1.2.3 DIESEL OIL SYSTEM

  DIESEL OIL SYSTEM

General Process system description:

Ships marine diesel engines run on Heavy Fuel Oil (HFO), nowadays a low sulphur content, or Marine Diesel Oil (MDO) or Marine Fuel Oil (MFO).

The diesel oil system has as its purpose,

  • Receiving        
  • Storage      
  • Purification and distribution of diesel oil to the various users on the FPSO.

The main function of the diesel oil system is to provide purified diesel oil to Topsides Main Turbo Generators (Package A/B/C) Port and Starboard (Package D/E/F),  Fire water pump Day Tank  (5-TA-  1710A/B/C/D),  Inert  Gas  generators  Day  Tank  5  TA  1210  A/  B  and  Hull  users Essential diesel generator DO day Tanks 4TA 6520A/B/C,  Emergency diesel generator DO day tank 4TA 6710, Life Boat  refuelling, Crew Boat refuelling and Fast Rescue Craft refuelling. In addition diesel oil is used for flow lines preservation before Start-up or during on-site operation for Topsides. 

 The diesel oil system consists of:

  • Raw diesel oil storage Tanks (4TA 1810 A / B, Capacity – 5000 m 3  )
  • Diesel oil over flow Tank (4TA 1840, Capacity – 50 m 3  )
  •  Diesel oil settling Tank (4TA 1850, Capacity – 830 m 3  )
  • Diesel oil Service Tank (FWD) (4TA 1820, Capacity – 480 m 3  )
  • Diesel oil Service Tank (AFT) (4TA 1830, Capacity – 480 m 3  )
  • Diesel oil Purifier Package (4UB 1880 A/B/C/D/E, Capacity – 12.5 m³/hr)

Diesel oil tanks shall be located in between the Machinery space area & the Cargo area in the Hull. All other equipment’s shall be installed in the machinery space area.

Loading the FPSO from supply vessel:

The raw diesel oil is received on to the FPSO from supply vessel into the raw diesel oil storage 
tanks Port & Starboard (4TA 1810A (Port) and 4TA 1810B (Starboard)) through bunker station. The raw Diesel Oil shall be  received  via  the  common  manifold  with  Shutdown  valve  4SDV  18113  connected  to  a dedicated line with dedicated 4ROV 18104A for tank 4TA 1810A and 4ROV 18104B for tank 4TA 1810B. Flow Metering device 4FT 18122 is provided for monitoring the Instantaneous raw diesel oil flow (4 -20mA) and Totalisation on HCS. 

The raw diesel oil shall be loaded at a maximum rate of 200 m³/h. Diesel oil bunkering station is provided with Audio Alarm( LK18101) and Visual Alarm ( LL18101) indicating that Raw diesel oil tanks are FULL and  requesting to STOP the raw DO supply vessel pumps.  Audio Alarm( LK 18101) and Visual Alarm( LL18101) are activated  when the raw DO storage tank Level High (LAH 18102A/B) set at 90% of the safe filling height for Operator Indication tank has filled at 90% height . Then the operator has to send the message to supply vessel through Walkie Talkie to stop the supply Vessel Pump. Tank  Level High High ( 4LSHH 18101A/B) set at 95% of the tank safe filling height  gives an Audio Alarm (LK 18101) and Visual Alarm (LL18101) and close the shutdown valve 4SDV 18113 automatically by PSS. The acknowledge push button for the Klaxon and the Flash light alarm is located outside near the Klaxon. 
Transferring diesel oil among storage tanks and diesel unload:
Raw diesel oil Transfer pumps 4GX 1840A/B allow to transfer the raw diesel oil from  TA 1810A   to  TA 1810B and  vice  versa.  These pumps are also allows raw DO to be back 
loaded from tanks 4TA 1810A/B  to  a  Supply  Vessel.  

Transferring the Diesel oil to the settling tank 
Raw diesel oil shall be transferred from Storage tanks TA1810A/B to Settling Tank TA 1850 through raw diesel oil Transfer pumps GX 1840A/B. The raw DO transfer pumps operates in 
duty  stand  by  mode  and  also  provides  Pressure  transmitters  in  the  pump  suction  (4PT18409A/B)  and discharge  (4PT  18406A/B)  connected  to  PSS.  If  pump discharge  pressure  is High High (4PSHH 18406A/B) and Suction Pressure is Low Low (4PSLL 18409A/B) trip the 
pumps. The Low Low trip alarm is inhibited during the start-up of the pump. Bypassing the Settling tank 4TA1850 (If required, during the maintenance): 
Transfer the raw diesel oil from raw diesel oil storage tank 4TA1810A/B to Purifier  Package (4UB 1880A/B/C/D/E) through Feed pumps (4GX1840A/B). The operation shall be as 
follows:          
  • CLOSE the manual operated Valve B- 18001 
  • 4" Normally Close manual operated valve installed on the Line 4"-DO-4-1848-B49H-
  • N Shall be OPEN 
  • SDV 18508, SDV 18504 shall be CLOSE by the operator on HCS 
  • Tank  Selection  4TA1810  A  or  B  and  the  respective  SDV18105A  or  SDV  18105B, 
  • OPEN by the operator on HCS  
  • Pump 4GX 1840A/B,  Start / Stop shall be done by the operator on HCS 

Diesel Oil Purification








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