Breathe easy: The importance of emission reduction and energy efficiency


Courtesy of contec GmbH Industrieausrüstungen

Breathe easy

Blue oil mist is an unwelcome by-product of industrial work in the energy sector. contec specialises in high-powered, energy efficient and environmentally friendly oil mist filtration systems that reduce health risks and are an inexpensive alternative to traditional exhaust piping.

The high concentrations of blue oil mist produced by industrial production can result in health risks and environmental pollution. This applies particularly to large workshops and factories in which rotating machines such as wheel mechanisms, gas and steam turbines, turbo units or compressors for producing energy or compressed air are used.

The importance of emission reduction and energy efficiency has prompted the government to stipulate maximum pollution levels for these plants. With contec oil mist separators (COMS) these levels can be reliably maintained and high-quality lubrication oil is continuously regained. The separators fulfil all statutory requirements and the air quality produced is far higher than minimum levels stipulated by German TA clean air standards.

High-powered filters with glass fibre fleece elements have proven their worth when it comes to separating oil mist from the exhaust air produced by rotating machines. The requirement for truly clean air, however, is that the system pressure present or the excess pressure produced by the machine itself must be sufficient to overcome the pressure loss of the filter.

This is not the case with many machines, particularly in certain individual applications or under unfavourable operating conditions. For this reason exhaust air with a high concentration of oil is sometimes still discharged into the atmosphere through the roof of factories or workshops using complex, expensive pipe systems – shifting the problem, but not solving it.

The contec solution

The solution is a blower that extracts air containing oil mist and discharges it through the filter. This blower should always be installed on the clean side, i.e. behind the filter. This will help to prevent a malfunctioning of the filtration system.

Side-channel blowers have proven to be very successful in this case. They work reliably, have an optimal flow/pressure ratio and are relatively inexpensive. The appropriate filter elements have been designed specifically for this application. The exhaust air filtered in this manner is completely dry and clean from a technical point of view. It can remain inside the plant without any risk whatsoever, making complex, expensive exhaust pipe systems a thing of the past.

contec's filters are 99.98% effective at a droplet size of 0.1μ, residual oil content below 0.1 mg/m³ and no particles between 0.2 µm and 0.9 µm in clean gas. This means that the air is far cleaner than that required by German TA clean air standards. The COMS were awarded the Environmental Technology Award already in 1990. Thanks to their extremely compact design, the COMS can easily be applied in difficult or tight installation conditions.

The oil that has been separated and regained is also entirely clean and can be lead back to the oil tank through the oil drainage system. The long service life of the filter elements (at least one year) and the automatic recirculation of the oil mean that the contec oil mist separating system requires little maintenance and, thanks to its compact design, is suitable for use in difficult installation positions. The quick-action fasteners on the cover also mean filter elements are easy to replace.

How oil mist separators work

COMS comprise of a side-channel blower and the filter housing containing the filter elements. The side-channel blower causes negative pressure in the filter housing, into which the air containing oil mist is sucked. The air flows through the inlet pillar tube into the cavity in the filter housing and through to the filter elements. Here the fine oil droplets in the air are retained in the element and the air current carries them to the surface.

The filter elements have been designed specifically for cleaning exhaust air. contec Microfiber disposable filter elements offer exceptional filtration efficiency at very low pressure drops and, being 90%+ void (pore) volume, boast an open-cell quality that gives a very long service life. The elements are self-sealing and easily sealed into the housing via axial compression with an integrated special tie rod.

The special two-layer construction consists of an integrated supporting inner layer sandwiched between two bound outer layers. This design provides excellent bursting strength, optimises coalescing of the droplets and guarantees long-lasting, highly efficient removal of the oil aerosols. Since the filter elements comprise of several layers, extracted oil mist is prevented from being blown back through the elements.

The oil separated by the filter elements runs down along the outer surface of the elements to the bottom of the housing. It is collected in the ring space around the base of the filters. From here the purified oil is transported to the oil reservoir through the oil outlet and the connected oil hose. The inorganic composition of the filter elements is fully inert to all lubricating matter and virtually resistant to all chemicals in the air.

A long-lasting filtration system

It is not the elements themselves but the side-channel blower that determines the highest permissible operating temperature for the filter unit. The longer the filter elements are in operation, the more they become saturated with particles of solid matter. The pores become blocked and, as a result, the pressure resistance of the filters increases the longer they are in operation. For this reason the blowers of all COMS have been designed so that the required suction power can be maintained under a high degree of pressure resistance. This guarantees the filter elements a long and useful life.

The complete contec filtration system complies with directive 94/9/EC (ATEX) – equipment and protective systems intended for use in potentially explosive atmospheres – within the classification and operation conditions under markings II 2G c IIB T3 (ATEX Zone 1 for gas-vapour-mist) or II 3G c IIB T3 (ATEX Zone 2).

All COMS can be supplied with a recirculator for applications in ATEX Zone 1, an integrated emergency bypass and non-return valve, redundant motor/blower units on special frame constructions, hinged covers or an additional micro filter head piece to reduce the oil aerosols in the exhaust air to less than 0.1 mg/m³.

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