Modern Gasworks Practice

CONTROL OF HORIZONTAL RETORT SETTINGS 141 Fürther investigations have been. conducted. by H. Poole, who finds a balance, due to libérated heat, of 3-C5 per cent. Poole’s balance of heat units is as follows :— In original coal before distillation, 13,260 B.Th.U. per Ib. After distillation, B.Th.U. recovered— In coke __________________________....... 8,296 B.Th.U. In tar __________________________...... 614 ,, In gas . . ... - 3,418 „ Lost in water, etc. . . . . . 527 „ __________ 12,855 B.Th.U. Unaccounted for ___________________..... 405 „ or 3'05 per cent __________ 13,260 B.Th.U. In recent tests with vertical retorts tlie Gas Investigation Committee have found that carbonization is endothermic, and the results obtained are in fairly close agree-ment with those of Barnum. These results show that of the heat value of the coal 1-8 per cent, is absorbed during carbonization. THE CURTAILMENT OF LOSSES The economical operation of the modern regenerator depends, perhaps, more upon its structural features than upon any refinements in its working which may subsequently be introduced ; for, more often than not, a producer is designed with but little thought to the many small yet telling items that count, with. the result that, liowever milch attention it may afterwards receive, it is never possible to economize beyond a moderate extent. The main point to be kept in view is the most effectual means for abstracting the maximum quantity of heat from the fuel— that is, the greatest possible proportion of its calorific value—and the utilization of this heat with the minimum of loss. On gasworks nowadays the fuels used, almost without exception, are coke and breeze ; although with the price of coal slack lower tlian that of coke, the Mond and such producers may be a familiar feature of the large gasworks of the future. Tar as an agent for retort or boiler heating may be dismissed from serious notice, as the price it is now commanding has rendefed its use miprofitable, although it became quite populär as a fuel some years ago. The price at that time, however, was 1<Z. (or less) per gallon ; now it is about ten times as much, and tar cannot compete with coke when costing more than 3d. per gallon. ITEMS FOR CONSIDERATION Owing to the different methods of firing now employed on gasworks, that is, whethcr individual or “ outside ” producers, generators or regenerators, it is difficult to lay down hard and fast mies of construction and working applicable to all systems ; but the principal heat losses liable to affect all types of producers may be stimmar-ized as follows :— 1. Incomplete combustion of carbon to CO.