VERTICAL RETORTS AND CHAMBER O VENS 177
each bed. The temperature of the retort is thus adjustable, enabling top or bottom heating to be obtained as desired. A stream of air is cir-culated round the casting at the base of the retort, tlius cooling the coke and providing heated secondary air.
Tongued and grooved bricks are used for building up the retorts, whicb. are rectangular in section, taping from 21 indies by 4 feet 9 inches at the bottom to 15 inches by 3 feet 4 inches at the top.
Coal bogies holding one ton of coal Tunning on a narrow-gauge track are filled at the ground-level direct from railway wagons, storage bunkers or coal dumps, and by means of a hoist, electrically or steam operated, they are raised to the charging floor. These bogies are fifrted with. a grid, on which any large lumps of coal are broken.
The main gas offtake from the retort is placed at the top, and forms part of the casting connecting the coal hopper to the retort. The gas passes under a deflector plate, provided to prevent the coal enter-ing the gasway, and th.en.ce by means of an 8-inch pipe to the collecting main at the side of the sefrting. A screw-down disk valve is provided to enable the retort to be isolated when necessary.
An auxiliary or relief ofltake is also provided in the end wall of the retort, which is used to relieve the pressure when starting up and if swelling coals or coal contaming a high percentage of dust are used.
The collecting main is provided with a seal curtain plate and clean-
Fig. 95.—Coal-Feedino Chambbk and Gas OfI’TAKE. HOLMBS-WlNSTANLEY SYSTEM.
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