Transactions . were transmitted to the pieces heated. The utiliza-tion of heat in the furnace was therefore about 26 per cent., whileabout 17,000 h. u., or 25 per cent., were consumed in the production•of steam. The total heat-utilization was therefore about 51 per figures have approximate value only, since the temperature ofthe material as charged and as withdrawn was merely estimated. If the calculation be pursued further, and 10 per cent, of C09 beassumed in the gas at the end of the boiler (after complete combus-tion), it is found that there is a loss of about 19 per cent, in th
Transactions . were transmitted to the pieces heated. The utiliza-tion of heat in the furnace was therefore about 26 per cent., whileabout 17,000 h. u., or 25 per cent., were consumed in the production•of steam. The total heat-utilization was therefore about 51 per figures have approximate value only, since the temperature ofthe material as charged and as withdrawn was merely estimated. If the calculation be pursued further, and 10 per cent, of C09 beassumed in the gas at the end of the boiler (after complete combus-tion), it is found that there is a loss of about 19 per cent, in the gasesescaping at about 300° C. from the boiler. Hence the loss byradiation, conduction, and uuburned residues is 100 — 51 — 19 = 30 VOL. XLVII.—10 290 GENERATION OF STEAM BY WASTE HEAT FROM FURNACES. per cent, That is to say, the loss by radiation, conduction, etc., forboth furnace and boiler, is 30 per cent., of which about three-fourths-is to be charged to the furnace, and one-fourth to the The furnace in Fig. 1 having a long hearth per se, there is no dis-crepancy of size between furnace and boiler; but in the case of asmaller furnace, this boiler (a 2-fire-tube boiler, from 8 to 9 m. long)would seriously over-balance the furnace, or else the boiler would GENERATION OF STEAM BY WASTE HEAT FROM FURNACES. 291 have to be shortened, with a considerable diminution of heating-sur-face. But in the presence of a large quantity of gas at high temper-ature, the heating-surface must be correspondingly large, in order toconvey a large amount of heat to the boiler-water. This circum-stance has led to the adoption of water-tube boilers, which permit fora given ground-area a great development of heating-surface, and areadapted to the highest steam-pressures. Fig. 2 shows the combination of a furnace with a Diirr water-tubeboiler placed partly over and partly behind it. Since, in this instance,the available space was not sufficient for water-tubes of the normallength of
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
