Main Steam CycleIntroductionParts of Main Steam CycleSlide 4BackgroundRankine CycleGeneration Phase - ConventionalBoiler and SuperheaterGeneration Phase - NuclearReactor PlantExpansion PhasePowerPoint PresentationCondensationSlide 14Main CondenserFeed PhaseDeaerating Feed TankPutting It All TogetherYour DrawingQuestions?Main Steam Main Steam CycleCycleLet the fun begin…IntroductionIntroduction•Parts of the Main Steam Cycle•Four Phases of the cycle•Definitions of each phase•Components involved with phases•Press-temp relationshipsParts of Main Steam Parts of Main Steam CycleCycle•Steam Generator (nuclear) or Boiler (conventional)•Turbines•Condenser•Main Condensate Pumps•Deaerating Feed Tank / Reserve Feed Tanks•Main Feed PumpsMain Steam CycleMain Steam CycleBackgroundBackground•Cycle used is a Rankine cycle•P-v and T-s Diagrams•Trace the points of cycle•Provide graphical understanding of cycle•Four phases of cycle•Conventional vs. NuclearRankine CycleRankine Cycle1-2: Feed Phase (Q=0, S=0), Win 2-3: Generation Phase (P=0), Qin3-4: Expansion Phase (Q=0, S=0), Wout4-1: Condensation Phase (P=0), QoutT-s Diagram P-v DiagramGeneration Phase - Generation Phase - ConventionalConventional•Boiler (1200 # steam)•Fuel burned to produce heat -> transferred to water which boils to steam•Steam collects in steam drum (saturated)•Superheater•Increase temp of steam and dries steam•Three reasons for superheating?•Minimize erosion (dry steam better for blading)•Minimize corrosion (less chemicals entrained)•Maximize T (Carnot efficiency)Boiler and SuperheaterBoiler and SuperheaterGeneration Phase - Generation Phase - NuclearNuclear•Reactor (Rx) Plant•Fission in Rx core transforms nuclear energy to thermal energy•Steam Generator•Water Space•U-tubes•Steam Space•Moisture SeparatorsReactor PlantReactor PlantExpansion PhaseExpansion Phase•Steam travels down main steam piping•Turbines convert thermal energy -> mechanical energy (nozzles) and then work (blading) -> turn rotor/shaft•Pressure drops as steam goes through•Work performed on turbine blading•Main Engines (ME) -> propulsion•Ship’s Service Turbine Generators (SSTG) -> electricityCondensationCondensation•Vacuum 26-29” Hg•Air Ejectors - use 150# steam to establish initial vacuum and remove air •Maintained by condensation •volume of water << volume of steam -> contraction•Why vacuum?•Ease of steam recovery (“pulls” steam into MC)•More work out of turbines (larger P and T)•Ease of conversion to waterCondensationCondensation•Main Condenser•Large, indirect, cross-flow, shell-and-tube HX•Seawater used to condense steam •Hotwell - holding area for condensate water at 80-100 F (lowest temp in cycle)•Main Condensate Pumps - send condensate to the DFT at 20-30 psi (suction side is lowest pressure in cycle)Main CondenserMain CondenserFeed PhaseFeed Phase•Deaerating Feed Tank (DFT)•Direct-type HX (Aux Steam used)•Purposes •preheats feed •storage/surge volume•removes dissolved oxygen to minimize corrosion•FYI: RFT’s often used instead•Main Feed Pump•Supplies feed water to Steam Generator (must be high pressure to overcome pressure)Deaerating Feed TankDeaerating Feed TankPutting It All TogetherPutting It All TogetherYour DrawingYour Drawing•Boiler/Steam Generator•Superheater•Turbine•Condenser•Main Condensate Pumps•Main Feed