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Principles of naval engineering - Historic Naval Ships Association

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PRINCIPLES OF NAVAL ENGINEERINGECONOMIZERSTEAM DRUMSUPERHEATERELEMENTSDOWNCOMERROOF, SIDE &REARWATERWALLTUBESCASINGBURNERSDESUPER-HEATERSADDLEWATER DRUMREFRACTORYREAR WALLHEADERSUPERHEATERHEADERSWATER SCREENHEADERSIDE WALLHEADERFigure 10-23.— Newer single-furnace boiler with vertical superheater.147.84subject to modification and improvement. Thenew types <strong>of</strong> boilers discussed here do not byany means exhaust the field <strong>of</strong> new designs;indeed, it must be emphasized that a wide diversity<strong>of</strong> design is still possible in this field.TOP-FIRED BOILERS.— A new boiler designwhich is at present being used on some auxiliaryships is the top-fired boiler. In this boiler, thefuel oil burners are located at the top <strong>of</strong> theboiler and are fired downward. The top-firedboiler utilizes certain new construction techniques,including welded walls. The boiler is <strong>of</strong>the natural circulation type, with a completelywater-cooled furnace. The only refractory materialthat is exposed to the gases <strong>of</strong> combustionis the refractory that is installed in cornersand in a small area around the burners. Thetop-fired boiler has an in-line generating tubebank and a vertical superheater. It is expectedthat the top-fired boiler will be much cleanerand thus require less maintenance than olderboilers <strong>of</strong> more conventional design.CONTROLLED CIRCULATION BOILERS,-ControUed (or forced) circulation boilers have256

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