GB264825A - An improved method of and apparatus for heating the charge in rotary furnaces - Google Patents

Abstract

264,825. Bojner, G., Pehrson, A. P., and Pehrson, A. H. Jan. 20, 1926, [Convention date]. Rotary furnaces.-In a rotary furnace the charge is heated by air or gas, which is passed through heating-tubes 2 rotating with the furnace, and then through or in contact with the charge, the air &c. being returned to the heating-tube for recirculation. In the construction shown in Fig. 1, in which the heated gas is delivered above the surface of the charge, the heater tubes 2 are arranged round the charge containing chamber 1. A fan 5 fitted in the end casing 6, and driven from a pulley 6<1> around the feed tube 8, draws gas from the furnace chamber through the passage 7 and returns it to the furnace through the heater tubes 2 and the pipe 10. In a modification Fig. 3, gas is supplied through the pipe 13 to a part-annular fixed channel 12 having ports 12<1> arranged to register with the tubes in the upper part of the furnace. The gas passes through these tube to an annular heater 18 rotating with the furnace, and thence through the tubes in the lower part of the furnace to the part-annular heater 14, which delivers the gas to channels 15 opening into the charge in the heating-chamber. The gas is exhausted through ther part-annular space 16 and pipe 17, and after it has been cooled in a heat exchange, apparatus, and treated for the recovery of condensible products, is returned for re-use. In another modification the channels through which the gas is supplied to the charge act as the heater tubes, and in a further form the gas is circulated by a fan 5 as in Fig. 1 and is delivered into the charge from beneath. The passage of air into the final delivery conduits within the furnace may be controlled by valves which are automatically opened when the corresponding conduit is in position beneath the charge. In the construction shown in Fig. 9 the stem 29 of the valve 30 formed as a quick-thread screw and carries a spring-controlled bell-crank lever 31 which is operated at the desired position by a stationary abutment in its path of rotation. The tubes 2 are retained in position by clamping- screws 27, and communicate with the end headers through openings 26.