Bypass controlled regeneration of NOx adsorbers

US20050223699A1Inactive Publication Date: 2005-10-13WESTPORT POWER
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2005-10-13
Estimated Expiration
Not applicable · inactive patent

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Abstract

In a method and apparatus for regenerating a lean NOx adsorber, the NOx adsorber treats exhaust gases created during the combustion of gaseous fuels in general. A bypass line maintains a target regeneration flow of exhaust gas through the NOx adsorber during regeneration regardless of operating demands on the engine. Closed-loop and open-loop control are employed. The closed-loop control employs sensors that determine properties of the exhaust gas during regeneration, and the controller uses those properties to provide an efficient regeneration cycle. A regeneration map is also provided that uses creation of in-cylinder regeneration conditions for the exhaust gas in combination with in-line regeneration conditions for the exhaust gas.
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Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application is a continuation of International Application No. PCT / CA2003 / 001467, having an international filing date of Oct. 2, 2003, entitled “Bypass Controlled Regeneration Of NOx Adsorbers”. International Application No. PCT / CA2003 / 001467 claimed priority benefits, in turn, from Canadian Patent Application No. 2,406,386 filed Oct. 2, 2002, and Canadian Patent Application No. 2,422,188 filed Mar. 14, 2003. International Application No. PCT / CA2003 / 001467 is also hereby incorporated by reference herein in its entirety.FIELD OF THE INVENTION

[0002] This invention relates to methods and apparatus for regenerating NOx absorbers used in association with internal combustion engines. BACKGROUND OF THE INVENTION

[0003] Emissions controls for internal combustion engines are becoming increasingly important in transportation and energy applications. One class of pollutants of concern is oxides of nitrogen (NOx). NOx form during combustion...

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Embodiment Construction

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[0090] A method of regenerating a NOx adsorber that is used to treat exhaust gases created during combustion in the combustion chamber is disclosed. A hydrocarbon, preferably methane, is introduced into the exhaust line wherein the hydrocarbon is oxidized and reformed within the exhaust line to generate hydrogen, which is used to regenerate the NOx absorber. CO, as well as hydrogen, is generated during reformation of methane resulting in a regeneration mixture that includes both hydrogen and CO. The aftertreatment system is capable of directing an amount of exhaust gas to by-pass the NOx adsorber during regeneration for the purposes of reducing regeneration flow, hydrocarbon consumption, emissions, and regeneration time. Specific markers, indicative of the properties of the exhaust gas, can be used to identify completion of regeneration.

[0091]FIG. 1 is a schematic showing an aftertreatment system according to a preferred embodiment of the invention. An exhaust line 22 carries exha...