Metallurgical apparatus – Process
Patent
1988-06-27
1990-06-05
Kastler, S.
Metallurgical apparatus
Process
266281, B22D 4100
Patent
active
049307550
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for heating ceramic material primarily in conjunction with the use of such material in metallurgical processes.
The invention also relates to an arrangement for carrying out the method.
Because of the high temperatures that occur in metallurgical processes, particularly in steel manufacturing processes, matters that concern the refractory brick and linings employed play an important role in the efficiency and economy of the process, both from an economical and practical aspect. The choice of brick material used is the result of a compromise made between, inter alia, such parameters as high temperature erosion properties, insulating properties, temperature shock stability, the cost of raw materials, and manufacturing costs. The brick is subjected to particularly high stresses when coming suddenly into contact with molten steel. The resultant rapid change in the temperature of the brick surfaces results in the occurrence of superficial cracks and so-called spalling. Naturally, these phenomena negatively affect the long-term durability of the brick.
Although these problems can be alleviated by pre-heating the bricks, the temperature achieved when using known brick heating techniques, normally affected with the aid of oil or gas burners or electrical heating devices, seldom exceed about 1000.degree. C. All of these techniques employ some form of indirect heating method, which in itself results in a pronounced temperature gradient in the brick surfaces during the course of pre-heating the brick. Because the known techniques employ indirect heating methods, these techniques have a low degree of efficiency and have hitherto resulted in a cost of from 10 to 20 Swedish Crowns for each ton of steel produced.
In addition to the aforesaid drawback relating to temperature shock, the fact that present day pre-heating techniques when put into practice seldom result in temperatures above 1000.degree. C. introduces a further drawback, namely the drop in temperature to which the molten steel is subjected, this drop in temperature being the result of an increase in the temperature of, inter alia, the brick, the refractory lining. This drop in the temperature of the steel may reach to several tens of degrees of centigrade and must be compensated for by heating the molten steel bath to corresponding over-temperatures, which entails both time and energy costs and results in wear and tear on the furnace brickwork. This drop in temperature may also, in practice, cause difficulties in the form of freezing, so-called pocketing.
The need of heating the brick in steel manufacturing processes is particularly comprehensive, and includes all vessels and transport devices that are used between the steel furnace and the pouring station.
The present invention affords a solution to the above-mentioned problems, in which the ceramic or refractory material, the brick, is heated directly.
The invention thus relates to a method for primarily pre-heat heating ceramic material in primarily metallurgical use, this material, in the form of bricks or corresponding elements, forming part of a lining or the like and being intended to be brought into contact with molten metal, such as molten steel or a corresponding melt, either directly or indirectly, said heating being primarily intended to reduce the magnitude of the temperature changes that take place in the material as a result of the alternating presence and absence of molten metal, or like molten material that has an affect on the ceramic material.
The method is particularly characterized in that heating of the ceramic material is effected with the aid of so-called microwaves, the microwave cavity required herefor being formed by an existing metallic shell or casing, preferably a steel casing, together with requisite auxiliary casing devices, such as lid devices around said material, at least one microwave generator being connected to said cavity in a substantially known manner.
The invention also relates to an arrangement for heating ceramic material, p
REFERENCES:
patent: 4324602 (1982-04-01), Davis et al.
Ekerot Sven
Svennebrink Jan
Ekerot Sven
Kastler S.
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