Abstract:
The present invention is a vitrification and gasification system that operates at elevated pressures. The system includes a processing chamber having numerous penetrations, and seals for effectively sealing the penetrations to the processing chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a divisional application of U.S. application Ser. No. 12/787,222, filed May 25, 2010, which claims priority to U.S. Provisional Application No. 61/181,099 filed May 26, 2009, the applications of which are herein incorporated by reference, in their entirety, for any purpose. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates to gasification and waste treatment systems. More specifically, this invention relates to high temperature systems used to convert organic matter to useful fuels such as synthesis gas. 
       BACKGROUND OF THE INVENTION 
       [0003]    There have been a number of examples of apparatus and methods for converting organic matter into useful fuel. For example, U.S. Pat. No. 5,666,891 title “Arc Plasma-Melter Electro Conversion System for Waste Treatment and Resource Recovery” describes a system that combines joule heating and plasma heating in a process chamber. In this system, organic materials can be converted into hydrogen rich gasses which may be used as fuels, or which may be converted into other fuels, such as liquid methanol. 
         [0004]    The advantages of these systems are readily apparent, as they allow waste products, which normally must be disposed of at some expense, to be converted into fuels, which can then be sold. In this manner, these types of systems convert a cost into revenue source. 
         [0005]    As a result, significant research and development related to improving these waste treatment systems is ongoing. Generally speaking, this research attempts to make these systems more efficient and less expensive. The present invention accomplishes both of those goals simultaneously. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is an improvement over prior art gasification and vitrification systems that provides numerous advantages over those prior art systems. The main distinguishing feature of the present invention and these prior art systems is that the present invention operates at elevated pressures. The present invention is thus distinguished from the prior art by the use of higher pressures, and the ancillary systems used to contain those pressures. Operation of gasification and vitrification systems at elevated pressures provides numerous advantages over operating at lower pressures, but it presents problems which were heretofore not encountered in the prior art. The present invention provides those advantages, while overcoming those problems. 
         [0007]    As an example of the advantages offered by operating at elevated pressures, the gas produced by gasification and vitrification systems typically contains impurities such as inorganic particulate, carbon particles, soot, tars and oils. These impurities are typically handled with additional processing steps. For example, additional reactions of the organic impurities in a high temperature thermal residence chamber can cause these impurities to be converted into gasses, such as CO and H.sub.2. By operating at elevated pressures, the present invention reduces the chamber volume that is required to provide the necessary residence time for these reactions to occur, resulting in greater throughput, and thus more efficient operation of the overall system. As a further result, the size of the thermal residence chamber may be reduced, resulting in a cost savings. As yet another further result, the energy necessary to promote these reactions is reduced, resulting in yet another cost savings. 
         [0008]    Operations at elevated pressures has the same effect on the other equipment used to scrub impurities from gasification and vitrification systems. Generally, this scrubbing equipment may be sized smaller, able to be operated at higher rates of throughput and with less energy required, thereby resulting in lower capital and operating costs. 
         [0009]    Operating gasification and vitrification systems at elevated pressures also presents numerous complications not encountered by the prior art systems. Specifically, operation at elevated pressures requires that all penetrations of the processing chamber have modifications that contain that pressure. For example, many of the gasification and vitrification systems use graphite electrodes to introduce energy into a processing chamber. Seals may be formed between these electrodes and the processing chamber to prevent gasses from escaping from within the processing chamber to the atmosphere surrounding the processing chamber. For example, U.S. Pat. No. 6,018,542 shows one prior art method of forming a seal between the electrode and the processing chamber to prevent the escape of gasses. In this system, the seal also forms an electrode feeder device for allowing a continuous feed of the electrodes while keeping the atmosphere at the exterior of the chamber separate from the atmosphere in the interior of the chamber. This prior art electrode feeding device is shown in the cut away view of  FIG. 1 . 
         [0010]    As shown in  FIG. 1 , the electrode feeding device includes a mounting flange  1  attached to a cooling and electrical contact assembly housing  2 . The mounting flange  1  is constructed to allow the electrode feeding device to be attached about a penetration in a process chamber through which electrodes  3  are introduced. Isolating collar  4  is provided interior to electrical contact assembly housing  2  which holds in place electrical contact collar  5 . Isolating collar  4  also prevents power from electrical contact collar  5  from being passed to electrical contact assembly housing  2 . 
         [0011]    Power and cooling water are provided to electrical contact collar  5  through power and cooling water port  6  which is in communication with electrical contact collar  5  via hose  7  and a wire connection (not shown). A secondary gas purge port  8  is provided to allow the introduction of an inert gas, preferably nitrogen, into the electrode feeding device to flush air from the electrode feeding device. Electrode  3  is inserted through electrical contact collar  5 , which passes electrical power to the electrode  3 . Cooling water from power and cooling water port  6  prevents overheating of electrical contact collar  5  allowing continuous, high powered operation. 
         [0012]    The inner  9  and outer  10  internal sealing mechanisms are each assembled of two flexible bladders  11 . Bladders  11  surround electrode  3  and are fitted over insulating bladder supports  12 . Passage of gas through bladder inlet  13  allows the bladders to be inflated and deflated. When inflated, bladders  11  tighten around electrode  3  forming an airtight seal. When deflated, bladders  11  loosen from electrode  3  allowing the electrode  3  to slide through the bladder  11 . Within the inner  9  and outer  10  internal sealing mechanisms, isolating bladder supports  12  are separated from one and another and bladder assembly flanges  14  by isolators  15 . The inner  9  and outer  10  internal sealing mechanisms are each held together by screws  16  threaded through the bladder assembly flanges  14 . Bladder assembly flanges  14  also connect electrical contact assembly housing  2  with electrode housing  17 . Electrode housing  17  is divided by bellows  18  which allows the inner  9  and outer  10  internal sealing mechanisms to move independently of one and another. 
         [0013]    While the prior art electrode feeding device described in  FIG. 1  is effective at keeping gasses from passing out of the processing chamber when the system is operated at ambient pressures, operation at elevated pressures creates problems unknown in the prior art. For example, the inventors have discovered that when the system is operated at higher pressures, the graphite electrodes are sufficiently porous to allow gasses within the processing chamber to escape through the electrodes themselves. Thus, even though a seal, such as an electrode feeding device, may be used to form a gastight seal between the electrode and the processing chamber, gasses inside the processing chamber are nevertheless forced out of the processing chamber through the electrode itself 
         [0014]    Accordingly, one aspect of the present invention is to prevent the escape of gasses through the electrode. This is accomplished by providing a coating to the graphite electrodes in addition to the sealing mechanisms, such as the electrode feeding device, of the prior art, thereby preventing the pressure from within the processing chamber from forcing gasses through the electrodes into the surrounding atmosphere. Suitable coatings include, but are not limited to, acrylic, cyanoacrylate, epoxy, urethane, poly(methyl methacrylate), and hot melt adhesives. 
         [0015]    These coatings may be applied to the electrode with a simple application to the surface of the electrode. Additionally, a vacuum may be applied to the coated electrode to cause these coatings to diffuse into the electrode. Generally, it is preferred that the coating material be sufficiently diffused within the electrode to form an airtight coating on the outer surface, but no so diffused through the electrode as to interfere with the electrode&#39;s ability to conduct electricity. 
         [0016]    In addition to sealing the electrodes themselves, the present invention provides a method for sealing all of the penetrations into the processing chamber to prevent the escape of gasses, organic materials, vitreous glass, and metals, all of which are contained within the processing chamber during processing. Accordingly, the present invention contemplates both the operation at elevated pressures, and the various techniques described herein for effectively sealing the penetrations to the processing chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The following detailed description of the embodiments of the invention will be more readily understood when taken in conjunction with the following drawing, wherein: 
           [0018]      FIG. 1  is an illustration of a prior art system for maintaining the internal atmosphere of a gasification system as separate from the atmosphere external to the system. 
           [0019]      FIG. 2  is an illustration of one embodiment of the present invention. 
           [0020]      FIG. 3  is an illustration of a second embodiment of the present invention. 
           [0021]      FIG. 4  is an illustration of the arrangement of the joule heating electrodes in one embodiment of the present invention. 
           [0022]      FIG. 5  is an illustration of a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0023]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitations of the inventive scope is thereby intended, as the scope of this invention should be evaluated with reference to the claims appended hereto. Alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0024]    As shown in  FIG. 2 , one embodiment of the present invention is a processing chamber  101  for converting organic material  102  to useful gas products  103 . The processing chamber has at least one port  104 , and at least one electrode  105  penetrating the processing chamber  101  through the port  104 . Organic material  102  and oxygen are introduced into the processing chamber  101 , while maintaining the processing chamber  101  at a pressure of at least 2 atmospheres. Electrical energy is provided to the electrode  105  to induce reactions between the organic material and the oxygen to form synthesis gas  103 . As a result of maintaining a pressure of at least 2 atmospheres, the present invention also provides a seal  106  to prevent pressure from inside the processing chamber  101  from expelling organic material  102 , oxygen or synthesis gas  103  from the processing chamber  101  through port  104 . Seal  106  is preferably provided as described previously, with the combination of electrodes coated with sealing materials  122  and a sealing mechanism between the processing chamber and the electrode, such as an electrode feeding device. 
         [0025]    Another embodiment of the present invention further provides a method for converting organic compounds to useful gas products and the gas products manufacturing system shown in  FIG. 3 . The method begins by providing a processing chamber  101  having a set of joule heating ports  109  and a set of plasma heating ports  108  as shown in  FIG. 3 . A set of joule heating electrodes  111  is provided, with each of the joule heating electrodes  111  penetrating the processing chamber  101  through each of the joule heating ports  109 . A set of plasma heating electrodes  110  is provided, with each of the plasma heating electrodes  110  penetrating the processing chamber  101  through each of the plasma heating ports  108 . Organic material and oxygen is introduced into the processing chamber  101  while maintaining the processing chamber  101  at a pressure of at least 2 atmospheres. Electrical energy is provided to the joule heating electrodes  111  sufficient to form and maintain a molten glass bath  121  within the processing chamber  101 . Electrical energy is provided to the plasma heating electrodes  110  sufficient to form a plasma  112  and to induce reactions between the organic material  103  and the oxygen exposed to the plasma  112  to form synthesis gas. A seal  106  is provided to prevent pressure from inside the processing chamber  101  from expelling organic material, oxygen or synthesis gas from the processing chamber  101  through the ports. 
         [0026]    Another embodiment of the present invention may further include a material port  113 , an inlet gas port  114 , a glass drain port  115 , a product gas port  116 . Oxygen is introduced to the processing chamber  101  through the inlet gas port  113 . Material port  113  has an opening to the outside, where material is introduced to the system, and an opening to the processing chamber  101 , where material is fed into the processing chamber. The two openings form an airlock which is operated to prevent pressure from inside the processing chamber  101  from expelling organic material, oxygen and/or synthesis gas from the processing chamber  101  through the material port  113 . Gas from within the material port  113  is preferably purged into the processing chamber  101 . Seals are provided to prevent pressure from inside the processing chamber  101  from expelling organic material, oxygen or synthesis gas from the processing chamber  101  through the ports. An encapsulation  117  is provided surrounding the product gas port  116  to maintain pressure within the processing chamber  101 . The synthesis gas is removed through the product gas port  116  and is preferably routed to a thermal residence chamber  119 . Other gas treatment equipment that is conventional and known in the art (not shown) can also be incorporated. Preferably, the output of the thermal residence chamber  119  is provided to other gas treatment equipment for further treatment. An encapsulation  118  surrounding the glass port  115  is provided to control the pressure differential on each side of the glass port  115 . Glass from the molten glass bath is removed through the glass port  115 . 
         [0027]    Alternatively, the method for converting organic compounds to useful gas products and the gas products manufacturing system may further include a separate gasification system, such as a downdraft gasifier. While the separate gasification system may require an energy source to begin operations, it is preferred that the separate gasification system operates as a result of exothermic reactions between the organic materials fed into the gasifier and oxygen, for example from air, and the separate gasification system therefore does not have a need for an ongoing, external source of power during normal operations. As shown in  FIG. 5 , the separate gasification system  120  is interposed between the material port  113  and the processing chamber  101 . 
         [0028]      FIG. 4  shows a detailed cut away view of one embodiment of the seal for the joule heated electrodes. As shown in  FIG. 4 , joule heating electrode  111  projects from pressure tank  201  into processing chamber  101 . Water cooling jacket  202  surrounds joule heating electrode  111 . Power is provided to joule heating electrode  111  through electrical connection  203 . Cooling water is provided to joule heating electrode  111  through water supply  204 . Connection flange  205  forms a pressure tight fitting around electrical connection  203 , water supply  204 , and gas supply  212  sufficient to prevent pressure from within pressure tank  201  from escaping. 
         [0029]    AC holder flange  206  holds electrode  111  in place. On either side of AC holder flange  206  are electrical isolators  207 . Housing flanges  208  are on the opposite side of electrical isolators  207 . Bolt  209  is secured by nuts  210  and then holds the assembly of AC holder flange  206 , electrical isolators  207  and housing flanges  208  in place. Refractory blocks  211  provide thermal isolation between pressure tank  201  and processing chamber  101 . 
         [0030]    It is preferred that the pressure in the pressure tank  201  be maintained as equal to, or even slightly greater than, the pressure in the processing chamber  101 . Gas supply is used to provide gas, preferably nitrogen, to pressure tank  201  to maintain that pressure. Line  213  provides communication of the pressure within pressure tank  201  and processing chamber  101 . Pressure control valve  214  provides relief to pressure tank by allowing a flow of nitrogen from pressure tank  201  to processing chamber  101 . 
         [0031]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. Only certain embodiments have been shown and described, and all changes, equivalents, and modifications that come within the spirit of the invention described herein are desired to be protected. Any experiments, experimental examples, or experimental results provided herein are intended to be illustrative of the present invention and should not be considered limiting or restrictive with regard to the invention scope. Further, any theory, mechanism of operation, proof, or finding stated herein is meant to further enhance understanding of the present invention and is not intended to limit the present invention in any way to such theory, mechanism of operation, proof, or finding. 
         [0032]    Thus, the specifics of this description and the attached drawings should not be interpreted to limit the scope of this invention to the specifics thereof. Rather, the scope of this invention should be evaluated with reference to the claims appended hereto. In reading the claims it is intended that when words such as “a”, “an”, “at least one”, and “at least a portion” are used there is no intention to limit the claims to only one item unless specifically stated to the contrary in the claims. Further, when the language “at least a portion” and/or “a portion” is used, the claims may include a portion and/or the entire items unless specifically stated to the contrary. Likewise, where the term “input” or “output” is used in connection with an electric device or fluid processing unit, it should be understood to comprehend singular or plural and one or more signal channels or fluid lines as appropriate in the context. Finally, all publications, patents, and patent applications cited in this specification are herein incorporated by reference to the extent not inconsistent with the present disclosure as if each were specifically and individually indicated to be incorporated by reference and set forth in its entirety herein.