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| Applications
- Industrial / Chemical Plants
MSR OIL WATER SEPARATORS FOR
CHEMICAL PLANTSMSR
Coalescing plate separators are one of the best ways to separate two non-mixing
liquids. Almost any hydrocarbon oil and most non-hydrocarbon oils such as corn,
orange, or other vegetable oils may be separated from water very satisfactorily.
The MSR separator is an enhanced gravity separation system for removing oil droplets
from water. The design utilizes the difference in specific gravities between the
oil and the water to perform the separation. MSR has many years experience in
designing systems for varying applications. Please contact MSR to discuss all
of your separation needs for process improvement or effluent control. 
Coalescing plate separators can be used to:
Separate
oil from wastewater as an industrial pretreatment system prior to directing the
water to sewer or other disposal.
Separate oil from circulating water or
other aqueous phase systems to remove the oils so that the stream can more economically
be reused or so that the oil in the water stream does not cause problems elsewhere
in the system by fouling heat exchangers or catalysts.
Separate oil from
water or water from oil so that either the oil or water or both may be purified
and reused or recycled. It is also possible to separate a mixed oil and water
stream to both remove the oil from water to low concentrations and remove the
water from the oil to low concentrations in a single system.
Industrial pretreatment
of waste streams prior to disposal to sanitary sewer systems:
When
the choice exists of either discharging wastewater effluent into a lake or stream,
or to the sanitary sewer, the best choice is often the sanitary sewer. This is
because the outlet oil concentration requirements are usually less stringent.
Sanitary sewer plant operators usually require that any plant wastewater streams
meet certain required characteristics - or be pretreated to meet those requirements.
The
requirements for pretreatment may in certain instances be very stringent, but
usually range from 50 mg/l of oil to about 150 mg/l. These treatment levels are
readily achieved by the use of MSR's technology.
Pretreatment
systems can be any size or configuration, but are generally relatively small in
chemical plants because plants try to minimize their waste streams. MSR Pretreatment
Systems are designed to handle either gravity or pumped flow on a single-pass
or re-circulating basis. The separator vessel is usually constructed of carbon
steel, provided with a special corrosion resistant coating both internally and
externally. Systems are also available in stainless steel, aluminum or corrosion
resistant plastic and may also be used in existing tanks or concrete pits. The
following is a case history of one pretreatment system MSR recently designed for
a chemical company in Texas: The
facility is a large surfactant (surface active agent) plant belonging to a major
international chemical company. The plant had a relatively simple oil interception
system consisting of a couple of small concrete lined pits with a skimming device
and underflow/overflow system. The
effluent hydrocarbon content was often over the requirements of the local sanitary
sewer authority and the sewer authorities were becoming impatient. MSR
reviewed the existing system and discussed the various aspects of the design with
local plant engineers and chemists. We determined that the presence of the surfactants
(everywhere in the plant and process) would cause the hydrocarbons to be present
as very small and therefore difficult to remove droplet sizes. After further consultation
with the plant personnel concerning other operating parameters, MSR designed a
special separator to meet the plant's needs using our coalescing plates molded
in polyoxymethylene plastic to meet the compatibility requirements of the service.
We also provided an integral oil holding tank with high and low level switches
and an oil discharge pump (vertical centrifugal type). The drawing below shows
the final design flow scheme.
Aqueous
phase with hydrocarbons enters the system from the main process through the inlet
nozzle into the preseparation chamber. This chamber is separated from the main
separator by an inlet baffle. Most of the entering aqueous phase flows under the
baffle and into the inlet chamber. The inlet baffle is provided with holes to
allow any free oil that enters with the inlet flow to pass across to the inlet
chamber where a high-capacity oil skimmer is located. This skimmer is adjustable
so that it will skim the captured oil off of the top of the aqueous phase to the
oil holding tank.
After
the inlet chamber, the water passes through the coalescing plates where most of
the small oil droplets are removed. The droplets are captured on the plates, coalesce
to form large drops, and the drops migrate upward to the surface of the separator.
Downstream of the coalescing plates a second skimmer helps remove the oil layer.
The
cleaned water then passes under the oil dam and exits the separator through an
adjustable water weir and clearwell. After the separator, the water is directed
to the sanitary sewer through the previously installed effluent system.
Hydrocarbons
captured in the system are skimmed to the oil tank and automatically pumped to
a separate oil holding tank.
The
photo below shows this unit during field assembly.
 OPERATING
RESULTS:
After
the system was installed and operations started, it was discovered that, in addition
to the light hydrocarbon the system was designed to capture, there was also some
hydrocarbon heavier than water present. It appears that the heavy hydrocarbon
may appear in the separator when a process upset happens upstream. The separator
successfully captured large quantities of this heavy hydrocarbon in addition to
the light hydrocarbon. A separate detection system was subsequently installed
to detect the presence of the heavy hydrocarbon so that it can be removed.
 While
it is extremely difficult to separate oil in the presence of surfactants, this
special design has operated very satisfactorily consistently producing water effluent
quality that meets the local sanitary sewer authority requirements. And - the
heavy hydrocarbon recovered is a salable product. The plant has recovered over
3000 gallons of product using this separator - a very profitable though unexpected
effect of installing the system. The chart below shows some of the analyses done
to prove the effectiveness of the system.
Plant
Process ImprovementThere
are dozens of places in any chemical plant where it is necessary to separate aqueous
and hydrocarbon streams. These have often been mixed intentionally to facilitate
a chemical reaction or may result from water phases condensing within the process.
Rain water may also enter the tops of storage tanks and migrate to the bottom
of the hydrocarbon phases.
MSR
Coalescing systems can be used almost anywhere there are two non-mixing phases
to be separated and can improve process operations and increase recovery of valuable
products. MSR designs have many advantages:
May
be installed in existing vessels, tanks, concrete pits or other housings.
Can be used in either atmospheric tanks or pressure vessels.
Possible
flow rates are almost unlimited. MSR engineers have designed systems up to 20,000
US gpm flow rates.
They have relatively wide spaced plates which do not
plug easily like coalescing cartridges.
No absorbents to be used up and
require disposal.
They are suitable for installation in systems where
some surface active agents such as soaps or detergents are present. Note: coalescing
plate separators are not suitable for all such systems and special designs are
necessary. Please consult MSR if you have a system of this type and would like
suggestions on design.
Unlike cartridge type coalescers, coalescing plate
separators can recover from large amounts of surfactants which would require replacement
of cartridge type coalescers.
Please
contact
MSR to discuss all of your separation needs for process improvement or effluent
control.
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