EXHAUST EMISSION CONTROL SYSTEM AND EXHAUST EMISSION CONTROL METHOD FOR DIESEL ENGINE USING DIMETHYL ETHER AS FUEL

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control system and exhaust emission control method for diesel engine using dimethyl ether as fuel, capable of supplying fuel heated higher than when leaving a fuel tank to a catalyst device installed in an exhaust passage as reducing agent for reducing NOx in exhaust emissions without need for installing an additional heat exchanger.SOLUTION: The exhaust emission control system includes a catalyst device 31 installed in an exhaust passage 14 of a diesel engine 10, and a reducing agent supply device 32 on the upstream side of the catalyst device 31. A fuel buffer tank 28 installed on the way of a fuel return pipe 27 for returning fuel leaking from a fuel high pressure pump, a common rail and a fuel injection valve to a fuel tank 21 and the reducing agent supply device 32 are connected through a return fuel supply pipe 34 to supply a part of fuel Fi which passes through the fuel return pipe 27 for returning and is heated by the heat from the diesel engine 10 to a reducing agent supply device 32 as reducing agent.