Chapter 9-MACHINERY ARRANGEMENT AND PLANT LAYOUT 



STEAM TO 

 AIR EJECTORS 



TO 

 ATMOSPHERE 



VAPOR FROM 

 -TURBINE GLANDS 



H P DRAINS 

 i ♦ » 



MAIN FEEDPUMP 



ECONOMIZER 



®>-^ 



CONDENSATE PUMP 



RESERVE FEEDTANK 



38.16 



Figure 9-20.— Pressure-closed feed system. 



system when necessary. A manually operated 

 makeup feed valve is provided for this purpose. 

 Makeup feed is brought into the condenser by 

 vacuum drag. Another manually operated valve 

 allows excess condensate to be discharged from 

 the condensate line to the reserve feed tanks. 



Practically all naval ships have more than 

 one feed water system, with cross-connecting 

 lines and valves arranged so that the systems 

 may be operated either split-plant or cross- 

 connected. When warming up or securing one 

 plant, it is often necessary to transfer feed wa- 

 ter from one plant to another. For example, it 

 might be necessary to transfer feed water from 

 one plant to another so that one plant will not 

 have to take on cold makeup feed while another 

 plant is discharging hot excess feed. 



Since reserve feed tanks are normally filled 

 by discharge from the distilling plant, it is sel- 

 dom necessary to transfer feed water from one 

 reserve feed tank to another. However, piping 



system arrangements do permit this transfer to 

 be made when necessary. 



In discussing the condensate and feed system, 

 we have not included the auxiliary condenser and 

 its associated equipment. It should be noted that 

 the auxiliary condenser functions in the same way 

 as the main condenser and returns water to the 

 condensate and feed system. The chief difference 

 between main and auxiliary condensers is that 

 main condensers have larger capacity. 



STEAM AND FRESH WATER DRAINS 



Most of the feed water in a shipboard steam 

 plant is recovered so that it can be used over and 

 over again for the generation of steam. As we 

 have seen, steam is condensed in the main and 

 auxiliary condensers and the condensate is re- 

 turned to the feed system. Also, the auxiliary 

 exhaust steam is used in the deaerating feed 

 tank and thus becomes part of the feed system. 



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