Heating – Tumbler-type rotary - drum furnace
Patent
1998-05-26
1999-12-14
Leung, Philip H.
Heating
Tumbler-type rotary - drum furnace
432104, 110246, F27B 700
Patent
active
060009365
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a rotating oven with a horizontal or inclined drum, of which at least the internal side is composed of a fireproof material and which is pivotably mounted around its longitudinal axis.
It concerns here an oven which is suited for a direct type of heating, such as for example obtained when burning gasses are introduced in the drum, as well as for an indirect type of heating, i.e. when the heat supplience takes place via a heating room which surrounds the drum, or by electrical resistances or by hot gases which are produced in a combustion.
It concerns here more specifically an oven, which is preferably suited for chemical treatments that are performed in a continuous way, at a high temperature and under strictly controlled circumstances, for example a strongly reducing atmosphere.
In case of a direct heating, i.e. when it concerns ovens for which the for the process required calories are generated in situ or are delivered by hot gases circulating inside the drum, these are mostly formed by a drum which is manufactured according to the technique of the immuring of a metal ferrule.
It should however be remarked, that this direct heating is seldom adapted to a chemical process which should take place under strictly controlled circumstances and in particular strongly reducing circumstances, since the means which are applied for the delivering of the necessary calories in general interfere with the chemical reactions which take place therein.
For this type of chemical process, it is thus in most cases required that the calories are supplied by means which are outside these chemical reactions, which involves a heating oven of the indirect type. In general this can be obtained with an oven of which the drum is rotated within an electrical or a by means of combustion gases heated muffle.
Since the ceramic materials are in general bad heat conductors and show strongly differing expansions with respect to the metal ferrule, the immuring technique however involves some risks, because of the fact that the very high temperature to which the metal ferrule will be subjected, will cause a decrease or a loss of the sealing of the cementing work formed by the immuring technique, which will lead more or less rapid to a corrosion of the metal ferrule.
The present invention has the essential goal of remedying this important disadvantage by providing an original concept of a rotating oven with large dimensions, which is manufactured of a ceramic material, which allows a direct as well as an indirect heating at high temperature, with a very good efficiency, and which allows to avoid problems that could appear with respect to the sealing and the heat transfer throughout the wall of the drum of the oven.
To this end, said drum comprises a tubular element of a fireproof material, which is composed of a succession of each other supporting coaxial rings, which element is brought under an axial stress starting from its both extremities in such a way that a self supporting prestressed entity is obtained.
Preferably, said cilindrical element is stressed by means of pulling rods that are uniformly distributed over the cilindrical external side of this element.
According to a preferred embodiment of the invention, due to intervention of compressed springs, said pulling rods work axially to circular supporting means which are mounted on the external side of the tubular element, which means latch in longitudinal direction of the tubular element to the extrimities of the latter.
Other details and advantages of the invention will appear from the following description of a preferred embodiment of the invention, and this with reference to the enclosed drawings, which are given as a non-limitative example.
FIG. 1 is a schematical view of a longitudinal section through this embodiment of the rotating oven according to the invention.
FIG. 2 is a section along line II--II of FIG. 1 wherein some parts have been omitted for the sake of clarity.
FIG. 3 is a section along line III--III of FIG. 1.
FIG. 4 is also a section
Leung Philip H.
Lu Jiping
Whitesel J. Warren
Zinchem-Benelux
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