Effects of Emulsified Fuel, Fuel Injection Control and EGR that Uses Exhaust Gas from Gas Engine on Emission Characteristics of Marine Diesel Engine

Abstract

  Lean-burn gas engines contribute to CO₂ reduction, and exhaust gas from these engines emit low levels of NOx, SOx and smoke, but it has the problem of methane slip. In contrast, exhaust gas from diesel engines has a small amount of methane, but contains a large volume of NOx. The use of EGR that utilizes exhaust gas from gas engines for marine diesel engines may serve to reduce NOx and methane emissions simultaneously.

  The authors investigated possible effects of EGR that uses exhaust gas from the gas engine together with emulsion fuel and fuel injection control on emission characteristics of the marine diesel engine. The results showed that while NOx emission was greatly reduced with EGR, the amount of produced smoke increased. When the engine load was 75 percent, the use of emulsion fuel worked to reduce the volume of smoke, but when the load was slashed to 25%, more smoke was produced. We found that pre-injection was effective to address these problems at the same time. We also confirmed that the system cut down methane emission by 75% to 90%.