Enhancing Capacity – Empowering Nation Presentation on Supercritical Boilers 28 August 2012.

Enhancing Capacity – Empowering Nation

Presentation on Supercritical Boilers 28 August 2012

SupercriticalUltra Supercritical

&Advanced Ultra Supercritical

Steam Generators

New trends in Boiler Technology

SupercriticalUltra Supercritical

&Advanced Ultra Supercritical

Steam Generators

New trends in Boiler Technology

M. AnandarajDeputy General Manager

BHEL, Tiruchirappalli



Contents• BHEL Steam Generators• Emerging Market Requirements• Trends in Cycle parameters• Supercritical Boilers

• Major Systems• Startup System• Pressure part Arrangement• Firing System• High Temperature Materials

• Ultra Supercritical Boilers• Advanced Ultra Supercritical Boilers



BHEL Utility Units - A SummaryUnit Rating, MW

No. MW No. MW30 4 120 4 12060 16 960 16 960

67.5 9 607.5 8 54070 14 980 9 63080 14 1120 3 240

100 6 600 6 600110 39 4290 39 4290120 31 3720 27 3240125 7 875 1 125130 2 260 2 260150 17 2550 0 0200 24 4800 20 4000210 116 24360 114 23940250 58 14500 34 8500270 34 9180 0 0300 1 300 0 0500 82 41000 54 27000525 6 3150 2 1050600 22 13200 0 0660 12 7920 0 0700 1 700 0 0800 4 3200 0 0

TOTAL 519 138393 339 75495

Contracted Commissioned

62 % Total Installed

Capacity of India is

Contributed by BHEL Utility

Sets



Unit Contracted Commissioned

VU 40 46 45

VU 40 S 15 15

VU 60 38 19

MU 3 3

VP 23 16

V2R 17 17

HRSG 177 121

AFBC 72 59

CFBC 28 10

Others 28 28

Total 447 333

BHEL Industrial Units - A Summary



BHEL is currently adopting

Advanced Steam Cycles to Improve the Environmental & Economic Performance of

India’s Power Generation



Reference List of Supercritical Boilers

NTPC / BARH 2 x 660MW

APPDCL / Krishnapatnam 2 x 800 MW

PPGCL / BARA 3 x 660 MW

RPCL / Yermaras 2 x 800 MW

RPCL / Edlapur 1 x 800 MW

KPCL / Bellary 1 x 700 MW

LPGCL/Lalithpur- BHL 3 x 660 MW

DB Power / Singrauli 2 x 660 MW

NTPC / Mouda St. II 2 x 660 MW 18 Boilers Contracted



Emerging Market Requirements For Thermal Power Generation

High Reliability & Availability Highest Plant efficiency Suitable for differing modes of operation Suitable for varying fuel quality Minimum emission of Pollutants Lowest cost



Higher Plant efficiency for

• Conservation of fuel resources• Reduction of Atmospheric Pollutants - CO2 , SOX & NOX



Measures to improve Plant Efficiency

Cycle Parameters :• Higher steam parameters with Once Thro’ Boilers

Boiler side measures :• Highest Boiler Efficiency• Minimum RH spray• Minimum SH spray (if tapped off before feed heaters)• Reduced auxiliary power consumption



Increase of Plant Cycle Efficiency due toSteam Parameters

300241

175 538 / 538

538 / 566

566 / 566

580 / 600

600 / 620

6,77

5,79

3,74

5,74

4,81

2,76

4,26

3,44

1,47

3,37

2,64

0,75

2,42

1,78

00

1

2

3

4

5

6

7

8

9

10

HP / RH outlet temperature [deg. C]Pressure [bar]

Increase of efficiency [%]



500 MW Steam GeneratorCoal Consumption and Emissions

Subcritical Unit

Supercritical Unit

Coal Saving t/year Base 68800

CO2 Reduction t/year Base 88270

SO2 Reduction t/year Base 385

Basis:

Cycle Efficiency

%

Base

+1.0

No. of operating hrs.

Hrs./year 8000 8000



Current Trends in Steam Parameters

• 1980s : Pressure increased from 175-180 bar to 225 bar;

Temperature mostly around 540 °C

• 1990 : Pressures raised to 285 bar;

Temperature raised to 565-580-600 °C

• 300 bar & 620 °C not unusual today

• 255 bar & 568/596 °C commonly used presently



• Coal will continue to have maximum share towards installed capacity for electricity at least upto 2050

• CLEAN COAL TECHNOLOGY– Minimise CO2 emissions and environmental impact – Extend life of coal reserves

• Approach: Develop technology for SC, USC & Adv-USC power plants

14

# The improvements are with respect to the best units under construction in India

• Extension of coal reserves by 11%

• Competitive in electricity cost on deployment

Efficiency and CO2 Emission

Plant type with power rating

Steam Pressure (kg/cm2)

Steam Temperature

(C)

Efficiency (%)

CO2 Emissions (g/kW-hr)

Sub Critical (500 MWe)

170 540 35 900

# Super Critical 247 565 40 830

Ultra Super Critical 250 600 42 784

Advanced Ultra Super Critical

300 700 45 740



Trend in unit sizes & Cycle parameters

Unit SizeSHO Pressure

(kg/cm2(a))

SHO/RHO Temperature

(Deg.C)

Year of Introduction

60 / 70 MW 96 540 1965

110 / 120 MW 139 540/540 1966

200 / 210 MW 137 / 156 540/540 1972

250 MW 156 540/540 1991

500 MW 179179

540/540 540/568

19791985

660 MW 256 568/596 2008

800 MW 256 568/596 2008



Type of boilers

Drum type

- for sub-critical parameters

Once-through type - for sub/super Critical Parameters



Drum type boiler

Steam generation takes place in furnace water walls Fixed evaporation end point - the drum Steam -water separation takes place in the drum Separated water mixed with incoming feed water



Types of Circulation



Drum type boiler

Natural Circulation Boiler

Circulation thru water walls by thermo-siphon effect

Controlled Circulation Boiler

At higher operating pressures just below critical pressure levels, thermo-siphon effect supplemented by pumps



Natural Circulation Controlled Circulation



Pressure range

Sub critical : Below 221 bar

Super critical : 221 bar and above

What is Super critical pressure ?



SC Steam generator

Boiler Steam Pressure above the critical point Critical Point

221 bar, 374 º c

S

T

1

2

3

4

Entropy

Tem

per

atu

re

1 - 2 Feed Water Pumping Process 2 - 3 Heat addition in the Feed

Water Heaters & Boiler 3 - 4 Expansion in HP Turbine 4 - 5 Reheating in Boiler 5 - 6 Expansion in IP & LP Turbine 6 - 1 Heat rejection in Condenser

5

6



Supercritical Boilers

Supercritical pressure boiler has no drum and heat absorbing

surface being, in effect, one continuous tube, in which the water &

steam generated in the furnace water walls passes through only

once 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.



The Concept

The mass flow rate thru’ all heat transfer circuits from Eco. inlet to

SH outlet is kept same except at low loads wherein recirculation is

resorted to protect the water wall system



Increased mass flow through spiral waterwall tubing, or improved heat transfer through rifled vertical wall tubing.

No fixed evaporator end point

No thick wall components

Features

Once Through Boiler Flow Diagram

Evaporator

Water separator

Feedwater

Economizer

FW-Pump

Live steam

Superheater



Supercritical Boilers- Major Systems



General Arrangement of Steam Generator – Elevation



General Arrangement of Steam Generator – Plan



Once through Supercritical Boilers

Major differences from Drum type boiler :

Evaporator system

Low load Recirculation system

Separator



STEAM TO TURBINESTEAM TO TURBINE

SHSH

DRUM

SEPERATINGVESSEL

EVA

POR

ATO

R

EVA

POR

ATO

R

ECO.

ECO.

(LOW LOAD &CIRCULATION PUMP

START-UP)

FEED

FEED

CIRCULATION TYPEASSISTED

Circulation Systems

Drum Type Once-through



Once -through Operating Range



Once -thru Boiler

Requirements :

Stringent water quality

Different control system compared to drum type

Low load circulation system

Special design to support the spiral furnace wall weight

High pressure drop in pressure parts

Higher design pressure for components from feed pump to separator



Features of Once Through Steam Generator

To ensure adequate mass flow rates through water wall, spirally wound water wall tubes are used.

Start-up and low load system up to 30-40% BMCR required.

Feed water quality requirements are very stringent.

Can be designed for both sub-critical and super-critical pressures.

Ideally suited for sliding pressure operation due to the absence of thick walled components.



Once -thru Boiler

Evaporator system :

Formed by a number of parallel tubes

Tubes spirally wound around the furnace to reduce number of tubes and to increase the mass flow rate thru’ the tubes

Small tube diameter

Arrangement ensures high mass velocity thru the tubes



· Reduced number of tubes with pitch.

· Increased mass flow.

· Mass flow rate can be selected by number of tubes.

Features

Spiral Tube Arrangement



Once -thru Boiler - Furnace Wall



Spiral Water wall Tubing

Lateral Heat Flux Profile



Sliding Pressure Supercritical Design

Spiral Wall Windbox



SPIRAL WALL SUPPORT

Support Fingers

Spiral to Vertical Transition Area - Load Transfer

Sliding Pressure Supercritical Design



Furnace Wall Designs

Spiral Wall Configuration Vertical Wall Configuration



Supercritical Boiler with Vertical wallUnit Mwe: 750

Max. Continuous Rating: 2522 t/h

SH Outlet Press: 262 bar

SH Outlet Temp: 568°C

RH Outlet Temp: 596 °C

Fuel: Sub-bituminous



SCREEN TUBESSMOOTH TUBING

FRONT WALLRIFLED TUBING

SMOOTH TUBINGFROM THIS ELEVATION

ALL WALLS

SIDE WALLRIFLED TUBING

REAR WALLRIFLED TUBING

ARCHRIFLED TUBING

HANGER TUBESSMOOTH TUBING

FRONT WALLRIFLED TUBING

SIDE WALLRIFLED TUBING

Vertical Wall Sliding Pressure Supercritical Design



Vertical Furnace Wall Design

Vertical tube furnace walls will provide all the operational benefits

of the currently popular spiral design while significantly reducing

the cost and construction time for the furnace and providing some

reduction in pressure drop.



Vertical Wall Design - Advantages

The tubes are self supporting.

Transition headers at spiral/vertical interface are avoided.

Ash hopper tubing geometry simplified

Corners are easier to form

Reduced pressure drop, auxiliary power



Spiral Vs. Vertical Wall Comparison

• Spiral Furnace System Applicable for all size units

• Benefits from averaging of lateral heat absorption variation (each tube forms a part of each furnace wall)

• Simplified inlet header arrangement• Large number of operating units• Use of smooth bore tubing throughout

entire furnace wall system• One material utilized throughout entire

waterwall system• No individual tube orifices – Less

maintenance & pluggage potential

• Vertical Furnace Wall System Limited to larger capacity units .

• Less complicated windbox openings• Traditional furnace water wall support

system• Elimination of intermediate furnace wall

transition header• Less welding in the lower furnace wall

system• Easier to identify and repair tubes leaks• Lower water wall system pressure drop

thereby reducing required feed pump power



Vertical Wall Wind box

Straight Tubes

Only a Few Bends at the Top and Bottom



Supercritical Boilers- Start-up andLow load recirculation Systems



Low load system with circulating pump



Once -thru Boiler

Separator :

• Separates steam and water during the circulating mode operation

• Runs dry during once-thru flow mode

• Smaller in size compared to drum in a drum type boiler



Start-up System



Overview of Firing Systems

Close-CoupledOverfire AirClose-CoupledOverfire Air

CFS Air Nozzle TipsCFS Air Nozzle Tips

Flame AttachmentCoal Nozzle TipFlame AttachmentCoal Nozzle Tip

NOx < 0.18 – 0.30 kg/Mkcal*NOx < 0.18 – 0.30 kg/Mkcal*

Furnace DiagonalFurnace Diagonal

Separated Overfire AirSeparated Overfire Air

HP Pulverizerwith Dynamic Classifier

HP Pulverizerwith Dynamic Classifier

*NOx at furnace outlet



Wind Box arrangement



Upper SOFA on Walls

Lower SOFA in Corners

Tilt +/-30o

Yaw +/-20o

Plan View for SOFA arrangement



Materials in 660 MW (Typical)



Pressure part 660 MWOTSC (Supercritical)

500 MW(Sub-critical)

Drum Not applicable SA 299 (Carbon Steel)

Vertical Separator SA 335 P91 Not applicableWater Walls SA 213 T22 SA 210 Gr CEconomiser SA 210 Gr C Sa 210 Gr C

SH T91, TP 347H T11/T22/T91/ TP 347H

RH T12/T23/T91/TP347H/ Super 304H T22, T91, TP 347H

Material Comparison



Boiler Parameters

Description Unit 660 MW (Supercritical)

500 MW (Sub critical)

Boiler Parameters - BMCR BMCR

SH steam flow t/h 2120 1625

SHO pressure kg/cm2(a) 256 179

SHO/RHO temp. oC 568/596 540/540

Feed water temp. oC 294 254



Description (Source/Type)

Unit Design Coal Worst Coal Best Coal

Proximate AnalysisFixed Carbon % 26.00 23.00 32.00Volatile matter % 19.00 18.00 22.00Moisture % 15.00 17.00 12.00Ash % 40.00 42.00 34.00Total % 100 100 100HHV kcal/kg 3300 2800 4000Ultimate AnalysisCarbon % 31.37 28.93 40.08Hydrogen % 3.40 2.40 3.50Sulphur % 0.40 0.5 0.36Nitrogen % 1.5 1.45 1.78Oxygen(difference) % 7.75 7.26 8.03Moisture % 15.0 17.0 12.0Ash % 40.0 42.0 34.0Carbonates + Phosphorous % 0.58 0.46 0.25Hard Grove Index 55 50 60

Fuel Analysis - Coal



General Arrangement of Steam Generator – Plan



ULTRA SUPER CRITICAL TECHNOLOGY&

ADVANCED ULTRA SUPER CRITICAL TECHNOLOGY



The Basic Heat Cycle

Sub-critical units: Main steam pressure < 221. 1 barSuper-critical units: Main steam pressure > 221. 1 bar

Ultra-supercritical units:Higher steam pressure and temperature than supercritical units

Japan: Main steam pressure >242 Bar, or Steam temperature >593 ℃

Demark: Main steam pressure >275 BarChina: Main steam pressure >270 BarUSA (EPRI) : Main steam temperature>593 ℃



• Plant with steam pressure exceeding 225 kg/cm2 is said “Supercritical”

• Supercritical plant with main steam temperature 600C is said “Ultra Super-Critical”

• Supercritical plant with main steam temperature 700C is “Advanced Ultra Super-Critical

STEAM PARAMETERS



Evolution of Steam Power Stations Efficiency Worldwide

64ADVANCED USC TECHNOLOGY28 August 2012

EUROPEAN PERSPECTIVE AND ADVANCEMENT FOR ADVANCED USC

Pulverised Fuel-importance in World Power Generation

Background of Development Of USC Plant with Steam Temperature around 600 0C

Immediate Possibility of going to 650 0C & 700 0C with Nickel Alloy

Best Strategy for reduction of CO2 Emission


AD700 TECHNOLOGY

USC steam parameters-700 0C and 350 bar

This can be achieved only by using Nickel based alloys

In July 2005 :COMTES 700 testing most important components – started operation in power plant Scholven in Gelchen-kirchen

Completed in 2009. During operation phase, valuable operational experience and processing technical knowledge were gained

Welding of thick walled materials must be improved

More test needed for improved welding techniques for 617 or Alloy 740 or Nimonic 263


Japanese programme 2007 & 2008 (finding out and stabilising the structure parameters affecting creep strength and degradation for accurately estimating 1,00,000 hr creep strength)

New alloys

Fundamental studies on creep strength degradation assessment needed to ensure long term safe use.(FS->650 0C AS ->700 0C Ni-> 750 0C)

FS->100 MPa @ 650 0C beyond 30000 hrs without any type IV degradation

AS->generated by means of inter metallic compound precipitation strength grain boundary, strongest creep.

R&D PROGRAM FOR A-USC MATERIAL DEVELOPMENT WITH CREEP STRENGTH/DEGRADATION ASSESMENT STUDIES


USC POWER PLANT DEVELOPMENT IN JAPAN


METI/NEDO MATERIAL R&D PROGRAM


China first established use with parameters 600 0C/25 MPa in 2006

TP347FGH & Super304H

GH984, Nimonic 80A

Ni-Cr-Co Inconel 740 studied with Special Metal Corp. USA for steam temperature of 700 0C

STRUCTURAL STABILITY STUDY ON USE POWER PLANT ADVANCE HEAT RESISTANCE STEELS AND ALLOYS IN CHINA


A cost effective CO2 emission reduction option

Engineering design study(EPRI)

Cost and performance of USC with conventional coal power plants

Slightly more expensive

Cost of avoided CO2 emission was less than $25 per metric ton of CO2 capture and storage

ECONOMIC ANALYSIS (EPRI)


• STEAM SIDE OXIDATION

• FIRE SIDE CORROSION

• CREEP STRENTH

MATERIAL SELECTION


GKM TEST RIG


Strengthening and degradation of long term creep properties and the relevant microstructural evolution in advance high Cr-Ferritic steels and Austenitic steels at high temperature

GKM TEST RIG

Investigation of the long term operation behaviour tubes and forgings made of alloys for future high nuclear power plants

Qualification of key materials for 700°C fossil fuel power plant

Demonstration of material performance with special consideration of oxidation and corrosion behaviour

Creep damage development

Early detection of damage in new material in connection with advance calculation tools for components

ADVANCES IN MATERIAL TECHNOLOGY


ADVANCE CONCEPT FOR MAINTANENCE AND REPAIR FOR COMPONENTS MADE OF NEW MATERIALS

SH Test Track

Creep Test Track (upto 630 °C Austenite steel & upto 725 °C Ni based alloys)

Monitoring devices for evolution of ongoing damage

ADVANCES IN MATERIAL TECHNOLOGY


BY SPECIAL METALS CORPORATION

Developed for operating with 700°C steam temperature and higher pressure.

EUROPEAN TARGET

Stress rupture requirement of 1,00,000 Hrs rupture life at 750°C and 100 MPa stress.

Metal loss of less than 2 mm in 2,00,000 hrs of Superheater service.

DISADVANTAGE OF INCONEL ALLOY 740

Thick section fabrication posed weldability challenges.

Grain boundary microfissuring occurred in the heat affected zone (HAZ) of the base metal.

OPTIMIZATION OF INCONEL ALLOY 740

7828 August 2012 Advanced USC Presentation

BHELDevelopment, Design &

Manufacture of Power Cycle Equipment, System Engineering,

Test Facility and Evaluation

NTPCDetailed Project Report

Project ManagementOperation and Maintenance

Testing of Real Life Components in an existing plant

IGCARAdvanced Design Analysis

Materials DevelopmentManufacturing Technology

Testing and Evaluation

800 MWeAdvanced

Ultra Super CriticalPower Plant

MoU&

Synergy

Robust Roadmap for Success of MissionRobust Roadmap for Success of Mission



Gearing-up to introduce Advanced Ultra supercritical boilers (AUSC)

AUSC Boilers (300 ata, 700 C / 700 C) will be developed based on OTSC technology

Test Facility (400 bar, 700 Deg. C) installed and tests are on to collect critical design data

BHEL is one among the Five MNC’s to have this facility

Member of the National Technology Mission program to install AUSC plant by 2017

Advanced Ultra Super Critical Plants



SUMMARY

OTSC plants offer better cycle efficiency

Proven technologies leading to lower GHG emissions and lesser fuel burnt

BHEL has the technology for offering 660/700/800 MW supercritical units



Thank You

Enhancing Capacity – Empowering Nation Presentation on Supercritical Boilers 28 August 2012.

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Transcript of Enhancing Capacity – Empowering Nation Presentation on Supercritical Boilers 28 August 2012.