Chemistry of hydrocarbon compounds – Production of hydrocarbon mixture from refuse or vegetation – From synthetic resin or rubber
Reexamination Certificate
1999-03-19
2001-02-06
Yildirim, Bekir L. (Department: 1764)
Chemistry of hydrocarbon compounds
Production of hydrocarbon mixture from refuse or vegetation
From synthetic resin or rubber
C201S002500, C201S025000
Reexamination Certificate
active
06184427
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention deals with the treatment of various hydrocarbons and other polymers such as plastics which currently are disposed of in landfills and other waste disposal facilities in order to convert such materials to relatively clean burning sources of energy. Hydrocarbons such as bunker and sludge oils, polyesters, polyethylenes, polypropylenes and styrenes can be processed by subjecting them to hydrocarbon cracking through the use of microwaves using sensitizers in order to lower their molecular weights and, consequently, convert them to convenient liquid and gas sources of energy which are more easily and cleanly transported and burned.
BACKGROUND OF THE INVENTION
The vast majority of mixed plastics generated by consumers are disposed of in landfills, despite the fact that breakdown of these materials by natural degradation is an extremely long process. The idea of recycling mixed plastics using current technologies is not economically attractive. In addition, challenges of impurities and cross-contamination among the resin types are formidable.
It is possible to incinerate mixed plastics to recover energy. However, it has not been possible to do so in a controlled manner that reduces off-gas pollution to desirable standards. In order to discourage the practice, some regulators in Europe have elected to stipulate that energy from plastic fuel is non-renewable although energy from other waste and biomass fuel is considered renewable.
It is the goal of the present invention to provide a technology that economically converts mixed plastic into a liquid or gaseous low molecular weight fuel without generation of significant air pollution. In performing this invention, users would experience a reduction in landfill burdens together with a new clean burning fuel source and, potentially, valuable chemical co-products at commercial purity levels.
Plastics and municipal solid waste are major obstacles to eventual restoration of contaminated land. The practice of selecting for recycle only a few component types and removing only the most accessible portion reduces prospects for a solution. It is an object of this invention to provide low bulk temperature processing of waste plastics and similar hydrocarbons which is devoid of the generation of toxic off-gases which heretofore has belied an economic solution. It is a further notion that by employing technology of the present invention, waste plastics can be processed at small scale at electric power generators dispersed within various communities. In other words, this technology can be employed for manufacturing oxygenated, low-sulphur fuels to be used in electric power generation from municipal plastic waste. The present invention employs a novel cascade of thermal and non-thermal mechanisms to break down large molecules and to separate sulphur, nitrogen, halogen and metal contaminants. Proprietary catalysts and sensitizers accelerate the reactions. This process is preferably conducted in the absence of elemental oxygen or in a starved oxygen atmosphere (i.e., less than 2%) so that oxygenated pollutants are not emitted. Avoiding incineration and the high temperatures associated with pyrolysis allows high selectivity and formation of favored liquid hydrocarbons with simple removal of some contaminants before combustion to generate process heat and subsequent electric power. By-product solids, carbon and inorganic compounds and catalysts produced by the inventive process are not hazardous and in the main can be reprocessed as renewed sensitizers.
CITATION OF PRIOR ART
The prior art has described pyrolytic and catalytic cracking processes of various high molecular weight hydrocarbon materials at high temperatures and in inert atmospheres with and without using microwave irradiation.
In U.S. Pat. No. 5,470,384 issued Nov. 28, 1995, Cha et al. disclose a two step thermal process for co-recycling scrap tires and waste with emphasis on the production of light oil, gas and carbonaceous material. A first stage includes the digestion of the mixture of tires and oils in an inclined screw reactor at 600-875° F. (315-468° C.). A second stage includes thermal treatment in a horizontal reactor at 800-900° F. (426-482° C.). Addition of CaO improved the quality and value of the product by decreasing its aromatic carbon, sulphur and oxygen content and specific gravity.
In U.S. Pat. No. 4,983,278, issued Jan. 8, 1991, Cha et al. describes a process for obtaining light oil by pyrolysis of oil shale, scrap tires, waste oil and tar sands using a horizontal and inclined screw pyrolysis reactor and inclined fluid bed combustor. The maximum oil yield was found with a pyrolysis temperature 752° F. (400° C.).
In U.S. Pat. No. 5,464,503, issued Nov. 7, 1995, Avetisian et al. teach that there are unreacted components after the conversion of tires and waste oil into light oil by pyrolysis. The disclosure teaches that a screw pyrolysis reactor may be used for carrying out their tire liquefying process in order to convert unreacted hydrocarbon components to a liquid. In this process an oil/metal mixture is heated by a pyrolysis reactor to a temperature 900-1500° F. (480-815° C.) sufficient to convert unreacted hydrocarbon components to a liquid and gas.
In U.S. Pat. No. 4,347,120 issued Aug. 31, 1982, Anderson et al. disclose the process of the upgrading heavy hydrocarbons by cracking with hydrogen donor diluent. However, it is necessary to operate at temperatures of 1300-1500° C. in order to reduce sulphur levels so the product can be used as fuel.
In U.S. Pat. No. 4,329,221, issued May 11, 1982, Parcasiu et al. teach a process for reducing metal, nitrogen and sulphur content of petroleum residual oils using hydrogen-donor solvent with a catalyst. Manganese nodules which were heated to 800° F. (426° C.) were used for the catalytic desulfurization, demetalation and denitrogenation of hydrocarbon feedstocks.
In U.S. Pat. No. 5,602,186 issued Feb. 11, 1997, Myers et al. describes a process for desulfurization of rubber by mixing tire crumb with molten alkali metal before or during the devulcanization reaction. The reaction which includes the formation of alkali sulphide is extremely exothermic and must be performed in an autoclave.
All of the prior art cited above used pyrolysis processes for the conversion of polymers to light hydrocarbons at temperatures not lower than 752° F. (400° C.). They describe pyrolytical processes which require high bulk temperature, relatively expensive equipment and/or highly corrosive and explosive materials like alkali metals. In order to overcome the deficiencies of the above mentioned prior art, microwave irradiation may be employed for the catalytic conversion of high molecular weight organic materials in order to produce light hydrocarbon molecules.
In U.S. Pat. No. 4,505,787 issued Mar. 19, 1985, Fuller and Lewis teach that microwave energy can be used to produce a carbide by reaction between carbon and calcium oxide at elevated temperatures. Carbon is used to conduct heat under microwave irradiation to other reactants. It can be combined with the Hall-Heroult process to produce aluminum and carbon dioxide.
In U.S. Pat. No. 5,451,302 issued Sep. 19, 1995, Cha discloses a process using microwave energy to catalyze chemical reactions in a liquid phase, which includes the concentration of phosphoric acid by removal of bound water and the release of carbon dioxide from solutions of monoethanolamine.
In U.S. Pat. No. 4,118,282 issued Oct. 3, 1978, Wallaces discloses the process and apparatus for destructive distillation of high molecular weight organic materials by using multiple wave energy sources including microwave and ultrasonic radiation and laser beams in the presence of elemental carbon or other microwave absorptive particles including aluminum silicate or metal. However, it was necessary to include an additional electrolysis unit in this process in order to remove “soot” and unreacted carbon from the products.
In U.S. Pat. No. 4,545,879 issued Oct. 8, 1985, Wan et al. teach that microw
Honeycutt Travis W.
Klepfer James S.
Sharivker Viktor
Tairova Gulshen
Invitri, Inc.
Wittenberg Malcolm B.
Yildirim Bekir L.
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