AFTER-TREATMENT APPARATUS OF ENGINE-EXHAUST GAS USED IN CNG VEHICLE

摘要

According to an embodiment of the present invention, an after-treatment apparatus for an exhaust gas for a compressed natural gas (CNG) vehicle comprises: an oxidation catalyst part; a selective reduction catalyst part; and a urea mixing pipe. The oxidation catalyst part is longitudinally installed to allow introduction of an exhaust gas discharged from an engine. The selective reduction catalyst part is formed in parallel with the oxidation catalyst part to allow introduction of the exhaust gas passing through the oxidation catalyst part. The urea mixing pipe is formed to connect the oxidation catalyst part with the selective reduction catalyst part. An exit of the oxidation catalyst part connected to the urea mixing pipe is formed with an internal diameter gradually becoming smaller. Accordingly, the back pressure of the exhaust gas discharged from the oxidation catalyst part can be reduced, and flowage uniformity within the oxidation catalyst part can be improved such that the amount of exhaust gas passing through a catalyst can be increased, thereby increasing efficiency in purifying the exhaust gas.