08. Detlef - Alignment&Dummy Cairo

1Cairo, May 2009

Steam Turbine Alignment

©Si

emen

s Po

wer

Gen

erat

ion

2003

. All

Rig

hts

Res

erve

d

May 2009

2

Alignment POWER GENERATION

Introduction

Subject:

Steam Turbine Alignment

Main parts:●

General

●

Steam turbine inner alignment

●

Shaft alignment

●

Modified front end bearing housing

May 2009

3


General

May 2009

4


Internal

/ external

alignment

Internal

alignment:

Ensure

sufficient

internal

clearance

(vertical

/ horizontal)

between

rotor

and stationary

parts

under

consideration

ofCasing deflectionRotor bending lineRotor lifting (approx. 1/3 of bearing Thermal growth clearance)

External

shaft

alignment:Positioning of the rotational centers of the two shafts such that they are co-linear under operating conditions. Reduce dynamic shaft forcesKeep bearing loading normalEnsure thrust bearing parallelity to thrust discEnsure free movement ( sample shoulder bolts horizontal/vertical )Ensure stress free pipe connectionEnsure all fix points are reamed and tight inserted

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Turbine inner alignment

May 2009

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Internal

clearance

Shrouded rotor blade

Stator blade Radial rotor blade clearance

Radial stator blade clearance

Axial blade clearance

Stator

Rotor

May 2009

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Rubbing damage

Unilateral radial gaps

Major alignment deviations

Foundation changes

More than >=2 Guide Blade Carriers installed

Inclination of front bearing housing

Measurement with Alignment shaft

is recommended when ;

May 2009

8


Reason of trust disc damage

High cyclic loading of the disc, which probably caused by

inclination or tilting of the front bearing housing towards the shaft center line

=> In this case a high bending force and moment is acting on the disc

Inclination or tilting of the front bearing housing arise by :

misalignment

high friction underneath the turbine casing paws

hot spot at the foundation between turbine and base frame or bearing pedestal

steam radiation out from the front gland

distension / sliding disability

acting forces and moments from the steam pipes

May 2009

9


Alignment Deviations, samples

-

Setting of foundation

-

Inadmissible external forces (pipings/condenser)

-

Thermal deformations

-

Inadequate sliding behavior of front bearing pedestal

May 2009

10


Internal

Alignment considerations

Static

rotor

deflection

line

Kinetic

rotor

deflection

line

GBC 2GBC 1

GBC 3 GBC 4 + 5

Bearing centre

line

Lower

vertical

position

of GBC 1 + 2

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11


Alignment

shaft

1.

Pick-up

for

bearing

housing

end face and correct

2. Alignment

shaft

placed

in

turbine

lower

half , calibrate,

install top half , assemble turbine casing , tight , take records, disassemble and correct

Measurement

done

at closed

turbine

casing!

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Alignment

shaft

arrangement

Alignment

shaft

supported

at the

front and rear

end bearing

housing.

Pick-up

for

front-end bearing

housing

end face

Weight

for

compensation

of shaft

deflection.Guide-blade carrier

Balance piston

labyrinth

Pick-up

for

rear-end

bearing

housing

end face.

Pick-ups

attached

to the

alignment

shaft

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Casing

RotorSliding elements for vertical position

Bolts for horizontal position

Guide-blade carriers expand freely under the influence of heat without changing their symmetrical position

Guide-blade carrier

Centric guide-blade carrier suspension

Radial gap

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Benefits

The correct adjustment of the radial gaps will minimize the danger of metal to metal contact

No unscheduled outages caused by rubbing

No unprofitable operation of the turbine due to radial gaps enlarged by rubbing

Permanent deformations of the turbine casing are detected and corrective actions can be initiated

No breaking out of babbit metal caused by bearing edge loading or Non-uniform loading

Smooth and best turning gear operation , especially when T.G. , where jacking oil is required to lift rotor

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Shaft alignment

External Measurements

May 2009

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Fix Points

Ensure that ;

All Fix points are reamed and tightly inserted

May 2009

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Bumping Test

Radial clearance

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Turboset arrangement

Front end bearing

Exhaust end bearing

DE bearing NDE bearing

NDE bea

Front end base plate

Front end base plate

Exhaust casing support Rigid coupling

Absolute

expansion

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External

shaft

alignment

turbine

-

generator

GeneratorTurbine

Static

deflection

line

Kinetic

deflection

line Outboard bearing

to be

raised

by

3,6 mm

0,3 mm

Front and exhaust

end turbine

bearings

horizontalTurbine and Generator

flange parallel

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Max. permissible

external

forces

and moments

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External forces

Ensure stress free connections

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Sample ;

-

shoulder bolts

(horizontal/vertical)

- improvement of sliding

behavior of importance,

if not already existing, than

to be modified accordingly

Ensure Free Expansion

May 2009

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Recommendation

Modified front end bearing housing

May 2009

24


Sliding Plates required improvement

Sole plate with wear after 50.000 operation hours

Selflubricating

sliding plate beneath front bearing pedestal

The intention must be to keep the displacement forces exerted by the front end bearing pedestal on the sole plates and thus the coefficient of friction as small as possible. Only then uniform expansion and contraction of the bearing pedestal is possible, especially without any abrupt movements.

Old design

New design

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Benefits

Small coefficients of friction during expansion and contraction of the turbine casings and thus reduction of load on the axial connecting and fixing elements and on the casing, bearing pedestal and foundation

Continues sliding of the bearing pedestal during start up and shutdown without any abrupt movement in terms of absolute and relative expansion

Prevention of tilting and or skewing of the bearing pedestal as a result of high friction related sliding forces and thus impermissible bearing loadings ( edge supports )

Ease of replacement of the sliding plates

Alignment / Inclination correction of pedestal , can also be done during minor overhaul, since height adjustment from outside

May 2009

26


Thanksfor your attention

27Cairo, May 2009

Siemens AG, Power Generation

Industrial Application

Documents

08. Detlef - Alignment&Dummy Cairo