Nordic Recycling operates Europe's largest single-line materials recovery facility (MRF) at Tilbury in Essex. The processing machinery was designed by Ken Mills Engineering (KME) and is believed to be the most advanced of its kind in the UK. It features a large number of automated screening stages that enable the extraction of different types of dry recyclable materials, plus a series of automatic balers, all linked by a feeding and materials handling conveyor system with a total length of several hundred metres.
Some 50 gearboxes from Nord Drivesystems are deployed in this handling system - all helical bevel units, selected for their low noise emissions and high efficiency. Indeed, at more than 95%, the efficiency of these gearboxes is having a big impact on the overall energy efficiency of the plant, which typically operates for around 16 hours per day.
The MRF has a nominal capacity of 25 tonnes/hour, and is expected to process at least 100,000 tonnes of mixed dry recyclable materials a year, which might otherwise go to landfill. Among these materials are some 50,000 tonnes of reclaimed paper, which will to be baled and shipped to Holmen Paper in Sweden for recycling into fresh newsprint.
The MRF process machinery has a design life of 25 years, and part of KME's contract responsibility is to provide a 24/7 maintenance service. Not surprising, therefore, that reliability was high on the list of KME’s requirements when specifying the drive systems. Good previous experience with the company's products prompted KME to choose gearboxes from Nord Drivesystems. KME had previous experience of the latter’s gearboxes on another materials handling system it built for a 15 tonnes/hour MRF on Merseyside. In near-continuous operation since 2006, the gearboxes at this site have performed reliably without a single failure. KME's screening systems supplier also standardises on Nord gearboxes, providing a second endorsement of the product's reliability and quality. KME’s MRF project manager, Adam Moore, pays tribute to the Nord products:
"The demands of designing material recovery facilities means that wherever possible we employ very high quality and field proven automation components. We've now used power transmission components from Nord Drivesystems for over two years, and are very happy with the performance and reliability."
Nord helped KME to specify the gearboxes, choosing sizes that reflected a combination of economy and operating safety margins. The underlying performance margin built into the conveying system, and other elements of KME's processing machinery, has been demonstrated many times since the Tilbury plant started operations in October 2007, as the nominal capacity of 25 tonnes/hour is regularly exceeded, sometimes by as much as a third.
Helical bevel gearboxes from Nord's SK9000 family are used on the conveying system drives and these provide the necessary right-angle connection for this low-speed power transmission application. As well as ensuring smooth, low-noise meshing for the conveyor drives, the helical bevel cut teeth also provide substantially increased efficiency compared with more commonly used worm gears. Indeed, the 25% greater efficiency available from the helical bevel units equates to energy cost savings of many thousands of pounds a year for the Tilbury site.
The gearboxes were assembled for KME at Nord's UK facility in Abingdon, with ratios to suit the application. The units were also painted according to KME’s requirements, ensuring that they were ready-to-connect on site.