Installation, operating and maintenance manual SKIT/S-DEB
3rd print version
page 45
9 – Process description
RWO GmbH
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Marine Water Technology
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Bremen
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Germany
Issue 2014-04-10
9
Process description
The RWO bilge water oil separator type SKIT/S DEB
meets the requirements of the latest IMO Resolution
MEPC. 107(49). The function mainly bases on the
principle of the open-pose coalescer which has already
been used successfully in the oil separator system SKIT/S
and is proven and tested. In a second stage, system
breaks up the emulsion and removes the oil from the
emulsion.
9.1
Oil water separation
An eccentric spiral pump (pos. 14) sucks through the SKIT
S-DEB from the bilge. This flow conduction avoids
unnecessary additional mixing of oil and water due to
pump turbulences upstream of the gravity oil separator. In
the 1st stage of the SKIT S-DEB the rough separation is
improved by using the different density of water and oil. A
very open porous coalescer causes, due to its extremely
oleophile surface, fine separation of even the smallest oil
drops. This system ensures the excellent efficiency of the
SKIT S-DEB oil separator.
9.2
Adsorber bypass
The adsorber bypass is controlled by the bilge alarm
monitor OMD (see P&ID).
The adsorber elements remove all types of carbon
hydrides from the water. The adsorption capacity is mainly
limited by the amount of dissolved or emulsified carbon
hydrides in the water, but dirt particles in larger amounts
can also block the adsorber. In order to extend the
adsorber lifespan, heavy emulsions with a high oil
concentration should be avoided by using rapidly
separating cleaning agents in the machine room.
Emulsions by air conditioning system or cleaning sludge
should not be discharged into the bilge water.
To increase the lifespan of the adsorber cartridges, an
automatic adsorber bypass is installed. The 15ppm
(5ppm) oil alarm monitor checks the water quality
periodically (every 5 minutes for 4 seconds) at the outlet of
the first oil separator stage. If the value at this measuring
point is below 14ppm (4ppm), the bypass valve (pos. 58)
guides the cleaned water directly outboard, passing the
adsorber stage. If the value is over 14ppm (4ppm), the
adsorber stage is activated. This process control ensures
a significantly increased useful life of the adsorber
cartridges.
During the short measurement time (4 seconds), the
3-way valve (pos. 23) guides the cleaned water back to
the bilge / bilge tank for safety reasons. This type of
control ensures that only cleaned water with less than
15ppm (5ppm) residual oil content can get outboards. By
factory default, the alarm threshold 2 is set to 15ppm
