Learning Powerplant Basics

7/28/2019 Learning Powerplant Basics

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Amit Prakash 1

POWER GENERATION

PROCESSBASICS


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BOILER / STEAM TURBO-GENERATOR

UTILITY PLANT

Boiler

100%

Fuel

Air

Stack

Steam

Steam Turbine Generator

20%

Lake

6% Aux. Power + Losses

Steam Condenser40%

34% Electricity

THERMAL EFFICIENCY - 34%

Transmission


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BOILER / STEAM TURBINE-GENERATOR

INDUSTRIAL CO-GENERATION

Boiler

Fuel

100%

Air

Stack

15%

Steam Turbine Generator

15% Electricity

Transmission

Steam 5% Aux. Power + Losses

Process Steam

65%

Process Plant

THERMAL EFFICIENCY - 80%


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Amit Prakash 5

Air

CompressorTransmissionGenerator

GAS TURBINE

INDUSTRIAL CO-GENERATION PLANT

Turbine

100% Fuel

Combuster Exhaust Gas

20%

StackStack

Process PlantProcess Steam

Supplementary/

Auxiliary

Fuel (Optional)


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Amit Prakash 6

Air

CompressorTransmissionGenerator

GAS TURBINE

COMBINED 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

Supplementary

Fuel (Optional)

Thermal Efficiency - 45-55%


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UTILITYPLANT - FUNCTIONALBLOCKDIAGRAM

Switch Yard SystemStation 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 & Control

System

Generator & Electrical System

Boiler Steam & Water System

Air & Flue Gas System

Fuel Preparation System

Fuel Firing System

Boiler Miscellaneous Systems

Ash Handling System


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CAPTIVE POWER PLANT - FUNCTIONALBLOCK

DIAGRAM

Switch Yard System Station Electrical System

DM Plant Fuel Handling System Station Miscellaneous Systems

BFPs & 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


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BOILER FUNDAMENTALS


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BASIC DIAGRAM OF A BOILER

Steam / Water System

Furnace

Heat Transfer

SurfaceMixing of

Fuel & Air

Water

Fuel

Air

Steam

Flue Gas

Ash

Blowdown


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SALIENT FEATURES OF MODERN INDUSTRIAL

& UTILITY BOILER

STEAM BOILER

WATER TUBE

SUPERHEATED STEAM

HIGH PRESSURE

WATER COOLED FURNACE

WATER CIRCULATION


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COMBUSTION REQUIREMENTS

3 Ts of Combustion

Combustion

Time

Temperature

Turbulence

Sufficient

Combustion Air

Fuel

is

Gasified

Mixing within

Flammable

Range

Temperature

above

Ignition

Point


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BASIC COMBUSTION CHEMISTRY

Complete

O2 +H2

C

Heat

(Air) Oxygen Fuel

Products

H2O

CO2

Incomplete

+

Heat

O2

H2

C

Oxygen Fuel

Flue Gas

Flue Gas

Products

H2O

CO2

COH2

C

Other Combustibles - Sulphur to Sulphur Oxides

Non-combustible - Nitrogen to Nitrogen+Nitrous Oxides

Ash


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BOILER WATER & STEAM SYSTEM

Furnace

Water Wall

Risers

Drum

DownComersEconomiser

Feed Water

Primary

Super

Heater

Final

Super

Heater

Primary

Re

Heater

Final

Re

Heater

Platen

Super

Heater

Attemperator

Spray

Water

Spray

Water

Main Steam

Hot Reheat

Steam

Cold

Reheat

Steam

Bottom Ring Header

Simplified Process Diagram

Flue Gas

Flue Gas

Out to

Air Heater

Attemperator


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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


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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


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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


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AIR & FLUE GAS SYSTEM


ChimneyID 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 Cold

PA Header

To Hot

PA Header

E

C

O

L

TS

H

FURNACER

H

P

TN

S

H

F

IN

S

H

WINDOX A

WINDBOX B

From

FD Fans

To Air Cooled

Guns

Scanner Air Fans


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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 pressureand speed

Flue Gas Cleaning

Gas flow is restricted by ash deposits on boiler surfaces


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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


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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


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FUEL PREPARATION SYSTEM - COAL


Hot PA

Cold PAMill A

Raw Coal Bunker

Coal Feeder

Coal+Air

to Burners

Seal Air FansTo Other Mills

To Mill Discharge

Valves

To

Other

Mills

To

Other

Mills


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FUEL PREPARATION SYSTEM - GAS/OIL


Fuel Gas

Supply To Burners

PRVs

FCV FGTV

FUEL GAS

FUEL OIL

Fuel OilSupply

PCV

Fuel Oil Pumps

To BurnersOil Heater

Steam

FCV FOTV

Fuel Oil

Return

Short

Recirc

Long

Recirc

Atomising

Steam/Air

PCV


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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 BoilerLoad


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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


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Process Regulation

Coal Flow - Raw Coal Feeder Speed

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


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FUEL FIRING SYSTEM

Typical Corner Arrangement

for 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


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FUEL FIRING SYSTEM


Fuel Firing - Front / Tangential

Fuel Oil Atomisation - Mechanical / Air / Steam

Flame Ignition

Air Distribution

Fuel Combustion


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FUEL FIRING SYSTEM

Major Equipment

Burners

Ignitors

Flame Scanners

Burner Tilt Mechanism

Wind Box

Dampers


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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


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BOILER MISCELLANEOUS SYSTEMS

Boiler Auxiliary Cooling Water System

Ensures continuous supply of cooling water to Boiler & its 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


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Deaerator

Feed Storage Tank

M

Discharge Valve

Recirculation

Valve

Boiler Feed Pumps

To HP

Heaters

To HP Bypass

Spray

T o APRDS

Spray

Hydrazine

Dosing

Ammonia

Dosing

Aux. Steam

for

Pegging

HP Heater Drains

Condensate from LP Heater

Aux. Steam

CRH Steam

IPT Extraction

Steam


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Boiler Water pre-heating & air removal

Maintain positive Suction Pressure for Feed Pumps

Feed Water Pumping to Boiler


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Major Equipment

Boiler Feed Pumps

Hydraulic Coupling

Deaerator


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Process Regulation

Deaerator Pressure

Deaerator Level

BFP Minimum Recirculation

Feed Pump Speed


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STEAM TURBINE FUNDAMENTALS


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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


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BASIC RANKINE CYCLE

T

S

Unavailable Heat

Heat Available

for Work


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IMPROVING RANKINE CYCLE

Superheating

Increased Pressure

Decreased Exhaust Pressure

Regenerative Feed Heating

Reheating


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STEAM TURBINE TYPES

Condensing Turbine

Back Pressure Turbine

Regenerative Turbine

Controlled Extraction

No. of Cylinders

Speed - Constant / Variable

Single / Double Flow

S A S S


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TURBINE STEAM SYSTEM


Condenser

HPTurbine

IPTurbine LP

Turbine

Extraction

Steam

Main

Steam

Cold

Reheat

Steam

Hot

Reheat

Steam

ESV CV

IV CV



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Major Equipment

Turbine - Casing, Rotor & Blades

Emergency Stop Valves

Control Valves

Condenser



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Process Regulation

Steam Admission

Emergency Shutdown

REGENERATIVE FEED HEATING SYSTEM


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From BFP

Discharge

To

Boiler

HP

HTR

HP

HTR

CRH

Steam

ToDeaerator

IPT

Extrn.

Steam

Condenser

Hotwell

Condensate Extraction

Pump

LP

HTR

LP

HTR

HP

Flash

Tank

LP

Flash

Tank

To

Deaerator LPT

Extraction Steam

LPT

Extraction Steam

Minimum

Recirculation

LP

HTR

Drain

CLRGSC

To

Condenser

To

Condenser

Gland

Leakoff

Steam

LPT Extraction

Makeup


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Pumping of Condensate from Hotwell to Deaerator

Gradual Heating of Feed Water Temperature

Minimise Heat Loss from the Cycle


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Major Equipment

HP Heaters

LP Heaters

Drain Cooler

Condensate Extraction Pumps


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Process Regulation

Hotwell Level

Heater Level

Minimum Flow through CEP & GSC


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TURBINE GOVERNING & CONTROL SYSTEM

Functional Block Diagram

Gland

SteamSystem

Lubricating

Oil

System

Governing

Oil

System

Turning

Gear

Jacking

Oil

System

Condenser

Vacuum

System

Turbine

DrainSystem

OIL SYSTEMSVACUUM SYSTEM WARM UP SYSTEM


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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



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Amit Prakash 50


Major Equipment

Oil Pumps, Turning Gear & Jacking Oil Pump

Hydraulic Actuators for Turbine Valves

Vacuum Pumps

Gland Steam Pressure Regulator

Oil Coolers & Temperature Regulator



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Process Regulation

Speed / Load / Frequency Control

Gland Steam Pressure Control

TURBINE MISCELLANEOUS SYSTEMS


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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 & its 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



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Cooling

Tower

CW

Sump

CW

Makeup

Water

Condenser

A

Waterbox

B

Circulating

Water Pumps

ToUnit#2

CW Return Header

CW Supply Header



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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


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Main

Steam

CRH

To HPT

From HPT

To IPTHRH

Feed

Water PRV

Spray

Control

Valve

Block

Valve

Condenser

Condensate



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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


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Process Regulation

MS Pressure Reduction & Desuperheating

HRH Steam Pressure Reduction & Desuperheating


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GENERATOR FUNDAMENTALS

WORKING PRINCIPLE


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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 - FrequencyN - No. of Turns in a Stator Winding Coil

F = Pn/120

P - No. of Poles

n - Revolution per second of Rotor

GENERATOR EFFICIENCY & LOSSES


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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


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Generator Functional Block Diagram

Unit

AuxiliaryTransformer

Field

ExcitationSystem

Generator

Synchronising

Sceme

Generator

Transformer

Metering &

Protective

Relays

Stator

Cooling WaterSystem

Hydrogen

Cooling

System

Seal

Oil

System

ELECTRICAL SYSTEMS MECHANICAL SYSTEMS



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Key One Line Diagram

132 KV Bus I

132 KV Bus II

Isolator

Circuit Breaker

GT

Generator

Unit

Auxiliary

Transformer

From

Station

Bus

From

Station

Bus

6.6 kV Unit Bus B6.6 kV Unit Bus A

11 kV



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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



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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



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Process Regulation

Field Excitation

Generator Synchrinisation

Voltage Regulation


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POWER PLANT

OPERATION & MAINTENANCE



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Efficiency Calculations

Boiler Efficiency - Direct / Heat Loss Method

Turbine Heat Rate - Total Heat Supplied/ KWHR

Plant Heat Rate - Heat Supplied/ KWHR



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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



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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)


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POWER PLANT

AUTOMATION &CONTROL

POWER PLANT AUTOMATION & CONTROL


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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



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Soot Blower Sequential Control

Wall Blowers

Long Retractable Blowers

Air Heater Blowers



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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



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Amit Prakash 74

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



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Amit Prakash 75

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



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Electro-hydraulic Governing System

Speed Control

Load Control

Load Shedding

Initial Pressure Control

AUTOMATION & CONTROL


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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


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Amit Prakash 78

OPEN LOOP CONTROL

Interlocking - Safe Startup / Shutdown

Protection - Emergency Shutdown (Trip)

Sequencial Control - Efficient Startup / Shutdown

CRITICAL OPEN LOOPS

ID/FD /PA Fans

BFP


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POWER PLANT

INSTRUMENTATION

POWER PLANT INSTRUMENTATION


80/80

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)

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