The March meeting of Yorkshire Branch returned to its normal venue of the Bridge Inn, Wetherby, to hear a talk by Peter Schofield, group manager of the industrial products division of William G Search Limited.
Peter’s topic was by way of a general introduction to compressed air and its uses in industry. Compressed air is merely a store of compressed atmospheric gases (Nitrogen, Oxygen and Carbon Dioxide, plus trace elements of other gases), which can be used as a store of energy to carry out work or processes.
The use of compressed air is now so widespread across many industries that it is considered the fourth utility after electricity, natural gas and water. However, compressed air is more expensive than the other three utilities and so system design and efficiency are important considerations.
The basic components of a system are the compressor to squeeze atmospheric air to a higher pressure, an air receiver for the compressed energy, air filters to remove impurities, dryer to remove moisture and a distribution system to take the air to the point of use.
The system design needs to consider the flow rate and pressure required, as well as the demand profile (maximum, minimum and average), together with the application, which will normally determine the cleanliness required, a hospital will require a different standard to a tyre depot, for instance. The quality can be specified using ISO Standard 8573-1. The lifetime cost of the system from purchase, installation and maintenance as well as energy cost should also be evaluated.
The focus with any compressed air system should always be the operating cost. Variable speed drive compressors suit 90% of applications and can reduce system operating costs by up to 35% per annum. Compressor assemblies with in-built dryer and filter units keep pressure drops to a minimum and improve system energy demands. Consideration must also be given to energy efficient distribution systems from storage to point of use.
In terms of numbers, some useful points to note are that 70% of the cost of a compressed air system is taken up by energy consumption. 1kW of compressed air requires 8kW of electricity to create it. Reducing operating pressure by 1 bar can typically save 7% of energy costs. After 5 years, air leaks can often account for 20% of air consumption. Many systems continue to run out of production hours and therefore continue to feed leaks. Improved equipment selection will provide further savings.
Peter then went on to illustrate some typical industrial systems and where efficiencies and savings could be made, following which he answered a number of questions from the floor. Technical Committee Chairman Aidan Ranftler proposed the vote of thanks to Peter Schofield.
For further information please contact William G Search Ltd www.compressive.co.uk.