POWER PLANT FAMILARISATION

(COAL BASED)

WHY TO OWN CAPTIVE POWER PLANT

Sl No

Description TG Set DG Set SEB

1Interruption of Power Supply

- NA - - NA - Possible

2Power Restriction / Demand Control

- NA - - NA - Possible

3Controlling of Voltage & Frequency

Possible Possible Not Possible

4 Initial Cost Very High High Less

5 Production CostRs. 2.75 /

UnitRs. 3.80 /

Unit

Demand : Rs. 150 / KVA

Energy : Rs. 7.15 / Unit

6 Pollution Problem Less Less Nil

7Banking / Selling of Excess Power

Possible Possible - NA -

8 Maintenance Cost Moderate Very High Less

FUEL

POWER PLANT

Non Conventional Fuel / Sources Conventional Fuel

WindSolar

OceanHusk

Baggas

DieselFurnace Oil

CoalLignite

Gas

Non-Conventional Fuel

Coal to Electricity ….. Basics

Coal

Chemical Energy

Super Heated Steam

Pollutants

Thermal Energy

Turbine Torque

Heat Loss In Condenser

Kinetic Energy

Electrical Energy

Alternating current in Stator

Mech. Energy Loss

ASHHeat

Loss

Elet. Energy Loss

POWER PLANT CYCLES

• SIMPLE RANKINE CYCLE.

• REHEAT CYCLE.

• REGENERATIVE CYCLE.

RANKINE CYCLE• The Carnot Cycle is theoretically most efficient, but it is

having practical difficulties.• For steam power plant, practical thermal cycle was

suggested by Rankine, called Ideal cycle or Rankine cycle.

3-3’ – BFP raises pressure from p2 to p1

3’-4 – Heating In feed heaters & eco

4 -1 – Heating In boiler

1-2 – Work done in Turbine from p1 to p2

1

23

3’

4

T

S

T1

T2

p1

p2

THERMAL EFFICIENCY OF RANKINE CYCLE Q1-Q2 W Useful work• η = ------- = --- = ----------------

Q1 Q Heat supplied

Rejected Heat • η = 1 - -------------------- Useful Heat

T1 - T2 T2• η Carnot = -------- = 1 - ---

T1 T1

• To achieve more efficiency T2 should be as low as

possible and T1 should be as high as possible

METHODS OF INCREASING RANKINE CYCLE EFFICIENCY

Raising supply temperature by super heating.

Increasing the inlet temperature will raise the heat supply to the

cycle more than the heat rejection.

Raising inlet pressure of steam : Increasing the pressure will mean increase in saturation

temperature at which steam evaporates thus increasing the average inlet temperature (T1)

Dropping the final pressure (or temperature) at which heat is

rejected.

Regenerative Heating : Heating the feed water pumped to Boiler

by bleeding steam from turbine.

Reheat Cycle : Reheating of steam in boiler after it has already

expanded in HP Turbine will avoid moisture formation in LT

Turbine. Also, more heat content of steam before IP Turbine,

will improve efficiency.

WHY SUPERCRITICAL PRESSURE

A Boiler operating at a pressure above critical point is called ‘SUPERCRITICAL BOILER’

A point where boiling water and dry saturated lines meet so that associated latent heat is zero, this point is called Critical Point and occurs at 225 kg/cm2 (abs) 374.15º C temperature.

CRITICAL CONDITION

Definition

“CRITICAL” is a thermodynamic expression describing the state of a substance beyond which there is no clear distinction between the liquid and gaseous phase.

• The critical pressure & temperature for water are • Pressure = 225.56 Kg / cm2• Temperature = 374.15° C

254 Kg/cm2

0

100

200

300

400

500

600

SUPER CRITICAL BOILER CYCLE WITH SH, RH & Regeneration

571°C 569°C

Steam flow :2111 T/HrSteam temp : 571 °CSteam Pres : 254 kg/cm2

RH pre : 47.3 Kg/cm2

RH Temp : 569°CFeed water Temp : 282°C

ENTROPY

TEMP

SUPERCRITICAL BOILER

• Supercritical pressure boiler has no drum and heat absorbing surface being, in effect, one continuous

tube, hence called ‘once through Supercritical pressure boilers.’

• The water in boiler is pressurized by Boiler Feed Pump, sensible heat is added in feed heaters, economizer and furnace tubes, until water attains saturation temperature and flashes instantaneously to dry saturated steam and super heating commences.

SUPERCRITICALTHERMAL CYCLE ADVANTAGES

• Improvements in plant efficiency by more than 2 %

• Decrease in Coal Consumption

• Reduction in Green House gases.

• Overall reduction in Auxiliary Power consumption.

• Reduction in requirement of Ash dyke Land & Consumptive water.

INCREASE IN PLANT EFFICIENCY by

SUPER CRITICAL PARAMETERS1.5

0.90.6

3.2

167 bar538/538’c

250 bar538/538

250 bar540/560’c

250 bar580/600’c

250bar566/566 ‘c

1

2

3

4

5

6

.

Efficiency Increase

COMPARISION OF THERMAL CYCLE EFFICIENCIES.

• OPEN CYCLE EFFICIENCY - 14.68 %

• WITH CONDENSER - 26.2 %

• WITH SUPER HEAT – 30.75 TO 34.15 %

• WITH REHEAT - 34.2 TO 36.6 %

• WITH SUPER CRITICAL PARAMETERS-

36.0 TO

39.15 %

• Efficiency of the cycle= Net W.D/Heat input

η = 1 - T2 T1 Where ,

T1 = Temp. of heat source

T2 = Temp. of heat sink

Steam Power Plant

Steam Theory

• Within the steam generator, fuel and air are force into the furnace by the burner.

• There, it burns to produce heat

• From there, the flue gases travel throughout the boiler.

• The water absorbs the heat, and eventually absorb enough to change into a gaseous state - steam.

• Boiler makers have developed various designs to squeeze the most energy out of fuel and to maximized its transfer to the water.

• To the right is the basic theoretical design of a modern boiler.

Furnace absorption

Platen SH

Divisional SHReheater

FSH

Economizer APH

Combustion Losses C & R losses

Hot Exhaust Gaslosses

MAJOR SECTIONS OF THERMAL POWER PLANT

• Coal Handling

• Boiler & its Auxiliaries

• Turbine & its Auxiliaries

• Cooling Tower & Condenser

• Water Treatment Plant & Water Handling

• Ash Handling System

CHS comprises of following systems:

Unloading System, Stacking, Screening & Crushing, Reclaiming, Bunker Feeding system.

GENERAL SYSTEM DESCRIPTION:

1.Unloading System

Coal Shall received at site through wagons and shall be unloaded by a. Wagon Tippler. b. Track Hoppers.

2. Stacking:

When boiler bunkers are full, coal shall be diverted to stockpile through reversible belt feeder.

The long travel Reversible Stacker cum Reclaimer shall be mounted on yard conveyers for stacking & reclaiming.

Normally, 2 nos of stock piles will be formed on each side of SCR. Total 4 nos stockpiles of trapezoidal cross section of height 10m, length 650m & width at base 49m. The storage capacity is for 15 days at 90 % PLF. Coal stored shall be (-) 100mm.

3. Screening & Crushing:Vibrating grizzly screens to separate (-) 25 mm coal before feeding the coal into crusher. (-) 100 mm coal size shall be fed to Ring Granular Type Crusher for crushing coal to (-) 25mm size. Crushed coal will be fed further into Boiler coal bunkers through belt conveyers.

4. Reclaiming:The coal from stock pile shall be reclaimed by bucket wheel reclaimer to feed onto reversible yard conveyer for conveying into crusher house.

5. Bunker Feeding system: Crushed coal from crushers shall be discharged onto belt

conveyers for feeding into junction towers. Coal from JT shall be fed into boiler coal bunkers with the help of travelling trippers.

Raw Coal

Belt Conveyor

Primary Screen

Crusher Less than 25MM

Secondary Screen

Belt Conveyor

Coal Bunker

More than 25mm Less than 25mm

BOILER

• WHAT IS BOILER

• TYPES OF BOILER

• CIRCULATION

WHAT IS BOILER

• A BOILER OR STEAM GENERATOR IS A CLOSED VESSEL IN WHICH STEAM IS GENERATED BY HEATING THE WATER BY COMBUSTION OF FUEL IN FURNACE.

• ANY CLOSED VESSEL EXCEEDING 22.75 LITRES IN CAPACITY WHICH IS USED EXPRESSLY FOR GENERATING STEAM UNDER PRESSURE AND INCLUDES ANY MOUNTING OR OTHER FITING ATTACHED TO SUCH A VESSEL WHICH IS WHOLLY OR PARTLY UNDER PRESSURE WHEN STEAM IS SHUT.

TYPES OF BOILER

1. MODE OF CIRCULATION OF WORKING FLUID2. TYPE OF FUEL3. MODE OF FIRING4. NATURE OF HEAT SOURCE5. WORKING PRESSURE6. SPECIFIC PURPOSE OF UTILISATION7. MANUFACTURERS TRADE NAME

CIRCULATION

• MOTION OF WORKING FLUIDS IN EVAPORATOR

TYPES CIRCULATION

1. NATURAL CIRCULATIONCIRCULATION BY MEANS OF DENSITY DIFFERENCE

2. FORCED CIRCULATIONCIRCULATION BY MEANS EXTERNAL FORCE LIKE PUMPING

Boiler Mixed Nozzle

Economizer

Chimney

ID fan

ESPAir Heater

FD Fan

PA Fan

Coal Bunker

Chain Feeder

Boiler Section – Flow DiagramSteam to Turbine

From HP Heater

Inle

t to

Boil

er

No. 1

HP Heater

BFBP

MD-BFP

CEP

GSC

No.7AB&8AB

LP Heater

No.5 LP Heater

DEAERATOR

CONDENSER

LPT LPT IPT HPT

No. 2

HP Heater

No. 3

HP Heater

BRCP

LTRH I/L Header

LTRH

ECO I/L Header

LTSH

ECO

No.6 LP Heater

HP BFWP

CRP

SEPARATOR

SEPARATOR

DRAIN TANK

ROOF TUBE

I/L Header

SH DIV Panel

FSHFRH

VERTICAL WATER WALL

SPIRAL WATER WALL

MSP

HRP

HP-BP

LP-BP

WW LOWER Header

GG

TD-BFP

A B

BA

A B C

Steam Turbine

• A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work.

Steam Flows from Boiler to turbine

Bypass Turbine

HPT

IPT LPT A LPT B

CPU

GSC

Condensor (HP) Condenser

(LP)

2

HPH

- 1

HPH

- 2

HPH

-3

EXT From CRH

LPH -5LPH -6

LPH -7ALPH -7B

LPH -8ALPH -8B

3

Deaerator

BFBP

TDBFP

Boiler

CEP3x50%

2x50%

FCS

5 56 6

2x50%

From Reheater

Economiser

(MD BFP 1x35%)

(MD BFBP 1x35%)

78

78 8

778

1

Condenser

Extraction system of A Large Steam Turbine Reheat Steam

HP

Main Steam

Steam for Reheating

IP

LPLP

HPH HPH/TDBFP LPH

LPH

LPH

Condenser

Steam from last stage of LPT Exhausts on condenser tube

condensation of steam takes place

Water collected in hot well

Cooling Water System

HOT WATER

COLD WATER

Cold Water

Cooling Tower

CW Pump

Condenser

CCCW Pump

ACW Pump

Equipments

Heat Exchanger

Circulating water scheme

• A circulating water pump house • Intake channel• Trash rack• A chlorination plant• Traveling water screen• Connecting pipe line to condensed• Outlet channel• A cooling tower

Closed Loop system:

Condenser

River Flow

Steam from Turbine

Pump for make up

Hot mist

CW Pump

Cooling TowerHot water

Cold Water

CW scheme…

Reservoir/ River Canal Intake

Trash rack

TWS

CW pumps

Condenser

Hot Pond

CT pumps

Cooling tower

Condensate & Feed Water System

Low Pressure Heaters

D/A

Feed Storage Tank

High Pressure HeatersCEP-BCEP-A

BFPs

HOT WELL

Boiler

HOT WATER STEAMWARM WATER

A B C

Cascade Aerator

Gas Chlorination

Stilling Chamber

Raw Water

Flash Mixer Flocculator

Tube Settler

Clarified Water Storage Tank

To RO MB Plant

Poly-electrolyteFeCl3

Alum, Lime

Alum, Lime

Alum, Lime

PRE TREATMENT PLANT

Poly Dosing

Poly Dosing

Poly Dosing

Clarifier Soft Water Pumps

Clarified Water

Storage

Tank

Filter Feed

Pumps

CT Make Up Line

Multi Grade Filter

Ultra Filtratio

n

Micron Cartridge Filter

De- gassifier

RO Feed

Pumps

RO High Pressure Pumps

RO Membra

nes

RO Permit Tank

MB Feed

Pumps

Mixed Bed

DM Water Tanks

DM Water Distributi

on

Water Flow Diagram (WTP)

Water Flow Diagram(DM Water)

DM Water Tank

CondensateTank

De-Aerator Boiler Turbine

Water Cooled

Condenser

What is Ash

• Ash is Oxidized form of the mineral matters present in coal

• Typical ash composition:Sio2,Al2O

3,Fe

2O

3,CaO,MgO etc

• Coal with more Sio2 & Al

2O

3, Ash MP > 1400°C

• Coal with more Fe2O3, CaO & MgO Ash MP < 1100°C

General Description:Ash Handling System comprises of following sub

systems:

1. BOTTOM ASH HANDLING SYSTEM:A. Bottom Ash Hopper with accessoriesB. Bottom Ash Overflow Transfer SystemC. Bottom Ash area drain Transfer SystemD. Economizer Ash Disposal System

2. FLY ASH HANDLING SYSTEMA. Vacuum Conveying SystemB. Pressure Conveying System

3. SILO UNLOADING SYSTEM4. WATER SUPPLY SYSTEM5. ASH SLURRY DISPOSAL SYSTEM6. HANDLING FACILITIES (CRANES & HOISTS)7. ASH SLURRY SUMP ACCESSORIES8. ASH SLURRY TRANSPORT PIPING9. AIR CONDITIONING & VENTILATION SYSTEM

Bottom Ash Handling System

Ash Slurry Sump

Ash

Pon

d

Ash Slurry Pumps – 4 sets ASPH

Eco Hopper-6nos

Flushing Appratus-6nos

Overflow Tank

Overflow Pump Settling Tank

Sludge Pumps

Ash Water Sump

AW

PH

FAHP-4Nos, BAHP-3Nos, LPW-4Nos

Water

Sludge

Bottom Ash Hopper

Feed Gate

Jet PumpClinker Grinder

Fly Ash Handling System

Surge Hopper

ESP hoppers-

RCC Silo

Conveying Compressor-

IA Compressor

Vacuum Pump

Unloading spout for Railway Wagon

Unloading spout for Closed Tanker

Ash Conditioner for Open Truck

for future Expansion

APH Hopper-

Flushing Apparatus

Air Washer-

Seal Box-

3 cell Collector

Master D Pump

Slave D Pump

Wetting s

Ash Slurry Pump House

Collector Tak-

Silo Fluidizing Blower

From Fly Ash HP Water Pump

COOLING TOWER

CW PUMP

GENERATOR

GENERATOR

TRANSFORMER

COAL MILL

BUNKER

FD FAN PA FAN

ID FAN

STACK

APH

BOILER

DRUM

CEP

BFP

LPH

HPH

ESPCONDENSER

Koradi Super Critical Expansion Power Project site (3 x660 MW) - Sunil Hi-Tech Engineers Limited

Typical Modern Power Plant Turbine

CONDENSATE & FEED WATER SYSTEM

HOT WELL

HOT WELL

CONDENSER

GSCDRAIN

COOLERLPH-1 LPH-2

LPH-3EJECTOR

D/A

D/A FST

HPH-5HPH-6FRS

TO BOILER

LP DOZING

CEP-B

CEP-A

BFP-A,B,C

HP Turbine Rotor

LP Turbine Rotor