reduce NOx, while CO and particulates are maintained at low levels. In the case of gaseous fuels, ceramic coatings have shown the ability to allow the user to operate their engines with timing significantly advanced generating higher power levels. Also, wider ranges of fuel composition and ambient air temperature fluctuations are tolerated without the deleterious effects of pre combustion. Tests are currently underway to evaluate the effects of the coatings on specific emissions from gaseous fueled engines.
STATIONARY INTERNAL COMBUSTION ENGINES:
Stationary applications for IC engines include:
! gas compression,
! power generation,
! and inert gas production.
PARTICULATE EMISSION CONTROL OF STATIONARY IC ENGINES:
Particulate matter (PM) emission control of stationary IC engines is a concern for diesel engines which emit a relatively high amount of particulate compared to engines using other fuels. Diesel particulate emissions are composed of a variety of compounds from fuel and lube oil combustion, as well as engine wear and sulfate from diesel fuel sulfur. The majority of the particulate consists of carbon and the soluble organic fraction (SOF) consisting of unburned fuel and unburned lube oil. Both oxidation catalysts and diesel particulate filters can be used to substantially reduce diesel PM emissions.
Recently, a catalyst system has been approved with EPA's urban bus retrofit/rebuild program. The program requires that particulate emissions be reduced by at least 25 percent. Other investigations reported in SAE papers...