The right site: Where to install a compressor and associated infrastructure
Published: 14 April, 2020
Optimising a compressed air system’s performance is not just about the compressor unit. Where it is installed and how the associated infrastructure is designed also has an impact on a system’s energy efficiency, how quickly a business will see a return on its capital investment, and in some cases, even its ability to comply with environmental controls. Martin Chitty, business development manager at Mattei UK, explains how to choose a suitable site to install a compressor.
Back in the day, air compressors were placed well away from the production area, often in a separate building due to noise. Whilst modern compressors are much quieter and can be installed on the same premises, the need to maximise energy efficiency and space utilisation, together with changes in production processes and environmental controls mean that there are now a whole host of factors to consider. So, what exactly should managers bear in mind when deciding on where to put an air compressor?
Particles and pollutants
Many manufacturing environments are plagued by a high concentration of airborne, small sized particles that are a side effect of the actual manufacturing process itself. From cooking ingredients in a food processing environment, to oil mist which further attract other contaminants, they can adversely affect compressors even if equipped with high efficiency intake filters. These particles can block up vital parts of a compressor. Furthermore, the compression process also makes the impurities more concentrated, which can significantly reduce the quality of your compressed air.
Rotary vane compressors cope better than screw compressors in many aggressive environments due to a greater tolerance to contamination by airborne particles. Nevertheless, it is still best practice to avoid locations with excessive airborne pollutants, such as loading and unloading areas.
Air compressors move a considerable amount of air during their operation. A poorly ventilated area would cause a compressor to run unnecessarily hot, resulting in reduced efficiency, more frequent service intervals ultimately, shortening its life span. If the compressor needs to be housed in an enclosed area where the only way to get fresh air to the unit is to cut an opening in the wall, weather louvres should be considered to protect the compressor and the intake air from harsh weather. However, a larger intake will be required to compensate for the reduced surface area as a result of the louvres.
In the winter during sub-zero temperatures, a compressor will not start if its oil temperature falls below the minimum threshold. So in addition to weather louvres, consideration should be given as to whether or not internal heaters should be installed if there is only one compressor, with no other form of maintaining a minimum temperature. Where there are multiple compressors, some of the waste heat could be redirected back into the compressor house rather than being expelled to atmosphere.
Up to 95% of a compressor’s kilowattage is discharged as heat. Typically, 80% of this waste heat is recoverable. So as a minimum, it’s worth using it for space heating. For this to be an effective strategy, the compressor should be located near to where the heat is required without being too far from where it needs to be discharged in the summer.
Alternatively, waste heat from water-cooled compressors or those fitted with a heat exchanger can be used to provide hot water for the production process, heating or sanitary purposes. For example, a compressor can be located next to the factory’s boiler. Rather than using cold water as make-up water, it can be pre-heated using heat recovered from the compressor. One significant advantage is that hot water is needed year round. On the other hand, demand for space heating is seasonal which should be taken into account when calculating the value of this recoverable heat.
Whilst rotary vane compressors run significantly slower than screw compressors and produce less noise, it is still essential to ensure that any noise associated with the heat discharge process complies with local environmental controls. With this in mind, it is best practice to direct ducting used to expel heat away from noise-sensitive areas. Where this is not possible, noise attenuation measures within the ducting will be required.
A compressor’s cooling fan has a specified maximum loading which cannot be exceeded. This is why ducting for heat discharge needs to be correctly sized because restrictions can lead to excessive back pressure on the fan and damage the compressor’s cooling system.
The distance between the compressor and where the compressed air is used can have important implications in terms of system efficiency. Whilst it is preferable to locate a compressor as close as possible to where compressed air is used, this may be restricted by access to power supply as well as the other factors highlighted in this article. In many such instances, it is cheaper to install pipework to take compressed air from where it is generated to point of use, compared to the cost of installing copper cables.
However, pipework should be designed to ensure minimal pressure drop. Excessive lengths and bends lower efficiency, so pipe runs need to be suitably sized and laid out. Where bends areunavoidable, use swept bends and tees as these reduce pressure loss.
You can’t predict where compressor air is needed in the future. But you can design the associated pipework to accommodate changes to the factory floor layout in the future. Correctly designed ring mains can be used so that sections of the pipework can be isolated to make modifications without disrupting the whole system.
Maintenance and access
It might seem obvious, but ensuring that the compressor can be easily transported to where it needs to be installed is sometimes overlooked. It is not just a matter of measuring the footprint available for the compressor; any pinch points en route to its designated location need to be taken into account.
For example, will the compressor need to be manoeuvred through doorways and gaps? If the unit cannot fit though a doorway, and removing neither the doorframe nor even a wall can solve the problem, craneage will have to be considered and factored into the cost of installation.
It is preferable to install a compressor on the ground floor, with space allowed for expansion. Where this is not possible, careful planning will help to minimise headaches later down the line when your compressor arrives on site. Weather extremes can also influence the choice of location; compressor will need to be raised off the ground if it is going into a floodprone area. South-facing roof spaces are best avoided due to the possibility of excessive solar heat absorbed by steelsheeted roofs.
Once a compressor is fully operational, engineers will need ample space for maintenance and servicing. Siting the equipment in a suitable space will ensure that compressor doors can be opened and that engineers can safely lift components in and out. Each site is different and can present a wide range of challenges for managers to overcome. But by working with your compressor supplier and planning well in advance, a suitable site can be identified to ensure a smooth installation and optimal compressor performance thereafter.
For further information please visit: visit www.mattei.co.uk