Diesel aftertreatment system

Abstract

A diesel exhaust gas aftertreatment system ( 10 ) is provided to treat the exhaust ( 12 ) from a diesel combustion process ( 14 ), such as a diesel compression engine ( 16 ). The system ( 10 ) includes a burner ( 18 ) that selectively supplies the exhaust ( 12 ) at an elevated temperature to the rest of the system ( 10 ), a diesel particulate filter ( 20 ) connected downstream from the burner ( 18 ) to receive the exhaust ( 12 ) therefrom, and a NO x reducing device ( 22 ) connected downstream from the filter ( 20 ) to receive the exhaust therefrom.

1 . A diesel exhaust gas treatment system to treat the exhaust from a diesel combustion process, the system comprising:
 a burner to receive the exhaust and selectively heat the exhaust with a flame to supply the exhaust at an elevated temperature to the rest of the system;   a diesel particulate filter connected downstream from the burner to receive the exhaust therefrom; and   at least one of a selective catalytic reduction catalyst and a NO x  trap connected downstream from the diesel particulate filters to receive the exhaust therefrom   
     
     
         2 . The system of  claim 1  further comprising a diesel oxidation catalyst connected downstream from the burner to receive the exhaust therefrom and upstream from the diesel particulate filters to deliver the exhaust thereto. 
     
     
         3 . The system of  claim 2  further comprising a diesel oxidation catalyst connected downstream from the diesel particulate filters to receive the exhaust therefrom and upstream from the selective catalytic reduction catalyst to deliver the exhaust thereto. 
     
     
         4 . The system of  claim 2  further comprising a fuel injector located downstream from the burner and upstream of the DOC. 
     
     
         5 . The system of  claim 1  wherein the burner comprises at least one fuel injector and at least one igniter. 
     
     
         6 . The system of  claim 1  wherein the at least one of a selective catalytic reduction catalyst and a NO x  trap is a selective catalytic reduction catalyst and further comprising a reductant injector connected upstream from the catalyst. 
     
     
         7 . A method of treating a diesel exhaust from a diesel combustion process, the method comprising the steps of:
 (a) selectively increasing the temperature of the exhaust by burning a fuel in the exhaust flow downstream from the diesel combustion process;   (b) removing soot from a filter by oxidizing carbon into the increased temperature exhaust provided from step (a); and   (c) removing NO x  carried in the exhaust provided from step (b).   
     
     
         8 . The method of  claim 7  further comprising the step of producing NO 2  by passing the exhaust from step (a) through an oxidation catalyst prior to step (b). 
     
     
         9 . The method of  claim 8  further comprising the step of producing NO 2  by passing the exhaust from step (b) through an oxidation catalyst prior to step (c). 
     
     
         10 . The method of  claim 8  further comprising the step of injecting fuel into the exhaust after step (a) and prior to step (b). 
     
     
         11 . The method of  claim 7  wherein step (a) comprises the steps of injecting a fuel into the exhaust and igniting the fuel. 
     
     
         12 . The method of  claim 7  wherein step (c) comprises converting NO x  to N 2  by passing the exhaust over a selective catalytic reduction catalyst. 
     
     
         13 . The method of  claim 7  wherein step (c) comprises trapping NO x .