Power Plant Basics

POWER GENERATION PROCESS BASICS

BOILER / STEAM TURBO-GENERATOR UTILITY PLANT 40%

Steam Condenser

20%

Stack Lake

Steam 6% Aux. Power + Losses

34% Electricity

100% Fuel Air

Boiler

Steam Turbine

Generator

THERMAL EFFICIENCY - 34%

Transmission

BOILER / STEAM TURBINE-GENERATOR INDUSTRIAL CO-GENERATION Process Steam 65% 15%

Process Plant Stack

Steam

5% Aux. Power + Losses 15% Electricity

Fuel 100% Air

Boiler

Steam Turbine

Generator

THERMAL EFFICIENCY - 80%

Transmission

SIMPLE CYCLE COMBUSTION (GAS) TURBINE

57-62%

100% Fuel

Stack Combuster

3% Aux Power + Losses 35-40% Electricity

Air

Compressor

Turbine

Generator

THERMAL EFFICIENCY - 35-40%

Transmission

GAS TURBINE INDUSTRIAL CO-GENERATION PLANT 20% Stack

Stack Supplementary/ Auxiliary Fuel (Optional)

Process Steam

Process Plant

100% Fuel Combuster

Exhaust Gas

Air

Compressor

Turbine

Generator

Transmission

GAS TURBINE COMBINED CYCLE POWER PLANT

28%

Steam Condenser 20% Stack

Stack

Steam

Supplementary Fuel (Optional)

Lake

100% Fuel Steam Turbine Combuster

Generator

Exhaust Gas

Air

6% Aux. Power + Losses

Compressor

Turbine

Generator

Thermal Efficiency - 45-55%

Transmission 12-15% Electricity

35-40% Electricity

Transmission

UTILITY PLANT - FUNCTIONAL BLOCK DIAGRAM Switch Yard System

Ash Handling System

Station Electrical System

Boiler Steam & Water System Air & Flue Gas System Fuel Preparation System

BOILER

Fuel Firing System Boiler Miscellaneous Systems Boiler Feed Pumps & Deaerator System

UNIT#2

Turbine Steam System TURBINEGENERATOR

HP & LP Heaters System Turbine Supervisory & Control System Generator & Electrical System Turbine Miscellaneous Systems Turbine Bypass System

DM Plant

Fuel Handling System

Station Miscellaneous Systems

CAPTIVE POWER PLANT - FUNCTIONAL BLOCK DIAGRAM Switch Yard System

Ash Handling System

Station Electrical System

Steam & Water BOILER

Air & Flue Gas Fuel Preparation Fuel Firing Steam

TG

UNIT#2

UNIT#3

HP & LP Heaters Supervisory & Control Generator & Electrical Miscellaneous Systems

BFP’s & Deaerator System DM Plant

Fuel Handling System

Station Miscellaneous Systems

BOILER FUNDAMENTALS

BASIC DIAGRAM OF A BOILER Steam

Water

Steam / Water System

Blowdown

Fuel

Flue Gas

Mixing of Fuel & Air

Air

Furnace

Heat Transfer Surface

Ash

SALIENT FEATURES OF MODERN INDUSTRIAL & UTILITY BOILER • STEAM BOILER • WATER TUBE • SUPERHEATED STEAM

• HIGH PRESSURE • WATER COOLED FURNACE • WATER CIRCULATION

COMBUSTION REQUIREMENTS

Sufficient Combustion Air

Fuel is Gasified

Mixing within Flammable Range

Temperature above Ignition Point

Combustion Time Temperature Turbulence 3 T’s of Combustion

BASIC COMBUSTION CHEMISTRY Complete (Air) Oxygen

O2

Fuel

+

Flue Gas Products H2O CO2

H2 C

Incomplete Oxygen

O2

Fuel

+

Heat

H2 C

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

Heat Flue Gas Products H2O CO2 CO H2 C

BOILER WATER & STEAM SYSTEM Drum

Spray Water

Hot Reheat Steam Main Steam

Attemperator Attemperator Platen Super Heater Down Comers

Final Re Heater

Primary Re Heater

Flue Gas

Final Super Heater

Primary Super Heater

Economiser

Furnace Flue Gas Out to Air Heater

Water Wall Risers

Bottom Ring Header

Simplified Process Diagram

Cold Reheat Steam

Spray Water

Feed Water

BOILER WATER & STEAM SYSTEM 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

BOILER WATER & STEAM SYSTEM 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

BOILER WATER & STEAM SYSTEM 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 To Air Cooled Guns

To Hot PA Header

From FD Fans

Scanner Air Fans

To Cold PA Header

PA FAN A

PA FAN B

WINDOX A AH A FURNACE

WINDBOX B

P T N S H

R H

F I N S H

L T S H

ESP A

E C O

ID Fan A Chimney ID Fan B AH B

ESP B

FD FAN A

FD FAN B

Simplified Process Diagram

AIR & FLUE GAS SYSTEM Process Performance Highlights • 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

AIR & FLUE GAS SYSTEM

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

AIR & FLUE GAS SYSTEM

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 To Mill Discharge Valves

Raw Coal Bunker

To Other Mills

Coal Feeder

Hot PA

Coal+Air to Burners

Mill A

To Other Mills

To Other Mills

Seal Air Fans

Simplified Process Diagram

Cold PA

FUEL PREPARATION SYSTEM - GAS/OIL Fuel Gas Supply

To Burners FCV

FGTV

PRV’s

FUEL GAS Atomising Steam/Air PCV Fuel Oil Return Short Recirc

PCV Fuel Oil Supply

Long Recirc

To Burners

Oil Heater FCV Fuel Oil Pumps

FOTV

Steam

FUEL OIL

Simplified Process Diagram

FUEL PREPARATION SYSTEM Process Performance Highlights • 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

FUEL PREPARATION SYSTEM 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

FUEL PREPARATION SYSTEM Process Regulation • Coal Flow - Raw Coal Feeder Speed • Coal/Air Temperature & Flow - Cold & Hot PA Flows

FUEL FIRING SYSTEM OFA OFA FF

EA

F

FA

EF

AA

(3)

(2)

E DE D CD C

Front Wall

Air Damper OFA

Over Fire Air

EA

End Air

FA

Fuel Air

AA

Aux. Air

(4)

(1) Plan (Corner Designation)

Coal Burner Fire Ball Scanner LFO?HFO Burner

BC HFO Burner

B

Oil Flame Scanner

AB A

HEA Igniter

AA

Typical Corner Arrangement for a Tangentially Fired System

FUEL FIRING SYSTEM Process Performance Highlights • 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 Condensate from LP Heater HP Heater Drains

Aux. Steam CRH Steam

Deaerator Aux. Steam for Pegging

To HP Heaters

IPT Extraction Steam Feed Storage Tank

To HP Bypass Spray

Hydrazine Dosing

T o APRDS Spray

Ammonia Dosing

Recirculation Valve M

Discharge Valve

Boiler Feed Pumps

Simplified Process Diagram

DEAERATION & FEED PUMPING SYSTEM

Process Performance Highlights • Boiler Water pre-heating & air removal • Maintain positive Suction Pressure for Feed Pumps • Feed Water Pumping to Boiler

DEAERATION & FEED PUMPING SYSTEM Major Equipment • Boiler Feed Pumps • Hydraulic Coupling • Deaerator

DEAERATION & FEED PUMPING SYSTEM

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 Heat Available for Work

Unavailable Heat

S

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 Main Steam ESV

CV

HP Turbine

IP Turbine

LP

Turbine

Cold Reheat Steam Condenser Hot Reheat Steam

IV

CV

Extraction Steam

Simplified Process Diagram

TURBINE STEAM SYSTEM Major Equipment • Turbine - Casing, Rotor & Blades • Emergency Stop Valves • Control Valves • Condenser

TURBINE STEAM SYSTEM

Process Regulation • Steam Admission • Emergency Shutdown

REGENERATIVE FEED HEATING SYSTEM To From BFP Boiler Discharge

CRH Steam To Deaerator

To Deaerator

LPT Extraction Steam

LP HTR

HP HTR

LPT Extraction Steam

IPT Extrn. Steam

LP HTR

HP HTR

To Condenser

Minimum Recirculation

Hotwell

Makeup

LPT Extraction

To Condenser HP Flash Tank

Condenser

Gland Leakoff Steam

GSC

LP HTR

Drain CLR

LP Flash Tank Condensate Extraction Pump

Simplified Process Diagram

REGENERATIVE FEED HEATING SYSTEM Process Performance Highlights • Pumping of Condensate from Hotwell to Deaerator •Gradual Heating of Feed Water Temperature • Minimise Heat Loss from the Cycle

REGENERATIVE FEED HEATING SYSTEM

Major Equipment • HP Heaters • LP Heaters • Drain Cooler • Condensate Extraction Pumps

REGENERATIVE FEED HEATING SYSTEM Process Regulation • Hotwell Level • Heater Level • Minimum Flow through CEP & GSC

TURBINE GOVERNING & CONTROL SYSTEM

Governing Oil System Turning Gear

Jacking Oil System

Condenser Vacuum System

Lubricating Oil System OIL SYSTEMS

Gland Steam System VACUUM SYSTEM

Turbine Drain System

WARM UP SYSTEM

Functional Block Diagram

TURBINE GOVERNING & CONTROL SYSTEM Process Performance Highlights • 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

TURBINE GOVERNING & CONTROL SYSTEM Major Equipment • Oil Pumps, Turning Gear & Jacking Oil Pump • Hydraulic Actuators for Turbine Valves • Vacuum Pumps • Gland Steam Pressure Regulator • Oil Coolers & Temperature Regulator

TURBINE GOVERNING & CONTROL SYSTEM 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 SYSTEMS Condenser Cooling Water System CW Return Header

Cooling Tower CW Sump

CW Makeup Water

To Unit#2

CW Supply Header

Circulating Water Pumps

Simplified Process Diagram

Condenser Waterbox A B

TURBINE MISCELLANEOUS SYSTEMS Condenser Cooling Water System Major Equipment • Cooling Towers • CW Pumps Process Performance Highlights • Steam Condensation • Cooling of Condenser CW - Cooling Tower / Lake Process Regulation • Condenser Tube Cleaning - Online / Back flushing

TURBINE BYPASS SYSTEM Main Steam

To HPT Feed Water

PRV Block Valve

Spray Control Valve

CRH

HRH

From HPT

To IPT

Condensate Condenser

Simplified Process Diagram

TURBINE BYPASS SYSTEM Process Performance Highlights • 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

TURBINE BYPASS SYSTEM 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

Metering & Protective Relays

Unit Auxiliary Transformer

Generator Transformer

Seal Oil System

Generator Synchronising Sceme

Hydrogen Cooling System

Field Excitation System

ELECTRICAL SYSTEMS

Stator Cooling Water System

MECHANICAL SYSTEMS

Generator Functional Block Diagram

GENERATOR & UNIT ELECTRICAL SYSTEM Isolator

132 KV Bus I

132 KV Bus II Circuit Breaker

Unit Auxiliary Transformer

GT

11 kV

From Station Bus Generator

6.6 kV Unit Bus A

Key One Line Diagram

From Station Bus 6.6 kV Unit Bus B

GENERATOR & UNIT ELECTRICAL SYSTEM Process Performance Highlights • 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

GENERATOR & UNIT ELECTRICAL SYSTEM 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

GENERATOR & UNIT ELECTRICAL SYSTEM Process Regulation • Field Excitation • Generator Synchrinisation • Voltage Regulation

POWER PLANT OPERATION & MAINTENANCE

OPERATION & MAINTENANCE Efficiency Calculations • Boiler Efficiency - Direct / Heat Loss Method • Turbine Heat Rate - Total Heat Supplied/ KWHR • Plant Heat Rate - Heat Supplied/ KWHR

OPERATION & MAINTENANCE 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

OPERATION & MAINTENANCE • 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 PLANT AUTOMATION & 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

POWER PLANT AUTOMATION & CONTROL

Soot Blower Sequential Control • Wall Blowers • Long Retractable Blowers • Air Heater Blowers

POWER PLANT AUTOMATION & CONTROL

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

POWER PLANT AUTOMATION & CONTROL 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

POWER PLANT AUTOMATION & CONTROL 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

POWER PLANT AUTOMATION & CONTROL Electro-hydraulic Governing System • Speed Control • Load Control • Load Shedding • Initial Pressure Control

AUTOMATION & 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 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 PLANT INSTRUMENTATION

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)