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What is an Oil Skimmer?

Oil floating on water.
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  • Written By: Mary McMahon
  • Edited By: Bronwyn Harris
  • Last Modified Date: 21 July 2014
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An oil skimmer is a piece of equipment which is designed to clean up spilled oil. There are a number of applications for oil skimmers, and there are a number of different styles on the market to meet various needs. These devices are used to clean up after tanker spills, to clarify mixtures of oil, water and other substances for commercial use, and to clean up various pumps and tanks in facilities which handle oil and other substances.

Oil skimmers fall into two basic categories. One type of oil skimmer is intended to remove oil in a usable state, while the other removes oil along with assorted other impurities. Oil skimmers pop up in some surprising places; many restaurants, for example, have oil skimmers in their grease traps to prevent oil and grease from clogging their drains. The use of oil skimmers is also an important aspect of environmental cleanup.

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There are a number of different ways in which an oil skimmer can work. Some rely on the simple operation of gravity, allowing oil to float to the top of the oil skimmer and then pushing the oil into a storage container. Other oil skimmers use belts, wheels, or rotating drums which are coated in substances which attract oil to pull oil from a contaminated fluid. Some fluids can be run through a centrifuge, which will pull the oil out of the liquid, while others are coalesced by being passed through a substance which will coagulate the oil and pull it out.

When quick containment is needed, some companies set up weir skimmers. These oil skimmers are floated on the water around the spill, and they allow water to flow through, but not oil. In these instances, the weirs serve two functions: they contain the spill, and they get a head start on cleanup. Cleanup personnel can also use hand held oil skimmers which essentially vacuum up the oil, while others deposit sponges or other absorbent materials into the spill to collect the oil so that it can be removed.

Oil skimmers come in various sizes, ranging from industrial oil skimmers which are designed to handle a high volume of contaminated material to smaller skimmers which are used by hand or on small spills. The sooner an oil skimmer is applied to an oil spill, the more successful it will be, as oil tends to spread into a slick, a very thin layer of oil which floats on top of water and other carrier fluids. Slicks are difficult to clean up since they are so thin, but they can deal a lot of damage.

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Discuss this Article

anon92005
Post 4

A serious question lies here with the Gulf spill, and that is, why were the 10-12(?) nations who offered to aid in this cleanup, shortly after it took place, by sending massive skimmer ships, turned down? When, in fact, those skimmers could have dramatically reduced, and continued to keep this slick from growing to the size it has, someone in charge has a lot of explaining to do. To refuse or deny this aid from other countries is unconscionable!

Fiorite
Post 3

@ parmnparsley - As far as cleaning up the oil that hits the shore and wetlands, there are very few good options. Skimming techniques that work close to shore will not be effective at cleaning the oil off of everything that it touches. They can only separate the oil from the water.

Some of the skimming techniques being used are absorbent skimming pads, drum skimmers, and sump vacuums. Probably the most effective for oil that is at the coastline are drum skimmers. They work by having a floating drum rotate in the water. This slowly rotating drum has oil stick to it, which is then wiped off by a squeegee the length of the drum.

The oil that is wiped off the drum is collected in a tray where it is sucked up by a sump pump. The oil is then put into containment equipment and transported to be processed or disposed of. These drums can operate in very low water levels, are fairly maneuverable, and they do not suck up much water.

As for getting the oil off of the marshland grasses, there are really two viable options, and neither is very good. One is to fertilize the water with the hopes that the natural microbes that digest petroleum can multiply and eat the oil. The other is to perform controlled burns in the wetlands. Both techniques have the potential to harm the ecosystem, but they are the lesser evils.

Technology for dealing with oil spills in ecologically important zones is still primitive at best, so we will have to wait and see if the cleanup efforts will work. The Exxon Valdez spill happened in 1989, and oil still occasionally washes ashore. The BP spill is already ten times the size of Exxon Valdez, and the gulf coast is more ecologically fragile.

Glasshouse
Post 2

@ parmnparsley - I agree that the spill is ridiculous, and that 100 skimmers are not enough to contain a meaningful portion of this spill. I read an article in the Augusta Gazette that outlined the skimming and boom laying operation by one of the contractors hired by BP. The individual contractors working on the clean-up are trying their best, but there aren’t nearly enough contractors to prevent potentially irreversible damage to the gulf ecosystem.

Basically, skimmers that are used in deep water can only pick up a total of 90,000 gallons of fluid on their boat, and once oil is separated from the water, they can haul 60,000 gallons of crude back to shore. These skimmers only pick up 10%-30% oil concentration in each pass. The rest is water that has to be processed out on the ship.

The company also stated that since the oil is so spread out, they are only getting about 10% oil concentration with their oil skimmers right now. This company has 9 skimmers that have all been deployed, so this should give you a good idea of how much oil open sea skimmers can pick up.

When you think about 60,000 gallons, it seems like a lot, but in the context of a spill that has already dumped 113 million gallons as of day 58, this amount barely measures. By the way, according to US government estimates, this spill has become the third biggest spill in world history. Even if you use the most conservative estimates, this is still the ninth largest oil spill in world history and it is hard charging up the rankings.

parmnparsley
Post 1

The oil spill in the gulf is one of the saddest things in the news this decade. I read an article about oil skimming equipment being used to clean up the spill, but It did not go into detail about what kind of skimmers were being used, and how much oil they could pick up. Does anybody know what type of skimmers they are using in the gulf, and how much oil they can expect to clean up with these? How does BP expect to clean up oil in the areas around the coast? It certainly doesn’t seem like the skimmers they are using will be able to clean oil that is pushed into mangrove forests and marshland grasses.

The article stated that there were only about 100 skimmers working the spill, but the spill was already the size of New York and New Jersey. It seems like only deploying 100 skimmers is more of a PR stunt than an effort by BP to actually clean any oil up. That's like only having 100 police officers peppered throughout New York and New Jersey, and trying to keep crime under control.

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