Chapter 11-BOILER FITTINGS AND CONTROLS 



DRY PIPE 



STEAM 



STEAM 



WATER 



SURFACE BLOW 

 LINE 



INTERNAL FEED 

 PIPE 



GENERATING 

 TUBES 



Figure 11-3.— Flow of steam and water in steam drum 

 of double-furnace boiler. 



38.44 



scrubber, its direction is changed frequently, 

 and with each change of direction some mois- 

 ture is lost. The steam passes out of the 

 scrubber element into the top part of the steam 

 drum and then enters the dry pipe. 



While the steam is rising, the water is fall- 

 ing to the base of the separator. Stationary 

 curved vanes in the bottom of the separator 

 serve to maintain the rotary motion of the water 

 until the water is finally discharged from the 

 bottom of the separator. Since the vanes are 

 located around the periphery of a flat plate, the 

 water passes from the separator only around 

 the outer edge. The flat plate also serves to 

 keep the steam, which is in the center of the 

 separator, from being carried downward with 

 the water. 



A flat baffle plate is fitted at the base of 

 each of the two end separators on each side. 

 This baffle plate guides the water that is being 

 discharged from the separator to the center of 

 the drum, where it mixes thoroughly with the 

 rest of the water in the drum. Without such a 

 baffle, the water from these end separators 

 would tend to flow directly to the downcomers 

 and, since it is hotter than the rest of the water 

 in the steam drum, it would tend to disrupt the 

 boiler circulation. 



Figure 11-6 illustrates the arrangement of 

 internal fittings in an older single-furnace 

 boiler. The internal fittings for this boiler are 

 quite similar to those found in the double-fur- 

 nace boiler, except that the single-furnace boiler 

 has a desuperheater (item 5 in fig. 11-6). 



The internal fittings in the steam drum re- 

 quire routine maintenance and upkeep. All main- 

 tenance requirements shall be conducted in 

 accordance with the Planned Maintenance Sub- 

 system of the 3-M System. 



When a boiler is opened for cleaning of 

 watersides, the internal fittings must be re- 

 moved. The fittings are bolted into place; re- 

 moving the bolts allows you to remove the 

 fittings. Be sure that all bolts and tools used 

 in removing the bolts are strictly accounted 

 for. When removing internal fittings, be sure to 

 identify them so that you will be able to rein- 

 stall them correctly. 



After removing the fittings from the steam 

 drum, thorouglily wirebrush and clean them. 

 Check the dry pipe, the internal feed line, and 

 the surface blow line to be sure that all the 

 holes are free and clear of obstructions. In 

 addition, inspect the inside of the feed line for 

 oil accumulations; if you find any sign of oil 

 notify the CPO in charge of the fireroom. 



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