At its Hagen site, Stora Enso produces almost half a million tons of paper per year, which equals almost 6.250.000.000 A4 papers. Close to 170,000 m3of compressed air has to be generated every day to operate the paper machines, calendars, winders and cutters. Five compressors supply the internal compressed air system and cover the highly fluctuating demand, which at peak times can rise rapidly by up to 5000 m3/h.
In 2010, the company decided to optimize its compressed air system and installed an ES 130 T central controller, as well as a ZR 315 VSD compressor from Atlas Copco.
The ES 130 T controls several compressor sizes and types from various manufacturers. The system tests, stores and analyzes to ensure that the most suitable compressors are activated. As a result, the output of the five connected machines is geared, in terms of overall energy, towards achieving the optimum operating point and is continuously adjusted to meet the demand. This optimized operation not only means that energy consumption, CO2 emissions and costs are drastically cut, but also has a positive impact on the service life of the compressors.
Stora Enso has also invested in a new ZR 315 VSD (Variable Speed Drive) compressor. Graduate engineer Stjepan Horvat, responsible for the compressed air supply in the Hagener plant, says: "We had the problem that our high-performance compressors were constantly toggling between full load and idling, with the controller sometimes requesting a turbo for just two minutes."
After the installation upgrade, the original turbo compressors - operating in their 70 to 100% turndown range - now provide the required compressed air base load, while the ZR315 VSD - thanks to its speed regulation - operates primarily in the partial load range to respond to the varying demand for compressed air at any time. A proven combination of compressor technologies avoiding extremely long idle times, a lot of wasted energy and high CO2 emissions.
Once the central controller and VSD compressor had been installed, Stora Ensa's energy consumption fell by 30%. As a result, the company's entire investment has been amortized within one year.
At Stora Enso, sustainability and energy saving have yet another dimension: The heat discharged by the compressors is used twice. In winter, it heats up the production hall and in summer, it pre-heats the process water required for production.
Atlas Copcois an industrial group with world-leading positions in compressors, expanders and air treatment systems, construction and mining equipment, power tools and assembly systems. With innovative products and services, Atlas Copco delivers solutions for sustainable productivity. The company was founded in 1873, is based in Stockholm, Sweden, and has a global reach spanning more than 170 countries. In 2011, Atlas Copco had 37 500 employees and revenues of BSEK 81 (BEUR 9). Learn more at www.atlascopco.com.
Oil-free Airis a division within Atlas Copco's Compressor Technique business area. It develops, manufactures, and markets oil-free air compressors for all kind of industries worldwide where the air quality is vital, and oil-injected compressors for less critical applications. The division focuses on air optimization systems and quality air solutions to further improve customers' productivity. The divisional headquarters for the division is located in Shanghai with main production facilities in Belgium, China, India and Brazil.