| abstract |
For generating gaseous ammonia formed by hydrolysis of an aqueous solution of urea at elevated temperature and pressure that is sent into the engine exhaust gas as it flows through the exhaust system of the IC engine An apparatus (1) is disclosed. The device (1) is arranged in the exhaust system and has an inlet (2) for exhaust gas and an outlet (3) for exhaust gas so that the exhaust gas flows through the device (1) in use. . An aqueous solution of urea is housed in a reaction vessel, which in use, is used at the inlet so that when the exhaust gas flows from the inlet to the outlet, the vessel and hence the urea solution is heated by heat exchange with the exhaust gas. Located between and the exit. A pump (32) is provided for pumping the urea solution into the reaction vessel, and the controller (33) controls the pump (32) in response to changes in the NOx output from the IC engine, thus increasing the NOx output. In response, the controller (33) controls the pump (32) to increase the level of urea solution in the reaction vessel, thereby increasing the production rate of gaseous ammonia in the reaction vessel. Increase the surface area of the urea solution available for heat exchange with the exhaust gas. [Selection] FIG. |