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  • THE ABOVE IS A PICTURE OF A MODERN COAL FIRED ELECTRIC UTILITY UNIT. As you can see it is a rather complex interactive system.
  • This page shows our expertise in the Turbine area.
  • This is an overview of the boiler control system, as you can see this basically applies to the modulating control as opposed to the BMS, Data Acquisition, etc. which is a carry over from the past, since many of these are integrated into a single system now. Basically it regulates the modulating control associated with the main process.
  • The front end is displayed, as you can see it is the master for both the boiler and turbine and coordinates their activities.
  • CFE is the application of advanced control to the front end. Its unique features is its predictive control capability which permits controlling the rate of change which takes place. Note no separation between boiler and turbine control.
  • The standard offering permits operation in any one of the four modes listed and provides bumpless transfer between modes. Coordinated - both the boiler and turbine respond together to satisfy the load requirements Turbine Following - the turbine controls throttle pressure and responds based on what the boiler does Boiler Following - the boiler controls throttle pressure based on what the turbine does Manual - the operator controls the boiler and turbine separately Interlocks are included such that the upstream decisions are limited by the mode of control of the downstream devices.
  • The turbine master basically controls MW, but to prevent system instability it recognizes the boiler’s limitations and will not over extend the boiler. This provides fast response with stability.
  • With variable pressure operation the turbine valves are ideally never moved. Throttle pressure is changed to effect a load change. To improve response we move the turbine valves to achieve the new load setting and then return the turbine valves to their desired position. Throttle pressure set point is programmed off of load but trimmed to return the turbine valves to the proper position (normally a valve point). Because this moves thermal stress from the turbine to the boiler, not all boilers can operate in this mode.
  • The boiler master basically sets the firing rate for the boiler. The boiler master can only be placed in automatic if the down stream control loops are in automatic. Boiler runbacks and rundowns are initiated here, the controls are placed in turbine following, and are based on boiler capabilities and not load (MW) values.
  • Fuel control is the next section we will discuss. It basically consists of the Fuel Master and the fuel control, which for the standard is presently CE coal mills.
  • The fuel master determines the amount of fuel that each mill needs to send to the boiler. The fuel demand can not exceed the available air for safe combustion. Mills have coal storage capacity which means that their response isn’t constant, to recognize this a model is incorporated to bring coal flow measurement (typically feeder speed) into line with actual coal flow to the boiler. To properly control fuel flow the fuel BTU value needs to be known, the controls use the boiler as a calorimeter to calculate the coal BTU value.
  • The mill control is the actual regulation of the mill which consists of coal flow to the mill (feeder speed typically) and primary air flow (the air required to transport the coal to the boiler from the pulverizer). The primary air must be at the proper temperature to assure drying of the coal. To prevent plugging of the mill, on either high mill amps or high mill differential the feeder speed is reduced until the problem clears. Proper primary air flow takes precedent over primary air temperature. Our normal offering includes interlocks on the mill which are tied into the burner management system for proper positioning the dampers during mill start/stop and emergency conditions.
  • Air control consists of regulating both the FD and ID fans
  • The FD fans provide the secondary air to the boiler for safe complete combustion of the fuel. Air flow is based on the fuel entering the boiler and trimmed by the flue gas O2 observed. The air flow can not decrease below that calculated as being required for safe combustion of the fuel entering the boiler. The controls include the interlocks for both the inlet and discharge dampers required for fan starting, stopping, and fan idle conditions. The FDs can’t be place into automatic unless an ID fan is already in automatic control, this assures the ability to control furnace pressure.
  • The FD push air into the boiler while the ID fans suck it out, these must be properly balanced if furnace pressure is to be properly controlled. Fluctuating furnace pressure will impact air flow which impacts combustion resulting in (as a minimum) an unstable process and potentially unsafe operation . The controls fully meet the NFPA requirements including triple redundant furnace pressure transmitters, directional blocking, and an MFT kicker. Note that on an MFT the FD fans are placed in manual to hold air flow constant. Like the FD fans damper interlocks are included with our base offering, to start/stop and position as required based on operating conditions.
  • Feedwater control regulates the water input to the boiler.
  • Single element control refers to the fact that drum level is the measurement used to control the flow of feedwater to the boiler. This is used during low loads since flow measurements are inaccurate at these values. Three element is the normal control method it matches feedwater flow to steam flow and uses drum level as a trim. To maintain accuracy the drum level is density compensated, this is important during startup and on variable pressure units.
  • Single element control refers to the fact that drum level is the measurement used to control the flow of feedwater to the boiler. This is used during low loads since flow measurements are inaccurate at these values. Three element is the normal control method it matches feedwater flow to steam flow and uses drum level as a trim. To maintain accuracy the drum level is density compensated, this is important during startup and on variable pressure units.
  • Steam temperature control regulates the final steam temperature of both the main steam and the reheat steam entering the turbine. If this temperature is low, the unit becomes less efficient (there is less energy for the turbine to extract from the steam) while if the temperature is to high damage to the turbine can result.
  • Superheat temperature control refers to controlling the temperature of the main steam, typically at a value of 1005 F. The standard consists of two stage attemperation, that means that spray water is applied twice to the steam as it travels from the drum to the turbine to control steam temperature. Interlocks are included to close valves on MFTs, the block valve is controlled so that it doesn’t needlessly cycle as intermittent spray is required. The controls also include windup protection for when control isn’t possible.
  • Reheat steam is steam which has gone through the high pressure turbine and is returned to the boiler to be reheated before going to the next turbine stage. Reheat is often controlled by adjusting the heat distribution within the furnace thru the use of burner tilts, pass dampers, or gas recirculation based on boiler design. Common to all boiler designs is the use of sprays, which is minimized because it is inefficient. The standard only covers the spray control, we have experience with all other variations . Like the SH spray, integral tracking is provided to prevent windup until spray control is active. And similar to the SH spray interlocks are provided for both the spray and block valves, and the block valves are operated in a manor to prevent unnecessary cycling.
  • Interface to plant LDC sends a MW set point as well as load limits and runbacks over the network.
  • Onboard relay with 2 Form C contacts for wiring 2 out of 3 voting for overspeed tripping at 5 mSec Speed control at 3600 RPM is at 16 mSec
  • ATC continually monitor the following system parameters and alarms. Programs depend on available I/O When not in control it monitors
  • Briefly review then use next slide for explanation Valve indication and testing Turbine in hand Turbine in manual Turbine in auto (remote)
  • Briefly review then use next slide for explanation Valve indication and testing Turbine in hand Turbine in manual Turbine in auto (remote)
  • Briefly review then use next slide for explanation Valve indication and testing Turbine in hand Turbine in manual Turbine in auto (remote)
  • Based on existing flowcharts and constants provided by the customer. If flowcharts do not exists, the customer must request them from the turbine OEM. Generates speed targets, rates and holds (for soaking, etc. ) Generates load rates and holds ATC combined with RSM will automatically accelerate the unit from turning gear to synch speed as well as monitoring the loading rate after the breaker is closed
  • ATC continually monitor the following system parameters and alarms. Programs depend on available I/O When not in control it monitors Up to 10 graphics.
  • Feedwater control regulates the water input to the boiler.
  • Derived from actual I&C architecture diagrams provided by various AEs/EPCs on new coal plant projects
  • Derived from actual I&C architecture diagrams provided by various AEs/EPCs on new coal plant projects
  • Power industry is experiencing a dramatic change in dynamics than any other industry. Deregulation and consolidation has altered the century old business model. Competition between utilities, environmental concerns, and increasing power demand have combined to create a new market reality. There is a strong pressure among the utilities to increase the avilability, reliability and effeciciency of the operating plants Emerson Process Management Power & Water Solutions, Inc. has energized the power industry with revolutionary control solutions for more than 40. We understand the changing dynamics of the industry with our products and solution tailor made for the power industry. Our wide portfolio of solutions can help you achieve your objectives; -Fleet optimization software & enterprise management, Fleet financial performance and emissions, optimizers, Fleet performance monitoring and visualization, Fleet historian and report generator -Enterprise-wide systems integration -Fleet-wide asset management and reliability programs Plant Optimization Software including Plant financial performance, boiler efficiency, emissions, steam temperature, and sootblower optimizers Unit Controls and Monitoring Systems -Distributed control for burner management, boiler, turbine, fuel handling, balance of plant, emissions control, etc. -Smart instrumentation and bus technologies (HART, FOUNDATION™ fieldbus, PROFIBUS DP, DeviceNet, etc.) Our power resume includes: Convention furnace operations with drum, once through, and fluidized bed boiler types, Over 1000 steam and gas turbine control systems, including retrofits to General Electric, ABB, Westinghouse, and Siemens machines , Hundreds of combined cycle, cogeneration, and district heating plants Hydro electric plants around the world use our systems for control and fleet management including:
  • Emerson Power plant applications

    1. 1. Power Plant ApplicationsPower Plant ApplicationsNigam SharmaNigam SharmaSr. Regional Manager, Asia PacificSr. Regional Manager, Asia Pacific
    2. 2. AgendaAgenda Power Plants Over View Main Components of a Power Plant Typical Controls Applications
    3. 3. Types of PlantsTypes of Plants Thermal Power Plants Coal Fired Utility Oil and Gas Fired Plants Bio-fuel Plants Gas Turbine Plants Gas and Oil Fired Simple Cycle Gas Turbine Plants Combined Cycle HRSG and Steam Turbine Plants (CCP) Cogeneration Plants (Industrial or District Heating) Oil & Gas Fired CCP Bio-Fuel CFB plants Nuclear Plants√√√√√√XX
    4. 4. Thermal Plant OverviewThermal Plant Overview1. Cooling Tower 2. Cooling Water Pump 3. 3-phase Transmission Line4. Unit Transformer 5. 3-phase Electric Generator 6. Low Pressure Turbine7. Boiler Feed Pump 8. Condensor 9. Intermediate Pressure Turbine10. Steam governor valve 11. High Pressure Turbine 12. Deaerator13. Feed Water Heater 14. Coal Conveyor 15. Coal Hopper16. Pulverised Fuel Mill 17. Boiler Drum 18. Ash Hopper19. Superheater 20. Forced Draught Fan 21. Reheater22. Air Intake 23. Economiser 24. Air Preheater25. Electrostatic Precipitator 26. Induced Draught Fan 27. Chimney Stack
    5. 5.  Boilers or Steam Generators Generate steam at desired rate, pressure and temperature byburning fuel in its furnace. The boiler is that part of the steam generator where phase change(or boiling) occurs from liquid (water) to vapour (steam), essentiallyat constant pressure and temperature. Steam Turbine Steam turbine is a mechanical device that extracts thermal energyfrom pressurized steam, and converts it into useful kinetic(rotational) energy which rotates the steam turbine. Most steam turbines rotate at 3000 rpm or 3600 rpm. Electric Generator Electrical generator is a device that converts kinetic energy toelectrical energy, generally using electromagnetic induction. Electric Generators are rotated by Steam Turbines at 3000 rpm or3600 rpmMajor ComponentsMajor Components
    6. 6. BottomAshSystemEconomizerHoppersF DFanGeneralWaterSumpBOTTOMASHHOPPERSettlingPondWATERTREATMENTCoalBunkerConveyorsPulverizersLoadGen.HP IP L PTurbineEcon-omizerRe-HeatSuperHeaterDRUMCondenserP AFanIDFansHPFWHtrLPFWHtrAshTransferWaterClean-upPrecipitatorsStackGasScrubberEmissionsMonitorFlyashCond.PumpBFPDeaeratorCoolingWaterFeederDowncomersRisersAir HeaterPower Plant Process MapPower Plant Process MapWater Vapor &Scrubbed Gases
    7. 7. Basic Boiler TypesBasic Boiler Types Up to an operating pressure of around 190Kg Bar in theevaporator part of the boiler, the cycle is Sub-Critical. In this casea drum-type boiler is used because the steam needs to beseparated from water in the drum of the boiler before it issuperheated and led into the turbine. Above an operating pressure of 220Kg Bar in the evaporator partof the Boiler, the cycle is Supercritical. The cycle medium is asingle phase fluid with homogeneous properties and there is noneed to separate steam from water in a drum. Drumless or Once-through boilers are therefore used in supercritical cycles. Advanced Steel types must be used in Supercritical boilers forcomponents such as the boiler and the live steam and hot reheatsteam piping that are in direct contact with steam under elevatedconditions Sub-critical Boilers: Steam conditions up to 220Kg bas/ 540°Care achieved Supercritical Boilers: Steam conditions up to 300 KgBar/600°C/620°C are achieved using steels with 12 % chromiumcontent.
    8. 8. Supercritical Once Through Power PlantSupercritical Once Through Power Plant Power Generation Cycle Efficiency primarily depends on thetemperature difference across steam turbine. Higher boiler outlet temperature results in higher difference. Higher steam temperatures is also linked to increased pressuresto keep the steam volume within manageable limits. At pressures in excess of 220Kg bar, the fluid is termedsupercritical. The increased pressure also increases cycle efficiency and,although this increase is a second-order effect compared with theeffect of temperature, but it can still make an importantcontribution to increasing overall plant efficiency. “SupercriticalSupercritical" is a thermodynamic expression describing thestate of a substance where there is no clear distinction betweenthe liquid and the gaseous phase (i.e. they are a homogenousfluid). Water reaches this state at a pressure above around 220Kg Bar.
    9. 9. Supercritical Once Through Power PlantSupercritical Once Through Power Plant Supercritical coal fired power plants have higher efficienciesof almost 45% Supercritical Power plants have lower emissions than sub-critical plants at any given power output.
    10. 10. Various Boiler TypesVarious Boiler Types
    11. 11. HPFWHTRLPFWHTRHP L PSecondarySuperHeaterPower Plant ProcessPower Plant ProcessMapMapOnce-Thru BoilerBFPWater Vapor &Scrubbed GasesLoadGen.TurbineEcon-omizerRe-HeatCondenserIDFanPrecipitatorsStackGasScrubberEmissionsMonitorFlyashDeaeratorCoolingWaterBottomAshSystemEconomizerHoppersF DFanSettlingPondAshTransferWaterClean-upCond.PumpGeneralWaterSumpCoalBunkerConveyorsPulverizersP AFanFeederPrimarySuperHeaterIPAir HeaterBOTTOMASHHOPPER
    12. 12. Circulating Fluidized Bed BoilersCirculating Fluidized Bed Boilers A bed of sand, ash and fuel particlesis fluidized by the combustion air,which is blown into the bed throughthe bottom. Due to high air/flue gas velocity thefuel is carried over in the combustiongases. The solid material is then separated ina cyclone and recycled to the lowersection of the bed. CFB combustion process is ideallysuited to burning low-quality fuels, fuels with a high moisture content waste-type fuels. All coals, lignite, petroleum coke,biomass, waste coal, refuse-derivedfuels, agricultural and pulping waste,and municipal solid waste
    13. 13. Typical Large Steam TurbineTypical Large Steam Turbine Steam turbine is a mechanical device that extracts thermal energy frompressurized steam, and converts it into useful kinetic (rotational)energy by expansion. The expansion takes place through a series of fixed blades (nozzles)and moving blades. The moving blades rotate on the turbine rotor and the fixed blades areconcentrically arranged within the circular turbine casing which issubstantially designed to withstand the steam pressure. Most steam turbines rotate at 3000 rpm or 3600 rpm.
    14. 14. Basic Steam TurbinesBasic Steam Turbines The Turbine designs for a Supercritical plant are similar to thesub-critical except that special materials required for the casingsand walls for withstanding high Temperatures and pressures inSupercritical Steam Turbines. High Pressure (HP) Turbine: In order to cater for the highersteam parameters in supercritical cycles, materials with anelevated chromium content which yield higher material strengthare selected. Intermediate Pressure (IP) Turbine Section: In supercriticalcycles there is a trend to increase the temperature of the reheatsteam that enters the IP turbine section in order to raise thecycle efficiency. As long as the reheat temperature is kept at560 DEGC there is not much difference in the IP section of Subcritical and Super Critical plants. Low Pressure (LP) Turbine Section: The LP turbine sectionsin supercritical plants are not different from those in subcriticalplants.
    15. 15. Combined Cycle PlantsCombined Cycle Plants Term Combined Cycle is used to describe process that usescombination of more than one thermodynamic cycles. Combined Cycle Power Plant (CCPP) means a combination ofgas turbine generator (Brayton cycle) with turbine exhaustwaste heat boiler and steam turbine generator (Rankine cycle)for the production of electric power. CCPP Common Combinations One CT and One Steam Turbine (1 on 1) Two CTs and One Steam Turbine (2 on 1) X CTs and Y STs (X on Y) CTs always paired with a HRSG 2 on 1 common - all generators work out to be comparable size
    16. 16. Simple Cycle Combustion (Gas) TurbineSimple Cycle Combustion (Gas) TurbineThermal Efficiency = 35-40%35-40% ElectricityGenerator3% Aux. Power + LossesAir100% FuelCombusterStack57-62%Compressor Turbine
    17. 17. Combined Cycle Power GenerationCombined Cycle Power GenerationThermal Efficiency = 45-55%35-40% ElectricityGenerator6% Aux. Power + LossesAir100% FuelCombusterStack20%Compressor Turbine28%Steam CondenserHRSGSteamSupplementaryFuel (Optional)ExhaustGasSteam TurbineGenerator12-15% ElectricityLake
    18. 18. Typical Combined Cycle PlantTypical Combined Cycle PlantGas Supply StationGas Supply Gas Turbine StackHeat Recovery Steam GeneratorHRSG StackGeneratorTransformerTransmissionDeaeratorBoiler Feed PumpCoolingTowersCondensateExtraction PumpGeneratorTransformer TransmissionGas TurbineIP LP GeneratorCooling WaterSwitch YardDemineralization PlantRaw WaterFWFWSwitch YardAir IntakeCondenserBypassDamper
    19. 19. Most Common Combined CycleMost Common Combined Cycle– 2 on 1 Process– 2 on 1 ProcessAirAirGTGTHRSGHRSGSTGenGenGenSteamSteamStack GasStack GasLegendGT – Gas Turbine Gen - GeneratorST – Steam Turbine HRSG – Heat Recovery Steam Generator
    20. 20. Common Cogeneration PlantsCommon Cogeneration Plants Cogeneration is the simultaneous production of power/electricity,hot water, and/or steam from one fuel. Cogeneration plants can reach system efficiencies exceeding 80% Industrial Plants Multi utility plants; Electricity, Process Steam, Heating Steam, Hotwater, Chillers etc. District Heating Plants Extraction steam for residential heating Oil or Gas fired Combined Cycle Cogen Conventional Boilers Cogen Circulating Fluidized Bed BoilersLow Calorific Value, high moisture, low Sulphur fuelsBagasse, Rice husk, Rice Straw, Wood Chips etc
    21. 21. Industrial Co-GenerationIndustrial Co-GenerationBagasseRice HuskRice StrawWood ChipsEtc.Thermal Efficiency = 80%
    22. 22. District HeatingDistrict Heating15%SteamStackAir15% ElectricityBoiler Steam Turbine Generator5% Aux. Power + LossesHeatExchanger55%SteamCondenser10% LossesFeedwaterLoopThermal Efficiency = 70%
    23. 23. Power Plants ControlsPower Plants ControlsCapabilityCapability
    24. 24. Typical Boiler Plant Control FunctionsTypical Boiler Plant Control Functions Fuel Management Fuel control Mill control Burner Safety & control Air Management Fans Control Steam temperature Management SH Steam Temp Control RH Steam Tem Control Feed Water Management Boiler Drum Level Control Deaerator Level Control Soot Blower Controls Emission Management
    25. 25. Typical Steam Turbine Control FunctionsTypical Steam Turbine Control Functions Speed loop Control MW loop Control Speed or MW demand and rateselections Initial MW pickup 1st stage pressure loop Load limiting Inlet pressure limiting(adjustable) Fail safe turbine trip design Valve testing & Valvecalibration Individual valve curves Critical Overspeed detection &protection Hotwell Level & Condensateextraction Controls HP & LP Bypass Controls HP & LP Heater level CascadeControls Gland steam Press control Turbine Stress Calculations Turning Gear Controls Main Oil, Safety Oil Pumps Control Seal Oil Pumps Extraction controls
    26. 26. Typical CCPP Control FunctionsTypical CCPP Control Functions HRSG (Heat Recovery Steam Generator) Boiler Controls Un-fired HRSGBypass Damper ControlFeedwater - Drum Level ControlLive Steam Temperature ControlTurbine Bypass ControlDeaerator Level ControlHotwell Level ControlAdvanced Controls Fired HRSG (additional controls)Fuel ControlsAir ControlBurner ManagementTemperature Control Gas Turbine Controls In most cases GT controls are supplied by OEM
    27. 27. Typical Balance of Plant ControlsTypical Balance of Plant Controls Balance of Plant Controls (Miscellaneous Controls) Water Treatment Plant Controls Circulating Water System Raw Water system Turbine Cooling Oil Temperature Controls Generator Cooling Oil Temperature Controls Ash Handling System Controls Fuel Handling SystemsFuel Skid Controls (CCPP)Coal Handling System Controls Environmental ControlsFlue Gas De-Sulphurization ControlsScrubber Controls Motor Controls Electrical Controls & Monitoring
    28. 28. Basic level: Single drive control with electrical protections, auto/manual modes Single loop control with protection of actuators, auto/manual modes Interlocks between the control loops and drivesControl of technological groups for Boiler and Turbine: Coordinated loops control (common setpoint, interactions) Cross interlock feedbacks and priorities Sequences Turbine start-up, roll-off, and other turbine coordinated controls Burner Management SystemCoordinated Unit Control: LDC - Load Demand Computer - selection of boiler / turbine modes Unit remote control from Dispatch Center Main unit control sequences Run-backs & Run-upsConcept of a Unit ControlConcept of a Unit Control
    29. 29. Binary ControlDrive Control Standards for: low voltage motors high voltage motors open/close valves or dampers electrical actuatorsSequential ControlFeatures of a sequence: consists of a sequence head and sequence steps sets time relations between performed steps allows start, stop and resume by operator incorporates emergency logic and procedures incorporates interaction logic and operator’s permissivesConcept of a Unit ControlConcept of a Unit Control
    30. 30. Modulating Control Control Structures: Basic level - single loop executing a direct control of actuator Cascade level calculating setpoint for basic level loop Coordinating level responsible for unit load and cross feedbacksbetween parts of the unit Supervisory optimization structure, which calculates corrections forother control loops, based on feed-forward and Smith predictionphilosophy Control Algorithms: Mathematical algorithms Universal PID type (PID, PIDFF) Dedicated for power applications: Smith predictor, drum levelcorrection, steam table, PID with variable parameters Value tracking for bumpless transfer during auto / manual switch Advanced algorithmsConcept of a Unit ControlConcept of a Unit Control
    31. 31. Coordinated Unit ControlsCoordinated Unit Controls
    32. 32. Coordinated Unit ControlsCoordinated Unit ControlsADSInterfaceUnitMasterBoilerMasterFuelMasterAirSteamTemp FeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnace DraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad Demand
    33. 33. Front EndFront End SystemFront End SystemADSInterfaceUnitMasterBoilerMasterFuelMasterAirSteamTemp FeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnace DraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad Demand
    34. 34. ADSInterfaceFuelMasterAirSteamTempFeedwaterBoilerTurbineFront EndMill 1 Mill nIDFansFDFansFurnace DraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad DemandLoad Demand Computer(LDC)Load Demand ComputerLoad Demand Computer
    35. 35.  Invented by Westinghouse for coordinated unit control Allows to control a unit in different modes of operation: Turbine Follow Mode: Turbine control with throttle pressure –The turbine follows the boiler load, LDC tracks the actual unit load andcalculates setpoint for the boiler (MW loop is not in use) Boiler Follow Mode: Boiler control with live steam pressure –The boiler adapts the steam generation to the consumption required bythe turbine, LDC tracks the actual unit load and calculates the setpointfor turbine valve position (MW loop is not in use) Coordinated Control Mode:Either turbine or boiler controls live steam pressure and boiler or turbinerespectively (MW loop is in use for turbine or boiler)Load Demand ComputerLoad Demand Computer
    36. 36.  LDC is a software model of the process, which calculateson-line all required control setpoints using “feed-forward” Operator sets the required load or MW demand LDC calculates the main setpoints separately for the boilerand the turbine control structures The structure for boiler recalculates setpoints for loopscontrolling air and fuel Tunable function generator algorithms calculate setpoints forloops controlling the actuators LDC allows to keep unit in automatic control also duringrunbacks or tripsLoad Demand ComputerLoad Demand Computer
    37. 37.  Four Modes Coordinated Turbine Follow Boiler Follow Manual (separated) Bumpless transfer between all modes Interlocks prevent Unit Master from controlling unless eitherBoiler or Turbine Master in Auto Rate limiting on ramped signalsLoad Demand ComputerLoad Demand Computer
    38. 38.  Turbine Master (Fixed Pressure) regulates turbine to satisfy megawatt demand Recognizes boiler’s response capabilitiesTurbine MasterTurbine Master
    39. 39.  Turbine Master (Variable or Sliding Pressure) Alternative to fixed pressure mode Throttle pressure varied with load while turbine valvesremain in fixed position Valves allowed to move on load changes for fastresponse Throttle pressure allowed to vary to maintain propervalve position Not suitable for all boilersTurbine MasterTurbine Master
    40. 40.  Boiler Master Sets boiler firing rate Interlocked to lower control loops Dynamic control to improve responsiveness Runbacks and rundowns based on boiler capabilitiesBoiler MasterBoiler Master
    41. 41. ADSInterfaceLDCBoilerMasterFuelMasterAirSteamTempFeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnaceDraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad DemandFuel MasterFuel Master
    42. 42. FuelFuelMasterMaster Fuel Master Develops base control signal for coal mills Performs fuel/air cross limiting Incorporates a mill model to improve coal flowmeasurement Uses boiler as calorimeter
    43. 43. FuelFuelMasterMaster Mill Controls Regulates coal flow Regulates primary air flow Regulates coal/air temperature leaving mill Feeder overrides on high mill amps and/or mill differentialpressure Primary air flow takes priority over coal/air temp. Includes interlocks to air dampers for safety and interfaceto BMS
    44. 44. ADSInterfaceLDCBoilerMasterFuelMasterAirSteamTempFeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnaceDraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad Demand
    45. 45. Air FlowAir FlowControlControl FD Fan Control Controls combustion air flow Firing rate sets air flowrequirement Includes damper interlocks Interlocked to ID fans for automode Includes fuel/air cross limiting(O2 trimming)
    46. 46. Air FlowAir FlowControlControl Furnace Draft Control Regulates ID fans to provide proper exhausting force for gas flowthrough boiler Uses FD fan demand as feedforward Utilizes three furnace pressure transmitters (middle-of-three) forcontrol Fully meets NFPA requirements for:Rapid closing of ID inlet dampers on MFTDirectional blocking on low furnace pressure Includes damper interlocks for starting/stopping
    47. 47. ADSInterfaceLDCBoilerMasterFuelMasterAirSteamTempFeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnaceDraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad Demand
    48. 48. FeedwaterFeedwaterControlControl Feedwater Control Regulates feedwater flow andcontrols drum level Two modes of operationSingle element for useduring startupThree element fornormal operation Drum level signals aredensity compensated
    49. 49. Drum levelDrum levelControlControl
    50. 50. ADSInterfaceLDCBoilerMasterFuelMasterAirSteamTempFeedwaterBoiler TurbineTurbineMasterMill 1 Mill nIDFansFDFansFurnaceDraftS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad Demand
    51. 51. SteamSteamTemperatureTemperature Superheat Temperature Control Regulates main steam temperature Standard consists of two stage attemperation Includes integral windup protection Includes interlocks for spray and block valves
    52. 52. SteamSteamTemperatureTemperature Reheat Temperature Control Regulates reheat steam temperature thru the use of sprays &burner tilting arrangement System tracks until spray valve open Interlocks for both spray and block valves included
    53. 53. Furnace 2 ndS.H.PIDPIDPIDPIDXFiring RateBoilerMasterDesired Spray(20%)WW OutletTempLDCOutEconomizerFuel/Air4thS.H.3rdS.H.PIDFW FlowControlFW/FRratioDMCAlgorithmSUMRHTilts/DamperSetpoints2nd, 3rdand 4thSH1stS.H.APC Steam Temperature ControlAPC Steam Temperature ControlSchemeScheme
    54. 54.  A Safety System Permits safe start-up, operation, and shutdown of the boiler Supervises Fuel insertion/withdrawal from boiler conforming toestablished safety standards Monitors and controls igniters and burners Separate Flame Scanners used to detect igniter and main flames Three type of flame scanners Ultraviolet, typically used for natural gas and light oils Infrared, typically used for medium to heavy oils and pulverized coal All Fuels, typically used with gas igniters & coal as main fuel Other Field Devices Safety shut-off valves Pressure, temperature, flow & valve position limit switches Blowers to cool scanners or provide combustion air for ignitersBurner Management SystemBurner Management SystemDefinitionDefinition
    55. 55.  Critical safety signals are wired as redundant I/O for maximum boilersafety. An automatic start sequence ensures correct completion of boiler airpurge and satisfies safety permissives before fuel firing, preventingoperator error. Continued monitoring of boiler conditions actuates a safety shutdown tripif unsafe conditions develop. Operator maintains control capabilities from the operator console orburner front digital logic stations. First-out indications are provided for identification of the cause of boilertrip Automatic Boiler Purge Prior to Restart Flame Detection, Monitoring & protection Master Fuel Trip Burner/Mill Start-Up and Shutdown Sequences Safety Interlocking Alarming of Abnormal ConditionsBurner Management SystemBurner Management System
    56. 56.  6 to 8 Pulverizers (Mills) needed in each boiler to supplyPulverized coal to the burners One mill normally supplies pulverized coal to one burnerlevel. Additional mills supply each additional burner levelon a one-for-one basis. There are between four and eight burners per level. Thisdepends upon the type of furnace, e.g. wall fired,tangential, split furnace, etc. With dual fuel firing, there will also be oil guns /gas nozzleson one or more burner levels. There will be four to eightguns / nozzles per level.Mills, Burners and LevelsMills, Burners and Levels
    57. 57. Burner ArrangementsBurner ArrangementsWall-Fired Tangential Corner-FiredSlagCrushed CoalAir SecondaryFurnacePrimary FurnaceCyclone(B&W Exclusive)
    58. 58. Burner ArrangementsBurner ArrangementsMultipleElevationsTo otherburnersthis elevationDriveMotorPulvorizeror ‘Mill’FeederCoalBunkerAir inBoilerOne of six;one per burnerelevation
    59. 59. The Burner "Front"The Burner "Front"Startup Sequence(Light-off by burner pairs)- Purge air-10 Minutes- Purge air Off- Open Dampers- Ignition Spark ON- Ignition Valve OPEN- Prove Igniter ON- Main Fuel ON- Prove Main Flame ON- All Ignition OFF onCombustion ControlFuelIgnitionTransformerIgniterDamperDamperPurgeAirMain BurnerIgnitionFlameMainFlameIgnitionFlameDet.MainFlameDetCoolingAirWindBox
    60. 60.  Enhanced safety and availability Greater operational flexibility Significant auxiliary fuel savings Continuous safety monitoring Consistent start-up and operation Full integration of all facets of the firing system Integrated Air damper controls Improved plant availability Reduced maintenance costs Prevention of boiler explosion NFPA 8502 code compliance Expandable solutionsOvation BMS FeaturesOvation BMS Features
    61. 61. TurbineMasterBoilerMasterFeedwater CombustionFuelValveFD Fan ID FanPump(Turbine)Pump(Shaft)Pump(Standby)Load DemandComputerHigh LimitLow LimitRamp RateOperatorSet LimitsRunbacksRundownsBlock IncreaseBlock DecreaseContingencyDigitalControlLocalRemoteValvePositionerPassDampersSpraySteamTemp.Steam Turbine ControlsSteam Turbine Controls
    62. 62. Ovation Turbine Control ArchitectureOvation Turbine Control Architecture Redundant systems - Processor - I/O interface - Power supplies - Networkinterface System same as rest of plant Controller hardware and I/O User Interfaces Network Standard I/O cards for specializedturbine applications Speed cards Valve cards
    63. 63. Turbine Control Requires Specialized I/OTurbine Control Requires Specialized I/O Speed Detector Module Valve Positioner Module Servo Driver Module
    64. 64. Speed Detector ModuleSpeed Detector Module 5ms update rate for overspeeddetection Variable update rate for speedregulation Controller-independent speed detectionand tripping using dual on-board formC outputs for fast reaction to overspeed conditions Open-wire detection for low resistancesource less than 5000 Ohms Redundant power feeds 1000V dielectric withstand electricalisolation between logic signal and fieldinputs Hot swap capability
    65. 65.  Self calibrating & Self Diagnostics PI control loop with 10 millisecond loop time Programmable PI gain and integral time constants Normal mode or SLIM interface for local manual operation Up to three redundant servo valve actuator coil drive outputs Supports redundant coil and redundant LVDT capability (Redundant configuration) Interfaces to LVDT interface to primary excitation and dual secondary feedbackwindings 24/48V dc input for emergency valve closure independent of controller 16 bit micro-controller watchdog timer for servo valve actuator coil drive Supports single mode (full arc) or sequential (partial arc) modes of valve operation Watchdog timer for I/O bus Redundant configuration option Redundant 24V power auctioneering Local calibration & tuning capability without trim pots Open-coil and shorted-coil diagnostics Runs seating and back-seating logicValve Positioner ModuleValve Positioner Module
    66. 66.  Self calibrating & Self Diagnostics PI control loop with 10 millisecond loop time Programmable PI gain and integral time constants Normal mode operation only 2 servo valve actuator coil drive outputs Supports redundant coil and dual LVDT capability. 2 DC-LVDT or AC-LVT outputs & 2 DC-LVDT or AC-LVT inputs 16 bit micro-controller Watchdog timer for servo valve actuator coil drive Watchdog timer for I/O bus Redundant feedback option for AC-LVT Redundant 24V power auctioneering Local calibration & tuning capability without trim pots Open-coil and shorted-coil diagnostics Runs seating and back seating logic Hot swap capabilityServo Driver ModuleServo Driver Module
    67. 67.  Main Stop Valves or Throttle Valves, used primarily duringstart-up, machine protection Governor Valves or Control Valves, control the turbine overmost of the operating range Reheat Stop Valve, on-off type valve to backup theintercept valve Intercept Valve, used to prevent steam from enteringturbine after load loss Full Arc Admission / Partial Arc Admission Single Valve Mode / Sequential Valve ModeSteam Turbine Valve TerminologySteam Turbine Valve Terminology
    68. 68. Governor Control FunctionsGovernor Control Functions Control of: Turbine stop valves Control valves Reheat stop valves Intercept valves Monitor & Control of: Speed Main steam pressure Chest pressure 1st stage pressure Reheat pressure Load
    70. 70. 135263512464Main Steam SupplyGovernor/ControlValvesGovernor/ControlValvesThrottle/StopValve 1Throttle/StopValve 2NozzleBlockFull Arc / Single Valve Mode = All Governor/Control Valves opened togetherPartial Arc / Sequential Valve Mode = Governor/Control Valves opened independentlySteam Flow Through Nozzle BlockSteam Flow Through Nozzle Block
    71. 71. Typical Startup and Loading ProgramsTypical Startup and Loading Programs Pre Warm Pre Roll Conditions 1st Stage Shell Metal Temp Change Hot Reheat Temp Change HP allowable Ramp Rate Reheat allowable Ramp Rate 1st Stage Shell Steam Temp Speed Soaks (1000, 3000 and 3600 RPMs) Initial Load Pickup and Soak
    72. 72. Steam Turbine System AuxiliariesSteam Turbine System Auxiliaries Motor Operated Valves Solenoid Operated Valves Vapor Extractors Turning Gear Turbine Drain Valves Jacking Oil Pumps Gland Steam System Seal Steam System Lube Oil System Auxiliary Steam System Emergency Leak-off System Vacuum Breakers Bentley Nevada Modbus Link Turbine Supervisory
    73. 73.  Turbine bypass systems can contribute to flexible plantoperation mainly by supporting: Repeatedly attainable fast startups with the greatest possible regardto the lifetime of heavy-walled components. Quickest possible restoration of power supply to the grid after anydisturbance Saves startup time by avoiding boiler trip on turbine trip. Ensures high reliability and availability of the plant Bypass systems contribute to the overall target of safe andefficient supply of electric power at minimum total cost. Steam bypass systems bring substantial fuel savings whilethey solve many of the problems caused by using baseloadgenerating units for cyclic operationTurbine Bypass SystemTurbine Bypass System
    74. 74.  The steam bypass system is generally used during thefollowing modes of operation: Start-up and shutdown, Steam turbine trip, Steam turbine no-load or low-load operation Fast Run back Fast load throw off House load operationTurbine Bypass SystemTurbine Bypass System
    75. 75. Turbine Bypass System for Thermal PlantTurbine Bypass System for Thermal Plant
    76. 76. Turbine Bypass System for CCP PlantTurbine Bypass System for CCP Plant
    77. 77. Typical Large Steam TurbineTypical Large Steam TurbineExtraction Steam and Heater SystemsExtraction Steam and Heater SystemsI PTurbineH PTurbineHighPressureHeatersHighPressureHeatersHighPressureHeatersBoilerFeedPumpsLowPressureHeaterLowPressureHeaterDeaeraterHeatedFeedwaterto BoilerBFP Recirc.CondensateTo HotwellLP Turbine
    78. 78. Automatic Turbine Start-up Control &Automatic Turbine Start-up Control &Rotor Stress MonitoringRotor Stress Monitoring Safe Turbine Start-up and Shut down Sequencing OEM guidelines are incorporated using the flowcharts androtor stress constants ATC mode automatically determines: Speed & Load Targets Speed Rates & Speed Holds Load Rates & Load Holds Run backs Integral Turbine Protections
    79. 79. Typical ATC and RSM ProgramsTypical ATC and RSM Programs HP and IP rotor stress calculations Steam chest metal required temperature calculations Turning gear checks before startup Eccentricity and vibration monitoring Water detection and drain valve control Bearing temperature monitoring Generator monitoring and checks before synchronization Heat soak calculations allowing for shorter heat soak time
    80. 80. DamperControlSteamTempFeedwaterHRSG TurbineTurbineMasterS-heatSprayR-heatSprayBF-PumpTurbineValvesLoad DemandComputerHigh LimitLow LimitRamp RateOperatorSet LimitsRunbacksRundownsBlock IncreaseBlock DecreaseLocalRemoteGT #1 GT #2ST MWST MWDELTADELTABALANCERBALANCER+-Load Demand Computer – CCP PlantsLoad Demand Computer – CCP Plants
    81. 81.  Front end (LDC Indexer) develops total plant MW demand GT MW demand is total plant demand minus actual ST MWgeneration GTs are in megawatt control mode ST is in IPC control mode As plant load index increases, the ST TP set point increases f(x) has minimum pressure (floor value) f(x) curve slides pressure on 100% valve pointBasic CC PlantBasic CC PlantControlControl
    82. 82. Emerson Gas TurbineEmerson Gas TurbineControlControl Automatic startup and shutdown Surge control limited starting and under load Feed-forward fuel control schedule duringstarting Temperature override control during starting Speed control from tuning gear to minimumload Load control from minimum to base load Loading rate control Temperature control at load Minimum and maximum limits on fuel flow
    83. 83. Ovation Gas Turbine Controls OfferOvation Gas Turbine Controls OfferNumerous AdvantagesNumerous Advantages Advanced control and turbine protectionschemes Local and remote operation capability Improved data acquisition for predictivemaintenance and scheduling Integrated power and BOP controlsystems Maximize efficiency through loadmanagement More precise and reliable fuel control Advanced graphical interface Historical logging and trending Diagnostics for preventative maintenance
    84. 84. Modern Power Plant ConsiderationsModern Power Plant Considerations Power industry is experiencing a dramatic changes fueled by Deregulation andconsolidation. Older business models are changing to cope with Competition between utilities,environmental concerns, and increasing power demand. Availability, reliability, efficiency & lesser operating costs have become keyelements of everyday plant operation considerations. Today’s control system networks have become Information networks Modern power plants tending to achieve vertical and horizontal integration ofplant wide controls under single hardware/software platform, using Smart FiledDevices and Industrial standard communication across various layers ofinformation & control networks. Integrated Plant Optimization suites enable efficient optimized continuous plantcontrols throughout the plant operation range. Plant Web Digital architecture enables easy integration of field devises whileensuring high quality field intelligence made available to the right persons,minimizing operational & maintenance costs while maximizing safety. Integrated Plant Simulator for efficient operation and management of the plant
    85. 85. Air ControlsFuelManagementFeedwaterControlBurnerManagementCondensateControlEmergencyDieselCirculatingWaterTurbineBypassCombustionControlCoordinatedControlsAGCCoolingTowerSwitchyard/MeteringSCRInjectionReagentHandlingAmmoniaHandlingSootblower PLCI/OFly Ash PLCI/OBottom Ash PLCI/ODry ESP PLCI/OWet ESP PLCI/OCondensatePolishingPLCI/OAirPreheaterPLCI/OCoalHandlingPLCI/OLimestoneStockoutPLCI/OGypsumHandlingPLCI/OAuxBoilerPLCI/OMakeupWaterPLCI/ODeminWaterPLCI/OPLCI/OLimestoneReclaimPLC StationsHardwiredDataLinksTurbine StationEmissions StationVibrationMonitoring StationHardwiredDataLinksTurbineControlEmissionsMonitoringMotor/TransformerUPSMonitoringVibrationMonitoringFireDetectionDCS Operator StationsDCS EngineerStation HistorianTypical Power Plant Controls ArchitectureTypical Power Plant Controls ArchitecturePLCsPLCs DCSDCS33rdrdPartyPartySystemsSystemsLocalDisplayLocalDisplayLocalDisplayEmerson Confidential
    86. 86. Air ControlsAir Controls FuelManagementFuelManagementFeedwaterControlFeedwaterControlBurnerManagementBurnerManagementCondensateControlCondensateControlEmergencyDieselEmergencyDieselCirculatingWaterCirculatingWaterTurbineBypassTurbineBypassCombustionControlCombustionControlCoordinatedControlsCoordinatedControlsAGCAGC CoolingTowerCoolingTowerSwitchyard/MeteringSwitchyard/MeteringSCRInjectionSCRInjectionReagentHandlingReagentHandlingAmmoniaHandlingAmmoniaHandlingTurbineControlTurbineControlEmissionsMonitoringEmissionsMonitoringMotor/TransformerMotor/TransformerUPSMonitoringUPSMonitoringVibrationMonitoringVibrationMonitoringFireDetectionFireDetectionEngineerStationHistorianSootblowerSootblowerFly AshFly AshBottom AshBottom AshDry ESPDry ESPWet ESPWet ESPCondensatePolishingCondensatePolishingAirPreheaterAirPreheaterCoalHandlingCoalHandlingLimestoneStockoutLimestoneStockoutGypsumHandlingGypsumHandlingAuxBoilerAuxBoilerMakeupWaterMakeupWaterDeminWaterDeminWaterLimestoneReclaimLimestoneReclaimEmerson’s Modern Power Plant ControlsEmerson’s Modern Power Plant ControlsAssetMgmtStationWireless andWeb-basedInterfacesFieldbus-based Ovation Expert SystemSimulatorOperator StationsEmerson Confidential
    87. 87. Total Solutions From The Power IndustryTotal Solutions From The Power IndustrySpecialistsSpecialistsBusiness LevelOptimization & PredictiveMaintenanceExpert ControlInstrumentationApplications