The Mechanical Handling and Storing of Material

THE HANDLING OF HOT COKE IN GASWORKS 145 The late Mr G. E. Stevenson, formerly engineer of the Gaythorn Gasworks, has stated that the saving effected by substituting a conveyor for hand labour in wheeling the coke from the retort house to the yard, amounted to 4|d. per ton of coke handled, this being the difference between the wages of the twelve men formerly employed and the cost of the conveyor now used, together with the wages of the one man employed to superintend the whole of the machinery. In the method of removing coke by hand usually employed in gasworks, one man rakes the coke out from the retort into a barrow placed under the mouthpiece, whilst a second man quenches it with water from a hose or bucket, after which it is wheeled out of the retort house into the yard. The first improvement on this method was the adoption of cage-like tipping-barrows or trucks, running on narrow gauge rails either in front of the retorts or on the furnace floor below. The hot coke is discharged directly into these trucks, in the latter case through suitable openings in the floor, each truck generally holding the contents of one retort. The truck is then pushed outside the retort house, and the coke is there quenched with a spray of water, the truck meanwhile standing over a grating connected with a drain which leads away the surplus water. Above the truck is an inverted funnel with an uptake to lead away the fumes and vapour. When the coke is completely quenched, the truck is pushed to the coke heap and its contents are there tipped, or sometimes the trucks are elevated by means of a lift to the level of the coke hoppers or stock heap, and discharged on to either. In addition to manual or animal labour, endless rope haulage has been employed, and in some cases small locomotives have been used. For large gasworks these methods are altogether inadequate, and the mechanical equipment of such works cannot be regarded as complete without suitable hot coke conveyors and overhead bunkers for holding the coke ready for loading into trucks or carts. Very few of the earlier installations for the mechanical handling of coke are still in use, most of them having been discarded after a short period of troublesome and expensive working. The first hot coke conveyors of note were built about the year 1898, and were of the push-plate type (see Fig. 76), having a trough 27 in. in width composed of cast-iron sections, and push-plates of malleable cast iron. The latter were attached, at 24 in. pitch, to a central chain, and were dragged along on a renewable wrought-iron bar, the wear on the chains being taken by iron blocks fixed to the links and capable of being replaced when necessary. The return strand of the conveyor was led over guide pulleys, either underneath the bench floor or high up out of the way of the retorts. The speed at which these conveyors ran was about 48 ft. per minute, and their capacity was about 20 tons per hour. They performed their work well, but were unsatisfactory in other respects. Their life was short, under the trying conditions to which they were subjected, and the expenditure on repairs and renewals of parts was very heavy. The chain, being central, suffered severely from the action of the hot coke, to which it was fully exposed. The first complete installation of this kind was erected at the Gaythorn Gasworks in 1898, to the design of the late Mr G. E. Stevenson ; this plant was discarded in 1903 for the reasons above mentioned, and also on account of the excessive breakage of the coke. The conditions to be aimed at in the design of a hot coke conveyor are : simplicity; small number of wearing parts; interchangeability of wearing surfaces and of worn and broken parts; protection of wearing and working parts from contact with the hot coke; and ability to keep the temperature of the conveyor itself as even as possible, in order to avoid distortion of its parts through sudden heating or cooling. The latter conditions can, in the Author’s opinion, only be attained in conveyors of the push-plate type, in 10