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

Ballast Voyage HEEL Retention & Management

Maintain tank temperatures

LNG gas burning

Piping Arrangement Cargo tank dome –Type “C” Tank

ESD

HD Compressor Heater

Preparation to gas Free (Boil Off – LNG)

How do you know when the liquid has gone?

Boil Off

HD Compressor Heater

Cargo Heating System

Warm Up - LNG

HD Compressor Heater

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

Warm Up

HD Compressor Heater

Inerting to Remove Cargo Vapour

Inert Gas

Warm LNG Vapour

To Vent Mast or Boiler

IG

Inert Gas

LNG Vapour

Purging LNG

• To maintain a non flammable atmosphere

• To prevent contamination between cargoes

Inert Gas

To Vent mast

Air

Aeration

Clean Dry Tank without any washing

LNG Future

Source: ABS