PRINCIPLES OF NAVAL ENGINEERING 



RECIRCULATING f ^MAKEUP FEED ' ' AIR EJECTOR* 

 CONNECTION CONNECTION SUCTION 



CIRCULATING- 

 WATER OUTL 



EXHAUST STEAM I 



FROM PROPULSION C 



TURBINES ■! 



ABSOLUTE 

 PRESSURE GAGE 



VACUUM GAGE 

 CONNECTION 



CONDENSATE 

 OUTLET 



47.70X 



Figure 13-1.— Cutaway view of main condenser. 



under the tube bundle is condensed by the con- 

 densate dripping from the condenser tubes. In 

 this process, the condensate (which has been 

 subcooled by its contact with the cold tubes) tends 

 to become reheated to a temperature which ap- 

 proaches the condensing temperature corre- 

 sponding to the vacuum maintained in the hot well. 

 The difference between the temperature of the 

 condensate discharge and the condensing tem- 

 perature corresponding to the vacuum maintained 

 at the exhaust steam inlet to the condenser is 

 called the condensate depression . One measure 

 of the efficiency of design and operation of any 

 condenser is its ability to maintain the conden- 

 sate depression at a reasonably low value under 

 all normal conditions of operation. Excessive 

 condensate depression decreases the operating 

 efficiency of the plant because the subcooled con- 



densate must be reheated in the feed system, with 

 a consequent expenditure of steam. Excessive 

 condensate depression also allows an increased 

 absorption of air by the condensate, and this air 

 must be removed in order to prevent oxygen cor- 

 rosion of piping and boilers. 



Main condensers have various internal baffle 

 arrangements for the purpose of separating air 

 and steam so that the air ejectors will not be 

 overloaded by having to pump large quantities of 

 steam along with the air. Air cooling sections 

 and air baffles may be seen in figure 13-3. 



In some installations the condenser is hung 

 from the low pressure turbine in such a way that 

 the turbine supports the condenser. Where this 

 type of installation is used, sway braces are used 

 to connect the lower part of the condenser shell 

 with the ship's structure. Spring supports are 



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