Refrigeration – Liquid contacting discrete commodity
Reexamination Certificate
1999-08-04
2001-05-01
Capossela, Ronald (Department: 3744)
Refrigeration
Liquid contacting discrete commodity
C062S063000, C198S822000, C198S841000
Reexamination Certificate
active
06223552
ABSTRACT:
The invention relates to an arrangement for the controlled cooling of hot-briquetted direct-reduced sponge iron in the form of an apron conveyor located in a tank.
An arrangement for cooling is known from the German patent specification DE 29 28 501 C2. This arrangement is comprised of a quench tank and a conveyor placed therein in inclined position for transporting connected briquettes.
In the different processes for the direct reduction of iron, solid oxidic input material is reduced to iron by means of reduction gases. The pellets or lump ores formed thereby can only be stored under special protective conditions as due to the microporosity of the products an exothermal reaction with atmospheric oxygen may occur. Therefore, a hot-briquetting plant has been connected downstream of several processes in order to compact the reduced material and, thus, to reduce the risk of reoxidation due to the surface which is reduced thereby.
The briquettes formed during hot briquetting have a temperature of approx. 750° C. and are cooled to approx. 50° C. in order to prevent self-ignition. However, the energy stored in the cooled briquettes must still suffice to dry them up.
Cooling is performed in a quench tank, i.e. a tank filled with water, in which wire mesh belt conveyors or apron conveyors are located onto which the hot briquettes drop. The apron conveyors consist of perforated plates connected to one another, to which wheels running on rails are mounted by means of pins. The plates are connected to one another by fishplate bush links. The conveyors are driven by a conveyor chain connected with the wheel axles.
The fines accompanying the briquettes get onto the bottom of the tank as well as onto the rails through the holes in the plates. Combined with aggressive substances in water, with the high surface pressure acting on the supporting surfaces of the wheels at the rails and with the radial stresses occurring, primarily the wheels and pins are highly worn. As the wheels run dry in front of the point of briquette discharge, the aforementioned conditions are aggravated by the alternation of wet and dry condition.
The object of the invention is to develop a cooling system to reduce the wear of the conveyor elements and thus to increase the availability of the cooling system due to the lower maintenance expenditure. The design of the plates and of the drive is to be modified so that less fines penetrate into highly stressed areas.
The invention is characterized in that the individual plate is designed as conveyor trough, at least one sliding plate each being located on the two opposed longitudinal outsides and the conveyor troughs being movably supported on rails by means of the sliding plates and connected with at least one chain.
A novelty of this invention is that the drive and the bearing can be separated as the conveyor troughs are supported by means of sliding plates and the drive acts directly on the conveyor trough by means of at least one chain.
As the translation elements are designed as sliding plates and rails, the surface pressure is reduced to less than one hundredth compared to wheels running on rails. As a result, the wear of the translation elements is reduced. The sliding plates cover the slideways partly from the material flow so that less fines get directly onto the slideways and wear is further reduced.
Another feature of the invention is that one mounting plate each is located on the two opposed longitudinal outsides of the conveyor trough, to which mounting plate one sliding plate each is fixed on its upper and lower sides. This type of mounting of the sliding plates on the conveyor trough enables the sliding plates to be easily exchanged if they are worn.
Another feature of the invention is that, if two sliding plates are placed on each longitudinal outside and at each conveyor trough, the upper sliding plate—seen in the direction of conveying—is thinner than the lower sliding plate. This feature takes into account that the lower sliding plate is subject to higher wear due to the loading of the conveyor trough and the direct action of fine material and the upper and lower sliding plates can thus be simultaneously exchanged, which results in increased plant availability.
Another feature of the invention is that the individual conveyor trough is driven by means of at least one chain, preferably a round steel chain, a detachable connection being established between the conveyor trough and the chain. Driving by means of chains has the advantage that guidance of the conveyor troughs is ensured by prestressing the chain. The detachable connection between the conveyor trough and the chains facilitates plant maintenance.
The invention is further characterized in that the individual conveyor trough is driven by means of at least one chain, preferably a round steel chain, which is provided with plug-in pushers detachably connected with fishplates located on the bottom side of each conveyor trough. The fishplate arrangement on the bottom side of the conveyor trough has the advantage that the latter protects the chains engaging there from the direct action of sponge iron briquettes or fine material. Moreover, the use of round steel chains is advantageous as these are self-cleaning.
Another feature of the invention is that the conveyor troughs are made of brace plates, which reduces the probability of deformation of the conveyor troughs by impact on the side stop.
The feature of one side stop being placed on both sides of the conveyor troughs serves for emergency guidance of the conveyor troughs in case of a sideward motion resulting from loading the conveyor trough, on the one hand, and for protecting the tank, on the other hand, because the side stop prevents the conveyor trough from damaging the tank wall.
An essential feature of the invention is that the horizontal distance between the upper sliding plate and the side stop amounts to maximally half the average diameter of the sponge iron briquettes. This is to prevent the sponge iron briquettes from dropping between the sliding plate and side stop, from getting jammed there and locking the conveyor troughs, or from causing increased wear.
The last feature of the invention is that in the area of the slideways that is located above water level a spraying device is placed, which ensures uniform sliding conditions for the sliding plates and rinses deposits of fine material from the slideways into the tank.
REFERENCES:
patent: 1996781 (1935-04-01), Winton et al.
patent: 4087265 (1978-05-01), Benson
patent: 4582193 (1986-04-01), Larsson
patent: 5115908 (1992-05-01), Williams
patent: 621746 (1981-02-01), None
patent: 964127 (1957-05-01), None
patent: 1194319 (1965-06-01), None
patent: 0002137 (1979-05-01), None
patent: 0105954 (1984-04-01), None
patent: 1364451 (1964-10-01), None
patent: 2069442 (1981-08-01), None
patent: 2108459 (1983-05-01), None
Hoertnagl Franz
Schober Helmut
Tscherne Wolfgang
Zimmerbauer Karl-Heinz
Capossela Ronald
Ostrolenk Faber Gerb & Soffen, LLP
Voest-Alpine Industriean-lagenbau GmbH
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