Abstract:
The present general inventive concept discloses a ceramic composite substrate that, with proper construction and proper excitation, can generate uniform plasma throughout the substrate for fluid flow treatment to influence a change in its chemical, electrical or physical properties, and method for generating plasma throughout the substrate. The ceramic substrate can include fibrous or sintered semiconducting material, and can include optional structural fiber for support of the semiconducting materials, as well as an optional auxiliary thermal heating source for cleaning excess particulate matter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This invention claims the benefit of U.S. Provisional Application No. 61/822,145 filed May 10, 2013. 
    
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present general inventive concept relates generally to a ceramic substrate, and more particularly, to ceramic composite substrate that, with proper construction and proper excitation, can generate uniform plasma throughout the substrate for fluid flow treatment to influence a change in its chemical, electrical or physical properties, and method for generating plasma through the substrate. 
     Air pollution controls typically involve the filtering out of particulate matter as well as gas phase chemical pollutant treatments. Common methods of particulate removal employed today include candle filters, cyclone separators, electrostatic precipitators, and membrane filters. Gas phase pollution controls include packed beds, scrubbers, absorbers, capturers, incinerators, and condensers. All of these techniques are designed to be implemented at a few hundred degrees C. or less, which is fine for most air pollution sources in operation today. However, emerging technologies and power plant methods such as the production of syngas through gasification of various feedstocks would optimally require syngas filtering at temperatures around 1000 C. None of the above techniques can accomplish this, and there is no established technology that has been implemented on a wide-scale basis that can meet this need. 
     The present general inventive concept can meet the need of both particular removal and gas phase chemical treatment, all while being self-cleaning at these temperatures. Further, unlike and superior to the known prior art, the present general inventive concept is operational at room temperature and above, including temperatures around 1000 C. A hot syngas stream filtering technique that is both effective and has long term reliability, such as the present general inventive concept, will enable emerging gasification processes to become economically competitive to traditional energy sources. 
     SUMMARY OF THE INVENTION 
     The present general inventive concept teaches plasma generation and a method for plasma generation through a ceramic substrate. The present general inventive concept provides increased air gaps within the ceramic substrate, thus allowing more plasma volume to exist within the ceramic substrate, particularly when a fibrous ceramic filter is utilized. The present general inventive concept can provide, inter alia, the concepts and methods to remove particulate matter, deconstruct volatile organic compounds (VOC), and more generally to generate reactive species for material processing, and fluid flow modification. It should be noted that, throughout the application, any reference to fluid modification or fluid stream uses the term “fluid” to represent the general “fluid dynamics” field of science, which includes both liquid and gas phase. 
     In some exemplary embodiments, the ceramic substrate is fibrous. In other exemplary embodiments, sintered materials may be utilized. The present general inventive concept, in some of its embodiments, can include at least one semiconducting fiber for generating plasma within a plasma reactor. In some embodiments, at least one structural fiber is also included to serve as a structural support to the at least one semiconducting fiber. Some embodiments can include a composite of semiconducting fibers. In some embodiments, a dielectric material can be used in lieu of the semiconducting fiber. In some embodiments, a composite of dielectric materials can be used in lieu of the semiconducting fiber. 
     It is important to note the distinction between the known art and the present inventive concept relative to the use of dielectric materials and semiconducting fibers. The present general inventive concept is, in exemplary embodiments, composed of semiconducting ceramic fibers with dielectric fibers interwound with structural support fibers, and is an improvement upon traditional “packed bed” type apparatus. This combination of fibers in the present general inventive concept allows for plasma generation without the use of metal electrodes as well as cleansing of the contaminant gas influx through reactive plasma chemistry. 
     Some embodiments can include a composite of structural fibers. In some exemplary embodiments, a composite of both semiconducting fibers and structural fibers are included within the composite substrate. 
     In some exemplary embodiments, the sintered material includes dielectric semiconducting pellets. In such embodiments, the pellets can be fused together. 
     In the above and similar embodiments, the composite provides increased air gaps within the composite substrate, thus allowing more plasma volume to exist within the composite substrate, particularly when a fibrous ceramic filter is utilized. The present general inventive concept can provide, inter alia, the concepts and methods to remove particulate matter, deconstruct volatile organic compounds (VOC), and more generally to generate reactive species for material processing, and fluid flow modification. 
     The present general inventive concept can generate sufficient plasma volume so as to create a plasma “filter” of substantial thickness which further enhances the efficiency of the plasma treatment process. In some exemplary embodiments, the plasma filter created by the present general inventive concept can be a thickness of 1 millimeter. The present general inventive concept provides sufficient structural integrity within the ceramic structure to support a plasma filter from 1 millimeter thick up to 1 meter thick. This enhanced plasma volume provides more robust filtration than is currently available in the known prior art, both with respect to increased surface area exposure and optimal quality outcome. 
     In processes of removing particulate matter, should the particulate load become so dense as to inhibit the plasma&#39;s ability to clean, an optional auxiliary thermal heating source could be included in the overall present general inventive concept. This auxiliary thermal heating source could be configured to remove the excess particulate matter and then stand down, thus allowing the plasma to resume particulate removal. The optional auxiliary thermal heating source could function periodically, as-needed, or on command. The auxiliary thermal heating source could be utilized during system operation or, alternatively, during a system stand down for maintenance and cleaning purposes. 
     In some embodiments of the present general inventive concept, ceramic binder material may be required in the fibrous substrate. The ceramic binder material is, in essence, the glue that holds the structural fibers (fibrous substrate) together; without the ceramic binder material, the fibrous substrate could fall apart. This ceramic binder material could be, for example, mullite, alumina, silicon dioxide, or silicon carbide. The amount of binder material can range from between 50% to 150%—by weight or mass, not volume—with the exact percentage depending on the amount of additional mechanical strength one desires to add to the fibrous substrate. 
     In embodiments of the present general inventive concept where a dielectric material is present, it should be noted that these dielectric materials can include, as some examples, ferroelectric or paraelectric materials. In exemplary embodiments, impedance matching of the plasma generating substrate to the power supply enhances the proper transfer of power, thus optimizing the quality of the overall process. In addition, and optimally, a high dielectric constant provides uniformity; dielectric constants greater than five are considered high and, thus, optimal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A wide variety of potential embodiments will become more clearly understood from the following detailed description of certain exemplary embodiments, read together with the accompanying drawings in which: 
         FIG. 1  is a diagram illustrating a simplified drawing of a traditional packed-bed plasma reactor in cross-section from an axial view; 
         FIG. 2  is a diagram illustrating a simplified drawing of a traditional packed-bed plasma reactor in cross-section from a terminal view; 
         FIG. 3  is a diagram illustrating an example embodiment of the present general inventive concept, showing a ceramic composite fibrous substrate, including semiconducting fibers, within a plasma reactor; 
         FIG. 4  is a diagram illustrating an example embodiment of the present general inventive concept, showing a ceramic composite fibrous substrate, including semiconducting fibers and nonconducting structural support fibers, within a plasma reactor; 
         FIG. 5  is a diagram illustrating an example embodiment of the present general inventive concept, showing a ceramic composite fibrous substrate in a generally linear shape; 
         FIG. 6  is a diagram illustrating an example embodiment of the present general inventive concept, showing a ceramic composite fibrous substrate in a generally cylindrical shape. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description may recite various descriptive terms such as horizontal, vertical, top, bottom, upward, downward, left, right, etc., when referring to the exemplary figures, but the present general inventive concept is not limited to any such terms or physical orientations. Such terms are used for convenience of description only, and could be reversed, modified, or interchanged without departing from the broader scope and spirit of the present general inventive concept. 
       FIG. 1  illustrates a simplified drawing of a traditional packed-bed plasma reactor in cross-section from an axial view. Pellets  110  are placed in reasonably close proximity to each other, with air gaps  140  interspersed throughout. 
       FIG. 2  illustrates a simplified drawing of a traditional packed-bed plasma reactor in cross-section from a terminal view and enlarged to show detail. Pellets  110  are placed in reasonably close proximity to each other and gaps  140  are extant between pellets  110 . Gas is directed per the directional arrows through the pellets  110 . Pellets  110  can be composed of a conductive core and a dielectric outer layer, a solid dielectric material, or, alternatively, a homogeneous semi-conductive material. The electric field generated by the power supply  120  and electrode  130  induces electric potential differences between the pellets  110 . With the appropriate pellet size, excitation, and material properties, plasma  180  can be generated in the air gaps  140  between the pellets  110 . 
       FIG. 3  illustrates an exemplary embodiment of the present general inventive concept, enlarged to show detail, which includes at least one semiconductive fiber  210  between a first electrode  220  and a second electrode  230 . As established and known in the art, the first electrode  220  is connected to a ground  240  and the second electrode  230  is connected to a high voltage source  250 . Alternatively, and also known in the art, in some embodiments, first electrode  220  and second electrode  230  can be connected to separate high voltage sources of opposing polarity (not shown). Air gaps  140  reside throughout, between the semiconductive fiber  210 . Upon inducing connectivity, known in the art, between first electrode  220  and second electrode  230 , so as to create activated plasma  180 , and upon introducing gas flow  260  through the semiconductive fiber  210  and composite substrate, filtration can result. 
       FIG. 4  illustrates an exemplary embodiment of the present general inventive concept, enlarged to show detail, which includes at least one semiconductive fiber  210  and at least one structural fiber  350  between a first electrode  220  and a second electrode  230 . As established and known in the art, the first electrode  220  is connected to a ground  240  and the second electrode  230  is connected to a high voltage source  250 . Alternatively, and also known in the art, in some embodiments, first electrode  220  and second electrode  230  can be connected to separate high voltage sources of opposing polarity (not shown). Air gaps  140  reside throughout, between the semiconductive fiber  210  and structural fiber  350 . Upon inducing connectivity, known in the art, between first electrode  220  and second electrode  230 , so as to create activated plasma  180 , and upon introducing gas flow  260  through the semiconductive fiber  210  and composite substrate, filtration can result. 
       FIG. 5  illustrates the present general inventive concept in one exemplary configuration, namely, a generally planar, panel composite substrate. 
     One unique feature provided by the present general inventive concept is the diverse configurations available due to the structural support fibers in certain exemplary embodiments.  FIG. 6  illustrates the present general inventive concept in one exemplary configuration, namely, a generally cylindrical composite substrate. 
     In some exemplary embodiments, the at least one semiconductive fiber  210  is further defined to be a multitude of semiconductive fibers  210  to increase the number of air gaps  140  throughout the composite substrate, thus increasing plasma volume extant within the substrate to provide for enhanced filtration by the composite substrate. In some exemplary embodiments, an additional fiber—a structural fiber  350  (see FIG.  4 )—is included within the present general inventive concept. The structural fiber  350  provides support to the semiconductive fiber  210 . In some exemplary embodiments, this structural fiber  350  is further defined to connect between the first electrode  220  and the second electrode  230 , to provide support both to the semiconductive fiber  210  and the entire composite substrate. In some exemplary embodiments, the at least one semiconductive fiber  210  may be particles. In some embodiments, the at least one semiconductive fiber  210  may be pellets. In some embodiments, the at least one semiconductive fiber  210  may be porous matter. 
     One exemplary embodiment of the present general inventive concept is herein described that references  FIG. 4 . Note as in previous descriptions that the area between first electrode  220  and second electrode  230  has been illustrated as if zoomed in with a microscope. For reference purposes, the typical width of structural fiber  350  is on the order of microns. High voltage source  250  can be an RF high voltage power source (including impedance matching elements) operating at 13.56 MHz and 10 kV. Second electrode  230  can be a conductive layer applied to the ceramic filter media which could be composed of a high temperature electrically conducting epoxy or graphite-based adhesive applied directly to the ceramic media, therefore coming into direct contact with the at least one semiconductive fiber  210 . The spacing between the semiconductive fiber  210  is dependent on the exact characteristics of the fiber. One example of semiconductive fiber  210  is silicon carbide fiber. Silicon carbide fiber has sufficient conducting properties to couple and transmit the high voltage, high frequency power signal through the media to the first electrode  220 . Between the semiconductive fiber  210  and in any air gaps  140 , a plasma  180  can be generated with the correct application of impedance matching and power signal. In some exemplary embodiments, the media can be structurally enhanced by adding an optional structural fiber  350 , such as alumina fibers. These structural fibers can be held together with an optional binder material such as silicon dioxide (not shown). This example, when activated can clean the structural fiber  350  through oxidation of particulate matter, and treat the incoming gas flow  260  through reactive plasma chemistry. 
     Still other embodiments will become readily apparent to those skilled in this art from reading the above-cited detailed description in view of all the drawings. It is noted that the simplified diagrams do not illustrate all the various connections and assemblies of the various components, however, those skilled in the art will understand how to implement such connections and assemblies, based on the illustrated components, figures, and descriptions provided herein. 
     While the present general inventive concept has been illustrated by description of some embodiments, and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept. 
     It is also noted that numerous variations, modifications, and additional embodiments are possible, and, accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the present general inventive concept. For example, regardless of the content of any portion of this application, unless clearly specified to the contrary, there is no requirement for the inclusion in any claim herein or of any application claiming priority hereto of any particular described or illustrated activity or element, any particular sequence of such activities, or any particular interrelationship of such elements. Moreover, any activity can be repeated, any activity can be performed by multiple entities, and/or any element can be duplicated. Accordingly, while the present general inventive concept has been illustrated by description of several embodiments, it is not the intention of the applicant to restrict or in any way limit the scope of the inventive concept to such descriptions and illustrations. Instead, the descriptions, drawings, and claims herein are to be regarded as illustrative in nature, and not as restrictive, and additional embodiments will readily appear to those skilled in the art upon reading the above description and drawings.