Mineral oils: processes and products – By treatment of solid mineral – e.g. – coal liquefaction – etc. – Specified procedure to improve separation of solids from...
Patent
1996-05-31
1999-03-09
Myers, Helane
Mineral oils: processes and products
By treatment of solid mineral, e.g., coal liquefaction, etc.
Specified procedure to improve separation of solids from...
206424, 202175, 159DIG3, 159 272, 196 23, 422261, 134 2218, C10G 100
Patent
active
058795413
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The production fluid from an oil well includes varying proportions of oil, water and gas in which are entrained solid particles, hereinafter referred to as "sand". This mixture is normally fed to a phase separator in which settling under gravity occurs into an upper gaseous layer, a middle oil layer, and an lower water layer. These are removed through separate outlets from the separator. The sand naturally settles out in the bottom of the water layer in the tank and it will be undesirable to allow this to be discharged through the water outlet, not least because the sand particles will be coated with oil and it is unacceptable to discharge such coated particles with the water back into the environment. Consequently the coated sand particles are recovered from the bottom of the phase separator and, according to one method, supplied to a vessel fitted with impellers which rotate in opposite directions to suspend the contaminated particles in water, causing dynamic contact of the particles, which mechanically strips away the oil coatings from the solid particles. The clean solid particles may then be discharged to the environment but the carrier water has to be treated, normally by flotation, to remove the oil. This is difficult, costly, and takes space which is at a premium on, for example, a marine platform.
Other situations obtain where it is necessary to clean oil-coated sand particles, for example when an oil spillage contaminates a beach.
SUMMARY OF THE INVENTION
According to the present invention, a method for separating oil from particles coated with oil comprises loading the coated particles into a housing containing a fluidising unit which has a liquid supply duct with an outlet and arranged to be fed with water under pressure from outside the housing, and a discharge duct within the liquid supply duct having at its end an inlet projecting beyond the outlet of the liquid supply duct, the discharge duct leading to a separator; feeding water to the liquid supply duct and causing it to swirl at the outlet such that it disturbs the oil and sand particles to cause the oil to be stripped, at least partially, from the particles, and causes the oil and sand particles entrained in the water to travel into the discharge duct and hence to a separator, where the oil, water and solid particles undergo separation.
The fluidising unit creates a swirling vortex which violently strips oil from the sand particles and also discharges the oil, water and sand without the need for any moving parts in contact with the separated components.
Although the method may be used for example, for cleaning sand from a contaminated beach after an oil spill, or for cleaning drilling mud, so that the mud is clean enough to be dumped, it is particularly useful for treating the oil-coated sand sedimented in a three phase separator for separating the components of the production fluid from an oil well. Alternatively, the contaminated sand in the production fluid may be treated by the method after settlement of the contaminated sand from the production fluid prior to its entry into the three phase separator. In these cases, the water fed to the liquid supply duct of the fluidising unit is preferably taken from the water outlet of the phase separator. This has the advantage that the water will still be at a comparatively high temperature, which will promote the stripping of the oil coating from the sand particles.
The separator may include a centrifuge or a single hydrocyclone stage which is arranged such that the oil is substantially separated and reports to the overflow and the water and sand report to the underflow. However, to improve the separation, two hydrocyclone stages are preferably provided, the first of which is a liquid/solid separation hydrocyclone, which substantially separates sand, which reports to the underflow from oil and water which report to the overflow, and the second of which is a liquid/liquid separation hydrocyclone, which substantially separates water which reports to the underflo
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Merpro Tortek Limited
Myers Helane
LandOfFree
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