EXHAUST PURIFICATION DEVICE FOR GAS ENGINE

摘要

Provided is an exhaust purification device for a gas engine using a gaseous fuel containing unburnt methane as a main component. In particular, an exhaust purification device suitable for a homogeneous-charge compression ignition type gas engine in which a mixture of pre-mixed gaseous fuel and air is compressed, automatically ignites, and is burnt in a combustion chamber is provided. In an exhaust pathway of the gas engine, an oxidation catalyst (30) and a hydrocarbon oxidation catalyst (31) which has a higher removal rate of methane, etc., than the oxidation catalyst (30) are arranged sequentially from the exhaust upstream side. For example, in a multi-cylinder engine, the oxidation catalyst (30) is arranged in each exhaust branch pipe (20) of an exhaust manifold (4) that has the exhaust branch pipes (20), each connected to a combustion chamber of each cylinder. The hydrocarbon oxidation catalyst (31) is arranged in an inner exhaust passage (27) of a catalyst case (25) having a dual-pipe structure connected to an exhaust downstream side portion of a main exhaust pipe (21) of the exhaust manifold (4).