Electrically stabilized down-fired flame reactor

Abstract

A down-fired flame burner includes a flame charger and one or more field electrodes configured to control flame shape and/or heat transfer to a chemical reactor.

What is claimed is: 
     
         1 . An electrically stabilized down-fired flame reactor, comprising:
 a plurality of catalyst-packed tubes extending vertically in a heating volume;   one or more downward-fired burners configured to project one or more flames downward to heat the plurality of catalyst-packed tubes;   one or more flame charge electrodes respectively associated with each downward-fired burner and configured to cause the one or more flames to carry a majority charge species; and   one or more field electrodes operatively coupled to each tube and configured to electrically interact with the majority charge species in the one or more flames to control heat transfer from the one or more flames to the tubes.   
     
     
         2 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the one or more field electrodes include one or more shield electrodes. 
     
     
         3 . The electrically stabilized down-fired flame reactor of  claim 2 , wherein the one or more shield electrodes include one or more electrodes disposed between each tube and a proximal flame, the one or more shield electrodes being at least transiently held at a voltage having a same polarity as the majority charge in the flame. 
     
     
         4 . The electrically stabilized down-fired flame reactor of  claim 2 , wherein the one or more shield electrodes are configured to reduce direct impingement of the flame on the respective tubes. 
     
     
         5 . The electrically stabilized down-fired flame reactor of  claim 2 , wherein the one or more shield electrodes are configured to reduce or eliminate hot spots on the tubes. 
     
     
         6 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the one or more field electrodes include one or more attraction electrodes. 
     
     
         7 . The electrically stabilized down-fired flame reactor of  claim 6 , wherein the one or more attraction electrodes include one or more electrodes disposed between each tube and a proximal flame, the one or more attraction electrodes being at least transiently held at a voltage having an opposite polarity from the majority charge species in the flame. 
     
     
         8 . The electrically stabilized down-fired flame reactor of  claim 6 , wherein the one or more attraction electrodes are thermally coupled to a respective tube by a thermal coupling. 
     
     
         9 . The electrically stabilized down-fired flame reactor of  claim 8 , wherein each thermal coupling is configured as an electrical insulator or high impedance electrical conductor. 
     
     
         10 . The electrically stabilized down-fired flame reactor of  claim 6 , wherein the one or more attraction electrodes are configured to increase heat transfer to the tubes compared to tubes not including the one or more attraction electrodes. 
     
     
         11 . The electrically stabilized down-fired flame reactor of  claim 6 , wherein the one or more attraction electrodes are configured to draw the flame down toward a bottom end of the tubes. 
     
     
         12 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the one or more flame charge electrodes include a flame charge electrode respectively formed integrally with each burner. 
     
     
         13 . The electrically stabilized down-fired flame reactor of  claim 1 , further comprising one or more power supplies configured to apply one or more electrical potentials to the one or more flame charge electrodes. 
     
     
         14 . The electrically stabilized down-fired flame reactor of  claim 13 , wherein the one or more power supplies are configured to apply a substantially constant voltage to the plurality of flame charge electrodes. 
     
     
         15 . The electrically stabilized down-fired flame reactor of  claim 13 , wherein the one or more power supplies are configured to apply a time-varying voltage to the plurality of flame charge electrodes. 
     
     
         16 . The electrically stabilized down-fired flame reactor of  claim 15 , wherein one or more field electrodes are configured to be driven synchronously with the plurality of flame charge electrodes. 
     
     
         17 . The electrically stabilized down-fired flame reactor of  claim 15 , further comprising an electrode controller configured to drive the one or more power supplies with a waveform corresponding to the time-varying voltage. 
     
     
         18 . The electrically stabilized down-fired flame reactor of  claim 15 , wherein the time-varying voltage includes intervals with positive voltage and intervals with negative voltage. 
     
     
         19 . The electrically stabilized down-fired flame reactor of  claim 1 , further comprising one or more power supplies configured to apply one or more electrical potentials to the one or more field electrodes. 
     
     
         20 . The electrically stabilized down-fired flame reactor of  claim 19 , wherein the one or more power supplies are configured to apply a substantially constant voltage to the one or more field electrodes. 
     
     
         21 . The electrically stabilized down-fired flame reactor of  claim 19 , wherein the one or more power supplies are configured to apply a time-varying voltage to the one or more field electrodes. 
     
     
         22 . The electrically stabilized down-fired flame reactor of  claim 21 , wherein one or more field electrodes are configured to be driven synchronously with the one or more flame charge electrodes. 
     
     
         23 . The electrically stabilized down-fired flame reactor of  claim 21 , further comprising an electrode controller including a waveform generator configured to drive the one or more power supplies with a waveform corresponding to the time-varying voltage. 
     
     
         24 . The electrically stabilized down-fired flame reactor of  claim 21 , wherein the time-varying voltage includes intervals with positive voltage and intervals with negative voltage. 
     
     
         25 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the one or more field electrodes include one or more shield electrodes and one or more attraction electrodes. 
     
     
         26 . The electrically stabilized down-fired flame reactor of  claim 1 , comprising a steam methane reformer. 
     
     
         27 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the plurality of catalyst-packed tubes are arranged in flow-coupled pairs via a tube fitting or bend at lower ends of each flow-coupled pair, each flow-coupled pair being configured to receive reactants through an input end and output reaction products through an output end near a ceiling of the heating volume 
     
     
         28 . The electrically stabilized down-fired flame reactor of  claim 1 , wherein the one or more field electrodes comprise one or more flame attraction electrodes, and
 further comprising:   a power supply operatively coupled to the one or more flame charge electrodes and to the one or more flame attraction electrodes, the power supply being configured to output a flame charge voltage to one or more flame charge electrodes and to output an attraction voltage opposite in polarity from the flame charge voltage to the one or more flame attraction electrodes; and   a current limiting device operatively coupled between the power supply and each flame attraction electrode.   
     
     
         29 . The electrically stabilized down-fired flame reactor of  claim 28 , wherein the current limiting device includes a resistor. 
     
     
         30 . The electrically stabilized down-fired flame reactor of  claim 29 , wherein the resistor has a resistance of about  6  mega-ohms to  8  mega-ohms. 
     
     
         31 . A method for providing process heat, comprising:
 projecting a down-fired flame in a heating volume;   applying a voltage to the flame to produce a majority charge in the flame;   applying an electric field proximate the down-fired flame to control flame shape, heat transfer from the flame, or flame shape and heat transfer from the flame; and   applying heat from the flame to a chemical reactor.   
     
     
         32 . The method for providing process heat of  claim 31 , wherein projecting a down-fired flame in a heating volume includes projecting a plurality of down-fired flames; and
 wherein applying heat from the plurality of flames to a chemical reactor includes heating a plurality of substantially vertical tubes containing catalyst-packing and flowing reactants and one or more products.   
     
     
         33 . The method for providing process heat of  claim 31 , wherein applying a voltage to the flame to produce a majority charge in the flame includes applying an electric potential having a same sign as the majority charge to a charge depletion electrode proximate an upper end of the flame. 
     
     
         34 . The method for providing process heat of  claim 31 , wherein applying a voltage to the flame to produce a majority charge in the flame includes applying the voltage with a flame charge electrode formed integrally with a flame holder. 
     
     
         35 . The method for providing process heat of  claim 31 , wherein applying a voltage to the flame to produce a majority charge in the flame includes modulating the voltage to produce a modulated majority charge in the flame. 
     
     
         36 . The method for providing process heat of  claim 35 , wherein applying a voltage to the flame to produce a majority charge in the flame includes modulating a flame charge electrode through positive and negative potentials to produce a modulated majority charge including a modulated polarity. 
     
     
         37 . The method for providing process heat of  claim 31 , wherein applying a voltage to the flame to produce a majority charge in the flame includes applying a substantially constant voltage to a flame charge electrode to produce a substantially constant concentration of majority charge species having a single polarity. 
     
     
         38 . The method for providing process heat of  claim 31 , wherein applying an electric field proximate the down-fired flame to control one or more of flame shape and heat transfer from the flame includes causing the applied electric field to electrically interact with chemical species or electrons carrying the majority charge in the flame. 
     
     
         39 . The method for providing process heat of  claim 31 , wherein applying an electric field proximate the down-fired flame to control one or more of flame shape and heat transfer from the flame includes shielding a portion of the chemical reactor from the flame with a shield electrode at least transiently carrying an electrical potential having a same polarity as the majority charge. 
     
     
         40 . The method for providing process heat of  claim 31 , wherein applying an electric field proximate the down-fired flame to control one or more of flame shape and heat transfer from the flame includes attracting the flame toward a portion of the chemical reactor by at least transiently applying a voltage having an opposite polarity from the majority charge in the flame to one or more attraction electrodes. 
     
     
         41 . The method for providing process heat of  claim 31 , wherein applying an electric field proximate the down-fired flame to control one or more of flame shape and heat transfer from the flame includes attracting the flame toward a distal location below a location from which the flame is projected by at least transiently applying to one or more attraction electrodes a voltage having an opposite polarity from the majority charge in the flame. 
     
     
         42 . The method for providing process heat of  claim 31 , wherein applying an electric field proximate the down-fired flame to control one or more of flame shape and heat transfer from the flame includes:
 shielding a first portion of the chemical reactor from the flame with a shield electrode at least transiently carrying an electrical potential having a same potential as the majority charge; and   attracting the flame toward a second portion of the chemical reactor or toward a distal location below a location from which the flame is projected by at least transiently applying to one or more attraction electrodes a voltage having an opposite polarity from the majority charge in the flame.   
     
     
         43 . The method for providing process heat of  claim 31 , further comprising:
 operating one or more power supplies to apply a voltage to a flame charge electrode and to one or more field electrodes.   
     
     
         44 . The method for providing process heat of  claim 43 , further comprising:
 operating an electrode controller to cause the one or more power supplies to apply a time-varying voltage to a flame charge electrode to produce a time varying majority charge in the flame; and   operating the electrode controller to apply one or more time varying voltages to one or more field electrodes near the down-fired flame to control the one or more of flame shape and heat transfer from the flame.   
     
     
         45 . The method for providing process heat of  claim 44 , wherein operating the electrode controller includes synchronously driving the flame charge electrode and the one or more field electrodes. 
     
     
         46 . The method for providing process heat of  claim 31 , wherein the chemical reactor includes a steam methane reformer. 
     
     
         47 . A down-fired burner, comprising:
 a fuel nozzle configured to emit a fuel jet in a downward direction;   a flame holder disposed adjacent to the fuel nozzle and configured to anchor a flame supported by the fuel jet;   a power supply configured to output a high magnitude voltage;   a flame charge electrode operatively coupled to receive the high magnitude voltage from the power supply and configured to apply the high magnitude voltage to the flame; and   an attraction electrode below and distal from the fuel nozzle and the flame holder, the attraction electrode being configured to carry an electrical potential selected to electrostatically attract the high magnitude voltage.   
     
     
         48 . The down-fired burner of  claim 47 , wherein the flame holder is formed from a refractory material; and
 wherein the flame charge electrode includes a plurality of flame charge electrodes extending through the flame holder.   
     
     
         49 . The down-fired burner of  claim 47 , further comprising:
 a current limiter operatively coupled between the power supply and the attraction electrode, the current limiter being configured to limit electrical current when the flame comes into electrical continuity with the attraction electrode.   
     
     
         50 . The down-fired burner of  claim 49 , wherein the current limiter includes a resistor.