PRINCIPLES OF NAVAL ENGINEERING 



MANUAL 



OPERATION- 



LEVER 



ACTUATING 

 LINE 



ACTUATOR 



TO ATMOSPHERE 



TO ATMOSPHERE 



ACTUATING 

 VALVE 



ATMOSPHERE 



DRUM PRESSURE 



SUPERHEATER OUTLET PRESSURE 



104.2? 

 Figure 11-22.— Three-valve superheater outlet safety valve assembly (Consolidated). 



Before instructing fireroom personnel to 

 blow tubes, the engineering officer of the watch 

 must obtain permission from the officer of the 

 deck. Under some conditions, tubes cannot be 

 blown without covering the upper decks with soot; 

 hence the need for obtaining permission from the 

 officer of the deck. 



Soot blowers are installed on the boiler with 

 their nozzles projecting into the furnace between 

 the boiler tubes or adjacent to them. The soot 

 blowers are arranged so that operation in the 

 proper sequence will sweep the soot progres- 

 sively toward the uptakes. 



The number of soot blowers installed, the 

 way in which they are arranged, and the blowing 

 arcs for each unit differ from one type of boiler 

 to another. Figure 11-23 shows the arrangement 

 of soot blowers used on one of the newer 1200-psi 

 single-furnace boilers; one of the soot blowers 

 has a blowing arc of 220° and the others have 

 blowing arcs of 360° F, on this particular boiler. 



One common type of soot blower is shown in 

 figure 11-24. The part of the soot blowerthat may 

 be seen from the outside of the boiler is called 

 the head. The soot blower element, a long pipe 

 with nozzle outlets, is the part of each soot 

 blower that projects into the tube banks of the 

 boiler. The soot blower shown in figiire 11-24 is 

 operated by an endless chain; when the chain is 

 pulled, the element is rotated and superheated 

 steam is admitted through the steam valve. The 

 steam discharges at high velocity from the 

 nozzles in the elements. The nozzles direct the 

 jets of steam so that they sweep over the tubes. 

 The soot is thus loosened so that it can be blown 

 out of the boiler. 



Some soot blowers are operated by turning a 

 crank or handwheel, instead of by an endless 

 chain. On some recent ships, the soot blowers are 

 operated by pushbuttons. One pushbutton is pro- 

 vided for each unit. Pressing the pushbutton^ 

 admits air to an air motor which drives the units. 



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