Modern Gasworks Practice

N) MODERN GAS WORKS PRACTICE should be laid out for wliat it is comfortably capable of, so that each piece of plant may have room for extension. up to that limit. Cartage ways and other means of access must, if possible, be left around all buildings. Boilers should be central for feeding exliausters, mechanical washers, sulphate plant, pumps, etc. ; whereas gasholders should be kept on the side towards the populated parts, thus partly shielding the works, with the purifiers and sulphate plant far away from entrance gates and roads. Plenty of room should be left near the purifiers for laying out oxide, a generous portion of this being under cover. A point which is often overlooked is that of keeping the gasholders as far as possible from the causes of corrosion, such as the water-gas plant, chimneys, sulphate plant, etc. ; whilst purifiers should be some distance from the boiler houses. The ideal place for scrubbing plant, iri faet all plant for the extraction of tar and ammonia, is next to th.e storage wells—thus avoiding long distances for pumping. It is scarcely necessary to add the warning that all Underground tanks should be kept out of the line of heavy traffic. CAPITAL COSTS OF WORKS To arrive at a decision with regard to the plant to be laid down entails mueh more consideration since the introduction of the Gas Regulation Act. This Act gives freedom to an undertaking to declare any calorific value it chooses; the provision of plant, therefore, is dependent upon various considerations, amongst which the following are the more important (a) The special demands of the district to be served, whether industrial or domestic. Also any particular demands for special industries. (6) The relative values of coal and by-products. (c) The Capital cost for various carbonizing installations, i.e. horizontal retorts, vertical retorts (both with and without steaming), water gas (blue or carburetted), ■complete gasification plant. (<Z) The size of trunk mains, and the sizes of cohsumers’ services, meters, and heating appliances. The thermal balance of all methods included under (c) must be considered in relation to the cost of coal and residuals, Capital expenditure entailed, manufacturing wages, flexibility of control, and other factors. In the following case a typical instance is considered of an undertaking declar-ing a calorific value of 475 B.Th.U. per cubic foot, the conditions being complied ■with as follows :— 3 parts of straight coal gas of 530 B.Th.U. per cubic foot brought down with 1 part of blue water gas, slightly carburetted water gas, or gas from a complete gasification plant with a calorific power of, say, 340 B.Th.U. This gives an average mixed gas of about 482 B.Th.U. per cubic foot, i.e. a slight margin above the “ declared ” calorific value. The above-mentioned proportion of lower grade gas gives a certain amount ■of flexibility in manufacture, and in this way allowance may be made for bad coals,