Development & Testing of a Catalytic Converter for the Reduction of CO and H2CO Emissions from a Two-Stroke Lean Burn Gas Engine
New national and local environmental clean air regulations mandate a reduction in CO and formaldehyde (H2CO) emissions from stationary lean burn internal combustion engines greater than 250 horsepower. Oxidizing catalysts have been proven to be effective at reducing these emissions over reasonably long time periods with four-stroke engines, provided there is adequate oxygen in the exhaust for the oxidation process (>1% 02 works best). However, there are several reasons why oxidizing catalysts have not successfully demonstrated high conversion efficiencies over long time periods with two-stroke engines. The reasons for the problems associated with the application of oxidizing converters to two-stroke, lean burn (2SLB) engines include: products from the combustion of the oil that is force fed to the power cylinders of 2SLB engines carry over into the exhaust and degrade the removal efficiency of the oxidizing catalyst; relatively low exhaust temperatures for these engines reduce the oxidizing efficiency; occasional firing in the exhaust during the starting and stopping os 2SLB engines can damage the catalyst element. The Ajax product line of Cooper Compression has completed an oxidizing converter program with the goal of resolving all of the above issues. The research and development program was completed in January of 2004 with limited field testing underway. The end result of the development program is a catalyst and converter housing which will provide satisfactory long term reduction of CO and H2CO for two-stroke lean burn gas engines. The catalyst and converter have been tested extensively at the design rating for the engine, and the oxidizing efficiencies measured at the conclusion of the test program remained nearly equal to the efficiencies recorded at the start of the tests. This paper documents the methodology used to develop the patent pending technology used in the catalytic converter, as well as a presentation of testing results.