Gaseous Fuel Spark-Ignited Internal Combustion Engine System

Abstract

A system and method for reforming a portion of an exhaust gas stream in an internal combustion engine system. An exhaust gas recirculation assembly divides the exhaust gas stream into a recycle stream and a vent stream. A mixer in fluid receiving communication with the recycle stream forms a combination stream by mixing a gaseous fuel stream with the recycle stream. A thermochemical recuperator component fluidly connects to the mixer and includes a first flow path and a second flow path. The first flow path has a catalyst through which the combination stream flows to create a reformate stream, and the second flow path has a heat transfer area for transferring heat from the vent stream to the combination stream.

1 . An engine system, comprising:
 an exhaust gas recirculation assembly fluidly connected to an exhaust manifold of an internal combustion engine, the exhaust gas recirculation assembly configured to divide an exhaust gas stream into a recycle stream and a vent stream;   a mixer in fluid receiving communication with the recycle stream, the mixer configured to form a combination stream by mixing a gaseous fuel stream with the recycle stream; and   a thermochemical recuperator component fluidly connected to the mixer, wherein the thermochemical recuperator including:
 a first flow path comprising a catalyst through which the combination stream flows to create a reformate stream, and 
 a second flow path comprising a heat transfer area for transferring heat from the vent stream to the combination stream. 
   
     
     
         2 . The engine system of  claim 1 , wherein the reformate stream comprises a hydrogen enriched gaseous stream. 
     
     
         3 . The engine system of  claim 1 , further comprising an exhaust gas aftertreatment sub-system fluidly connected between the exhaust manifold of an internal combustion engine and the exhaust gas recirculation assembly. 
     
     
         4 . The engine system of  claim 3 , wherein the exhaust gas aftertreatment sub-system includes a three-way catalyst. 
     
     
         5 . The engine system of  claim 1 , wherein the gaseous fuel stream comprises natural gas. 
     
     
         6 . The engine system of  claim 1 , further comprising a sulfur scrubber positioned upstream of the thermochemical recuperator component. 
     
     
         7 . The engine system of  claim 1 , further comprising a fuel pre-heater, the pre-heater configured to transfer heat from the vent stream to the gaseous fuel stream. 
     
     
         8 . The engine system of  claim 1 , further comprising a reformate stream cooler, the reformate stream cooler configured to lower the temperature of the reformate stream. 
     
     
         9 . The engine system of  claim 1 , further comprising a second mixer, the second mixer configured to combine the reformate stream with an air stream so as to form an intake stream for routing to the internal combustion engine. 
     
     
         10 . The engine system of  claim 1 , further comprising a filter disposed in the reformate stream, the filter configured to remove selected particulate matter from the reformate stream. 
     
     
         11 . The engine system of  claim 1 , further comprising a turbocharger with a turbine upstream of the exhaust gas recirculation assembly. 
     
     
         12 . An engine system, comprising
 a natural gas engine including an intake manifold and an exhaust manifold;   an exhaust gas recirculation assembly fluidly connected to the exhaust manifold, the exhaust gas recirculation assembly configured to divide an exhaust gas stream into a recycle stream and a vent stream;   a mixer in fluid receiving communication with the recycle stream, the mixer configured to form a combination stream by mixing the gaseous fuel stream with the recycle stream; and   a thermochemical recuperator component fluidly connected to the mixer, wherein the thermochemical recuperator comprises:
 a first flow path comprising a catalyst through which the combination stream flows to create a hydrogen-enriched reformate stream, and 
 a second flow path comprising a heat transfer area for transferring heat from the vent stream to the combination stream. 
   
     
     
         13 . The engine system of  claim 12 , further comprising a second mixer in fluid receiving communication with the reformate stream, the second mixer configured to form an intake stream by combining the reformate stream with an air stream. 
     
     
         14 . The engine system of  claim 12 , further comprising an exhaust gas aftertreatment sub-system fluidly connected between the exhaust manifold and the exhaust gas recirculation assembly. 
     
     
         15 . The engine system of  claim 14 , wherein the exhaust gas aftertreatment sub-system includes a three-way catalyst. 
     
     
         16 . The engine system of  claim 12 , further comprising a fuel pre-heater in fluid receiving communication with the vent stream and configured to transfer heat from the vent stream to a gaseous fuel stream; 
     
     
         17 . A method for reforming a portion of an exhaust gas stream, the method comprising:
 dividing the exhaust gas stream from an engine into a recycle stream and a vent stream;   mixing the recycle stream with a gaseous fuel stream to form a combination stream; and   catalytically converting the combination stream into a hydrogen-enriched reformate stream.   
     
     
         18 . The method of  claim 17 , wherein catalytically converting the combination stream into a hydrogen-enriched reformate stream includes flowing the combination stream through a first flow path of a thermochemical recuperator component and flowing the vent stream through a second flow path of the thermochemical recuperator component, wherein the first flow path comprises a catalyst for reacting the combination stream and the second flow path comprises a heat transfer area for transferring heat from the vent stream to the combination stream. 
     
     
         19 . The method of  claim 17 , further comprising pre-heating the gaseous fuel stream by transferring heat from the vent stream to the gaseous fuel stream. 
     
     
         20 . The method of  claim 17 , further comprising cooling the hydrogen-enriched reformate stream. 
     
     
         21 . The method of  claim 17 , further comprising removing oxygen from the exhaust gas stream before catalytically converting the combination stream into a hydrogen-enriched reformate stream. 
     
     
         22 . The method of  claim 21 , wherein removing oxygen from the exhaust gas stream comprises operating the engine at an air/fuel ratio that is one of stoichiometric and fuel rich. 
     
     
         23 . The method of  claim 21 , wherein a three-way catalyst is used in the removing of oxygen from the exhaust gas stream