Post on 28-Nov-2014
P.Kumar, Lecturer/Dsl
FUEL OIL SYSTEM
FUEL OIL SYSTEM OF FUEL OIL SYSTEM OF WDM2 LOCOWDM2 LOCO
Requirements of fuel system.Associated components of fuel system.Schematic Diagrams of fuel oil system.Fuel efficient kits of fuel oil system.Trouble shooting of fuel oil system.
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REQUIREMENT OF FUEL SYSTEM
The fuel oil system is designed to introduce fuel oil in to the engine cylinders at correct time ,in correct quantity and at correct pressure.
At correct time: The fuel should be introduce in to the combustion chamber within precisely
defined period of the cycle.
Fuel injection start- 18º 15' before TDC
Termination of injector– 14º 45'After TDC
Total Period of injection -18º 15'+14º 45'=33º
CORRECT QUANTITY-CORRECT QUANTITY-..Correct quantity of fuel is Correct quantity of fuel is important to maintain the variable speed of important to maintain the variable speed of locomotive engine at variable load.locomotive engine at variable load.
Usually, The distribution of the fuel among Usually, The distribution of the fuel among each cylinder is done uniform.each cylinder is done uniform.
CORRECT PRESSURECORRECT PRESSURE: : High pressure also helps inHigh pressure also helps in proper atomization proper atomization so that the small droplets come in so that the small droplets come in
better contact with the fresh air in the combustion better contact with the fresh air in the combustion chamberchamber
High pressure of fuel is required High pressure of fuel is required to lift the nozzle to lift the nozzle valve and for better penetration of fuel in to valve and for better penetration of fuel in to combustion chambercombustion chamber
The beginning and the end of The beginning and the end of injection should be injection should be sharpsharp,i.e there should not be any dribbling or after,i.e there should not be any dribbling or after injection. injection.
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PUMP
PRIMARYFILTER
SECONDARYFILTER
Rt. FUEL OIL HEADER RE
GU
LA
TIN
GV
AL
VE
4.2
Kg/
cm2
RELIEF VALVE5.3 Kg/cm2
FOP Gauge
FUEL OIL SYSTEM - WDM2
LEAK OFF HEADER
FIP
Injector
MOTOR
Fuel tank
Lt. FUEL OIL HEADER
Cross Over Pipe
The fuel oil system consists two integrated system.The fuel oil system consists two integrated system.
(A)(A) Fuel feed system.Fuel feed system.
(B)(B) Fuel injection systemFuel injection system..
(A)(A) Fuel feed systemFuel feed system:- The fuel feed system provides the :- The fuel feed system provides the back up support to the fuel injection pump by back up support to the fuel injection pump by maintaining steady supply of fuel at required pressure.maintaining steady supply of fuel at required pressure.
(B)(B) Fuel injection systemFuel injection system:- The Fuel injection pump :- The Fuel injection pump started according to firing order. All F.I.P start & started according to firing order. All F.I.P start & discharging fuel oil at high pressure to their respective discharging fuel oil at high pressure to their respective nozzle.nozzle.
Associated Components(Fuel feed system)-Associated Components(Fuel feed system)-
(a)Fuel oil tank-Fabricated under the super structure of locomotive and (a)Fuel oil tank-Fabricated under the super structure of locomotive and located between two bogies.Capacity-5000ltslocated between two bogies.Capacity-5000lts
(b)Fuel primary filter-(paper type filter)(b)Fuel primary filter-(paper type filter)
(c )Booster pump(fuel transfer pump)(c )Booster pump(fuel transfer pump)
Pump capacity- 14 lts/ minutes(at 1725 rpm)Pump capacity- 14 lts/ minutes(at 1725 rpm). pressure-4-4.8 kg/cm2. pressure-4-4.8 kg/cm2
(d)Fuel relief valve-The spring loaded relief valve( (d)Fuel relief valve-The spring loaded relief valve( . Adjusted at-5kg/cm2(70 p.s.i). Adjusted at-5kg/cm2(70 p.s.i)(e) Fuel secondary valve- (Paper type filter )(e) Fuel secondary valve- (Paper type filter )
(f)Fuel regulating valve-The spring loaded valve(f)Fuel regulating valve-The spring loaded valve. Adjusted at- 4.0 to 4.2kg/cm2(50-55p.s.i). Adjusted at- 4.0 to 4.2kg/cm2(50-55p.s.i)
Associated components( Fuel Injection system)
A.Fuel injection pump- It is single acting constant stroke plunger type pump
Function- a.To raise the fuel oil pressure to nozzle which will efficiently atomize the fuel.
b.To supply the correct quantity of fuel to nozzle as per power and speed requirement of the engine.
c.To accurately time the delivery of the fuel for efficient economical operation of engine.
B.Fuel injection nozzle-a.To inject fuel at a sufficiently high pressure so that the fuel enters the cylinder with a high velocity
b.Fuel injection nozzle injects fuel oil to combustion chamber at 4000psi.
Fuel injection pump
Some important parts of FIP are as below-
1. Control Rack2. Barrel & plunger3. Control sleeve4. Plunger spring 5. Guide cup6. Lower spring seat.7. Snubber valve assembly.
Calibration of FIPCalibration of FIPPurpose: It is done after overhauling to ensure that it
delivers the same and stipulated amount of fuel at a particular rack position.
Process of FIP calibration & testing The calibration and testing of FIPs are done on a specially designed
machine. The blended test oil of recommended viscosity under controlled
temperature is circulated through a pump at a specified pressure for feeding the pump under test.
The oil discharged for 300 stroke of the pump is measured at idle and full load. For WDM2,it is as –
9mm rack position(idle) - 34 CC +1/-5
30 mm rack position (Full load ) - 351 CC +4/-11 If test results are not within limit ,adjustment of fuel rack position is
done by moving the rack pointer with addition or removal of shims behind it.
PHASING & CALIBRATION OF FIP
•PHASING: Setting of Pump according to Injection Timing
•CALIBRATION: Calibrating delivery of the pump according to Rack Position
Checked by hartridge 1100 calibrating machine at 300 rpm and 300 stroke
9mm = 45 ml
28 mm= 401 ml
Fuel injection nozzle
Some important parts of fuel injection nozzle are as below-
1. Nozzle body2. Nozzle Valve3. Spacer4. Pressure adjusting spring5. Nozzle holder body.6. Cap nut
Testing of Fuel Injection Nozzle Testing of Fuel Injection Nozzle Purpose:Good atomization ,correct spray pattern
and no leakage or dribbling are the criteria of a good FIN.
The following tests are conducted on a specially designed machine-
Spray pattern( by taking impression on blotting paper)
Spray pressure (3900-4050 PSI for new & 3700-3800 PSI for reconditioned nozzle)
Dribbling : This occur due to improper pressure setting or dirt stuck up between the valve & valve seat. Or improper contact between the valve and valve seat.
TESTING OF NOZZLE•Opening Pressure: 3900-4050 psi (New), 3700- 3800 psi (Old)
•Spray Pattern/ Blotter test: Uniform pattern
•Dribbling: Holding at 3500 PSI for 10 secs ( No drop)
•Leak off: 3500 to 1000 PSI drop down time 6-16 secs
•Valve Lift: .026" (max), .005 to .007" (New)
Continue…Continue… Nozzle chatter: This sound creates due to
free movement of the nozzle valve inside the valve body. it should be proper.
Nozzle leak off rate: the process of checking the leak off rate is by creating pressure in nozzle up to 3500 PSI and hold the pressure till it drop to 1000PSI.( 5sec)
ORIFICE TEST ORIFICE TEST Purpose: This test is conducted to check
the efficiency of the fuel feed system under full load condition.
Process: Fit a orifice plate of 1/8 inch in the system
before the regulating V/V. Place a container to collect the leak off oil. Switch on the Fuel booster P/P for 60 sec. The rate of leak should be about 9 ltrs per
minute.
FUEL EFFICIENT KITFUEL EFFICIENT KIT
PURPOSEPURPOSE- To improve specific fuel consumption by - To improve specific fuel consumption by 6%,Reduction in existing exhaust gas temp by 1006%,Reduction in existing exhaust gas temp by 100ººand and
reduction in lub oil consumption.reduction in lub oil consumption.
1.Modified water connection to after cooler -Water inlet of the after cooler is connected from outlet of the radiator to provide water at min. possible temp into the after cooler.
2.17 mm fuel injection pump-15 mm pumps are replaced by 17mm pump to have sharper fuel injection.Max rack. it has increased injection rate also.
3.Modified cam shaft with 140 degree over lap-The cam shaft increase the over lap from 123 to140 degree to improve the scavenging.
4.Larger after cooler-increased core size, Introduced four passes instead of two passes,it has increased the effectiveness of after cooler to over 25%. Higher effectiveness has been introduced to provide cooled air to engine.5.Steel cap pistons-In the fuel efficient engine ,peak firing –1800 psi ,lower lub oil consumption. steel cap piston provides greater strength compared to the all AL pistons used earlier.6.High efficiency turbo charger-High efficiency turbo super charger ABB -VTC 304, NAPIER NA295 having capacity to develop 2.2kg/cm2 booster pressure.
MOVE THE NATIONDLW OUR LOCOS
Successive Power Upgradation and Specific Fuel Consumption reduction
HP/Cylinder
162.5
193.75
206.25
225
2600 HP
3100 HP
3300 HP
3600 HP
4500 HP
154
152
150
166
156
SFCgm/bhp-hr.
1960-90 90-2000 2001 - 08
Oct,1993
Oct,2001
Nov,2002
May,1990
Oct,1995
Nov,2002
TECHNOLOGY PROGRESSION
Reasons of low fuel oil pressureReasons of low fuel oil pressure
Due to insufficient fuel in fuel oil tank.(less than 700Ltrs)
Primary or Secondary filter may be choked. Defective Fuel booster pump & Motor. Wrong adjustment/Sticking of Relief valve. Due to fuel leakages in the system. Wrong adjustment/Sticking of Regulating
valve.
TROUBLES IN DIESEL ENGINE DUE TO FUEL OIL TROUBLES IN DIESEL ENGINE DUE TO FUEL OIL
The use of dirty and unsuitable fuel frequently causes the following troubles – Piston ring groove deposits- Dirty contaminated fuel oil is
responsible for gummy carbonaceous deposits in piston ring grooves which induce the rings to stick and causes Blow by, ineffective lubrication, Inefficient air compression ,Poor combustion, High fuel consumption and contamination of the crank case oil.
Exhaust valve deposit- Resulting in poor air compression, Poor combustion ,and high fuel consumption.
Cylinder wall deposit –it will interfere with the lub oil film and causes excessive metallic wear.
Fuel pump wear-Due to heavy close fit between the plunger and their barrel ,impurities may causes seizures, reduce the quantity fuel delivery per stroke .
TO ENHANCE RELIABILITY OF FOSTO ENHANCE RELIABILITY OF FOS
The following preventive actions should be taken to avoid loco failures on account of fuel oil system and to enhance their reliability-
Torqueing of FIP foundation bolts,T-jumper bolts and Banjo bolts are to done in sequence during fitment and it should to tightened to the recommended torque range.
It must be a normal practice to fit matched fuel injector, H.P pipe and FIP duly calibrated and tested on test bench during yearly schedule or if removed together.
• Check fuel oil P/P vacuum in every schedule .if less, P/P should be removed for overhauling .
• It loco is giving repeated problem of el oil pressure ,clean the fuel oil tank by filling up the water and draining out the same after opening dummy provided at bottom of the fuel tank.
Continue---Continue---Check distorsion of Banjo bolt and fit copper
washer of appropriate thickness in each removal.Primary/ Secondary filter must be replaced in due
time.Ensure only Zyglo tested High pressure tubes to
be fitted in loco.Ensure that clamping of all fuel hoses has been
done properly to avoid its rubbing.During overhauling of FIP, avoid excessive
clearance in barrel and plunger assembly to avoid fuel oil leakage from leak off hole which leads to its excessive consumption
Continue…Continue…Drain out water and Sludge from the fuel oil tank
of loco at least in every monthly schedule by opening drain cock of the fuel tank. (Must do, if loco is giving repeated problem of fuel oil pressure dropping)
Before turn out of loco from shed, ensure that strainer at fuel filling plug of fuel tank is not in distorted condition through which foreign material like cotton waste, cloth, rag , jute etc may block suction line to fuel booster pump.
FUEL OIL TESTS AND FUEL OIL TESTS AND SIGNIFICANCESSIGNIFICANCES
Water contamination (by Crackle test) Specific gravity (Co-relates with calorific value of fuel
so tested at 15’C) Viscosity ( Spray pattern affects) Flash point(Temp.at which it gives sufficient vapour to
form a mixture with air). Carbon residue. Sulphur content.( high sulphur contain may cause
corrosion in engine parts) Cetane number( indicate ignition quality ) Colour comparision (with potassium dichromate
solution)
TROUBLE SHOOTING OF FUEL OIL SYSTEMTROUBLE SHOOTING OF FUEL OIL SYSTEM A.Fuel oil pressure not building up.
B.Fuel pump motor not working.
C.Fuel pump contactor not picking up.
D. Oil leakage from fuel T jumper o ring.
E.T jumper cap screws worked out.
F.Fuel pump/support cap screw worked out.
G.Fuel oil primary/secondary filter chocked.
H.Fuel oil cross over pipe burst.
I.Fuel oil hose pipes burst/damaged due to rubbing.
J.Fuel oil leaking from hose pipe joint/union –defective.
K.Fuel oil contaminated with water.