It is generally known in the art for grate plates of the aforementioned type to be installed in various kinds of grate apparatus in which a free-flowing material, e.g. cement materials, ore materials and the like, are treated in the particular manner necessary with the aid of gases flowing upwards from the bottom through the layer of material. This treatment may for example be preheating, preburning, burning and above all cooling of the said materials.
In the as yet unpublished German Patent Application No. 196 37 904.7 a grate plate of approximately the aforementioned type is proposed which by its construction should achieve a particularly favourable and uniform flow through the material for treatment and thus an optimum heat exchange between material and treatment gas. For this purpose the document proposes that the gas flow channels be constructed like a pipe and approximately in zigzag form, and overall in the material transport direction they should extend obliquely from the lower face of the plate to the upper face of the plate.
A box-shaped grate base element with two lateral supporting flanges is also known from EP-B-0 167 658, in which the supporting flanges extend vertically and in the longitudinal direction of the plate and have attached to them in approximately ladder or dovetail form strip-shaped members which determine the surface and form between them gas slots which run through the entire width of the grate element. In each case two such ladder-shaped or fork-shaped structures consisting of lateral supporting flanges and strip members are put together in a complementary and form-locking manner in such a way that the strip members which extend parallel to one another form overall with the gas flow slots remaining between them a material support surface which is level on the top.
A grate cooler for cooling hot bulk material is disclosed in DE-A-37 34 043. In this document box-shaped grate plate supports are provided which have level upper cover plates each covered by an equally flat grate plate which is bent downwards at its front end. Slot-shaped gas flow openings are provided in the cover plate of the grate plate support and in the grate plate which is disposed flat above it, whilst slot-shaped connecting openings are formed between these two superimposed level plates as a connection between the said gas flow openings. Since the gas flow openings in the two superimposed level plates are in each case displaced with respect to one another in the longitudinal direction of the plate, solids should be prevented from falling downwards through the gas flow openings in the event of a failure of the cooling gas supply, in which case throttle components can also be disposed in this system of openings.
In the two last-mentioned grate plate constructions it has been repeatedly found that the upper faces which come into contact with the material are still relatively susceptible to wear, and this is apparent particularly when relatively strongly abrasive material, such as is the case for example with cement clinker which is to be cooled, is to be transported along on the grate apparatus or a corresponding cooler grate and thereby to be cooled with cooling gas.
The object of the invention, therefore, is to make further improvements to a grate plate in such a way that even in the case of strongly abrasive material, such as for example cement clinker or the like, the material carrier plate has a relatively long service life (high durability) and is distinguished by relatively favourable and economical manufacture.