DIESEL AFTERTREATMENT SYSTEM
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 .