Fluent material handling – with receiver or receiver coacting mea – With material treatment – Heating or cooling
Reexamination Certificate
2004-02-11
2004-11-16
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
With material treatment
Heating or cooling
C141S067000, C219S121370, C219S121380, C588S253000, C110S252000, C110S242000
Reexamination Certificate
active
06817388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and a system for the disposal of waste and/or hazardous materials waste.
2. Description of the Prior Art
A major problem facing modern society is the disposal of toxic waste and/or hazardous materials in a manner which minimizes harmful effects on the environment. Such a disposal system is one which is capable of reducing such toxic and/or hazardous waste to compounds which are suitable for environmental disposal. Such suitability is, of course, defined in terms of acceptable levels of pollution, and is determined by a variety of regulatory agencies.
Traditionally, hazardous waste disposal has taken the form of direct burial in landfills, or simple thermal processing of the waste, followed by burial of the solid residue, and release to the atmosphere of the volatile residue. None of these approaches have proven acceptable, due to the fact that the materials which are released to the environment tend to remain as unacceptable sources of pollution.
Another normal approach for a system for the disposal of waste and/or hazardous materials is to apply a single heat source into a confined space in an apparatus on the assumption that the temperature within the reactor vessel of the processing system will be uniform. This assumption is without knowledge of potential cold spots which can develop within the reactor vessel of the processing system. Such systems normally gasify all of the input waste constituents; however, they do not guarantee that all such gaseous elements are subjected to the total temperature environment which is necessary to ensure total and effective destruction of the more hazardous of the waste and/or hazardous materials. A single heat source which is provided at the center of the reactor vessel processing system can create paths close to the refractory wall of the reactor vessel of the processing system whereby gaseous elements can traverse without being subjected to the required temperature/residence time combination for complete breakdown. Also, the generation of gaseous elements within the reactor vessel from the gasification process can very dramatically alter the gas flow pattern within the reactor vessel. This can result in gaseous hazardous compounds being exhausted from the reactor vessel and/or not fully processed waste constituents being transferred to slag. Downstream combustion does not achieve the full temperature capability of certain processing systems, i.e., plasma processing systems. Therefore, hazardous gaseous compounds being exhausted from the reactor vessel of the processing system result in abnormal complexity through gas handling and potentially excessive pollutants being exhausted to the atmosphere. Not fully processed waste in slag can result in some or all of this hazardous material remaining in the slag after the slag is extracted from the reactor vessel. This may mean that the slag exceeds leachate toxicity limits and, thereby, remains as a hazardous waste requiring continued special disposal or storage requirements.
Other processing systems for the disposal waste and/or hazardous materials attempt to overcome these shortcomings by dramatically increasing the overall reactor vessel temperature using plasma arc generators, thus ensuring that the minimum temperature encountered throughout the reactor vessel processing chamber is sufficient for adequate thermal decomposition of all waste constituents. This approach solves the problem of insufficient exposure of some waste constituents to the high temperature which is necessary to achieve good thermal decomposition. However, in so doing, it also creates other problems, including increased plasma generator electrode erosion, decreased reactor vessel refractory life, increased heat losses, increased electricity consumption, increased cooling load for the gas handling system and increased volatilization of pollutant elements, particularly heavy metals. The resultant higher temperature product gas on exit is not only wasteful of plasma arc generator power, but is also very conducive to increased hazardous pollutants. Such problems aggregate dramatically to reduce overall system processing efficiency and cost effectiveness.
A number of approaches have thus been developed for disposing of industrial waste products. The patent literature is replete with alleged such solutions.
U.S. Pat. No. 3,766,866, issued Oct. 23, 1973 to Krum, taught a thermal waste converter with primary and secondary chambers for the pyrolysis and combustion of waste material. Thus, this patent provided apparatus for the recycling of waste material having a pyrolyzing chamber for the gasification of waste material including an inlet for the waste and an outlet for the gas produced therefrom. An independent secondary chamber had an inlet for gas from the pyrolyzing chamber and an outlet for gases of combustion. Means connected the outlet of the pyrolyzing chamber to the inlet of the secondary chamber. Means directed solid residues from the pyrolyzing chamber to the secondary chamber. A burner in the secondary chamber burned combustible gas which is produced in the pyrolyzing chamber to reduce the solid residue in the secondary chamber to a molten condition.
U.S. Pat. No. 4,438,706, issued Mar. 27, 1984 to Boday, provided an attempt to destroy waste material using direct current (DC) arc discharge type plasma torches. This patent taught the use of DC arc discharge plasma torch in combination with an oxidizing agent for the thermochemical decomposition of certain types of waste material. The torch gas was air, and the waste material in vapor form was introduced along with oxygen downstream of the plasma arc generator, where it was heated by the torch gas. The method included transferring plasma into a plasma torch at one end of a plasma reactor. The method included introducing organic waste vapor and preheated oxygen into the torch for interaction with the plasma. The method finally included discharging end products of the interaction from the end of the plasma reactor, opposite to the location of the torch, into gas washing equipment.
Faldt, et al, U.S. Pat. No. 4,479,443, issued Oct. 30, 1984, disclosed the use of an arc discharge plasma torch thermally to decompose waste material. Waste material in the form of solid particles were introduced downstream of the arc to avoid fouling of the torch as a result of particle adherence. Oxidizing agents, e.g., oxygen and air, were mixed with the waste either before, during or after the waste was heated by the torch gas. Sufficient oxidizing agents were required for the complete oxidation of the waste material. The apparatus included a plasma generator for producing a high temperature plasma in which all molecules of the plasma reach at least a desired minimum temperature. The apparatus included means for feeding hazardous waste to and through the plasma generator. The apparatus included means for feeding sufficient oxidizing agents to the hazardous waste to permit the complete decomposition of the hazardous waste to stable products. The apparatus included means for controlling the temperature of the plasma and the flow of hazardous waste through the plasma generator so that the hazardous waste can reach a sufficiently high temperature for a sufficient period of time thermally to decompose completely to stable final products.
Barton, et al, U.S. Pat. No. 6,644,877, issued Oct. 30, 1984, disclosed the use of a DC arc plasma burner for the pyrolytic decomposition of waste. Provisions were made for feeding waste material downstream of the arc electrodes to prevent interference with the formation or generation of the plasma arc. A reaction chamber following the burner was used to combine gas and particulate matter, which is quenched and neutralized with an alkaline spray. A mechanical scrubber was used to separate gases, which are withdrawn using an exhaust fan. The apparatus included a plasma burner having a temperature in excess of 5,000° C. The apparatus included a reaction vessel connected to the
Campbell Kenneth C.
Carter George W.
Feasby D. Michael
Shen Jesse Z.
Tsangaris Andreas V.
Douglas Steven O.
RCL Plasma, Inc.
Vigil Thomas R.
Welsh & Katz Ltd.
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