DLN Retrofit in Two Frame 7 Gas Turbines RasGas LNG Company-Qatar
Transcript of 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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Requirements for DLN retrofit
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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Requirements for DLN retrofit
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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Requirements for DLN retrofit
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
Requirements for DLN retrofit
Contaminants Free Fuel Gas
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Requirements for DLN retrofit
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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Requirements for DLN retrofit
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