Identifier: railroadengineer65newy (find matches)
Title: The railroad and engineering journal
Year: 1887 (1880s)
Authors:
Subjects: Railroad engineering Engineering Railroads
Publisher: New York : M.N. Forney
Contributing Library: Carnegie Library of Pittsburgh
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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e, radiatesome heat upon the boiler, but the heal radiated representshardly one-half of that absorbed, the rest being scatteredthrough the masonry wall and lost by exterior cooling. To (his class of boilers the principal objection consistsof the importance of the losses of heat resulting from themass of masonry. The losses are decreased in caseswhere the heating surface is large and the masonry sur-face is made as small as possible. The thickness of thewalls, moreover, and good joints help very much to dimin-ish the leakage or entry of air, and in consequence to im-prove the result obtained. Semi-tubular boilers generally give a very good result,especially if they are not driven too hard, and for that rea-son they should have a large heating surface. In orderthat the draft should not be interrupted too much by thereduction in section due to the passage into the tubes, thetotal section of the tubes should be at least 0.30 sq.m. persquare meter of grate surface. These boilers give still
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Q J • z cc < u m * J o z n o H Q ?; H b) O H s Z o cts C) bj o oz 5 u H $(/) QW_)UUX& DO Vol. LXV. No. II.) ENGINEERING JOURNAL. 501 better results when the passage of the gases into the tubesis not completed on the second course, but on the third,for then we do not have to fear the extinction of the flame orthe separation of the combustible gases, which are pro-duced when these gases enter the tubes at a very high tem-perature. Masonry furnaces permit the use of coal of a poor qual-ity, which could not be properly burned in a tubular boiler.fn some cases externally fired boilers are found producingresults almost as good as tubular boilers, and they cer-tainly have the merit of simplicity in construction andcomparative cheapness. The tubular boiler with interior fire-box occupies muchless space than an externally fired boiler, and for that rea-son alone it is often preferred. In every boiler of thisclass

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