Metallurgical furnace with scrap metal preheater and dispenser

Metallurgical apparatus – Geographic or structural installation

Reexamination Certificate

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Details

C266S200000, C266S900000, C266S901000

Reexamination Certificate

active

06696013

ABSTRACT:

BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates to an explicitly by oxygen combusted fossil fuel powered, primary energy highly efficient and ecologically friendly, gas-tight, low noise, metallurgical apparatus and closed circuit process system of single structure equipment assembly for semi-continuous, batch melting of adequate size cold metallic charge, preferably recycled steel scrap, DRI, HBI and other iron containing materials by utilizing only oxy-fuel thermal energy generated by special oxy-fuel burners, after integral and gradual high temperature, low oxidation preheating of the cold metallic charge using primarily sensible and chemical thermal energy of the flue gases, augmented by special stationary oxy-fuel burners.
II. Description of the Prior Art
Iron and steelmaking production processes relate to the most energy intensive of all production processes in the industry. Moreover, metallurgical processes of iron and steelmaking are leading also in high emissions of air polluting toxic gases and production of solid hazardous wastes. Therefore, in addition to the efforts for overall lowering of energy consumption and improvement of energy efficiency, ecological considerations are becoming necessity for protection of the environment. In many cases this has been achieved by substituting one type of fuel or energy with another. However, it is obvious, that the first priority to reduce energy consumption of the majority of metallurgical processes is the highest possible utilization of the unused process system energy losses, such as sensible and chemical heat of waste exhaust gases. By returning part of this energy, by the most direct route possible, into the metallurgical process, which produced the waste exhaust gases, initial energy requirements will be reduced, resulting in overall higher energy efficiency of the process.
First and paramountly important subject of the prior art description is the subject of the type of energy used for steelmaking from cold ferrous charge mixture.
Currently, melting of the recycled steel scrap is performed predominantly in electric arc furnaces, which have, because of their relatively high commercial efficiency, flexibility of operation, smaller size and functional simplicity replaced reverberatory open hearth furnaces. Yet, in addition to the inherited overall low primary energy efficiency, electric arc furnaces are characterized also by high energy loses via exhaust off-gases. Consequently, efforts to utilize waste energy contained in the off-gases, in as possible direct way, lead to designs which incorporate energy recuperating devices for scrap preheating into current electric arc furnace structure. These electric arc furnace aggregates, of complicated design, are reaching only some of expected performance results. Moreover, they have high initial and installation costs, malfunction of mechanisms, extensive maintenance and operating safety problems, culminating in dangerous explosions. Currently, several electric arc furnaces combined with commercially available scrap preheating equipments are unacceptably polluting the atmosphere by producing large quantities of NO
x
which, are in certain ratios with VOC (Volatile Organic Compounds) and in the presence of sunlight forming ozone.
Not to long ago, overall thermal efficiency of the metallurgical processes and their ecological impact were not always considered important or deciding factors when the choice of the process was made. Reason for that could be found in the fact, that the cost of energies was low and that the negative ecological impacts of certain processes has not been fully understood.
However, during the last decade, the cost of energy has soared and increasing ecological damages originating from metallurgical processes became obvious and evident. It became apparent that without reduction of primary energy consumption and improvement of overall thermal efficiency of metallurgical processes, steelmaking from scrap only would not be able to exist economically. This is especially true since thermal efficiency of electric arc furnace steelmaking from scrap, when considering primary energy equivalents is in the range of only 22-25%, which is comparable to the Blast Furnace/BOF combination metallurgical process.
Besides economical problems due to the cost of electric energy and eventually its availability, low primary energy efficiency and ecological pollution problems are nova days dictating compulsory and radical improvement of metallurgical process of steelmaking from scrap. Current successful improvement of the overall performance of the process of the electric arc furnace steelmaking from scrap, by adding up to 50% of supplementing thermal energy via oxy-fuel burners to the thermal energy from electric arc, are clearly and undeniably pointing in the direction of possible fundamental change of the source of energy for steelmaking from scrap, by utilizing by oxygen combusted fossil fuels, in particular switching from electric energy to natural gas as the main source of thermal energy.
Summarized, substantial primary energy savings, resulting from replacement of deficient electric energy with efficient natural gas energy for metallurgical purposes, beneficially complimented with drastic pollution reduction, possible productivity increase and improvement of safety of operation, is indicating beyond any reasonable doubt that the electric arc furnace steelmaking from scrap—being current and prior state of the art representative—is outliving its purpose and can not compete with a non-electric metallurgical apparatus and process system, processing-melting solid ferrous charge mix, using as main thermal energy source natural gas, combusted predominantly with oxygen only and having integrated preheating of the semi-continuously charged cold recycled steel scrap or other ferrous materials.
Second, equally important subject matter of the prior art description is the application of the physical phenomena of heat transfer and the mechanism of the preheater equipment.
OBJECT OF THE INVENTION
An object of the present invention is to provide a primary energy highly efficient, ecologically friendly and pollution reducing, gas tight metallurgical apparatus and closed circuit process system of simple and compact design, for semi-continuous converting-melting of ferrous charge mix into liquefied-molten steel of adequate temperature for further processing e.g. secondary metallurgy Ladle EAF or BOF, by utilizing as only prime heat source, predominantly by oxygen combusted fossil fuel, preferably natural gas, via multitude of special, retractable oxy-fuel burners—oxygen lances, after integrated, controlled, gradual and sequential, simultaneous and highest temperature assuring reduced oxidation preheating of cold metallic charge, utilizing primarily thermal energy contained in the melting process off-gases and augmented by combustion of all combustible substances being introduced with the ferrous charge mix and variable output and stationary fuel-oxygen variable ratio oxy-fuel burners, all of the gases exhausted unidirectionally with the gravitationally descending-dropping ferrous charge mix, which makes it altogether possible to overcome the plurality of aforementioned and common disadvantages and drawbacks of known, prior and current state of the art, cold metallic charge melting devices, primarily electric arc furnaces.
Another object of the present invention is to provide a self standing autonomous metallurgical apparatus of compact and rugged design with mechanism groups functionally complimenting each other and assuring ease maintenance access to all mechanism with enhanced safety of operation with the emphasis on the safety of personnel.
Another object of the present invention is to provide more than one level of dual function, sealed pairs of air and/or water cooled heat resisting, eccentrically rotating cylindrical half-drums/hoppers, creating at least two (2) independent chambers of the metallurgical apparatus and process system and also serving for holding o

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