Assembly and Method for Reducing Ammonia in Exhausts of Internal Combustion Engines

摘要

A system for reducing ammonia in exhaust gas generated from a lean burn internal combustion engine includes an oxidation catalyst, a selective reduction catalyst (SCR), a cooling unit, and a three-way catalyst. Exhaust gas generated by the engine passes through the oxidation catalyst to oxidize carbon monoxide from the exhaust gas to form carbon dioxide. Nitrous oxide (NOx) compounds in the exhaust gas are reduced in the SCR to form nitrogen and water. The exhaust gas is then cooled in a cooling unit and then passed over the three-way catalyst. The three-way catalyst causes ammonia in the cooled exhaust stream to react to form less harmful compounds, such as nitrogen and water.

主权项

1. A method of operating a catalytic system for reducing emissions of ammonia from a lean burn internal combustion engine, the method comprising:
combusting a hydrocarbon fuel in an internal combustion engine having an air to fuel ratio (AFR) greater than a stoichiometric AFR needed for a complete combustion of said fuel; passing an exhaust gas generated from said engine over an oxidation catalyst, said oxidation catalyst configured to oxidize CO in said exhaust gas to form CO2; passing said oxidized exhaust gas over a selective catalytic reduction (SCR) converter to form an oxidized and reduced exhaust gas, said SCR converter configured to reduce NOx in said oxidized exhaust gas to form N2 and O2; cooling said oxidized and reduced exhaust gas to a temperature of 475-640° F.; and passing said cooled exhaust gas over a three-way catalyst to reduce a concentration of NH3 in said cooled exhaust gas.