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Megator Oil Water Separator Operational Theory

Parallel plate oil water separators are devices that permit the removal of oil from awaste stream by allowing the oil droplets to rise out of the hydraulic flow path ofthe separator and thereby extracting them from the waste flow. In theory, the flowthrough velocity (V) of a vessel is a function of the vessel size and flow rate(gpm). The velocity is then compared to the rate of rise of the oil droplet and thelength of the vessel. If the resulting calculated trajectory (T) of a given droplet willallow it to rise out of the effluent flow path before it reaches the vessels exit, it isremoved. This is an application of Stokes Law and terminal velocity to the rate ofrise of a particle in a liquid medium.

The separation process can be accomplished and enhanced in a variety of ways

and with a variety of equipment configurations. One common way to improveseparation without increasing the needfor floor space is to install a multiple platepack that will create many separationchambers in one vessel, each with ashallow depth. This is done by adding aseries of appropriately spaced plates.The flow is distributed through the platesand the rate of rise of the droplet isapplied to the application. Theadvantages of multiple plates is that surface areais increased without requiring additional floorspace.

The most efficient oil/water separators are designed to exploit Stokes Law andthe rate of rise for a given droplet. In order for a particle to be removed accordingto Stokes Law, the separator must conform to several critical design criteria suchas:

Laminar flow conditions must beachieved (Reynolds Re number less

than 500) in order to allow a droplet torise.

Hydraulic flow path must distributeinfluent AND effluent flow in such a wayas to ensure complete utilization of thecoalescing surface area in order to takefull advantage of the plate packcoalescing surface area. Design of theflow distribution must be such as to prevent anyhydraulic short circuiting of the plate pack, which would be detrimental.

Rate of Rise Theory

Parallel Plate Pack

MEGAT R Pump ing & Pol lu t ion Contro l Solut ions

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Horizontal flow-through velocities in the separator must not exceed 3 feet perminute or 15 times the rate of rise of the droplets - which ever is smaller, perthe American Petroleum Institutes Publication 421 of February 1990.

Coalescing surface area must not become clogged during use, which wouldadversely alter flow characteristics, possibly creating hydraulic short circuitingand increasing the Re number past 500.

If inclined parallel plates are used, they must be at the proper angle of reposeto allow solids to settle in a liquid medium (ideally 55-60 degrees fromhorizontal) , and they must be smooth enough to allow the unhinderedmigration of a solid particle to the bottom of the plate pack and an oil droplet tothe top of the plate pack where they will exit the waste stream.

There are several important factors to consider in efficient parallel-plate, oil waterseparator design. As stated earlier, the parallel plate must have a smoothsurface in order to allow unhindered migration of the droplet to the top of the packand solid particles to the bottom. Another enhancement is to use crosscorrugated plates. Corrugated plates provide additional coalescing surface area,within the same volume, in the form of crests and valleys, that aid in the migrationof the droplet to the top of the pack. As the droplets impinge on the crests andvalleys and begin to migrate toward the top of the plate pack, they will coalescewith other droplets, thus creating larger droplets with increased mass which willimprove their rate of rise.

Megator employs parallel plate oilwater separator in a most efficientmanner. We use ultra-smoothsurface, cross-corrugated plates, thatare arranged at a 60 degree angle ofinclination. This promotes self-flushing and efficient dropletagglomeration, which improves themigration of droplets toward the topof the plate pack and sludge to thebottom of the plate pack and out of

the waste stream into the sludgesettling chamber. Our influent andeffluent flow distribution systems are carefully designed to ensure efficient, evenand complete usage of the entire plate pack and to prevent short circuiting. Insummary, our parallel plate oil water separators are thoughtfully designed toensure reliability and performance. We also offer custom design services to meetspecific requirements.