. The railroad and engineering journal . y encounter a large surfaceof a much lower temperature. The difference is not somarked in boilers of the Cornish type or in those withoutlubes or with return flues, but it still exists to some extent. travel from the layer of coal on the grate to the smoke-stack. It is evidently because these gases on leaving thegrate come immediately in contact with the boiler, whichis, as we have said, a body sufficiently cool to partly ex-tinguish these gases. We see, in fact, that the boiler atthe pressure of 75 lbs. is at near 150° C, while carbonicoxide will not b
. The railroad and engineering journal . y encounter a large surfaceof a much lower temperature. The difference is not somarked in boilers of the Cornish type or in those withoutlubes or with return flues, but it still exists to some extent. travel from the layer of coal on the grate to the smoke-stack. It is evidently because these gases on leaving thegrate come immediately in contact with the boiler, whichis, as we have said, a body sufficiently cool to partly ex-tinguish these gases. We see, in fact, that the boiler atthe pressure of 75 lbs. is at near 150° C, while carbonicoxide will not burn until it is at least at 800° C. and thehydrocarbons at 700 C, on account of the extreme disper-sion of their particles. It follows then that the gaseswhich leave the fire-box at a very variable temperature,not often at over 800 C, lose very quickly in contact withthe boiler heat enough to reduce them to the temperaturewhere they can no longer combine with oxygen. If it ispossible then the complete combustion of all the gases leav-. MORTUARY STATION, SYDNEY, NEW SOUTH WALES. STREET FRONT. While internal fire-boxes are favorable to the rapid ab-sorption of heat, they have also some height above the grate cannot be much more m., and we cannot use in them coals with a largeproportion of gas, since the gases on coming in contactwith the plates are cooled and cease to burn. The fuel tobe employed in such boilers should have only a small pro-portion of volatile matter and should burn easily, sincethe walls of these fire-boxes do not attain a temperatureof over 152° C, while in external fire-boxes the radiatedheat of the brick walls will rise to 600° C, which is animportant aid to combustion. Let us see why the combustible gases and the oxygenof the air in excess do not combine in the path which they ing the fire must be effected before they are cooled belowthe temperature where the fire is extinguished, whether itbe 800° or 700°. For the oxidation
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1887
