Furnaces – Process – Incinerating refuse
Reexamination Certificate
1999-11-08
2001-06-26
Ferensic, Denise L. (Department: 3749)
Furnaces
Process
Incinerating refuse
C110S342000, C110S344000, C110S345000, C110S235000, C110S203000, C110S210000, C110S211000, C110S233000, C110S250000, C110S242000
Reexamination Certificate
active
06250236
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to multi-zone reactor systems for processing waste and, in particular, to a multi-zone reactor system for destruction, vitrification and recycling of bulk solid, liquid, and/or mixed-phase waste.
BACKGROUND OF THE INVENTION
Processing of waste and especially hazardous waste, is a continuing problem for many industries and in non-industrial settings. Landfill space is decreasing and costs are rising. Moreover, the shipment and processing of hazardous waste can pose a significant risk to public health and the environment. In view of these concerns, the public and industry have long sought waste processing solutions that reduce waste volume, detoxify hazardous content and/or neutralize or stabilize waste products to prevent undesired spreading through leaching, airborne discharge or the like.
A particularly challenging problem is the treatment and disposal of heterogeneous waste, i.e., waste materials that are highly variable in their chemical composition and physical properties. Such waste may include organics, inorganics and mineral compounds and may be in the form of solids, liquids or mixed phase materials. Heterogeneous waste is produced in many environments including households, semiconductor fabrication facilities, chemical and petrochemical industrial plants, hospitals, military bases, chemical and nuclear weapon production facilities, and fossil fuel and nuclear power plants.
Conventional waste processing reactor systems generally lack the versatility needed to effectively handle a broad range of heterogeneous waste. Such systems typically process waste in a reactor chamber that is heated by a plasma torch, or an induction or joule effect heater. Unfortunately, each of these reactor types has disadvantages for processing certain types of waste. For example, induction heaters are problematic for certain types of waste. In particular, induction heaters are suitable mostly for melting metal and their efficiency and effectiveness are greatly reduced when the waste contains other materials such as cellulose and plastic. Plasma heaters, on the other hand, do not have space requirements suited for complete reaction and polishing of effluent gases over the reactor bed in many applications. Single zone joule effect reactors are, however, problematic for processing waste streams that may contain metallic materials. Joule effect heaters employ a pair of electrodes that extend into the reactor bed to electrically heat the reactor bed as well as the waste contained in the reactor bed. Any molten metallic materials in the waste can provide a conductance path between the electrodes and short-circuit the electrical resistance that generates the joule effect heat.
Thus, most feed preparation operations require sorting and contact handling by the operators to reduce the size of objects and remove objects that are not suitable for processing by the particular heater type or configuration of the reactor system. For example, where joule effect heating is employed, the feed waste materials must be sorted to remove metallic elements, a rather time consuming and costly process. Handling of waste objects, especially in the case of biomedical, infectious, or radioactive waste, can also jeopardize the health and safety of the operator.
Another disadvantage of current reactor systems are their inability to prevent various waste batches from mixing (or co-mingling) with one another. In a typical operation, the inert components of the various waste feed batches mix with one another, accumulate in the bottom of the chamber and melt as a single homogeneous glass matrix.
Accordingly, an improved waste reactor system is, therefore, desirable.
SUMMARY OF THE INVENTION
An object of the present invention is, therefore, to provide an improved waste reactor system.
Another object of the invention is to provide such a waste reactor system and method for handling waste that employ a bulk processing chamber, adapted for in-container thermal destruction, in addition to its other processing chambers.
The present invention is directed to multi-zone reactor systems, related subsystems, and associated methods of the types described in U.S. Pat. No. 5,809,911 of Feizollahi for improved processing of heterogeneous waste. Such reactor systems are useful for processing solid, liquid, and mixed phase waste generated in a variety of environments and having correspondingly varied compositions which may include metallic materials, cellulose and plastic material, and hazardous organic components. These reactor systems have been employed to reduce waste volume, destroy hazardous organic components, stabilize toxic metals and compounds into an increasingly non-leachable solid, recover reusable products and energy, and release stable compounds to the surrounding environment.
The multi-chamber reactor of Feizollahi can be operated in oxidation or reduction modes and includes at least first and second chambers containing respective first and second reactor beds heated to temperatures of at least 2,000° F. and, more preferably to temperatures of about 2,500° F. The first and second reactor beds are heated by heaters of the same or different types. In one embodiment, the first and second reactor beds are both heated by joule effect heaters and is best suited for waste feedstocks that contain little or no metallic materials. Waste is introduced into the first chamber where it is reacted to yield a first waste by product in the first reactor bed and a first effluent outside of the first reactor bed. In the second chamber, the first effluent is reacted to yield a second reaction product in the second reactor bed and a second effluent outside of the second reactor bed. The second reactor chamber provides additional space and retention time for processing a gaseous effluent from the first reactor and allows for settlement of particulates into the second reactor bed for further reaction.
The present invention includes an additional bulk processing unit (BPU), adapted for in-container thermal destruction, that facilitates processing of large bulk material in relatively large packaging or shipping containers and reduces the safety and health risks to operators sorting or handling the waste feedstock. While still in the containers, the organic material including the hazardous contents of the waste feedstock is thermally destroyed and converted to gaseous and solid decomposition products. The gaseous decomposition products are conveyed to a vitrification reactor for conversion into safe products including CO
2
and H
2
O. The solid decomposition products such as ash and inert material that can be fed to the other reactor chambers for vitrification.
The waste feedstock containers can be safely removed from the BPU, and the contents of the containers can be subjected to metal or other sorting processes, transferred to a subsequent reactor chamber, or deposited in a storage area for later processing. The metal sorting can include screening through a sieve and/or a magnetic is separator. In the subsequent reactor chamber, the ash and inert residues are melted to form a highly leach resistant final glass product.
To avoid mixing waste batches that must not be co-mingled, the ash and inert residues generated from waste feedstocks of similar constituents, properties, or origin, are accumulated in respective storage containers. When a sufficient quantity of a particular waste residue is accumulated, the reactor chambers are drained to remove all previous molten glass, so the different types of accumulated residues can be processed separately.
The invention, therefore, facilitates removal of a maximum amount of organic material from the waste so that it is safer for the operators to handle; facilitates differentiation and maintenance of separate waste feeds to the reactor chambers whenever the waste feeds are unsafe to mix or whenever separate processing of the waste is desired for better tracking of certain waste types; eases size reduction requirements for the waste feedstock; increases
Allied Technology Group, Inc.
Ferensic Denise L.
Rinehart K. B.
Stoel Rives LLP
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