ZBG Motorentechnik GmbH & Co KG in Bruck, Germany, has managed to drastically cut its energy costs by using VSD compressors and a central controller from Atlas Copco. By eliminating unnecessary idle times and using waste heat for the cleaning baths in production, the company claims to be making a saving of over 115,000 euro every year.
ZBG specializes in highly-automated mass production, with a particular focus on combustion engine components. Numerous pneumatic controllers and handling components in production are driven by compressed air. Robots link up modern CNC machining centers to enable reliable, highly efficient production around the clock. The company saw considerable potential for optimization, especially in the supply of compressed air.
“The idle times in compressed air production were consuming an incredible amount of energy and had to be eliminated. And we wanted to use the waste air from the compressors to heat our component cleaning baths," explainsSiegfried Schmid, Managing Director at ZBG Motorentechnik.
Since the demand for compressed air in production is constantly fluctuating, ZBG decided to install two oil-injected, air-cooled GA 90 VSD screw compressors from Atlas Copco, both with a variable speed drive, as well as a third GA 90 compressor with a fixed speed. The three compressors were linked to an ES 8 central controller. Each of the three machines features a demand-based individual controller, enabling idle times to be completely eliminated and ensuring that all consumers are optimally supplied with the volume flow they need.
The effective energy saving can be seen from the power input: Three times 90 kW gives a peak load of 270 kW. Siegfried Schmid explains:
“Because the two VSD machines work primarily in the partial load range, only around 150 kW are required on average to generate the compressed air supply. And what's more, we can use this again as heat energy".
To achieve the second goal, ZBG uses the heat recovery systems in the compressors. The coolant, at 90°C, can bring the cleaning baths up to temperature via the heat exchangers. Consequently, ZBG Motorentechnik was not only able to deactivate the entire electrical heating system for the baths, but could also heat their offices — appreciably reducing natural gas consumption too.
The company saves approx. 115,000 euro a year in electricity costs alone.