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New Generation Strategy

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Presentation on theme: "New Generation Strategy"— Presentation transcript:

1 New Generation Strategy
Ultra-Supercritical Technology Presented by: Tim Riordan, Manager New Generation Design & Eng. APP Site Visit October 30 – November 4, 2006

2 AGENDA Power Plant Steam Cycle – (Rankin Cycle)
History of Supercritical Units Ultra-supercritical (USC) Overview AEP Ultra-supercritical Design Steam Generator Design Turbine/Generator Design Efficiency and Emissions Comparison

3 Typical Heat Balance

4 Bag filter to remove Particulate
SCR NOx control added to meet NOx SIP Call. Additional NOx control Low NOx Burners. greater than 85% NOx reduction greater than 50 % FGDS to reduce SO2 by greater than 90% Bag filter to remove Particulate

5 The Basic Heat Cycle Critical Point – 3208psi/705°F
Sub-Critical Steam Cycles : Water boiling to steam with pressures below ‘critical point’ Super-Critical Steam Cycles: Water to steam without boiling. Pressure above ‘critical point’ Ultra-Supercritical Steam Cycles: Steam temperatures above 1100 °F as defined by Electric Power Research Institute (EPRI)

6 Gaining Efficiency Higher Pressure and Temperature
Critical Point

7 The Evolution Continues
Comparison Ultra Supercritical 1960 Vintage Subcritical Reheat Supercritical Temperature Early 20th Century Vintage Subcritical Non-Reheat 1940 Vintage Subcritical Non-Reheat Entropy

8 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 psi Typical steam temperatures: 1000 to 1050°F

9 Generating Technology: Ultra-Supercritical (USC) Pulverized Coal Plants
What is USC Technology? Defined by EPRI as Rankin Cycle steam temperatures above 1100°F 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

10 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 1100 oF (593 oC). For comparison, a conventional supercritical unit operates at steam temperatures of oF ( oC). Modern chrome and nickel-based super alloys in the steam generator, steam turbine, and piping systems can withstand 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.

11 Steam Generator Cross Section

12 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

13 USC Impact on Steam Generator
High Temperature Oxidation Internal oxidation of boiler tubing above 1050 oF 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 = 1150 oF

14 Steam Generator Materials of Construction
SSH Outlet Bank: SA HFG Stainless Steel RH Outlet Bank: SA HFG Stainless Steel Superheater Headers : SA-335 –P92 Other alloys typical of previous supercritical designs

15 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 Thermal Fatigue Damage

16 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

17 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

18 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 alloy Superior to steel alloys at temperatures above 1050 oF

19 Efficiency and CO2 Emissions Comparison

20 Emission Comparison Sub-Bituminous Coal
Ultra SC 3800psi/1100F/1100F Supercritical 3500psi/1000F/1000F IGCC 2X1 7FB GT – Dry Feed Subcritical 2400psi/1000F/1000F SO2 0.91 lb/MWh 0.97 lb/MWh 0.55 lb/MWh 0.99 lb/MWh NOx 0.64 lb/MWh 0.68 lb/MWh 0.65 lb/MWh 0.70 lb/MWh PM-10 0.14 lb/MWh 0.15 lb/MWh 0.09 lb/MWh CO2 0.97 T/MWh 1.03 T/MWh 0.99 T/MWh 1.06 T/MWh

21 Conclusion Ultra-supercritical Pulverized Coal Technology
Higher Temperatures = Better Efficiency Better Efficiency = Less Emissions and Less Carbon Dioxide Metallurgy Currently Available for Temperatures above 1100°F Equipment Suppliers Can Guarantee Performance and Reliability

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