PRINCIPLES OF NAVAL ENGINEERING 



ECONOMIZER 



STEAM DRUM 



SUPERHEATER 

 ELEMENTS 



DOWNCOMER 



DESUPER- 

 HEATER 



ROOF, SIDE & 



REAR 



WATERWALL 



TUBES 



CASING 



BURNERS 



SADDLE 



WATER DRUM 



SUPERHEATER 

 HEADERS 



REFRACTORY 



REAR WALL 

 HEADER 



WATER SCREEN 

 HEADER 



SIDE WALL 

 HEADER 



147.84 



Figure 10-23.— Newer single-furnace boiler with vertical superheater. 



subject to modification and improvement. The 

 new types of boilers discussed here do not by 

 any means exhaust the field of new designs; 

 indeed, it must be emphasized that a wide diver- 

 sity of design is still possible in this field. 



TOP-FIRED BOILERS.— A new boiler design 

 which is at present being used on some auxiliary 

 ships is the top-fired boiler. In this boiler, the 

 fuel oil burners are located at the top of the 

 boiler and are fired downward. The top-fired 

 boiler utilizes certain new construction tech- 

 niques, including welded walls. The boiler is of 



the natural circulation type, with a completely 

 water-cooled furnace. The only refractory mate- 

 rial that is exposed to the gases of combustion 

 is the refractory that is installed in corners 

 and in a small area around the burners. The 

 top-fired boiler has an in-line generating tube 

 bank and a vertical superheater. It is expected 

 that the top-fired boiler will be much cleaner 

 and thus require less maintenance than older 

 boilers of more conventional design. 



CONTROLLED CIRCULATION BOILERS,- 

 ControUed (or forced) circulation boilers have 



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