バイオ燃料利用に関するNOxとメタンスリップの同時低減技術の研究

抄録

  Measures to address environmental issues, such as global warming and SOx and NOx emissions, are increasingly gaining importance. With regard to global warming, IMO has set high goals for reduction of greenhouse gases. Biofuels are expected to play an important role in achieving this goal, and in addition to liquid biofuels, the use of gaseous biofuels, such as biomethane made from biogas or wood gas, will also become more crucial in the future. Moreover, active research related to methanation, a method to produce methane by synthesizing CO₂ and H₂, is being carried out. However, the use of gaseous fuels can lead to a problem in gas engines - methane slip. To address this issue, the authors proposed a system that makes it possible to mix gas fuel (such as CH₄) with liquid fuel (such as heavy fuel oil and biofuel) in one cylinder of the engine and introduce exhaust gas out of the cylinder into all other cylinders as EGR (exhaust gas recirculation) gas. When different fuels are used at the same time in the engine, they are usually mixed at first and then carried into all of the cylinders. In contrast, we conducted an experiment using the proposed system by adopting different fuel compositions to each cylinder to take advantage of various combustion characteristics and connecting them with EGR. In this way, we have achieved NOx and methane slip reduction.