The Mechanical Handling and Storing of Material

39° THE MECHANICAL HANDLING OF MATERIAL explain the diagram, after the full description which has been given of the Goodall machine. Some of the latest coke-handling plants have been designed with a view of excluding the air more effectually during the quenching process, to produce coke of silvery colour as obtained from the old-fashioned beehive ovens. The first installation on these lines was that by Moore, erected in an American cokery, but its very high cost is against its more general adoption. The machine has been simplified by Humboldt. The quenching chamber into which the entire contents of an oven are pressed is enclosed and filled with vapour or steam created during the quenching process, so that the air is completely excluded, and the quenching apparatus proper is suspended within the interior of the receptacle. As soon as the cake of coke is completely enclosed and quenched the apparatus is driven to the end of the battery where it is tilted sufficiently for the coke to slide out by gravity, either over screens and into trucks or on to conveyors. The quenching water is pumped by the apparatus from an open water trough by a centrifugal pump, and the surplus water is returned to a similar trough, and after passing a settling tank the clean water is returned into the first water trough again. With such an installation it is obvious that the coke siding cannot be in front of and parallel with the hearth, but must be at right angles, and at the side of the battery. The whole machine is mounted on twelve wheels running on three rail tracks at a speed of 160 ft. per minute, and only one man is required to attend to the machine, which is capable of serving a battery of one hundred ovens. A still more effectual exclusion of the air is obtained by complete submersion of the coke in water. This process has been in use for some time in gasworks, but it has lately been applied on a larger scale to coke ovens with great success. An essential feature of the process is that both coke and quenching water leave the machine at so high a temperature that the moisture still adhering to the coke is evaporated by the latent heat in the coke. During the experimental stages, when submerging large quantities of incandescent coke, explosions occurred sufficiently violent to throw the coke and water out of the quenching receptacle, but, as might be expected, it has been found that if the coke is slowly submerged so that the steam can escape through the interstices of the incandescent coke, these explosions do not occur, and the coke so quenched is of a firm quality and in large pieces. This is explained by Schöndeling, the pioneer of the system, to be owing to the gentle action of quenching; the steam rising from the portion first quenched being superheated, by passing through the still incandescent coke, to such an extent that the difference of temperature between the coke and the quenching medium is comparatively small, and its quenching action very gradual, whilst chilling the coke from above will contract it suddenly and make it brittle. The first plant on the Schöndeling system was erected in 1910 at the Gasworks, Agram, in Germany, and a typical installation of the kind is shown in Fig. 551. The coke receptacle a is composed of double walls, and takes the whole charge of an oven. There is a communication between the double wall space and the lower portion of the receptacle, so that the little water contained at the beginning in the space between the walls will quench the coke in the bottom of the receptacle; the quenching tanks d are large enough to contain sufficient water to quench three or four charges without replenishing. When the oven door has been opened and the machine placed in position the pushing is commenced, and the coke enters through the passage e into the coke receptacle a, which rests in the water tank k during the filling. The quenching process