Mechanical Draft; A Practical Treatise

Mechanical Draft; A Practical Treatise

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ... d The theoretical velocity with which the external air would enter the chimney, if no resistance existed, may be expressed by the equation--In which v = velocity, in feet per second. g = the acceleration due to gravity = 32.16. H'= head, or distance fallen, in feet. The preceding deductions are based upon the assumption that there is no resistance to the movement of the air. Such a condition evidently cannot exist in the operation of the ordinary chimney. The motion of the gases creates a certain back pressure due to their friction on the inner surface of the chimney. This back pressure must be deducted from that due to the difference in density in order to ascertain the effective pressure which may be applied to compel the air to pass through a boiler furnace and up the chimney. The effective pressure which in any given case is necessary to overcome the frictional and other resistances of the air in its passage through the fuel, the boiler tubes and other portions of the boiler, and impart to the gases the necessary velocity of entrance and exit, must depend upon the existing conditions of character of fuel, design and proportions of boiler, and other considerations which render exact determination extremely difficult. Chimney Design.--From the preceding it is obvious that a chimney must be so designed as to create sufficient draft or pressure difference to overcome all resistances, and in addition impart the necessary velocity to the required amount of air. The number of pounds of coal which can be burned in a given time on a given grate equals the weight of air forced through, divided by the number of pounds of air required for the combustion of a pound of coal under the given conditions. As already shown, this latter amount may vary all the...show more

Product details

  • Paperback | 112 pages
  • 189 x 246 x 6mm | 213g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236634233
  • 9781236634238