Reducing no emissions from an engine by on-demand generation of ammonia for selective catalytic reduction
AssigneeClean Diesel Technologies, Inc.
InventorsJeremy D. Peter-Hoblyn, Eric N. Balles, John E. Hofmann
Life of this patent
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Abstract
A safe, reliable SCR system for reducing NOx emissions from an internal combustion engine hydrolyzes urea or like reagent under sufficient pressure to assure generation of ammonia, without production of solids that could foul injectors or catalysts. The heat for hydrolysis can be provided by the exhaust or an auxiliary means.
Claims13
A method for reducing the emissions of NOx from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NOx reduction, comprising:
- supplying an aqueous urea solution at a preset pressure of at least about 50 psi into a vessel having an inlet and an outlet;
- heating the urea solution in the vessel at a temperature above the hydrolysis temperature for the urea solution to produce an ammonia-containing gas;
- responsive to control signals related to engine load and temperature measured within the exhaust gas passage, introducing the ammonia-containing gas from said vessel into the exhaust passage wherein exhaust from said engine is measured to have an exhaust gas temperature effective for selective catalytic reduction;
- and
- passing the exhaust gas containing ammonia through an SCR reactor.
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 an SCR reactor effective for selective catalytic NOx reduction, comprising:
- means for supplying an aqueous urea solution at a preset pressure of from about 50 to 600 psi into a vessel having an inlet and an outlet;
- means for heating the urea solution in the vessel at a temperature above the hydrolysis temperature for the urea solution to produce ammonia;
- means for controlling introduction of ammonia from the vessel;
- means for introducing the ammonia into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction;
- and
- means for passing the exhaust gas containing the ammonia through an SCR reactor.
Dependencies are inferred from the claim text.