Fuel oil is stored on board in four fuel oil storage tanks (No.1 and 2 port and No.1 and 2 starboard.) The H.F.O. is transferred to a fuel oil settling tank by the fuel oil transfer pump (when required.) After fuel oil has been transferred to the settling tank, any water or other sediment is drained off by using a self - closing test cock.
From the fuel oil settling tank, fuel oil is supplied direct to the auxiliary boiler H.F.O. system and is centrifuged in one of two H.F.O. purifiers to the F.O.
service tank. Fuel oil is supplied to the main engine and generator diesel engines from the fuel oil service tank, using the same fuel supply system. The main engine and three auxiliary engines are designed to run on H.F.O. at all times. One of the fuel oil purifiers will be running at all times, with the throughput balanced to match the fuel consumption of the main engines and generator diesel engines.
All outlet valves from all fuel tanks are remote quick closing valves with a collapsible bridge, which can be pneumatically operated from the fire control station. After being tripped from the fire control station the valves must be reset locally. Each tank is also fitted with a self-closing test cock to test for the presence of water and to drain any water present. Tundishes, under the self-closing test cock, drain any test liquid to the waste oil tank. All tanks and heaters are supplied with steam at 6 kg/cm2from the ship’s steam supply, with condensate flowing to the observation tank which is fitted with an oil detection unit.
A viscosity controller controls the steam supply to both H.F.O. supply heaters.
All fuel oil pipework is trace heated by small bore steam pipes laid adjacent to the fuel oil pipe and encased in the same lagging.
Heated and filtered fuel oil is supplied to the main engine and auxiliary engines from the fuel oil service tank. Fuel oil from the fuel oil service tank is supplied to one of two fuel oil supply pumps. The second pump will be on automatic stand-by, and will start in the event of discharge pressure drop or voltage failure of the running pump. The F.O. supply pumps discharge through the auto back flush filter to the F.O. return pipe. The auto back flush can be bypassed with a basket filter during maintenance on the main filter. The filter is an automatic self-cleaning filter with an air operated cleaning mechanism activated by an increasing differential pressure. The debris discharge from the auto filter is piped to the fuel oil overflow tank. A pressure control valve maintains the supply pumps discharge pressure by recirculating oil from the pump discharge back to the pump suction.
Fuel oil is drawn from the return pipe by one of two main engine fuel oil circulating pumps. The second pump will be on automatic standby, and will start in the event of discharge pressure drop or voltage failure of the running pump. The fuel oil circulating pumps discharge through one of a pair of main engine fuel oil heaters where the oil is heated to a temperature corresponding to a viscosity of 12cSt using steam at 6 kg/cm2.
The heated fuel oil then passes through the viscosity controller which controls steam to the heater. The oil is supplied to the main engine fuel rail via the suction side of the main engine high pressure fuel oil injection pumps through a duplex filter and flow meter. A control valve regulates the pressure at the main engine rail, diverting excess pressure to the return pipe through a flow meter. A three-way cock is fitted on this section of line to flush the system back to the service tank when changing over to diesel oil when at standstill.
The high pressure fuel oil lines on the engine are sheathed. Any leakage from the annular spaces, formed by the sheathing, is lead to a fuel oil leakage tank, which is fitted with a high level alarm and gives advance warning of a leaking fuel injection pipe.
Preparation for the Operation of the Main Engine Fuel Oil Service System
a) Put the H.F.O. purifier in use, filling the service tank from the settling tank.
b) Ensure that the filters are clean.
c) Ensure that all instrumentation valves are open.
The following procedure illustrates starting from cold with the system charged with diesel oil and in a shut down condition.
Set up the valves as in the following table:
Position Description Valve
Open Service Tank Suction Quick Closing Valve RR6 Open Service Tank Secondary Suction Valve RR43
Closed Diesel Oil Tank Suction Valve RR17
Closed Diesel Oil Suction Valve RR44
Set for H.F.O. Suction Three Way Change Over Cock Open No.1 Supply Pump Suction Valve Open No.1 Supply Pump Discharge Valve Open No.2 Supply Pump Suction Valve Open No.2 Supply Pump Discharge Valve
Open Pressure Control Valve Inlet Valve Open Pressure Control Valve Outlet Valve Closed Pressure Control Valve Bypass Valve Open Backflush Filter Inlet Valve
Open Backflush Filter Outlet Valve Closed Bypass Filter Inlet Valve Closed Bypass Filter Outlet Valve
Open No.1 H.F.O. Circulating Pump Suction Valve Open No.1 H.F.O. Circulating Pump Discharge Valve Open No.2 H.F.O. Circulating Pump Suction Valve Open No.2 H.F.O. Circulating Pump Discharge Valve Open No.1 H.F.O. Heater Inlet Valve
Open No.1 H.F.O. Heater Outlet Valve Closed No.2 H.F.O. Heater Inlet Valve Closed No.2 H.F.O. Heater Outlet Valve Open Viscosity Controller Inlet Valve Open Viscosity Controller Outlet Valve Open Viscosity Controller Bypass Valve Open Main Engine Flow Meter Inlet Valve Open Main Engine Flow Meter Outlet Valve Closed Main Engine Flow Meter Bypass Valve
Open M.E. Master H.F.O. Inlet Valve RR1
Open M.E. Outlet Valve RR2
Open M.E. Control Valve Inlet Valve RR79
Closed Inlet Valve to Service Tank RR4
Open Return Flowmeter Inlet Valve Open Return Flowmeter Outlet Valve Closed Return Flowmeter Bypass Valve Set Return Change Over Cock to the Return Pipe
Illustration 2.6.1a Main Engine Fuel Oil Service System.
RR2
RR1
RR78 RR79
PI
PI
PT
PI PI PS RR6
RR17
RR44
RR43
RR4
PDE POS
Heater
F.O. Heater
Viscocity Unit Flowmeter
Auto Filter
Steam From 7kg/cm2 System
TI TI M TI
TI
TI PI
PS
PI PS PDIS
LAL
To Overflow Tank
From Control Air
System
F.O. Heater
M
M
To Atmosphere Condenser
To Auxilliary Engines From Auxilliary
Engines
Key
Marine Diesel Oil Fuel Oil
Saturated Steam Air
Condensate Main
Engine B & W 5S 50MC D.O.
Service Tank
LAL
H.F.O.
Service Tank
TAH LAL
Deaerator F.O.
Circulating Pumps
5m3/h
F.O.
Supply Pumps 4m3/h
(33 m3) (38 m3)
Procedure to start up the Main Engine HFO Service System and change over to H.F.O.
a) Supply steam heating to H.F.O. service tank.
b) Open all the individual fuel inlet valves on the M.E. fuel inlet main.
c) Supply trace heating to the fuel oil service system pipelines.
WARNING
Trace heating should not be applied to sections of pipeline isolated by closed valves on the HFO side as damage could occur due the expansion of the contents.
d) Manually start supplying steam to the on line H.F.O. heater.
e) Start one fuel oil supply pump.
f) Start one H.F.O. circulating pump.
g) Raise the temperature to about 75ºC.
h) Start the viscosity controller and close the bypass valve.
i) Open the inlet valve to the H.F.O. service tank RR4.
j) Operated the return change over cock to direct the return H.F.O.
to the service tank.
k) D.O. will now be expelled to the H.F.O. service tank, at the same time drawing in H.F.O. from the service tank.
l) Continually raise the temperature manually.
m) When the set point is reached on the viscosity controller, change its setting to auto.
n) Change the operation of the steam control valve to auto. Open the steam inlet valve fully.
H.F.O. is now circulating through the system.
o) Supply steam heating to the H.F.O. return pipe.
p) Switch the other H.F.O. supply pump to standby.
q) Switch the other H.F.O. circulating pump to standby.
Set the change over return cock back to the return pipe.
Fuel Change Over
The main engine is designed to run on H.F.O. at all times. However, change over to diesel oil can become necessary if, for instance, the vessel is expected to have a prolonged inactive period with a cold engine, i.e. due to:
A major repair of the fuel oil system etc A docking
More than five days stoppage
Environmental legislation requiring the use of low sulphur fuels Change over can be performed at any time, during engine running or during engine standstill.
In order to prevent fuel pump and injector sticking/scuffing, poor combustion, and fouling of the gas ways, it is very important to carefully follow the change over procedures.
Change Over from Diesel Oil to Heavy Fuel Oil During Running
To protect the injection equipment against rapid temperature changes, which may cause sticking/scuffing of the fuel valves and of the fuel pump plungers and suction valves, the change over is carried out as follows (manually):
a) First, ensure that the heavy oil in the service tank is at normal temperature level.
b) Reduce the engine load to 75% of normal. Then, by means of the thermostatic valve in the steam system, or by manual control of the viscosity regulator, the diesel oil is heated to maximum 60-80ºC, in order to maintain the lubrication ability of the diesel oil and this way minimises the risk of plunger scuffing and the consequent risk of sticking. This preheating should be regulated to give a temperature rise of about 2ºC per minute.
c) Due to the above mentioned risk of sticking/scuffing of the fuel injection equipment, the temperature of the heavy fuel oil in the service tank must not be more than 25ºC higher than the heated diesel oil in the system (60-80ºC) at the time of change over.
(Note ! The diesel oil viscosity should not drop below 2cSt, as this might cause fuel pump and fuel valve scuffing, with the risk of sticking.)
d) For some light diesel oils (gas oil), this will limit the upper temperature to somewhat below 80ºC. When 60-80ºC has been reached, the change to heavy oil is performed by opening the fuel oil supply valve RR43. Turn the change over cock on the suction side of the H.F.O. supply pumps to take suction from the H.F.O.
service tank. Close diesel oil supply valve RR44.
The temperature rise is then continued at a rate of about 2ºC per minute, until reaching the required viscosity.
Change Over Procedure from Heavy Fuel to Diesel Oil During Running To protect the fuel oil injection equipment against rapid temperature changes, which may cause scuffing with the risk of sticking of the fuel valves and of the fuel pump plungers and suction valves, the change over to diesel oil is performed as follows (manually):
a) Ideally the diesel oil in the D.O. service tank should be about 50ºC.
b) Shut off the steam supply to the fuel oil preheater, return fuel pipe and steam tracing.
c) Reduce the engine load to 75% of MCR load.
d) Change to diesel oil when the temperature of the heavy oil in the preheater has dropped to about 25ºC above the temperature in the diesel oil service tank, however, not below 75ºC.
e) Open diesel oil supply valve RR43. Change over the supply three way cock to the D.O. service tank. Close H.F.O. supply valve RR43.
Fuel oil is now led to the supply pumps.
(Note ! If, after the change over, the temperature (at the preheater) suddenly drops considerably, the transition must be moderated by supplying a little steam to the preheater, which now contains diesel oil.)
Change Over Procedure from Heavy Fuel to Diesel Oil During Standstill a) Stop the preheating.
b) Stop trace heating.
c) Stop return pipe heating.
With regard to temperature levels before change over, see ‘Change Over from Heavy Fuel to Diesel Oil during Running’.
d) Open diesel oil supply valve RR44.
e) Change over suction changeover cock.
f) Close fuel oil supply valve RR43.
g) Open inlet valve to service tank RR4.
Illustration 2.6.2a Auxiliary Engine F.O. Service System
To Main Engine B&W 5S-50MC
Saturated
Marine Diesel Oil Fuel Oil
h) Change over the return cock to the H.F.O. service tank, so that the fuel oil is flushed to the H.F.O. service tank. Ensure that there is sufficient ullage in the service tank.
i) When the heavy fuel oil is replaced by diesel oil, reset the change over cock and close valve RR4
j) Stop the viscosity controller.
k) Stop the fuel oil pumps.
2.6.2 Auxiliary Engine Fuel Oil Service System
Operation Using H.F.O.
Fuel oil is supplied to the generator diesel engines from the fuel oil service tank, using the same supply system as the main engine system. The three auxiliary engines are designed to run on F.O. at all times. However, one auxiliary engine should be ready to run on D.O. in case a failure occurs within the main H.F.O. supply unit.
Heated and filtered H.F.O. is supplied to the auxiliary engines from the same point as the main engine, which is just after the viscosity controller. The H.F.O.
then flows through a flowmeter to the auxiliary engines
The auxiliary engines have three-way cocks at the fuel inlet and outlet for the selection of either H.F.O. or D.O.
Excess H.F.O. is returned to the H.F.O. return pipe via a flowmeter and three-way cock. The three-three-way cock can divert the fuel to the service tank for flushing purposes.
The high pressure fuel oil lines on the engine are sheathed and any leakage from the annular spaces, formed by the sheathing is led to a fuel oil leakage tank fitted with a high level alarm which gives advance warning of a leaking fuel injection pipe.
Operation Using D.O.
The auxiliary engines can be supplied from the diesel oil service tank using the D.O. supply pump. The pump pressure is controlled at 5.5 kg/cm2. The return pressure is controlled at 4.5 kg/cm2 with excess D.O. returned to the D.O.
service tank.
Procedure for the Operation of the Auxiliary Engine Fuel Oil Service System
a) Put the H.F.O. purifier in use, filling the service tank from the settling tank.
b) Ensure that the filters are clean.
c) All engines are stopped.
d) Ensure that all instrumentation valves are open.
e) Start up the main H.F.O. system as described previously.
f) Supply trace heating to the auxiliary fuel oil service system pipe lines.
The following procedure illustrates starting from cold with the system charged with diesel oil and in a shut down condition:
g) Start No.1 auxiliary engine using D.O.
h) Set up valves as in the following table.
Position Description Valve
Open Inlet Flow Meter Inlet Valve Open Inlet Flow Meter Outlet Valve Closed Inlet Flow Meter Bypass Valve Open Outlet Flow Meter Inlet Valve Open Outlet Flow Meter Outlet Valve Closed Outlet Flow Meter Bypass Valve
Set for HFO No.2 A.E. Outlet Three-way Cock RR19 Set for HFO No.3 A.E. Outlet Three-way Cock RR22 Set for HFO No.2 A.E. Inlet Three-way Cock RR32 Set for HFO No.3 A.E. Inlet Three-way Cock RR31 i) Using the bypass valves RR25 & RR24 warm up the H.F.O.
system by flushing the system back to the return pipe.
j) No.2 and 3 engines are ready for starting on H.F.O.
Procedure to Prepare an Auxiliary Engine (No.1) for Running on D.O a) Transfer D.O. from the D.O. settling tank to the D.O. service tank
using the purifier.
b) Set up valves as in the following table.
Position Description Valve
Open D.O. Service Tank Outlet Valve RR10
Open D.O. Pump Suction Valve RR11
Open D.O. Pump Discharge Valve RR12
Closed D.O. Pump Bypass Valve RR13
Set to D.O. Inlet Three-Way Cock RR33
c) Start the D.O. supply pump.
d) If previously operated on H.F.O., open Valve RR17 long enough to flush the system back to the return pipe.
e) Set the outlet three-way cock RR15 to D.O.
The engine is now ready for starting on D.O.
Changing Over Fuel when Auxiliary Engine(s) Are Running
Procedures similar to that used for the main engine could be used, but it would be more advisable to change over the fuel supply when the vessel’s power is being supplied by an auxiliary engine running on D.O. supplied by the D.O.
fuel pump and system.
Auxiliary Boiler
D.O. Service Tank
H.F.O. Settling Tank Air
Separator
PI
PI
PI TI No.1
RR64 RR71
RR63 LAH TAH LAL RR69 LAL
RR41
PI RR42
PS TS
TS
PS PI
PI PI PI
TI
PI
PI TI
TT
PI PC Heater
No.1 RR60
RR68 RR40
RR38
RR37
RR67
RR36
RR35 RR39
No.2 H.F.O.
Pump Unit
RR48
RR49 RR57 RR47
TI
Illustration 2.6.3a Auxiliary Boiler Fuel Oil Service System
Saturated Steam
Electrical Signal T/S
Burner Unit For Boiler
Ignition Oil Pump
Marine Diesel Oil Fuel Oil Key
2.6.3 Auxiliary Boiler Fuel Oil Service System
Fuel oil is stored on board in four fuel oil storage tanks, and then (when required) transferred to a fuel oil settling tank by a fuel oil transfer pump. After fuel oil has been transferred to the settling tank, any water or other sediment is drained off, using the self-closing test cock. Fuel oil is supplied directly to the boilers from the fuel oil settling tank.
Diesel oil can be supplied to the boilers from the diesel oil service tank when starting from cold.
A temperature controller maintains the steam supply to the F.O. heater. All the fuel oil piping is trace heated by small bore steam pipes. These are laid adjacent to the fuel oil pipe and encased in the same insulation.
Fuel oil from the fuel oil settling tank is supplied to one of two fuel oil pumps.
The second pump will be on automatic standby, and will start in the event of a discharge pressure drop or a voltage failure of the running pump. The fuel oil pumps take suction from the settling tank via a strainer. A pressure control valve, with its sensing point on the heater discharge, maintains the pump discharge pressure by recirculating oil from the pump discharge back to the air separator/return pipe. The oil in the return pipe returns to the pump suction.
The vent from the air separator returns to the H.F.O. settling tank.
The fuel oil pumps discharge through one fuel oil heater, where the oil is heated to the required temperature.
The oil is fed to the boiler via a pressure-control valve, controlled by the boiler steam pressure. When the boiler is in a standby condition, a solenoid valve on the return line automatically opens to circulate fuel back to the return pipe, keeping the fuel oil at working temperature immediately before the burner. On the recirculating line is a change over cock, where the fuel can be diverted from returning to the return pipe to either the H.F.O. settling tank or D.O. service tank. This change over cock would normally be used for flushing fuel oil back to the H.F.O. tank when changing from D.O. to H.F.O. or vice versa.
The boiler has a pilot burner pump, which takes suction from the D.O. service tank via the pump suction filter.
A steam connection is fitted to the F.O. line to the burner after the double shut off solenoid valves and is used for automatic purging of the burner prior to shut
A steam connection is fitted to the F.O. line to the burner after the double shut off solenoid valves and is used for automatic purging of the burner prior to shut