Inverters achieve rapid ROI on 100kW fans

One of the largest building materials suppliers in the UK is benefiting from higher operating efficiency and ECA paybacks, achieving a short ROI (return on investment) on the installation of large inverter drives supplied and commissioned by Wyko. The drives are fitted on exhaust fans at six of the company's UK asphalt coating plants; calculated savings predict a payback period of just over a year and a half for the largest of the drives, a 150kW unit.

Installed as replacements for mechanical damper controls, this type of inverter drive can deliver a 40 per cent reduction in absorbed motor power while maintaining an equally effective airflow. Start-up and shut-down processes are also smoother, and speed control is more precise, extending the life of the motors and ensuring process consistency.

There are three sizes of fans in use on the coating plants and each has different estimated payback periods. The three sizes are 55kW, 110kW and 150kW. Calculations are based on an average airflow rate of 90 per cent, with the motors on an average 75 per cent load for ten hours per day, six days per week, and 50 weeks per year. Cost per kW-hour varies, but averages out at £0.04/kWh; motor power factor is 0.9. Since the original motors have been retained, motor efficiency remains at 90 per cent. The table below shows the calculated payback periods.

tstart{c,80%}

thead{Site|Fan size (kW)|Savings (£)|Payback time (years)}

tdata{1|150|6667|1.5}

tdata{2|110|4741|1.6}

tdata{3|110|4741|1.6}

tdata{4|110|4741|1.6}

tdata{5|110|4741|1.6}

tdata{6|55|2442|2.2}

tend{}

Jim Conner, Wyko Corporate Account Manager, comments: "Energy costs and environmental issues now, more than ever, are playing a major part in the operating cost of an efficient site." The products and services designed to address these matters range from inverters and soft-starts through to energy-related site surveys aimed at identifying the most efficient use of these products and the savings to be gained. Pumps, fans, dryer drums, mixers and crushers are all key areas for drive and control products.

Moreover, there are benefits over and above energy-saving aspect of the upgrade that are also being felt. The majority of the asphalt produced is consumed in major construction and building projects such as roads and other infrastructure projects; however, a growing trade is with localised contractors involved in small-scale projects who prefer to collect their material direct from company plants. With the added frequency of order collections, plant flexibility is essential and reliability is even more important.

Demand is also growing for specialist materials that are designed for specific end uses such as sports surfaces, decorative areas, industrial and commercial parking areas, which require precise control of the coating process. These products include innovative new lines such as cold-mix materials, coloured asphalt and low-noise road surfaces.

Wyko supplies, repairs or replaces over 10,000 motors and drives each year and specialise in all aspects of motor and drive selection and commissioning, from general energy-saving surveys to condition monitoring, and conducting motor usage surveys, supplying equipment off the shelf locally, to leaving consignment stocks and managing stores onsite.