DLN Retrofit in Two Frame 7 Gas Turbines RasGas LNG Company-Qatar

7/29/2019 DLN Retrofit in Two Frame 7 Gas Turbines RasGas LNG Company-Qatar

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DLN Retrofit in Two Frame 7 Gas TurbinesRasGas LNG Company-Qatar

Presenters:Amr Gad

Atul Deshpande

RasGas, Qatar

Turbo 41 - Houston Texas

Date: 27 September, 2012


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Contents

Summary of the project

DLN1 Fuel Staging & Operational Modes

Process Compressors for RasGas Train 3

Requirements for DLN retrofit for Gas Turbines

Project Milestones

Project Organization

Project Details & Results

Challenges & Lessons Learned


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Summary of the project

Regulations set by Ministry of Environment to achieve NOx emissions

of 25 ppm for such turbines.

Two retrofitted units are driving Mixed refrigerant and propane in the LNG

refrigeration cycle.

Project engineered in years 2009-2010 and implementation done in year

2011 successfully.

1st successful DLN retrofit for Frame 7EA Gas Turbines in an LNG train.


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DLN1 Fuel Staging & Operational Modes

Transfer Mode

Diffusion Flame100% Secondary Fuel

50% Load

Premixed ModePremixed Flame / Diffusion Pilot

81% Primary / 19% Secondary Fuel

50% - 100% Load For IBH machines

or 80%-100% Load for machines wi thout IBH

F/A

Mixing

Lean-Lean ModeDiffusion Flame

~60% Primary / 40% Secondary Fuel

19% - 50% Load

Primary Mode

Diffusion Flame100% Primary Fuel

Ignition - 19% Load

Diffusion

Diffusion

Diffusion/Premix

Diff /Premix

Premix

Primary Zone Dual Purpose: 1. Low Load Diffusion Flame 2. High Load Premixing Chamber


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Process Compressors for RasGas Train 3

Propane

Compressor

Mixed Refrigerant

Compressors

Main Cryogenic

Heat Exchanger

LNG to Storage

C5+ NGL

Scrub

Column

Feed

Gas

Propane Precooled MCR Process

3,600 rpm

PROPANECOMPRESSOR

FRAME 7MOTOR

3,600

rpm

LP MRCOMPRESSOR MP MRCOMPRESSORFRAME 7 MOTOR

HP MRCOMPRESSOR

Frame 7 Gas Turbine


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Requirements for DLN retrofit

Stable fuel gas supply pressure

Rate of change of MWI

Contaminant free fuel gas

Turbine Control logic upgrades for mechanical drive application


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Adequate & stable fuel gas supply pressure

Increase the fuel gas supply network pressure

Fuel Gas Pressure Control Ramp Up Logic :

Considers scenarios of fuel compressor trip or upset

Ensures fast make-up from back-up sources of fuel gas i.e. Fuel From Feed (FFF ) or Boil

Off Gas (BOG) to sustain the minimum fuel gas supply pressure

Fuel Gas Pressure


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Train-3 Fuel Gas Supply System

26.50

83000 C

D

31.5 28.2

52000

33-FV307A

93-PV3002

Drier Regen.

/ Selexol

93-V061 Fuel Gas

Mixing Vessel

93-PV3003A

93-PV3003C/D

93-PV3003B

93-E063

Wet Gas Flare

36-KT001/004

93-E052

PC

3003

38-E005

PC

300238-K001

93-V062

Train 3 FG Pressure Control Overview

FT

0830

FT

0821FC

307A

barg

barg

Nm3/h

barg

Nm3/h

Current pressure at Turbine FG

skid Inlet = 25.9 barg

Addi tional

compressor

capacity marginal,

amps approaching

100% of rated load.

PSV's set at 34.5 barg

How to achieve 27.8 barg at PC3003 and 26.3 barg at inlet to turbine

fuel gas skid?

1

2,3 4

5

6

16

Fuel Gas Compressor

Frame 7 Gas Turbines

Fuel From Feed KO Drum


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Limited changes in the fuel gas Modified Wobbe Index ( MWI ):

Resized the Fuel gas mix drum to meet max. MWI rate of change of

0.3%/sec from existing of 0.5%/sec.

The new fuel gas mixing drum is around 25% bigger in volume to

meet the rate of change of MWI as above

Fuel Gas Quality


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Meets OEM spec for fuel gas in terms of maximum allowable contaminants.

LL from existing train indicates presence of Selexol can act as an ignition source

& cause fire in fuel gas piping at valve skid in event of passing purge valves.

Additional requirements resulted in upgrades in the fuel gas system as follows:

Upgraded fuel gas filter skid to meet specs for liquid carry over & particulate

size.

Upgraded demisters for upstream fuel gas treatment column & KO drum.

Provision of demister in the fuel gas mixing drum.

Low point drains.

Modified fuel gas skid with piping layout to prevent Selexol accumulation.

Fuel Gas Contaminants


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Lessons learned from another train:

Selexol carry over for fuel system

Auto ignition of accumulated Selexol in presence

of hot air from axial compressor discharge

No combustion dynamics monitoring


Contaminants Free Fuel Gas


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New Fuel Gas Valve Skid


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Train-3 Fuel Gas treatment unit

44554

148.376.4 SPT 120.0

PV 120.5

27.6 OUT 18.0%

SPT 29.0 40.1 39.6

PV 27.7 39.3

OUT 0.0% 5.4

39.2

7.4

38.9

27.2

38.8 SPT 40.0

27.7 PV 40.1

OUT 23.2%

45300 34.3 PV 36.9

38.0

33-C010

33-V010

LC

0201

FC

0201

PC

0201

barg

barg

barg

mbar

mbar

mbar

mbar

barg

oC

oCNm

3/h

Nm3/h

m3/h

ppm

ppm

13

14

15

Demisters upgrade for

Selexol Absorber 33-C010 &Fuel gas KO drum 33-V010

Demister upgrades


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Filter elements are suitable for maximumoperating temperatures 82C. Cartridges elements, made ofCS604LGBH1 which is a amine compatible

element working as coalescer element.

Condensate/ heavy Hydrocarbons

Continuous flow phaseDispersed phase

One

coalescer

cartridge isshown

N I

N II

N III

N IV

New Fuel Gas Filter Skid

New demister tray inside mix drum


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Milestones

Gate-1/ 2:

Scope, strategy development, feasibility-technical & economic

Pre-Feed & management approval: Aug09.

Gate-3:

What if Analysis: Aug 10.

CDRA: Sep10.

HAZOP: Oct10

Cold Eye Review : Nov10.

Gate-4:

Constructability Readiness Review : Feb11

Detailed Engineering completion & construction readiness: March11

Gate-5: Construction, commissioning & start-up:June11

Gate-6: Close out: & LL: Oct11


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Project Organization

RG Project Manger

Technical Lead Project EngineerConstruction LeadQA/QC Lead

GE Project Team EPCM Project Team

RG Project steering committee


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Project Details & Results

Engineering man hours : 30,000 approx.

Construction Man hours: 90,000 approx.

Excellent safety records during construction.

Construction and commissioning meet the plan schedules.

Both turbines successfully re-commissioned post DLN retrofit

Achieved NOx emission reduction:

Frame 7EA emissions

0.050.0

100.0150.0

200.0250.0

NOx

mg/Nm3

SO2

mg/Nm3

O2

%

Emissions

Valu

e

3rd Q 20073rd Q 2011


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Challenges & Lessons Learnt

Limited train shutdown duration of 22 days (Mechanical)

Incorporate lessons learned from other frame 7EA DLN machines result in

increase LNG train reliability:

Fuel gas contaminant control measures (Filters, demisters, etc)

Ramp-up logic for stable fuel gas supply pressure

Additional scope for reliability improvement : Combustion Dynamic monitoringsystem

Job Clash: Simultaneous construction with other activities during shutdown

(Compressor overhaul, turbine major inspection and heavy lifting activities)

Interface management with multiple parties

Technical & project management issues

Brown field application : Requirements of Smooth startup without production

impact.


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[ ] RasGas Company Limited 2012

Thank you

DLN Retrofit in Two Frame 7 Gas Turbines RasGas LNG Company-Qatar

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