Slop oil usually consists of complex emulsions of oil and water, along with substantial quantities of abrasive solids and other particles that derived from a wide variety of sources in refineries or oil fields.
They come from drainages, residues and cleaning processes, especially cleaning oil tank bottoms. Most of these slop oils contain a high percentage of oil which can be mixed with crude oil to be processed in the refinery. It can have very different compositions. The oil content, just like the proportion of water, can fluctuate from 10 to 90 percent. The proportion of solids can also vary from one to ten percent, depending on source.
Refineries around the world produce nearly ten million barrels of unusable oil each year. Add to that the annual worldwide well production of “Tank Bottoms/Sludge” which is a by product of its fields. Tank bottoms may also accumulate in tanks used for storage of fuels such as gasoline, fuel oil or diesel and jet fuel. There is no tank in the world without bottoms. This environmental problems associated present a severe costly disposal and treatment problem.
If this slop oil is treated, not only disposal costs can be reduced but profit can also
be generated with it phase recovered from the slop. As the oil as well as water
content can vary from 10 to 90 percent and the solid content can vary from 1 to 10 percent either disk stack centrifuges or decanters can be used for the treatment of it.
Traditional methods use costly chemicals to treat this problem. Most oil goes untreated and is disposed of in waste pits scattered around the world. Some of these waste pits are extremely large and can exceed 250,000 barrels. Waste pits are known to contaminate local groundwater and cause unwanted health problems if found to contain Arsenic, Barium, Cadium, Chromium, Lead, Selenium and Benzene. All attempts to treat these tank bottoms use either chemical or thermal treatments resulting in a more unwanted water solid mixture left behind. This “Dead Oil” presents an even more difficult challenge.
The first requirement of a profitable slop oil recovery system is the speed and efficiently that it can separate the three phases. The second is that it is works well enough to sever the closely bound emulsion and separate the smallest particles. Slop-oil or waste oil must go through purification in order to be used as fuel in waste oil fired boilers or incinerators, or be sold to refineries. Purification is carried out in several steps involving the removal of solids and water.