Post on 07-May-2023
Start Discharge with Submerged PumpTank Isolating (Branch) Valve
Filling ValveDischarge Valve
Slowly Open – 12%? Fully Open
Check Full Shut
Adjust for Motor Load Slowly Close
Slowly Open
Post Discharge Operation• Draining tanks and pipelines
• Pump discharge valve should not be throtteled forflow control if the pump is operating with abooster pump (can damage pump)
• Cargo must be drained from all deck lines andcargo hoses or hard arms – by compressor (fromship to shore) or by blowing the liquid into ship’stanks using nitrogen injected at the base or apexof the hard arm.
• Only after depressuring all deck lines and purgingwith nitrogen ship/shore connection can beremoved.
liquid vapour
CONDENSATE RETURN LINE
VENT HEADER
INERT GAS HEADER
LIQUID HEADER
Reliquefaction
VapourCompressor
L.P.G.Vaporizer
Inert Gas Generator
L.P.G.Heater
Air Blower
VAPOUR HEADER
Aeration of tank
Aeration of Tanks
Ballast voyage
• Small quantity of cargo retain on bord (heel)• only if the same grade of cargo will be loaded
• For large LNG carriers 2000 to 3000 m3 may be retained in the tanks – fitted with spray cool-down pumps in each cargo tank to minimise tank thermal gradients
• On LPG-s small amount of liquid remaining to provide necessary cooling during ballast voyage – by using reliquefaction plant
HD Compressor Heater
Preparation to gas Free (Boil Off – LNG)
How do you know when the liquid has gone?
HD Compressor Heater
Warm Up LNG
Warm tank to what temperature?
Where do you measure the temperature?
Must be warmer than dew point of IG to prevent condensation in the tank
Inert Gas
LNG Vapour
Purging LNG
• To maintain a non flammable atmosphere
• To prevent contamination between cargoes