Variable speed drives save fan costs

Installing ABB variable speed drives has saved a brass manufacturer GBP 130,000 a year in energy costs. Boliden MKM, a leading manufacturer of brass and copper products, operates a brass casting plant at Aldridge, near Walsall, in the West Midlands. An inquiry by ABB Drives Alliance partner Central Electrical revealed that the company was looking to save energy and reduce the effect of the Climate Change Levy on its business. Central Electrical carried out an energy audit on the filtration plants, measuring the energy use over a typical week´s production. The result pointed to potential energy savings with ABB drives of at least GBP 25,000 a year on a 250kW fan and GBP 15,000 a year for each of three smaller fans - a saving of GBP 70,000 a year and a payback period of just 9 months. In the event, the total savings achieved for the installation proved to be much higher, some GBP 130,000, a figure verified by Boliden´s own energy measurement system. The energy audit covered the fume extraction filter plant for the brass casting process, consisting of two Luhrfilter filtration plants, one with a 250kW fan and the other with three 132kW fans. The airflow from the fans was controlled by restricting it using dampers. Ian Davey, Engineering Manager for Boliden, outlined the problems caused by the old system: "The orifice dampers we employed had to be closed to start the motors and then gradually opened up to the right position for operation. This was a complex method of control that lead to a lot of energy loss in the system. As we have a variable rather than a fixed load, we decided to employ variable speed drives to regulate the speed of the fans." The turnkey contract, which involved removal of the old damper system, supply and fitting of the drives, took two months to complete. Work was planned to keep breaks in production to a minimum. Fitting the drives also had other benefits besides energy saving. The swarf drying plant is served by three 132kW extraction fans. A pressure transducer mounted in the ducting feeds back to the variable speed drive giving good control over the operating parameters as well as emissions. Says Davey: "As well as the large energy saving, the variable speed drives also help us with associated environmental issues. We couldn´t have asked for a better project".