Producing ammonium carbamate and reducing nitrogen oxides [patent application]

A process for reducing nitrogen oxides in an exhaust stream in large-scale applications, such as marine vessels and powerplants, and for use at a filling station or a depot.The process comprises providing a first reservoir (12) having a first composition therein, the first composition comprising aqueous urea; transferring a portion of the first composition to a second reservoir (14): heating the portion of the first composition in the second reservoir to generate a second composition, the second composition comprising aqueous ammonium carbamate: and introducing a portion of the second composition into an exhaust scream (10) comprising nitrogen oxides. The second reservoir comprises at least two tanks (14A, 14B, 14C), an anti-slosh device; and the second composition is heated to avoid precipitation of ammonium carbamate. A portion of the second composition is introduced into the exhaust stream by means of pressure-driven injection and a control system may be employed that responds to onboard diagnostics