attachment 10 - milan conference 2005

7/31/2019 Attachment 10 - Milan Conference 2005

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Alstom Steam Turbine Designs for

AD700 Power Plant

Andreas Pirscher

(Alstom Power)


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ALSTOM (Switzerland) Ltd 2005 Preliminary/for discussion purposes only. We reserve all rights in this document and in the information contained therein. Reproduction, use or

disclosure to third parties without express authority is strictly forbidden.

Alstom Roadmap for >700C Turbines

Material Development / Testing

Testing of materials and

components (forged, cast and

welded)

Component testing (COMTES)

Demonstration turbine

Advanced high temperature turbine

Design .

First design concepts

Emax design and additional internal studbased on proven technology with some

high temperature specific features

Further develop design concepts

Detailed design based on proven

technology

Develop advanced designs to furthe

reduce Nickel base alloy weight and

reduce transient stresses to improvestart up times

1998

2005

2010

2015


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Alstom Concept

400 MW Single Reheat (1/2)

GLP1 LP2IP

HP

426 C

720 C

263 C700 C


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Alstom Concept

400 MW Single Reheat (2/2)

Thermodynamic calculations

Steam path designed with standard Alstom design tools using hightemperature materials

Blade material nickel base alloy, austenitic steel, 12% Cr steel

Rotordynamic feasibility


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Rotor Design: Welded Rotor (1/7)

Alstom has over 70 years experience in in rotor weld technology Several thousand welded rotors in operation

Not a single case of a ruptured welded rotor

Excellent material testing conditions, good access for ultrasonic testing Alstom methodology of designing rotor welds heavily depends on the

large fleet experience

therefore it is possible to design new rotor welds based on laboratortesting and analysis by reading across from existing rotor welds

validated in the Alstom fleet


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Advantage: Lower stresses in welded rotor compared to monoblock rotor Example: Cold start of an HP rotor:

Monoblock rotor with center bore 500 N/mm2 200 N/mm2

250 N/mm2 500 N/mm2

Welded rotor 150 N/mm2 300 N/mm2

200 N/mm2 300 N/mm2


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Optimal design for very high temperature applicationWelding technology allows the application of the appropriatematerial where needed

Nickel base alloys for very high temperatures > 620C

(Not shown in the picture, which is only for illustration)

9-12 % Cr steel for high temperatures > 540 C

1-2 % Cr steel for steam temperatures < 540 C1-2 % Cr low yield strength steel for low pressure applications


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9

10

11

12

13

14

15

16

17

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750

Te mpe ra ture (C)

617

1%CrMoV

St10TS

Specific design aspects for rotor welds with nickel base alloys Limitation on ultrasonic inspection

Different thermal expansion coefficients


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Design solutions (1/2) Rotor bridge with two welds

Color codes: Temperatures in C

Nickel base alloy

10% Cr steel


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Design solutions (2/2) Weld between the nickel alloy and 1 2 % Cr steel

Almost cost neutral to design solution 1

Nickel base alloy1% Cr steel

Move the bridge and the two welds by 3 4

blade stages ( 300 mm) to the cooler end


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In the course of the AD700 project successful test welds were carriedout at Alstom

Full scale test block weld between alloy 617 and 10% Cr steel Full scale test block weld between alloy 625 and 10% Cr steel

(A nickel alloy was used as weld metal in both cases)


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HP Casing: Shrink Ring Design

10 % Cr steelNi base alloy

Shrink ring design used by Alstom since 1960 Excellent design for very high temperatures

Very low casing distortion

Relatively thin structure allows good transient behavior


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HP Casing: Shrink Ring Design

IP Casing: Conventional Alstom Design


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IP Casing: Conventional Alstom Design

Using Nickel Base Alloy

Ni base alloy10 % Cr steel


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COMTES Valve (1/2)

Valve identified as one of the essential components of a 700C turbose The valve has therefore been chosen for the COMTES 700 test with rea

steam conditions loading

The selected valve type is a full-scale main steam control valve Common design of Siemens and Alstom

Crucial test results: Coatings for functional and sliding surfaces, e.g.

between spindle and bushes Results will be transferable and relevant for products of both suppliers


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COMTES Valve (2/2)

Alstom Supply: Yellow, Red

Siemens Supply: Blue

Ad d D i F t


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Advanced Design Features

First demonstration plant will be a base load machine with relativelyfew starts per year. The design concept will be based on the proven

conventional Alstom design with some modifications to allow for the

very high temperatures

In order to design a more flexible turbine with faster start up times for

very high temperatures the following design features are available.

Various features are in the concept phase (patents pending)

Double wall valves (see next slide) Cooling concepts

Multiple shell casings

Improved pre-heating of the turbine Heat shield concepts

E l D bl W ll V l


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Example: Double Wall Valve

25.0 MPa

700 C

17.5 MPa

565 C

Nickel base alloy

9 10 % Cr steel


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attachment 10 - milan conference 2005

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