Oily water separator in use on hydrocarbon tankfarm

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Oil-water separator for tank farm secures effluent in rain run-off.
The Hydro-Carbon Filtration & Separation oil-water separator, from the PPS series, is a passive system for the separation of oil and solids from waste water. It is a stationary unit which utilises gravity and the coalescing action of the plates for oil removal. The unit is provided with an additional oil adsorption step. The adsorption step, filled with environmental friendly wool based adsorption product, will remove mechanically emulsified oil and a part of the chemical emulsified oils. The wastewater flows into the inlet chamber of the separator where large solids and large oil droplets are separated from the water. The water, now containing only small amounts of solids and oil, enters the separator which is provided with coalescing plates and here the oil is separated and rises to the top. The oil then flows out through the adjustable “skimming” devices. After the larger part of the free, non emulsified oil is removed the water flows through the adsorption step to remove mechanical and some chemical emulsified oils. The clean processed water is discharged into the customers lines. Part of chemical stable emulsions as well as dissolved oil will not be separated with this equipment. The water coming from the oily water collecting system is gathered in the oily water sump. The oily water sump is provided with a level control unit that measures the level of oily water in the sump. Through a local ATEX control box the level control unit controls the oily water feed pumps delivered with the package. The package contains two pumps: one operating and one stand by. If the maximum level in the oily Water Sump is reached the level control will activate the selected feed pump. The pump will transport the oily water from the oily water sump to the inlet of the oily water separator. The oil-water mixture flows through the inlet distributing pipe into a primary settling chamber, the purpose of which is to separate the solids and larger oil particles.
The water, still containing the smaller oil particles, flows from the primary settling chamber to the coalescing plate separator. The coalescing plate separator contains sinusoidal, oleophilic shaped plates which are stacked at 6 mm spacing. The spacing, the total plate length and the liquid velocity ensure that at nominal flow, and depending on the actual density of the oil phase droplets of 30 microns and over will be separated. Due to the velocity by variations in the flow path, caused by the semi-sinusoidal flow path, oil particles of less than 30 microns are coalesced by generated particle collisions into oil particles larger than 30 microns which then are separated by gravity and are captured by the oleophilic plates. The oil collected on the plates is then allowed to weep to the surface through the plate pack, using the holes situated in the crests of the plates.
An oil-dam placed downstream of the plate packs prevents the separated oil from reaching the outlet-weir. The processed water flows underneath the oil-dam and leaves the compartment over the exit-weir. From here it enters a compartment provided with a wool-based adsorption material.
The adsorption material is treated to adsorb free, mechanically and some chemically emulsified oils from the wastewater. It will also function as an efficient filter for removing suspended solids and oil- particles. The oil flows out through the adjustable skimming device into the recovery oil pit. The recovery oil pit is provided with a level control system for the automatic control of the waste oil pump. The clean processed water is discharged into the drain lines.

Read more on oil-water separators / coalescing plate separators

Posted October 11, 2012

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