1. An Introduction To Marine Steam Propulsion Plant [Source: US Navy]

3. Four Phases of Steam Cycle
Generation
Expansion
Condensation
Feed

4. GENERATION (Boilers)

5. GENERATION Boiler Steam drum fuel is converted to heat
largest and heaviest part of steam plant
heat is transferred via conduction to water in the metal tubes
some of this water becomes steam
Steam drum
as steam is generated it collects in the upper portion of the boiler
steam collecting in the steam drum is called saturated steam

7. GENERATION Super heater
saturated steam does not contain enough thermal energy to make the turbines operate efficiently
uses heat from the burner section of the boiler to increase the temperature of the steam
superheated steam is also dryer which helps prevent erosion of the turbine blades and main feed pumps

8. GENERATION Economizer improves efficiency in the steam plant
uses thermal energy that would go up the stack to preheat feedwater before the steam drum
nest of tubes located between the generating tubes of the boiler and the stack

9. EXPANSION (Turbines)

10. EXPANSION
Turbines
High pressure/high temperature steam goes from the superheater outlet to the high pressure turbine of the main engine
this is where expansion begins
superheated steam expands in the turbine and is converted to mechanical energy to turn the rotor

11. EXPANSION
energy conversion takes place in two steps in each stage of turbine blades
first the steam passes through the nozzles which increase the steam’s velocity
this kinetic energy is then converted into work by the turbine blades
after steam leaves the HP turbine it still has thermal energy
steam undergoes the same process in the LP turbine

14. CONDENSATION (Condenser, MCP, AEC)

15. CONDENSATION Main Condenser
large sealed container that serves as an indirect-type shell and tube heat exchanger
cool seawater flows through thousands of internal tubes
steam from the exhaust of the LP turbine flows over these tubes and heat is removed from the steam, condensing the steam in to a liquid (Condensate)
The condensing action of the steam creates and maintains a vacuum in the condensers

17. CONDENSATION Main condensate pump
one or two stage centrifugal pump, electrically driven
moves condensate from the hotwell through the main air ejector condenser to the deaerating feed tank
pump is drawing a suction on the water in the hotwell
lowest pressure in the system occurs here

19. CONDENSATION Air ejector condenser shell and tube heat exchanger
two functions
removes latent heat from the auxiliary steam being discharged by the air ejector
transfers heat from the steam to the condensate to preheat it before it enters the deaerating feed tank

20. FEED (DFT, MFBP, MFP)

21. FEED PHASE The Deaerating feed tank is the beginning of the feed phase
Direct type heat exchanger - three functions
feed is heated by auxiliary steam and then falls to the lower section - causing the oxygen held in solution to be removed
heats feed and maintains proper temperature of water
storage tank for heated oxygen free feedwater

22. FEED PHASE
Feedwater goes from deaerating tank to main feed boost pump(MFBP)
MFBP
one or two stage double suction centrifugal pump
installed below the DFT
discharges into the suction side of the main feed pump (MFP)

23. FEED PHASE
MFP
Large Multistage Centrifugal pumps (steam or electrically driven)
delivers feedwater in sufficient amounts and develops enough pressure to force the water into the boiler against the pressure of the steam drum

25. MACHINERY PLANT LAYOUT
No two ships are exactly alike
Machinery is arranged in various ways as space and weight permit
Generally speaking
Propulsion machinery is usually on two levels
condensers and main reduction gear on lower level
propulsion turbines and pinion gears are on upper level

26. MACHINERY PLANT LAYOUT
Low pressure turbine exhaust is directly above the condenser
Boilers are on the lower and upper levels along the centerline of the ship
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