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Fuel oil SystemGT 5-8
Muhammad Arshad MukhtarTrainee Engineer
Contents
Introduction Forwarding Skid Filtration Skid Fuel Oil ON-base System Protections
Tank Area
Total No of tanks 27
Treated tank 11
Untreated tanks 11
HSD Tanks 5
Forwarding Skid
Purpose of forwarding Skid
To remove solid particles from the oil. To increase the pressure of HSD & BFO Heating of BFO
GT 5-8 HSD Forwarding Skid
63FD1X1
63LF-1D 63FD-2
GT 5-8 BFO Forwarding Skid
BFO Tank
20 FH-1
63LF-1U
63FU1X1
63 FU-2
Filtration Skid
Purpose of filtration Skid Filtration Fuel consumption measurement Machine Fuel Changeover HSD heating
FO Circulation
20 FH-2
20 FD-1
26FU-263LF-2D
63LF-2U
26FD-2
Fuel Change Over Conditions(HSD to BFO)1. BFO Temperature < 115 C2. BFO Temperature >90 C3. BFO Pressure > 4.6 bar4. HSD Temperature > 46 C5. L63 6. Dosing System Should available7. 20 FT & 20 FE Should De-energize
Cont….
8. Generator Circuit Breaker Should Close9. BFO suction Pressure 10. BFO Discharge Pressure
Fuel Oil On Base System
Purpose Pumping of fuel Distribution of fuel Filtration
OD
OD96 FP – 1,2
65 FP
P R
1 2
FH 3
OH 3
SEE HYDR SUPPLY
OF - 2
OF - 5
20 FE
Dosing
20 FTVPR15
AD-1
FO
HSD
Air supply
Fuel change-over valveMBN10 AA016
63FL-2
VR27
To sump tank
PF 1
LF 6LO 7
Accessory gear box
OL
NO
DF - 2Fuel Gas
Atomizing air Inlet
Purge Drain to Sump
Tank
Purge air
Hydraulic
oil supplyTrip oil
VH 4
VS 120 CF
VR 4
VC 3
Main Fuel Oil Pump
FD 1
77 FD 1,2,3 Selection valve
assembly
Liquid Fuel System –On Base
Sump bolted to Base
HP Filters
Gauge Cabinet
Filtration Skid Fuel Oil Transfer Valve
VC
K-1
VC
K-2
20 FL-1
20 CF
Solenoid Valve 20 FD-1Solenoid Relay Function Energize De-
Energize
20 FD-1 L20FDXEnergize to supply air for opening of HSD Stop valve
Feed pipe purge is running and sump tank level is not highL20FTX=0 and L4FDZ = 1Fuel change over valve is not towards FO (L33TUC = 0) and L4FDZ=1
Feed pipe purge is running and sump tank level goes highIf HSD pump stops L4FDZ = 0Fuel change over valve is towards FO (L33TUC = 1) and L4FDZ=1 if L20FTX=1 and L4FDZ=1
Solenoid Valve 20 FH-1Solenoid Relay Function Energize De-
Energize
20 FH-1 L20FH1x
Energize to supply control air to FO temperature control valve EGC 53 AA117 at forwarding skid and also supply air to divert the FO return from filtration skid to inlet of pump rather to FO inlet upstream
FO pump is in ServiceFO temperature < 115 CFO pressure at forwarding > 6 bar
FO pump stopsTemperature> 115 CPressure < 6 bar
Solenoid Valve 20 FH-2Solenoid Relay Function Energize De-
Energize
20 FH-2 L20FH2x
Energize to supply control air to HSD temperature control valve which regulates HSD temperature at 46 C while changeover from HSD to FO
FO temperature > 90 C(L26FU2L z=0)Heavy transfer signal given(L83FU=1)NO lock out for FO(L86FT=0)
Solenoid Valve 20 FESolenoid Relay Function Energize De-
Energize
20 FE L20FE1X
Energize in series with 20FT to supply air to fuel changeover valve MBN10AA016 to change its position from HSD to FO.
20FT is energized and L4=1 and L84TL=1 FO pressure is >4.5 bar at filtration skid or >6bar at forwarding skid
L4=0 or L84TL=0 FO pressure is <4.5 bar at filtration and <6 bar at forwarding skids
Solenoid Valve 20 FT
Solenoid Relay Function Energize De-Energize
20 FT L20FTX1
Energize in series with 20 FE to supply air to fuel change over valve MBN 10 AA016 to change its position from HSD to FO
Heavy fuel transfer per missives are O.K (L3FU=0)Generator breaker is closed (L52GX1=1)heavy fuel transfer signal is given (L83FU=1)there is no lockout for heavy fuel transfer (L86FT=0
Generator breaker is opened (L52GX1=0)transfer signal is removed (L83FU=0)heavy fuel transfer is locked out (L86FT=1
Solenoid Valve 20 FL 1
Solenoid Relay Function Energize De-Energize
20 FL 1 L20FLX1
Energize to close the drain port of trip oil and supplies trip oil pressure for opening of hydraulic trip valve VH-4 which lets pass hydraulic oil to open liquid fuel stop valve VS-1.
5 seconds after pump satred L4FDZ=1 and turbine vent timer is completeHeavy purge is selected and L4FDZ=1Flame is detected on at least 2 detectors (L28FDX=1).
L4 = 0
HSD pump stops
Solenoid Valve 20 CFSolenoid Relay Function Energize De-
Energize
20 CF L20 CF1X
Energize to engage magnetic coupling of main fuel oil pump
Liquif fuel stop valve solenoid is energized (L20FLX=1) and Liquid fuel stop valve open limitswitch is operated (L33FL2O=1) and L63FL1X=0 (pressure not less than 4.5 bar for 5 seconds) and L63FL2L=0 (Liquif fuel pressure is > 4.5 bar).
L20FLX=0 or L63FL1X=1
Fuel Pressure Discharge Relief Valve VR-4 It prevents from getting high enough to
rupture any line in the event of a flow divider malfunction or freeze up.
Operating Range 81 to 88 bar
Flow Divider FD-1
Continuous flow, free wheeling
14 gear pump elements
3 magnetic pick ups
Magnetic Pick ups (77 FD-1,2,3)
It monitors the flow divider speed.
It produce a flow feed back signal at a frequency proportional to fuel flow delivered to the combustion chamber.
False Start Drain Valve
These valves are used for drainage of incombustible fuel during unsuccessful start.
Valve Closing through Compressor Discharge air
Valve opening through Spring Force
ProtectionsIndication Sensor & settings
ResultCause Action Required
Dist fuel filter Diff Press High (Upstream)
High differential pressure (0.2 bar↑) of in-service HSD filter at forwarding skid sensed by ΔP switch 63LF-1D.
Alarm Choking of filter or wrong operation of 63LF-1D. Normal value is 3.5bar
Check local differential pressure. If filter is dirty, take stand-by filter is service and get dirty filter cleaned. If local pressure is normal, check discharge pressure of HSD forwarding pump and call I&C section to check the pressure switch.
Dist. Pumps’ upstream pressure low
Suction pressure of HSD pumps hasdropped to -0.5 bar↓ sensed by pressure switch 63FD1X1.
Alarm Tripping of HSD booster pumps. Choking of filters. Wrong operation of 63FD1X1. Fuel tank level is low.
Check local pressure at suction of HSD forwarding pumps. Inform fuel supervisor to check level of HSD tank and operation of booster pump. If pressure is normal then call I&C section.
Distillate skid trouble
Low discharge pressure (6 bar↓) of HSD forwarding pump sensed by pressure switch 63FD-2.
Alarm Low pressure at pump suction. Choking of suction filter. Failure of supply. Fault in pump. Leakage from system. Wrong operation of pressure switch.
Check discharge pressure of pump and take stand-by pump in service if pressure is low. Call I&C people to check the pressure switch if discharge pressure is normal.
Cont….Indication Sensor &
settings ResultCause Action Required
Heavy fuel filter Diff Press High (Upstream)
High differential pressure (0.2 bar↑) of in-service FO filter at forwarding skid sensed by ΔP switch 63LF-1U.
Alarm
Choking of filter or wrong operation of 63LF-1U.
Check local differential pressure. If filter is dirty, take stand-by filter is service and get dirty filter cleaned. If local pressure is normal, check discharge pressure of FO forwarding pump and call I&C section to check the pressure switch.
Heavy pumps upstream press Low- Transfer to dist.
Low pressure (-0.5 bar↓) at suction of FO forwarding pumps sensed by pressure switch 63FU1X1.
Alarm + Auto changeover from FO to HSD.
Tripping of FO booster pump. Choking of filters. Wrong operation of 63FU1X1. Normal value is 3.5bar
Check local pressure at suction of FO forwarding pumps. If pressure is normal then call I&C section.
Heavy skid trouble
FO discharge pressure at forwarding skid dropped to 6.0 bar sensed by pressure switch 63FU-2 (EGC50CP012).
ALARM + Stand-by pump will cut in on auto
Low discharge pressure of FO forwarding pump.
Check discharge pressure of running pump. Call mechanical people to find out reason for low pressure.
Cont….Indication Sensor & settings
Result
Cause Action Required
Heavy fuel temp. Low, Auto transfer to Dist.
FO temperature is 90±2°C at inlet of FO/HSD heat exchanger sensed by temperature switch 26FU-2 (MBN70CT001).
Alarm + Auto transfer from FO to HSD
Low temperature of thermal oil due to tripping of thermal oil heater. Fault on FO temperature control valve # EGC53DT001. Tripping of air supply solenoid valve 20FH-1.
Check thermal oil temperature. Check proper functioning of thermal oil regulating valve. Check air supply to solenoid valve 20FH-1.
A.A. Diff. pressure Low Auto transfer to Dist.
M/C is on FO and atomizing air differential pressure across main atomizing air compressor CA1 drops to 1.3 bar sensed by pressure switch 63AD-1.
Alarm + changeover from FO to HSD
Main atomizing air compressor is not developing sufficient pressure or pressure switch 63AD-1 is faulty.1.38 ± 0.13 INCR-CLOSE1.03 ± 0.06 DEC- OPENNORMAL = NO
Check atomizing air system, main atomizing air compressor and call I&C people to check the pressure switch 63AD-1. Inform mechanical section to check the operation of main atomizing air compressor.
Cont….Indication Sensor & settings
Result
Cause Action Required
Liquid fuel temp. low
FO selection is made but HSD temperature is not ≥ 46°C for 3 minutes at filtration skid sensed by temperature switch 26FD-2.
Alarm
HSD temperature controller MBN40DT001 is not functioning properly to route the HSD through FO-HSD heat exchanger. FO temperature is not sufficient to heat the HSD. Fuel changeover command is given too early.
Check the fuel temperature, temperature switch and its set point. Check the proper operation of fuel heating system (heater, temperature switches, and electrical supply).
Auto Transfer to Dist. Communicator Failure
<C> communicator fails when M/C is running on FO
Change over from FOto HSD
Failure of <C> communicator. Convert M/C to Gas after running on HSD for 4 minutes. Call I&C people to attend the fault.
Cont….Indication Sensor &
settings ResultCause Action Required
Liquid fuel temp. low
FO selection is made But HSD temperature is not ≥ 46°C for 3 minutes at filtration skid sensed by temperature switch 26FD-2.
Alarm HSD temperature controller MBN40DT001 is not functioning properly to route the HSD through FO-HSD heat exchanger. FO temperature is not sufficient to heat the HSD. Fuel changeover command is given too early.
Check the fuel temperature, temperature switch and its set point. Check the proper operation of fuel heating system (heater, temperature switches, and electrical supply).
Liquid fuel control fault
Due to any of following faults:1. Liquid fuel Reverse Flow2. Liquid fuel flow Fault3. Liquid fuel valve servo current fault4. Liquid fuel valve loss of position Feedback5. Liquid fuel valve
open fault
M/C will trip during start Sequence before ignition.
Liquid fuel checking system has detected an abnormal servo or LVDT position or signal.
Determine abnormal condition by reading signal L3FLT1 to L3LFT3 on panel CRT display.
Cont….
Start-up fuel flow excessive trip
Excess fuel during start-up1. HSD flow is 1.58Kg/sec (5.688 T/h) before 40% speed and before turbine warm-up time is completed. This is not true during heavy purge.
(2) Gas flow is 28.6% FSGR before flame establishes.
M/C will trip during start Sequence.
Excessive fuel for start-up has been detected. For gas fuel the gas control valve is open too far.
Call I&C people to check the servo and feed back signals for proper operation. With liquid fuel: check tripping set point and fuel loop system operation. With gas fuel : check setting value of L.V.D.T. when valve is closed and the calibration of the V.S.R.
Liquid fuel stop valve failure to
open
15 seconds after liquid fuel stop valve does not open while hydraulic oil supply pressure is normal and open command is initiated.
ALARM Fuel oil stop valve takes a long time to open
Call I&C people to check proper operation of stop valve and of the trip oil circuit.
Distillate filter
diff pressure high (Downstream
)
Differential pressure of HSD filter at filtration skid is 1.5 bar sensed by pressure switch 63LF-2D (MBN10CP005).
ALARM Filter is dirty. Check local differential pressure and get the filter cleaned after taking stand-by filter in service.
Cont….
Indication Sensor & settingsResult
Cause Action Required
Feeding pipe purge running
When purge valve MBN60AA002 is opened sensed by limit switch 33PUR.
Alarm (indicates purging of FO feed line is in Progress)
Opening of FO feed line purge valve during first part purge.
Watch sump tank level during purge process.
Heavy fuel temp high
2 seconds after FO temperature is ≥115°C↑ in filtration skid at filters inlet sensed by temperature switch 26FU-3 (MBN70CT005).
M/C will change from FO to HSD on auto.
Wrong operation of FO temperature control valve EGC53DT001 at forwarding skid.
Check fuel temp. Check temp switch. Check proper operation of fuel heating system (heater, temperature switches).
Cont….
No additive flow, transfer to distillate or Shutdown
No additive flow sensed
by flow relay 86FST.
Fuel Changed from HSD to FO will be Prohibited if there is no flow of additive.
If M/C fails to convert on HSD within 10 seconds, it will be shut down.
Failure ofadditive dosing systemor wrong operation of flow switch.
Check indications on additive dosing panel and take appropriate action.
Cont….
Heavy fuel transfer permissive trouble
60 seconds after heavy fuel selectionis made but some ccondition is notfulfilled forchangeover.
Alarm
1. FO temperature is <90°C or
>115°C.
2. FO pressure is <4.5 bar at filtration skid.
3. Atomizing air differentialpressure is <1.03 bar.
4. Additive dosing system is not available.
5. FO pressure is <6 bar at forwarding skid.
6.FO forwarding pumps suction pressure is <-0.5 bar.
7. HSD temperature does not remain ≥46°C for 3 minutes.
During fuel changeover, thisindication appears usually due tolow temperature of HSD and resetsafter L26FD2L becomes logic 0. Ifthis is not the case find what permissive is missing and take appropriate action.
Heavy fuelfilter diffpressure high(downstrea)
Differential pressureof FO filter atfiltration skid is 2.0bar sensed by pressureswitch 63LF-2U(MBN70CP002).
ALARM Filter is dirty. Check local differential pressureand get the filter cleaned aftertaking stand-by filter in service.
