Heating – Work chamber having heating means – Combustion products heat work by contact
Patent
1986-08-05
1987-08-18
Favors, Edward G.
Heating
Work chamber having heating means
Combustion products heat work by contact
34218, 266901, 432 14, 432 17, F72B 700
Patent
active
046874402
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The invention relates to an apparatus for heating charging material, in particular metal scrap, by a heating gas, in particular hot waste gas from a smelting or refining unit, comprising a charging material pre-heater in the form of a container for receiving the charging material to be heated up, which has a closable bottom opening for emptying the container, a removable cover for introducing the charging material into the container and a lower and an upper opening for introducing and removing the heating gas, wherein the interior of the container is divided by a grid which falls away in an inclined position towards the bottom opening, into a receiving space for the charging material and a free lower annular space into which the lower opening for the heating gas opens.
2. Background Art
In apparatuses of the above-indicated kind, there is the problem of preventing local overheating of the charging material which is to be heated up. When using light scrap such as steel turnings, local overheating can result in the charging material catching fire.
U.S. Pat. No. 2,805,143 discloses recycling a portion of the heating gas which has passed through the charging material preheater and cooled down in heat exchange relationship with the charging material, and mixing it with the hot gas at the intake side of the charging material preheater. That procedure reduces the temperature of the gas so that overheating of the charging material can no longer occur. However, when the temperature of the heating gas which is introduced into the charging material preheater is reduced, the heating time is increased in length, together with a reduction in the mean temperature to which the charging material in the charging material preheater can be heated.
German published specification (DE-AS) No. 23 02 012 discloses a process for preheating scrap by heating it with combustion gases in at least two heat-insulated containers, wherein the combustion gases are generated under the heating cover of the first container and are then passed through the further containers which are disposed downstream thereof; in that process, in the periodic feeding of a container, the heating gas is alternately supplied from above and from below. In the last heating stage, that is to say, before the container is passed to the smelting furnace, heating gas only ever passes therethrough in one direction so that, in relation to long flow paths, a substantial temperature difference between the heating gas intake side and discharge side is inevitable.
In the apparatus disclosed in German laid-open application (DE-OS) No. 30 38 515, the attempt is made to provide for uniform heating of all the material which is to be heated up, and a reduction in pressure drops, by virtue of the hot gases being passed through the charging material in such a way that the gases are distributed over the cross-section thereof. For that purpose, provided at the inner periphery of the charging material preheater, at uniform peripheral spacings, is a plurality of passages extending in a vertical direction, which each have orifices for communicating the passages with the interior of the preheater in a radial direction, while there is a vertical passage in the middle of the preheater. Although that arrangement provides that the intake cross-section for the hot gases may be substantially increased and it is possible to achieve short flow paths thereby reducing the danger of local overheating phenomena, that however suffers from the following difficulties. For the purposes of forming the vertical passage in the middle of the charging material preheater, a core member is fitted into the container before the charging material is introduced, which core member is removed again after the introduction of the charging material. In that case, particularly when using small scrap, pieces can fall into the vertical passage formed by the core member and partly block it off. In that case there is no longer any guarantee that the gas will flow uniformly through the chargin
REFERENCES:
patent: 3645516 (1972-02-01), Turpin et al.
patent: 3832128 (1974-08-01), Paul
patent: 4255131 (1981-03-01), Johnson, Jr.
Favors Edward G.
Kortec AG
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