Industrial electric heating furnaces – Environmental control – Arc furnace
Reexamination Certificate
2000-04-17
2001-01-09
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Environmental control
Arc furnace
C373S008000, C373S018000
Reexamination Certificate
active
06173002
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of using an electric arc gasifier to process waste. A plasmatic primary fluid heated by an electric arc mixes with injected waste to crack and gasify the components of the mixture. The instant method provides a high waste destructive rate with a low cost process, which can be aimed to produce chemical or gaseous products and recover high value metals.
2. Description of the Related Art
There are a number of methods developed to process waste in various forms, and with a variable degree of efficiency as the economics of most processes do not account for a high degree of destruction of the waste, i.e. low cost processes creates a liability from an environmental point of view. On the other hand, processes that do have high destruction rates also have very expensive operating costs. Our invention overcomes these problems to combine low operating and capital costs with high destruction efficiency.
Common methods include the use of electrodes to implement the use of high temperatures in a furnace for destroying waste (Queiser et al). Also, known in the art are methods and apparatuses for disintegrating or incinerating waste using arc-forming electrodes. Electric arcs abruptly raise temperatures of compounds from the heat of alternative fluids to form a high temperature plasma. In particular, as can be seen in U.S. Pat. No. 5,811,752 by Titus et al., a molten pool provides a conducting path for at least two arc forming electrodes capable of providing and maintaining joule heating to convert waste dissolved in a liquid pool to stable products. Operating conditions of this process are dependent, however, on the desired liquid pool medium used for chemical modification of the waste. Gaseous or liquid compounds, and even solids with high volatile content may bypass the destruction medium as they fall into the port of melted down ceramic metal, thereby producing secondary waste.
As can be demonstrated by U.S. patent application Ser. No. 09/152,636, an electric arc-activated, non-catalytic burner can produce synthetic gas by mixing an injection with an ignited primary fluid under high temperature and high pressure to produce gases used for combustion or other industrial processes. A new method of use can be demonstrated to account for waste processing of products that have variable chemistry.
As an example, electric arc furnaces are used for the production of steel, and the material charged to these furnaces is usually steel scrap and eventually direct reduced iron. The production of steel by this method generates a significant amount of dust that is collected in a baghouse or similar equipment in the fumes purification system. The disposal of EAF dust is costly because of the presence of heavy metals in its chemistry. The present method is particularly suitable for the treatment and recycling of the components of this dust, as well as other costly and inefficiently recoverable wastes, such as chlorinated hydrocarbons.
Chlorinated hydrocarbons are a waste produced by some chemical processes. The disposal of this waste is costly and the recovery is inefficient. The electric arc gasifier can process these chlorinated hydrocarbons, recover hydrochloric acid, and produce synthetic gas (CO, H
2
, or carbon dust and H
2
) in a very efficient manner.
The bulk of chlorinated hydrocarbons is processed in incinerators (rotary kilns). The thermal efficiency of the incinerators is low. The capital cost is in the same order of the electric arc gasifier process or higher, but the operating cost is higher due to low efficiency and consumable cost. In addition, environmental permitting is difficult because of formation of dioxins and NOx. The emissions also increase the liability associated to the operation of the plant.
There is a need, then, for a more efficient method of processing waste using the electric arc method that will automatically correct operating conditions based on the complexity of waste products and variably be capable of recycling desired compounds.
PRIOR ART
U.S. Pat. No. 3,575,119, Apr. 13, 1971 (Marr, Jr.) teaches an electrical arc apparatus for disintegrating and incinerating a slurry organic material. The bonds between carbon and other atoms are dissolved as solid organic matter is continuously positioned between two arc forming electrodes.
U.S. Pat. No. 5,811,752, Sep. 22, 1998 (Titus et al.) shows a tunable waste conversion systems and apparatus. The methods and apparatus for such conversion include the use of a molten oxide pool having predetermined electrical, thermal and physical characteristics capable of maintaining optimal joule heating and glass forming properties during the conversion process.
U.S. Pat. No. 4,760,585, Jul. 26, 1988 (Queiser et al.) teaches how radioactive wastes are treated in a furnace which has electrodes for electric heating. Carbon-containing waste, possibly also carbon of a carbon bed, is reacted to form water gas (CO+H
2
), which is burned after purification in an exhaust gas plant.
U.S. Pat. No. 4,995,324, Feb. 26, 1991 (Williams) demonstrates a system for recovery of the heat value of waste material. Collected bales of waste material are passed through a bale breaker to release the waste material into a free condition so it can move in a free flowing stream into a conveyor-type storage unit for movement to a grinder.
U.S. Pat. No. 5,090,340, Feb. 25, 1992 (Burgess) shows an apparatus and method for the disintegration of waste by subjecting the waste within a closed chamber to plumes of an electrically generated high temperature plasma. One embodiment comprises a portable device capable of disintegrating waste over a large area such as at a waste dumpsite.
U.S. Pat. No. 5,566,625, Oct. 22, 1996 (Young) teaches a high temperature combustion apparatus incorporating a pneumatically suspended combustion zone and capable of supporting relatively high combustion temperatures in excess of 2400° C. (4352° F.).
U.S. Pat. No. 5,666,891, Sep. 16, 1997 (Titus et al.) demonstrates a relatively compact and highly robust waste-to-energy conversion system and apparatus. In one embodiment of the invention, the conversion system includes an arc plasma furnace directly coupled to a joule heated melter.
U.S. Pat. No. 5,798,497, Aug. 25, 1998 (Titus et al.) shows a relatively compact self-powered, tunable waste conversion system and apparatus. The preferred configuration of this embodiment of the invention utilizes two arc plasma electrodes with an elongated chamber for the molten pool such that the molten pool is capable of providing conducting paths between electrodes.
SUMMARY OF THE INVENTION
It is the objective of the present invention to process and destroy waste in powder, liquid, slurry, or gaseous form, and to process waste of variable chemistry using an electric arc gasifier that will automatically adapt to the processing of the various compounds, and will automatically correct for various operating conditions.
It is a further objective of the present invention to recombine elements produced in the destruction of the waste into useful products and gases such as HCl and H
2
, and carbon black for industrial applications.
It is a further objective of the present invention to inject a tertiary fluid to control the metallurgy of the process, and condition slag formers to suit the application, as well as to remove undesirable compounds or elements from the gas stream.
It is a further objective of the present invention to eliminate the possibility of dioxin, furane, and NOx formation during the destruction process.
It is a further objective of the present invention to use the reactor as a low cost, high power plasma torch with power levels up to 150 MW in continuous operation.
REFERENCES:
patent: 3575119 (1971-04-01), Marr, Jr.
patent: 4181504 (1980-01-01), Camacho
patent: 4760585 (1988-07-01), Queiser et al.
patent: 4995324 (1991-02-01), Williams
patent: 5090340 (1992-02-01), Burgess
patent: 5259863 (1993-11-01), Schneider et al.
patent: 5493580 (1996-02-01), Fuda
Hoang Tu Ba
Law Offices of K. Patrick McKay, PE, Esq.
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