Compressed air and steam are vital forms of energy for any plant; but often they are the most misused and abused forms of power. They also happen to be the most expensive. So what can a compressed air system optimisation do for you? According to Allen Cockfield, CEO of specialist air treatment company, Artic Driers International, an optimal design for the compressor system is vital to obtain the best performance from your capital investment and receive the best return on your electrical energy. The optimisation process should consider the following factors.
Compressor station position: The position of the station will influence the pipeline length. Longer lines can easily lead to airline pressure losses. Pressure losses equate to power wastage and higher operating costs. Compressor stations should ideally be in the centre of the factory.
Waste heat recovery: The waste heat ejected by an air compressor can be used for a variety of functions – ablution block water heating and production process heating to name but two. This form of heat recovery will reduce the overall cost of compressed air dramatically; 98% of the kilowatts used in the compressor can be recovered.
Decentralised compressor stations: On larger systems it may be advantageous to have multiple decentralised compressor stations. This can reduce long pipeline runs and the pressure drops associated with them.
Pipeline sizing and design: Undersized airlines in the compressor room are very common and are one of the biggest causes of energy wastage. They choke the air flow from the compressor room to the plant and the resulting back pressure is often enough to create a false signal for the compressor, telling it to offload when in reality the plant is suffering from a lack of line pressure. Don’t assume that the discharge flange on the compressor is the line size to use, often it’s too small.
A pipeline design that allows for minimal pressure drops as well as future plant expansion is a vital part of the optimisation process. It must also allow for drainage of condensates, even if low dew point dryers are in place, as well as the removal of any oily waste condensates for proper disposal.
Compressor selection: Prior to installing a new compressor station, a qualified air energy auditor should ensure that compressed air is going to be used effectively at the correct pressure, and with the correct air quality. Base load compressors can then be selected confidently and variable speed units can be used to balance the final top end air load. Remember to allow a degree of excess for future expansion. Review the need for oil-free or lubricated compressors – oil-free compressors can carry a heavy price tag if the air quality requirement is not needed for the majority of the plant. A review of the compressor’s kilowatts consumed per cubic metre produced must be undertaken prior to purchase.
Compressed air treatment: The correct selection of inline filters and dryers is also essential to ensure pressure losses are minimised. Over-specification will lead to increased capital and operating costs. However, compressed air that is not fit for purpose on the production line will lead to premature failures of pneumatic equipment or product rejects. Both erode profits and increase operating costs. Using a refrigeration dryer for general air treatment in the compressor room is always a cost efficient option.
“With South Africa’s rising power costs, auditing and optimisation are a real need and the cost savings that can be achieved are huge,” concludes Cockfield.
For more information contact Allen Cockfield, Artic Driers International, +27 (0)11 420 0274, allen@articdriers.co.za, www.articdriers.co.za
| Tel: | +27 11 420 0274 |
| Email: | allen@articdriers.co.za |
| www: | www.articdriers.co.za |
| Articles: | More information and articles about Artic Driers International |
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