Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | JULY 2014 | 31 ing for up to 80 percent of the lifecycle costs of an aeration blower. Although the introduction of variable speed drives has helped to reduce energy consump- tion, this e ect has been limited. Given the cost of electricity consumption – and the associated CO2 emissions – water companies have been investigating alternative solutions with lower energy costs, improved operational e• ciency and reduced environmental impact. The new aeration blower system With the introduction of a new system combin- ing direct drive, high speed permanent magnet motors, active magnetic bearings and a magnetic bearing controller, it is possible for energy con- sumption to be signi• cantly reduced. The new aeration blower system comprises a high-speed permanent magnet motor (PMM) available in sizes 75 kW-350 kW, active magnetic bearings (AMB) and integrated AMB control system. There are a number of features that enhance performance. For example, unlike tra- ditional induction motors, the PMM maintains e• ciency at half-load and half-speed operation. An energy-e• cient high speed motor/mag- netic bearings system for aeration blowers also uses fewer mechanical parts than a traditional drive system, which means reduced mainte- nance, while powerful built-in monitoring and diagnostic capabilities maintain high perfor- mance and reliability. Additionally, the new system provides higher e• ciency under nominal or partial loads, is more reliable and quieter, and is almost maintenance free. Energy e• cient aeration blowers with high ' Innovations ● Higher effi ciency with nominal and partial loads (10% gain over conven- tional motors) ● Increased equipment reliability ● Virtually no need for maintenance ● Decreased construc- tion costs due to a more compact design ● Powerful diagnostics tools ● Optimised process control ● Prolonged overall oper- ating lifetime ● Reduced noise ● Meets regulation requirements speed motors and magnetic bearing systems now have the capability to reduce energy consump- tion by up to 40 percent. In wastewater facilities, the aeration blower system can demand as much as 80 percent of the plant's total energy consumption, so the new solution o ers the potential to make huge energy savings. When used in one of the largest 350 kW blowers it may result in annual savings of 500,000 kWh, which equals a 375-ton reduction in CO2 emissions. This innovation represents a new and sustain- able approach to the problem that targets the market challenges faced by the water and waste- water industry, namely a high speed motor/mag- netic bearing system for aeration blowers that meets the demand for energy e• ciency, and the need for a reduction of maintenance and service costs, as well as the requirement to comply with air quality and safety standards. Compared with a traditional blower, one of the new wave of motors in a 350 kW centrifugal air blower o ers payback on investments in one year from energy savings alone. Given the cost of electricity consumption – and the associated CO2 emissions – the new aeration blower solution o ers the opportunity to lower energy costs, improve operational ef- • ciency and lifecycle costs and reduce environ- mental impact. Kevin Walker is product manager bearing and units at SKF Used in one of the largest 350kW blowers the new system may result in annual savings of 500,000 kWh, which equals a 375-ton reduction in CO2 emissions. ' In action A wastewater treatment facility in France serving a city of 100,000 inhabitants and local industry had been operating with four 80 kW lobe-type blowers, and these presented the operator with several issues, including frequent breakdowns, high energy consumption, high noise levels and treatment process problems. A er replacing the lobe blowers with two new 120 kW centrifugal blowers that featured the SKF high-speed permanent magnet motor solution, the treatment process improved signifi cantly. Noise levels fell from 110 dBA to 70 dBA, the facility achieved a regulation of the fl ow rate, and maintenance demands dropped considerably. The bottom-line reductions in energy use were even more impressive. A er only a year in operation, the blowers equipped with the SKF solution cut plant CO 2 emissions by 375 tonnes and operating costs by 54,000 euros. The upgrade to more effi cient magnetic bearing blowers off ered a short payback (less than two years) from the energy savings alone.

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