Formaldehyde Formation in Large Bore Engines Part 2: Factors Affecting Measured CH2O

Abstract

Current research shows that the only hazardous air pollutant of significance emitted from large bore natural gas engines is formaldehyde CH2O. A literature review on formaldehyde formation is presented focusing on the interpretation of published test data and its applicability to large bore natural gas engines. The relationship of formaldehyde emissions to that of other pollutants is described. Formaldehyde is seen to have a strong correlation to total hydrocarbon (THC) level in the exhaust. It is observed that the ratio of formaldehyde to THC concentration is roughly 1.0–2.5 percent for a very wide range of large bore engines and operating conditions. The impact of engine operating parameters, load, rpm, spark timing, and equivalence ratio, on formaldehyde emissions is also evaluated. [S0742-4795(00)01004-8]

Summertime Ambient Formaldehyde in Five U.S. Metropolitan Areas: Nashville, Atlanta, Houston, Philadelphia, and Tampa

“…Concomitantly, H2O2 showed a small peak as the HCHO plateau concentration was reached, indicating a relatively aged polluted air mass where photochemical processing has largely been completed. At (10), the aircraft headed S to proceed to a point W of Inglis (11); with the exception of a minor peak (accompanied by a depression in H2O2), HCHO mixing ratio remained stable at ∼7.8 ppb. As the aircraft turned SSW toward (12), it traversed a plume that would appear to be from a nearby point source (because of the high concentrations and sharp spatiotemporal defini-tion), reaching a CN count of 20 000 per cm 3 , and SO2, NO2, and NO (not plotted) peak mixing ratios of 140, 32, and 11 ppb, respectively.…”

“…Ironically, "clean fuels" such as natural gas produce particularly significant levels (9)(10). In large-bore gas turbine engine exhaust, the ratio of HCHO to total hydrocarbons in the exhaust is ∼1-2.5% (11). Exhaust from internal combustion engines powered by sludge digester gas contains 50-200 ppm HCHO (12).…”

Large Eddy Simulation of Combustion Recession: Effects of Ambient Temperature and Injection Pressure

“…This indicates that low-temperature reactions are taking place upstream of the lift-off position after 0.29 ms AEOI. As CH 2 O can be considered as a marker for UHC species since it is formed prior to diffusion flame [37,38], the UHC emissions level is higher in the 800 K than that in the 850 K case due to the absence of combustion recession. The reason for the absence of combustion recession in the 800 K case is likely linked to the local mixture fraction (or equivalence ratio) and local flame temperature.…”

Large eddy simulation of transient combustion and soot recession in the ECN Spray A and D flames

“…OH is the product of high-temperature combustion as aforementioned, while formaldehyde (CH 2 O) is considered here to represent UHC (similarly done in other studies [39,40]). Fig.…”