At the Christinen-Brunnen mineral water plant in Bielefeld, two dry-compression rotary screw compressors combined with two refrigeration dryers and various filters produce food-grade control air and supply air for the treatment, mixing and bottling of mineral spring water. And naturally they meet the highest possible energy efficiency and reliability standards.

In many industrial applications, it is important for the compressed air to be as clean as possible. One example is the beverage industry. Franz Bunte went into the beverage trade in 1895. His business grew rapidly and he was soon well known across the region of eastern Westphalia. In 1932 Franz Bunte’s son-in-law Paul Gehring took over the business, which has since operated under the name Gehring-Bunte. After securing a licence in 1934 to make and sell Coca Cola within a 30-kilometre radius of its headquarters, Gehring-Bunte expanded into the beverage production business. The third generation assumed control of the family business in 1955, when Paul Gehring’s sons Dr. Paul Gehring and Werner Gehring took the helm. They made the company what it is today: a leading seller of brand-name beverages.

This success was built on Christinen-Brunnen, a mineral water plant in Ummeln (at that time still an autonomous community half-way between Gütersloh and Bielefeld, and now part of the Bielefeld district of Brackwede). The new company’s first bottle, labelled “Teutoburger Mineralbrunnen”, left the production line on 1 May 1966.

That marked the start of an upward trajectory that has continued right up to the present day – thanks to the brand’s high-quality range of mineral water products. Through the embrace of innovation and skilled brand management, the company has established and steadily expanded its market position.

Today “Christinen” is among Germany’s most recognised mineral water brands and is also very popular across Europe. Since 1994, the company’s activities have been complemented by a bottling operation in the town of Wiesenburg am Fläming in the state of Brandenburg and the products of the Erkrath mineral spring near Cologne.

In 2011 Gehring-Bunte had a total output of 155 million litres bottled in 300 million containers by approximately 220 employees.

Compressed air – food-grade and very economical

Both as an energy source and control medium, compressed air is used everywhere in a bottling plant. However, these applications are subject to stringent air purity standards. A basic air supply is also needed for the boosters of the two PET bottle production lines. Consequently, when it came time to replace the entire compressed air system, it was clear from the outset: the new rotary screw compressors would have to be dry compression models. Moreover, the compressed air treatment equipment would have to ensure the necessary quality on a reliable basis.

Compressed air stations often generate more compressed air than is actually used, as the end users’ requirements vary over the course of the day. As a result, there is often an imbalance between production and consumption. The best approach is therefore to start with an analysis of the actual needs and then to build a system based on the results.
Monitoring and control devices integrated into the compressors allow users to choose between five different control modes. They minimise idle time and switching losses, depending on whether a compressor is used to cover base or peak loads.

In larger compressed air stations, higher-level master control systems with management functions such as the new SAM 2 ensure the optimal interplay of individual compressors and perfectly coordinate their operation with the compressed air demand.

Also available: dry-compression rotary screw compressors with variable speed control using a frequency converter. When these systems are used in combination with constant-speed compressors, energy savings of up to 25 percent and more can be achieved.

Analysis yields an optimal set-up

Based on the air demand analysis (ADA) using Kaeser’s proprietary KESS software, the Kaeser compressed air specialists concluded that the ideal system set-up for Christinen-Brunnen was two CSG 130-2 SFC air-cooled, dry-compression rotary screw compressors (7.5 bar) with a two-stage screw compressor block. Each compressor feeds an energy-saving Kaeser SECOTEC TF 173 refrigeration dryer before the dried air is purified in an FE-177 D microfilter and released into the network.

Asked about his new compressed air supply, plant manager Peter Wohlberg is all smiles. And that’s before the excellent energy efficiency of the Kaeser systems is even mentioned. Now it takes just two compressors to match the performance of eight systems from another provider in the previous installation. As Wohlberg explains, that means more than just energy savings when producing and treating compressed air. It has also brought a 75 percent reduction in the maintenance and servicing costs, and has completely eliminated the costs for providing and operating the coolant system for the old water-cooled equipment: The Kaeser compressors are air cooled and require no elaborate additional installations. Moreover, the warm exhaust air is practically recycled. It is used to heat the production halls adjacent to the compressor station, thus saving heating costs.

Peter Wohlberg is confident that the new Kaeser compressed air system will pay for itself in well under two years. That speaks for itself.

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