Dual reaction zone fuel reformer and associated method

Abstract

An apparatus comprises a supplier of air and/or fuel, a main passageway fluidly coupled to the supplier to receive air and/or fuel therefrom to provide a fuel-rich air-and-fuel main mixture in the main passageway, and a pilot flame generator mounted in the main passageway. The pilot flame generator defines therein a pilot passageway that is fluidly coupled to the supplier to receive air and/or fuel therefrom and is fluidly coupled to the main passageway to receive air and/or fuel therefrom to provide an air-and-fuel pilot mixture in the pilot passageway. The pilot flame generator comprises an ignition device configured to ignite the pilot mixture to generate a pilot flame that initiates a partial oxidation reaction of the main mixture so as to generate reformate gas. An associated method is disclosed.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to methods and apparatus for reforming fuel.

BACKGROUND OF THE DISCLOSURE

Fuel reformers are used to reform fuel into a reformate gas such as hydrogen (H₂) or carbon monoxide (CO). Such reformate gas may be used for a variety of purposes such as hydrogen-enhancement of engine combustion, emission abatement, and fuel cell operation.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, there is provided an apparatus comprises a supplier of air and/or fuel, a main passageway fluidly coupled to the supplier to receive air and/or fuel therefrom to provide a fuel-rich air-and-fuel main mixture in the main passageway, and a pilot flame generator mounted in the main passageway. The pilot flame generator defines therein a pilot passageway that is fluidly coupled to the supplier to receive air and/or fuel therefrom and is fluidly coupled to the main passageway to receive air and/or fuel therefrom to provide an air-and-fuel pilot mixture in the pilot passageway. The pilot flame generator comprises an ignition device configured to ignite the pilot mixture to generate a pilot flame that initiates a partial oxidation reaction of the main mixture so as to generate reformate gas. An associated method is disclosed.

The above and other features of the present disclosure will become apparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an embodiment of a fuel reformer;

FIG. 2 is a diagrammatic view showing a bypass provided in conjunction with the fuel reformer of FIG. 1; and

FIG. 3 is a diagrammatic view showing another embodiment of a fuel reformer.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives following within the spirit and scope of the invention as defined by the appended claims.

Referring to FIG. 1, there is provided an apparatus 10 which has a fuel reformer 12 for reforming a fuel (e.g., diesel, gasoline) into reformate gas in the form of, for example, H₂ and/or CO for use by a reformats gas user 13. The reformate gas user 13 may be configured in a variety of ways including, but not limited to, a hydrogen-enhanced combustion engine, a fuel cell, and/or an emission abatement device (e.g., a NOx trap, a selective catalytic reduction catalyst, a catalyzed particulate filter, an oxidation catalyst in combination with a catalyzed or uncatalyzed particulate filter). The reformer 12 comprises a pilot flame generator 14 that is mounted in a main passageway 15 of the reformer 12 and generates a pilot flame 16 in part by use of air and/or fuel from the main passageway 15 to initiate a partial oxidation reaction of a fuel-rich air-and-fuel main mixture in the main passageway 15 so as to generate the reformate gas.

A supplier 17 may have an air source 18 and a fuel source 20. In such a case, the air source 18 supplies “air” in the form of, for example, the oxygen component of the exhaust gas of an internal combustion engine (e.g., a diesel engine which outputs exhaust gas with excess oxygen) or atmospheric air which does not undergo combustion with fuel in the engine (e.g., air from an onboard vehicle brake system). As such, the air source 18 may be the internal combustion engine of a vehicle, the vehicle brake system, a turbocharger of a vehicle, an onboard air pump, or other device that provides oxygen alone or in combination with other gases to the reformer 12. It is thus to be understood that the term “air” as used herein means a gas at least a portion of which is oxygen. Exemplarily, such gas may be atmospheric air (i.e., about 21% oxygen, about 78% nitrogen, and trace amounts of other gases), exhaust gas containing oxygen, or pure oxygen.

In any case, such “air,” or main flow, is supplied by the source 18 to a main inlet 21 of the main passageway 15 defined in a conduit 22 of the reformer 12 upstream from the pilot flame generator 14. The main passageway 15 is configured as an exhaust gas passageway (or exhaust gas main passageway) in the case where the source 18 is configured as an engine or other source of emissions. Operation of the fuel source 20 is discussed in more detail below.

A portion of the main flow passes through an annular section 24 of the main passageway 15. A swirler 26 imparts a swirling motion to that portion of the main flow as it enters the annular section 24 to promote mixing with fuel dispensed into the annular section 24.

Downstream from the swirler 26 are a number of fuel dispensers 28 of the supplier 17 that receive fuel from the fuel source 20 via fuel lines 29. Illustratively, there are two such fuel dispensers 28, although the number may be more or less than two. The dispensers 28 are spaced circumferentially about an axis 31 of the main passageway 15 and aimed at an outer surface 30 of a pilot tube 32 of the pilot flame generator 14. In particular, each dispenser 28 is oriented relative to the axis 31 so as to direct fuel radially inwardly and axially downstream (relative to the flow direction of the main flow) against the outer surface 30 which becomes relatively hot due to operation of the pilot flame generator 14. Such heating of the outer surface 30 vaporizes the fuel that impinges against it for mixture with the portion of the main flow in the annular section 24 to provide a fuel-rich air-and-fuel main mixture to be reacted by the pilot flame 16. Exemplarily, the air-fuel ratio of the main mixture is between about 4.5 and about 5.5.

The portion of the main flow that does not enter the section 24 enters the pilot flame generator 14. In particular, it advances through a pilot inlet 34 into a pilot passageway 36 defined in the pilot tube 32. A swirler 38 at the inlet 34 imparts a swirling motion to the flow as it enters the pilot passageway 36 so as to swirl-stabilize the fuel output of a fuel dispenser 40 of the supplier 17 that receives fuel from the fuel source 20 via a fuel line 41 and is surrounded by the swirler 38. The fuel dispensed by the fuel dispenser 40 mixes with the portion of the main flow that enters the pilot passageway 36 to provide therein an air-and-fuel pilot mixture that is less fuel-rich than the main mixture so as to be readily ignitable by an ignition device 42 mounted in the pilot passageway 36. The ignition device 42 ignites the pilot mixture in the pilot passageway 36 so as to generate the pilot flame 16, thereby creating a first reaction zone of the fuel reformer 12. A control device 44 (e.g., swirler, flame holder) may be secured to an end of the pilot tube 32 for management of the flame and/or flow exiting the pilot tube 32.

Such burning of the pilot mixture serves two purposes. First, as alluded to above, it heats the pilot tube 32 and the outer surface 30 thereof for vaporization of the fuel dispensed by the fuel dispenser(s) 28. Second, it provides sufficient thermal energy to at least initiate partial oxidation of the fuel-rich air-and-fuel main mixture. A fuel-reforming catalyst 46 may be positioned downstream from the pilot flame generator 14 to increase the yield of reformate gas. In some cases, the burning of the pilot mixture may provide sufficient thermal energy to also complete partial oxidation of the main mixture. In such cases, the fuel-reforming catalyst 46 may be omitted.

The partial oxidation of the main mixture occurs in the main passageway 15 just downstream from the pilot flame generator 14 in a second reaction zone of the reformer 12. The pilot flame 16 initiates the partial oxidation reaction of the main mixture to generate the reformate gas. The reformate gas exits the main passageway 15 through a main outlet 48 for advancement to the reformate gas user 13 downstream therefrom.

An electronic controller 50 controls operation of the supplier 17 and the ignition device 42 via control lines 52, 54, respectively. Depending on the particular configuration of the supplier 17, the controller 50 may operate various valves and pumps to control flow of air and fuel to the reformer 12. The controller 50 comprises a processor 56 and a memory device 58 electrically coupled to the processor 56 and having instructions stored therein to cause the processor 56 to perform the functions of the controller 50.

Referring to FIG. 2, there is shown a reformer bypass 60 to control flow of exhaust gas, and thus the oxygen content thereof, to the reformer 12. The reformer bypass 60 comprises a bypass passageway 62 in flow-parallel with the main passageway 15. As such, the main and bypass passageways 15, 62 are fluidly coupled to one another at upstream and downstream junctions. A bypass valve 64 (e.g., a butterfly valve) is mounted in the bypass passageway 62 and is under the control of the controller 50 via a control line 66. The bypass valve 64 is able to move (e.g., rotate) in response to signals on the control line 66 from the controller 50 to adjust flow through the bypass passageway 62 and, as a result, flow through the main passageway 15 to assist with control of the air-fuel ratios of the main and pilot mixtures.

Referring to FIG. 3, there is shown an apparatus 110 comprising a fuel reformer 112 that generates reformate gas for use by the reformate gas user 13. The fuel reformer 112 includes several components similar in structure and function to components of the fuel reformer 12. Such similar components are thus identified by the same reference numbers as in FIGS. 1 and 2. The fuel reformer 112 is different primarily in the way that the main and pilot mixtures are provided, as discussed below.

The apparatus 110 has a supplier 117 which is under the control of the controller 50 and provides the air and fuel for operation of the reformer 112. Illustratively, the supplier 117 has the air and fuel sources 18, 20 but is configured in a manner different from the supplier 17 in that it provides in the main passageway 15 the fuel-rich air-and-fuel main mixture upstream, rather than downstream, from the pilot inlet 34 of the pilot flame generator 14. Exemplarily, the air-fuel ratio of the main mixture is between about 4.5 and about 5.5. A portion of that main mixture flows through the annular section 24 while the remainder flows through the pilot inlet 34 into the pilot passageway 36. Since the portion of the main mixture entering the pilot passageway 36 is fuel-rich, there is an air dispenser 140 located in the pilot passageway 36 to dispense air into the pilot passageway 36 to provide a less fuel-rich air-and-fuel pilot mixture therein, such mixture being more readily ignitable than the fuel-rich air-and-fuel main mixture. Exemplarily, the air source 18 of the supplier 117 provides atmospheric air, rather than exhaust gas, to provide the main and pilot mixtures.

The ignition device 42 under the control of the controller 50 ignites the pilot mixture to generate the pilot flame 16 which initiates the partial oxidation reaction of the portion of the main mixture exiting the annular section 24 of the main passageway 15 to generate the reformate gas. The fuel-reforming catalyst 46 may be included to increase the reformate gas yield or omitted if, for example, the pilot flame 16 provides sufficient thermal energy to complete the partial oxidation reaction.

While the concepts of the present disclosure have been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

There are a plurality of advantages of the concepts of the present disclosure arising from the various features of the systems described herein. It will be noted that alternative embodiments of each of the systems of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of a system that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method of operating a fuel reformer, comprising the steps of:

supplying air and fuel to a main passageway so as to provide an air-and-fuel main mixture in the main passageway, the main mixture being fuel-rich,

supplying air and fuel to a pilot passageway located within the main passageway in part by air and/or fuel supplied to the main passageway so as to provide an air-and-fuel pilot mixture in the pilot passageway, the pilot mixture being less fuel-rich than the main mixture,

igniting the pilot mixture so as to generate a pilot flame, and

initiating a partial oxidation reaction of the main mixture with the pilot flame so as to generate reformate gas.

2. The method of claim 1, further comprising heating a pilot tube defining the pilot passageway by use of the pilot flame, wherein:

the step of supplying air and fuel to the main passageway comprises dispensing fuel against an outer surface of the heated pilot tube so as to vaporize the dispensed fuel in the main passageway, and

the initiating step comprises partially oxidizing the vaporized fuel by use of the pilot flame.

3. The method of claim 1, wherein:

the igniting step comprises generating the pilot flame in a pilot tube located in the main passageway and defining the pilot passageway, and

the initiating step comprises partially oxidizing fuel of the main mixture outside the pilot tube.

4. The method of claim 1, wherein:

the step of supplying air and fuel to the main passageway comprises introducing the fuel-rich air-and-fuel main mixture to the main passageway upstream from a pilot inlet of the pilot passageway,

the step of supplying air and fuel to the pilot passageway comprises (i) advancing a fuel-rich portion of the fuel-rich air-and-fuel mixture through the pilot inlet into the pilot passageway, and (ii) introducing air into the pilot passageway for mixture with the fuel-rich portion of the fuel-rich air-and-fuel mixture to provide the pilot mixture.

5. The method of claim 1, wherein:

the step of supplying air and fuel to the main passageway comprises (i) introducing air into the main passageway upstream from a pilot inlet of the pilot passageway, and (ii) introducing fuel into the main passageway downstream from the pilot inlet, and

the step of supplying air and fuel to the pilot passageway comprises (i) advancing a portion of the air introduced into the main passageway through the pilot inlet into the pilot passageway, and (ii) introducing fuel into the pilot passageway for mixture with the portion of the air therein to provide the pilot mixture.

6. The method of claim 1, wherein:

the step of supplying air and fuel to the main passageway comprises (i) introducing exhaust gas into the main passageway upstream from a pilot inlet of the pilot passageway, and (ii) introducing fuel into the main passageway downstream from the pilot inlet, and

the step of supplying air and fuel to the pilot passageway comprises (i) advancing a portion of the exhaust gas from the main passageway through the pilot inlet into the pilot passageway, and (ii) introducing fuel into the pilot passageway for mixture with the portion of the exhaust gas therein to provide the pilot mixture.

7. An apparatus, comprising:

a supplier of air and/or fuel,

a main passageway fluidly coupled to the supplier to receive air and/or fuel therefrom to provide a fuel-rich air-and-fuel main mixture in the main passageway, and

a pilot flame generator mounted in the main passageway, the pilot flame generator defining therein a pilot passageway fluidly coupled to the supplier to receive air and/or fuel therefrom and fluidly coupled to the main passageway to receive air and/or fuel therefrom to provide an air-and-fuel pilot mixture in the pilot passageway, the pilot flame generator comprising an ignition device configured to ignite the pilot mixture to generate a pilot flame that initiates a partial oxidation reaction of the main mixture so as to generate reformate gas.

8. The apparatus of claim 7, further comprising a controller electrically coupled to the supplier and the ignition device, wherein the controller comprises a processor and a memory device electrically coupled to the processor, the memory device having stored therein a plurality of instructions which, when executed by the processor, causes the processor to operate the supplier and the ignition device.

9. The apparatus of claim 7, wherein:

the main passageway is defined in a conduit,

the pilot flame generator comprises a pilot tube that is positioned within the conduit, defines the pilot passageway, and cooperates with the conduit to define at least a portion of the main passageway therebetween, and

the ignition device is mounted in the pilot tube.

10. The apparatus of claim 9, wherein the supplier comprises a fuel dispenser secured to the conduit and aimed at an outer surface of the pilot tube to dispense fuel against the outer surface.

11. The apparatus of claim 9, wherein the conduit and the pilot tube are coaxial.

12. The apparatus of claim 7, wherein the supplier supplies the fuel-rich air-and-fuel mixture to the main passageway upstream from the pilot flame generator.

13. The apparatus of claim 7, wherein the supplier supplies air to the main passageway upstream from an air inlet of the pilot flame generator and supplies fuel to the main passageway downstream from the air inlet and fuel to the pilot passageway.

14. The apparatus of claim 7, wherein:

the main passageway is an exhaust gas passageway, and

the supplier supplies fuel to the exhaust gas passageway and the pilot passageway.

15. The apparatus of claim 7, wherein the supplier comprises a fuel dispenser aimed at an outer surface of the pilot flame generator.

16. The apparatus of claim 7, wherein the apparatus is devoid of a fuel-reforming catalyst.

17. The apparatus of claim 7, further comprising a fuel-reforming catalyst downstream from the pilot flame generator.

18. An apparatus, comprising:

an exhaust gas main passageway,

a main fuel dispenser and a pilot fuel dispenser, and

a pilot flame generator mounted in the main passageway, the pilot flame generator defining therein a pilot passageway open to the main passageway to receive exhaust gas therefrom, the pilot fuel dispenser arranged to introduce fuel into the pilot passageway for mixture with exhaust gas introduced from the main passageway into the pilot passageway to provide an air-and-fuel pilot mixture in the pilot passageway, the pilot flame generator comprising an ignition device arranged to ignite the pilot mixture to generate a pilot flame, the main fuel dispenser arranged to dispense fuel into the main passageway against the outer surface which is heated by the pilot flame for vaporization of such fuel to provide a fuel-rich air-and-fuel main mixture in the main passageway, the pilot flame for initiating a partial oxidation reaction of the main mixture to generate reformate gas.

19. The apparatus of claim 18, wherein:

the main passageway and the pilot passageway are coaxial relative to an axis, and

the main fuel dispenser is oriented relative to the axis to direct fuel axially and radially toward the axis.

20. The apparatus of claim 18, further comprising another main fuel dispenser arranged to dispense fuel into the main passageway against the outer surface.