Steam:
Its Generation and Use

ECONOMY IN STEAM. Efficiency of the Boiler. One pound of pure carbon when burned yields 14,500 heat units, each of which is equal to 772 foot pounds of energy. One pound of carbon, if all its heat was utilized in power, would there- fore exert 5.65 horse-power for one hour, instead of from to %, as in the best ordinary practice. The 14,500 heat units would, if all utilized in a boiler, evaporate 15 pounds of water from 2120 at atmospheric pressure. A boiler which evap- only two exceptions, on boilers in daily use for manufacturing purposes, in England, Scotland, and from Massachusetts to California in the United States, with various kinds and grades of coals, and at various rates of combustion, cover- ing an aggregate of nearly three months’ regular working, and evaporating over three thousand tons of water, gave an average evaporation of 11.4217 pounds water per pound of combustible. This is within four per cent, of Rankine’s stand- ard, and within seven and one-half per cent, oj the highest theoretical efficiency, under the con- Babcock & Wilcox Boilers, 272 H.P. at Worombo Mfg. Co., Lisbon Falls, Me. orates 7X pounds of water for each pound of combustible, utilizes but 50 per cent, of the total heat, and this is about the average result of shell boilers now in use. The Babcock & Wilcox boilers, in thirty tests extending over the last twelve years, under a great variety of conditions and circumstances, by no less than twenty different engineers, and, with ditions in which they were made. It is not prob- able that any kind of boiler, fairly tested, will ever beat such a record. As about 15 per cent, is lost in the chimney gases, and in radiation, it is evident that all claims to over 12% pounds evap- oration should be looked upon as unreliable. A steam generator is composed of two distinct parts, each with its independent function. 1 he