Ceramic electrode for gliding electric arc

Abstract

A ceramic electrode for a gliding electric arc system. The ceramic electrode includes a ceramic fin defining a spine, a heel, and a tip. A discharge edge of the ceramic fin defines a diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin. A mounting surface coupled to the ceramic fin facilitates mounting the ceramic fin within the gliding electric arc system. One or more ceramic electrodes may be used in the gliding electric arc system or other systems which at least partially oxidize a combustible material.

Description

BACKGROUND

A gliding electric arc is a conventional apparatus for implementing oxidation and reformation reactions to incinerate waste products through full oxidation and to generate synthetic gas (syngas) through partial oxidation, respectively. A gliding electric arc generates an electrical discharge between two or more electrodes.

Oxidation and some reformation reactions are very energetic, resulting in high temperature product streams. While most of the components of an oxidation or reformation reactor structure can be actively cooled, the electrodes cannot easily be cooled due to the position of the electrodes within the reactor and the high voltage imposed on the electrodes. Additionally, the electrodes are immersed in the reactant stream, resulting in high heat flux conditions that increase the difficulty of cooling the electrodes.

Electrodes are conventionally fabricated from metal sheet using well-established machining techniques. Metals electrodes are used for their electric current carrying properties and their relatively simple manufacturing process. However, metal electrodes have maximum operating temperature limits, particularly in an oxidation implementation. These operating temperature limits are substantially below the temperatures reached in the oxidation product stream. As a result, the metal electrodes can oxidize and melt because of the temperature of the oxidation product stream.

SUMMARY

A ceramic electrode for a gliding electric arc system is disclosed. The ceramic electrode includes a ceramic fin defining a spine, a heel, and a tip. A discharge edge of the ceramic fin defines a diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin. A mounting surface coupled to the ceramic fin facilitates mounting the ceramic fin within the gliding electric arc system. One or more ceramic electrodes may be used in the gliding electric arc system or other systems which at least partially oxidize a combustible material.

Embodiments of a method are also described. In one embodiment, the method is a method for fabricating a ceramic electrode. An embodiment of the method includes fabricating a ceramic fin which includes a spine, a heel, a tip, and a discharge edge. The discharge edge defines a diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin. The method also includes implementing a densification operation to densify the ceramic fin. Other embodiments of the method are also described.

Embodiments of a system are also described. In one embodiment, the system is a gliding electric arc system. An embodiment of the system includes a plasma zone to generate a plasma. The system also includes at least one channel to direct a combustible material and an oxidizer into the plasma zone. The system also includes a plurality of electrically conductive ceramic electrodes within the plasma zone. The plurality of electrically conductive ceramic electrodes generates the plasma to at least partially oxidize the combustible material. Other embodiments of the system are also described.

Other aspects and advantages of embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which are illustrated by way of example of the various principles and embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a schematic block diagram of one embodiment of a combustion system for oxidizing a combustible material.

FIG. 1B illustrates a schematic block diagram of another embodiment of a combustion system for oxidizing a combustible material.

FIG. 2 illustrates a schematic block diagram of one embodiment of the gliding electric arc system of the combustion system of FIG. 1A.

FIGS. 3A-C illustrate schematic diagrams of a non-thermal plasma generator of the gliding electric arc system of FIG. 2.

FIG. 4 illustrates a schematic diagram of another embodiment of the gliding electric arc system.

FIG. 5 illustrates a schematic diagram of another embodiment of the gliding electric arc system.

FIGS. 6A-C illustrate schematic diagrams of another embodiment of the gliding electric arc system.

FIGS. 7A and 7B illustrate schematic diagrams of additional perspective views of the gliding electric arc system of FIGS. 6A-C.

FIG. 8A illustrates a schematic block diagram of an embodiment of the gliding electric arc system of FIG. 4 within a furnace.

FIG. 8B illustrates a schematic block diagram of an embodiment of the gliding electric arc system of FIG. 5 within a furnace.

FIG. 9A illustrates a schematic diagram of an embodiment of a ceramic electrode for use with any of the gliding electric arc systems of the previous figures.

FIG. 9B illustrates a schematic diagram of another embodiment of a ceramic electrode for use with any of the gliding electric arc systems of the previous figures.

FIG. 10 illustrates a schematic flow chart diagram of one embodiment of a method of making a ceramic electrode such as the ceramic electrodes of FIGS. 9A and 9B.

Throughout the description, similar reference numbers may be used to identify similar elements.

DETAILED DESCRIPTION

In the following description, specific details of various embodiments are provided. However, some embodiments may be practiced with less than all of these specific details. In other instances, certain methods, procedures, components, structures, and/or functions are described in no more detail than to enable the various embodiments of the invention, for the sake of brevity and clarity.

FIG. 1A illustrates a schematic block diagram of one embodiment of an incineration system 100 for incineration a medical waste material. Although many examples within this description relate to the incineration system 100 of FIG. 1, embodiments of the invention may be used in various systems which are used to at least partially oxidize a combustible material. Hence, although some embodiments facilitate incineration of a material through substantially complete oxidation of the material, other exemplary systems may implement another variation of oxidation or reformation (i.e., partial oxidation) of a combustible material.

The illustrated oxidation system includes a medical waste source 102, a gliding electric arc incineration system 104, an oxidizer source 106, and an oxidizer controller 108. Although certain functionality is described herein with respect to each of the illustrated components of the incineration system 100, other embodiments of the incineration system 100 may implement similar functionality using fewer or more components. Additionally, some embodiments of the incineration system 100 may implement more or less functionality than is described herein.

In one embodiment, the medical waste source 102 supplies a biological or medical waste material to the gliding arc electric incineration system 104. The biological or medical waste material may be, for example, in liquid or solid form. However, the content and composition of the waste material that may be incinerated using the incineration system 100 is not limited. In one embodiment, the waste material is human tissues and organs removed during a medical treatment process. In another embodiment, the waste material is a living or dead biological material resulting from medical research activities. Additionally, in some embodiments, the biological or medical waste material may be introduced to the gliding electric arc incineration system 104 using a carrier material. For example, the biological or medical waste material may be entrained with a liquid or a gas, and the combination of the waste material and the carrier material is introduced into the gliding electric arc incineration system 104.

In one embodiment, the gliding electric arc incineration system 104 is a high energy plasma arc system. Additionally, some embodiments of the gliding electric arc incineration system 104 are referred to as non-thermal plasma generators or systems because the process employed by the gliding electric arc incineration system 104 does not provide a substantial heat input (e.g., compared to conventional incineration systems) for the incineration reaction. It should also be noted that, although the illustrated incineration system 100 includes a gliding electric arc incineration system 104, other embodiments of the incineration system 100 may include other types of non-thermal plasma generators.

In order to facilitate the incineration process implemented by the gliding electric arc incineration system 104, the oxidizer source 106 supplies an oxidizer, or oxidant, to the gliding electric arc incineration system 104. In one embodiment, the oxidizer controller 108 controls the amount of oxidizer such as oxygen that is supplied to gliding electric arc incineration system 104. For example, the oxidizer controller 108 may control the flow rate of the oxidizer from the oxidizer source 106 to the gliding electric arc incineration system 104. The oxidizer may be air, oxygen, steam (H₂O), or another type of oxidizer. In some embodiments, oxygen may be used instead of air in order to lower the overall volume of oxidized gas. Embodiments of the oxidizer controller 108 include a manually controlled valve, an electronically controlled valve, a pressure regulator, an orifice of specified dimensions, or another type of flow controller. Another embodiment of the oxidizer controller 108 incorporates an oxidant composition sensor feedback system.

In one embodiment, the oxidizer mixes with the waste material within the gliding electric arc incineration system 104. Alternatively, the waste material and the oxidizer may be premixed before the mixture is injected into the gliding electric arc incineration system 104. Additionally, the oxidizer, the waste material, or a mixture of the oxidizer and the waste material may be preheated prior to injection into the gliding electric arc incineration system 104.

In general, the gliding electric arc incineration system 104 oxidizes the waste material and outputs an incineration product that is free or substantially free of harmful materials. More specific details of the incineration process are described below with reference to the following figures. It should be noted that the incineration process depends, at least in part, on the amount of oxidizer that is combined with the waste material and the temperature of the reaction. In some instances, it may be beneficial to input heat into the gliding electric arc incineration system 104 to increase the effectiveness of the incineration process.

In one embodiment, full oxidation (referred to simply as oxidation) of the waste material produces an incineration product. Full oxidation occurs when the amount of oxygen used in the incineration reaction is more than a stoichiometric amount of oxygen. In some embodiments, 5-100% excess of stoichiometric oxygen levels are used to implement full oxidation within the incineration process. An exemplary oxidation equation is:

${\mathrm{CH}}_n+\left(1+\frac{n}{4}\right)O_2\to {\mathrm{CO}}_2+\frac{n}{2}{H}_{2}O$

Other equations may be used to describe other types of reformation and oxidation processes.

The incineration process implemented using the gliding electric arc incineration system 104 may be endothermic or exothermic. In some instances, given the composition of biological and medical waste material, heat may be input into the gliding electric arc system 104 to facilitate incineration. For example, it may be useful to maintain part or all of the gliding electric arc incineration system 104 at an operating temperature within an operating temperature range for efficient operation of the gliding electric arc incineration system 104. In one embodiment, the gliding electric arc incineration system 104 is mounted within a furnace (refer to FIGS. 8A and 8B) during operation to maintain the operating temperature of the gliding electric arc incineration system 100 within an operating temperature range of approximately 700° C. to 1000° C. Other embodiments may use other operating temperature ranges.

Alternatively, or in addition to generally heating the gliding electrical arc incineration system 104, some embodiments of the incineration system 100 may preheat the medical waste material from the medical waste source 102, the oxidizer from the oxidizer source 106, or both. The waste material and/or the oxidizer may be preheated individually at the respective sources or at some point prior to entering the gliding electric arc incineration system 104. For example, the waste material may be preheated within the medical waste channel which couples the medical waste source 102 to the gliding electric arc incineration system 104. Alternatively, the waste material and/or the oxidizer may be preheated individually within the gliding electric arc incineration system 104. In another embodiment, the waste material and the oxidizer may be mixed and preheated together as a mixture before or after entering the gliding electric arc incineration system 104.

FIG. 1B illustrates a schematic block diagram of another embodiment of an incineration system 110 for incinerating a medical waste material. Although certain functionality is described herein with respect to each of the illustrated components of the incineration system 110, other embodiments of the incineration system 110 may implement similar functionality using fewer or more components. Additionally, some embodiments of the incineration system 110 may implement more or less functionality than is described herein.

The illustrated incineration system 110 shown in FIG. 1B is substantially similar to the incineration system 100 shown in FIG. 1A, except that the incineration system 110 shown in FIG. 1B also includes a mixing chamber 112. The mixing chamber 112 is coupled between the medical waste source 102 and the gliding electric arc incineration system 104. The mixing chamber 112 is also coupled to the oxidizer source 106, for example, via the oxidizer controller 108. In one embodiment, the mixing chamber 112 facilitates premixing the waste material and the oxidizer prior to introduction into the gliding electric arc incineration system 104. In some embodiments, the mixing chamber 112 may be a separate chamber coupled to conduits connected to the medical waste source 102, the gliding electric arc incineration system 104, and the oxidizer controller 108. In other embodiments, the mixing chamber 112 may be a shared channel, or conduit, to jointly transfer the waste material and the oxidizer to the gliding electric arc incineration system 104.

FIG. 2 illustrates a schematic block diagram of one embodiment of the gliding electric arc incineration system 104 of the incineration system 100 of FIG. 1A. The illustrated gliding electric arc incineration system 104 includes a preheat zone 113, a plasma zone 114, a post-plasma reaction zone 116, and a heat transfer zone 118. Although four separate functional zones are described, some embodiments may implement the functionality of two or more zones at approximately the same time and/or in approximately the same physical proximity. For example, heat transfer corresponding to the illustrated heat transfer zone 118 may occur during plasma generation corresponding to the plasma zone 114. Similarly, heat transfer corresponding to the heat transfer zone 118 may occur in approximately the same location as post-plasma reactions corresponding to the post-plasma reaction zone 116.

In one embodiment, the waste material and the oxidizer are introduced into the preheat zone 113. Within the preheat zone 113, the waste material and the oxidizer are preheated (represented by the heat transfer Q₁) individually or together. In an alternative embodiment, one or both of the waste material and the oxidizer may bypass the preheat zone 113. The waste material and the oxidizer then pass to the plasma zone 114 from the preheat zone 113 (or pass directly to the plasma zone from the respective sources, bypassing the preheat zone 113). Within the plasma zone, the waste material is at least partially incinerated by a non-thermal plasma generator (refer to FIGS. 3A-C) such as a gliding electric arc. The non-thermal plasma generator acts as a catalyst to initiate the oxidation process to incinerate the waste material. More specifically, the non-thermal plasma generator ionizes, or breaks apart, one or more of the reactants to create reactive elements.

After ionization, the reactants pass to the post-plasma reaction zone 116, which facilitates homogenization of the oxidized composition. Within the post-plasma reaction zone 116, some of the reactants and the products of the reactants are oxygen rich while others are oxygen lean. A homogenization material such as a solid state oxygen storage compound within the post-plasma reaction zone 116 acts as a chemical buffering compound to physically mix, or homogenize, the oxidation reactants and products. Hence, the oxygen storage compound absorbs oxygen from oxygen-rich packets and releases oxygen to oxygen-lean packets. This provides both spatial and temporal mixing of the reactants to help the reaction continue to completion. In some embodiments, the post-plasma reaction zone 116 also facilitates equilibration of gas species and transfer of heat.

The heat transfer zone 118 also facilitates heat transfer (represented by the heat transfer Q₂) from the incineration product to the surrounding environment. In some embodiments, the heat transfer zone 118 is implemented with passive heat transfer components which transfer heat, for example, from the oxidation product to the homogenization material and to the physical components (e.g., housing) of the gliding electrical arc incineration system 104. Other embodiments use active heat transfer components to implement the heat transfer zone 118. For example, forced air over the exterior surface of a housing of the gliding electric arc oxidation system 104 may facilitate heat transfer from the housing to the nearby air currents. As another example, an active stream of a cooling medium may be used to quench an oxidation product. In another embodiment, the gliding electric arc incineration system 104 may be configured to facilitate heat transfer from the heat transfer zone 118 to the preheat zone 113 to preheat the waste material and/or the oxidizer.

FIGS. 3A-C illustrate schematic diagrams of a non-thermal plasma generator 120 of the gliding electric arc incineration system 104 of FIG. 2. The depicted non-thermal plasma generator 120 includes a pair of ceramic electrodes 122. However, other embodiments may include more than two ceramic electrodes 122. For example, some embodiments of the plasma generator 120 include three ceramic electrodes 122. Other embodiments of the plasma generator 120 include six ceramic electrodes 122 or another number of ceramic electrodes 122. Each ceramic electrode 122 is coupled to an electrical conductor (not shown) to provide an electrical signal to the corresponding ceramic electrode 122. Where multiple ceramic electrodes 122 are implemented, some ceramic electrodes 122 may be coupled to the same electrical conductor so that they are on the same phase of a single-phase or a multi-phase electrical distribution system. A more detailed embodiment of a ceramic electrode 122 is shown in FIG. 9A and described in more detail below.

In one embodiment, one or more of the ceramic electrodes 122 are made of silicon carbide (SiC). In another embodiment, one or more of the ceramic electrodes 122 are made of lanthanum chromite (LaCrO₃). It will be appreciated by those of skill in the art that other suitable electrically conductive ceramics may be used for the electrodes 122.

The electrical signals on the ceramic electrodes 122 produce a high electrical field gradient between each pair of ceramic electrodes 122. For example, if there is a separation of 2 millimeters between a pair of ceramic electrodes 122, the electrical potential between the ceramic electrodes 122 is about 6-9 kV.

The mixture of the waste material and the oxidizer enters and flows axially through the plasma generator 120 (in the direction indicated by the arrow). The high voltage between the ceramic electrodes 122 ionizes the mixture of reactants, which allows current to flow between the ceramic electrodes 122 in the form of an arc 124, as shown in FIG. 3A. Because the ions of the reactants are in an electric field having a high potential gradient, the ions begin to accelerate toward one of the ceramic electrodes 122. This movement of the ions causes collisions which create free radicals. The free radicals initiate a chain reaction for incineration of the waste material.

Due to the flow of the mixture into the plasma generator 120, the ionized particles are forced downstream, as shown in FIG. 3B. Since the ionized particles form the least resistive path for the current to flow, the arc 124 also moves downstream (as indicated by the arrow) and spreads out to follow the contour of the diverging edges of the ceramic electrodes 122. Although the edges of the ceramic electrodes 122 are shown as elliptical contours, other variations of diverging contours may be implemented, as explained below with reference to FIG. 9B. As the arc 124 moves downstream, the effect of the reaction is magnified relative to the size of the arc 124.

Eventually, the gap between the ceramic electrodes 122 becomes wide enough that the current ceases to flow between the ceramic electrodes 122. However, the ionized particles continue to move downstream under the influence of the mixture. Once the current stops flowing between the ceramic electrodes 122, the electrical potential increases on the ceramic electrodes 122 until the current arcs again, as shown in FIG. 3C, and the plasma generation process continues. Although much of the oxidation process may occur at the plasma generator 120 between the ceramic electrodes 122, the oxidation process may continue downstream from the plasma generator 120.

FIG. 4 illustrates a schematic diagram of another embodiment of the gliding electric arc incineration system 130. The illustrated gliding electric arc incineration system 130 includes a plasma generator 120. Each of the ceramic electrodes 122 of the plasma generator 120 is connected to an electrical conductor 132. The plasma generator 120 is located within a housing 134. In one embodiment, the housing 134 defines a channel 136 downstream of the plasma generator 120 so that the reactants may continue to react and form the oxidation product downstream of the plasma generator 120. The housing 134 may be fabricated of a conductive or non-conductive material. In either case, an electrically insulated region may be provided around the plasma generator 120. In one embodiment, the housing 134 is fabricated from a non-conductive material such as an alumina ceramic to prevent electricity from discharging from the plasma generator 120 to surrounding conductive components.

In order to introduce the waste material and the oxidizer into the plasma generator 120, the gliding electric arc incineration system 130 includes multiple channels, or conduits. In the illustrated embodiment, the gliding electric arc incineration system 130 includes a first channel 138 for the waste material and a second channel 140 for the oxidizer. The first channel is also referred to as the medical waste channel, and the second channel is also referred to as the oxidizer channel. The medical waste and oxidizer channels 138 and 140 join at a mixing manifold 142, which facilitates premixing of the waste material and the oxidizer. In other embodiments, the waste material and the oxidizer may be introduced separately into the plasma generator 120. Additionally, the locations of the medical waste and oxidizer channels 138 and 140 may be arranged in a different configuration.

In order to contain the reactants during the incineration process, and to contain the incineration product resulting from the incineration process, the plasma generator 120 and the housing 134 may be placed within an outer shell 144. In one embodiment, the outer shell 144 facilitates heat transfer to and/or from the gliding electric arc incineration system 130. Additionally, the outer shell 144 is fabricated from steel or another material having sufficient strength and stability at the operating temperatures of the gliding electric arc incineration system 130.

In order to remove the incineration product (e.g., including any carbon dioxide, steam, etc.) from the annular region 146 of the outer shell 144, the gliding electric arc incineration system 130 includes an exhaust channel 148. In one embodiment, the exhaust channel is coupled to a collector ring manifold 150 that circumscribes the housing 134 and has one or more openings to allow the incineration product to flow to the exhaust channel 148. In the illustrated embodiment, the incineration product is exhausted out the exhaust channel 148 at approximately the same end as the intake channels 138 and 140 for the waste material and the oxidizer. This configuration may facilitate easy maintenance of the gliding electric arc incineration system 130 since all of the inlet, outlet, and electrical connections are in about the same place. Other embodiments of the gliding electric arc incineration system 130 may have alternative configurations to exhaust the incineration products from the outer shell 144.

The illustrated gliding electric arc incineration system 130 also includes a heater (not shown) coupled to the medical waste channel 138. In one embodiment, the heater preheats the medical waste material within the medical waste channel 138 before the medical waste material enters the plasma zone of the gliding electric arc incineration system 130.

FIG. 5 illustrates a schematic diagram of another embodiment of the gliding electric arc incineration system 160. Although many aspects of the gliding electric arc incineration system 160 of FIG. 5 are substantially similar to the gliding electric arc incineration system 130 of FIG. 4, the gliding electric arc incineration system 160 is different in that it allows pass-through exhaustion of the incineration product through an exhaust outlet 162 at approximately the opposite end of the gliding electric arc incineration system 160 from the intake channels 138 and 140 for the waste material and the oxidizer. In one embodiment, the incineration product passes directly through the channel 136 of the housing 134 and out through the exhaust outlet 162, instead of passing into the annular region 146 of the outer shell 144.

The illustrated gliding electric arc incineration system 160 of FIG. 5 also includes some additional distinctions from the gliding electric arc incineration system 130 of FIG. 4. In particular, the gliding electric arc incineration system 160 includes a diversion plug 164 located within the housing 134 to divert the reactants and incineration product outward toward the interior surface of a wall of the housing 134. For an incineration process that is exothermic, the diversion plug 164 forces the flow toward the wall of the housing 134 to facilitate heat transfer from the incineration product to the wall of the housing 134. In one embodiment, the diversion plug 164 is fabricated from a ceramic material or another material that is stable at high temperatures.

In another embodiment, the gliding electric arc incineration system 160 facilitates heat transfer to the plasma zone, for example, to facilitate an endothermic incineration process. The illustrated gliding electric arc incineration system 160 includes a heat source (not shown) coupled to the outer shell 144. The heat source supplies a heating agent in thermal proximity to the outer wall of the housing 134 (e.g., within the annular region 146 of the outer shell 144) to transfer heat from the heating agent to the plasma zone of the gliding electric arc incineration system 160. The heating agent may be a gas or a liquid. For example, the heating agent may be air. Although not shown in detail, the heating agent may be circulated within or exhausted from the outer shell 144.

In one embodiment, the gliding electric arc incineration system 160 is initially heated by introducing a mixture of a gaseous hydrocarbon and air. Exemplary gaseous hydrocarbons include natural gas, liquefied petroleum gas (LPG), propane, methane, and butane. Once the temperature of the gliding electric arc oxidation system 160 reaches an operating temperature of about 800° C., the flow of the gaseous hydrocarbon is turned off and waste material is introduced. The flow rates of oxidizer and waste material are adjusted to maintain a proper stoichiometric ratio, while the total flow is adjusted to maintain the plasma generator 120 at a particular operating temperature or within an operating temperature range.

The illustrated gliding electric arc oxidation system 160 also includes a homogenization material 166 located in the channel 136 of the housing 134. The homogenization material 166 serves one or more of a variety of functions. In some embodiments, the homogenization material 166 facilitates homogenization of the incineration product by transferring oxygen from the oxidizer to the waste material. In some embodiments, the homogenization material 166 also provides both spatial and temporal mixing of the reactants to help the reaction continue to completion. In some embodiments, the homogenization material 166 also facilitates equilibration of gas species. In some embodiments, the homogenization material 166 also facilitates heat transfer, for example, from the incineration product to the homogenization material 166 and from the homogenization material 166 to the housing 134. In some embodiments, the homogenization material 166 may provide additional functionality.

The illustrated gliding electric arc incineration system 160 also includes a ceramic insulator 168 to electrically insulate the ceramic electrodes 122 from the housing 134. Alternatively, the gliding electric arc incineration system 160 may include an air gap between the ceramic electrodes 122 and the housing 134. While the dimensions of the air gap may vary in different implementations depending on the operating electrical properties and the fabrication materials used, the air gap should be sufficient to provide electrical isolation between the ceramic electrodes 122 and the housing 134 so that electrical current does not arc from the ceramic electrodes 122 to the housing 134.

FIGS. 6A-C illustrate schematic diagrams of various perspective views of another embodiment of the gliding electric arc incineration system 170. In particular, FIG. 6A illustrates the outer shell 144 having a flange 172 mountable to a furnace or other surface. A second flange 174 may be attached to at least some of the internal components described above, allowing the internal components to be removed from the outer shell 144 without removing or detaching the outer shell 144 from a mounted position. The channels 138 and 140 for the waste material and the oxidizer and the exhaust channel 148 are also indicated.

FIG. 6B shows a cutaway view of the outer shell 144, the housing 134, the waste channel 138 (the channels 140 and 148 are not shown), the collector ring manifold 150, and the flanges 172 and 174. The illustrated embodiment also includes an oxidizer coil 176 which is coupled to the oxidizer channel 140. The oxidizer coil 176 is part of a preheat channel portion which extends into the flow path of the incineration product. In this way, heat may transfer from the incineration product to the oxidizer within the oxidizer coil 176 to preheat the oxidizer. In other words, the oxidizer coil 176 receives heat from the incineration process in order to preheat the oxidizer before it is mixed with the waste material. In an alternative embodiment, a similar coil or other structure may be used to preheat the waste material or a combination of the waste material and the oxidizer. FIG. 6C also shows the housing 134, the channels 138 and 148 (the channel 140 is not shown), the collector ring manifold 150, the flanges 172 and 174, and the oxidizer coil 176. The illustrated embodiment also includes a first channel extension 178A to couple the oxidizer channel 140 to the oxidizer coil 176 and a second channel extension 178B to deliver the preheated oxidizer from the oxidizer coil 176 to the plasma zone of the gliding electric arc incineration system 170.

FIGS. 7A and 7B illustrate schematic diagrams of additional perspective views of the gliding electric arc incineration system 170 of FIGS. 6A-C. In particular, FIGS. 7A and 7B illustrate embodiments of the waste and oxidizer channels 138 and 140, the exhaust channel 148, the mixing manifold 142, the collector ring manifold 150, and the flanges 172 and 174. The channel extensions 178A and 178B are also shown. Additionally, the gliding electric arc incineration system 130 includes several support bars 182 connected to a bottom mounting plate 184 to support the mixing manifold 142. In one embodiment, the bottom mounting plate 184 includes apertures 186 to accommodate the electrical conductors 132. In some embodiments, the electrical conductors 132 also provide structural support for the ceramic electrodes 122 to which they are connected. For example, the electrical conductors 132 may pass through cutout regions 188 defined by the mixing manifold 142, without touching the mixing manifold 142, to support the ceramic electrodes 122 at a distance from the mixing manifold 142. In one embodiment, the conductors 312 are surrounded by electrical insulators at the apertures 186 to prevent electricity from discharging to the bottom mounting plate 184.

In some embodiments, the bottom mounting plate 184 may be removed from the flanges 172 and 174 to remove the mixing manifold 142 and the ceramic electrodes 122 from the housing 134 and the outer shell 144. Additionally, in some embodiments, one or more notches 190 are formed in the bottom mounting plate 184 to facilitate proper alignment of the mixing manifold 142 with the channels 138 and 140.

FIG. 8A illustrates a schematic block diagram of an embodiment of the gliding electric arc incineration system 130 of FIG. 4 within a furnace 192. Similarly, FIG. 8B illustrates a schematic block diagram of an embodiment of the gliding electric arc incineration system 160 of FIG. 5 within a furnace 192. As explained above, it may be useful to mount embodiments of the gliding electric arc incineration systems 130, 160, and 170 inside a furnace 192 to maintain the gliding electric arc incineration systems 130, 160, and 170 at a temperature within a particular operating temperature.

FIG. 9A illustrates a schematic diagram of an embodiment of a ceramic electrode 122 for use with any of the gliding electric arc systems of the previous figures. The illustrated ceramic electrode 122 includes a fin 200, which has a spine 202 and a discharge edge 204. The discharge edge 204 includes a heel 206 and a tip 208. Additionally, the discharge edge 204 tapers toward the spine 202 as the discharge edge 204 proceeds from the heel 206 to the tip 208. In this way, the discharge edge 204 defines a diverging profile (i.e., diverging away from the electric arc zone between ceramic electrode pairs) approximately from the heel 206 to the tip 208. In one embodiment, the discharge edge 204 defines an elliptical profile that is consistent with a portion of an ellipse. Alternatively, the discharge edge 204 may define another non-linear, diverging profile.

Additionally, it should be noted that the discharge edge 204 may be a tapered discharge edge which tapers from the thickness of the ceramic fin 200 to a thinner edge at the discharge edge. In other words, the discharge edge 204 may taper to a sharp edge, or point, similar to a cutting knife.

The illustrated ceramic electrode 122 also includes a mounting surface 210 which is coupled to the ceramic fin 200. In one embodiment, the mounting surface 210 facilitates mounting the ceramic fin 200 within a gliding electric arc system, as described above. As one example, the mounting surface 210 may include one or more mounting holes 212 through which mounting screws (not shown) may be attached. Alternatively, the mounting surface 210 may facilitate another type of mounting such as friction fit, snap fit, adhesion, or another type of mounting. Also, in one embodiment, the mounting surface 210 may be defined by a mounting tab that extends substantially perpendicular (or at another angle) from the ceramic fin 200. The ceramic tab may be formed integrally with the ceramic fin 200 or, alternatively, may be formed separately and attached to the ceramic fin 200.

The ceramic fin 200 is made of an electrically conductive ceramic material in order to facilitate generation of an electrical arc during the plasma reformation process described above. In one embodiment, the ceramic fin 200 is made out of a metal oxide material. As one example, the ceramic fin 200 may be made out of a perovskite material such as a magnesium-doped lanthanum chromite material. In other embodiments, the ceramic fin 200 may be made out of a silicon carbide material or another type of conductive material.

FIG. 9B illustrates a schematic diagram of another embodiment of a ceramic electrode 220 for use with any of the gliding electric arc systems of the previous figures. In many aspects, the ceramic electrode 220 is substantially similar to the ceramic electrode 122 of FIG. 9A. However, the ceramic electrode 220 defines a substantially linear discharge edge 222, rather than a substantially non-linear discharge edge 204. Otherwise, the ceramic electrode 220 is substantially similar to the ceramic electrode 122. Other embodiments of ceramic electrodes also may be implemented, instead of or in addition to the ceramic electrodes 122 and 220 shown in FIGS. 9A and 9B.

FIG. 10 illustrates a schematic flow chart diagram of one embodiment of a method 230 of making a ceramic electrode such as the ceramic electrodes 122 and 220 of FIGS. 9A and 9B. In the illustrated embodiment, the method 230 includes fabricating 232 a ceramic fin 200 with a spine 202, a heel 206, a tip 208, and a discharge edge 204. In one embodiment, fabricating the ceramic fin 200 includes tape casting and laser cutting the ceramic fin 200. Alternatively, fabricating the ceramic fin 200 includes dry pressing the ceramic fin 200. In other embodiments, fabricating the ceramic fin 200 includes slip casting a ceramic fin 200 or mechanical punching the ceramic fan 200. Other ceramic fabrication processes also may be used.

After the ceramic fin 200 is fabricated, the ceramic fin 200 is then densified 234. In one embodiment, densifying the ceramic fin 200 includes sintering the ceramic fin 200. For example, pressureless sintering may be used to densify the ceramic fin 200. In another embodiment, densifying the ceramic fin 200 includes hot pressing the ceramic fin 200. For example, hot isostatic pressing may be used to densify the ceramic fin 200. Other ceramic densification processes also may be used.

Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that the described feature, operation, structure, or characteristic may be implemented in at least one embodiment. Thus, the phrases “in one embodiment,” “in an embodiment,” and similar phrases throughout this specification may, but do not necessarily, refer to the same embodiment.

Furthermore, the described features, operations, structures, or characteristics of the described embodiments may be combined in any suitable manner. Hence, the numerous details provided here, such as examples of electrode configurations, housing configurations, substrate configurations, channel configurations, catalyst configurations, and so forth, provide an understanding of several embodiments of the invention. However, some embodiments may be practiced without one or more of the specific details, or with other features operations, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in at least some of the figures for the sake of brevity and clarity.

Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims appended hereto and their equivalents.

Claims

1. A ceramic electrode for a gliding electric arc system, the ceramic electrode comprising: a ceramic fin defining a spine, a heel, and a tip, wherein the heel is defined by an angular point between two discrete edges of the ceramic fin which meet at an acute angle;a discharge edge of the ceramic fin, the discharge edge defining a diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin; anda mounting surface coupled to the ceramic fin, the mounting surface to facilitate mounting the ceramic fin within the gliding electric arc system.

2. The ceramic electrode of claim 1, wherein the discharge edge of the ceramic fin defines a non-linear diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin.

3. The ceramic electrode of claim 1, wherein the discharge edge of the ceramic fin defines a linear diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin.

4. The ceramic electrode of claim 1, wherein the ceramic fin comprises a metal oxide fin.

5. The ceramic electrode of claim 4, wherein the metal oxide fin comprises fin having a material with a perovskite structure.

6. The ceramic electrode of claim 5, wherein the perovskite fin comprises a magnesium-doped lanthanum chromite fin.

7. The ceramic electrode of claim 1, wherein the ceramic fin comprises a silicon carbide fin.

8. The ceramic electrode of claim 1, wherein the discharge edge of the ceramic fin comprises a tapered discharge edge which tapers from a thickness of the ceramic fin outward to a thinner edge at the discharge edge.

9. The ceramic electrode of claim 1, further comprising a mounting tab coupled to the ceramic fin, the mounting tab extending substantially perpendicular from the ceramic fin to define the mounting surface for mounting the ceramic fin within the gliding electric arc system.

10. The ceramic electrode of claim 9, wherein the mounting tab is integral with the ceramic fin.

11. The ceramic electrode of claim 1, wherein the ceramic fin comprises an electrically conductive ceramic material.

12. A gliding electric arc system, the system comprising: a plasma zone to generate a plasma;at least one channel to direct a combustible material and an oxidizer into the plasma zone; anda plurality of electrically conductive ceramic electrodes within the plasma zone, the plurality of electrically conductive ceramic electrodes to generate the plasma to at least partially oxidize the combustible material;wherein each of the electrically conductive ceramic electrodes comprises a ceramic fin with a heel that is defined by an angular point between two discrete edges of the ceramic fin which meet at an acute angle.

13. The system of claim 12, wherein the plurality of electrically conductive ceramic electrodes comprises metal oxide electrodes, the metal oxide electrodes to at least partially oxidize the combustible material in the plasma with a low-oxygen concentration below a stoichiometric amount of oxygen.

14. The system of claim 13, wherein the metal oxide electrodes comprise magnesium-doped lanthanum chromite electrodes.

15. The system of claim 12, wherein the plurality of electrically conductive ceramic electrodes comprises silicon carbide electrodes, the silicon carbide electrodes to at least partially oxidize the combustible material in the plasma with a high-oxygen concentration above a stoichiometric amount of oxygen.

16. The system of claim 12, wherein each of the electrically conductive ceramic electrodes comprises a diverging discharge edge between the heel and a tip, wherein the diverging discharge edge diverges away from the other electrically conductive ceramic electrodes in a direction of a flow of the plasma through the plasma zone.

17. The system of claim 12, wherein each of the electrically conductive ceramic electrodes comprises a mounting tab to define a mounting surface for mounting the electrically conductive ceramic electrode within the plasma zone.

18. A ceramic electrode for a gliding electric arc system, the ceramic electrode comprising: a ceramic fin defining a spine, a heel, and a tip;a discharge edge of the ceramic fin, the discharge edge defining a diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin; anda mounting tab coupled to the ceramic fin, the mounting tab extending substantially perpendicular from the ceramic fin to define a mounting surface for mounting the ceramic fin within the gliding electric arc system.

19. The ceramic electrode of claim 18, wherein the discharge edge of the ceramic fin defines a non-linear diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin.

20. The ceramic electrode of claim 18, wherein the discharge edge of the ceramic fin defines a linear diverging profile approximately from the heel of the ceramic fin to the tip of the ceramic fin.

21. The ceramic electrode of claim 18, wherein the ceramic fin comprises a metal oxide fin.

22. The ceramic electrode of claim 21, wherein the metal oxide fin comprises a perovskite fin.

23. The ceramic electrode of claim 22, wherein the perovskite fin comprises a magnesium-doped lanthanum chromite fin.

24. The ceramic electrode of claim 18, wherein the ceramic fin comprises a silicon carbide fin.

25. The ceramic electrode of claim 18, wherein the discharge edge of the ceramic fin comprises a tapered discharge edge which tapers from a thickness of the ceramic fin outward to a thinner edge at the discharge edge.

26. The ceramic electrode of claim 18, wherein the mounting tab is integral with the ceramic fin.

27. The ceramic electrode of claim 18, wherein the ceramic fin comprises an electrically conductive ceramic material.

28. A gliding electric arc system, the system comprising: a plasma zone to generate a plasma;at least one channel to direct a combustible material and an oxidizer into the plasma zone; anda plurality of electrically conductive ceramic electrodes within the plasma zone, the plurality of electrically conductive ceramic electrodes to generate the plasma to at least partially oxidize the combustible material;wherein each of the electrically conductive ceramic electrodes comprises a ceramic fin and a mounting tab, the mounting tab extending substantially perpendicular from the ceramic fin to define a mounting surface for mounting the electrically conductive ceramic electrode within the plasma zone.

29. The system of claim 28, wherein the plurality of electrically conductive ceramic electrodes comprises metal oxide electrodes, the metal oxide electrodes to at least partially oxidize the combustible material in the plasma with a low-oxygen concentration below a stoichiometric amount of oxygen.

30. The system of claim 29, wherein the metal oxide electrodes comprise magnesium-doped lanthanum chromite electrodes.

31. The system of claim 28, wherein the plurality of electrically conductive ceramic electrodes comprises silicon carbide electrodes, the silicon carbide electrodes to at least partially oxidize the combustible material in the plasma with a high-oxygen concentration above a stoichiometric amount of oxygen.

32. The system of claim 28, wherein each of the electrically conductive ceramic electrodes comprises a diverging discharge edge which diverges away from the other electrically conductive ceramic electrodes in a direction of a flow of the plasma through the plasma zone.