There’s a growing demand for higher-quality compressed air in chemical / process and medical applications. As a result, the discussion on how to best produce it is constantly debated.
Definition
The term “oil-free compressor” refers only to the compression chamber, not the compressor system as a whole or the resulting compressed air quality.
Also bear in mind that “oil-free” is a vague statement used within the compressed air industry and is dependent upon what is drawn into the compressor air intake and we will still require purification equipment in both the compressor room and at the point of use to ensure “Oil Free Air”
No single process or product will deliver high-quality compressed air, often referred to as “oil-free” compressed air.
To achieve this we need comply with the quality classes specified in standard ISO 8571-1. Only these provide the precise definitions of OIL FREE AIR
Compressor manufacturers have different ranges of ‘oil-free’ or oil-cooled systems but these invariably need primary or secondary downstream purification systems.
Air compressors draw in huge amounts of atmospheric air, which continuously fills a compressed air system with contaminants such as water vapour, micro-organisms, atmospheric dirt & oil vapour.
When the air has passed through the compression stage, the after-cooler will also condense water vapour into the compressed air in both a liquid and aerosol form.
This will then pass into the system piping that distributes the compressed air and into an air receiver or some form of storage device, it is this pipework and receiver which also contributes to large amounts of contamination.
They also act as a means of cooling the warm, saturated compressed air which in turn causes more condensation, adding liquid water into the system.
This saturated air and liquid water can lead to corrosion, pipescale and in some cases microbiological growth.
Normally we say that there are ten contaminants found in a typical compressed air system that need to be filtered and removed
These are:
- Liquid Water
- Water Vapour
- Water Aerosols
- Oil
- Oil Vapour
- Oil Aerosols
- Atmospheric Dirt
- Microorganisms
- Rust
- Pipescale
Liquid oil and oil aerosols are introduced by an oil- lubricated compressor. The filtration equipment needed to remove the remaining contaminants also removes these liquid oil and oil aerosols.
When installing an ‘oil free’ compressor it is quite common to omit one level downstream filtration.
Filters in a compressed air system will typically be a coarse and a fine filter set-up which is often believed that one of these filters is a particulate filter and the other is an oil removal filter.
Wheras in reality the two filters used are coalescing filters, and are probably the most filters in the system as they combine to remove varying levels of contaminants (Water Aerosols, Oil Aerosols, Atmospheric dirt, Microorganisms, Rust & Pipescale).
The first filter is a ‘general purpose filter’ which protects the ‘high efficiency filter’ from bulk contamination.
SOLUTION
All compressed air systems need filtration and to achieve this and we have a number of filters which we can install to remove most of the contaminants, however to remove oil from a system we need to install some form of catalytic convertor – BEKOKAT.
The BEKOKAT catalytic convertor works by converting gases/ hydrocarbons by the process of oxidation producing less harmful gases typically Carbon Dioxide and Water vapour
This operation is not dependant on the temperature and humidity of the compressed air to be treated but will continuously supply air with a residual oil content of less than 0.003mg/m3
The basic formula for this conversion is CnH2n+2 +O2 = H2O + CO2.
The BEKOKAT is also ideally suitable for the retrofitting of existing compressor stations. In this manner, a compressor station with existing oil-lubricated compressors can easily be transformed into an oil-free compressed-air provision system without the need of expensive investments for new oil-free compressors. BEKOKAT systems are not only highly effective, but also very environmentally friendly.
For more information, please contact BEKO TECHNOLOGIES on 01527 575778 or email us info@beko-technologies.co.uk.
www.beko-technologies.co.uk
