Patent GB-1046977-A (GB)
Title: Improvements in or relating to a method and plant for the production of fired clay products
IPC: B28B11/24
Filed: 1962-09-01
Abstract: 1,046,977. Drying clay products. PRENTON BRICK & TILE CO. Ltd., and A. G. SHARPLES. Sept. 2, 1963 [Sept. 1, 1962 (2)], Nos. 33638/62 and 33639/62. Heading F4G. Clay products e.g. building blocks are manufactured from clay which has been steamheated prior to extrusion or moulding to shape and preliminarily heated to drive off the steam prior to firing. The preliminary heating may be for a period at or near the temperature of steam-heated extrusion and may be effected in a tunnel provided with heating flames or jets of which some at least may act directly on the clay. Further drying tunnels may be provided into which the clay after the preliminary heating passes and through which a flow of hot air or gases is passed to carry away the moisture or steam driven out of the clay. The clay product may be taken through a first drying tunnel, along a part of which flame or jet heating devices are located, to a second drying tunnel, thence through a third drying tunnel and into a tunnel kiln for firing, hot air or gases from the kiln providing heat for the drying tunnels. The movement of the clay products through the tunnels may be continuous or intermittent, with countercurrent flow of the hot air or gases. A ribbon of steam-heated clay is extruded, cut into appropriate lengths at extruding station 13 to form hollow clay blocks and carried by chain conveyer 23 to the first drying tunnel 14 in which they are given a preliminary drying by hot gases flowing countercurrently. Towards the end of the first drying tunnel the blocks are also subjected to heating by gas or oil flames from the jets 22. The blocks are then carried to second dryer 12 along conveyer 24 and further dried by a countercurrent flow of hot gases. The blocks are discharged and drawn in trucks into third drying tunnel 11 the ends of which are provided with doors, then conveyed transversely into alignment with tunnel kiln 10 and pushed into it periodically by hydraulic rams, each carriage pushing its predecessor forward and discharging a carriage from the kiln. The clay products have a long dwell time in the kiln, which may be heated by gas or oil burners or a combination of both. A large diameter duct extends from product discharge end 10a of the tunnel kiln to the final drying tunnel 11 so that hot air or gases from the kiln are discharged into ducts or flues 15, 16, 17, 18 which carry the hot gases to the remote end of the tunnel where they are discharged into the lower port as at 19 to flow up through the clay product countercurrent to the direction of movement thereof through the tunnel. A hot air inlet slot is also provided in the roof of drying tunnel 11 as indicated at 20. A duct also extends from the product intake end 11a of the third drying tunnel to end 12a of second drying tunnel 12 so that the hot gases flow countercurrently to the clay products moving therethrough, and ultimately pass into first drying tunnel 14 countercurrent to the products. One or more circulating or extractor fans 21, spaced along the length of the dryer, may be provided to ensure appropriate movement of the hot gases through the tunnels, and the flow of gases is controlled by dampers 25.