Engineers must be well conversant with fuel oil and lube oil installation onboard and various associated functions such as bunkering ,transfer, purification ,combustion and disposal . Fuel oil are carried in tanks in the vicinity of the engine room. For daily use oil is first transferred by the transfer pump to the settling tank and then brought through purifier clarifier to the service tank.
Fuel oil is then handled by the supply and circulating pump and finally by the fuel injection pump . All pump, filter ,heaters and purifiers are in duplicate with change over arrangement to ensure non stop service .
Separate service tanks are provided for Diesel oil and boiler Fuel oil. Tanks are also provided for receiving overflow, drain oil and dirty oil and sludge. Sludge may be disposed of by burning in the incinerator or by pumping to the Shore reception facility .
Leakage into the bilge is prevented by use of drip tray under various equipment.
Steam heating coils are provided in all tanks to reduce viscosity before pumping .Steam heaters are used before the fuel oil is used for combustion engine or boiler. Steam traps are provided on the return line of the steam line, so that the latent heat in the steam is fully utilised and only condensate Water Return To The Hot Well. In case of any leak in the steam coil ,may find its way into the hot well and then to the boiler ,to avoid this contamination condensate is lead to an observation tank where oily is separated and then and can be seen through sight glass . Watch the tank regularly if oil is found on the surface it should be led to the drain oil tank by opening appropriate valve. Leaky coil is identified and isolated to prevent for the furthur contamination. While heating temperature of the oil should not be more than 10 degree Celsius below the flash point.
Oil tanks are provided with overflow pipes leading to the overflow tank. There is no valve on this lines . Ensure that the overflow tank is empty during starting bunkering or oil transfer. Watch the sight Glass on the overflow line. Stop filling the particular tank if oil is seen in the glass. Air vent of the tanks are above the level of the overflow pipes. Wire mesh are fitted to the air vent to act as heat and Flame arrestor .outlet valve of all tanks other than those below the engine platform are of quick closing valve type with arrangement to close them from a position outside the engine room. this valves should be periodically tried out . Drain valves are of self closing spring loaded type they remain open only till the operator press the handle. sounding pipes for tanks below the engine room are fitted with weighted cock .
BUNKERING
-The bunkering plan should be displayed at the bunkering station . Study the SOPEP manual and take precaution to avoid oil spillage on the Deck and into the sea . Record sounding at all times . Overflow tank must be empty. Decide the quantity to be taken and tanks to be filled. Maintain communication with the shore bunkering station and duty officer. Keep firefighting appliances in readiness. Connect the Shore pipeline to the bunkering land with proper joint between flanges . Open appropriate valves and start receiving the oil. Do not fill the tank to full capacity as there maybe possibility of overflow. If one tank is nearly full ,open the valve for another tank before closing the valve of the first tank . Inform the shore station to stop pumping when the required quantity is taken on board . At the end blow through the pipeline to remove the remaining oil . Keep taking sounding of the tank to ensure proper flow to the desired tank. Determine the quantity of oil received on board . Take sample of oil while receiving Bunker and seal the bottle for use in case there is any dispute later. Note the property of oil particularly specific gravity ,viscosity , Flashpoint, calorific value ,sulphur content ,pour point, ash content etc. Test certificate issued by an independent accreted agency is accepted after the Shore pipe is disconnected . Blank the bunkering connection
Oil transfer
Ship fuel oil transfer pumps are used for transfer oil from one tank to another . separate pumps are used for heavy oil and diesel oil . Daily routine includes transfer a fuel from bunker tank to the settling tank by the fuel oil transfer pump and then from the settling tank to service tank through the purifier . This tanks are in duplicate and arranged transversely while transferring there should be a minimum effect on the list of the ship. Screw or gear pump ars used for oil transfer this are positive displacement pump and hence should not be started with discharge valve closed . Pressure regulating valve are fitted on this pump that maintain constant pressure on the discharge side access oil is returned to the suction side for recirculation. Efficiency of the pump depends on the radial and axial clearance of the gear or screw in the casing . Pumps can be stopped by pressing emergency control located outside the engine room .
Plain wire mesh cartridge Turbo and autofilter auto clean filter used. Cartridge require cleaning regularly . Auto clean filter are cleaned while in use by turning the knob on top of the cover . Impurities collected the bottom of the casing can be removed by opening the bottom plug, when the oil circulation in stopped . For change over of filter there is a motor mechanism which rotate the filter arrangement from 1st to 2nd filter and air valve is opened to wash the 1st filter and then close the air valve. Now 2nd filter is in use and 1st one is isolated . Timing of operation of motor is controlled by the pressure difference between inlet and outlet of the auto back wash filter. If the difference is more than the motor operates and auto changeover from 1st filter to 2nd filter take place ,with washing of 1st filter and 2nd filter in use.
Oil purification
Oill is first pumped into the settling tank and stay there for about 12 hours. Water settles down to the bottom of the tank from where it can be removed by operating drain valves . Oil then passes through centrifugal purifier to remove water and sludge . Clean oil passes to the service time for use in the engine. Gravity disc in the purifier is chosen according to the seperation gravity of the oil .
Fuel oil routines
Fuel oil consumption is recorded from noon to noon from the flow metres and service tank sounding. As a routine service tanks are normally change over at noon. A typical routine for filling the tank and keeping them ready for the next day is given below
1. At 12 noon note sounding of both service tank. ensure that the tank is treated to about 80 degree Celsius and there is no water in the oil. check by opening drain valve.
SOME IMPORTANT POINTS
1. Settling tank fuel oil can also be sent to fuel oil supply unit of engine that is to the f.o supply pump .check no 1 valve in diagram.
2. No 1 HFO purifier supply pump can send fuel oil to no 2 HFO purifier Heater and vice versa.check no 3 valve in diagram
3. HFO Purifier heater can be bypassed and can directly send oil to purifier .check no 2 valve
4.we can bypass the HFO purifier heater and can send oil directly to settling tank if suppose there is a problem in heater. Check no 4 valve in diagram.
5. No 1 and No 2 fuel oil supply pump and circulating pump for G.E and M.E can be auto change over if pressure in the system falls.
6.In between fuel oil supply pump and f.o circulating pump there is a relief valve to maintain a desired pressure at outlet of both the pumps.
7.In steam line ,outlet line all steam valve are of non return type and thus have y type stream trap with strainer and cock.
8. HFO auto filter (35micron), they are turned by turning the spindle.
9. The oil return from ME and GE goes into the cock which diverts the oil to venting box or service tank. See diag
10.From venting box oil goes to the suction side of circulating pump at pressure of 6 bar.
11. Supply pump pressure is 4 bar and circulating pump pressure is 6 bar.
12. Venting box has automatic deaerating valve ,the venting of HFO goes through a sight glass and is drained to overflow tank. Thus there is prevention of air lock into the fuel oil system which can be due to dissolved water in fuel or from the supply pump suction side.
13. All supply and circulating pump has safety valve to lift.
14. The discharge line of safety valve is connected to suction line of that pump.
15.Fo high pressure pipe leakage alarm (high leakage drain box alarm level)
16. The return oil from fuel valve and pump is led back to the venting box and then to the suction side of circulating pump.
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