Liquefied gas carrier’s cargo handling system

Fully pressurized LPG carrier cargo handling system

The full-pressure LPG carrier cargo operating system is mainly used to load, transport and unload LPG at ambient temperature. The cargo is usually stored in a "C" type pressure tank made of carbon steel and with a design pressure of about 18 barG. The cargo tank(s) does not require insulation and due to the high design pressure the cargo can be transported without re-liquefaction equipment. LPG loading to tank is performed by the loading facilities of the shore based terminals and LPG unloading is done by the ship’s cargo pumps or cargo compressors.
 
cargo tank volume; From 2000m3 to 10000m3
Loadable cargo:
Propylene, propane, butane, propane/butane mixture, butadiene, vinyl chloride, butene isoprene, etc.
 
 

System composition

  • IMO "C" type pressure tank          
  • Cargo tank monitoring system
  • Loading and unloading system                
  • BOG handling system
  • Emergency shut down (ESD) system               
  • Cargo control system
     
 
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Semi-refrigerated gas carriers cargo handling system

The cargo handling system for a semi-refrigerated gas carrier is similar to the full pressure gas carrier: The system includes "C" type pressure tanks for storage of the cargo but is also equipped with a re-liquefaction unit to keep the cargo at low temperature. Due to the lower cargo temperature, the design pressure of the cargo tanks is lower than for fully pressurized tanks. The material of the bulkhead of the cargo compartment is usually low-temperature steel, which is suitable for carrying most liquefied petroleum gas and chemicals above -48°C. The cargo tank can also be made of low-temperature alloy steel or aluminum alloy material to transport ethylene at -104 °C. The cargo handling system of this type of vessel is generally flexible and can be loaded and/or unloaded to the pressure or refrigeration tanks on shore.
Loadable cargo:
Ethylene, ethane, anhydrous ammonia, liquefied petroleum gas, vinyl chloride, etc.
 

System composition

  • IMO "C" type pressure tank
  • Cargo tank monitoring system
  • Loading and unloading system
  • BOG handling system
  • LPG liquefaction system
  • LEG liquefaction system
  • Emergency shut down (ESD) system
  • Cargo control system

 
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LNG carrier cargo handling system

For small and medium-sized LNG carriers the cargo is generally stored in "C" type pressure tanks with thermal insulation such as polyurethan spray foam insulation. The cargo tanks are made of low-temperature resistant steel, suitable to carry low-temperature liquid natural gas at -163 ° C. Small and medium-sized LNG carriers are usually designed with alternative means for handling boiloff gas generated in the tank. Multi-purpose gas carriers, they can carry liquefied natural gas, and can carry ethylene, liquefied petroleum gas, vinyl chloride and other cargoes.
 
 

Boiloff gas is usually handled by following methods:
 

* Storage of evaporative gas under pressure in the tank
* Boiloff gas is burned
* Boiloff gas is used as fuel
* Boiloff gas is re-liquefied

System composition

* Cargo maintenance system
* Cargo tank monitoring system
* Loading and unloading system
* BOG handling system
* Emergency shut down (ESD) system
* Cabin capacity metering system
* Cargo control system

LNG bunkering vessel cargo handling system

The design of the LNG bunkering vessel cargo system should meet the international regulations for loading, transporting, and bunkering the liquefied natural gas with a minimum service temperature of -163°C. LNG loading to tank is performed by the loading facilities of the shore based terminals and bunkering/unloading is of liquefied natural gas is done by the ships cargo pumps.
 

The main functions are as follows:

* LNG cargo transportation
* LNG ship-to-ship refueling function
* LNG bunkering metering function
 
 

System composition

* Cargo maintenance system
* Cargo tank monitoring system
* Loading and unloading system
* BOG handling system
* LNG bunkering system
* Emergency shut down (ESD) system
* Cabin capacity metering system
* Cargo control system