Modern Gasworks Practice

154 MODERN GASWORKS PRACTICE Cast-iron hangers are swung from a shaft above the extractor which prevents any coke passing over the extractor unless regulated by the action of same. The extractor roller is formed of a series of cast-iron cross pieces mounted on a square shaft, each. cross piece having a slight lead on its neighbour so that a roller is formed with helical blades. The construction ensures that the discharge of the coke is the same throughout the whole of the revolution of the extractor roller, and, therefore, the travel of the charge through the retort is constant. The shaft of the extractor roller projects through, glands carried by side plates of the bottom Castings and on one end is fitted a wheel having a V-shaped groove turned in the rim. In this groove works an eccentric wedge-shaped pawl actuated by a rocking arm, the travel of which is varied by regulating a screw adjustment. The normal speed, of this extractor is one revolution in sixty to seventy minutes, but the screw adjustment allows of considerable variations fast or slow from the normal. Fig. 77.—Watek-sealed Dischakging Door. WOODALL - DuCKHAM System. to contain two or four hopper is fixed a water-It has been found in prac- In case of a breakdown of the gas engine or electric motor driving the extractor gear, the extractor can easily be turned by hand. The amount of power required to drive the coke extractors for a plant producing one million cubic feet of gas per day does not exceed one liorse power. The rocking arms previously described are coupled by short coimecting rods to a reciprocating bar running the length of the beuch settings. Each. reciprocating bar is driven by an adjustable eccentric fixed to the main driving shaft, the speed being about one complete stroke per minute, and the maximum length of the stroke about 4 inch.es, Below the coke extractor is fitted a cast-iron receiving hopper, which is constructed hours’ discharge of coke. To the bottom of the coke sealed gas-tight door (Fig. 77). tice that any form of faced door rapidly wears away and allows leakage to take place when the machined faces are subjected to the combined action of coke breeze and moisture. The construction of this water sealed door consists of two cast-iron boxes, the one fitting inside the other in such a way that an annular space is formed between them. In this space is fitted a segmental door plate constructed with. quadrant ends and suitable bearings and operating The door is sealed in 4 inches of water when closed, consequently it is gas-tight and needs no damping. The coke is never in contact with the water, but the latter has the beneficial effect of keeping the Castings cool. The time taken in discharging the coke from a retort is about ten seconds. On leaving the retort proper the coke is finally quenched by means of a small wheel.