Page:1902 Encyclopædia Britannica - Volume 27 - CHI-ELD.pdf/469

 DESTRUCTORS dryin" on the hearth pass through the fire and over the red-hot fire-bridge, which is perforated longitudinally with air-passages connected with a small flue leading from a grated opening on the face of the brickwork outside ; in this way an auxiliary supply of heated oxygen is fed into the combustion chamber. This chamber, in which a temperature approaching 2000° F. is attained, is fitted with large iron doors, sliding with balance weights, which allow the introduction of infected articles, bad meat, etc., and also give access for the periodical removal of fine ash from the flues. The high temperatures attained are utilized by installing one boiler, preferably of the Babcock and Wilcox watertube type, for each pair of cells, so that the gases, on their way from the combustion chamber to the main flue, pass three times between the boiler tubes. A secondary furnace is provided under the boiler for raising steam by coal, if required, when the cells are out of use. The grate area of each cell is 25 square feet, and the consumption vaiies from 16 up to 20 tons of refuse per cell per 24 hours. In a 24-hours’ test made by the superintendent of the cleansing department, Leeds, at the Warrington installation, the quantity of water evaporated per pound of refuse was 1T4 lb,

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the average temperature in the combustion chamber 2000 F. by copper-wire test, and the average air pressure with forced draught, 2lj inches (water gauge). At Leyton, which has a population of over 100,000, an eight-cell plant of this type is successfully dealing with house refuse and filter press cakes of sewage sludge from the Sewage Disposal Works adjoining, and even with material of this low calorific value the total steam-power produced is considerable. Each cell burns about 16 tons of the mixture in 24 hours and develops about 35 indicated horse-power continuously, at an average steam-pressure in the boilers of 105 lb. The cost of labour at Leyton for burning the mixed refuse is about Is. 7d. per ton ; at Llandudno, where four cells were laid down in connexion with the electric-light station m 1898, it is Is. 3|d., and at Warrington, 9|d. per ton of refuse consumed. Combustion is complete, and the destructor may be safely installed in populous districts without nfiisance to the inhabitants. Further patents (Wilkie’s improvements) have been obtained by Meldrum Brothers (Manchester) in connexion with this destructor. In addition to the above-described destructors, other modern

Fiq. 5.—Leyton Destructor—Block Plan, showing general arrangement of the works forms have been introduced from time to time, but adopted to a the reverberatory arch of the cell of the width of the truck, less degree ; amongst these may be mentioned Hanson’s Utilizer, situated over the drying hearth, is formed by a firebrick arch Mason’s Gasifier, the “ Bennett-Phythian,” Cracknell’s (Mel- fitted into a frame capable of being moved backwards and forwards bourne, Victoria), Coltman’s (Loughborough), Willoughby’s, and by means of a lever. The charging truck, when empty, is Healey’s improved destructors. On the continent of Europe, brought under the tipping platform, and the carts tip directly systems for the treatment of refuse have also been devised. into it. When one of the cells has to be fed, the truck is moved Among these may be mentioned those of M. Defosse and M. along, so that one of the divisions is immediately over the feeding Helouis. The former has endeavoured to burn the refuse in opening, and the wheel holding up the bottom doors rests upon large quantities by using a forced draught and only washing the the central rail, which is continued over the movable covering arch. smoke.1 Helouis has extended the operation by using the heat Then the movable arch is rolled back, the doors are released, and from the combustion of the refuse for drying and distilling the the contents are discharged into the cell, so that no handling of the refuse is required from tipping to feeding. This apparatus material which is brought gradually on to the grate. Boulnois and Brodie’s improved charging tank is a labour- is in operation at .Liverpool, Shoreditch, Cambridge, and elsesaving apparatus consisting of a wrought-iron truck, 5 ft. wide where. Various forms of patent movable fire-bars have been employed by 3 ft.^2deep, andsupply of sufficient length holdwhich not less nes, rue or j-j hours’ for the two to cells it in destructor furnaces. Among these may be mentioned Settle’s,2 ian 3 Vicar’s, Riddle’s rocking bars,4 Horsfall’s self-feeding appa5 ories8 serves. The truck, which moves along a pair of rails ratus, and Healey’s movable bars;6 but complicated movable laid across the top of the destructor, may be worked by arrangements are not to be recommended, and experience greatly one man. It is divided into compartments holding a charge of refuse in each, and is provided with a pair of doors in the bottom, favours the use of a simple stationary type of fire-bar. opening downwards, which are supported by a series of. small 2 wheels running on a central rail. A special feeding opening in 3 Patent No. 15,482 (1885). Patents No. 1955 (1867) and No. 378 (1879). 4 5 1 Patent No. 20,207 (1892). Compte Rendu des Travaux de la Societe des Ingmieurs Civils de 6 Patent No. 4896 (1891). Patents No. 18,398 (1892) and No. 12,990 (1892). France, folio 775 (June 1897).