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More than one answer to energy question

25 January 2013

In recent years, variable speed drive compressors have become a popular choice. However, Andy Jones, general manager at rotary vane compressor manufacturer Mattei, explains why they should not be treated as an automatic s

In recent years, variable speed drive compressors have become a popular choice. However, Andy Jones, general manager at rotary vane compressor manufacturer Mattei, explains why they should not be treated as an automatic solution for every application

Compressed air can typically account for around 10% of a business' total electricity costs; this can rise to 30% in some industries. Therefore, when looking to purchase a new compressor either to replace an existing machine or to meet new demand, energy efficiency must be the top consideration.With the Government heavily focused on driving the green agenda and looking at ways to lower the UK's carbon emissions and reduce energy consumption, industry is under increasing pressure to account for its energy usage and look at ways to make savings.

Fourth utility Compressed air is often thought of as the fourth utility, yet not every business considers whether its compressed air system is truly efficient. It's important to remember when buying a new compressor, the initial capital outlay actually makes up a very small part of total lifetime cost. The main expense will always be the energy required to produce the compressed air, so it's vital the compressor is right for the application.

VSD machines Compressor manufacturers have been working hard to make compressors more efficient and the introduction of variable speed drive machines was definitely a major advancement. VSD compressors work by adjusting the air supply according to demand, in contrast to conventional, fixed speed compressors that give a constant air supply. By precisely matching power consumption to the required load profiles, VSD compressors reduce energy losses, typically producing savings of 30% or more (based on Mattei's Optima VSD compressor).

While variable speed drive compressors have undoubtedly helped countless businesses to reduce energy consumption, there is a misconception that simply installing such a machine is the only answer to improving the efficiency of a compressed air system. VSD compressors will only save energy if there are peaks and troughs in the air requirement - this sounds obvious but it's surprising how many are installed in applications with constant demands.Many manufacturing companies believe, or are told by their compressor supplier, that their air demand is variable and so invest in this type of machine - assuming it will automatically save them energy and money.

Understanding demand The only way to confirm if a company requires a variable or fixed speed compressor is to obtain an accurate understanding of air demands. Before a company invests in a new compressor,Mattei always recommends an initial data logging exercise, which evaluates the business' compressed air needs and the efficiency of the system by recording and measuring air consumption profiles over a seven day period. This is usually followed by discussions to identify any unusual patterns or planned process changes.

Data logging only provides a snapshot of compressed air activity, but, as long as it's a typical week, it identifies whether a company has highs and lows in demand for air, or whether requirements remain constant. With a true picture of a business' air demands, it is then possible to make informed decisions as to the type of compressed air system needed.

Understanding there is a need for both variable and fixed speed compressors,Mattei continues to invest in both technologies. For companies that do require a VSD compressor, it can offer a solution from its Optima range, with off load power consumption below 10% and available in outputs from 11 to 200kW, with a capacity range from 1.19 to 35.5m3/min.

For systems with constant compressed air demands operating for more than 4000h per annum,Mattei has developed the Maxima fixed speed range, available in outputs from 30 to 160kW with a capacity range from 6.45 to 31.8m3/min and uses as little as 5.4kW of electricity to produce a cubic metre of air.

For companies with a constant base load and a variable demand on top, a combination of Maxima and Optima compressors can provide savings.

With industry becoming burdened by legislation to encourage it to lead the way with environmental best practice, businesses need to find ways to deliver genuine energy savings rather than 'green washing' with changes that sound impressive but don't deliver.

Being able to adjust compressed air supply according to air demands by utilising VSD compressors can be a solution, but it's important to ensure they are only specified when they are actually going to reduce a business' energy consumption and costs.