Patent ID: 8209960

Claim:
A method of operating a diesel power generation system, comprising: operating a compression ignition diesel engine to produce a lean exhaust comprising NO X and particulate matter; treating the exhaust by passing it through a fuel reformer, a first DPF, a thermal mass, and a lean NO X trap (LNT), whereby the LNT traps a portion of the NO X and the first DPF traps a portion of the particulate matter; determining when to denitrate the LNT; in response to the determination, injecting fuel into the exhaust at a rate that leaves the exhaust lean, whereby the injected fuel combusts, the fuel reformer heats to steam reforming temperatures, and the first DPF also heats; after heating the fuel reformer to steam reforming temperatures, denitrating the LNT by making the exhaust entering the fuel reformer, the first DPF, and the lean NO X trap rich, whereby the fuel reformer produces reformate that denitrates the LNT; and in conjunction with the foregoing steps of heating the fuel reformer and denitrating the LNT, heating the first DPF to soot combustion temperatures, whereby the first DPF is regenerated each time the LNT is denitrated; wherein the first DPF is functional to filter a substantial portion of the particulate matter from the exhaust and has a low thermal mass that facilitates the first DPF being heated to soot combustion temperatures each time the LNT is denitrated; wherein the fuel reformer comprises a steam reforming catalyst and has a low thermal mass that facilitates its being heated to steam reforming temperatures for each LNT denitration; wherein the LNT is functional to absorb and store NO X under lean conditions and reduce the stored NO X and regenerate under rich conditions; and the thermal mass is functional to substantially reduce the temperatures to which the LNT is heated during the fuel reformer heating and LNT denitration.