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Electric furnaces with carbon radiator
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Electric Furnaces with Carbon Radiator.-HENRI GEORGE, of the Saint-Gobain Company, France, describes in Electrical Engineering, Vol. 54, No. I I, a type of electric furnace for application to metallurgy and to operations at very high temperatures. The essential feature of the furnace is a carbon radiator mounted within the furnace chamber and raised to a very high temperature by the current flowing through it. This radiator can be reduced to a simple graphite rod, which allows high current densities (200 to 500 amperes per square centimeter) to be used, and which radiates freely to the charge and to the walls. From the electrical viewpoint the general properties are those of a resistance furnace; there is constant load for each value of the supply voltage and absence of any inductance. From the thermal viewpoint, the use of graphite resistors makes it possible to attain very high temperatures (3000 deg. C. in special furnaces) or to build very flexible furnaces, the power rating of which may be quite considerable. Mr. George describes a small kw. furnace for melting steel in which the power consumption was 0.8 kwh. per kilogram for steel cast at 1650’ C. and 0.5 and 0.25 kwh. per kilogram for cast iron and bronze, respectively. Several interesting features are embodied in the mechanical construction of this type furnace, as well as in the electrical construction. The latter are made important by the necessity of bringing large currents to a radiator of small diameter, of eliminating eddy current losses, and also of avoiding the inductance caused by any closed loops in the feeders. It is stated that these furnaces are the simplest and least expensive among the industrial electric furnaces. Additional advantages include a definite atmosphere, the possibility of operating in a vacuum, easy regulation of carburization, facility of reduction processes and the consistency of the analysis of the metal prior to and after fusion. R. H. 0. “The chemical senses of smell and taste tell about the chemical make-up of things outside the body. Because his sense of taste is not nearly delicate enough, the research worker develops chemical and electrical means of measuring minute amounts of acidity in terms of pH values, or he uses a chemical color indicator.“-T. A. Boyd, “Research.” 181
TOPICS.
Electric Furnaces with Carbon Radiator.-HENRI GEORGE, of the Saint-Gobain Company, France, describes in Electrical Engineering, Vol. 54, No. I I, a type of electric furnace for application to metallurgy and to operations at very high temperatures. The essential feature of the furnace is a carbon radiator mounted within the furnace chamber and raised to a very high temperature by the current flowing through it. This radiator can be reduced to a simple graphite rod, which allows high current densities (200 to 500 amperes per square centimeter) to be used, and which radiates freely to the charge and to the walls. From the electrical viewpoint the general properties are those of a resistance furnace; there is constant load for each value of the supply voltage and absence of any inductance. From the thermal viewpoint, the use of graphite resistors makes it possible to attain very high temperatures (3000 deg. C. in special furnaces) or to build very flexible furnaces, the power rating of which may be quite considerable. Mr. George describes a small kw. furnace for melting steel in which the power consumption was 0.8 kwh. per kilogram for steel cast at 1650’ C. and 0.5 and 0.25 kwh. per kilogram for cast iron and bronze, respectively. Several interesting features are embodied in the mechanical construction of this type furnace, as well as in the electrical construction. The latter are made important by the necessity of bringing large currents to a radiator of small diameter, of eliminating eddy current losses, and also of avoiding the inductance caused by any closed loops in the feeders. It is stated that these furnaces are the simplest and least expensive among the industrial electric furnaces. Additional advantages include a definite atmosphere, the possibility of operating in a vacuum, easy regulation of carburization, facility of reduction processes and the consistency of the analysis of the metal prior to and after fusion. R. H. 0. “The chemical senses of smell and taste tell about the chemical make-up of things outside the body. Because his sense of taste is not nearly delicate enough, the research worker develops chemical and electrical means of measuring minute amounts of acidity in terms of pH values, or he uses a chemical color indicator.“-T. A. Boyd, “Research.” 181