WO2006099070A1 - Electrode assembly of a plasma fuel reformer - Google Patents

Electrode assembly of a plasma fuel reformer Download PDF

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Publication number
WO2006099070A1
WO2006099070A1 PCT/US2006/008467 US2006008467W WO2006099070A1 WO 2006099070 A1 WO2006099070 A1 WO 2006099070A1 US 2006008467 W US2006008467 W US 2006008467W WO 2006099070 A1 WO2006099070 A1 WO 2006099070A1
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WIPO (PCT)
Prior art keywords
electrode
length
rim
fuel reformer
axial surface
Prior art date
Application number
PCT/US2006/008467
Other languages
French (fr)
Inventor
Stephen Goldschmidt
Navin Khadiya
Samuel N. Crane, Jr
Michael W Greathouse
Michael S Blackwood
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Arvin Technologies, Inc.
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Application filed by Arvin Technologies, Inc. filed Critical Arvin Technologies, Inc.
Publication of WO2006099070A1 publication Critical patent/WO2006099070A1/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C01B3/342—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents with the aid of electrical means, electromagnetic or mechanical vibrations, or particle radiations
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/3478—Geometrical details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0809—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0832—Details relating to the shape of the electrodes essentially toroidal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0869—Feeding or evacuating the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0881—Two or more materials
    • B01J2219/0883—Gas-gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/025—Processes for making hydrogen or synthesis gas containing a partial oxidation step
    • C01B2203/0255—Processes for making hydrogen or synthesis gas containing a partial oxidation step containing a non-catalytic partial oxidation step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C01B2203/066—Integration with other chemical processes with fuel cells
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/08—Methods of heating or cooling
    • C01B2203/0805—Methods of heating the process for making hydrogen or synthesis gas
    • C01B2203/0861—Methods of heating the process for making hydrogen or synthesis gas by plasma

Definitions

  • the present disclosure relates generally to fuel reformers and systems and methods associated therewith.
  • Plasma fuel reformers reform hydrocarbon fuel into a reformate gas such as hydrogen-rich gas.
  • the reformate gas produced by the reformer may be utilized as fuel or fuel additive in the operation of an internal combustion engine.
  • the reformate gas may also be utilized to regenerate or otherwise condition an emission abatement device associated with the internal combustion engine or as a fuel for a fuel cell.
  • a plasma fuel reformer includes an electrode assembly.
  • the electrode assembly includes an upper electrode and a lower electrode spaced apart from the upper electrode to define an electrode gap.
  • the lower electrode includes a rim which is configured to facilitate a reduction in the power level required to operate the fuel reformer.
  • the rim includes an axial surface. Arc discharges generated on the upper electrode terminate on the axial surface.
  • the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 5:1. In another exemplary implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap 40 less than 5:1.
  • the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 3:1. In a more specific implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 1.25:1. For example, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap may be 1.27: 1.
  • the positions of the electrodes may be swapped with the aforedescribed electrode having a rim which is configured to facilitate a reduction in the power level required to operate the fuel reformer being arranged as the upper electrode.
  • FIG. 1 is a perspective view showing a plasma fuel reformer with a plasma generator shown in solid and a reactor shown in phantom;
  • FIG. 2 is a sectional view of the plasma generator of FIG. 1; and FIG. 3 is an enlarged sectional view of the lower electrode.
  • the fuel reformer 10 is embodied as a plasma fuel reformer.
  • a plasma fuel reformer uses plasma (an electrically heated gas) to convert a mixture of air and hydrocarbon fuel into a reformate gas which is rich in, amongst other things, hydrogen gas and carbon monoxide.
  • Systems including plasma fuel reformers are disclosed in U.S. Patent No. 5,425,332 issued to Rabinovich et al.; U.S. Patent No. 5,437,250 issued to Rabinovich et al.; U.S. Patent No. 5,409,784 issued to Bromberg et al.; and U.S. Patent No. 5,887,554 issued to Cohn, et al.
  • Hydrogen-rich gas generated by the fuel reformer 10 may be supplied to an internal combustion engine (not shown) such as a spark-ignited gasoline engine. In such a case, the internal combustion engine combusts the reformate gas as either the sole source of fuel, or alternatively, as a fuel additive to a hydrocarbon fuel.
  • hydrogen-rich gas generated by the fuel reformer 10 may be supplied to a fuel cell (not shown) such as an alkaline fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a proton exchange membrane fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), or any other type of fuel cell.
  • AFC alkaline fuel cell
  • PAFC phosphoric acid fuel cell
  • PEMFC proton exchange membrane fuel cell
  • SOFC solid oxide fuel cell
  • MCFC molten carbonate fuel cell
  • the fuel cell utilizes the hydrogen-rich gas in the production of electrical energy.
  • the hydrogen-rich gas from the fuel reformer 10 may also be supplied to an emission abatement device such as a NOx trap or a soot filter to facilitate regeneration thereof.
  • the fuel reformer 10 includes a plasma generator 12 and a reactor 14, as shown in FIG. 1.
  • the plasma generator 12 generates a plasma arc using electrical power from an electrical power supply 16.
  • a mixture of air from an air supply 18 and hydrocarbon fuel from a fuel supply 20 passes through the plasma arc and into the reactor 14 to reform the hydrocarbon fuel into a reformate gas.
  • Electrical power is introduced into the plasma generator 12 by use of a power connector (not shown) which is advanced through an electrical power inlet 22.
  • Air is introduced into the plasma generator 12 through a pair of upper air inlets 24, 25 and a lower air inlet 26.
  • Fuel is introduced into the plasma generator 12 through a fuel injection assembly 28.
  • the plasma arc is generated by an electrode assembly 30.
  • the electrode assembly 30 includes an annular upper electrode 34 and an annular lower electrode 36, as shown in FIG. 2.
  • the upper electrode 34 is electrically coupled to the electrical power supply 16.
  • the lower electrode 36 is electrically coupled to ground 38.
  • the upper electrode 34 and lower electrode 36 are spaced apart to define an electrode gap 40 therebetween. When energized by the electrical power supply 16, the upper and lower electrodes 34, 36 cooperate to generate the plasma arc across the electrode gap 40.
  • the lower electrode 36 has an arc contact rim 42.
  • the arc contact rim 42 includes an outer annular face 44 and an oppositely facing inner annular face 46.
  • the two faces 44, 46 are separated by an axial surface 48.
  • Arc discharges generated on the upper electrode 34 by the power supply 16 terminate on one or both of the outer annular face 44 or the axial surface 58 of the lower electrode 36.
  • the length of the axial surface 48 in essence, defines the thickness of the rim 42.
  • the length of the axial surface 48 of the lower electrode 36 is designated with reference character "L E " in FIGS. 2 and 3.
  • the lower electrode 36 also has a cylindrically-shaped wall 50 extending downwardly from the rim 42.
  • the wall 50 defines an annular chamber 52. Reformed, or partially reformed, gas exiting the plasma arc is advanced through the opening 54 defined in the rim 42 and into the chamber 52. Such gases exit the chamber 52 and are then advanced into the reactor 14.
  • the length (L E ) of the axial surface 48 of the rim 42 is reduced relative to heretofore designed electrode assemblies. Indeed, by reducing the ratio of the length (L E ) of the axial surface 48 relative to the length of the electrode gap 40 (designated as "L G " in FIG. 2), higher ion densities may be achieved thereby reducing the power requirements associated with operation of the fuel reformer 10.
  • the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 5:1 (i.e., L E :LQ ⁇ 5:1). In another exemplary implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is less than 5:1 (i.e., L E :LQ ⁇ 5:1). For example, in another exemplary implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 3:1 (i.e., L E :L G ⁇ 3:1).
  • the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 1.25:1 (i.e., L E :L G ⁇ 1.25:1).
  • Such an arrangement reduces the electrical power required to ignite fuel in the plasma generator 12 to a level that is potentially below 250 Watts.
  • Prior designs often require power levels in the range of 550 Watts to ignite air/fuel mixtures, particularly during cold ignition events (e.g., -2O 0 C). Power supply reliability and durability are enhanced at lower power levels.
  • the embodiments described herein allow for lower spark ignition power levels by reducing the axial surface area of the lower electrode relative to prior designs. Such a reduction of the axial surface area of the lower electrode generates an increase in the ion density of electrical plasma. This increase in ion density in the electrical plasma allows lower power levels to generate good cold start ignition results at desired air/fuel mixtures.
  • the electrode designs described herein also allow for more mixing of the gases exiting the plasma arc before they are introduced into the reactor 14. Indeed, the rim 42 functions like a baffle by introducing vorticity in the axial flow. This causes increased turbulence, and therefore better mixing of the gases. Since this occurs downstream of the plasma arc, combustion reactions are accelerated thereby producing greater hydrogen quantities while lowering soot formation.
  • use of the lower electrode 36 described herein reduces heat losses from the region of the plasma arc, especially during start-up when the electrode region has the highest temperature. In essence, the reduction in the cross sectional area of the lower electrode body causes lower conductivity in the axial direction.

Abstract

A plasma fuel reformer includes an electrode assembly having an upper electrode and a lower electrode spaced apart from the upper electrode to define an electrode gap. The lower electrode includes a rim which is configured to facilitate a reduction in the power level required to operate the fuel reformer.

Description

ELECTRODEASSEMBLY OFAPLASMAFUELREFORMER
This application claims priority under 35 U.S. C. § 119(e) to U.S. Provisional Patent Application Serial No. 60/660,360, entitled "Electrode Assembly of a Fuel Reformer and Associated Method" filed on March 10, 2005 by Stephen P. Goldschmidt et al., the entirety of which is hereby incorporated by reference.
FIELD OF THE DISCLOSURE
The present disclosure relates generally to fuel reformers and systems and methods associated therewith.
BACKGROUND
Plasma fuel reformers reform hydrocarbon fuel into a reformate gas such as hydrogen-rich gas. In the case of a plasma fuel reformer onboard a vehicle or stationary power generator, the reformate gas produced by the reformer may be utilized as fuel or fuel additive in the operation of an internal combustion engine. The reformate gas may also be utilized to regenerate or otherwise condition an emission abatement device associated with the internal combustion engine or as a fuel for a fuel cell.
SUMMARY
According to an aspect of the present disclosure, a plasma fuel reformer is described. The plasma fuel reformer includes an electrode assembly. The electrode assembly includes an upper electrode and a lower electrode spaced apart from the upper electrode to define an electrode gap. The lower electrode includes a rim which is configured to facilitate a reduction in the power level required to operate the fuel reformer. In certain embodiments, the rim includes an axial surface. Arc discharges generated on the upper electrode terminate on the axial surface. In one exemplary implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 5:1. In another exemplary implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap 40 less than 5:1. In another exemplary implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 3:1. In a more specific implementation, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 1.25:1. For example, the ratio of the length of the axial surface of the rim relative to the length of the electrode gap may be 1.27: 1.
The positions of the electrodes may be swapped with the aforedescribed electrode having a rim which is configured to facilitate a reduction in the power level required to operate the fuel reformer being arranged as the upper electrode.
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 perspective view showing a plasma fuel reformer with a plasma generator shown in solid and a reactor shown in phantom;
FIG. 2 is a sectional view of the plasma generator of FIG. 1; and FIG. 3 is an enlarged sectional view of the lower electrode.
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.
Referring now to FIG. 1, there is shown a fuel reformer 10. The fuel reformer 10 is embodied as a plasma fuel reformer. A plasma fuel reformer uses plasma (an electrically heated gas) to convert a mixture of air and hydrocarbon fuel into a reformate gas which is rich in, amongst other things, hydrogen gas and carbon monoxide. Systems including plasma fuel reformers are disclosed in U.S. Patent No. 5,425,332 issued to Rabinovich et al.; U.S. Patent No. 5,437,250 issued to Rabinovich et al.; U.S. Patent No. 5,409,784 issued to Bromberg et al.; and U.S. Patent No. 5,887,554 issued to Cohn, et al. Additional examples of systems including plasma fuel reformers are disclosed in: (1) copending U.S. Patent Application No. 10/158,615 which is entitled "Low Current Plasmatron Fuel Converter Having Enlarged Volume Discharges," which was filed on May 30, 2002 by A. Rabinovich, N. Alexeev, L. Bromberg, D. Cohn, and A. Samokhin, (2) copending U.S. Patent Application No. 10/411,917 which is entitled "Plasmatron Fuel Converter Having Decoupled Air Flow Control," which was filed on April 11, 2003 by A. Rabinovich, N. Alexeev, L. Bromberg, D. Cohn, and A. Samokhin, and is hereby incorporated by reference herein, (3) copending U.S. Patent Application No. 10/452,623 which is entitled "Fuel Reformer With Cap and Associated Method," which was filed on June 2, 2003 by Michael W. Greathouse and Jon J. Huckaby, (4) copending U.S. Patent Application No. 10/843,776 which is entitled "Plasma Fuel Reformer With One-Piece Body," which was filed on May 12, 2004 by Michael W. Greathouse and Jason
Zhang, and (5) copending U.S. Patent Application No. 60/660,362 which is entitled
"Plasma Fuel Reformer," which was filed March 10, 2005 by Michael W. Greathouse,
Stephen Goldschmidt, Navin Khadiya, Samuel Crane, Robert Iverson, Kendall Duffield, Michael Blackwood, William Taylor, III, Rudolf Smaling, Michael Smith,
Jon Huckaby, Christopher Huffmeyer, and Granville Hayworth, II. Each of the above-identified patents and patent applications are hereby incorporated by reference.
Hydrogen-rich gas generated by the fuel reformer 10 may be supplied to an internal combustion engine (not shown) such as a spark-ignited gasoline engine. In such a case, the internal combustion engine combusts the reformate gas as either the sole source of fuel, or alternatively, as a fuel additive to a hydrocarbon fuel. Alternatively, hydrogen-rich gas generated by the fuel reformer 10 may be supplied to a fuel cell (not shown) such as an alkaline fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a proton exchange membrane fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), or any other type of fuel cell. In such a case, the fuel cell utilizes the hydrogen-rich gas in the production of electrical energy. The hydrogen-rich gas from the fuel reformer 10 may also be supplied to an emission abatement device such as a NOx trap or a soot filter to facilitate regeneration thereof. The fuel reformer 10 includes a plasma generator 12 and a reactor 14, as shown in FIG. 1. The plasma generator 12 generates a plasma arc using electrical power from an electrical power supply 16. A mixture of air from an air supply 18 and hydrocarbon fuel from a fuel supply 20 passes through the plasma arc and into the reactor 14 to reform the hydrocarbon fuel into a reformate gas. Electrical power is introduced into the plasma generator 12 by use of a power connector (not shown) which is advanced through an electrical power inlet 22. Air is introduced into the plasma generator 12 through a pair of upper air inlets 24, 25 and a lower air inlet 26. Fuel is introduced into the plasma generator 12 through a fuel injection assembly 28.
The plasma arc is generated by an electrode assembly 30. The electrode assembly 30 includes an annular upper electrode 34 and an annular lower electrode 36, as shown in FIG. 2. The upper electrode 34 is electrically coupled to the electrical power supply 16. The lower electrode 36 is electrically coupled to ground 38. The upper electrode 34 and lower electrode 36 are spaced apart to define an electrode gap 40 therebetween. When energized by the electrical power supply 16, the upper and lower electrodes 34, 36 cooperate to generate the plasma arc across the electrode gap 40.
As shown in FIGS. 2 and 3, the lower electrode 36 has an arc contact rim 42. In the exemplary embodiment described herein, the arc contact rim 42 includes an outer annular face 44 and an oppositely facing inner annular face 46. The two faces 44, 46 are separated by an axial surface 48. Arc discharges generated on the upper electrode 34 by the power supply 16 terminate on one or both of the outer annular face 44 or the axial surface 58 of the lower electrode 36. The length of the axial surface 48, in essence, defines the thickness of the rim 42. The length of the axial surface 48 of the lower electrode 36 is designated with reference character "LE" in FIGS. 2 and 3. The lower electrode 36 also has a cylindrically-shaped wall 50 extending downwardly from the rim 42. The wall 50 defines an annular chamber 52. Reformed, or partially reformed, gas exiting the plasma arc is advanced through the opening 54 defined in the rim 42 and into the chamber 52. Such gases exit the chamber 52 and are then advanced into the reactor 14. The length (LE) of the axial surface 48 of the rim 42 is reduced relative to heretofore designed electrode assemblies. Indeed, by reducing the ratio of the length (LE) of the axial surface 48 relative to the length of the electrode gap 40 (designated as "LG" in FIG. 2), higher ion densities may be achieved thereby reducing the power requirements associated with operation of the fuel reformer 10. For example, in one exemplary implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 5:1 (i.e., LE:LQ ~ 5:1). In another exemplary implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is less than 5:1 (i.e., LE:LQ < 5:1). For example, in another exemplary implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 3:1 (i.e., LE:LG ~ 3:1). In a more specific implementation, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 is about 1.25:1 (i.e., LE:LG ~ 1.25:1). For example, the ratio of the length of the axial surface 48 relative to the length of the electrode gap 40 maybe 1.27:1 (i.e., LE:LG = 1.27:1).
Such an arrangement reduces the electrical power required to ignite fuel in the plasma generator 12 to a level that is potentially below 250 Watts. Prior designs often require power levels in the range of 550 Watts to ignite air/fuel mixtures, particularly during cold ignition events (e.g., -2O0C). Power supply reliability and durability are enhanced at lower power levels.
In short, the embodiments described herein allow for lower spark ignition power levels by reducing the axial surface area of the lower electrode relative to prior designs. Such a reduction of the axial surface area of the lower electrode generates an increase in the ion density of electrical plasma. This increase in ion density in the electrical plasma allows lower power levels to generate good cold start ignition results at desired air/fuel mixtures. The electrode designs described herein also allow for more mixing of the gases exiting the plasma arc before they are introduced into the reactor 14. Indeed, the rim 42 functions like a baffle by introducing vorticity in the axial flow. This causes increased turbulence, and therefore better mixing of the gases. Since this occurs downstream of the plasma arc, combustion reactions are accelerated thereby producing greater hydrogen quantities while lowering soot formation. Moreover, use of the lower electrode 36 described herein reduces heat losses from the region of the plasma arc, especially during start-up when the electrode region has the highest temperature. In essence, the reduction in the cross sectional area of the lower electrode body causes lower conductivity in the axial direction.
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an 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 present disclosure arising from the various features of the apparatus, method, and system described herein. It will be noted that alternative embodiments 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 an apparatus, method, and system that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention.

Claims

1. A plasma fuel reformer comprising: an electrical power supply, a first electrode, and a second electrode spaced apart from the first electrode to define an electrode gap, the second electrode comprising a rim having an outer surface which faces the first electrode and an axial surface extending away for the outer surface, wherein (i) a number of arc discharges generated by the application of current and voltage to the first electrode by the power supply terminate on the axial surface of the rim, and (ii) the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is less than or equal to 5:1.
2. The plasma fuel reformer of claim 1, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 5:1.
3. The plasma fuel reformer of claim 1, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 3:1.
4. The plasma fuel reformer of claim 1, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is less than
3:1.
5. The plasma fuel reformer of claim 1, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 1.25:1.
6. The plasma fuel reformer of claim 1, wherein: the second electrode further comprises a cylindrically-shaped wall extending downwardly from the rim, the cylindrically-shaped wall defines a chamber, and the axial surface of the of the rim defines an opening which fluidly couples the electrode gap with the chamber.
7. A plasma fuel reformer comprising: a first electrode, and a second electrode spaced apart from the first electrode to define an electrode gap, the second electrode comprising (i) a rim having an outer surface which faces the first electrode and an axial surface which defines an opening, and (ii) a wall extending downwardly from the rim to define a chamber, wherein (i) the opening fluidly couples the electrode gap with the chamber, and (ii) the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is less than or equal to 5:1.
8. The plasma fuel reformer of claim 7, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 5:1.
9. The plasma fuel reformer of claim 7, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 3:1.
10. The plasma fuel reformer of claim 7, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is less than 3:1.
11. The plasma fuel reformer of claim 7, wherein the ratio of the length of the axial surface of the rim relative to the length of the electrode gap is about 1.25:1.
12. The plasma fuel reformer of claim 7, further comprising an electrical power supply electrically coupled to the first electrode.
13. A ground electrode of a plasma fuel reformer comprising (i) a rim having an axial surface on which arc discharges terminate during operation of the plasma fuel reformer, the axial surface defining an opening having a first inner diameter, and (ii) a annular wall extending downwardly from the rim to define an annular chamber having a second inner diameter which is greater than the first inner diameter.
14. The ground electrode of claim 13, wherein: the rim has a first outer diameter, and a portion of the annular wall defines a second outer diameter which is equal to the first outer diameter.
15. The ground electrode of claim 13, wherein the rim and the annular wall are integrally formed with one another.
PCT/US2006/008467 2005-03-10 2006-03-10 Electrode assembly of a plasma fuel reformer WO2006099070A1 (en)

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Cited By (2)

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CN101209815B (en) * 2006-12-29 2011-08-10 财团法人工业技术研究院 Plasma body recombination device and internal combustion engine system with the same
WO2020027702A3 (en) * 2018-07-31 2020-03-12 Plazarium Apparatus and method for plasma-chemical hydrocracking, and plant with such apparatus

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US4493297A (en) * 1982-09-27 1985-01-15 Geo-Centers, Inc. Plasma jet ignition device
US6322757B1 (en) * 1999-08-23 2001-11-27 Massachusetts Institute Of Technology Low power compact plasma fuel converter

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Publication number Priority date Publication date Assignee Title
US4493297A (en) * 1982-09-27 1985-01-15 Geo-Centers, Inc. Plasma jet ignition device
US6322757B1 (en) * 1999-08-23 2001-11-27 Massachusetts Institute Of Technology Low power compact plasma fuel converter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101209815B (en) * 2006-12-29 2011-08-10 财团法人工业技术研究院 Plasma body recombination device and internal combustion engine system with the same
WO2020027702A3 (en) * 2018-07-31 2020-03-12 Plazarium Apparatus and method for plasma-chemical hydrocracking, and plant with such apparatus

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