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Transcript of ultra super technology
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New Generation StrategyUltra-Supercritical
Technology
New Generation StrategyUltra-Supercritical
Technology
Presented by:
Tim Riordan, Manager
New Generation Design & Eng.
APP Site VisitOctober 30 November 4, 2006
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AGENDA
Power Plant Steam Cycle (Rankin Cycle)
History of Supercritical Units
Ultra-supercritical (USC) Overview
AEP Ultra-supercritical DesignSteam Generator Design
Turbine/Generator Design
Efficiency and Emissions Comparison
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SCR NOx control addedto meet NOx SIP Call.Additional NOx controlgreater than 85%
FGDS to reduce SO2 by
greater than 90%
Low NOx Burners.NOx reductiongreater than 50 %
Bag filter to remove Particulate
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Critical Point 3208psi/705F Sub-Critical Steam Cycles : Water boiling to steam
with pressures below critical point
Super-Critical Steam Cycles: Water to steam withoutboiling. Pressure above critical point
Ultra-Supercritical Steam Cycles: Steam temperatures
above 1100 F as defined by Electric Power ResearchInstitute (EPRI)
The Basic Heat Cycle
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Gaining Efficiency
Higher Pressure and Temperature
Power Plant CycleImprovement from Higher Steam Temperature
Entropy
Temperature
1'
Increase in Heat input: b'-3'-2'-2-3-b-b'
Increase in Work: 3'-2'-2-3
Net increase in cycle efficiency
a
1
2
3
b
2'
3'
b'
Critical Point
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The Evolution Continues
Comparison
Entropy
Temperature
Ultra Supercritical
1940 Vintage Subcritical
Non-Reheat
Early 20th Century Vintage
Subcritical Non-Reheat
1960 Vintage
Subcritical Reheat Supercritical
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History of Supercritical Units
First Supercritical Unit: AEP Philo Unit 6
Initial Operation Date: 1957 (49 years ago)
125 MW
Steam Conditions: 4500psi/1150F/1050F/1000F
(double-reheat)
World-wide Over 200 units
Typical steam pressures: 3350 to 4200 psiTypical steam temperatures: 1000 to 1050F
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What is USC Technology?
Defined by EPRI as Rankin Cycle steam temperatures
above 1100F
Limited to ASME code approved metallurgy for pressure
part design
Higher temperatures increase cycle efficiency
USC technology is most efficient cycle available for selected
fuels (sub-bituminous coal)
Higher efficiency = Less emissions
IGCC is limited for sub-bituminous coal applications
Generating Technology:
Ultra-Supercritical (USC) Pulverized Coal Plants
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Generating Technology:
Ultra-Supercritical (USC) Pulverized Coal Plants
An ultra-supercritical (USC) steam generation unit operates at
supercritical pressure (typically 3500 psi or higher) and at
steam temperatures above 1100o
F (593o
C). For comparison, a conventional supercritical unit operates
at steam temperatures of 1000-1050oF (538-566oC).
Modern chrome and nickel-based super alloys in the steam
generator, steam turbine, and piping systems canwithstand prolonged exposure to this high temperature
steam.
By operating at elevated steam temperatures, the turbine
cycle is more efficient. This reduces fuel (coal) consumption,
and thereby reduces emissions.
USC technology is compatible with all types of coal.
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Steam Generator Cross Section
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AEP USC Steam Generator Design Conditions
Pulverized Coal-fired Benson Cycle, Spiral-wound Boiler
PRB Coal
Main Steam: 3675 psi/1115 F
Reheat Steam: 1130 F
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USC Impact on Steam Generator
High Temperature Oxidation
Internal oxidation of boiler tubing above 1050oF
Exfoliation of oxide layers leads to tube pluggage and
could damage turbine blading.
SA-213-T91 material not used in heat transfer zone
Approaching limits of dissimilar metal weld (DMW) designs
DMW Design Limit = 1150oF
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Steam Generator Materials of Construction
SSH Outlet Bank: SA-213-347 HFG Stainless Steel
RH Outlet Bank: SA-213-347 HFG Stainless Steel
Superheater Headers : SA-335 P92
Other alloys typical of previous supercritical designs
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Steam Turbine/Generator
Current Turbine Design for AEP USC Unit:
Four-casing, 3600 RPM, Tandem Compound, Single
Reheat
Single-flow High-pressure (HP) turbine section
Double-flow Intermediate-pressure (IP) turbine section
Two (2) Double-flow Low-pressure (LP) turbine sections
Designed for full arc, sliding pressure operation
Improved Efficiency
Minimize Component ThermalFatigue Damage
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Steam Turbine/Generator
Generator Design for AEP USC Unit:
Two-Pole, Three-Phase Synchronous Machine
840 MVA Rating
Direct Hydrogen cooled field and stator core
Direct water cooled stator windings
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USC Impact on Turbine
Higher operating temperatures call for improved materials of
construction:
Most important components:
Forgings (rotors)
Castings (casings)
Piping
Material Requirements to handle USC operating conditions:
High creep rupture strength
Resistance against embrittlement
Low oxidation growth and no loosening of oxidation layer
Ease in manufacturing and availability
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Turbine Materials of Construction
Main Steam and Reheat Steam Piping: SA-335-P92
Main Steam Valve Casing: 9Cr (CB2)
HP Inner Shell: 9Cr (CB2)
HP Rotor: 9Cr (FB2)
HP Rotating Blading Inlet Stages: Nimonic (Ni80TiAl)
Nickel-based alloySuperior to steel alloys at temperatures above 1050oF
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Efficiency and CO2Emissions Comparison
CO2 Emissions vary
with Heat Rate & Coal Rank
0.85
0.90
0.95
1.00
1.05
1.10
8500 9000 9500 10000 10500
Net Unit Heat Rate (Full Load), Btu/kwh
CO2Emissions
,Tons/MWH
Bituminous
Sub Bituminous
Lignite
Figures for Supercritical and Subcritical are for
existing units w /environmental control retrofits.
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1.06 T/MWh0.99 T/MWh1.03 T/MWh0.97 T/MWhCO2
0.15 lb/MWh0.09 lb/MWh0.15 lb/MWh0.14 lb/MWhPM-10
0.70 lb/MWh0.65 lb/MWh0.68 lb/MWh0.64 lb/MWhNOx
0.99 lb/MWh0.55 lb/MWh0.97 lb/MWh0.91 lb/MWhSO2
Subcritical2400psi/1000F/1000F
IGCC2X1 7FB GT Dry Feed
Supercritical3500psi/1000F/1000F
Ultra SC3800psi/1100F/1100F
Emission
Emission Comparison
Sub-Bituminous Coal
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Conclusion
Ultra-supercritical Pulverized Coal Technology
Higher Temperatures = Better Efficiency
Better Efficiency = Less Emissions and Less Carbon Dioxide
Metallurgy Currently Available for Temperatures above 1100F
Equipment Suppliers Can Guarantee Performance and
Reliability