Method And Apparatus For Regenerating NOx Adsorbers

Abstract

In a method of regenerating a NOx adsorber, the NOx adsorber is used to treat exhaust gases created during the combustion of gaseous fuels in general. Methane is introduced into a reformer or exhaust line in which hydrogen generated during reforming is used to regenerate the NOx absorber.

1 . A method for regenerating a NOx adsorber used to remove NOx from exhaust gases generated by combustion of a fuel in a combustion chamber of an internal combustion engine, the method comprising:
 (a) carrying said exhaust gases from said combustion chamber to an exhaust line;   (b) reducing an oxygen concentration of a quantity of exhaust gases;   (c) creating a regeneration mix comprising:
 (1) said quantity of exhaust gases; and 
 (2) hydrogen and carbon monoxide reformed from a first quantity of a gaseous hydrocarbon; 
   (d) directing the regeneration mix into the NOx adsorber to regenerate the NOx adsorber;   
     wherein said quantity of exhaust gases is introduced in the reforming process of said first quantity of the gaseous hydrocarbon. 
   
   
       2 . The method of  claim 1  wherein the gaseous hydrocarbon comprises methane. 
   
   
       3 . The method of  claim 2  wherein said hydrogen and carbon monoxide are reformed in an exhaust gas environment. 
   
   
       4 . The method of  claim 2  further comprising oxidizing a second quantity of methane to reduce the oxygen concentration of the quantity of exhaust gases. 
   
   
       5 . The method of  claim 4  further comprising oxidizing hydrogen to reduce the oxygen concentration of the quantity of exhaust gases. 
   
   
       6 . The method of  claim 4  wherein the first quantity of methane comprises a residual unoxidized portion of the second quantity of methane. 
   
   
       7 . The method of  claim 2  wherein creating the regeneration mix occurs within the exhaust line. 
   
   
       8 . The method of  claim 2  further comprising reforming the first quantity of methane off-line. 
   
   
       9 . The method of  claim 2  further comprising heating the first quantity of methane prior to reforming the first quantity of methane. 
   
   
       10 . The method of  claim 9  wherein the heating is performed by operating a heater. 
   
   
       11 . The method of  claim 9  wherein the heating is performed by permitting heat exchange with the exhaust gases. 
   
   
       12 . The method of  claim 4  further comprising heating the second quantity of methane by oxidation of hydrogen whereby oxidation of the second quantity of methane is initiated. 
   
   
       13 . The method of  claim 2  further comprising by-passing a second quantity of exhaust gas around the NOx adsorber during a regeneration cycle. 
   
   
       14 . The method of  claim 13  further comprising utilizing emissions gas recirculation during the regeneration cycle. 
   
   
       15 . The method of  claim 13  further comprising warming an oxidizer prior to commencement of the regeneration cycle by directing a third quantity of methane into the oxidizer. 
   
   
       16 . An aftertreatment system for treating NOx within exhaust gases produced during combustion of a fuel within a combustion chamber of an internal combustion engine system, the aftertreatment system comprising:
 (a) an exhaust line connected to carry exhaust gases from the combustion chamber to a NOx adsorber;   (b) an oxidizer connectable to receive a first quantity of exhaust gases at a location downstream of the combustion chamber and upstream of the NOx adsorber, the oxidizer reducing an oxygen concentration of the first quantity of the exhaust gases;   (c) a reformer upstream of the NOx adsorber, the reformer generating hydrogen from a gaseous hydrocarbon;   (d) a first gas line connected to deliver to the reformer a first quantity of the gaseous hydrocarbon from a gaseous hydrocarbon store; and   (e) a regeneration line directing a regeneration mix to a location in the exhaust line upstream of the NOx adsorber, the regeneration mix comprising the hydrogen and the carbon monoxide from the reformer and the first quantity of exhaust gases from the oxidizer   
     wherein the reformer is disposed upstream of the NOx adsorber and downstream of the oxidizer such that an output of the oxidizer is connected to an input of the reformer and on output of the reformer is connected to the regeneration line. 
   
   
       17 . (canceled) 
   
   
       18 . The aftertreatment system of  claim 16  wherein the gaseous hydrocarbon comprises methane. 
   
   
       19 . (canceled) 
   
   
       20 . The aftertreatment system of  claim 16  wherein the reformer and the oxidizer are combined into a partial oxidation catalyst. 
   
   
       21 . The aftertreatment system of  claim 20  wherein the oxidation catalyst comprises a metal substrate. 
   
   
       22 . The aftertreatment system of  claim 20  wherein the first quantity of methane is a residual quantity of the second quantity of methane not consumed in the oxidation catalyst. 
   
   
       23 . The aftertreatment system of  claim 22  wherein the oxidation catalyst comprises a metal substrate. 
   
   
       24 . The aftertreatment system of  claim 20  wherein the oxidizer comprises a methane oxidation catalyst, wherein the first gas line is connected to direct a second quantity of methane to the oxidation catalyst. 
   
   
       25 . The aftertreatment system of  claim 24  wherein the oxidation catalyst comprises a metal substrate. 
   
   
       26 . The aftertreatment system of  claim 25  wherein the first quantity of methane is a residual quantity of the second quantity of methane not consumed in the oxidation catalyst. 
   
   
       27 . The aftertreatment system of  claim 26  wherein the oxidation catalyst comprises a metal substrate. 
   
   
       28 . The aftertreatment system of  claim 27  further comprising a second gas line connected to deliver the second quantity of methane to the oxidation catalyst. 
   
   
       29 . The aftertreatment system of  claim 28  wherein the oxidation catalyst comprises a metal substrate. 
   
   
       30 . The aftertreatment system of  claim 18  further comprising a heat exchanger for transferring heat from the exhaust gases to the reformer. 
   
   
       31 . The aftertreatment system of  claim 18  further comprising a heater for heating the reformer. 
   
   
       32 . The aftertreatment system of  claim 18  further comprising a heater for heating at least one of the reformer and the first quantity of the exhaust gases upstream of the oxidizer. 
   
   
       33 . The aftertreatment system of  claim 18  wherein the reformer is off-line, and the aftertreatment system comprises: a heater for heating at least one of a second oxidizer and a quantity of air, and an air line directing the heated air to the reformer. 
   
   
       34 . The aftertreatment system of  claim 33  wherein the second oxidizer and the reformer are combined in a partial oxidation catalyst. 
   
   
       35 . The aftertreatment system of  claim 33  wherein the first gas line is connected to introduce a second quantity of methane into the air line upstream of the oxidation catalyst. 
   
   
       36 . The aftertreatment system of  claim 33  wherein the heated second oxidizer oxidizes methane in the air, the first gas line directing the methane to the second oxidizer. 
   
   
       37 . The aftertreatment system of  claim 33  further comprising a second gas line connected to direct a second quantity of methane from the hydrocarbon store to the air line downstream of the oxidizer and upstream of the reformer. 
   
   
       38 . The aftertreatment system of  claim 18  further comprising a by-pass line for directing a second quantity of exhaust gas around the NOx adsorber. 
   
   
       39 . The aftertreatment system of  claim 18  wherein the fuel is a gaseous fuel. 
   
   
       40 - 46 . (canceled)