Optimised pneumatic filters and other ways to save energy

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John Hill, the Marketing Services Manger at Parker Hannifin's Pneumatics Division, explains how filtration technology can substantially reduce energy consumption and costs.

With escalating energy prices and growing environmental awareness, reducing the energy consumed by pneumatic equipment is now a major concern for businesses across a wide range of industries. Pneumatic systems have been estimated to consume between 10 and 15 per cent of all electrical energy in a typical manufacturing plant, so increasing the efficiency of equipment that uses compressed air can have a considerable impact on an organisation's bottom line, as well as its carbon footprint.

The focus of attention has generally been on reducing the energy consumption of compressors, but what is not widely recognised is that considerable energy can be wasted downstream of the compressor. By improving the efficiency of FRL (filter/regulator/lubricator) units, valves and cylinders, plant managers can increase the efficiency of pneumatic systems simply and cost-effectively. As an added benefit, unplanned maintenance and equipment downtime can be reduced as well.

Firstly, it is important to ensure that the intake filters of compressors are clean and in good working order. Failure to do so can lead to falling output pressures and, as a result, increased energy consumption. Dirt and other contaminants can be prevented from entering filters by keeping the area around each filter clean, preferably with some sort of barrier.

Likewise, the efficiency of aftercoolers can be optimised by carefully monitoring the temperature of equipment and fitting effective temperature gauges. The gauges should be installed on the aftercooler at both the cooling water inlet and the compressed air outlet. It is also important to position air dryers correctly. The location of a refrigerated air dryer can have a considerable impact on its performance; the area should be as well ventilated and clean as possible, allowing heat to be expelled easily and preventing dirt from affecting the performance of the dryer.

Preventing particle contamination in compressed air systems is vital if energy consumption is to be minimised. Although relatively course filters fitted to the compressor intake are sufficient to protect the compressor, it is difficult to prevent particulates below five micron being drawn in; these pass through the compressor and can be fed under pressure to downstream equipment, along with moisture and vaporised compressor oil.

While this may not initially sound significant, a typical factory contains 140million particles of dust, grit and pollen per cubic metre of air; compress this to seven bar and the density will exceed 1100 million particles/m3. When combined with moisture and oil, these contaminants will gradually accumulate on the internal surfaces of valves and cylinders, leading to wear, inconsistent operation, and premature failure.

The latest generation of in-line air filters are highly effective, removing particulates and other matter without a significant drop in pressure across the filter. Modular technology is now available, such as Parker's Moduflex system, to make building and installing a bespoke air filter simple and cost-effective.

Using these modular FRL units, a complete FRL assembly can be constructed in less than half the time taken for conventional devices, without the need for tools or special training. As a result, considerable energy savings can be made extremely quickly and simply. The modules are manufactured in aluminium to combine robust construction with low weight, making them suitable for a wide range of industrial applications. Filters, regulators, lubricators. and dump and ball valves can be connected together to form a completely integrated filtration package.

When specifying these filters, it is important to size them correctly to ensure that a higher degree of filtration does not have an adverse affect on flow rate, pressure drop and service intervals. Similarly, correct sizing of valves and cylinders is crucial to optimising the efficiency of a pneumatic system and minimise energy consumption and costs. The best way to ensure this is to work closely with the supplier, who will be able to help determine: the amount of thrust or clamping/holding force required; the air pressure available; and the operating efficiency of the cylinder, based on its type or method of manufacture. Likewise, the required flow rate, working pressure, and acceptable pressure drop across valves should also be considered carefully.

With the need for companies to protect themselves against rising energy costs and minimise their environmental impact, reducing the energy consumption of pneumatic equipment is now more important than ever. By investing in the latest generation of filtration technology, and ensuring systems downstream of the compressor are maintained correctly, these objectives can be achieved simply and cost-effectively.

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