Power plant-basics

POWER GENERATIONPROCESS BASICS

BOILER / STEAM TURBO-GENERATORUTILITY PLANT

Boiler

100% Fuel

Air

Stack

Steam

Steam Turbine Generator

20%

Lake

6% Aux. Power + Losses

Steam Condenser40%

34% Electricity

THERMAL EFFICIENCY - 34%

Transmission

BOILER / STEAM TURBINE-GENERATORINDUSTRIAL CO-GENERATION

Boiler

Fuel100%

Air

Stack

15%

Steam Turbine Generator

15% Electricity

Transmission

Steam 5% Aux. Power + Losses

Process Steam65%

Process Plant

THERMAL EFFICIENCY - 80%

SIMPLE CYCLE COMBUSTION (GAS) TURBINE

Air

100% Fuel

Compressor Turbine Generator

Combuster

Stack

57-62%

3% Aux Power + Losses

35-40% Electricity

Transmission

THERMAL EFFICIENCY - 35-40%

Air

Compressor TransmissionGenerator

GAS TURBINEINDUSTRIAL CO-GENERATION PLANT

Turbine

100% Fuel

Combuster Exhaust Gas

20%

StackStack

Process PlantProcess Steam

Supplementary/AuxiliaryFuel (Optional)

Air

Compressor TransmissionGenerator

GAS TURBINECOMBINED CYCLE POWER PLANT

20%

Stack

100% Fuel

Combuster Exhaust Gas

Stack

Turbine

Steam Turbine

Steam

GeneratorTransmission

Steam Condenser

Lake

28%

6% Aux. Power + Losses

12-15% Electricity

35-40% Electricity

SupplementaryFuel (Optional)

Thermal Efficiency - 45-55%

UTILITY PLANT - FUNCTIONAL BLOCK DIAGRAMSwitch Yard System Station Electrical System

Boiler Feed Pumps & Deaerator System

Turbine Bypass System

BOILER

TURBINE-GENERATOR

UNIT#2

DM Plant Fuel Handling System Station Miscellaneous Systems

Turbine Miscellaneous Systems

Turbine Steam System

HP & LP Heaters System

Turbine Supervisory & ControlSystem

Generator & Electrical System

Boiler Steam & Water System

Air & Flue Gas System

Fuel Preparation System

Fuel Firing System

Boiler Miscellaneous Systems

Ash Handling System

CAPTIVE POWER PLANT - FUNCTIONAL BLOCK DIAGRAM

Switch Yard System Station Electrical System

DM Plant Fuel Handling System Station Miscellaneous Systems

BFP’s & Deaerator System

UNIT#2 UNIT#3

BOILER

TG

Steam & Water

Air & Flue Gas

Fuel Preparation

Fuel Firing

Steam

HP & LP Heaters

Supervisory & Control

Generator & Electrical

Miscellaneous Systems

Ash Handling System

BOILER FUNDAMENTALS

BASIC DIAGRAM OF A BOILER

Steam / Water System

Furnace

Heat TransferSurface

Mixing ofFuel & Air

Water

Fuel

Air

Steam

Flue Gas

Ash

Blowdown

SALIENT FEATURES OF MODERN INDUSTRIAL& UTILITY BOILER

• STEAM BOILER

• WATER TUBE

• SUPERHEATED STEAM

• HIGH PRESSURE

• WATER COOLED FURNACE

• WATER CIRCULATION

COMBUSTION REQUIREMENTS

3 T’s of Combustion

CombustionTimeTemperatureTurbulence

SufficientCombustion Air

Fuel isGasified

Mixing withinFlammableRange

TemperatureaboveIgnition Point

BASIC COMBUSTION CHEMISTRY

Complete

O2 +H2C

Heat

(Air) Oxygen Fuel

ProductsH2OCO2

Incomplete

+

Heat

O2

H2C

Oxygen Fuel

Flue Gas

Flue Gas

ProductsH2OCO2COH2C

• Other Combustibles - Sulphur to Sulphur Oxides• Non-combustible - Nitrogen to Nitrogen+Nitrous Oxides• Ash

BOILER WATER & STEAM SYSTEM

Furnace

Water WallRisers

Drum

DownComers

EconomiserFeed Water

PrimarySuperHeater

FinalSuperHeater

PrimaryReHeater

Final ReHeater

PlatenSuperHeater

Attemperator

SprayWater

SprayWater

Main Steam

Hot ReheatSteam

ColdReheat Steam

Bottom Ring Header

Simplified Process Diagram

Flue Gas

Flue GasOut toAir Heater

Attemperator


Process Performance Highlights

• Heat Transfer by Radiation and Convection

• Boiler Water Circulation - Natural or Controlled

• Heat Transfer depends on Heat Transfer Area & Time

• Heat Transfer is affected by Fouling, Boiler Pressure, Boiler Water Quality and % MCR Load


Major Equipment

• Economiser - Pre-heats Boiler Feed water

• Boiler Drum - Separates water from steam and reduce solids in steam

• Water Walls - Absorb heat from flue gas to evaporate boiler water

• Superheaters - Heat up steam coming from boiler drum

• Reheaters - Heat up steam coming from High Pressure turbine

• Attemperators - Reduce superheat from steam


Process Regulation

• Drum Level - Regulation of Feed Water flow

• Drum Water Quality - Blow down / Chemical Dozing

• Fouling of Heat Transfer Surfaces - Blowdown / Soot Blowing

• Main Steam Temperature - Attemperation / Burner Tilt

• Hot Reheat Steam Temperature - Burner Tilt / Attemperation

• Main Steam Pressure - Regulation of Combustion

AIR & FLUE GAS SYSTEM


Chimney

ID Fan A

ID Fan B

ESP A

ESP B

AH A

AH B

FD FAN A

FD FAN B

PA FAN A

PA FAN B

To ColdPA Header

To HotPA Header

ECO

LTSH

FURNACERH

PTNSH

FINSH

WINDOX A

WINDBOX B

FromFD Fans

To Air CooledGuns

Scanner Air Fans



• Generation of Draft - Natural / Induced / Forced / Balanced

• Supply of Air for Transport of Pulverised Coal

• Pre-heating of Air

• Distribution of Air in Combustion Chamber

• Recirculation of Gas

• Fan capacity depends on Flow, Density & System Resistance

• Fan performance is affected by temperature, density, barometric pressure and speed

• Flue Gas Cleaning

• Gas flow is restricted by ash deposits on boiler surfaces


Major Equipment

• Air Path - Forced Draft Fans, Steam Coil Air Pre-heater, Regenerative Air Pre-heater & Wind-box

• Gas Path - Induced Draft Fans and Stack

• Gas Recirculation - Gas Recirculating Fans

• Flue Gas Cleaning - Mechanical Precipitator, Electrostatic Precipitator and Gas Scrubber

• Dampers


Process Regulation

• Furnace Draft - ID Fan Inlet Vane Control and/or Variable Speed

• Secondary Air Flow - FD Fan Variable Pitch Control

• PA Header Pressure - PA Fan Inlet Vane Control

• RAPH Cold End Temperature - SCAPH Control

• Gas Recirculation - Damper Control

FUEL PREPARATION SYSTEM - COAL


Hot PA

Cold PAMill A

Raw Coal Bunker

Coal Feeder

Coal+Airto Burners

Seal Air FansTo Other Mills

To Mill DischargeValves

ToOtherMills

To OtherMills

FUEL PREPARATION SYSTEM - GAS/OIL


Fuel GasSupply To Burners

PRV’s

FCV FGTV

FUEL GAS

FUEL OIL

Fuel OilSupply

PCV

Fuel Oil Pumps

To BurnersOil Heater

Steam

FCV FOTV

Fuel OilReturn

ShortRecirc

LongRecirc

AtomisingSteam/Air

PCV

FUEL PREPARATION SYSTEM


• Coal Pulverizing - Direct / Indirect Firing

• Coal Transport and Drying

• Fuel Gas Pressure Regulation

• Fuel Oil Pumping & Filtering

• Fuel Oil Pressure & Viscosity Regulation

• Gas Pressure & Oil Pressure/Temperature affect Boiler Load


Major Equipment

• Coal Mills - Tube Ball / Bowl / Impact

• Raw Coal Feeders - Chain / Belt / Rotary / Gravimetric

• Coal / Air Dampers, Gates & Discharge Valves

• Fuel Oil Pumps & Heaters

• Seal Air Fans

• Coal Bunkers

• Vapour Fans


Process Regulation

• Coal Flow - Raw Coal Feeder Speed

• Coal/Air Temperature & Flow - Cold & Hot PA Flows

FUEL FIRING SYSTEM

Typical Corner Arrangementfor a Tangentially Fired System

Front Wall

Plan(Corner Designation)

(1)

(2) (3)

(4)

AA

A

AB

B

BC

C

CD

D

DE

E

EF

F

FF

Air Damper

OFA

OFA Over Fire Air

OFA

EA

EA End Air

FA

FA Fuel Air

AA

AA Aux. Air

Coal Burner

Fire Ball Scanner

LFO?HFO Burner

HFO Burner

Oil Flame Scanner

HEA Igniter

FUEL FIRING SYSTEM


• Fuel Firing - Front / Tangential

• Fuel Oil Atomisation - Mechanical / Air / Steam

• Flame Ignition

• Air Distribution

• Fuel Combustion

FUEL FIRING SYSTEM

Major Equipment

• Burners

• Ignitors

• Flame Scanners

• Burner Tilt Mechanism

• Wind Box

• Dampers

FUEL FIRING SYSTEM

Process Regulation

• Furnace to Wind Box Differential Pressure

• Fuel Air Flows

• Fuel Firing

• Emergency Shutdown

• Flame Monitoring

• Oil Support for Coal Flame Stability

BOILER MISCELLANEOUS SYSTEMS

Boiler Auxiliary Cooling Water System

• Ensures continuous supply of cooling water to Boiler & it’s auxiliaries

• Consists of Overhead Tank, Pumps & Heat Exchangers

Chemical Dosing System

• Prepares & supplies chemicals for treatment of Boiler Water

• Consists of Preparation Tanks, Mixers & Metering Pumps

DEAERATION & FEED PUMPING SYSTEM


Deaerator

Feed Storage Tank

M

Discharge Valve

RecirculationValve

Boiler Feed Pumps

To HPHeaters

To HP BypassSpray

T o APRDSSpray

HydrazineDosing

AmmoniaDosing

Aux. SteamforPegging

HP Heater Drains

Condensate from LP Heater

Aux. Steam

CRH Steam

IPT ExtractionSteam



• Boiler Water pre-heating & air removal

• Maintain positive Suction Pressure for Feed Pumps

• Feed Water Pumping to Boiler


Major Equipment

• Boiler Feed Pumps

• Hydraulic Coupling

• Deaerator


Process Regulation

• Deaerator Pressure

• Deaerator Level

• BFP Minimum Recirculation

• Feed Pump Speed

STEAM TURBINE FUNDAMENTALS

LAWS OF THERMODYNAMICS

• Conservation of Energy - Heat may be converted in to work and work may be converted in to heat, in accordance with a certain natural proportionality constant (ENERGY CAN NOT BE DESTROYED)

• Not all of a given quantity of Heat can be converted in to useful Work, because of irreversbility in the process (ENTROPY OF THE UNIVERSE IS INCREASING)

BASIC RANKINE CYCLE

T

S

Unavailable Heat

Heat Availablefor Work

IMPROVING RANKINE CYCLE

• Superheating

• Increased Pressure

• Decreased Exhaust Pressure

• Regenerative Feed Heating

• Reheating

STEAM TURBINE TYPES

• Condensing Turbine

• Back Pressure Turbine

• Regenerative Turbine

•Controlled Extraction

• No. of Cylinders

• Speed - Constant / Variable

• Single / Double Flow

TURBINE STEAM SYSTEM


Condenser

HPTurbine

IPTurbine LP Turbine

ExtractionSteam

MainSteam

ColdReheatSteam

HotReheatSteam

ESV CV

IV CV


Major Equipment

• Turbine - Casing, Rotor & Blades

• Emergency Stop Valves

• Control Valves

• Condenser


Process Regulation

• Steam Admission

• Emergency Shutdown

REGENERATIVE FEED HEATING SYSTEM


From BFPDischarge

ToBoiler

HPHTR

HPHTR

CRHSteam

To Deaerator

IPTExtrn.Steam

Condenser

Hotwell

Condensate ExtractionPump

LPHTR

LPHTR

HPFlashTank

LPFlashTank

ToDeaerator LPT

Extraction Steam

LPTExtraction Steam

MinimumRecirculation

LPHTR

DrainCLRGSC

ToCondenser

ToCondenser

GlandLeakoffSteam

LPT Extraction

Makeup



• Pumping of Condensate from Hotwell to Deaerator

•Gradual Heating of Feed Water Temperature

• Minimise Heat Loss from the Cycle


Major Equipment

• HP Heaters

• LP Heaters

• Drain Cooler

• Condensate Extraction Pumps


Process Regulation

• Hotwell Level

• Heater Level

• Minimum Flow through CEP & GSC

TURBINE GOVERNING & CONTROL SYSTEM

Functional Block Diagram

GlandSteamSystem

LubricatingOil

System

GoverningOilSystem

TurningGear

JackingOilSystem

CondenserVacuumSystem

TurbineDrainSystem

OIL SYSTEMS VACUUM SYSTEM WARM UP SYSTEM



• Shaft & Bearing Protection

• Electro-hydraulic Governing

• Maintain Vacuum in Condenser

• Supply Steam to Turbine Glands

• Warming up of Turbines and their Valves

• Emergency Shutdown in case of Unsafe Conditions


Major Equipment

• Oil Pumps, Turning Gear & Jacking Oil Pump

• Hydraulic Actuators for Turbine Valves

• Vacuum Pumps

• Gland Steam Pressure Regulator

• Oil Coolers & Temperature Regulator


Process Regulation

• Speed / Load / Frequency Control

• Gland Steam Pressure Control

TURBINE MISCELLANEOUS SYSTEMS

Condenser Cooling Water System

• Supplies Cooling Water Condensation of Turbine Exhaust Steam

Turbine Auxiliary Cooling Water System

• Ensures continuous supply of cooling water to Turbine & it’s auxiliaries

• Consists of Overhead Tank, Pumps & Heat Exchangers

Chemical Dosing System

• Prepares & supplies chemicals for treatment of Condensate

• Consists of Preparation Tanks, Mixers & Metering Pumps

TURBINE MISCELLANEOUS SYSTEMSCondenser Cooling Water System


CoolingTower

CWSump

CWMakeupWater

Condenser A

Waterbox B

CirculatingWater Pumps

ToUnit#2

CW Return Header

CW Supply Header

TURBINE MISCELLANEOUS SYSTEMSCondenser Cooling Water System

Major Equipment

• Cooling Towers• CW Pumps


• Steam Condensation• Cooling of Condenser CW - Cooling Tower / Lake

Process Regulation

• Condenser Tube Cleaning - Online / Back flushing

TURBINE BYPASS SYSTEM


MainSteam

CRH

To HPT

From HPT

To IPTHRH

FeedWater PRV

SprayControlValve

BlockValve

Condenser

Condensate



• Enable Boiler Operation for Quick Re-start after Boiler Trip and during Turbine Start-up

• Control MS Pressure after Turbine Trip or Sudden Load Throw-off


Process Regulation

• MS Pressure Reduction & Desuperheating

• HRH Steam Pressure Reduction & Desuperheating

GENERATOR FUNDAMENTALS

WORKING PRINCIPLE

• Converts Mechanical Energy in to Electrical Energy

• Based on Electro-magnetic Induction E = 4.44 O FN volts E - e. m. f. O - Strength of Magnetic Field F - Frequency N - No. of Turns in a Stator Winding Coil

F = Pn/120

P - No. of Poles n - Revolution per second of Rotor

GENERATOR EFFICIENCY & LOSSES

• Efficiency = Output Electrical Energy Input Mechanical Energy

• Losses - Bearing Loss, Copper Loss & Iron Loss

• Typically Efficiency is 90-97%

GENERATOR & UNIT ELECTRICAL SYSTEM

Generator Functional Block Diagram

UnitAuxiliaryTransformer

FieldExcitationSystem

GeneratorSynchronisingSceme

Generator Transformer

Metering &ProtectiveRelays

StatorCooling WaterSystem

HydrogenCoolingSystem

SealOilSystem

ELECTRICAL SYSTEMS MECHANICAL SYSTEMS


Key One Line Diagram

132 KV Bus I

132 KV Bus II

Isolator

Circuit Breaker

GT

Generator

UnitAuxiliaryTransformer

FromStationBus

FromStationBus

6.6 kV Unit Bus B6.6 kV Unit Bus A

11 kV



• Conversion of Mechanical Energy in to Electrical Energy

• Field Excitation

• Stator Winding Cooling by Distillate / Air

• Rotor Winding Cooling by Hydrogen / Air

• Hydrogen Sealing by Oil

• Synchronisation & Voltage Transformation

• Emergency Shutdown in case of Unsafe Conditions


Major Equipment

• Generator - Stator, Rotor, Armature Windings, Field Windings

• Field Excitation - Exciter (DC/AC), Static Rectifying Unit & AVR

• Bus Ducts & Transformers

• Circuit Breakers & Protective Relays

• H2 Cooling - Fans, Dryers & Coolers

• Stator Water Cooling - Pumps, Coolers & Overhead Tank

• Seal Oil - Pumps, Coolers & Differential Pressure Regulator


Process Regulation

• Field Excitation

• Generator Synchrinisation

• Voltage Regulation

POWER PLANTOPERATION & MAINTENANCE

OPERATION & MAINTENANCE

Efficiency Calculations

• Boiler Efficiency - Direct / Heat Loss Method

• Turbine Heat Rate - Total Heat Supplied/ KWHR

• Plant Heat Rate - Heat Supplied/ KWHR

Factors Affecting Plant Performance• Flue Gas Exit Temperature

• Excess Air

• Unburnt Fuel

• Steam Temperature

• Condenser Back Pressure

• FW Temperature at Eco Inlet

• Auxiliary Power Consumption

• Make up Water Flow

• Optimum Loading



• Start-up & Shutdown Monitoring

• Trip Analysis - Boiler / Turbine / Generator

• Equipment Run-Hour Monitoring

• History Trending

• Alarm Management

• Division of Operational Responsibilities

• Economic Load Allocation & Load Shedding (CPP)

POWER PLANTAUTOMATION &

CONTROL

POWER PLANT AUTOMATION & CONTROL

Burner Management System

• Furnace Purge Supervision

• Secondary Air Damper Modulation, On/Off Control and Supervision

• Light/Heavy Oil On/Off Control and Supervision

• Pulveriser and Feeder On/Off Control and Supervision

• Flame Scanning

• Overall Boiler Flame Failure Protection

• Boiler Trip Protection


Soot Blower Sequential Control

• Wall Blowers

• Long Retractable Blowers

• Air Heater Blowers


Automatic Turbine Run-up System

• Oil Supply Control - Turning Gear, Auxiliary Oil Pumps, Emergency Oil Pump, Jacking Oil Pump and Lube Oil Temperature

• Condensate & Evacuation Control - Condensate Extraction Pumps, Gland Steam Pressure, Vacuum Pumps and Vacuum Breaker Valve

• Turbine Control - Steam & Metal Temperature Matching, Warming up of HP ESV & CV, Steam Rolling & Acceleration and Auto Synchroniser


Turbine Stress Evaluator

• Calculation of Actual and Permissible Thermal Stress Values

• Comparison of Actual with Permissible Stress Values and Computation of Available Margin

• Optimize Start up, Operation and Shut down


Automatic Turbine Tester

• Safety Devices - Remote Trip, Over-speed, Low Vacuum and Thrust Bearing

• HP/IP Valves - HP Stop and Control Valves, and IP Stop and Control Valves


Electro-hydraulic Governing System

• Speed Control

• Load Control

• Load Shedding

• Initial Pressure Control

CRITICAL CLOSED LOOPS

• CMC - Boiler Follow / Turbine follow / Coordinated (Utility)

• Header Pressure Control (CPP)

• Combustion - Fuel / Air Flow

• Steam Temperature

• Drum Level

• Furnace Draft

AUTOMATION & CONTROL

AUTOMATION & CONTROL

OPEN LOOP CONTROL

• Interlocking - Safe Startup / Shutdown

• Protection - Emergency Shutdown (Trip)

• Sequencial Control - Efficient Startup / Shutdown

CRITICAL OPEN LOOPS

• ID/FD /PA Fans

• BFP

POWER PLANTINSTRUMENTATION

POWER PLANT INSTRUMENTATION

• Temperature - T/C & RTD

• Pressure

• Level - DP / Displacement / Hydra Step Drum Level Indicator

• Flow - DP / Annubar / Mag-flow

• Turbine Supervisory - Vibration/ Expansion/ Axial Shift/ Eccentricity

• Steam & Water Analysers - Conductivity/ pH/ DO2/ Silica

• Gas Analysers - O2/ CO2/ CO (in Flue Gas) Pollution Monitor H2 Purity (in Generator)

Power plant-basics

Design

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