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ComunicaçãoSocial / Histórias de aplicações / Atlas Copco Centrifugal Compressors Supply Deep Sedimentation Tanks with High-Pressure Air

Atlas Copco Centrifugal Compressors Supply Deep Sedimentation Tanks with High-Pressure Air


Wilrijk, Belgium, June 2014. The sewage treatment plant in Putzhagen, Germany, requires large quantities of high-pressure compressed air for its exceptionally deep sedimentation tanks. Three ZB 130 VSD centrifugal compressors and two older single-stage screw compressors supply the compressed air for the biological process that occurs in the tanks.

ZB 130 VSD centrifugal compressors
Each year, the plant treats an average of between 6.5 and 7 million m3 of sewage water. "The biological process takes place in eight tanks that are sub-divided into four lines," explains Reinhard Schweinforth, Sewage Water Technician. The tanks are 10 m high with a water depth of 8.5 m. "These dimensions are unusual for sewage treatment plants," says Schweinforth. Tanks are normally 4 to 5 meters deep. The biological cleaning processes are carried out in the eight aeration tanks. The air required for this procedure is blown into the tanks from below via diaphragm tube aerators — an energy-intensive process that accounts for 40% of the plant's entire power consumption. 

Wastewater treatment Guetersloh, Germany
An investment in energy efficiency and ease of maintenance
The compressed air required for the biological process was previously provided by five single-stage screw compressors. Because these aging compressors needed to be completely overhauled at great cost, the search for a new energy-efficient solution began. Centrifugal compressors with magnetic bearings were deemed to be the best option because a comparatively high pressure is required for the exceptional depth of the tanks. "We are able to produce higher pressures with the centrifugal compressors than we were previously able to with the screw compressors," explains Schweinforth. "We have purchased the new compressors with the aim that the machines will now be more energy efficient and easy to maintain," says plant manager Karl-Heinz Schröder. "Now that we are using the centrifugal compressors from Atlas Copco, we are saving around EUR 15000 each year on maintenance, energy and resources compared with screw compressors."

Oil-free compressed air as required
The three speed-regulated centrifugal compressors generate between 2500 and 7500 Nm³ of oil-free compressed air per hour depending on the amount of sewage water and the polluting load. The interaction is engineered by the ES 130 master control system from Atlas Copco. The process control system determines the air requirement on the basis of the oxygen content in the tanks. "At the moment, we are still using a constant pressure regulator," says Schröder. "Our next goal is to optimize this regulatory process and integrate a variable pressure regulator. Up to now, we have wasted a lot of energy as we have been operating against closed gate valves at a constant pressure of 1020 millibar. With the variable pressure regulator in place, all eight gate valves are linked and the pressure can be adjusted in line with demand, thereby enabling us to reduce the pressure used."

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Atlas Copco is a world-leading provider of sustainable productivity solutions. The Group serves customers with innovative compressors, vacuum solutions and air treatment systems, construction and mining equipment, power tools and assembly systems. Atlas Copco develops products and services focused on productivity, energy efficiency, safety and ergonomics.  The company was founded in 1873, is based in Stockholm, Sweden, and has a global reach spanning more than 180 countries. In 2013, Atlas Copco had revenues of BSEK 84 (EUR 9.7 billion) and more than 40000 employees.

Atlas Copco’s Compressor Technique business area provides industrial compressors, vacuum solutions, gas and process compressors and expanders, air and gas treatment equipment and air management systems. The business area has a global service network and innovates for sustainable productivity in the manufacturing, oil and gas, and process industries. Principal product development and manufacturing units are located in Belgium, Germany, the United States, China and India.