【作者】

Vilmar AEsoy，Sergey Ushakov，Erik Hennie

【摘要】

论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。Marine diesel engines are typically operated on high-sulfur residual fuels and can be considered one of the most significant contributors to air pollution. But the current situation is changing in positive direction due to implemented more strict NOx regulations and by setting more strict fuel sulfur limits which certainly has an effect on emitted levels of SOx and particulates. Although, it should be stated that future dramatic reduction of sulfur content may result in limited availability of low-sulfur marine fuels, so their potential alternatives(substitutes) should be defined and thoroughly investigated in advance. In this study different alternative marine fuels including both biodiesel (fish oil, FO) and synthetic diesel(GTL) have been tested in a medium speed marine diesel engine and fuel ignition analyzer (FIA) to compare their ignition, combustion and emission characteristics in contrast to reference low sulfur marine gas oil(MGO) and heavy fuel oil (HFO). Experiments were performed at various operating conditions under standard 4-mode propeller curve marine cycle with engine performance, exhaust emissions together with particulate matter(PM) size distributions and corresponding total particle number and mass concentrations being measured and compared at each load point. GTL fuel was found to have the highest cetane number, hence the shortest ignition delay among the tested fuels and simultaneously provided 1-2% higher shaft efficiency comparing to reference HFO. In general, MGO, GTL and FO showed a rather similar combustion performance in terms of both cylinder pressure and rate of heat release, which was distinctively different from that of high-sulfur heavy fuel oil. Both MGO and GTL showed a very similar behavior in terms of gaseous emissions (comparing to that of HFO) with NOx and CO2 concentrations being decreased, HC levels being increased and CO emissions showing some variation depending on actual load conditions. FO, in its turn, allows reducing both emitted CO2, CO and HC concentrations, but NO, levels were slightly increased. All the aforementioned effects are likely associated with the alternative fuels chemical composition and physical properties, e.g. lower levels of sulfur, ash and aromatics, higher cetane number and oxygen content(for FO) in fuel. All these factors are believed to be also important in explaining pronounced PM reduction, both in terms of PM mass and total number concentrations, that was observed from MGO, GTL and FO. The highest positive effect was found from FO with more than 75% of PM mass reduction (mainly related to reduction in number of big carbonaceous particles) and is likely associated with its high content of fuel-embedded oxygen. The registered particle size distributions were fairly bimodal for MGO, GTL and FO with pronounced carbonaceous accumulation mode and nucleation mode composed of ash compounds and originating from high lube oil emissions with the nucleation for semivolatile compounds is believed to occur via heterogeneous nucleation process. Particle size distributions were unimodal (actually contained two overlapping modes) from HFO fuel and showed somewhat lower concentrations of big carbonaceous particles, which can be explained by high content of metallic ash compounds (in heavy fuel oil) acting as a catalyst and hence enhancing the process of soot oxidation. This study was performed by MARINTEK in co-operation with DNV, Fueltech Solutions and Norwegian University of Science and Technology (NTNU) as a part of KMB project # 10348601, which was funded by the Research Council of Norway.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

返回