Enhanced aftertreatment apparatus regeneration using spatially controlled hydrogen-rich gas

Abstract

Regeneration system in which a hydrogen-rich gas from an onboard reformer flows into an aftertreatment unit in a direction opposite to the flow of engine exhaust to regenerate the unit. The aftertreatment unit is segmented with independent regeneration capability for each segment. Regeneration is performed with hydrogen-rich gas produced by an onboard reformer. A hydrogen-rich gas switchbox is used to direct the flow of the reformate to the segment of the aftertreatment unit that is undergoing regeneration.

1 ) Regeneration system comprising:
 an exhaust aftertreatment unit fitted to the exhaust of an internal combustion engine; and   a fuel reformer providing hydrogen-rich gas to the aftertreatment unit so as to obtain spatially selective regeneration of the aftertreatment unit; and   including a hydrogen-rich gas switchbox having associated valves and plumbing for controlling the flow of hydrogen-rich gas, wherein the valves in the switchbox are used to direct the flow of hydrogen-rich gas to the appropriate plumbing to regenerate the associated section of the aftertreatment unit.   
     
     
         2 ) Regeneration system comprising:
 an exhaust aftertreatment unit fitted to the exhaust of an internal combustion engine; and   a fuel reformer providing hydrogen-rich gas to the aftertreatment unit so as to obtain spatially selective regeneration of the aftertreatment unit wherein the engine exhaust is prevented from flowing in the region being regenerated by the hydrogen-rich gas flowing in an opposite direction to the exhaust flow.   
     
     
         3 ) The regeneration system of  claims 1  or  2  wherein the aftertreatment unit is segmented in sections that undergo independent regeneration. 
     
     
         4 ) The system of  claims 1  or  2  wherein the aftertreatment device is a NOx trap. 
     
     
         5 ) The system of  claims 1  or  2  wherein the aftertreatment device is a diesel particulate filter. 
     
     
         6 ) The system of  claim 2  further including a hydrogen-rich gas switchbox having associated valves and plumbing for controlling the flow of hydrogen-rich gas, wherein the valves in the switchbox are used to direct the flow of hydrogen-rich gas to the appropriate plumbing to regenerate the associated section of the aftertreatment unit. 
     
     
         7 ) The system of  claim 6  wherein the valves are butterfly valves. 
     
     
         8 ) The system of  claim 6  wherein the valves are poppet valves. 
     
     
         9 ) The system of  claims 7  or  8  wherein the valves are actuated by either vacuum or compressed air. 
     
     
         10 ) The system of  claim 6  wherein the valves are sleeve valves. 
     
     
         11 ) The system of  claim 10  wherein the sleeve valve is made of flat surfaces, the moving part having one or more openings. 
     
     
         12 ) The system of  claim 11  wherein the sleeve valve surfaces are cylindrical shells with the moving part having one or more openings. 
     
     
         13 ) The system of  claim 11  wherein the moving part is driven by an electromagnetic actuator. 
     
     
         14 ) The system of  claim 5  wherein, during switching, there are two or more partially or fully open valves. 
     
     
         15 ) The system of  claims 1  or  2  further including at least one regeneration sensor located upstream from the exhaust system, the sensor or sensors monitoring either reformate compounds or regeneration compounds. 
     
     
         16 ) The system of  claims 1  or  2  wherein the fuel reformer operates over a wide range of oxygen-to-carbon ratios, from below partial oxidation to below full combustion. 
     
     
         17 ) The system of  claims 1  or  2  wherein there is a heat exchanger downstream from the reformer but upstream from the aftertreatment unit. 
     
     
         18 ) The system of  claim 4  wherein there is ammonia generated in the region that is being regenerated by the hydrogen rich gas, the ammonia re-entering other regions of the NOx trap that are not being regenerated by the hydrogen rich gas. 
     
     
         19 ) The system of  claims 1  or  2  wherein a lean NOx catalyst and an SCR catalyst are both used and where the SCR catalyst is closer to the engine, so that the hydrogen rich gas passes over the lean NOx catalyst before it reaches the SCR catalyst. 
     
     
         20 ) The system of  claims 1  or  2  wherein the fuel reformer is a plasmatron fuel reformer.