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ENGINEERING LESSON GUIDE 6

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INTRODUCTION TO NAVAL ENGINEERING MAIN FEED and CONDENSATE Factors Involved in Machinery Plant Layout and Design Midships location of engine rooms and machinery rooms ... – PowerPoint PPT presentation

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Title: ENGINEERING LESSON GUIDE 6


1
INTRODUCTION TO NAVAL ENGINEERING
MAIN FEED and CONDENSATE
2
Main Condensate System
3
P-V DIAGRAM
BOILER
PRESSURE
PUMP
TURBINE
CONDENSER
VOLUME
4
P-V DIAGRAM
SUBCOOLED LIQUID
PRESSURE
SUPERHEATED STEAM
WET VAPOR
VOLUME
5
T-S DIAGRAM
TEMPERATURE
ENTROPY
6
EXPANSION (Turbines)
7
The Expansion Phase
  • Transformations of thermal energy to mechanical
    kinetic energy (at nozzles) to mechanical work
    (at blades)
  • General differences between HP and LP turbines
  • Pressure-temperature relationships throughout
    turbines

8
EXPANSION (Turbines)
  • Goes first to the High Pressure Turbines
  • Converts thermal energy to mechanical energy
  • Steam first goes through nozzles to increase
    steam speed then through blades which does the
    actual work
  • Then goes through Low Pressure Turbine

9
EXPANSION (Turbines)
10
Objectives
  • Components of Main Condensate System and purposes
    of each
  • Components of Main Feed System and purposes of
    each
  • Operation of Automatic Control Systems
  • Interrelationship of systems during operations

11
CONDENSATION (Condenser, MCP, AEC)
12
THE CONDENSATION PHASE
  • Condense steam to water for re-use in plant
  • Why a vacuum?
  • Pump condensate from main condenser to DFT
  • Provide cooling for air ejector condenser

13
SEAWATER COOLING
  • Main Seawater Circulating System
  • Main Seawater Circulating Pump
  • propeller type (high flow rate low HP)
  • used when
  • going astern or stopped
  • slow ahead (lt 5 knots)
  • also to de-water engineroom in case of flooding
  • Scoop Injection System
  • used when moving ahead at speeds over 5 kts

14
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15
CONDENSATE DEPRESSION
  • The difference between temperature of the
    condensate and the temperature at which steam
    condenses at a given vacuum (i.e. sub cooling)
  • Maintained at 2-5 degrees
  • Above 2 Necessary to prevent cavitation and
    vapor lock of the MCP
  • Below 5 Above which efficiency is lost since
    condensate must be reheated. Also, above 5F, the
    absorption of air by the condensate is increased
    which increases the corrosion of piping

16
Main Feed System
  • Purpose to deaerate, preheat, store, and
    transport water from DFT to the boiler or S/G

17
THE FEED PHASE
  • Overall purposes for the feed phase
  • preheat
  • store
  • deaerate
  • increase pressure to deliver feedwater to the
    steam drum
  • Pressure-temperature relationships across each
    component

18
PURPOSE OF DFT
  • Preheats feedwater
  • Deaerates feedwater
  • Stores

19
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20
FEED (DFT, MFBP, MFP)
  • Deaerating Feed Tank
  • Removes Oxygen
  • Preheats
  • Stores Water
  • MFBP takes suction on DFT and discharges it at
    80-100s (Prevents hot feedwater at 250F from
    flashing to steam in the MFP)

21
PURPOSE OF MFBP
  • Prevent vapor lock of MFP
  • Ensure there is always sufficient NPSH for the
    MFP
  • (Typically a single-stage, double-suction,
    centrifugal pump)

22
MAIN FEED PUMP
  • Provides water to the boilers at a sufficient
    rate and pressure to ensure boiler level is
    maintained
  • Typically Multistage, high speed, centrifugal
    pump. May be either steam or electric driven
  • Discharge pressure up to 1300 psig

23
FEEDWATER CONTROL VALVE
  • Regulates the amount of water sent to the boilers

24
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25
AUTOMATIC BOILER CONTROL SYSTEM
  • Three Parts

26
Automatic Combustion Control (ACC) System
27
AUTOMATIC COMBUSTION CONTROL (ACC)
  • Purpose To maintain the boiler steam-drum
    pressure at a constant 1275 psig during steady
    and changing steam conditions.
  • Measures
  • Compares
  • Computes
  • Corrects

28
FEEDWATER CONTROLS (FWC)
  • Purpose To regulate the supply of feedwater sent
    to the boiler for use in steam production
  • Measures
  • Compares
  • Computers
  • Corrects

29
MFP DIFFERENTIAL PRESSURE CONTROLS
  • Purpose Ensures that the feedwater-supply
    pressure is maintained at a constant value above
    the steam-drum pressure (75 psi)
  • Measures
  • Compares
  • Computes
  • Corrects

30
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31
Interrelation of Systems
  • Answering AA2/3 -gt OOD orders AAII
  • Open throttles -gt steam flow -gt steam pressure
  • ACC system air fuel to combustion rate
  • FWC system feed to match steam flow
  • DCS of MFP speed of MFP to discharge
    pressure

32
BOILER WATER CHEMISTRY
33
BOILER WATER CHEMISTRY
  • pH AND PHOSPHATES
  • PREVENTION OF SCALE BUILDUP
  • PURPOSE OF BLOWDOWNS
  • LOWER PH / PHOSPHATE LEVEL
  • REMOVE SLUDGE OR SUSPENDED SOLIDS
  • REMOVE CHLORIDE IONS (FROM SEAWATER ACCIDENT)
  • INSPECTION / CLEANING REQUIREMENTS

34
Factors Involved in Machinery Plant Layout and
Design
  • Midships location of engine rooms and machinery
    rooms

35
Factors Involved in Machinery Plant Layout and
Design
  • Functional relationships between components

36
Factors Involved in Machinery Plant Layout and
Design
  • Use of multiple levels or decks

37
Factors Involved in Machinery Plant Layout and
Design
  • Component relationship to centerline (stability)

38
Factors Involved in Machinery Plant Layout and
Design
  • Ease of maintenance
  • Damage control (prevent spread of fires and
    flooding)
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