Eaton Corporation

International Engine Intellectual Property Company, LLC

Jiyang Yan

James Edward McCarthy, Jr

Haoran Hu

Karen Evelyn Bevan

Johannes Walter Reuter

Subbaraya Radhamohan

Dmitry Arie Shamis

David Yee

Vishal Singh

A diesel exhaust aftertreatment system comprises an LNT within an exhaust line. A low thermal mass DPF and a low thermal mass fuel reformer are configured within the exhaust line upstream from the LNT. A thermal mass is configured downstream from the fuel reformer and the DPF, but upstream from the LNT. For LNT denitration, the fuel reformer is rapidly heated and then used to catalyze steam reforming. The DPF is also rapidly heat each time the fuel reformer is heated and the LNT denitrated. The system operates to regenerate the DPF each time the LNT is denitrated. Preferably, a second DPF is provided to augment the performance of the first DPF. Preferably, the first DPF is small and of the flow through type whereas the second DPF is much larger and of the wall flow filter type. The second DPF can be used as the thermal mass.

System and method for coupled DPF regeneration and LNT DeNOx

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.

LNT regeneration strategy to reduce NOx spike

A power generation system comprises a diesel engine, a diesel particulate filter and a LNT configured to receive the exhaust from the DPF. The DPF is provided with a catalyst coating that is functional to catalyze methanation of trapped soot with Hcontained in the exhaust. Preferably, the catalyst has little or no oxygen storage capacity. The system is configured to regenerate the LNT by providing syn gas to the exhaust in rich regeneration phases. The syn gas-containing exhaust passes through the DPF and then the LNT. Within the DPF, the syn gas-containing exhaust removes soot be methanation and other soot gasification reactions, thus reducing or eliminating the need to reduce the DPF by other means. Soot gasification is preferred over soot combustion in that soot gasification avoids the destructive high DPF temperatures associated with soot combustion.

Gasification of soot trapped in a particulate filter under reducing conditions

An exhaust aftertreatment system including a lean NOx trap, an ammonia-SCR catalyst, and an additional catalyst configured in between. The lean NOx trap adsorbs NOx from lean exhaust and produces ammonia during regeneration. The SCR catalyst adsorbs most of that ammonia and subsequently uses that ammonia to reduce NOx. The additional catalyst is adapted to reduce the concentration of hydrocarbons in the exhaust during LNT regeneration and thereby mitigate hydrocarbon poisoning of the SCR. In one embodiment, the additional catalyst is a hydrocarbon-SCR catalyst. In another embodiment, the additional catalyst is an oxidation Catalyst. In a further embodiment, the additional catalyst is a hydrocarbon adsorbent. An oxidation catalyst can be made to store oxygen for hydrocarbon oxidation while avoiding excessive oxidation of ammonia by appropriately limiting that oxygen storage capacity.

Enhanced hybrid de-NOx system

A method of operating a power generation system involves operating a diesel engine to produce exhaust that is passed first through a combined DPF-fuel reformer and then a LNT. In response to the control signal to regenerate the LNT, fuel is injected into the exhaust at a rate that leaves the exhaust lean, whereby the injected fuel combusts in the combined DPF-reformer, warming it. There follows a rich phase in which fuel is injected into the exhaust at a rate that leaves the exhaust rich, whereby the DPF-reformer produces reformate and the LNT is regenerated. The combined DPF-reformer undergoes a regeneration that removes accumulated particulate matter with each LNT regeneration. Preferably, the DPF-reformer has a low thermal mass to facilitate heating. Preferably, the DPF-reformer includes a soot gasification catalyst, whereby a substantial amount of particulate matter is removed from the DPF-reformer during the rich phases.

Integrated DPF-reformer

An exhaust aftertreatment system comprising two or more branches, at least one of which contains a NOx adsorber-catalyst. The branches unite downstream into a trailing conduit that contains an ammonia-SCR catalyst. Ammonia generated by the NOx adsorber-catalyst during regeneration is stored for later use by the SCR catalyst. One advantage of this configuration is a continuous or near continuous presence of oxygen within the trailing exhaust conduit. The continuous presence of improves the efficiency of the SCR catalyst. Another concept is to configure a multi-branch exhaust aftertreatment system without valves, dampers, or other electronically controlled devices adapted to selectively alter the distribution of the exhaust between the branches. The absence of such devices generally results in a comparatively balanced division of exhaust between the branches. One benefit of this configuration is improved reliability as compared to systems that use valves.

Valveless dual leg exhaust aftertreatment system

In an exhaust aftertreatment system comprising a NOx adsorber-catalyst followed by an SCR catalyst, means are provided for preventing the SCR catalyst from becoming heated to near the same peak temperatures as the NOx adsorber-catalyst during desulfation. In one embodiment, the means is a thermal mass between the NOx adsorber-catalyst and the SCR catalyst. In another embodiment, the means is a valve configured to selectively divert exhaust leaving the NOx adsorber-catalyst from the SCR catalyst. In a method of the invention, the NOx adsorber-catalyst temperature is cycled during desulfation. The peaks of the cycles are within an appropriate temperature range for desulfating the NOx adsorber-catalyst, but the average temperature is below the temperature range at which the SCR catalyst is damaged. The temperature peaks are damped as they travel from the NOx adsorber-catalyst to the SCR, whereby the SCR experiences much lower peak temperatures than the NOx adsorber-catalyst.

Thermal management of hybrid LNT/SCR aftertreatment during desulfation

The invention relates to a power generation system with a continuously operating fuel reformer. Preferably, the fuel reformer is either off, warming up, or operating with an essentially constant fueling rate. Some of the reformed fuel is intermittently used to regenerate a NOx trap that treats the exhaust of an internal combustion engine. Any reformed fuel not used for other purposes is supplied to a fuel cell. The fuel reformer does not shut down between NOx trap regeneration cycles except when the engine is also shut down. The invention substantially eliminates issues of reformer response time as they relate to NOx trap regeneration.

Growing community of inventors

Troy, MI, United States of America

Jiyang Yan