Impactor for selective catalytic reduction system
AssigneeFleetguard, Inc.
InventorsBarry M. Verdegan, Z. Gerald Liu
Life of this patent
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Abstract
A selective catalytic reduction system for engine exhaust injects a solution comprising a source of ammonia, preferably an aqueous urea solution, or other ammonia solution, to preferably evaporate, decompose and hydrolyze to produce ammonia to react with and reduce NOx in the exhaust. An inertial impactor in the housing between the injector and the catalyst is impacted by the solution droplets and holds same until evaporated, decomposed and hydrolyzed to ammonia.
Claims11
A selective catalytic reduction device for engine exhaust comprising:
- a housing having an upstream inlet for receiving said exhaust, and a downstream outlet for discharging said exhaust;
- an injector in said housing for injecting a solution comprising a source of ammonia to react with and reduce NOx in said exhaust;
- a catalyst in said housing downstream of said injector;
- an inertial impactor in said housing between said injector and said catalyst and impacted by said exhaust and said solution, wherein said impactor holds said solution to enhance ammonia reaction with NOx, said impactor is nonporous, and wherein said impactor and the injection rate from said injector are selected to satisfy the following condition:
- the solution evaporation rate at said impactor is greater than the injection rate at said injector.
A selective catalytic reduction device for engine exhaust comprising:
- a housing having an upstream inlet for receiving said exhaust, and a downstream outlet for discharging said exhaust;
- an injector in said housing for injecting a solution comprising a source of ammonia to react with and reduce NOx in said exhaust;
- a catalyst in said housing downstream of said injector;
- an inertial impactor in said housing between said injector and said catalyst and impacted by said exhaust and said solution, wherein said impactor holds said solution to enhance ammonia reaction with NOx, and said impactor has a star shape with a central core and a plurality of radially outwardly projecting tips each providing impaction surface area yet permitting exhaust flow therebetween.
A method for enhancing ammonia reaction with NOx in a selective catalytic reduction device for engine exhaust having a housing with an upstream inlet for receiving said exhaust, and a downstream outlet for discharging said exhaust, comprising injecting a solution comprising a source of ammonia in said housing with an injector to react with and reduce NOx in said exhaust, providing a catalyst in said housing downstream of said injector, inertially impacting said exhaust and said solution against an inertial impactor in said housing between said injector and said catalyst, and comprising holding said solution at said impactor to enhance ammonia reaction with NOx, and providing a nonporous said impactor, and injecting said solution from said injector at an injection rate less than the solution evaporation rate at said impactor.
A selective catalytic reduction device for engine exhaust comprising:
- a housing having an upstream inlet for receiving said exhaust, and a downstream outlet for discharging said exhaust;
- an injector in said housing for injecting an aqueous urea solution which evaporates, decomposes and hydrolyzes to produce ammonia to react with and reduce NOx in said exhaust;
- an SCR catalyst in said housing downstream of said injector;
- an impactor in said housing and spaced downstream from said injector and spaced upstream from said SCR catalyst, said impactor comprising a hydrolysis catalyst facilitating decomposition and hydrolysis of said aqueous urea solution at said impactor, wherein said housing extends axially along an axis and exhaust flows generally axially through said housing, said aqueous urea solution is injected along an injection spray angle θ from said injector, said hydrolysis catalyst has a lateral cross-sectional dimension D transverse to said axis, said injector has a downstream injection tip spaced from said hydrolysis catalyst by a distance d along said axis and having an inner diameter φ transverse to said axis, and wherein D>2d tan(θ/2)+φ.
Dependencies are inferred from the claim text.