Atlas Copco’s new compressor concept saves tire manufacturer around EUR 300 000 a year
June 26, 2015
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EuropeAt the Michelin plant in Homburg, Germany, an oil-free variable speed drive ZR air compressor from Atlas Copco is at the core of a new compressor concept that has already saved the company a six-figure sum in energy costs over the first year. The system functions so efficiently that the specific energy requirement for the compressed air supply fell from 0.143 to 0.108 kWh per standard cubic meter.
ZR315VSD compressor at Michelin
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Seven compressors are available, which can feed compressed air into two pipe networks, each of which provides air of a different quality. One network supplies cold air at 3°C as industrial air, while the other network supplies control air, which must be completely dry and is therefore cooled to –28°C. “This air is used in the laboratory and for sensitive units,” explains Winfried Schäfer, Technical Manager at Michelin. If the four turbo and three screw compressors ran at the same time, they could produce around 18 400 standard cubic meters of compressed air per hour. Current average demand is only 10 000 Nm 3/h. Redundancy ensures that production can continue around the clock, even if one or more compressors were to fail.Speed regulation and master control system save energy costs
Some time ago, the company attempted to implement retroactive regulation of the turbo compressors (which were only able to run at full load), so that the compressed air supply could be better adapted to demand. A 20% success rate was achieved with this system of turbo regulation – although the compressors no longer worked so efficiently. It was established that the existing compressors and their manufacturer were unable to deliver a satisfactory solution, and a master control system and an oil-free ZR 315 VSD FF screw compressor supplied by Atlas Copco now form the core of a new compressed air concept. In the designation ZR 315 VSD FF, “VSD” stands for “Variable Speed Drive”, the number 315 refers to the installed power in kilowatts, and the “FF” is for “Full-Feature”: full specification with integrated adsorption dryer. The ZR 315 VSD FF works at a variable, regulated speed. Thus, instead of constantly generating more than the required amount of compressed air, the exact quantity required can now be produced. According to Schäfer: “We never look for the cheapest or quickest solution, but always the most reliable – and it must be efficient.”System runs 25% more efficiently
The solution with the master control system and the new compressor has already provided significant savings: the specific energy demand was previously 0.143 kWh per standard cubic meter, but now reaches an average of 0.108 kWh. “This means the system now runs almost 25 percent more efficiently,” reports Winfried Schäfer. “Four compressors are usually in operation at the same time – three turbo compressors and the Atlas Copco VSD compressor, which adjusts to supplement the ‘missing’ air up to the target pressure of 7.0 bar and compensates for pressure fluctuations.”Michelin Tire assembly