PRINCIPLES OF NAVAL ENGINEERING 



Most ships that have 600-psi main steam 

 systems have a 600-psi auxiliary steam system 

 and a 150-psi auxiliary steam system, plus 

 some lower pressure service systems. The 

 600-psi auxiliary steam system serves some 

 machinery directly and also supplies the 150-psi 

 system through reducing valves or reducing 

 stations. The 150-psi auxiliary steam system 

 serves some units directly and also provides 

 auxiliary steam for units or systems that re- 

 quire auxiliary steam at even lower pressures. 



Figure 9-16 shows part of a 600-psi auxiliary 

 steam system for the two forward plants (No. 1 

 and No. 4) on a heavy cruiser of the CA 139 

 class. Note that the system is arranged in 

 loop form, with cross connections at required 

 intervals and with branch lines serving the 

 various units and systems. Note, also, that 

 the auxiliary steam system is, like the main 

 steam system, basically rather simple. 



Ships that havea 1200-psi main steam system 

 have a 1200-psi auxiliary steam system, a 

 600-psi auxiliary steam system, a 150-psi 

 auxiliary steam system, and several constant 

 and intermittent steam service systems. The 

 auxiliary steam systems of the DLG 14 and 

 DLG 15 are described here in some detail as 

 examples of auxiliary steam systems on ships 

 having 1200-psi main steam systems. 



The 1200-psi and the 600-psi auxiliary steam 

 systems for the forward plant of the DLG 14 

 and DLG 15 are shown in figure 9- 17. A similar 

 arrangement exists in the after plant. The 

 1200-psi auxiliary steam system for each plant 

 is entirely separate and independent; the 600- 

 psi systems can be cross-connected but are 

 not normally operated that way. Each plant has 

 two boilers, both of which supply steam to the 

 1200-psi auxiliary steam system of that plant. 

 The steam comes from the desuperheater out- 

 let of each boiler; it is desuperheated from 

 approximately 950° F (the operating temperature 

 at the superheater outlet) to approximately 

 700° F. Note that the steam in this auxiliary 

 steam system still has something more than 

 200° F of superheat, so it is not strictly 

 "saturated" steam. The 1200-psi auxiliary 

 steam lines from each boiler are interconnected 

 so that either boiler can provide steam for 

 everjrthing served by this system. 



The 1200-psi auxiliary steam system sup- 

 plies steam directly to the soot blowers, the 

 forced draft blowers, and the reducing stations 

 that reduce the pressure from 1200 to 600 psig; 



it also supplies augmenting steam at 12 psig 

 to the auxiliary exhaust system, when necessary. 



The 600-psi auxiliary steam system supplies 

 steam at 600 psig and approximately 650° F to 

 both fireroom and engineroom equipment. In 

 the fireroom, the 600-psi system supplies 

 steam to the fuel oil service pumps, the main 

 feed booster pump, the fire pump, and the 

 reducing stations that reduce the pressure from 

 600 to 150 psig. In the engineroom, the 600- 

 psi system supplies steam to the standby lube 

 oil service pump, the main condensate pump, 

 the main circulating pump, and a reducing 

 station that reduces the pressure from 600 to 

 150 psig. 



The 150-psi and the 50-psi auxiliary steam 

 systems for the after plant of the DLG 14 and 

 DLG 15 are shown in figure 9-18. The forward 

 plant has similar systems. 



The 150-psi auxiliary steam system in each 

 plant provides all machinery, equipment, and 

 connections which require 150-psi steam. This 

 system also supplies steam to other reduced 

 pressure systems, via reducing stations, and 

 may deliver steam to other ships or receive 

 steam from outside sources through special 

 piping and deck connections. Another function 

 of the 150-psi system is to augment the auxi- 

 liary exhaust system; in fact, this function is 

 normally performed by the 150-psi system, 

 although it may be performed directly by the 

 1200-psi auxiliary steam system when neces- 

 sary. 



Steam for the 150-psi system in the fireroom 

 is supplied from the reducing stations that 

 reduce the pressure from 600 to 150 psig. There 

 are two such stations ineachfireroom. A spray- 

 type desuperheater reduces the temperature 

 of the fireroom 150-psi system to 400° F. Ser- 

 vices and auxiliaries operated from the 150- 

 psi system in the fireroom include superheater 

 protection steam, 5 service steam systems, 

 oil heating systems, boiler casing steam 

 smothering systems, fireroom bilge steam 

 smothering system, bilge and fuel oil tank 

 stripping pumps (in No. 1 fireroom and No. 2 

 engineroom only), steam for burner cleaning 

 service, and hose connections for boiling out 

 boilers. In emergencies, the fireroom 150-psi 

 auxiliary steam system can also supply steam 

 for some units that are normally supplied by 

 the engineroom 150-psi system. 



Superheater protection steam is discussed in chapter 

 10 of this text. 



210 



