Reduction Methods of NOx Emission from Ships

Abstract

This paper presented the reduction methods of NOx emission from not marine diesel engines, but marine transportation. In the first part of the paper, evaluations of NOx emission from sailing ships based on naval architecture and marine engineering were examined theoretically. Then, in order to demonstrate the evaluations, fuel injection timing retard and sailing performance under two different conditions (before and after drydock) were examined by using a 603GT/1618kW ship equipped with controllable pitch propeller. The results obtained from the examinations are as follows : (1) the quantity of NOx emission per dead weight and sailing distance that evaluates the emission from sailing ships including engine performance and hull performance is more proper for the NOx estimation than the quantity of the emission per unit time and engine output that evaluates the emission only from engines ; (2) NOx emission from sailing ships can be decreased by reducing NOx emission from engines, coefficient of total resistance and ship speed, and also by increasing propeller efficency ; (3) NOx emitted from ships can be decreased in a global scale by giving attention to the synthetic transport efficiency.