One of the biggest challenges for engines used in Marine industry is to burn fuels of varied compositions, since the vessels often move from regions with highly regulated fuels to regions with no regulations, unlike their on-road and other stationary counterparts. This poses an enormous risk to the performance, reliability, durability and service life of engines that employ exhaust gas recirculation (EGR) as a prime technology to meet stringent emission regulations, laid out by various regulating bodies across the globe like the United States (U.S.) Environmental Protection Agency (EPA) and International Maritime Organization (IMO).
Operating on fuels with higher Sulfur content poses a risk of reduced engine component life, due to the formation of concentrated Sulfuric acid (H2SO4), which, if not handled carefully, would lead to higher rates of corrosion on engine parts. Hence, the ability to predict the potential for H2SO4 formation as well its quantity to be handled is essential.
This research paper focuses on the development of an empirical model to predict the amount of H2SO4 condensate that can be formed in the air handling system of medium speed diesel engines. The model utilizes a combination of fundamental physics, chemistry, thermodynamics and chemical kinetics. The H2SO4 prediction calculation employs basic measurable parameters from a running engine, such as engine speed, load, EGR flow rate, fuel flow rate, fuel Sulfur concentration to compute a molar balance of hydrocarbon fuel and combustion air quantities along the entire range of engine operation, providing the amount of H2SO4 condensate formed. This is done primarily at EGR cooler, where the recycled exhaust gas gets cooled primarily and the EGR mixer, where it gets cooled further after coming in contact with the charge air and are identified as critical locations.