Abstract: A controlled atmosphere furnace having radiant heating tubes, through which hot gases from a fuel burner are passed, is converted to electrical operation by removing the fuel burner and exhaust connections from the heating tubes and replacing these with electrical connector extensions connected to an electrical power source so that electrical current is driven longitudinally through the heating tube walls and converted therein to heat which is radiated into the furnace enclosure.

Abstract: A DC electric arc furnace melt connection of the type formed by a metal connector with an inner end melted by the melt and an outer end kept solid by cooling, extends from the furnace hearth at a declination straight and free from curvature and with a uniform and constant cross-sectional area from end to end having a rectangular oblong cross sectional shape with the long sides extending in a horizontal direction. The purpose is to reduce the flow currents normally formed by gas bubbles and electrodynamic effects within the melted portion of the connector and which cause the melted part to wipe over the unmelted part of the connector with the undesirable result of promoting heat exchange between the two parts.

Abstract: A housing including an open-cage type framework for a coreless induction furnace. The framework includes upper and lower horizontally disposed ring members. Each ring member is constructed of a non-magnetic metal except for an insulating fastener in each ring which closes the ring mechanically but prevents a continuous electrical path or loop in each ring. The upper and lower rings are joined by a plurality of vertical columns which are similarly electrically insulated from the rings. The framework thus provides a rigid structure for supporting the internal furnace components while at the same time insuring that deleterious current paths or loops in the framework are not created during operation.

Abstract: Useful heat is recovered from electric furnaces using two heat recovery systems. Primary heat recovery is effected using liquid water or other cooling liquid and is performed in such a manner that the temperature of the liquid does not exceed its boiling point at atmospheric pressure. Secondary heat recovery is effected by indirect heat exchange between the exhaust gas of the furnace and a gaseous cooling medium and is performed in such a manner that the gaseous medium is heated to a temperature above the boiling point of the cooling liquid. A part or the entirety of the cooling liquid is then heated by the gaseous medium.

Abstract: A side wall for a UHP electric arc furnace includes water cooled panels positioned within the outer shell of the furnace. The panels form water channels and have multiple fins projecting inwardly from the panel into the furnace. The panels including the fins are formed of pure copper or copper alloy which has a high heat conductivity. The fins have a thickness of at least 10 mm and they project horizontally inwardly toward the furnace for at least 70 mm. The fins are spaced vertically apart in the range of 30-80 mm. The space between the fins is filled with a castable refractory.

Abstract: This disclosure relates to an electric arc furnace control system for positionally displacing the consumable furnace electrodes. Each electrode is coupled to an electric motor and arranged for vertical height displacement in relation to the material in the furnace. An arc current control signal is derived by comparing the actual arc current with a reference electrode arc current. In addition, a reactive power control signal is also derived by comparison of the (actual reactive power/actual real power) with a desired ratio of (reactive power/real power). The arc current control and the reactive power control signals are algebraically summed to provide an output error signal which is sent to the respective electric motors to provide rectilinear displacement of the electrodes.

Abstract: Electrical apparatus and power distribution systems are protected from lightning strike currents and voltages by the addition of mutually coupled chokes, such as bifilarly wound chokes, in electrical series relationship with the apparatus and the power distribution system to increase the impedance therebetween and cause lightning currents to flow along alternate current paths.

Abstract: A radiantly heated furnace is provided with a heating arrangement capable of generating heat from two different sources of energy. The arrangement includes a thin-walled tube extending within the furnace which operates as a resistor when connected to a high current source of electrical energy to generate and radiate heat within the furnace. The thin-walled tube also acts to radiate heat into the furnace from hot burner gases injected therein by a fuel fired burner. The arrangement is so constructed that switching from the electric to the gas fire mode or vice versa can be swiftly effected without removal of electrical connections or burners.

Abstract: Load cells continuously measure the weight of a consumable electrode as it is being melted in an electroslag melting furnace. This information is compared to similar information obtained from load cells measuring the weight of a supply of granular slag and/or alloy additions intended to be added to the molten slag in the furnace. The addition of the granular slag and/or alloy is controlled based on the results of this comparison.

Abstract: The walls of a furnace are water cooled by a wall construction that comprises a pair of closely spaced, parallel plates defining a coolant flow passage. The plates are connected at their opposite ends to headers that place the passage in fluid communication therewith. According to one aspect of the invention the plates are formed as concentric annuli that encircle the furnace interior while the headers are ring headers. According to another aspect of the invention the walls are constructed of modular panels employing the inventive concept.

Abstract: A wall construction for an electric furnace. An outer metallic casing provides the shape and structure for the furnace and an insulating inner liner is formed of a plurality of compressibly stacked ceramic fiber batts. Electrically insulating hanger members are provided for supporting an electrical heater element within the furnace. The hanger members comprise ceramic spools mounted on elongated rods. A group of such rods are welded to a plate which is placed between a pair of adjacent batts. Means are provided for securing the plate in place for preventing movement of the hanger members. In an alternate form, the hanger members are formed, integrally with a mounting member, of ceramic.

Abstract: A pollution control system for an electric furnace station which provides for noise abatement and the collection and discharge of pollutant gases during charging, refining and tapping stages of electric furnace operations. A housing surrounds the electric furnace which is sized so as to enable tilting of the furnace during tapping, the housing having movable sections to enable entry of charging means for the furnace and entry of personnel, with an exhaust means in the upper region of the housing. In addition, a tapping shield is provided having a supplementary exhaust system to remove pollutant gases during tapping and additive deposition. Air curtain or other means are provided to preclude escape of pollutants during charging of the furnace through the charging means.

Abstract: A dynamic gradient furnace in which a plurality of heating zones along an axis of the furnace are controlled sequentially to provide a moving temperature gradient profile through the heating chamber of the furnace.

Abstract: A method and apparatus wherein a plasma arc column is embraced by a gas flow along its entire length, within a furnace melting chamber, for being cooled and constricted. The gas drawn off the melting chamber, cleaned and cooled, may be used for this purpose. The apparatus is provided with a closed circuit including a heat exchanger, a dust collector, a gas flow controller and a gas blower. The circuit is used for drawing off the gas from the melting furnace and supplying it into an annular space between the nozzle of the plasma generating means and the outer housing.

Abstract: A metal processing furnace of the indirect arc type having opposed electrodes projected into and establishing an ionized atmosphere in the furnace crucible is provided with apparatus that introduces a finely divided charge mixture consisting essentially of silica and coke into the system for free-fall into and through the ionized atmosphere. Following reaction of the mixture's ingredients in the ionized atmosphere, silicon carbide crystals are deposited at the bottom of the furnace interior below the ionized atmosphere for subsequent collection and removal from within the furnace system. By control of charge composition and process parameters, silicon carbide crystals having predominantly either alpha or beta crystalline structures and with crystal sizes predominantly in the range of 250 to 3,000 microns are produced.

Abstract: A high temperature electrical resistance heater for use within a high temperature furnace. The heater is composed of an elongated tubular element having first and second tubular sections contiguous with one another, the first section being of a high resistivity silicon carbide and disposable within a furnace chamber, the second section being of a low resistivity silicon carbide and disposable external to the furnace chamber. An elongated rod of silicon carbide of low resistivity is disposed coaxially within the tubular element and in electrical connection with an end of the first tubular section. The coaxial ends of the second tubular section and of the rod include contact areas for electrical connection to an external power source. The high resistivity tubular section provides efficient heating, while the low resistivity tubular section and coaxial rod provide a conductive electrical path to the heating section while minimizing the heating thereof.

Abstract: For the melt reduction in a DC electric arc furnace of iron oxide material of such a fine grain size that it can be blown about by the action of an electric arc, a hearth for the iron melt used, is provided with an outer wall and a roof down through which an arcing electrode extends with its tip positioned to form an arc with the melt, the electrode having a lengthwise passage through which the fine-grained oxide material, together with equally fine-grained particles of carbonaceous material, are fed to the tip. This prevents substantial loss of the materials by their being blown away from the arc. The arc, unshielded by the flow of materials, can produce from the space radiation damaging to furnace linings.

Abstract: A wall element for furnaces useful in all types of metallurgical furnaces but particularly in electric arc steel refining furnaces is comprised of a metallic block defining a cooling circuit in the interior thereof and a lining of refractory bricks anchored firmly to the cooled metallic block. The metallic block carries anchoring lugs projecting from the internal face of the block, each lug consisting of a foot portion and a retaining portion, which is constituted by an enlarged end of the foot portion opposite the internal face. Each refractory brick has a face adjacent the internal face of the metallic block and defining a recessed portion of a cross section matching that of a corresponding one of the anchoring lugs.

Abstract: For the melt reduction of iron oxides, arcs are formed between at least three arcing electrodes in an iron melt, the electrodes being symmetrically positioned about a common vertical axis. The arcs are powered by direct current with the electrodes being cathodic and the melt anodic, and the electrodes are interspaced so closely together that the arcs, due to the direct current powering, converge and form a common focal spot at the electrodes' axis, on the melt, the spot remaining stationary and with any slag on the melt blown away so that the spot is formed by bare metal. Iron oxide material and carbonaceous material, in fine form, is fed downwardly to this spot with the reaction between the oxides and carbon occurring practically immediately.

Abstract: The invention relates to a system for regulating the depth of immersion of melting electrodes in electrical slag remelting furnaces, consisting of an apparatus for the detection of the resistance and for changing this resistance upon the spatial displacement of the end of the electrode within the slag layer, a signal corresponding to the resistance being relayed to a regulating system for the electrode drive.