Energy Transport [Tankers]
- Tankers transport crude oil, petroleum products, and other liquid cargoes such as chemical products. These vessels feature a double-hull structure which is designed to prevent the leakage of liquid cargoes in case of an accident.
The largest type of tanker carries crude oil, which supports the global economy and our everyday lives. There are different types of crude oil tankers categorized by their size.
Crude oil tanker names by size
- Very Large Crude oil Carrier (VLCC): 200,000 — 320,000 DWT
- Suezmax tanker: 140,000 — 150,000 DWT
The largest ship type that can pass through the Suez Canal in laden
- Aframax tanker: 80,000 — 120,000 DWT
The cargo tanks on these vessels are normally separated into two or three blocks lengthwise and another several blocks crosswise, allowing the vessel to load different types of cargoes.
In general, the cargo is discharged from the tanker to an offshore terminal.
The basic hull structure and loading/discharging methods for product tankers and chemical tankers are the same as for crude oil tankers. However, some chemical/product tankers have more cargo tanks so they can load a wider variety of cargoes. Usually, each tank has its own pipelines and cargo pumps to prevent cross-contamination of different products.
Since these cargoes tend to be more corrosive than crude oil, tanks and pipelines require anti-corrosive measures. For example, corrosion-resistant materials such as stainless steel are employed for cargo tanks, and special coatings are applied inside tanks and pipelines.
Product tankers carry petroleum products such as gasoline, naphtha, kerosene, and diesel oil. These ships are essential in transporting cargo to areas that do not have facilities to refine crude oil. There are generally three classes of product/chemical tankers. These days, larger vessels are becoming more common as demand increases.
Product Tanker Names by Size
- MR type (Medium Range): 25,000 — 60,000 DWT
- LR I type (Large Range 1): 55,000 — 80,000 DWT
- LR II type (Large Range 2): 80,000 — 160,000 DWT
Chemical tankers transport liquefied chemical products such as benzene, toluene, and alcohol products
LPG tankers carry liquefied petroleum gas (LPG) such as propane and butane.
In addition to propane and butane, some LPG tankers can transport ammonia, which is used as a raw material for chemical fibers and fertilizers, and propylene, which is used as a raw material for petrochemical products. Very Large Gas Carriers (VLGCs) are employed mainly for long-distance transport of propane and butane. As the boiling points of liquefied propane and liquefied butane are minus 42.2°C and minus 0.5 °C respectively, the cargo tanks are made of a special steel that can withstand these ultra-low temperatures and the vessels feature a re-liquefaction system to keep the cargo temperature below the boiling point.
Another type of LPG tanker pressurizes cargoes to liquefy them. This method is used mainly on smaller vessels such as coastal ships.
Methanol carriers are chemical tankers designed especially to transport methanol, a raw material for formalin and a widely used fuel for alcohol lamps. In 2016, MOL added three innovative vessels to its fleet—newbuilding methanol carriers equipped with low-speed diesel engines that can run on either their methanol cargo or conventional heavy fuel oil.
Using methanol as a vessel fuel can reduce emissions of carbon dioxide (CO2) by 10% and nitrogen oxide (NOx) by 18% compared to engines powered by heavy fuel oil. It also significantly reduces emissions of sulfur oxide (SOx) and particulate matter (PM) because methanol contains no sulfur. The three vessels, which are recognized as advanced "eco ships" with full use of the latest telecommunications, Internet of Things (IoT) and artificial intelligence (AI) technology as well as environment-friendly fuel, won the "Technology Special Prize" in the "Ship of the Year 2016" awards.