THE API SERIES OIL WATER SEPARATORS/وحدات الايه بى اى لفصل الزيوت عن المياه

The API Series oil water separators design guidelines.

GENERAL.DR

BAHAA BADR

TECHNOLAB EL-BAHAA GROUP

API Series
steel oil/water separators are a gravity
differential separation device for removal of
free and finely dispersed oil droplets
from oily wastestreams.

The design follows
the American Petroleum Institute’s (API)
#421 Design & Operation of Oil/Water
Separators Manual, February 1990.

API performance: 100mg/L, 150-micron
free, dispersed and non-emulsified oil
droplets.

The typical use of the API separator is to
reduce inlet loads of oil and suspended
solids in refinery wastewater.

Following the
API further treatment may be required, i.e.
coalescing oil water separator as a
polishing step and treatment of dissolved
organic materials with biological treatment,
and/or other treatment technologies (DAF
etc.).

The API steel design is just one of 8
different oil/water separator designs can be
used singularly or in combination with other
treatment processes such as emulsion
cracking, DAF & clarifier pretreatment.

The API can be installed above, flush with
or below grade.

Conversion to a DAF can
also be accomplished for flotation where
needed.

Features:

♦ A-36 carbon steel
♦ Adjustable water weir
♦ Integral oil reservoir
♦ Influent diffuser
♦ Expandable effluent chamber
♦ Sealed/gasketed covers
♦ Internal/external epoxy coatings
♦ Lifting lugs
♦ Flat Bottom
♦ Skid mounted
♦ Multi-section cover
Typical applications:
♦Groundwater remediation
♦Mobile separation system
♦ DAF/Clarifier pretreatment
♦ Power plant water treatment
♦ Refinery process water
♦ Aircraft wash racks
♦ Machining coolant oil removal
♦ Tank farm tank bottoms
♦ Vehicle washwater treatment
♦ R.O. Filter pre-treatment
♦ Oil spill recovery
♦ Trench water treatment
♦ Bilge water treatment
♦ Hydraulic fluid tank de-watering

Gravity Separation

The API separator separates via gravity and the
density differential of liquids per Stokes Law,
which defines the rise rate of an oil droplet based
on its density and size.

Typically, the difference
between the specific gravity of the oil and water is
much closer than the specific gravity of the
suspended solids and water.

Therefore, the
design of the API separator is based on the
difference in the specific gravity of the oil to be
separated and the wastewater.

Using this criteria
results in most suspended solids settling in the
API.

API effluent is then treated further in most
refinery wastewater treatment plants.

Per API guidelines design criteria are:

Depth to width ratio:

A minimum depth to width ratio
of 0.3 to 0.5 is specified so that separator does not
increase droplet rise time to reach the water surface.
Length to width ratio:

A minimum length to width
ratio of 5:1 is specified for API separators to keep flow
characteristics homogeneous, reducing short circuiting
effects.

Maximum channel width and depth:

The
maximum API separator channel width is 20 ft;
maximum depth is 8 ft.

Horizontal velocity: Maintaining a horizontal velocity
of no more than 3.0 ft/sec to minimize turbulence and its
interference with the separation process.

Influent distributor:

Minimization of high influent
velocity into the API separator, and possible short
circuiting associated with these high velocities, a diffuser
directs flow across the width and depth of the inlet
chamber.

Oil droplet size: Most oil droplets in refinery
wastewaters are 150 micron or larger.

The API design
standards were based on this droplet.

Droplets smaller
than 150 micron typically escape API separators and
further treatment processes, unless allowances are
made in the sizing of the

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THE API SERIES OIL WATER SEPARATORS/وحدات الايه بى اى لفصل الزيوت عن المياه O110

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