Chapter 9-MACHINERY ARRANGEMENT AND PLANT LAYOUT 



NO. 2 

 FIREROOM 



TURBOGENERATOR 



SUPERHEATED 



TURBOGENERATOR 



STEAM- 



CROSS-CONNECTION < 



PIPING CONNECTING ^ 



FORWARD PLANT AND uj 

 AFTER PLANT 



SUPERHEATED STEAM TO 

 SOOT BLOWER HEADER 



NO. i EN6INER00M 



^i. 



SATURATED 



STEAM TO 



SUPERHEATER 



SAFETY VALVE 

 CONNECTION 



SUPERHEATED 

 ■STEAM TO 

 DESUPERHEATER 



-MAIN STEAM STOP 



^SUPERHEATED STEAM 

 MAIN STEAM STOP 



38.8 



Figure 9-12.— Main steam system, destroyer escort. 



that receive their steam supply from auxiliary 

 steam systems on most steam-driven ships. As 

 previously noted, the units are not the same on 

 all ships. Some recent ships use main steam 

 instead of auxiliary steam for the forced draft 

 blowers and for some pumps. On some ships, 

 turbine gland sealing systems receive their 

 steam supply from an auxiliary steam system; 

 on other ships, the source of supply is the aux- 

 iliary exhaust system. In general, an increasing 

 use of electrically driven (rather than turbine 

 driven) auxiliaries has led to the simplification 

 of auxiliary steam systems on recent ships. 



On ships having double-furnace boilers, aux- 

 iliary steam is taken directly from the steam 



drum at steam drum pressure and temperature. 

 Since this steam is not superheated, it does not 

 require desuper heating before it can be used as 

 auxiliary steam. On ships having single-furnace 

 boilers, all steam generated in the boiler goes 

 through the superheater; the steam required for 

 auxiliary steam systems is then desuperheated 

 to some extent. On ships having 600-psi main 

 steam systems, auxiliary steam is desuper- 

 heated so that it is approximately at steam drum 

 temperature (or very slightly above). On ships 

 having 1200-psi main steam systems, the desu- 

 perheated auxiliary steam may still have quite a 

 bit of superheat— that is, it may be at a consider- 

 ably higher temperature than the water and steam 

 in the steam drum. 



207 



