Prevention of Air Pollution from Ships: Diesel Engine Particulate EmissionReduction via Lube-Oil-Consumption Control

摘要

Strategies to alleviate particulate emissions from diesel engines on boardvessels operating in coastal waters are being investigated. The approach is to determine the effectiveness of reducing engine lube-oil consumption as a means to reduce particulate pollutants. In this study, simultaneous lube-oil consumption and particulate emission data were collected on a single cylinder diesel engine for various speeds and loads using three piston-ring and intake-air pressure configurations. A sulfur dioxide-based measurement system was used to measure lube-oil consumption by tracking the sulfur from the lube-oil in the exhaust while using ultra-low sulfur diesel fuel. A scaled down version of a Constant Volume Sampling (CVS) system with a dilution tunnel was used to measure total particulate emission rate. Lube-oil contribution to particulate was determined using chromatography. The aggregate data show that an average of approximately 64% of the consumed lube-oil ends up as a significant portion of the total particulate. This percentage is lowest at the medium-load conditions at which moderately high exhaust temperatures and lean air-fuel ratios provide an environment suitable for the partial or complete oxidation of the consumed lube-oil. Significant reductions in particulate emission rate could be obtained by controlling engine lube-oil consumption. This can be effected by changes in piston-ring designs (tension and shape, for example) or by manipulating engine operating conditions, such as intake air-pressure, and possibly via other lubrication-system related variables. Replacement of piston rings with low-lube-oil-consumption designs, for example, could be an option with existing engines.