In 1989 a centralized system with rotary vane vacuum pumps and compressors was installed. These were later replaced successively by Busch Mink claw vacuum pumps and compressors over a period of two years, a further significant step towards improved energy efficiency and economy with substantial reductions in operating costs.
The printing works Clausen & Bosse was founded in 1951, in the Northern Friesland town of Leck. The company expanded rapidly, and by 1968 had a printing capacity of 45,000 paperbacks and 6000 hardcover books per day. It is now owned by the CPI Group of France, and trades under the name CPI Clausen & Bosse GmbH. The company employs 580 staff at the Leck site, making it one of the top 100 employers in Schleswig-Holstein. In 2013, 40,000 tons of paper were processed and 87 million books were produced. The staff at the Leck works are particularly proud of the two "Quantum" ink jet printing machines. The first of the two was the largest digital printing machine in Europe when it was commissioned in 2011. CPI Books is the largest printing corporation in Europe, with 17 printing works in seven countries employing about 3000 staff.Since 1989 a centralised air system has supplied several sheet-fed offset presses and provided vacuum for a number of adhesive binding and book covering machines. Vacuum is used to hold and transport pages, and blast air is used to separate individual pages. Ring mains for vacuum and overpressure (blast air) connect the centralised air system to the individual presses and post-press processing machines. The system supplies the entire printing works with blast air at +600 mbar and vacuum at -600 mbar in three shifts around the clock.
Vacuum units equipped with Mink claw vacuum pumps
In 2012, works technical director Rainer Ketelsen faced the decision of replacing the original rotary vane vacuum pumps and compressors successively with similar technology, or seeking an alternative. This decision was prompted by equipment age: the vacuum and compressor units had operated for 50,000 hours and were becoming less reliable. Both the number of process interruptions and the cost of maintenance had increased. Rainer Ketelsen contacted Busch vacuum specialists, who recommended Mink claw technology. In contrast to rotary vane technology, the internal components of Mink claw vacuum pumps and compressors are contact-free. Two claw-shaped rotors contra-rotate in a housing without making contact with each other or the housing. No component wear takes place, and operating fluids are not required. The construction of Mink vacuum pumps and compressors is identical. In the same year, one of the rotary vane vacuum pumps was replaced by a Mink claw vacuum pump for evaluation purposes. Rainer Ketelsen found that claw vacuum technology uses less energy and delivers consistently high pumping speeds. No loss of performance due to wear was observed. As CPI Clausen & Bosse operates a strict environmental management system validated according to EMAS III, Mink technology is ideally suited to the company's ecological and commercial concepts.
This made the decision to use efficient Mink technology for the vacuum and blast air supply easy, and the systematic replacement of all the rotary vane units by Mink claw technology was completed in 2014. The centralized air system now comprises two vacuum units with two Mink claw vacuum pumps each, and three blower units with two Mink claw compressors each. Demand-driven output is possible by frequency-controlled motors, creating further energy savings. The control system for the entire plant was developed and installed by the CPI Clausen & Bosse management. It is fully automatic, and matches output to demand. The system is equipped with a central monitor screen.
Blower units equipped with Mink claw compressors
Rainer Ketelsen is pleased with the significantly reduced number of maintenance tasks. The original rotary vane vacuum pumps and compressors required regular vane replacement, and caused stoppages due to sudden vane failure. The average operating time of each vacuum pump and compressor is 4000 hours per year. The new Mink vacuum pumps and compressors now require only an annual gearbox oil change, and are otherwise maintenance-free. As a precautionary measure the input filters are checked once a month and cleaned if necessary.
According to Rainer Ketelsen, "Energy-efficient and low-maintenance Mink claw technology has significantly reduced operating costs, and due to the lower energy consumption CO2 emissions have also decreased considerably".
Automatic control system monitor screen