development of the 700 c coal power · pdf filedevelopment of the 700 °c coal power plant...

Development of the 700 °C coal power plant

from the perspective of an European utility

4th EU South Africa Clean Coal Working Group Meeting

5 – 6 November 2012, Johannesburg

Gregor Gierschner - E.ON New Build and Technology GmbH

Christian Ullrich - E.ON New Build and Technology GmbH

Helmut Tschaffon - VGB PowerTech e.V.

2

Content

E.ON’s Project 50plus and the Cooperation COMTES+

High Temperature Valves

Repair Concept for thick-walled A617 Pipes

Challenges on the Way to the 700°C Power Plant

Gierschner, 5 – 6 November 2012, Johannesburg 3

Content






Increased Efficiency by the use of Nickel Based Alloys

State of the Art

Future?

600°C steam

46% net efficiency

materials:

martensites and

austenites

700°C steam

50% net efficiency

materials:

nickel based

alloys

Gierschner, 5 – 6 November 2012, Johannesburg

E.ON‘s 700 °C Demonstration Power Plant

Project 50plus (stopped)

Valve casing out of

alloy617 from Hora

Valve casing out of

alloy617B

from Sempell

Net efficiency

Electrical output

CO2-Emissions

Budget

>50 % (LHV)

508 MW

670 g CO2/kWh

>1 bn €

What was done by E.ON?

Selection of plant site and size

Pre and detail engineering

Specifications for components

Offers for 700 °C components

Material research for critical

components with manufacturers

Manufacturing tests of some critical

components

Live steam pipe


Nickel Based Component Test Facilities

COMTES700, HWTII and ENCIO Project

COMTES700

HWTII

ENCIO

Public Funding

European

Commission

(Research Fund

for Coal and Steel)

BMWi

European

Commission

(Research Fund

for Coal and Steel)

Partner

VGB, E.ON, EDF, Electrabel, EnBW, ENEL, DONG,

PPC, RWE, Vattenfall, Alstom, Hitachi, B&W,

Siemens

GKM, ABB, Babcock Borsig Service GmbH, BASF,

BGH, BHR, Böhler, Bopp und Reuther, E.ON,

EagleBurgmann, EnBW, Fraunhofer IWM, RWTH

Aachen, Kraftanlagen München, KSB, Lisega, MPA

Stuttgart, MVV, Saarschmiede, SMST, SLV

Mannheim, IFW Darmstadt, ThyssenKrupp VDM,

TÜV Süd, VGB, V&M, Welland & Tuxhorn, Wrede &

Niedecken

VGB, ENEL, Hitachi, Centro Sviluppo Materiali, CEZ,

EDF, EnBW, ENEL, E.ON, Eskom, EVN, Evonik,

GDF Suez, GKM, RWE, Vattenfall, HORA, Sandvik,

Sempell, V&M, ThyssenKrupp VDM,

VoestAlpine, Siemens, Böhler

CO

MT

ES

+

COMTES+ partners: VGB, ENEL, CEZ, EDF, EnBW, ENEL, E.ON,

Eskom, EVN, Evonik, GDF Suez, GKM, RWE, Vattenfall


Content





Gierschner, 5 – 6 November 2012, Johannesburg Theme Date

700°C Valves from COMTES700:

Experience and Lessons Learned

CO

MT

ES

70

0 h

p b

yp

as

s v

alv

e:

Flo

w t

o C

los

e D

es

ign

(F

TC

)

Planned operation conditions for hp bypass station

100 - 500 h operation time at full load

10 - 20 times operation in bypass mode at maximum

steam conditions

Real operation conditions for hp bypass station

Daily operation of hp bypass station during start-up and

shut-down times from July 2005 to March 2008 due to

changed load profile of the host power plant Scholven F

In addition, full operation from April 2008 to August 2009

(not only start-up and shut-down)

Experience

Full functionality of hp bypass valve given during the

four years of operation

Graphite and metallic gaskets applicable for 700 °C

components in lower temperature area

Only slight but reasonable indications of erosion at

seat area and at throttle bores

But: cracks in the thick-walled valve body

8




perforated

disc

COMTES700

CO

MT

ES

70

0 h

p b

yp

as

s v

alv

e:

Flo

w t

o C

los

e D

es

ign

(F

TC

)

9


Avoidance of small radii and notches

Favouritism of smooth transitions in geometry and good

surface quality

Avoidance of high temperature gradients

Avoidance of welds inside the valve body if possible

Reduction of notch effects and other stress concentrations by

weld design measures and grinding of the weld

Location of welds in areas where thermo mechanical stresses

are low




Avoidance of threads in pressure bearing parts wherever

possible

Avoidance of high notch effects and other stress

concentrations if threads cannot be avoided





T1

T2

T3 F1

live steam pipe

to hot

reheat pipe

hp bypass

High temperature gradient

during start-up in this

example

Gradients lead to thermal

stresses and to a reduction

of life time

High temperature gradients

to be avoided in general

But high temperature

gradients to be avoided

particularly in high

pressure 700 °C

components due to the

thermo-mechanical

properties of nickel based

alloys

0

100

200

300

400

500

600

700

00:0

0

02:0

0

04:0

0

06:0

0

08:0

0

10:0

0

0

10

20

30

40

50

regular

operation hot start down time

°C

T1 (steam)

T2 (steam)

T3 (material)

F1

time

kg/s


Improved design for 700°C valves of A617B

Challenges and Solutions:

high steam temperature gradients can

cause high stresses and cracks →

appropriate preheating design

Residual welding stresses can lead to

relaxation cracking → heat treatment of

welds at 980°C/3h

Valve cover gasket and spindle seal

become ineffective due to high

temperatures → low temperatures in

sealing area

980°C/3h

after

welding

T1

T2

T1~T2

spindle seal

Valve cover

gasket


hydraulic cylinder

steam assisted

water injection

cooling

Inlet: Ø245 x 65

Outlet: Ø168,3 x 10

2.600 kg

HP Bypass Valve for HWTII

The hp bypass valve was

originally designed for the 50+

demonstration power plant with

500 MWel and was adapted for

the 725°C test rig HWTII

A617B

forged

Flow to Open Design

(FTO)

3 stage pressure

reduction with

parabolic plug

containing 2

concentrical cages

graphite stem

packing


Adaption of the Seat to the new Requirements

The diameter of the seat had to be

reduced from Ø 105 mm to Ø 25 mm

due to the reduced flow rates

The reduction was realised with a

build-up weld

PT test of build-up weld

build-up weld at seat


HP Bypass Valve for

HWTII after Manufacturing

and during Installation in

GKM Power Plant

28

10

mm


Content






Repair Welds in COMTES700 Test Facility

weld

HAZ

HAZ

cracks in the HAZ of repair welds were

observed

a workable solution was not reached

during the operation time of

COMTES700

repair weld, A617 steam pipe,

220x50mm, 20kh operation

Cracks in heat affected zone (HAZ)

COMTES700 COMTES700


New solution annealed A617B

Solution annealed condition shows some Cr-Carbides at the grain boundaries

Inside of the grain generally free of precipitations apart from primary precipitations

SEM TEM

100nm100nm20μm


Service exposed A617B after 700°C/22kh

In service exposed material Cr-Carbides at the grain boundaries and inside

the grain are found

Formation of ‘ inside the grain

100nm 20µm

SEM TEM

’

Carbid


COMTES700 Welding Tests

Ele

ctro

de

Mech

an

ize

d T

IG

98

0°C

/3h

HT

befo

re w

eld

ing

1160

°C

So

lutio

n

An

nealin

g

Weld 1 X

Weld 2 X

Weld 3 X X

Weld 4 X X

Weld 5 X X

Weld 6 X X

welding procedure

Influence of …

heat treatment

of base material

before welding

Heat treatment after

welding in any case

(980°C/3h)


Influence of The Weld Technique

26 mm 12 mm

50 m

m

Electrode weld Mechanised TIG weld

COMTES700 COMTES700

The bead sequence and the heat input is more homogeneous in the

case of TIG orbital welding

Mechanised TIG leads to a significant reduction in weld size.

Internal stresses are reduced.


Influence of Heat Treatments on Service Exposed Material

’ precipitates can be solved with 980°C / 3h heat treatment

Carbides being present can not be solved either by 980°C / 3h nor 1160°C / 1h.

But their number and size change significantly at 1160°C

A617B service exposed (22kh) A617B service exposed (22kh)

plus 980°C / 3h

A617B service exposed (22kh)

plus 1160°C / 1h

’ Carbid Carbid Carbid

100nm


400 m400 m 400 m400 m

Electrode Weld:

Service exposed

+ 980°C/3h Pre-Weld-Heat-Treatment

Electrode Weld:

Service exposed

without Pre-Weld-Heat-Treatment

Electrode Weld:

Service exposed


400 m400 m

Weld 1 Weld 3 Weld 5

TIG Orbital Weld:

Service exposed


TIG Orbital Weld:

Service exposed


TIG Orbital Weld:

Service exposed


400 m400 m400 m400 m400 m400 m


400 m400 m 400 m400 m

Electrode Weld:

Service exposed


Electrode Weld:

Service exposed


Electrode Weld:

Service exposed


400 m400 m


400 m400 m 400 m400 m

Electrode Weld:

Service exposed


Electrode Weld:

Service exposed


Electrode Weld:

Service exposed


400 m400 m


980°C/3h Pre-

Weld-Heat-

Treatment

1160°C/1h Pre-

Weld-Heat-

Treatment

Without Pre-Weld-

Heat-Treatment

TIG Orbital

Weld

Electrode

Weld

Results of COMTES700 Welding Tests

Mechanised TIG welds show better results than Electrode welds

The heat treatment of the base material prior welding has a

significant influence. No defects could be observed in the HAZ in

case of 1160° annealing


Content






43

44

45

46

47

48

520 570 620 670 720

η

C

Plant Efficiency and Price of Nickel Based Alloys

Material price based

on trade prices for

elements (18.07.2012)

Melting and processing to

pipes, round bars,…

NiBa Alloy

54% Ni

21% Cr

11% Co

09% Mo

Martensite

87% Fe

09% Cr

02% W

0.5%Mo

Ferrite

97% Fe

01% Cr

0.5% Mn

0.5% Mo

Raise of efficiency more or less

proportional to temperature in the

considered range

Raise of price exponential to

temperature

Price for nickel based alloy might

decrease for large scale application

Cost for subsequent processing

(turning, milling,…) higher in

comparison to martensitic steels

250 bar

540 °C

540 °C

270 bar

580 °C

600 °C

285 bar

600 °C

620 °C

300 bar

625 °C

640 °C

300 bar

700 °C

720 °C

Data Source: Power Generation from Solid Fuels – H. Spliethoff

0

25

50

0

25

50

550 °C

0

25

50

620 °C

0

25

50 725 °C €/kg

25

0

price for small scale

application

possible price for

large scale application

25


Flexibility Goals of Power Plants

Load

MW

0

Min.

Max.

minimum

min. load

minimum

start-up time maximum load

gradients

minimum shut-

down time

increased

number of starts

minimum

downtime

Time

26

Gierschner, 5 – 6 November 2012, Johannesburg Theme Date 27

9

11

13

15

100 300 500 700

Temperature in °C

Mean C

oeffic

ient

of

linear

Expansio

n in 1

0-6

/K

10

20

30

40

100 300 500 700

Temperature in °C

Therm

al C

ondu

ctivity

In W

/(m

K)

Lower thermal conductivity of nickel based

alloys

slow assimilation of the temperature in a

component

Therefore, higher thermal induced stresses

High thermal expansion of nickel based alloys

Higher thermal induced stresses in case of local

temperature differences

Operation Flexibility of Nickel Based Alloys

The behaviour of nickel based alloys in terms of thermal flexibility has to be

investigated in detail

The current projects have to show that nickel based components fulfil the

flexibility requirements of the future

martensitic steel

nickel based alloy

martensitic steel

nickel based alloy

pipe during

start-up

hot

cold


Theme Date


and Conclusions

Technical

There are still some technical questions on the way to the 700°C power

plant.

The technical risk for the erecting of a 700°C demonstration power

plant has to be minimised by the projects HWTII and ENCIO.

Financial

The costs for nickel based alloys and its machining is much higher than

for conventional materials.

The price for nickel based components has to be reduced among

others by novel manufacturing methods which will be tested in

COMTES+.

Flexibility

Increased flexibility capability is needed in Europe due to the increasing

influence of renewable energy production.

From the first point of view, nickel based alloys do not have good

characteristics in terms of thermal flexibility. COMTES+ will give an

answer to that question.

28


Thank you for your attention

and special thanks to all partners of

COMTES700 and COMTES+, which were

involved in some of the presented

activities as well as to the funding of

BMWi and the Research Fund for Coal

and Steel of the European Commission

In Zusammenarbeit mit: Gefördert durch:

29

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