PRINCIPLES OF NAVAL ENGINEERING 



CONTML VALVE, 



SfSta^iii 



EXHAUST 



SIGHT now. 



FLEXIBLE COUPLING 



SIGHT FLOWS 



CLEARANCE INDICATOR 



THRUST BEARING 

 ^ .FLEXIBLE COUPLING 



WASTE OIL DRAIN 



AFTER BEARING OIL DRAIN 



PACKING VENT 



CARBON PACKING VENT \ y 



SEALING STEAM LEAKOFF FROM H.P. PACKING 



\SEAUH6 STEAM 

 LEAK-OFF 



STEAM FROM CRUISING TURBINE 



96.10 



Figure 12-26.— High pressure turbine. 



Aboard naval ships, economy measures can- 

 not be carried to extremes, because there are 

 several safety factors that must be considered. 

 Unless proper safety precautions are taken, 

 reliability may be sacrificed; and in the opera- 

 tion of naval ships, reliability is one of the more 

 important factors. In operating an engineering 

 plant as economically as possible, safety factors 

 and good engineering practice must not be over- 

 looked. 



There are several factors that, if given 

 proper consideration, will promote efficient and 

 economical operation of the engineering plant. 

 Some of these factors are: (1) maintaining the 

 designed steam pressure, (2) proper accelera- 

 tion of the main engines, (3) maintaining high 

 condenser vacuum, (4) guarding against exces- 

 sive recirculation of condensate, (5) maintenance 

 of proper insulation and lagging, (6) keeping 

 the consumption of feed water and potable water 



within reasonable limits, (7) conserving elec- 

 trical power, (8) using the correct number of 

 boilers for best efficiency at the required load 

 levels, and (9) maintaining minimum excess 

 combustion air to the boilers. 



Maintaining a constant steam pressure is 

 important to the overall efficiency of the engi- 

 neering plant. Wide or frequent fluctuations in 

 the steam pressure or degree of superheat above 

 or below that for which the machinery is de- 

 signed will result in a considerable loss of 

 economy. Excessively high temperatures will 

 result in severe damage to superheaters, piping, 

 and machinery. 



Proper acceleration and deceleration of the 

 main engines are important factors in the eco- 

 nomical operation of the engineering plant. A 

 fast acceleration will not only interfere with 

 the safe operation of the boilers but will also 

 result in a large waste of fuel oil. The officer 



340 



