Chapter 9-MACHINERY ARRANGEMENT AND PLANT LAYOUT 



The reducing station that reduces steam from 

 600 to 150 psig in the engineroom supplies 

 steam at 150 psig and 610° F to the main and 

 auxiliary air ejectors, the distilling plant air 

 ejectors, and the turbine gland seal systems. 

 Line desuperheaters are not installed in the 

 150-psi system in the engineroom. 



In the No. 2 engineroom, a reducing station 

 reduces steam pressure from 150 psig to 100 

 psig and supplies steam at 100 psig and 385° F 

 to the ship's laundry and tailor shop equipment. 

 This 100-psi auxiliary steam system is called 

 the 100-psi constant service system. 



The 150-psi system also supplies two50-psi 

 systems— one a constant service system, one an 

 intermittent service system. Both of these sys- 

 tems are shown in figure 9-18. 



AUXILIARY EXHAUST SYSTEMS 



The auxiliary exhaust system receives ex- 

 haust steam from pumps, forced draft blowers, 



and other auxiliaries which do not exhaust di- 

 rectly to a condenser. Auxiliary exhaust steam 

 is used in various units, including deaerating 

 feed tanks, distilling plants, and (on many ships) 

 turbine gland seal systems. 



The pressure in the auxiliary exhaust system 

 is maintained at about 15 psig. If the pressure 

 becomes too high, automatic unloading valves 

 (dumping valves) allow the excess steam to go 

 to the main or auxiliary condensers; in the 

 event of failure of these unloading valves, relief 

 valves allow the steam to escape to atmosphere. 

 If the pressure in the auxiliary exhaust system 

 drops too low, makeup steam is supplied from 

 an auxiliary steam system (usually the 150-psi 

 system) through augmenting valves. 



The auxiliary exhaust system must be clearly 

 distinguished from the various auxiliary steam 

 systems. Even though the auxiliary exhaust 

 system is a steam system, it is not considered 

 an auxiliary steam system. A reexamination of 

 figure 9-1 may be helpful at this point to clarify 



#2 ENGINEROOM 



#2 FIREROOM 



#1 ENGINEROOM 



#1 FIREROOM 



O DECK OPERATED VALVE 



147.76 



Figure 9-14.— Main steam system, DD 445 and DD 692 classes. 



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