Fuel Reformer for De-NOx Trap

Patent metadata

Field	Value
Publication number	US-2016199782-A1
Application number	US-201514593340-A
Country	US
Kind code	A1
Filing date	Jan 9, 2015
Priority date	Jan 9, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

An emissions control system for an engine of a machine includes an exhaust conduit carrying a flow of exhaust gas from the engine, a de-NOx catalyst disposed along the exhaust conduit and configured to treat the flow of exhaust gas, a fuel reformer module configured to provide a gas stream containing hydrogen gas and carbon monoxide gas, and a junction disposed along the exhaust conduit between the engine and the de-NOx catalyst, the junction being arranged to mix at least a portion of the gas stream with the flow of exhaust gas such that the hydrogen gas and the carbon monoxide reach the de-NOx catalyst and act as reductants to regenerate the de-NOx trap.

First claim

We claim:

1 . An emissions control system for an engine of a machine, comprising:
an exhaust conduit carrying a flow of exhaust gas from the engine; a de-NOx catalyst disposed along the exhaust conduit and configured to treat the flow of exhaust gas; a fuel reformer module configured to provide a gas stream containing hydrogen gas and carbon monoxide gas; and a junction disposed along the exhaust conduit between the engine and the de-NOx catalyst, the junction being arranged to mix at least a portion of the gas stream with the flow of exhaust gas such that the hydrogen gas and the carbon monoxide reach the de-NOx catalyst and act as reductants to regenerate the de-NOx catalyst.

2 . The emissions control system of claim 1 , wherein the junction is a valve configured to selectively control a flow rate of the gas stream into the exhaust conduit.

3 . The emissions control system of claim 1 , wherein the fuel reformer module comprises a heat exchanger that is connected to an air source, a water source, and the flow of exhaust gas, the heat exchanger operating to remove heat from the flow of exhaust gas and provide the removed heat to heat air and water provided to the heat exchanger from, respectively, the air source and the water source.

4 . The emissions control system of claim 3 , wherein the fuel reformer module further comprises an auto-thermal reformer (ATR) connected to a fuel source and to the heat exchanger, the ATR operating to at least partially and at least incompletely oxidize methane provided from the fuel source with air provided from the heat exchanger according to the reaction equation:
4CH4+02+2H2O=>10H2+4CO.

5 . The emissions control system of claim 4 , wherein an outlet of the ATR is disposed within a cavity of a steam reformer such that an effluent gas product of the ATR is fluidly provided directly into the cavity of the steam reformer.

6 . The emissions control system of claim 5 , wherein the cavity is fluidly connected to the fuel source and the water source via dedicated valves, each configured to selectively control an amount of fuel and water provided to the cavity of the steam reformer.

7 . The emissions control system of claim 6 , wherein the steam reformer operates to carry out the following chemical reactions using the effluent gas, water, and methane from the fuel source:
CH4+H20=>3H2+CO; and CO+H20=>H2+C02.

8 . The emission control system of claim 7 , wherein the steam reformer produces the gas stream that is provided to the junction.

9 . The emissions control system of claim 6 , wherein the cavity of the steam reformer has a generally cylindrical shape, and wherein water is provided to the cavity through a ring-shaped water injector.

10 . The emissions control system of claim 3 , wherein the heat exchanger is constructed as an enclosed section of the exhaust conduit into which water and fuel are injected.

11 . A fuel reformer, comprising:
an outer shell having an open end and a closed end, the outer shell having a substantially cylindrical shape that defines a cavity therein and extends along a centerline; a tube having an open end and a closed end, the tube disposed concentrically relative to the outer shell along the centerline such that the open end of the tube is facing the closed end of the outer shell, wherein at least a portion of an outer surface of the tube is coated with a catalyst; a first fuel conduit fluidly connected to an interior of the tube; a steam conduit fluidly connected to the interior of the tube; a second fuel conduit fluidly connected to the cavity of the outer shell; and a water conduit connected to a water injector disposed within the cavity of the outer shell; wherein, during operation, the interior of the tube operates as an auto-thermal reformer (ATR) that partially oxidizes fuel provided through the first fuel conduit; and wherein, during operation, the cavity operates as a steam reformer that strips hydrogen from hydrocarbons provided through the second fuel conduit by using steam created by water provided through the water injector and heat provided by an effluent gas from the ATR.

12 . The fuel reformer of claim 11 , wherein the steam reformer provides a gas stream that includes hydrogen gas and carbon monoxide, the carbon monoxide having a concentration greater than 10 ppm.

13 . The fuel reformer of claim 11 , wherein the ATR carries out a chemical reaction according to the following reaction equation:
4CH4+02+2H2O=>10H2+4CO.

14 . The fuel reformer of claim 11 , wherein the steam reformer carries out the following chemical reactions:
CH4+H20=>3H2+CO; and CO+H20=>H2+C02.

15 . A method for abating NOx in an exhaust flow of an internal combustion engine, comprising:
providing a gaseous fuel to an auto-thermal reformer (ATR), which is configured to at least partially oxidize the gaseous fuel; providing air and water to a heat exchanger to produce steam and warmed air in the heat exchanger; providing the steam and warmed air to the ATR at a controlled temperature; providing an effluent gas from the ATR into a steam reformer; further providing an additional amount of gaseous fuel and water to the steam reformer; carrying out chemical reactions in the steam reformer to produce a gas stream including hydrogen and carbon monoxide; mixing the gas stream with the exhaust flow of the internal combustion engine at a location upstream of a de-NOx catalyst; and using the hydrogen gas and carbon monoxide as reductants for regenerating the de-NOx catalyst.

16 . The method of claim 15 , the carbon monoxide in the gas stream has a concentration greater than 10 ppm.

17 . The method of claim 15 , wherein the ATR carries out a chemical reaction according to the following reaction equation:
4CH4+02+2H2O=>10H2+4CO.

18 . The method of claim 15 , wherein the steam reformer carries out the following chemical reactions:
CH4+H20=>3H2+CO; and CO+H20=>H2+C02.

19 . The method of claim 15 , wherein the internal combustion engine operates on the gaseous fuel as a primary fuel source.

20 . The method of claim 15 , wherein providing an additional amount of water to the steam reformer includes injecting water from a ring injector disposed within a cylindrical cavity of the steam reformer, the cylindrical cavity surrounding the ATR, which has a tubular shape and is disposed within the cavity of the steam reformer.

Assignees

• Caterpillar Inc

Inventors

• Ge Xinyu

Classifications

• B01D2251/202

  Hydrogen · CPC title

• B01D53/9422 Primary

  for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR) · CPC title

• B01D2251/204

  Carbon monoxide · CPC title

• F01N3/2066

  Selective catalytic reduction [SCR] · CPC title

• B01D53/9431 Primary

  Processes characterised by a specific device · CPC title