Systems and methods are disclosed for ameliorating NOx slip from a lean NOx trap by reducing the amount of hydrocarbons reaching the lean NOx trap during the early stages of, or in a period immediately preceding, a rich regeneration. In one embodiment, a hydrocarbon absorber is configured downstream
Systems and methods are disclosed for ameliorating NOx slip from a lean NOx trap by reducing the amount of hydrocarbons reaching the lean NOx trap during the early stages of, or in a period immediately preceding, a rich regeneration. In one embodiment, a hydrocarbon absorber is configured downstream from a fuel reformer, but upstream from the lean NOx trap, in order to reduce the quantity of hydrocarbons that reach the lean NOx trap during lean reformer warm-up and rich regeneration phases. In another embodiment, the fueling rate to a fuel reformer configured in an exhaust line upstream from the lean NOx trap is limited to reduce NOx slip.
대표청구항▼
The invention claimed is: 1. A method of operating a power generation system, comprising: operating a diesel engine to produce exhaust comprising NOx; passing at least a portion of the exhaust from the engine to a lean NOx trap through a fuel reformer; adsorbing NOx from the exhaust under lean cond
The invention claimed is: 1. A method of operating a power generation system, comprising: operating a diesel engine to produce exhaust comprising NOx; passing at least a portion of the exhaust from the engine to a lean NOx trap through a fuel reformer; adsorbing NOx from the exhaust under lean conditions using the lean NOx trap; preparing to regenerate the lean NOx trap by heating the fuel reformer by at least 100° C. to a temperature of at least about 500° C. by injecting fuel at rates that leave the exhaust entering the fuel reformer lean, while at times limiting the fuel injection rates to limit the amount of NOx that slips from the lean NOx trap; and wherein limiting the fuel injection rates to limit the amount of NOx that slips from the lean NOx trap comprises either: (a) setting the fuel injection rate to an upper limit determined by a relationship between fuel injection rate and hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap; or (b) adjusting the fuel injection rate based on measurements of hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 2. The method of claim 1, wherein so limiting the fuel injection rate limits the reformer heating rate to about 50° C. per second or less. 3. The method of claim 1, wherein so limiting the fuel injection rate limits the reformer heating rate to about 20° C. per second or less. 4. The method of claim 1, wherein so limiting the fuel injection rates comprises setting the fuel injection rate to an upper limit determined by a relationship between fuel injection rate and hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 5. The method of claim 1,wherein so limiting the fuel injection rates comprises adjusting the fuel injection rate based on measurements of hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 6. The method of claim 1, wherein the fuel injection rate limits increase based on increasing lean NOx trap temperature. 7. The method of claim 1, further comprising, while heating the fuel reformer, adsorbing hydrocarbons slipping from the fuel reformer using a hydrocarbon absorber positioned upstream from the lean NOx trap. 8. The method of claim 1, further comprising passing the exhaust from the lean NOx trap to a ammonia-selective catalytic reduction catalyst. 9. A method of operating a power generation system, comprising: operating a diesel engine to produce exhaust comprising NOx; passing at least a portion of the exhaust from the engine to a lean NOx trap through a fuel reformer; using the lean NOx trap, adsorbing NOx from the exhaust under lean conditions; and injecting fuel at rates that leave the exhaust entering the fuel reformer rich, whereby the fuel reformer produces syn gas that regenerates the lean NOx trap, wherein the fuel injection rates are at times limited to limit the amount of NOx that slips from the lean NOx trap; wherein limiting the fuel injection rates to limit the amount of NOx that slips from the lean NOx trap comprises either: (a) setting the fuel injection rate to an upper limit determined by a relationship between fuel injection rate and hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap; or (b) adjusting the fuel injection rate based on measurements of hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 10. The method of claim 9, further comprising preparing to regenerate the lean NOx trap by heating the fuel reformer by at least 100° C. to a temperature of at least about 500° C. by injecting fuel at rates that leave the exhaust entering the fuel reformer lean. 11. The method of claim 9, wherein so limiting the fuel injection rates comprises setting the fuel injection rate to an upper limit determined by a relationship between fuel injection rate and hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 12. The method of claim 9, wherein so limiting the fuel injection rates comprises adjusting the fuel injection rate based on measurements of hydrocarbon slip from the fuel reformer or NOx slip from the lean NOx trap. 13. The method of claim 9, wherein the fuel injection rate limits increase based on increasing lean NOx trap temperature. 14. The method of claim 9, further comprising, while regenerating the lean NOx trap, adsorbing hydrocarbons slipping from the fuel reformer using a hydrocarbon absorber positioned upstream from the lean NOx trap. 15. The method of claim 9, further comprising passing the exhaust from the lean NOx trap to a ammonia-selective catalytic reduction catalyst.
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이 특허에 인용된 특허 (20)
Taylor, III, William; Crane, Jr., Samuel N.; Kong, Yougen, Apparatus and method for operating a fuel reformer to regenerate a DPNR device.
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