Gas Carrier Vessels: Technicalities, Uses, and Advantages
As the name suggests, gas carrier vessels are ships that carry gas in different forms like LPG, CNG, LNG, etc. Each type of gas is carried by a different type of carrier vessel.
Gas Carrier Vessels Technical Details
Dimensions and Capacity
Gas carrier vessels have several types, and technical details vary from type to type. Following is an account of the dimensions of gas carrier vessels.
Fully pressurized ships
The first and simplest type of gas carrier vessel is the pressurized ship. They transport gas at normal environmental temperatures.
Carrying Capacity: These have a carrying capacity of 4000 to 6000 m3.
Pressure: Their type C pressurized tanks and can handle the pressure of 18-20 bar.
Semi-pressurised ships:
These types of ships offer both pressurization and refrigeration capabilities. It also uses type C tanks and, thus, does not require a second barrier.
Carrying Capacity: Semi-pressurized gas carrier vessels have a carrying capacity ranging from 3000m3 to 20000m3.
Temperature: They can be made to have a temperature of around -48° C, which is suitable for the transport of LPG and other chemical gas. Or they can be made to have a temperature of -104° C.
Pressure: These vessels can handle the pressure of around 7 bar, which is less than the pressure capacity of fully pressurized ships.
Ethylene ships
Ethylene ships are refrigerated, thermally insulated, and have high-grade liquefaction capabilities. They also use type C vessel tanks.
Carrying Capacity: Ethylene gas vessels usually have a capacity of 1000 to 12000 m3.
Temperature: Ethylene ships can have a temperature of around -104°C..
Fully refrigerated LPG ships
They use type A tanks with second barriers and are fitted with insulation and liquefaction capabilities.
Carrying Capacity: Their carrying capacities range from 20000 to 70000 m3.
Pressure: The maximum working pressure they can handle is around 0.7 bar.
Temperature: Fully refrigerated LPG ships are made of low-temperature steels that allow a temperature of around -48°.
Use: These types of gas carrier vessels are larger in size and are used for the transport of liquid petroleum gas(LPG) and other types of gas in large volumes.
LNG ships
LNG ships are larger gas carrier vessels that transport liquid natural gas.
Carrying Capacity: They have a capacity of 120000 to 135000 m3.
Temperature: LNG is carried at its boiling point, which is -162° C.
Uses: Carrying liquid natural gas in large volumes.
Engine Power and Performance
The average speed for gas carrier vessels is 14-19 knots per second. LNG ships can burn around 35.6 metric tons of fuel when moving at the speed of 16 knots.
Uses of Gas Carrier Vessels
Industrial Use
- Fully pressurized vessels carry LPG and ammonia, while semi-pressurized ones carry a whole lot of other chemical gasses like butadiene.
- Ethylene ships carry refrigerated ethylene gas that is used in the polymer and chemical industry.
Commercial Use
- Larger LPG and LNG vessels are used to carry large amounts of these gasses to be used in different parts of the world.
Advantages of Gas Carrier Vessels
- Gas carriers provide efficient transport of fuel in large quantities over longer distances.
- By liquefaction of the gas, they significantly reduce the volume that gas cargo takes up.
- LNGs use their boil-off gas as fuel which makes them more cost-effective and energy-efficient.
FAQs
Q: What are the classifications of gas carriers?
A: The gas carrier vessels are of the following types: fully pressure, semi-pressurized, ethylene carrier ships, fully refrigerated ships, and LNG ships.
Q: What is the difference between a tanker and a gas carrier?
A: Oil tankers carry cargo that's naturally in oil form, like petroleum or mineral oils. Gas vessels carry gaseous cargo by liquefying them.
Q: What are 1G, 2G, and 3G gas carriers?
A: This is a classification of LNG ships. 1G ships carry the most hazardous cargo, 2G carry lesser hazardous cargo, and 3G transport the least hazardous cargo.