Patent GB-1490404-A (GB)
Title: Process and apparatus for baking ceramic products
IPC: F27B9/26
Filed: 1975-03-25
Abstract: 1490404 Heat treatment furnaces SATRACO 25 March 1975 [25 March 1974 20 Feb 1975] 12334/75 Heading F4B [Also in Division B8] In an intermittent or batch type furnace for baking ceramic products such as hollow bricks or tiles and comprising an elongate baking enclosure 1 of rectangular cross-section charged with a plurality of stacks 5 of products supported at equally spaced intervals i on wagons 4, a fan unit 3 is provided to ensure a longitudinal flow of gases in the enclosure from one end thereof to the other, and burners 10 are located in the two lateral enclosure walls 8 to discharge a regulatable stream of heat into the spaces i between adjacent stacks 5 in a direction perpendicular to said longitudinal gas flow direction. Each lateral wall 8 is provided with a series of burners 10 disposed alternately at two different heights, the arrangement being such that each space i is supplied with a stream of heat from two burners 10 at different heights. The wagons 4 are provided with lateral vertical plates 32 which move, for sealing purposes, in slideways 33 filled with sand. A support frame 2 surrounding the enclosure 1 comprises uprights 11 disposed along the lateral walls 8, longitudinal members 12 and cross members 13 extending above the enclosure roof 7. Suspended from the cross members 13 are longitudinal bars 13a carrying hooks 13b suspending the roof 7 which comprises a refractory layer 7a surmounted by an insulating layer 7b. Opposite ends of the enclosure 1 are closed by means of inclined slidable doors 9 movable by a winch 20. The fan unit 3 comprises a fan 26 and two interconnected ducts 23 the ends of which communicate with the interior of the enclosure via openings 25 in the roof 7 adjacent the doors 9. Sets of flaps 30 and 31 are provided to respectively regulate the amount of gas recycled to the furnace and the amount allowed to escape via a stack 28, so as to maintain a constant pressure within the enclosure during baking. In use when the furnace has been fully charged with stacks 5 of products and the doors 9 closed, preheating is effected by igniting and regulating the burners 10 to give an increasing stream of heat, the heat furnished by the burners becoming constant when the baking temperature is reached. Cooling of the baked products is achieved by supplying the burners solely with air. When the ceramic products comprise hollow bricks (see Figs. 3-6), the bricks are disposed in superposed identical layers up to the desired height. In the case of flat, arcuate or Z-shaped tiles, the wagons are each provided with a pair of superstructures (48, Figs. 7-9, not shown) composed of horizontal slabs (49) and longitudinal pillars (50) to define a series of openended horizontally extending rectangular passages (51) for receiving the tiles. In an alternative embodiment (Fig. 10, not shown) each superstructure comprises a series of removable cassettes (58) composed of refractory material and having a number of projections extending inwardly to support wall tiles (60) in a horizontal position and spaced apart vertically.