舶用機関における大気汚染物質の抑制技術に関する研究

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The regulation of exhaust emissions from ships was discussed as prevention policy of air pollution by the International Maritime Organization (IMO) from the viewpoint of global environmental protection, and it will go into force in the near future. At the same time, the proposal that revises the contents every five years after the regulation starts was adopted, which suggests that other harmful emissions will be regulated in the near future as well as NOx and SOx. On the other hand, some NOx reduction methods which are expected to be utilized for marine diesel engines have been found to increase other harmful emissions. Thus, this study primarily aims combustion improvement and control with electronic control of fuel injection system and valve driving system to reduce air pollutants in exhaust gas totally. In addition, emission state of Volatile Organic Compound (VOC), of which behaviors have been unknown in the case of marine diesel engines, and influence of fuel and other factors on composition of Particulate Matter (PM) are investigated as well as adaptable measurement methods of VOC and PM for ships. The following results were obtained: 1. In the study on electronic control of fuel injection system of marine Diesel engine, a trial fuel injection apparatus was manufactured to aim simultaneous reduction of NOx and PM, and the following results were obtained: a) Electronic control of fuel injection system caused significant reduction of PM emission. b) Optimization of fuel ignition timing by electronic control provided a considerable effect at lower engine loads in particular. At 25% engine load, the optimum ignition timing, which improved NOx emission, PM emission and Specific Fuel Consumption (SFC) simultaneously, was obtained. c) At higher engine loads, an increase in actuating hydraulic pressure could improve SFC and PM emission. d) For emulsified fuel, no obvious optimum fuel ignition timing was obtained because pressure drop in the rear part of injection period increases exhaust gas temperature. 2. In the study on operation of electronic-controlled Diesel engine, electronic control of valve driving system was conducted following fuel injection system to aim further improvement of SFC and simultaneous reduction of NOx and PM by the synergistic effect of these apparatuses, and the following results were obtained: a) Easy determination of desirable fuel ignition timing based on fuel injection timing and ignition delay by displaying of average value of each timing datum was enabled. And, it was found that exhaust valve opening timing is available as an index of engine operation. b) At lower engine loads, the optimum ignition timing, which improves NOx emission and SFC simultaneously, was obtained. c) It was found that delaying of exhaust valve opening timing might improve NOx emission and SFC simultaneously. 3. In the study on measurement and evaluation of VOC from marine Diesel engine, the measurement was conducted for experimental and on-board engines to establish VOC measurement adaptable to actual ships, and the following results were obtained: a) In general, the concentration of methane, ethylene, propylene and benzene in exhaust gas was considerable while ethane and propane were slight. b) In all experiments, methane concentration in exhaust gas fell below its concentration in ambient air. Thus, evaluation of methane emission is to be based on net emission coefficient or IPCC net emission coefficient. 4. In the study on on-board PM measurement, the measurement was conducted for experimental and on-board engines to establish PM measurement adaptable to actual ships, and the following results were obtained: a) Some problems such as participation of PM in measurement system remain for Fast FID Method, Filter Oscillation Method and 6-ray Absorption Method. b) Fast FID Method has enough maneuverability and response for real-time measurement. However, suitable evaluation function should be applied to consider the influence of sulphate in PM. c) Filter Oscillation Method is very available because it has portability and quick response. However, it is affected by ship rolling so that some arrangements should be treated. d) 6-ray Absorption Method endures ship rolling. However, the improvement of control program is demanded to evaluate the errors.
独立行政法人海上技術安全研究所の論文
2002-02-22

舶用機関における大気汚染物質の抑制技術に関する研究

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