Celeroton drives future technologies

Saving energy in compressed air and vacuum applications

Pressurized air is widespread over different industries, and is often a major energy consumer. According to the Umweltbundesamt Deutschland, 17% of the total electrical energy in the industry is used for air compression and there is significant energy saving potential. For vacuum grippers, the vacuum is often generated by pressurized air and a venturi nozzle, called ejector. This principle requires around 2 to 5 times as much energy as direct vacuum generation. Pneumatic actuators and equipment in industrial production lines and manufacturing machines require different pressure levels, ranging from 1 barg up to and beyond the usual 8 barg. Usually, the highest pressure actuator defines the single supply pressure of the entire production line. The other pressure levels are achieved by pressure reduction valves, wasting the pressure difference. In blow molding, 4 to 40 bar blowing pressure is required. The pressure loss over the manifolds, nozzles, and cavity is 0.1 to 1 bar, resulting in an outlet pressure only slightly smaller than the inlet pressure. This outlet pressure is usually blown off and the energy contained within is lost. Similar blowing off strategies are applied in other air compression processes.

Pressurized air contains large amounts of energy, but as shown above, is often not yet considered as valuable as the equivalent of electrical energy. And not as much focus and effort is invested to improve energy efficiency compared to direct electrical energy savings. This will change in the future:

• Operating costs become a decision criterion for selecting and purchasing air compression equipment. There is a shift from invest cost to total-cost-of-ownership decisions.
• Manufacturing and production companies set their own targets on energy efficiency and sustainability.
• Governmental regulations and financial incentives are pushing for a reduction of energy consumption, and compressed air has a significant potential that has not been exploited.

Celeroton’s gas bearing turbo compressor technology allows reducing the compressed air energy consumption in above applications. Turbo compressors can generate vacuum directly, connecting the inlet of the turbo compressor to the gripper. This saves electrical energy compared to ejectors. And there are even further advantages: Due to the small size of turbo compressors vacuum can be generated locally avoiding long pressurized air tubing prone for leaks. A highly dynamic speed control allows for switching vacuum on and off. In an exemplary use case for vacuum gripping of porous materials a conservative calculation shows an energy saving potential of 86%. Meaning 7.5x less electrical energy for the same job!

For this exemplary equipment we consider vacuum grippers with a typical porous material vacuum requirement of 450 mbar (0.55 bara) and total flow requirement of 2000 l/min. The vacuum can be generated by 9 ejectors supplied by a continuously running central industrial air compressor with an average power consumption of 22 kW. Or with direct vacuum generated by a Celeroton turbo compressor CT-2000 with an operating point at pressure ratio 1.8 and 40 g/s, which leads to an input power of around 2.9 kW. 7.5x lower than the central compressor with an ejector solution. This means savings of >32’000 EUR each year (Assumptions: 8500h operation with an energy price of 20 ct/kWh).

Energy saving is also possible in compressed air and vacuum applications, beside vacuum grippers. Industrial production lines can be supplied by a central compressor with a reduced pressure level. According to Unternehmensnetzwerk Klimaschutz this saves 6-10% of the energy for each reduced barg. The equipment with higher pressure requirements within the production line can be supplied from the reduced pressure level by a decentralized, local turbo compressor, providing the required pressure increase from the central compressor pressure level. This even allows for several pressures to be controlled specific for each equipment to further reduce energy consumption. Vice versa, if only limited equipment requires low pressure supply (but potentially high flow), the low-pressure equipment can be supplied by an individual turbo compressor saving energy. In a use case in food industry, a central rotary piston compressor could be unloaded by supplying 0.2 barg locally to a high flow equipment. Additional advantages in this use case beside energy savings are the contamination and oil free air supply due to the gas bearing technology, the low noise which allows local installation close to operators and maintenance free operation.

As the examples show: Celeroton drives future technologies which not only boost the efficiencies in established processes but also enable solutions not feasible with the current state of the art. Reshaping industry standards and drastically reducing the energy demand by doing so. In the future, we expect more company strategies and regulations to request for energy saving strategies and total-cost-of-ownership calculations, also in the field of compressed air for industrial manufacturing. Celeroton prepares for this and plans to demonstrate the energy saving potentials in pilot projects. Interested in joining the demonstration phase or check the energy saving potential in your compressed air or vacuum application? Reach out to us via moc.notorelec@ofni or +41 44 250 52 20.