Oil Mist Eliminator (OME) for Diesel Engines -Function & System Description

Oil mist eliminator(OME) of a diesel engine used to separate lubrication oil from oil mist produce in the crankcase. OME connected with crankcase venting pipe. In internal combustion engines,specially diesel engine running with heavy fuel oil some combustion gases always enter between the piston rings and the sleeve in the crankcase (called the blow-by). Without venting, these combustion gases will cause an unacceptable pressure increase in the crankcase.

Oil mist eliminator
Oil mist eliminator

The oil mist eliminator is driven by a fan. The attached electronic PID controller – with a pressure transmitter and frequency converter – maintains the exact negative pressure desired in the crankcase, even under variable operating conditions. Oil mist eliminators have a low pressure drop of 3-5 mbar to ensure reliable operation of the regulation and in order to avoid an inadmissible pressure increase in the crankcase.

System Description

The oil mist eliminator usually driven by motor powers a fan which sucks air charged with oil particles through the suction line attached to the air intake from the discharge of the crankcase of the internal combustion engine.

The air charged with oil particles flows first through the coalescence filter and then through the fine filter.

In the coalescence filter the fine aerosol droplets agglomerate to larger drops (due to the so-called coalescence effect), until they flow downwards by gravity.

Oil mist eliminator system description
Oil mist eliminator system description

In the fine filter the remaining small oil and dirt particles (0.1–80 μm) are separated. Diffusion, inertia and blocking effects superimpose themselves.

The separated oil flows through oil discharge lines downstream after each filter stage back into the engine oil sump. In the case of the optional double siphon both oil discharges are connected to the double siphon directly downstream from the device and a line needs only to be fed from the discharge to the crankcase. The double siphon filled with oil prevents the direct connection of the two oil discharges.

The air cleaned in this way is blown off through the fan air outlet . The oil remaining in the blown off air is max. 5 mg/m³.

An air blow-off line can be connected to the air outlet of the fan.

It should be taken into account that excess line pressure losses can reduce the max. feed rate of the fan. The combined max. admissible line pressure loss (suction and air outlet line) is 400 Pa (4 mbar).

The multi-stage oil separation of our oil mist eliminators guarantees a high separation efficiency of 99.97% at 0.3 µm and, even more importantly, a low residual oil quantity of < 5 mg/m³ after the filter, thus falling well below the legal limit values specified by TA Luft (Clean Air Guidelines).

Components Description

Coalescence filter (1): This filter (internal element) comprises a special fiber mix. Inside the filter housing the aspirated air is led through numerous high-efficient micro fiber cartridges. There the fine oil particles join to larger droplets within the micro fiber and flow downstream by gravity. 

Fine filter(2): This filter (outer element) is made of polyester material.

Oil mist eliminator components-cross section view
Oil mist eliminator components-cross section view

Fan(3): A radial fan is flange-mounted to the side of the device housing.

Electric motor of the fan(4): A three-phase asynchronous motor is flange-mounted to the fan.

Pressure gauges and transmitter(5): Two mechanical differential pressure gauges are fitted in the basic model. Electronic pressure transmitter Instead of analogue pressure displays. The pressure is displayed on the transmitter display.

oil mist eliminator components
Oil mist eliminator components

Mechanical shut-off valve intake(6): The shut-off valve is used to adjust the required under pressure in the crankcase for the internal combustion engine.

– Without the bypass option the valve may only be closed fully when the combustion engine is switched off. Non-compliance can cause damage to the combustion engine due to excess pressure in the crankcase.

– The valve may never be closed fully when the fan is running. If the valve is closed and the fan is running, oil or heavily oil-contaminated air is sucked through the oil discharges or the double siphon and is blown off unfiltered.

Bypass with mechanical shut-off valve (7): With this option maintenance and repair work can be carried out while the internal combustion engine is still running if necessary.

Oil mist eliminator components
Oil mist eliminator components

Oil discharges(8): Oil discharges are incorporated into the housing base downstream from the coalescence and fine filters.

Double siphon for oil discharge (9): Two sight glasses are attached to the double siphon for the visual inspection of the fill level.

Electronic under pressure control (10): The underpressure at the air intake is controlled with the pressure transmitter (5a) and the frequency converter FU1. The control system is provided with an actual value signal for an analysis via the splitter AS1.

Differential pressure transmitter
Differential pressure transmitter

Purpose & Benefits

For both power plant and marine-based engine applications, excessive pressure in the crankcase diminishes performance, causes oil leaks, and pushes harmful emissions to your surrounding environment. Vacuum-Assisted Oil Mist Eliminators are engineered to capture vented crankcase emissions and maintain crankcase pressure levels in accordance with the engine manufacturer’s specifications. These eliminators reduce the potential for oil leaks caused by excess pressure and eliminate harmful oil mist from engine rooms for improved health and safety. Since blow-by increases with engine wear, these systems incorporate manual, automatic, and recirculating devices to effectively control crankcase pressure over the engine’s entire life span.

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