Urea pyrolysis chamber and process for reducing lean-burn engine NOx emissions by selective catalytic reduction
AssigneeClean Diesel Technologies, Inc.
InventorsJeremy D. Peter-Hoblyn, Eric N. Balles, Theodore J. Tarabulski, John E. Hofmann, James M. Valentine
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Abstract
Urea is pyrolyzed in a chamber designed to facilitate gasification of the urea by pyrolysis with conversion of urea to ammonia and isocyanic acid (HNCO) with water vapor and carbon dioxide. The product gases are introduced into exhaust gases from a lean-burn engine, preferably upstream of a turbocharger. The exhaust gases are then contacted with an SCR catalyst.
Claims3
An apparatus for reducing the emissions of Nox from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to a SCR reactor effective for selective catalytic Nox reduction, comprising:
- a pyrolysis chamber for pyrolizing urea fed as an aqueous solution including heated internal surfaces and having openings therein to permit discharge of gases generated by pyrolysis of urea and vaporization of water;
- means for passing the gases generated by pyrolysis into the exhaust passage containing exhaust gases;
- means for passing the exhaust gases containing the gases generated by pyrolysis to a SCR reactor;
- spray means capable of spraying the urea solution into the pyrolysis chamber;
- and said spray means comprising an injector nozzle having associated lines for feeding the solution to the nozzle and returning solution not discharged from the nozzle.
Dependencies are inferred from the claim text.