Liners Faliure

8/11/2019 Liners Faliure

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Fr7AE Gas TurbinesDry Low-NOx Combustion System

Operating Challenges in O&G Plants

Atul W. Deshpande RasGasLuis A. Rojas RasGas

V. Venkatachallam RasGasMustapha Chelghoum RasGas


2/17

Executive Summary:

After a planned Shutdown and transfer valvereplacement, Propane unit -GT Fr7AE DLN1-started;

Unit failed to transfer to pre-mix steady stateMode (PMSS) and Trip.

05 Days of online troubleshooting using FishboneDiagram, to determine why the unit couldn

tsustain on PMSS mode after several transfers.

Visual inspection of the internal Combustionsystem reveal hardware damages.

RCFA-PROACT Methodology used to investigateand find the causes of the damages.


3/17

Why DLN1 system on Gas Turbine andHow it works during Startup?

The DLN-1 for FR7AE GT meet Qatar Ministry of environment (MOE)in terms of emission norms (NOx < 25 ppm).

Axial AirCompressor

Airinlet

PowerTurbine

Purge AirFlangeConnection toPurge Valves

Vent

PurgeValve-1

PurgeValve-2

VGC-3

FUELGAS

SRV

VGC-2

VGC-1

PrimaryFuelManifold

Transfer/ PurgeManifold

Secondar y FuelManifold


4/17

Fishbone Diagram for Online Troubleshooting


5/17

Combustion Inspection Findings

Carbone DepositsOn Primary andSecondary Nozzles

ThermalDamage


6/17

Combustion Inspection Findings:Combustion Liner No 5: Major damage

Liner #5 CrackedCircumferentially

Material MeltedDown Insidethe Liners.

Liners LateralCracks

Liner CapsDeformation

Loss of Material


7/17

Combustion Inspection Findings:Combustion Liner No 4: Major damage

Liner #4 CrackedCircumferentially

Missing PieceNear Hula Seal Cracks and

LateralMovement

3 Liner CapsDeformedDownward


8/17

Root Cause Failure Analysis RCFAEvent Diagram:


9/17

Investigations..1Control System Trends.

Fuel gas Pressure Fluctuations before the event


10/17

10

Investigations ..2Control System Event Trends during transfer

Spike in Compressor Pressure &Exhaust temperature


11/17

11

Investigations..3Purge Air Connection on Wrapper

Side View of Wrapper

Purge AirConnectionTo Wrapper

2

4

3

5

EndView

Gas

Air

Liner DamageArea

Purge Air Connection on Wrapper Close to combustion can #4&5


12/17

12

Investigations..4Purge Valve installation

Same SAP number Normally closeactuator & Normally Open actuator

Ball closes opposite toseat leaving wide gap

in closed condition

Closing opposite to seat/Incorrect SAP material number


13/17

Investigations..5Fuel Gas System.

13

Selexol draineddaily

53 - C010

SELEXOL Absorber

LC

53 - V010

SELEXOL KO DRUM

Unit 53 Battery Limit

93 - V121

FG MIXING DRUM

EFG FFF

93 - E122

~50 C

~42 C

FG scrubber& strainer skid

56 - Y004

FG Valve Skid(56 - Y002)

Gas Turbine (56 - KT004)

FG scrubber& strainer skid

56 - Y003



LeanSELEXOL

solvent

Rich

LC LC

53 - V010

SELEXOL KO DRUM

Unit 53 Battery Limit

93 - V121

FG MIXING DRUM

EFG FFF

93 - E122

~50 C

~42 C

FG Filters 56 - Y004



FG Filters

56 - Y003



LeanSELEXOL

solvent

RichSELEXOL

solvent

Regen gas fromdehydration unit

(Unit 53)

FFF (duringstartup)

~65 C

~48 kNm3/hr

Excess gas to fuelgas header

~15 kNm3/hr

~15 kNm3/hr

Sour Gas Flare

Fuel gas strainer

Filters Specification 0.3m for solid &

liquid removal, existing 3m for solidonly .

Mixing drum not a knock outdrum (no demister) Upstream demisters noteffective


14/17

RCFALogic Tree (1)

14

Hardware damagedue to uncontrolled

combustion


15/17

RCFALogic Tree (suite)

15

Main Cause:Backflow of Fuel gas

through purge lineContributing Fact:

Liquid accumulation due toinadequate Filtration and

piping lay out


through purge line


through purge lineContributing Fact:

Liquid accumulation due toinadequate Filtration and

piping lay out

Contributing Fact:Liquid accumulation due to

inadequate Filtration andpiping lay out


16/17

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RCFARecommendations

Work Management:

Change SAP material code for the purge valve actuator. Develop Purge Valve Installation Procedure. Time based purge valve replacement.

Engineering Design:

Upgrade purge valves, actuators, solenoid. DLN mode transfer software modification. Upgrade fuel gas filtration system & DLN valve skid layout. Upgrade demisters of Selexol Absorber & mixing drum. Install Combustion Dynamics Monitoring system for allFrame 7 DLN Gas turbines.

All recommendations have been implemented.


17/17

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Questions?

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