Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGDRUM SAFETY VALVES ECONOMIZE!! INinSTEAM DRUMSCRUBBEI! ELEMENTSURFACE BLOWOFF PIPECYCLONE STEAM SEPARATORINTERNAL FEED PIPESTEAM COLLECTING BAFFLEAIR INLn TO VDOUBLE CASING\MODEL IN SOOT BLOWERSTEAM DRUMPROTECTION PLATESSUPERHEATED-SIDEFURNACEFURNACE PEEP HOLE SOOT BLOWERELEMENTSHIGH TEMPERATUREINSULATING BRICKSTUD TUBEWATER COOLEDSIDE WALLPLASTIC CHROME ORFDOWNCOMERWATER WALL HEADERIMPELLER PLATESATURATED-SIDEFURNACESUPERHEATERTUBE SUPPORTSBURNER, BEADEDCONEDENSE FIREBRICKHIGH TEMPERATUREINSULATING BRICKWATERDRUMUNCALCINEO DIATOMACEOUSEARTH BLOCKSBRICK BOLTWATER SCREEN HEADERPROTECTION PLATES t BAFFLE MIXBOTTOM BLOWOFFCONNECTIONBURNER AIR DOORSFUEL OIL BURNERSeECIAl OIL BURNER LIGHTING PORTAIR LOCK TYPESM-WATER WALL HEADERDRAIN CONNECTION PLASTIC CHROME OREWATER SCREEN HEADERBLOWOFF CONNECTIONDOWNCOMERSFigure 10-19.— Double-furnace boiler (cutaway view).furnaces— one for the saturated side and one forthe superheater side. It has controlled superheat.It operates at a pressure of about 615 psig, andis often called a "600-psi boiler."The most important advantage of the doublefurnaceboiler arises from the fact that theseparate firing of the superheater side allowspositive control of the degree of superheat. Inthe double-furnace boiler, it is theoretically250FURNACE ACCESS DOORSTDNTUBE WATER-COOLEDDIVISION WALL38.38Xpossible to maintain the maximum designedtemperature at the superheater outlet underwidely varying conditions of load. In a singlefurnaceboiler, where one source of heat is usedboth for generating the steam and for superheatingit, the degree of superheat increasesas the rate of steam generation increases; andhence the maximum designed temperature at thesuperheater outlet is normally reached only atfull power.