Hydraulic tanker

Last updated
The tanker San Nazario Tanker San Nazario.jpg
The tanker San Nazario

A hydraulic tanker is an oil tanker designed to use water as an incompressible fluid for loading and unloading petroleum cargo. Each cargo tank is kept full at all times so oil floating on water will be pressed against the top of the tank. A cargo tank initially filled with water is loaded with the desired quantity of oil by pumping oil into the top of the tank displacing water which overflows through an opening at the bottom of the tank. The cargo tank is unloaded by removing oil from the top of the tank as water is admitted at the bottom.

Contents

Theory

Hydraulic tanker design bases: [1]

Advantages

Oil pumps located on an upper deck avoid dangerous volatile hydrocarbon accumulations in pump rooms near the bottom of a ship. Ship stability is improved by eliminating free surface in partially filled tanks. [2] Ship structural stresses are reduced by eliminating dynamic loading caused by sloshing of fluids in partially filled tanks. Avoiding exposure to atmospheric oxygen reduces corrosion within the tank, and reduces hardening of residual crude oil deposits remaining after unloading. [3]

Disadvantages

The hydraulic system is ineffective with heavy or viscous oils and not recommended for greater than 15-degree Baumé. [3] Heating coils must be placed near the top of tanks, where they are less efficient. [4] An hydraulic tanker requires a larger volume of void space for buoyancy than conventionally loaded tanks, because the empty, or ballasted, condition of tanks filled with water is heavier than the loaded condition of tanks filled with oil. A heavier ballasted condition may also increase round trip fuel consumption. [5]

Many petroleum compounds have limited solubility in water. Low solubility is typically of negligible concern with respect to product loss, but toxic petroleum products may be regarded as pollution in the water displaced as a tank is loaded with petroleum. The latter disadvantage may be insignificant where navigable waters contain elevated background levels of petroleum products; and the advantages make hydraulic tankers useful oil spill recovery ships when their storage tanks may act as oil–water separators. [6]

Notes

  1. Morrell (1931) p. 305
  2. Manning (1930) pp. 47–49
  3. 1 2 Morrell (1931) p. 306
  4. Morrell (1931) p. 337
  5. Morrell (1931) pp. 307–312
  6. Shoji, Uchida; Hiroshi, Takeshita; Yajuro, Seike. "Development of Oil Spill Recovery Ship". 1977 Oil Spill Conference. Retrieved 23 January 2017.

Sources

Related Research Articles

A double-hulled tanker refers to an oil tanker which has a double hull. They reduce the likelihood of leaks occurring compared to single-hulled tankers, and their ability to prevent or reduce oil spills led to double hulls being standardized for oil tankers and other types of ships including by the International Convention for the Prevention of Pollution from Ships or MARPOL Convention. After the Exxon Valdez oil spill disaster in Alaska in 1989, the US Government required all new oil tankers built for use between US ports to be equipped with a full double hull.

MT <i>Alma</i> Aframax crude oil tanker

MT Alma is an Aframax crude oil tanker. Formerly known as Mastera for almost two decades and briefly as Mikines in early 2022, she and her sister ship Tempera were the first ships to utilize the double acting tanker (DAT) concept in which the vessel is designed to travel ahead in open water and astern in severe ice conditions. The icebreaking tanker was built to transport crude oil year-round from the Russian oil terminal in Primorsk to Neste Oil refineries in Porvoo and Naantali.

<i>La Noumbi</i> Floating production storage and offloading unit operated by Perenco

La Noumbi is a floating production storage and offloading (FPSO) unit operated by Perenco. The vessel, converted from the former Finnish Aframax crude oil tanker Tempera by Keppel Corporation, will replace an older FPSO unit in the Yombo field off the Republic of Congo in 2018.

Crude oil washing (COW) is washing out the residue from the oil tanker using the crude oil cargo itself, after the cargo tanks have been emptied. Crude oil is pumped back and preheated in the slop tanks, then sprayed back via high pressure nozzles in the cargo tanks onto the walls of the tank. Due to the sticky nature of the crude oil, the oil clings to the tank walls, and such oil adds to the cargo 'remaining on board'. By COWing the tanks, the amount of ROB is significantly reduced, and with the current high cost of oil, the financial savings are significant, both for the Charterer and the Shipowner. If the cargo ROB is deemed as 'liquid and pumpable' then the charterers can claim from the owner for any cargo loss for normally between 0.3% up to 0.5%. It replaced the load on top and seawater washing systems, both of which involved discharging oil-contaminated water into the sea. MARPOL 73/78 made this mandatory equipment for oil tankers of 20,000 tons or greater deadweight.

Ballast is used in ships to provide moment to resist the lateral forces on the hull. Insufficiently ballasted boats tend to tip or heel excessively in high winds. Too much heel may result in the vessel capsizing. If a sailing vessel needs to voyage without cargo, then ballast of little or no value will be loaded to keep the vessel upright. Some or all of this ballast will then be discarded when cargo is loaded.

A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard, typically by a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks.

Chemical tanker

A chemical tanker is a type of tanker ship designed to transport chemicals in bulk. As defined in MARPOL Annex II, chemical tanker means a ship constructed or adapted for carrying in bulk any liquid product listed in chapter 17 of the International Bulk Chemical Code. As well as industrial chemicals and clean petroleum products, such ships also often carry other types of sensitive cargo which require a high standard of tank cleaning, such as palm oil, vegetable oils, tallow, caustic soda, and methanol.

Tanker (ship) Ship designed to transport liquids or gases in bulk

A tanker is a ship designed to transport or store liquids or gases in bulk. Major types of tankship include the oil tanker, the chemical tanker, and gas carrier. Tankers also carry commodities such as vegetable oils, molasses and wine. In the United States Navy and Military Sealift Command, a tanker used to refuel other ships is called an oiler but many other navies use the terms tanker and replenishment tanker. Tankers were first developed in the late 19th century as iron and steel hulls and pumping systems were developed. As of 2005, there were just over 4,000 tankers and supertankers 10,000 LT DWT or greater operating worldwide.

Oil terminal Industrial facility for the storage of oil, petroleum and petrochemical products

An oil terminal is an industrial facility for the storage of oil, petroleum and petrochemical products, and from which these products are transported to end users or other storage facilities. An oil terminal typically has a variety of above or below ground tankage; facilities for inter-tank transfer; pumping facilities; loading gantries for filling road tankers or barges; ship loading/unloading equipment at marine terminals; and pipeline connections.

Free surface effect Effect of liquids in slack tanks

The free surface effect is a mechanism which can cause a watercraft to become unstable and capsize.

Storage tank Container for liquids or compressed gas

Storage tanks are containers that hold liquids, compressed gases or mediums used for the short- or long-term storage of heat or cold. The term can be used for reservoirs, and for manufactured containers. The usage of the word tank for reservoirs is uncommon in American English but is moderately common in British English. In other countries, the term tends to refer only to artificial containers.

The Stability conditions of watercraft are the various standard loading configurations to which a ship, boat, or offshore platform may be subjected. They are recognized by classification societies such as Det Norske Veritas, Lloyd's Register and American Bureau of Shipping (ABS). Classification societies follow rules and guidelines laid down by International Convention for the Safety of Life at Sea (SOLAS) conventions, the International Maritime Organization and laws of the country under which the vessel is flagged, such as the Code of Federal Regulations.

LNG carrier

An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG).

Oil tanker Ship that carries oil

An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries. Product tankers, generally much smaller, are designed to move refined products from refineries to points near consuming markets.

Oil tankers generally have from 8 to 12 tanks. Each tank is split into two or three independent compartments by fore-and-aft bulkheads. The tanks are numbered with tank one being the forwardmost. Individual compartments are referred to by the tank number and the athwartships position, such as "one port", "three starboard", or "six center."

Cargo control room

The cargo control room, CCR, or cargo office of a tankship is where the person in charge (PIC) can monitor and control the loading and unloading of the ship's liquid cargo. Prevalent on automated vessels, the CCR may be in its own room, or located on the ship's bridge. Among other things, the equipment in the CCR may allow the person in charge to control cargo and stripping pumps, control and monitor valve positions, and monitor cargo tank liquid levels.

Liquefied natural gas terminal

A liquefied natural gas terminal is a facility for managing the import and/or export of liquefied natural gas (LNG). It comprises equipment for loading and unloading of LNG cargo to/from ocean-going tankers, for transfer across the site, liquefication, re-gasification, processing, storage, pumping, compression, and metering of LNG. LNG as a liquid is the most efficient way to transport natural gas over long distances, usually by sea.

Silverlip was a steam tanker built in 1902 by the W.G. Armstrong, Whitworth & Company of Walker for Sir Marcus Samuel owner and chairman of Shell Transport & Trading Company of London. The ship was designed and built to carry liquid cargo and spent her career carrying petroleum products from Borneo and Texas to United Kingdom and Europe.

Lucifer was a steam tanker built in 1899 by the C.S. Swan & Hunter Co of Wallsend for C.T. Bowring & Co of Liverpool. The ship was designed and built to carry oil and petroleum cargo in bulk and spent most of her career trading on routes from Philadelphia, Batoum and Novorossiysk to Hamburg and British ports.

Mielero was a steam tank ship built in 1916–1917 by Fore River Shipbuilding Company of Quincy for the Cuba Distilling Company of New York. The vessel was extensively employed on East Coast to Cuba route during her career and foundered on one of her regular trips in January 1920 with the loss of twenty two men.