Modern Gasworks Practice

THE MECHANICAL HANDLING OF MATERIALS 281 A question of considerable importance is the amount of Capital outlay which. is permissible in order to save the wages of a single man. At the time of writing the ordinary labourer is'receiving ls. 8Æ. per hour, he works 47 hours per week; and (in order to include all extras, such as Insurance, holiday pay, etc.) a year may be assumed to contain 54 working weeks. The outgoings on one man (apart from overtime) amount, therefore, to about £210. per annum. On the other hånd, the charges on Capital have shown to be adequately met in cases of mechanical handling by setting down 5 per cent, for interest, 5 per cent, for wear and tear, and 7| per cent, for depreciation, i.e. a total of 17per cent. Each year, however, the sum upon which interest has to be paid is written ofi by 6| per cent. ; thus during the fourteen years over which the Capital is paid back, the average rate of interest is only 2J per cent., making the total average charges on Capital 14| per cent. Acenrdingly; the Capital expenditure permissible in order to eliminate one man is rather more than £1,400—the charges on this sum at 14| per cent, amounting approximately to the equivalent of a labourer’s annual earnings. As an éxample of the economy in labour to be effected on large works, the case of the 500 million works considered in Chapter I may be taken. The coal gas made per diem in this instance amounts to 1,600,000 cubic feet, and the total outlay involved in elevators, conveyors, coal breakers, charging machinery, power plant, and coke-handling plant is given as £20,350. Allowing the normal figures of 5 per cent, for interest on Capital, 5 per cent, for maintenance, and 7| per cent, for depreciation (i.e. a total of 17j per cent.), the annual saving which must be effected is £3,560. This means a reduction in numbers of about 16 or 17 men, or (say) 5 or 6 men from each stift per day. About 30,000 tons of coal per annum would be håndled, which means that a saving of 28 d. per ton is necessary to.meet the above expenditure. Accordingly, those in authority would have to be positively assured that such a saving would follow the introduction of machinery. On the works in question there is little doubt that this economy—amounting to about 2^d. per 1,000 cubic feet of gas produced—could be effected. Labour-saving machinery may be applied on gasworks for the following pur-poses :— (a) The charging and discharging of retorts. (b) The conveyance of coal from point of delivery to point of consumption. (c) The breaking up of coal to the required size. (cZ) The conveyance of coke from the retorts to a suitable storage place, or to other machinery for grading, screening, or washing. (e) Labour-saving appliances in the retort house, such, as mechanical pokers, also oxide and sulphate of ammonia handling plant. The mechanical handling machinery introduced in gasworks is almost solely used in connection with the retort? house, although on larger works other raw materials or by-products, such as oxide of iron or sulphate of ammonia, may be profitably dealt with in this manner. In faet, in any instance where a saving can be shown, after consideration on lines sucH as those already indicated, the instalment of machinery is justified.