Huge energy and carbon savings can be achieved by investing in a new, modern compressor, but it’s important to consider where it will be sited, and if the pipework needs updating – as this can have a significant impact on efficiency. Andy Jones, Mattei general manager, explains
Although some compressors are housed in purpose-built, controlled plant rooms, it is just as common for them to be sited on the factory floor. While this is entirely acceptable, factory managers need to be mindful that environmental factors can affect a compressor’s efficiency, performance and wear and tear.
The main consideration is air flow into the compressor. It is important to avoid installing a compressor near to any heating equipment or source of heat. The air entering a compressor should be as cool as possible, as being denser, it is more efficient. If the air being drawn into the compressor is warm, the machine must work harder, reducing its efficiency as well as the lifetime of its parts. Cool air also helps ensure a compressor doesn’t overheat.
Secondly, the compressor should be sited away from sources of solid and gaseous impurities, as the air being drawn into the compressor needs to be reasonably clean. This can actually be straightforward; it might simply mean rotating the compressor so the air intake isn’t subjected to dust or fumes. Of course, if this isn’t possible then additional filtration can be used.
Thirdly, there must be a sufficient volume of air to serve the compressor. Air flow should be unrestricted and where intake ducting is used it should be of a sufficiently large cross sectional area to avoid excessive pressure drops. A pressure drop of 10 millibar reduces flow by one per cent.
If housed in a plant room the air vent must be large enough to supply an adequate volume of air. In some factories the door to the plant room is continually left open in an attempt to ensure there’s enough air circulating around the compressor, but even this might not provide suitable air flow, and could lead to pollutants being drawn into the air intake filter, blocking it prematurely, as well as the risk of unauthorised access to equipment that is often critical, and expensive.
Before a new compressor is installed it’s important to re-evaluate the existing pipework and system design, making changes and investing in upgrades where necessary.
The distance between the compressor and where the compressed air is actually used can have important implications, so should be assessed, especially if machinery or production lines have been relocated. Pipe runs should be suitably sized for the air delivery capacity of the compressor/s, with bends kept to a minimum.
For systems where the point of use and the compressor are close then a single line could be chosen, whereas for larger systems with many points of use a ring main is preferable.
When new energy efficient compressors are installed the pipework isn’t always upgraded, and in some cases it’s not even inspected for leaks and damage – meaning any energy efficiency benefits could be negated. In many companies in excess of 30 per cent of air generated is wasted through leaks in the system – so it would be entirely false economy to install a new, energy efficient compressor without firstly fixing any leaks that might exist. As a guide, for a company using 50m3 of compressed air per minute we estimate annual savings from fixing leaks would potentially be around £63,000.
Existing pipework might also be damaged, altering the efficiency of a system. If pipework is being replaced aluminium could be considered a more preferable material; it has good properties in terms of minimising friction and reducing energy losses, and is generally easier and quicker to install.
With the UK’s focus on energy efficiency, it is possible a new compressor installation will also include heat recovery, perhaps for the delivery of hot water. This needs careful consideration if it is to be an efficient addition to the system. If the hot water is, for example, used across the other side of the factory to where the compressor is sited, it isn’t going to be efficient.
To achieve optimum savings new compressors should be sited correctly, and the pipework and system layout suitably designed. We recommend a site assessment and audit are carried out before any new compressor is installed, to identify and rectify any issues.
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