The importance of compressor siting

Published:  03 March, 2016

Significant energy and carbon savings can be achieved by investing in a new, modern compressor, but the efficiency of any machine is largely dependent on where it’s sited, and the condition and layout of the pipework. Andy Jones, managing director at Mattei, explains more.

As a result of technological advancements, investing in a new compressor will undoubtedly reduce operational costs and carbon emissions. Indeed, we have many examples we can cite where manufacturers have achieved substantial savings through updating the compressors in their factories and processing plants.

One of our customers, a leading food manufacturer, is expected to save around £150,000 over five years as a result of replacing large reciprocating compressors (which had been in operation for nearly 40 years) with three Maxima 75 high efficiency low speed compressors. For another customer, replacing a 12-year-old 90kW compressor with a Maxima 75 resulted in energy savings approaching £20k per annum.

Although replacing an ageing machine should result in energy and carbon savings, the new compressor must be appropriately sited, and the pipework must be in good condition with the layout designed to maximise efficiency and performance.

An assessment of the environmental conditions around the compressor is a good place to start. In particular, air flow, heat and pollutants should be considered.

To maximise efficiency, the air flow to a compressor should be unrestricted. Some compressors are installed in purpose-built plant rooms, but these are not always as ideal as you might think. Some compressor houses have just a small air vent, which might not provide sufficient air flow around the compressor. On some sites the door to the compressor house is left open to try and resolve this – but even this might not provide suitable air flow, and could actually lead to pollutants being drawn into the air intake filter, blocking it prematurely. It’s equally common to find compressors sited on a factory floor, and again environmental factors, such as fibres from production processes or various materials stored around the compressor, can affect air flow, and hence efficiency.

It is important to avoid installing a compressor near heat-generating equipment like boilers, furnaces or ovens. Cooler air is denser and makes the compression process more efficient, so if the air being drawn into the compressor is warm the machine will have to work harder, reducing its efficiency as well as the lifetime of its parts.

The air going into a compressor also needs to be reasonably clean and free from solid and gaseous impurities. In some cases this can be relatively straightforward – for example, at one site a compressor’s air intake was facing a sand blaster; simply rotating it 180 degrees dramatically reduced the dust particles entering the compressor and blocking the intake filter. If relocating the compressor isn’t feasible then additional filtration can be used to remove impurities.

In addition to assessing these environmental factors, it’s important to evaluate the condition and layout of existing pipework. Unfortunately this doesn’t always happen when a new compressor is installed – and if alterations aren’t made, energy efficiency savings could be negated.

If the pipework is showing signs of rust or corrosion we would recommend an upgrade, as this type of damage can alter the efficiency of a compressed air system.

It is also essential to check for leaks in the pipework, and repair any that are found. In many companies in excess of 30% of air generated is wasted through leaks in the system. As a guide, for a company using 50m3 of compressed air per minute we estimate the annual savings from fixing leaks would potentially be in the region of £63,000 – so it would be false economy to install a new, energy efficient compressor without firstly investing in a leak detection survey.

In terms of layout, excessive lengths and bends in the pipework lower efficiency, so pipe runs need to be suitably designed. For systems where the point of use and the compressor are relatively close then a single line could be chosen, whereas for larger systems with many points of use then a ring main would be preferable.

It’s also important to remember that although smaller diameter pipe may save on capital cost, greater pressure drops in the system would lead to a higher operating cost.

While new, correctly specified compressors can lower running costs and carbon emissions, in order to achieve optimum energy savings they need to be sited correctly and the pipework must be in good condition and the layout needs to be suitably designed. We would therefore always recommend that a site assessment, data logging/energy audit and leak detection survey are carried out before a new compressor is installed.

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