Compressor Variable Inlet Guide Vane System

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GT13E2Operation

Compressor VariableInlet Guide Vane System

Training Lesson

ALSTOM (Switzerland) Ltd ABCD


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GT13E2 Compressor VariableOperation Inlet Guide Vane System

Power Plant Training Center

CSXA220259enA Page 2

ABCD

We reserve all rights in this document and in the information contained therein.Reproduction, use or disclosure to third parties without express authority is strictlyforbidden.Copyrightby ALSTOM (Switzerland) Ltd 2007

This is a training lesson. It provides overall information about the specific system

only.To understand the operation concept in detail the project specific documents asdefined in the document reference section have to be included together with thislesson.

All mentioned / attached values and settings are for information only. Typicalvalues are used to clarify particular subjects. Settings furthermore are subject tochange site specifically during commissioning.For actual values please refer to the final plant specificOperation & Maintenance Documentation.


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Table of Contents

Document Reference ........................................................................................................................... 4Typical Documents........................................................................................................................... 4

O&M Documentation....................................................................................................................... 4Lesson Objectives................................................................................................................................ 5Overview............................................................................................................................................ 6

System View on Operation Station..................................................................................................... 6System Function ............................................................................................................................... 7

Function Description............................................................................................................................ 8Operation and Supervision................................................................................................................ 10

General......................................................................................................................................... 10Start-up of the Gas Turboset........................................................................................................... 10Normal Operation (Load Operation)............................................................................................... 11

Shutdown ...................................................................................................................................... 12

Rotor Barring ................................................................................................................................. 12Compressor Off-line Washing ........................................................................................................ 13Standstill of Gas Turboset ............................................................................................................... 13

Monitoring Equipment ....................................................................................................................... 13Protection and Fault Causes............................................................................................................... 14

General......................................................................................................................................... 14Malfunction and possible Causes .................................................................................................... 14

Exercises........................................................................................................................................... 15General......................................................................................................................................... 15Overview....................................................................................................................................... 15

Component Name, KKS Designation & Function.............................................................................. 16Operation ..................................................................................................................................... 17

Test Questions for Verification of Learning Progress ......................................................................... 18Questions:..................................................................................................................................... 18Lesson Test Questions Solution Key ................................................................................................. 20

Summary.......................................................................................................................................... 20Adjustment of the Compressor VIGV System ....................................................................................... 21

Simplified Diagram........................................................................................................................ 21Designation of Parts ....................................................................................................................... 22

Table of Figures

Figure 1: Operating Station Image including Variable Inlet Guide Vane System (Typical)........................ 6Figure 2: Adjusting Drive and VIGV Instrumentation (Typical)................................................................ 7Figure 3: Variable Inlet Guide Vane (Typical) ....................................................................................... 8Figure 4: Definition of the Angle Position (Typical)................................................................................ 9Figure 5: VIGV Schedule during Startup (Typical) ............................................................................... 10Figure 6: VIGV Schedule during Load Operation (Typical) .................................................................. 11Figure 7: VIGV Schedule during Shut Down (Typical).......................................................................... 12

Figure 8: Angle Transmitter (Typical) ................................................................................................. 13


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Document ReferenceTypical Documents

Typical documents are used to clarify aspects described in this lesson. These typicaldocuments may not show project specific contents, deviations are possible. Alltypical documents are clearly identified.

O&M Documentation

O&M Documents are plant specific and form an important part of each trainingcourse. A selection of the most relevant O&M Documents has been made andincluded in the training course material. These documents provide a basis forexercises and personal notes, markings, etc. The most relevant documents for theoperation training are:

P&IDs with legend

GT operating concept

System description

Maintenance manual

The O&M Documents are separated into:

System specific documents

Overall plant specific documents

The system specific documents are in principle notattached to each specific lesson,whereas the overall plant specific documents can be found in separate sections atthe end of the training manual.


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Lesson Objectives

Upon completion of this lesson, the trainee is able to:

State the functions performed by the compressor variable inlet guide vane(VIGV) system.

Describe the components of the VIGV system.

List the parameters which are monitored.

Describe the protection actions initiated by measurements MBA82 CG001/002.

State the angle position of the VIGVs during: Standstill of the gas turbine, TAT < 60 C, Startup, Operation, Shutdown, Rotor barring.

Give the probable causes for the alarm: Incorrect angle of the VIGVs.


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OverviewSystem View on Operation Station

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Figure 1: Operating Station Image including Variable Inlet Guide Vane System (Typical)


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System Function

Purpose The purpose of the compressors Variable Inlet Guide Vane (VIGV) system is to: Expedite the gas turboset startup, thus ensuring rapid availability of electric

power.

Reduce NOXemissions by optimizing the fuel-to-air ratio at partial power loads.

Adjust the air flow to the compressor according to the requirements of thethermodynamic cycle.

Enable load control between approximately 60 % load and base load.

Components The major components of the compressor VIGV system are:

Inlet guide vane row (52 vanes) with adjusting ring. Linear amplifier (hydraulic cylinder) .

Pilot proportional valve for linear amplifier.

Safety and monitoring equipment.

CSXA402946.cdr

Figure 2: Adjusting Drive and VIGV Instrumentation (Typical)


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Function Description

The angular position of the VIGV row adjusts the air flow through-the axialcompressor, modulating it between start-up and base load conditions.The row, sometimes called the zero compressor stage, is connected to anadjustment ring via a tie rod. The adjustment ring, which runs around thecircumference of the compressor housing at the air inlet section, is mounted so thatit can turn. It is driven by a linear amplifier, which is connected to the power oilsystem.

A pilot proportional valve regulates the position of the linear amplifier, which isindirectly monitored by the position (angle) measurement. The proportional valveallows the VIGV row to assume any position between open and closed.The angular position of the VIGV row, and the position of the piston inside the

proportional valve are monitored by electric current position converters.The position of the proportional valve is automatically set in a closed loop by anelectrical signal via an amplifier card from EGATROL.

CSXA402961.cdr

Angle transmitter

Tie rod

Adjustmentring

Figure 3: Variable Inlet Guide Vane (Typical)

(Continued next page)


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Function Description (continued)

CSXA402948.cdr

(duringstart-upandlow

load

V

ariableinletguidevanes-30

o

peration)

Variableinletguidevanes-65

(fullyclosedposition)

Variableinletgu

idevanes0

(fullyopenpositionduring

baseloadoperation)

Airflo

w

-65

Airflow

-30

Airflow

Position0

Angle

Figure 4: Definition of the Angle Position (Typical)


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Operation and SupervisionGeneral

The system must be operated in accordance to the Operation Manual and theOperation Concept which should be read carefully.

Start-up of the Gas Turboset

Before starting acceleration of the rotor the VIGV start opening by a programmedcharacteristic from closed position (angle -65) to open position (angle -0). This iscompleted when rotational speed has reached approx. 70 rpm. The VIGVs remainin this position during the purge cycle of the gas turbine and - if available the heatrecovery steam generator.After purging, when reaching the sequencer step ignition the VIGV position ischanged to start up position (-30) and remains unchanged during furtheracceleration, synchronization and as long as the gas turboset is in lower loadrange.

CSXA402962.cdr

VIGV position: closed / -65 / 16.6%

VIGV position: open / 0 / 88.8 %

Nominal speed : 3000 rpm / 90%

VIGV position: start -30 / 55.5%

GT13E2 VIGV during start up

Time

Purge Speed 835 rpm / 27.6% Ignition speed:

Fuel oil 32 % of nominal speed / 950 rpm

Fuel gas 20% of nominal speed / 600 rpm

0

20

40

60

80

100

0

20

40

60

80

100

Spee

drp

m

[0

to3333/

0to100%

]

VIGV%

[-8

0to+

10/

0to100%

]

Figure 5: VIGV Schedule during Startup (Typical)


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Normal Operation (Load Operation)

Load control in the part-load range between minimum load to about 65 % ofrelative load is done by increasing the turbine temperature, the VIGV aremaintained in idle position. Between about 65 % of relative load to base load theair massflow through the gas turboset is increased by opening the VIGV to fullyopen position.

CSXA402968.cdr

max.TAT max.TIT

Idle

100

0

200

300

400

500

600

700

800

900

1000

1100

1200

0 10 20 30 40 50

Power[% baseload]

60 70 80 90 100

Baseload

-30

-25

-20

-15

-10

-5

0

VIGVang

le[Deg]

TIT[C],

ex

haust

massflow

[kg/s]

TIT

TAT

Exhaust mass flow

VIGV angle

Figure 6: VIGV Schedule during Load Operation (Typical)


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Shutdown

During normal unloading, the operating sequence of the variable guide vanes is inthe reverse order to that during the loading cycle. At about 65 % of relative load the

VGVs are in the start position again. They remain in this position during furtherdeloading, idle cooling time and shut-down until 35 rpm. Below that rotor speedthe VIGVs change to fully closed position.

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GT13E2 VIGV shut down

Spee

drpm

[0

to3333rpm

/0

to100%

]

VIGV%

[-8

0to+

10/

0to100%

]

Time

VIGV position: -30

Rotor speed 35 rpm

Rotor speed 33 rpm

VIGV position: -65

0

10

20

30

40

50

60

70

80

90

100

-80

-70

-60

-50

-40

-30

-20

-10

0

10

Figure 7: VIGV Schedule during Shut Down (Typical)

Rotor Barring

During rotor barring operation the VIGV remains in fully closed position.


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Compressor Off-line Washing

During the spraying cycle the VIGV are fully open, during drying the VIGV close toidle position.

Standstill of Gas Turboset

The variable guide vane row is in the fully closed position when the gas turboset is

at a standstill.

Monitoring Equipment

AngleMeasurement

The angle of the variable inlet guide vanes is measured by two angle transmittersand displayed on the Operator Station. The two angle transmitters are mounted

directly to the shaft ends of two variable guide vanes.An alarm is activated whenever the angle of the VIGV deviates from the requiredposition.Protective load shedding of the gas turboset is initiated if the angle continues todecrease below the preset limit or the difference between the required angle andfeedback (actual angle) exceeds the preset limit.

Figure 8: Angle Transmitter (Typical)



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Monitoring Equipment (continued)

Position

Measurement

The spool position of the pilot proportional valves is monitored. This actual position

is transmitted to the amplifier card where the value is compared with the set valuegiven from EGATROL.

Protection and Fault CausesGeneral

The protection functions of the control system provide the greatest possible safeoperation at the highest possible efficiency and availability. They operate on threethreshold levels:

Alarm annunciation

Protective load shedding

Trip of gas turboset

All protection interventions must be promptly investigated, the source found andrectified so that unit can be returned to normal operation as fast as possible.

Annunciation in the case of protection interventions appear on the OS, includingname, KKS code, values and other relevant information to indicate the source of

malfunction.

Malfunction and possible Causes

Incorrect angle of the VIGV

Possible

Causes:

Linear amplifier or electronic controller defective.

Angle transmitter is defective.RequiredAction:

Investigate until the source of the problem is found, take allactions necessary to bring the gas turboset to normal operation.


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ExercisesGeneral

To be able to understand the exercises the relevant chapter of the following projectspecific documents must be studied carefully:

P&ID including legend

Operation concept of the gas turbine

Overview

System &Components

This section contains the following exercises:

Component name, KKS designation & function

Operation concept of the gas turbine


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Component Name, KKS Designation & Function

Exercise Task Fill-in the table below with the following information according to the examplegiven in the first line:

Major components name

KKS number

Short functional description

Exercise Aids Plant specific P&ID and legend

Group

Time Frame

Each trainee for himself

5 minutes

Component Name KKS - Number Component Function

Power oil system MBX 40 Provides pressurized oil


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Operation

Exercise Task Describe the VIGV schedule during Startup, Load Operation and Shut down.

Exercise Aids Plant specific P&ID and legend

Plant Operation Concept

Group

Time Frame

Presentation

Group work with max. 4 trainees per group

10 minutes

Group presentation in front of class

Description

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................

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Test Questions for Verification of Learning Progress

General The following points are important and shall be taken into account: The training manual may be used (open book), but first try without looking up in

the manual.

Mark the box in front of each correct statement with a diagonal cross.

One or more or all statements may be correct.

Use this section to verify your learning progress! Review subjects, which are notclearly understood.

Questions:

Question 01: Purpose of the variable inlet guide vanes is:

A Reduction of rotor vibrations by optimizing the air flow into the axialcompressor

B Load control in the higher load range of the gas turboset

C Reduction of contamination of the axial compressor

D Expedition of the start up of the gas turboset

E Diverting of a portion of air from the axial compressor which is requiredfor cooling purposes

F Optimization of the fuel-to-air ratio in order to reduce NOXemissions



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Questions (continued):

Question 02: The opening position of the VIGVs are:

A Proportional to the load between minimum to base load

B Proportional to the rotational speed of the gas turboset

C Fully open when cleaning agent or water is injected into the compressorwhen compressor washing

D Is controlled by EGATROL dependent on load output, turbine inlettemperature and temperature after turbine

E Not influenced by ambient conditions

Question 03: The VIGVs are in closed position:

A During all the time when compressor washing

B As long as TITmax has not attained

C As soon as a gas turbine trip is initiated (to prevent a thermal shock ofthe hot path parts

D During rotor barring operation

E When purging the exhaust diffuser and heat recovery steam generator

F As long as the blow off valves are open

Question 04: The actuation range of the VIGVs is defined by:

A 0 to +65

B 0 to -30

C -65 to 0

D 0 % to - 65 %


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Lesson Test Questions Solution Key

The correct answers for each question are as follows:01: B, C, F

02: C, D, E

03: D

04: C

Summary

ObjectivesReview

Carefully review the objectives stated on page 5 of this lesson together with the TestQuestions for Verification of Learning Progress.Note that this lesson is not complete without the system specific and overall plantOperation & Maintenance Documentation.

Summary The purpose of the Variable Inlet Guide Vanes I(VIGVs) is mainly to control the loadoutput of the gas turboset. Below of about 60 % of base load the VIGVs are set at

-30. When increasing the load the VIGVs are opened thus increasing the massflowof air through the gas turbine. At base load the VIGVs are in fully open position.The VIGVs further reduce the NOXemissions by optimizing the fuel-to-air ratio atpartial load.The training lesson describes the main components, how the system functions andits different operation modes.


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Adjustment of the Compressor VIGV SystemSimplified Diagram

CSXA402965.cdr

LOAD OPERATIONSTART-UPCLOSED

MBA80

MBX52A 002A

MBA82A 001S

MBX71

MBX40

GCMBX52 CG001

GIC(Z)A-MBA82 CG002

GIC(Z)A-

MBA82 C 001G

P A

BT


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Designation of Parts

KKS-No. Designation

MBA80 CompressorMBA82 Adjustment mechanism for variable inlet guide vaneMBA82 AS001 Linear amplifierMBA82 CG001 Measurement of guide vane positionMBA82 CG002 Measurement of guide vane positionMBX40 Power oil systemMBX52 Power oil system for variable guide vane adjustmentMBX52 AA002 Control valve for variable guide vane adjustmentMBX52 CG001 Control valve positionMBX71 Power oil return