Modern Gasworks Practice

140 MODERN GAS WORKS PRACTICE A comparison between Euchene’s figures and those of Barmini is given below. The former are converted from K.C.U. per 100 kilogrammes to B.Th.U. per 100 lb., so that both sets are expressed in similar units. Regenerative Settings. ___________ _____________________ _______ _________ _______ _______ Euchéne. ! Babnum. ___________________ ____________________________________ Heat eontained in fuel....................... Heat lost— In ashes .................................. In flues..................................... In volatile matter........................... By radiation......................... Heat in coke........................... Total heat expended.......................... Absorbed during distillation......................... Dispersed during distillation......................... ___________________________ B.Th.U. per 100 lb. ________ _________ 180,547 ■ 215,623 2,131 58,768 122,377 32,398 23,333 45,550 20,931 44,253 33,708 183,100 200,349 — 15,274 2,553 — ______________________ ________ _________________________ __________ ________ The chief point to be noticed is that whereas Buchene finds heat to be liberated, Barnum’s results indicate an absorption due to distillation. Undoubtedly both exothermic and endothermic reactions occur simultaneously during carbonization'; but more recent autliorities disagree as to the ultimate thermal nature of the process, so that its actual nature is still open to question. Research in this direction has been carried out by Cobb and Hollings, wlio conclude that the exothermic reactions commence at 600° C. and continue until some high, temperature is reached; but at 7o0 C. endothermic reactions cominence which mask the exothermic effect above that temperature. Moreover, whilst prolonged heating at 7E0° C. does not effect a completion of the exothermic reactions, it would appear that it cloes complete the endothermic reactions, since after heating at 750° C. there is some evidence of exo-thermic reactions up to 900° C. In the item total heat supplied ” in Eucliene’s figures it should be mentioiied that the percentage attributed to “ volatile products ” indicates the quantity of heat evolved in the retort owing to the supposed nature of the reactions ; that is, it is the heat of the formation of the original coal, which is liberated by the process oi ■carbonization. Mahler in his researches observed a loss of 3 j per cent, of the original heat units in coal due to carbonization, which he looked upon as representative of the heat liberated by the process. This figure, however, takes no account of “ scurf ” deposited in the retorts, or of naplitlialene, for botli of which some reduction must be made.