Heating – Advancing structure flexing – looping or coiling sheet – web...
Patent
1996-02-12
2000-09-12
Ferensic, Denise L.
Heating
Advancing structure flexing, looping or coiling sheet, web...
432 72, 432152, F27B 928
Patent
active
061168947
DESCRIPTION:
BRIEF SUMMARY
The present invention pertains to a continuous furnace for baking ceramic molded parts.
The term "continuous furnace" designates all types of continuously operating furnaces, i.e., e.g., tunnel furnaces with furnace carts or roll-over type heating furnaces.
These continuous furnaces are usually designed as follows (viewed in the direction of transportation of the material): Via an inlet, the material to be baked first passes through a heating area, then a baking area, and finally a cooling area before it is removed at the outlet of the furnace.
The term "ceramic molded parts" covers generally all types of ceramic molded parts, such as porcelain, sanitary ceramics, etc. However, it expressly also covers special ceramic products, such as ferrites, e.g., soft ferrites.
Such soft ferrites are characterized in that they are prepared by using a binder/pressing aid and are processed into molded parts. These additives usually comprise organic compounds, such as polyvinyl alcohol.
Compared with prior-art ceramic products, the said soft ferrites are characterized by a special behavior during the baking process. These additives burn out during the heating in the furnace, i.e., in the heating area, so that the furnace atmosphere is loaded with organic components.
Care must therefore be taken to prevent binder vapors from becoming concentrated in the furnace atmosphere in the heating area; on the contrary, uniform atmospheric conditions must always be ensured in order to guarantee a uniformly high product quality.
It was suggested in DE 2 001 148 A that for a uniform heating of the material to be baked, the air of the furnace be led from a tunnel furnace into an intermediate space, that it be fed from there into a combustion chamber, and that it be subsequently led back into the furnace at a different spot.
DE 32 32 294 C1 discloses a process for sintering soft ferrites in a batch furnace, i.e., an intermittently operating furnace, in which the furnace atmosphere is additionally heated outside the furnace chamber during the so-called "binder phase" by continuously burning the binders volatilized during the binder phase in a circulation outside the furnace chamber, and the combustion gases thus formed remain in the circulation, and only the excess amounts of gas are removed.
The gas fed into the furnace chamber shall thus be practically "inert." However, the furnace atmosphere cannot thus be controlled/regulated in the desired manner. In addition, the prior-art process is limited to an intermittently operating furnace.
The basic object of the present invention is to provide a continuous furnace possessing the following features: The components present in the smoke gas of the furnace, which are active in terms of energy, especially the binder components released in the heating area, shall be thermically utilized. Moreover, a defined furnace atmosphere shall be able to be set especially in the heating area. Finally, the pyrotechnical process shall be optimized in terms of energy.
This object is accomplished by a continuous furnace for baking ceramic molded parts having the following features: chamber, heating area, warm air ducts, which open, at spaced locations from one another, into the heating area,
Such a continuous furnace offers the following advantages: Hot air, which is loaded with, e.g., gaseous binder components released from the ceramic molded parts during their heating phase, is extracted from the heating area at one or several spots.
The combustion gases are subsequently fed into a combustion chamber and are burned there, so that an extensively purified hot air can be returned into the heating area. The combustion chamber may be arranged in the furnace, but separated from the furnace flue, e.g., under the furnace flue, or on the outside.
The hot air returned has a temperature of, e.g., 600.degree. C. to 1,000.degree. C., i.e., its temperature is markedly higher than the temperature needed in the heating area.
In addition, the temperature in the heating area differs (increases) in the heating area when viewed
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Kolln Bernd
Richter Henning
A. Earley John F.
A. Earley III John F.
Ferensic Denise L.
Lu Jiping
Riedhammer GmbH
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