舶用機関から排出されるN_2O等有害排ガスの評価及び処理に関する研究

概要

論文の詳細を見る
Form the viewpoint of global environment protection, regulations for prevention of air pollution from ships have been discussed in the International Maritime Organization (IMO) and the regulations about NOx and SOx are expected to enter into force January 1st of 2000. In addition to the above, IMO will revise the regulations every five years. Then emission restriction will be expected to apply to other air pollutants including N_2O and Particulate Matter (PM) in the near future. Under these circumstances, we studied the evaluation of the harmful exhaust emissions from marine diesel engines the effective techniques for reduction of these emissions. The study was conducted as follows: First, the influence of fuel properties on emission characteristics including PM was investigated by experiments with various marine residual fuels that were collected from various regions. Secondly, the change of NOx concentrations with the alteration of engine operation conditions and variation of shaft torque was investigated experimentally by using a 4-stroke diesel engine. And the change of emission characteristics of other harmful components in exhaust gas was examined for the various combinations of engine loads and fuel oil species that were used. Next, the effect of emulsified fuel on NOx reduction in on-board test was verified by settling an apparatus for supplying emulsified fuel to a diesel generator in ship. Furthermore, the influence of operation with emulsified fuel on engine parts was also investigated. Finally, the influence of the fuel injection system with emulsified fuel on emission characteristics from marine diesel engines was investigated by using a 4-stroke diesel engine. And adaptability of Selective Catalytic Reduction (SCR) system for marine diesel engines was investigated by using catalyst (TiO_2-V_2O_5) and aqueous urea solution as reducing agent experimentally. The following results are obtained: 1. Influence of fuel properties on emission characteristics 1) Influence quality of fuel can expressed by Calculated Carbon Aromaticity Index (CCAI). 2) NOx emission rate increases with an increase of CCAI of fuel, and soot emission rate increases with an increase of sulphur content. 2. NOx emission characteristics with the shaft torque change of marine diesel engines NOx concentration during the periodic shaft torque variation can be dealt with that as equivalent to the corresponding NOx concentration at an average load. 3. The emission characteristics of harmful exhaust components with emulsified fuel 1) NOx concentration decreases with an increase in the water ratio. Meanwhile, the reductuin rate of NOx concentration with a decrease in engine load for Marine Diesel Fuel (MDF), while it increases for the blended fuel of MDF and Marine Fuel Oil (MFO). 2) N_2O concentration increases with degradation of fuel oil, whereas it decrease with emulsified fuels. The increase in N_2O concentration with degraded fuel oil is expected to be caused by reduction of NO with SOx. 4. Influence of the fuel injection system on the marine diesel engine with emulsified fuel 1) Although the smaller-hole nozzle had superiority on emission characteristics, in the case with unemulsified fuel, the standard-hole nozzle caused better NOx reduction rate in the case with emulsified fuel than the smaller-hole nozzle. 2) More then 60% of NOx reduction rate, was identified in the engine operating at higher loads with emulsified fuel of 60% water ratio without any increase in other harmful components of exhaust gas. It suggests that the operation with emulsified fuel of higher water ratio is extremely effective on NOx reduction excepting at lower engine loads. 5. Emission characteristics from on-board engine with emulsified fuel 1) Emission characteristics from on-board engine almost agreed with those on shop test, that is, NOx concentration decreased with an increase in water ratio. 2) NOx emission increased with the passage of time. 6. Influence of operation with emulsified fuel on engine parts 1) Parts in fueling system had no considerable corrosion or wearing, except the inside of nozzle hole of fuel injection nozzle. 2) Hard deposit and melting traces were provided on the top piston head, while no significant changes were observed on other parts in combustion and exhaust system. 7. Study and adaptability of SCR system for marine diesel engines 1) This SCR system is useful for engines using Marine Fuel Oil (MFO) as well as Marine Diesel Fuel (MDF). 2) In addition to NOx reduction, N_2O reduction is possible by using this SCR system.
独立行政法人海上技術安全研究所の論文
2000-09-13

舶用機関から排出されるN_2O等有害排ガスの評価及び処理に関する研究

スポンサーリンク

概要

著者

関連論文

スポンサーリンク