Heating – With work cooling structure – Combustion feed air cools exiting work by contact
Reexamination Certificate
1999-10-14
2001-11-06
Lu, Jiping (Department: 3749)
Heating
With work cooling structure
Combustion feed air cools exiting work by contact
C110S281000
Reexamination Certificate
active
06312253
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cooler for cooling particulate material which has been subjected to heat treatment in an industrial kiln, such as a rotary kiln for manufacturing cement clinker, which cooler comprises an inlet, an outlet, end walls, side walls, a bottom and a ceiling, at least one stationary supporting surface for receiving and supporting the material to be cooled, means for injecting cooling gas into the material, as well as a reciprocating scraper system which comprises a number of rows of scraper elements which extend transversely across the direction of movement of the material, said elements being moved back and forth in the direction of movement of the material in order to convey the material forward over the supporting surface.
In EP 0718578 a cooler of the aforementioned kind is described. In this known cooler, the scraper elements are made up of cross bars with a triangular cross-sectional profile, with the bars being mutually connected via chains and being moved back and forth on the supporting surface by means of chain wheels fitted at the ends of the supporting surface. This known cooler has several drawbacks. Because of the high temperatures which occur in the cooler, and particularly at the inlet end of the cooler, as well as the substantial forces which are required to convey the material through the cooler, the chains must be designed with relatively large dimensions. As a result, the chains will form so-called shadow areas of equivalent size, i.e. areas in which the chains obstruct the upward-flowing cooling gas so that the overlying material is not cooled as intended. Also, the cross bars in the known cooler are not firmly fixed to restrain them from moving, neither perpendicularly to the material's direction of movement nor in terms of rotation about their own longitudinal axis. In cases where a larger body of material is to be conveyed through the cooler, one or several cross bars may therefore be forced vertically upwards, and may come to ride on the body. This will reduce the conveyance of material through the cooler. In cases where a cross bar is lifted at one side only, the cross bar will also be able to move towards one side of the cooler, thereby giving rise to operational disorders. Rotation of one or several of the cross bars may have an adverse effect on the efficiency of conveyance. Furthermore, the known cooler is vulnerable to operational disorders, for example in event of rupture of a single chain link, given the necessity to shut down the cooler in order to undertake the necessary repair work. A further disadvantage of the known cooler is that the driving system in the form of the chains consists of wear parts which must be replaced at regular intervals.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a cooler by means of which the aforementioned disadvantages are eliminated.
This is achieved by means of a cooler of the kind mentioned in the introduction, and being characterized in that each row of the transverse scraper elements is firmly fixed to at least one drive plate oriented in the direction of movement of the material, and in that said drive plate extends at least across the entire length of the supporting surface, and in that said drive plate is led either through the supporting surface, the ceiling, one of the side walls and/or at least one of the end walls of the cooler, where the drive plate is connected to a drive arrangement for movement back and forth.
Hereby is obtained a better and more uniform cooling of the material in the cooler, a better and safer conveyance of the material through the cooler, a higher degree of operational reliability and a reduction of the wear to which the drive elements are exposed. The cooling of the material is improved due to the fact that the drive system can be designed with smaller dimensions, thereby reducing the attendant shadow area. Among other things, this is ascribable to the fact that the drive plate, because it extends across the entire length of the supporting surface, will always be moving along its own track, which means that it shall never push away material being deposited in front of it. Also, as is the case for the known chain option, there will not be accumulated a chain force throughout the cooler. The conveyance of material through the cooler is improved due to the scraper elements being firmly fixed to the drive plate. As a result, the scraper elements will neither be able to move perpendicularly relative to the material's direction of movement nor will they be rotatable about their own centre axis. The cooler attains a higher degree of operational reliability in that, essentially, only the scraper elements proper are exposed to wear. Should a single scraper element break, cooler operation may be continued without any appreciable problems until next shutdown for maintenance is scheduled to take place. The drive plate is only subjected to minimum wear due to the fact that, as previously noted, it moves back and forth along its own track.
As previously mentioned, the drive plate may either be led through the supporting surface of the cooler, its ceiling, one of its side walls and/or at least one of its end walls. In cases where the drive plate is led through the supporting surface, it is preferred that the drive plate is substantially vertical, and that at all times over a part of its length, equivalent to the length of the supporting surface, it extends at least down into a slot which is provided throughout the length of the supporting surface, and, furthermore, that over at least parts of its length it extends down through the slot to an underlying chamber in which the drive plate is connected to a drive arrangement for movement back and forth.
In order to protect the drive plate and to shield the supporting surface against drop-through of material, the cooler may be designed so that at both sides of the drive plate it comprises a wall element which is fixed to the supporting surface, with said wall elements extending over the entire length of the supporting surface and protruding slightly less into the cooler than the drive plate, and so that on the upper side of the drive plate and over its entire length a plate element is fitted which is designed so that it extends over and beyond the upper side edge of the wall elements. Hence the drive plate and the slot in which the latter is guided is effectively shielded against the material in the cooler, thereby minimizing the wear on the drive plate and effectively restraining the material from gaining access to the slot in the supporting surface. In such an embodiment it is only the plate element fitted on the drive plate which moves back and forth in the material, and it is doing so along its own track, so the wear on said plate is insignificant.
To minimize the torsional forces which the drive plate must be able to absorb, and thus to reduce the necessary dimensions of the drive plate, it is preferred that each row of transverse scraper elements is fixed to at least two substantially parallel drive plates.
The drive arrangement, which supports and drives the drive plate or plates in the compartment under the supporting surface, may comprise a drive frame which is preferably made up of two longitudinal girders and at least two transverse girders. The transverse girders may be designed as stiffening braces to enhance the rigidity of the drive frame. In the preferred embodiment where each row of transverse scraper elements is fixed to two drive plates, the drive plates are fixed to the longitudinal girders. Each of the longitudinal girders of the drive frame is movably supported at least at two locations by means of rails fixed to the underside of the longitudinal girders, said rails sliding in bearings, preferably linear roller or ball bearings, which are fixed to the machine frame at an appropriate distance. It is preferred that the drive frame is supported by two bearings for each longitudinal girder. In principle, the drive frame may be driven b
Fons Mogens Juhl
Schomburg Flemming
Baker & Botts L.L.P.
Lu Jiping
Smidth & Co. A/S
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