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How Efficient is an old-style coal-fired steam boiler?

  1. Sep 23, 2009 #1
    I've been looking around for any hint of this kind of thing, for a story I'm planning to write, and while I can ignore discrepencies between, say, actual history and events in my story, my inner scientist won't let me ignore this!

    The situation is as follows; imagine an early industrial revolution era steam boiler, like the ones used in early steam locomotives, burning coal found on and near the surface of the ground (lignite, sub-bituminious, not quite sure on that either). I can find the energy values of coal, and efficiencies of modern steam boilers, but nothing about old ones, so I would like to know is:

    1. How much of the energy from the coal would actually reach the steam as useful kinetic energy?

    2. How quickly do the boilers go through coal, and how much would they need to keep it burning for an hour without getting too hot or too cold?

    These are complex questions, I know, which is why I need help with them!
  2. jcsd
  3. Sep 23, 2009 #2
    Hi Xodian-
    Conventional coal fired utilities are about 10,000 BTU per kilowatt-hour output (about 32% efficiency). Some modern ones may be as low as 8,000 Btu per kilowatt-hour output. The major limit to maximum efficiency is thermodynamic; Carnot (Rankine) cycle. See
    Bob S
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