GB421403A - Improvements in and relating to drying plant - Google Patents

Abstract

421,403. Rotary furnaces. HODGSON, C. G., and MILLARS' MACHINERY CO., Ltd., Pinners' Hall, Great Winchester Street, London. May 15, 1933, No. 14086. [Classes 51 (ii) and 55 (ii)] In a rotary furnace adapted for the treatment of bituminous macadam at a relatively low temperature, or of bituminous asphalt at a higher temperature, a burner and an outlet flue are provided at each end of the drum and are so controlled that during the low temperature treatment the gases flow in parallel with the materials, while during high temperature working the flow is countercurrent. As shown in Fig. 1 the burners deliver into combustion chambers 10, 18 and the charge is fed through in shoot 8 at the same end as the low temperature chamber 10. Fixed end heads 9, 13 lead to a common suction box 15 having a hinged damper 17 adapted to close the connection between the box and either head. The drum has inclined internal conveying vanes which may be set at a steeper angle at the feed end to prevent back spill of the charge. Controlled air inlets 21, 23 are provided in the two end heads to determine the quantity of dust drawn off from the drum with the waste gases, and an alternative arrangement for the same purpose comprises a casing 27, Fig. 2, between the end head 12 and the suction fan, a partition 28 forming a restricted passage 28<a>, and a damper 29 by which the cross section of the flue passage can be varied. Escape of dust to the atmosphere may be prevented by passing the gases through a washer, Fig. 6, fitted with baffle plates 31, spray pipes 32 and a sludge outlet 34. Specification 353,458, [Group XIII], is referred to.