super - critical boiler technology

Bharat Heavy Electricals Limited, Tiruchirapalli

SC Boiler Technology : 11th Dec 2007

Super - Critical Boiler Technology

By

C.JayadevanGeneral Manager

Engineering/Fossil BoilersBharat Heavy Electricals ltd., Tiruchirappalli



Indian Power Scenario

Installed Generation Capacity – current : 130 000 MW

Capacity Requirement by 2012 : 200 000 MW

Capacity Addition – XI plan programme : 78 000 MW

New Capacity Additions include

Ultra Mega Power Plants (UMPP) – Capacity 4000MW each



Market Requirements

Low cost of generation Minimum emission of PollutantsSuitability for different quality of fuelSuitability for differing modes of operation/ grid conditionsHigh Reliability & AvailabilityIncreased use of IT Lowest life cycle cost Life Extension of Power Plants & capacity upgradesHigher size UnitsShorter Delivery time

Bharat Heavy Electricals Limited TIRUCHIRAPALLI

Presentation to CII, JULY 2004

Power Plant Equipment Manufacturers to respond by

Upgrading the technologyImproving the efficiency Reducing the cost



Major share of the current energy produced from fossil fuels. Dependence on petroleum fuels reduced world overCoal to continue as mainstay of power generation• abundant availability• relatively lower cost • maturity level of technology options

Energy Options



Boiler Technology - Advances in the last Century

SizeSteam ConditionsMaterialsControls & InstrumentationEfficiencyAvailability& ReliabilitySafetyOperational Ease

High Pressure Boilers Vital Component of Coal based Power Generation



Boile

r Cap

acity

in M

W

2 10 M W To w e r Typ e

Y e a r1960 1970 1980

200 M W

Ta n g e n tia l F irin g110 M W

0

100

W a ll F irin g60 M W

120 M W

200

300

210 M W

20001990 2010

250 M W

C o n tro lle dC irc u la tio n

500 M W

400

500

600

O n c e Th ro '500 M W

Growth of Unit Size in India

660MW –800 MW sizes being inducted



Steam Power plant efficiency increases with increase in steam pressure and temperature.

Power plant Cycles operating above critical pressure (221.2 bar) are classified as Supercritical cycles

With higher cycle efficiency, the supercritical cycle offers the advantage of‘burn less fuel for the same output’ and lower emission.

Supercritical Cycles

Lesser Pollutants – SOX , NOX & CO2



2.0

1.5

0.4

0.7

2.0

7.2 %

Turbine Efficiency

Condenser Pressure

Process Optimisation

Steam Parameters

Feed Water Temperature

(FWT, feed heater arrangement)

0.6 Measures on Steam generator

240

- 280

bar

ev

opor

ator

pre

ssur

e55

50

45

40

35

BHEL CC+ Units

Effic

ienc

y, %

20001980 19901960301950 1970

Year

250

bar /

550

°C /

570

°C26

0 ba

r / 5

80 °C

/ 6

00 °C

280

bar /

600

°C /

620

°CBasis 38 %

175

bar /

540

°C /

540

°C

Efficiency Development of power plants in Europe

Efficiency Improvement of Steam power plants

Source: VGB Power Tech 11/2003

Heat Rate Improvement



Heat Rate ImprovementSteam Parameters Vs Cycle Efficiency

300241

175 538 / 538

538 / 566

566 / 566

580 / 600600 / 620

6.775.79

3.74

5.744.81

2.764.26

3.44

1.47

3.372.64

0.75

2.421.78

00

1

2

3

4

5

6

7

8

9

10

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

Increase of efficiency [%]

Cycle efficiency with :175 bar and 538/ 538 ºC = 38.0 % (BASE)241 bar and 538/ 566 ºC = 38.0 x 1.0264 = 39%



Station Cap

(MW)

Units(No.x MW)

MS Pressure (kg/cm2)

MS/RH Temp 0C

Efficiency (%)

Coal Consumption

(MMT/Yr)

CO2Emissions (MMT/Yr)

4000 8x500 169 538/538 38.6 15.61 22.90

4000 5x800 246 566/593 40.24 14.98 21.97

Environmental Benefits

Source : CEA

Savings in Coal consumed : 0.63 MMT/Yr (about 4% Saving)Savings in CO2 emissions : 0.93 MMT/Yr



Super-critical cyclesfor

Thermal Power Generation

Higher cycle efficiency for :

Conservation of fuel resourcesReduction of Pollutants - SOX & NOX

Reduction in CO2 emission Better economy in power generation where fuel costs are high and pollution control requirements are stringent



Population of 800 to 1000 MW Unitsinstalled worldwide

USA Japan Russia Germany South Korea China Ukrai

neUzbekis

tan

35 21 19 5 3 3 2 1

Total Units = 89

Coal Fired = 54



Steam Parameters - commonly used:

MS Pressure : 247 ata

MS Temperature : 565 OC

RH Temperature : 593 OC

Power plants with Ultra Supercritical steam parameters 350 bar / 700 OC / 700 OC and Net efficiency 50%

under development



DRUM TYPE Vs ONCE THRU’ BOILERS

Drum Type

Subcritical Pressure

Once thru

Supercritical pressure



VERTICAL TYPE

SPIRAL TYPE

Supercritical Boiler Supercritical Boiler Furnace Wall ArrangementFurnace Wall Arrangement



Supercritical Boilers – demands on materials

Demanding service conditions - in terms of sizes, steam conditions, operating requirements etc.

Super critical pressure and the high temperatures stress the boiler components at a high level.

Choice of materials - prime importance with higher steam parameters.

Realising higher steam parameters dependent, on the availability of materials to withstand the

demanding service conditions.



Strength to resist rupture at design condition

Fatigue strength to withstand cycling stresses

Ability to resist stress concentrations

Resistance to oxidation,corrosion and erosion

Ability to withstand damaging metallurgical changes during operation

Ease of fabrication

Ease of field construction and maintenance

Physical properties to minimise thermal stresses

Materials for Supercritical Boilers - Properties



Materials for Supercritical Boilers

New materials developed in the last two decades to suit high steam parameters

Optimised to achieve greater long-term rupture strength, improved resistance to high temperature corrosion and lower oxide film growth.

Bridge the gap between the ferritic steels and austenitic steels - make the boilers economically viable.

New Materials in use/ under evaluationT92/P92, T23/P23, Super 304H , TP 347HFG , Alloy 617, AC66,

Esshete 1250, HR 3C, NF 709, Incoclad 671, Alloy 617



Coal Quality Impact on Boiler Economics & Performance

Indian coals - generally high ash , low calorific value - Warrants bigger equipment -boilers, auxiliaries, coal & ash handling systems

- Increased maintenanceWashed coal / imported colas also now being used by some UtilitiesBoiler design for firing a wide range of coals – increase in cost & likely compromise on performance Close band of properties - improves the boiler performance and reduces the overall cost of power generation. Use of consistent quality better coals/ washed Indian coals/blending with imported coals to achieve close band



Technologies - to be targeted at achieving higher efficiency and cost effectiveness

Coal based thermal power generation will continue to be the mainstay

Pulverised coal firing – ahead in technical development and operational experience over new technologies

Supercritical technology

facilitate use of coal in economic & eco-friendly mannerthe technology of future in India for large capacity units.

Conclusion

Boiler Manufacturers & Utilities to make use of the boiler technology

in the most efficient and environmentally friendly manner

Bharat Heavy Electricals Ltd; Tiruchirappalli

super - critical boiler technology

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