舶用2サイクル機関におけるNOxの排出特性とその低減方法に関する一考察

抄録

At present, there is no regulation on NOx emission from marine diesel engine. IMO MEPC 30 th session, however, has presented a target figure for the emission in 1990. Especially in the harbor and the straits, it is considered that NOx emission from ship damages the environment because of the concentration of the vessels in a limited area. In order to clarify the characteristics of NOx emission from CPP (controllable pitch propeller) ship and FPP (fixed pitch propeller) ship in the harbor, and to discuss the method of reducing the emission, ship speed [knot], NOx emission [ppm], engine output [kW], indicator diagram were examined by using a 1990GT/2795 kW ship equipped with CPP. In addition, cylinder gas temperature and heat release rate were calculated from indicator diagram to analyze the relationship between NOx emission and combustion. The results obtained from the examinations are as follows: (1) at the same engine load, driving CPP at higt revolution is effective in reducing the NOx emission; (2) maximum cylinder gas temperature correlates well with NOx emission [kg/h] ; (3) new criterion is proposed to estimate the reduction of NOx emission from sailing ship.