January 2022

28 n PAPER AND PACKAGING January 2022 www.drivesncontrols.com Energy efficiency upgrade looks good on paper A t its facility in Weinfelden, Switzerland, Model Group develops, produces, and supplies high-quality packaging made of solid and corrugated cardboard, ranging from simple transport packaging to highly refined chocolate and perfume boxes. The site operates two huge paper machines, each almost 80m long. The machines, powered by dozens of electric motors, operate 24 hours a day, seven days a week, recycling raw materials to produce the paper that the group uses to manufacture some 1,500 million square meters of corrugated board every year. Paper production is an extremely energy- intensive process, so when one of the paper machines at Weinfelden was approaching the end of its service life, the family-owned Model Group was keen to explore upgrade options that would deliver a boost in energy efficiency. “Recycling and energy-efficient production have the highest priority for us, from an ecological as well as an economic point of view,” explains Philipp Lenhard, the site’s technical manager. “This priority applied to the renewal of the drive systems for the paper machine. The variable-speed drives were legacy models that suffered from a lack of spare parts, while the motors dated from 1991 and required an extensive overhaul. The modernisation project was planned around Model Group’s six-day summer shutdowns in 2019 and 2020. The new equipment was delivered to site, ready for fast-track installation and commissioning. Fitting new motors and drives to the existing machinery avoided the costs of overhauling the existing motors, while taking advantage of Swiss government grants available for energy efficiency improvements. In 2019, the VSDs were replaced with ABB ACS880 Multidrives. A year later, a total of 36 electric motors were replaced with IE4 machines – the highest standardised energy efficiency classification for AC induction motors. These were also supplied by ABB. The use of IE4 motors enabled Model Group to access Swiss Federal funding for the project which would not have been available if it had chosen IE3 motors. “This grant covered around 32% of our total investment,” Lenhard reports. “In effect, the upgrade in efficiency rating paid for the motors from the start.” Delivery and commissioning went ahead as planned, with the paper machine able to start up again in August 2020, but operating more economically and quietly than before. Calculations by Model Group reveal that the high-efficiency motors and drives are saving it up to 900MWh a year – equivalent to the annual consumption of 200 typical Swiss homes. There are also other important benefits from the upgrade. Previously, the 2.5m-wide paper web ran through the machine at around 800 metres per minute. Now it runs at 900m/min – a major increase in productivity. Furthermore, the new drives will eventually allow the machine to run at 1km/min when other upgrades are carried out. So, the machine’s production speed has already increased by 12.5%, with potential for a total improvement of 25%. The motor speeds have also been reduced from 1,500 to 1,000 rpm, which has made it possible to optimise or eliminate gears, thus reducing friction significantly. The final result is faster production, significant energy savings and a projected ROI (return-on-investment) of less than five years. “The success of this project for Model Group is a perfect illustration of how energy efficiency is not an added business cost,” points out Stefan Floeck, president of ABB Motion’s IEC low-voltage motors business. “Instead, modernisation with the latest energy-efficient motors and drives contributes directly to improved bottom-line performance, as well as helping to reduce carbon emissions.” n A Swiss packaging manufacturer has modernised a key paper-making machine using high-efficiency motors and VSDs. The upgrade has boosted productivity and reliability, and cut energy consumption by up to 900MWh a year – giving a projected payback of less than five years. By installing IE4 motors on its paper machines, Model Group has qualified for Swiss government grants available for energy efficiency improvements