Abstract:
A system for electrically controlling a combustion reaction includes a charging mechanism with a surface of a charging material with a work function that is sufficiently different from a work function of a charge carrier material to be capable of undergoing contact electrostatic charging. The charge carrier material is contacted with the charging material to impart an electrostatic charge to the charge carrier material, which is then fed to the combustion reaction to introduce a charge corresponding to the electrostatic charge. An aspect of the combustion reaction is controlled by application, to the combustion reaction, of electrical energy, characteristics of which are selected to interact in a predictable way with the combustion reaction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority benefit from U.S. Provisional Patent Application No. 61/736,538, entitled “ELECTRICALLY CONTROLLED COMBUSTION SYSTEM WITH CONTACT ELECTROSTATIC CHARGE GENERATION”, filed Dec. 12, 2012; which, to the extent not inconsistent with the disclosure herein, is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    In electrodynamic combustion control systems (ECC), electrical energy is employed to control various aspects of a combustion reaction. Typically, the electrical energy is applied by electrodes in contact with, or in close proximity to the combustion reaction. For example, one known method is to position a first electrode near or in contact with the combustion reaction and employ a burner nozzle as a second electrode. A voltage is then applied across the combustion reaction between the two electrodes, producing an electrical field extending through the combustion reaction, between the electrodes. As fuel (and/or oxidizer) are emitted via the burner nozzle, an electrical charge is imparted to the fuel. This produces a charge to the combustion reaction whose polarity is opposite that of the first electrode. The position of the first electrode, the polarity and value of the applied voltage, and many other related factors determine the effect of the electrical energy on the combustion reaction. 
         [0003]    The triboelectric effect is a type of contact electrification in which certain materials become electrically charged after they come into contact with another different material. When the two materials are moved across one another, electrons transfer from the surface of one of the materials to the other. Most people are familiar with the experience of feeling a small electric shock upon touching a metal surface after walking across a wool carpet, or having a balloon stick to a piece of clothing after rubbing them together. These are examples of triboelectric charging. 
       SUMMARY 
       [0004]    In an embodiment, an electrodynamic combustion control (ECC) system is provided for electrical control of a combustion reaction. The system includes a contact electrostatic charging material selected to impart an electrostatic charge to a charge carrier material during contact. The system includes a charge carrier feeder configured to cause the charge carrier material to come into contact with the contact electrostatic charging material and impart the electrostatic charge to the charge carrier material. The charge carrier feeder is configured to then feed the charge carrier material to a combustion reaction to cause the combustion reaction to acquire a combustion reaction charge from the electrostatic charge imparted to the charge carrier material. 
         [0005]    According to an embodiment, the charge carrier material is a fuel that is electrostatically charged prior to being ejected from a burner nozzle. According to other embodiments, the charge carrier material can be another material entrained in a flow of fuel, or can be introduced to the combustion reaction via a flow of oxidizer, recirculated flue gas, etc. 
         [0006]    The system also includes an electrodynamic system configured to apply an electric field to the combustion reaction. The electric field is selected to interact with the combustion reaction charge to control a selected aspect or characteristic of the combustion reaction. 
         [0007]    In an embodiment, a method is provided for electrical control of a combustion reaction. The method includes applying an electrostatic charge to a flow of charge carrier material, applying a combustion reaction charge to the combustion reaction by introducing the flow of charge carrier material to the combustion reaction, and controlling an aspect of the combustion reaction by applying, to the combustion reaction, electrical energy selected to interact with the applied combustion reaction charge. 
         [0008]    According to various embodiments, the method can include selecting a contact electrostatic charging material and a charge carrier material capable of undergoing contact electrostatic charging, and contacting the charge carrier material and the contact electrostatic charging material in order to apply the electrostatic charge to the flow of charge carrier material. 
         [0009]    The method further includes applying electrical energy to the combustion reaction, the electrical energy being selected to interact with the combustion reaction charge to cause a measurable effect on the combustion reaction. 
         [0010]    According to an embodiment, the method includes imparting a positive-polarity electrostatic charge to the charge carrier material. According to another embodiment, the method includes imparting a negative-polarity electrostatic charge to the charge carrier material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagram of a system for electrical control of a combustion reaction, according to an embodiment. 
           [0012]      FIG. 2  is a diagram of a system for electrical control of a combustion reaction, including details of an electrodynamic system, according to an embodiment. 
           [0013]      FIG. 3A  is a diagram of a charge carrier feeder, according to an embodiment. 
           [0014]      FIG. 3B  is a diagram of a charge carrier feeder, according to an embodiment. 
           [0015]      FIG. 4  is a diagram of a system for electrical control of a combustion reaction, including a charge carrier collector, according to an embodiment. 
           [0016]      FIG. 5  is a diagram of a charge carrier collector, according to an embodiment. 
           [0017]      FIG. 6  is a diagram of a system for electrical control of a combustion reaction, including details of an electrodynamic system, according to an embodiment. 
           [0018]      FIGS. 7A-7E  are flow diagrams showing various examples of methods for electrical control of a combustion reaction, according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments can be used and/or other changes can be made without departing from the spirit or scope of the disclosure. 
         [0020]      FIG. 1  is a diagram of a system  100  for electrical control of a combustion reaction, according to an embodiment. The system  100  includes a burner  118  configured to support a combustion reaction  102 . 
         [0021]    According to various embodiments, the system  100  for electrical control of a combustion reaction  102  includes a charging mechanism  103  configured to impart an electrostatic charge to a flow  107  of charge carrier material  108 , and to introduce the flow of charge carrier material to the combustion reaction. The charging mechanism  103  includes a contact electrostatic charging material  104  selected to impart an electrostatic charge  106  to charge carrier material  108 , and a charge carrier feeder  110 , configured to cause the charge carrier material  108  to come into contact with the contact electrostatic charging material  104 . Contact with the electrostatic charging material  104  imparts the electrostatic charge  106  to the charge carrier material  108 . The charge carrier material  108  is fed to a combustion reaction  102  to cause the combustion reaction  102  to acquire a combustion reaction charge  112 . In the embodiment of  FIG. 1 , the contact electrostatic charging material  104  forms a portion of the burner  118 . As fuel passes through the burner  118 , a portion of the charge carrier material  108  contacts interior surfaces of the burner  118  on which the electrostatic charging material  104  is positioned. As explained in more detail below, contact between the charge carrier material  108  and the contact electrostatic charging material  104  imparts an electrostatic charge to the charge carrier material  108 . As the contact electrostatic charging material  104  is carried with the fuel to the combustion reaction  102 , the combustion reaction  102  acquires the charge, producing a combustion reaction charge  112 . 
         [0022]    According to various embodiments, an electrodynamic system  114  is configured to apply electrical energy to the combustion reaction  102 . The electrical energy is selected to interact with the combustion reaction charge  112  to cause a measurable effect on the combustion reaction  102 . For example, by interacting with the combustion reaction charge  112 , as well as any other electrical potentials that may be applied to the combustion reaction  102 , an electric field  116  may be formed between elements of the electrodynamic system  114  and the combustion reaction  102 . The interaction of the combustion reaction  102  and the electrodynamic system  114  can be used to control various aspects of the combustion reaction such as, for example, shape, location, luminosity, reaction rate, stability, etc. Hereafter, where an electric field  116  is referred to, this can be construed as including electrical energy applied to the combustion reaction  102  by elements such as those of the electrodynamic system  114 , as well as any resulting potential difference, electric field, etc. 
         [0023]      FIG. 2  is a diagram of a system  200  for electrical control of a combustion reaction, including details of the electrodynamic system  114 , according to an embodiment. 
         [0024]    According to various embodiments, the electrodynamic system  114  includes an electrode  202  configured to apply the electric field  116  to the combustion reaction  102 . Although not shown or described in detail, according to other embodiments, the system  200  can include a plurality of electrodes  202 . For example, U.S. patent application Ser. No. 14/092,836, entitled PRECOMBUSTION IONIZATION, and filed Nov. 27, 2013, describes an electrodynamic combustion control system that employs a plurality of electrodes. The above-referenced application is incorporated herein in its entirety. 
         [0025]    A voltage source  204  is operatively coupled to the electrode  202  and is configured to drive a voltage on the electrode  202  to provide the electric field  116  to the combustion reaction  102 . A controller  206  is operatively coupled to the voltage source  204 . The controller  206  is configured to control the voltage source  204  to drive the electrode  202  to produce the electric field  116 . The voltage source  204  can include a high voltage power supply. 
         [0026]    According to various embodiments, the electrodynamic system  114  is configured to apply to the combustion reaction  102  a charge that is additive to or subtractive from the electrostatic charge  106 . Additionally or alternatively, the electrodynamic system  114  can be configured to apply a voltage to the combustion reaction  102 . According to an embodiment, the electrodynamic system  114  is configured to apply a voltage having the same polarity as the combustion reaction charge  112 . Alternatively, the electrodynamic system  114  can be configured to apply the voltage at a polarity opposite that of the combustion reaction charge  112 , thereby forming the electric field  116 . 
         [0027]    According to various embodiments, the charge carrier material  108  includes a solid. Additionally or alternatively, the charge carrier material  108  includes a particulate. Additionally or alternatively, the charge carrier material  108  includes a dielectric liquid. 
         [0028]    For example, the charge carrier material  108  can include liquid dielectrics such as hydrocarbon fuels that also exhibit contact electrostatic charging. Dielectric liquid hydrocarbon fuels may contain ionic or ionizable species that adsorb on the contact electrostatic charging material  104 . Upon flowing with the hydrocarbon fuel/charge carrier material, the species may charge-separate. Some charges of one polarity may remain associated with the contact electrostatic charging material  104  and some charges of the opposite polarity may flow with the hydrocarbon fuel/charge carrier material. 
         [0029]    Typically, a polarity tends to associate with the contact electrostatic charging material  104  according to a corresponding work function (see the explanation of work function, below). For example, materials with relatively high work functions tend to hold on to negative charges, while positive charges tend to separate and flow with the hydrocarbon fuel/charge carrier material. For example, liquid hydrocarbon fuels in contact with relatively high work function surfaces, e.g., work functions higher than coal, tend to acquire a positive charge. 
         [0030]    According to various embodiments, the charge carrier material  108  includes a fuel that is substantially consumed by the combustion reaction  102 . For example, the fuel can include coal, a dielectric liquid hydrocarbon, or a dielectric liquid having a conductivity of less than about 10 nanoSiemens per meter, etc. 
         [0031]    According to other embodiments, the charge carrier material  108  includes particulates that are substantially nonreactive in the combustion reaction  102 , such as, e.g., quartz or mica, and which can be recovered from the combustion reaction or a flue gas of the combustion reaction. 
         [0032]    The contact electrostatic charging material  104  can include any appropriate material, such as, e.g., a metal, a mineral, a polymer, a glass, a ceramic, etc. 
         [0033]    According to an embodiment, one or more articles operatively coupled to or forming a portion of the charge carrier feeder  110  include portions formed from the contact electrostatic charging material  104 . 
         [0034]      FIGS. 3A and 3B  are diagrams of a charge carrier feeder, according to various embodiments. 
         [0035]    According to an embodiment, the charge carrier feeder  110  is configured to cause the charge carrier material  108  to contact the contact electrostatic charging material  104 , such as by impacting or rubbing, to produce the electrostatic charge  106 . For example, the charge carrier feeder  110  can be provided with internal vanes or convolutions that produce turbulence in a fluid flow and promote increased contact with the charge carrier material  108 . Any or all of the interior surfaces of the charge carrier feeder  110  can be formed or covered with the contact electrostatic charging material  104 , so that contacts with the charge carrier material  108  produces the electrostatic charge  106 . The configuration of the charge carrier feeder  110  is a design choice, and will depend, in part, on the type of charge carrier material it is intended to convey. For example, according to various embodiments, the charge carrier feeder  110  can include a pneumatic feeder, a hydraulic feeder, a belt conveyor, a screw conveyor, a moving grate feeder, a rotary feeder, a paddle feeder, a rotating conduit feeder, a turbocharger, a pump, etc. 
         [0036]    According to various embodiments, a portion  302  of the charge carrier feeder  110  can include a conduit, a chute, a conveyor belt, a conveyor screw, a manifold, a venturi, a filter, a separator, a coalescer, a brush, a piston, a valve, a nozzle, a baffle, a propeller, an impeller, a turbine, a paddle, a fan blade, a propeller housing, an impeller housing, a turbine housing, a fan housing, a mechanical vibrator, a fluidized bed particulate, a fluidized bed chamber wall, a grate, a reservoir, a burner, a fuel nozzle, a fuel source, etc. 
         [0037]    According to an embodiment, the portion  302  of the charge carrier feeder is formed from the contact electrostatic charging material  104 , such that the contact electrostatic charging material  104  is part of the charge carrier feeder  110 . According to an embodiment, the charge carrier feeder  110  is configured to thermally insulate the contact electrostatic charging material  104  from the combustion reaction  102 . According to an embodiment, the contact electrostatic charging material  104  includes a dielectric polymer. 
         [0038]    According to various embodiments, a charge carrier feeder controller  304  is provided, configured to control the charge carrier feeder  110  to increase, decrease, and/or maintain a feeding rate of the charge carrier material to the combustion reaction  102 . According to an embodiment, the charge carrier feeder controller  304  is configured to control a contact electrostatic charging rate between the contact electrostatic charging material  104  and the charge carrier material. 
         [0039]    According to various embodiments, the charge carrier feeder  110  is configured to employ a dielectric liquid as the charge carrier material, the liquid dielectric characterized by an electrostatic charge relaxation time. The charge carrier feeder controller  304  is configured to control a feeding rate of the charge carrier material to the combustion reaction  102  such that a travel time of the charge carrier material between the contact electrostatic charging material  104  and the combustion reaction  102  is less than the electrostatic relaxation time. 
         [0040]    According to an embodiment, the charge carrier feeder  110  includes a contact electrostatic generator  306 , configured to actively promote contact between the contact electrostatic charging material  104  and the charge carrier material  108 . For example, an electrostatic generator can include elements that incorporate surfaces formed from a contact electrostatic charging material, and that spin or rotate through a flow of charge carrier material. The surfaces can be substantially planar, arcuate, ridged, etc., or can be in the form a blade, a propeller, an impeller, etc. Other examples of electrostatic generators include devices configured to generate a static charge by electrical or or electromagnetic means, either formed on the charge carrier material as it passes, or which is first generated, then transferred to the charge carrier material. 
         [0041]    The contact electrostatic generator  306  can include, for example, a cyclonic tribocharger, a static tribocharger, a free-fall tribocharger, a rotating conduit, a rotating blade tribocharger, a turbo tribocharger, a loop tribocharger, a belt tribocharger, a van de Graaf generator, a vibration tribocharger, a fluidized bed tribocharger, etc. 
         [0042]    According to various embodiments, the contact electrostatic generator  306  includes the contact electrostatic charging material  104 . 
         [0043]    According to an embodiment, a contact electrostatic generator controller  308  is configured to control the contact electrostatic generator  306  and the charging rate between the contact electrostatic charging material  104  and the charge carrier material. For example, the contact electrostatic generator controller  308  can be configured to control the contact electrostatic generator  306  to increase, decrease, and/or maintain a contact electrostatic charging rate between the contact electrostatic charging material  104  and the charge carrier material  108 . 
         [0044]      FIG. 4  is a diagram of a system for electrical control of a combustion reaction, including a charge carrier collector, according to an embodiment. 
         [0045]      FIG. 5  is a diagram of a charge carrier collector, according to an embodiment. 
         [0046]    According to various embodiments, a charge carrier collector  402  is configured to recover a portion of the charge carrier material from the combustion reaction  102  or a flue gas of the combustion reaction  102 . The charge carrier collector  402  is configured to recycle the recovered charge carrier material to the combustion reaction  102  and/or the charge carrier material feeder. The charge carrier collector  402  can include an electrostatic precipitator, a baghouse, a settling chamber, a conduit, a baffle, a cyclonic particulate separator, etc. 
         [0047]    According to various embodiments, the charge carrier collector  402  includes one or more recovery electrodes, a voltage source  406  operatively coupled to the one or more recovery electrodes  404 , and a controller  408  operatively coupled to the voltage source  406 . The controller  408  is configured to apply an electric field  116  via the one or more recovery electrodes  404  to recover some or all of the charge carrier material from the combustion reaction  102  or from a flue gas of the combustion reaction  102 . The controller  408  is configured to apply the electric field  116  via the one or more recovery electrodes  404  to direct the recovered charge carrier material to the combustion reaction  102  and/or the charge carrier material feeder. 
         [0048]    According to various embodiments, a burner  118  is configured to support the combustion reaction  102 . The burner  118  is operatively coupled to the charge carrier feeder  110  to direct the charge carrier material from the charge carrier feeder  110  to the combustion reaction  102 . 
         [0049]    According to an embodiment, the contact electrostatic charging material  104  is included in the burner  118 . The charge carrier feeder  110  is configured to contact the charge carrier material to the contact electrostatic charging material  104  in the burner  118  to impart the electrostatic charge  106  to the charge carrier material. The burner  118  is further configured to electrically insulate the electrostatic charge  106  on the charge carrier material from ground or other voltages. 
         [0050]    According to various embodiments, a burner  118  is configured to support the combustion reaction  102  as a flame. 
         [0051]    The propensity of solid and particulate materials to undergo contact electrostatic charging relates, in part, to differences between respective electron affinities characterized as a work function of the solid or particulate materials. When two solid or particulate materials of different work functions are contacted or rubbed together, materials of relatively higher work function tend to acquire electrons and a corresponding negative charge from materials of relatively lower workfunction. Likewise, materials of relatively lower work function tend to acquire a corresponding positive charge by losing electrons to materials of relatively higher work function. For example, according to an embodiment, the contact electrostatic charging material  104  is formed as a conduit from, e.g., a copper nickel alloy having a work function of about 4.7 electron volts, or a polymethylmethacrylate polymer having a work function of about 4.6 electron volts. The charge carrier material can be, e.g., a carbon based solid or particulate fuel, such as coal, with a comparatively lower work function. For example, some coals may have a work function of approximately 3.5 to 3.6 electron volts. Given these values, the charge carrier material, i.e., the coal particulates, acquire a positive charge by losing electrons on contacting or rubbing materials of relatively higher work functions, such as the copper nickel alloy or polymethyl methacrylate. 
         [0052]    The propensity of different materials to undergo contact electrostatic charging is reflected in various reported rankings known as the “triboelectric series”. It should be noted that some “triboelectric series” rankings are reported based on tests conducted under different conditions such as temperature, humidity, surface roughness of materials, particle size, etc. Accordingly, the relative rankings of materials may differ, sometimes substantially, among different reported “triboelectric series” rankings. In many situations, work function values may provide a more consistent characterization for materials employed in contact electrostatic charging of solids or particulates. 
         [0053]    According to an embodiment, the contact electrostatic charging material  104  has a first work function, and the charge carrier material has a second work function. The contact electrostatic charging material  104  is selected such that the first work function is different from the second work function, so that a charge is imparted to the charge carrier material. 
         [0054]    According to various embodiments, the first work function, i.e., the work function of the contact electrostatic charging material  104 , is greater than the second work function, i.e., that of the charge carrier material. The charge carrier feeder  110  is configured to bring the charge carrier material and the contact electrostatic charging material  104  into contact, which imparts the electrostatic charge  106  at a positive polarity to the charge carrier material. Alternatively, the first work function can be less than the second work function, in which case, the electrostatic charge  106  is imparted at a negative polarity to the charge carrier material. 
         [0055]    According to an embodiment, the contact electrostatic charging material  104  is selected such that the first work function is greater or lesser than the second work function by at least about 0.1 electron volts. 
         [0056]    According to various embodiments, the contact electrostatic charging material  104  is selected such that a first work function of the contact electrostatic charging material  104  is different from a coal work function by at least about 0.1 electron volts, i.e., the contact electrostatic charging material  104  is selected such that a first work function of the contact electrostatic charging material  104  is more than about 3.7 electron volts or less than about 3.4 electron volts. Either of these conditions enables the charging mechanism  103  to apply an electrostatic charge to coal as it passes through the burner  118 . 
         [0057]    The contact electrostatic charging material  104  can be any appropriate material, alloy, or formulation, and can include, for example, any of copper, a copper-nickel alloy, brass, aluminum, stainless steel, polytetrafluoroethylene, polymethylmethacrylate, etc. 
         [0058]    According to various embodiments, the contact electrostatic charging material  104  is characterized by a work function of at least about 4.6 electron volts, and is configured to undergo surface electrostatic charging in the presence of a dielectric liquid hydrocarbon fuel. According to another embodiment, the contact electrostatic charging material  104  is selected such that a first work function of the contact electrostatic charging material  104  is at least about 4 electron volts. The contact electrostatic charging material  104  can include, for example, copper, steel, stainless steel, glass, cellulose, fiberglass, polytetrafluoroethylene, polyethylene, polymethylmethacrylate, polyvinylchloride, etc. 
         [0059]      FIG. 6  is a diagram of a system  600  for electrical control of a combustion reaction, according to another embodiment. In previous embodiments, various systems are shown and described in which a charging mechanism  103  is supplies charge carrier material  108  to a a combustion reaction  102  via a burner  118 , or is incorporated as part of the burner. A carrier feeder  110  is positioned in a fuel supply flow path of of the burner  118 , and the charge carrier material  108  is a component of or is entrained by a fuel flow passing through the charging mechanism  103  and the burner  118 . 
         [0060]    According to another embodiment, the charging mechanism  103  is configured to introduce the charge carriers  108  to the combustion reaction  102  at a location that is downstream from the burner  118 . 
         [0061]    For example, as shown in  FIG. 6 , the system  600  is similar in most respects to previous embodiments, except that the charge carrier feeder  110  is configured to introduce the charge carriers  108  to the combustion reaction  102  via a flow of air  602  from a source  604  and supplied to the combustion reaction as an oxidizer. Fuel is provided from a conventional fuel source  606 . The charge carrier material  108  can be premixed with the air flow  602  prior to its introduction to the charge carrier feeder  110 , or the charge carrier material  108  can be provided separately to the charge carrier feeder  110  for mixing with the air flow. 
         [0062]    According to other embodiments, the charge carrier feeder  110  is configured to supply the charge carrier material  108  to the combustion reaction  102  via flue gas that is reintroduced to the combustion reaction as recirculated exhaust gas. 
         [0063]    Various embodiments are described in the present disclosure as including respective different combinations of elements and components, but this is for convenience only. Additional embodiments can be made that include combinations of elements that are described here with respect to separate embodiments, or that include only some of the features or elements of embodiments disclosed here. Further, multiple functions that are described here as being performed by a single element can be performed by respective separate elements, and conversely, the functions of elements that are separately described here can be combined in the operation of a single element. For example, in the embodiment of  FIG. 2 , a controller  206  is disclosed, which is configured to control operation of the electrodynamic system  114 ; a charge carrier feeder controller  304  is described with reference to  FIG. 3A , configured to control operation of a charge carrier feeder  110 ; a contact electrostatic generator controller  308 , described with reference to  FIG. 3B , is configured to control operation of a contact electrostatic generator  306 ; and a controller  408  is described with reference to  FIG. 5 , configured to control operation of a charge carrier collector  402 . According to an embodiment, a controller is provided that is configured to perform the functions of two or more of the various controllers described herein. 
         [0064]      FIGS. 7A-E  are flow diagrams showing various examples of methods  700   a - e  for electrical control of a combustion reaction, according to respective embodiments. 
         [0065]    The method  700   a —includes method steps  702 , imparting a contact electrostatic charge to a charge carrier material. This can be done, for example, by bringing the charge carrier material into contact with a contact electrostatic charging material to produce the charge via triboelectric effect. 
         [0066]    In step  704 , the charge carrier material, including the electrostatic charge, is introduced to a combustion reaction, which imparts a corresponding combustion reaction charge to the combustion reaction. 
         [0067]    In step  706 , an electric field is applied to the combustion reaction, which produces a measurable effect on the combustion reaction, because of the combustion reaction charge. 
         [0068]    According to various embodiments, step  702  includes selecting the charge carrier material. The charge carrier material can include, for example, a solid, a particulate, or a dielectric liquid. 
         [0069]    The charge carrier material can include a fuel that is substantially consumed by the combustion reaction, such as, for example, coal, a dielectric liquid hydrocarbon, a dielectric liquid having a conductivity of less than about 10 nanoSiemens per meter, etc. 
         [0070]    The charge carrier material can include particulates that are substantially nonreactive in the combustion reaction, such as, e.g., quartz or mica. 
         [0071]    According to various embodiments, step  702  includes selecting the contact electrostatic charging material from among appropriate available materials, which can include, for example, a metal, a mineral, a polymer, a glass, a ceramic, etc. 
         [0072]    According to various embodiments, step  702  includes employing a charge carrier feeder that includes an element or structure that itself includes the selected contact electrostatic charging material. The charge carrier feeder can include, for example, a conduit, a chute, a hopper, a conveyor belt, a conveyor screw, a manifold, a venturi, a filter, a separator, a brush, piston, a valve, a nozzle, includes a baffle, a propeller, an impeller, a turbine, a paddle, a fan blade, a propeller housing, an impeller housing, a turbine housing, a fan housing, a mechanical vibrator, a fluidized bed particulate, a fluidized bed chamber wall, a grate, a reservoir, a burner, a fuel source, etc. 
         [0073]    According to an embodiment, step  702  includes selecting the contact electrostatic charging material according to a work function value of the contact electrostatic charging material. According to another embodiment, step  702  includes selecting the charge carrier material according to a work function value of the charge carrier material that is different from a work function value of the contact electrostatic charging material. 
         [0074]    According to an embodiment, step  702  includes selecting the charge carrier material according to a work function value of the charge carrier material that is less than a work function value of the contact electrostatic charging material, such that the electrostatic charge is imparted to the charge carrier material at a positive polarity. 
         [0075]    According to an embodiment, step  702  includes selecting the charge carrier material to have a work function value that is greater than a work function value of the contact electrostatic charging material, such that the electrostatic charge is imparted to the charge carrier material at a negative polarity. 
         [0076]    According to an embodiment, step  702  includes selecting the charge carrier material to have a work function value that is different from a work function value of the contact electrostatic charging material by at least about 0.1 electron volts. 
         [0077]    According to various embodiments, step  702  includes selecting the contact electrostatic charging material to have a work function value that is different from a work function value of coal. Further, the step  702  can include selecting the contact electrostatic charging material to have a work function value that is different from a the work function value of coal by at least about 0.1 electron volts. According to an embodiment, the work function value of the contact electrostatic charging material is greater than about 3.7 electron volts, or, according to another embodiment, less than about 3.4 electron volts. 
         [0078]    According to various embodiments, step  702  includes selecting the contact electrostatic charging material according to a work function value of at least about 4.6 electron volts, selecting the contact electrostatic charging material configured to undergo surface electrostatic charging in the presence of a dielectric liquid hydrocarbon fuel, and/or selecting the contact electrostatic charging material according to a work function value that is at least about 4 electron volts. 
         [0079]    According to various embodiments, step  702  includes selecting the contact electrostatic charging material from among copper, steel, stainless steel, glass, cellulose, fiberglass, polytetrafluoroethylene, polyethylene, polymethylmethacrylate, polyvinylchloride, etc. According to an embodiment, step  702  includes selecting, as the charge carrier material, a dielectric liquid that is characterized by an electrostatic charge relaxation time, and step  704  includes controlling a feeding rate of the charge carrier material to the combustion reaction, such that a travel time of the charge carrier material from the contact electrostatic charging material to the combustion reaction is less than the electrostatic relaxation time. 
         [0080]    According to an embodiment, step  702  includes causing the charge carrier material to impact or rub the contact electrostatic charging material, or to make a sliding or glancing contact, in order to produce the electrostatic charge. 
         [0081]    According to an embodiment, step  704  can include feeding the charge carrier material to the combustion reaction by, for example, employing pneumatic feeding, hydraulic feeding, belt conveying, screw conveying, moving grate feeding, rotary feeding, paddle feeding, rotating conduit feeding, turbocharging, pumping, etc. 
         [0082]    According to various embodiments, step  704  can include increasing, decreasing, or maintaining a feeding rate of the charge carrier material to the combustion reaction. 
         [0083]    According to various embodiments, step  706  includes exposing an electrode to the combustion reaction and driving the electrode to apply the electric field. 
         [0084]    According to an embodiment, step  706  includes selecting continuity between the electrode and ground or another voltage. 
         [0085]    According to an embodiment, step  706  includes applying the electric field at a polarity corresponding to a polarity of a combustion reaction charge. 
         [0086]    According to another embodiment, step  706  includes applying the electric field at a polarity that is opposite the polarity of the combustion reaction charge. 
         [0087]    According to various embodiments, step  708  includes imparting the electrostatic charge using a contact electrostatic generator that comprises the contact electrostatic charging material. The contact electrostatic generator may employ cyclonic tribocharging, static tribocharging, free-fall tribocharging, rotating conduit tribocharging, rotating blade tribocharging, turbo tribocharging, loop tribocharging, belt tribocharging, van de Graaf charging, vibration tribocharging, etc. 
         [0088]    According to an embodiment, step  710  includes controlling the contact electrostatic generator to increase, decrease, or maintain a contact electrostatic charging rate between the contact electrostatic charging material and the charge carrier material. 
         [0089]    According to various embodiments, step  712  includes recovering a portion of the charge carrier material from the combustion reaction or a flue gas of the combustion reaction. Step  714  further includes recycling the recovered charge carrier material to the combustion reaction and/or the charge carrier material feeder. Step  712  can include recovering a portion of the charge carrier material using an electrostatic precipitator a baghouse a conduit a cyclonic particulate separator, a settling chamber, a baffle, etc. According to various embodiments, step  712  includes applying an electric field via one or more recovery electrodes in order to electrostatically recover a portion of the charge carrier material from the combustion reaction or from a flue gas of the combustion reaction. Step  714  can include applying an electric field via the one or more recovery electrodes to electrostatically direct the recovered charge carrier material to the combustion reaction and/or the charge carrier material feeder. 
         [0090]    According to various embodiments, step  716  includes thermally insulating the contact electrostatic charging material from the combustion reaction. 
         [0091]    According to an embodiment, step  718  includes includes electrically insulating the electrostatic charge on the charge carrier material from ground or another voltage. 
         [0092]    According to various embodiments, a further step includes employing a burner configured to support the combustion reaction and to feed the charge carrier material to the combustion reaction. The contact electrostatic charging material can be included in the burner. Step  702  includes contacting the charge carrier material to the contact electrostatic charging material inside the burner to impart the electrostatic charge to the charge carrier material. 
         [0093]    The abstract of the present disclosure is provided as a brief outline of some of the principles of the invention according to one embodiment, and is not intended as a complete or definitive description of any embodiment thereof, nor should it be relied upon to define terms used in the specification or claims. The abstract does not limit the scope of the claims. 
         [0094]    While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.