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Saving Energy with Compressed Air

Concrete Measures For Enormous Energy Saving Potential

Mar. 16, 2011
100% of a compressor's electrical energy consumption is converted into heat. With fluid-cooled rotary screw compressors, up to 96% of that energy can be recovered and reused. Perhaps surprisingly, the usable energy in compressed air actually comes from the ambient surroundings: During the compression process and conversion of the electrical drive energy into heat, the compressor charges the air it draws in with energy potential corresponding to approximately 25% of the compressor's electrical power consumption. This energy is only usable however once the compressed air expands at its point of use and in so doing absorbs heat energy from the surrounding environment.
100% of a compressor's electrical energy consumption is converted into heat. With fluid-cooled ... more

Saving Energy - Today's technology offers compressed air users myriad ways to significantly reduce energy consumption and CO2 emissions. It has long been recognized that energy consumption accounts for the lion's share of compressed air costs, and this was already a subject of considerable discussion within the compressed air sector around the time of the first oil crisis in the early 1970s. During that period, rotary screw compressors were starting their ascendance as the technology of choice for industrial compressed air production.

Spotting this trend early on, Kaeser Kompressoren not only added rotary screw compressors to its extensive product range, but went on to develop its proprietary energy saving "Sigma Profile" screw airend rotors. "More air, more savings..." was already the slogan even back then. However, the topic of energy efficiency only came back to the forefront at the end of the '90s with the signing of the Kyoto Protocol. At about the same time, the EU launched the "Save II" initiative. A study carried out within the framework of this initiative gave rise to the "Druckluft effizient" (Efficient Compressed Air) campaign, which was a collaborative project between the VDMA (German Engineering Federation), Fraunhofer ISI, the German Energy Agency (Dena) and businesses from the compressed air sector.

Over 30% Energy Saving Potential

The study determined that compressed air systems in Europe had an average energy saving potentialof nearly 33%. This finding was further consolidated by compressed air audits carried out as part of another measurement program; the audits revealed potential energy savings for the companies studied of between 18- 70%, depending on circumstance. So, in spite of some improvements, many companies' compressed air installations are more akin to those from the 1970s than to today's energy efficient systems.

Electrical Drives With Enhanced Performance

In the last few years, it has been possible to develop electric motors that operate at unprecedented levels of efficiency. In order to unify the various energy efficiency standards for asynchronous motors from around the world as a globalized standard, the International Electrotechnical Commission (IEC) created the IEC 60034-30 international norm.

It defines the efficiency classes IE1 to IE3, with IE3 being the highest class. In Europe, motors complying with this premium efficiency class will be obligatory for drives from 7.5 - 375 kW as from Jan.1 , 2015. Kaeser, however, already began installing IE3 motors in its new rotary screw compressors in 2010, and the rest of the product range will follow suit in a gradual roll out.

Energy Saving Compressors

Modern compressors are prime examples of highly developed mechatronic systems. Consequently, their efficiency is not only determined by optimum interplay between mechanical and thermodynamic components, but also between electrical and electronic components. Power transmission too plays a key role: Modern direct drive systems eliminate the transmission losses associated with gear or belt driven systems as the drive motor and compressor airend rotate at the exactly the same speed. The energy efficiency of the airend itself can also be increased further through optimization of the screw rotor profile and ancillary equipment for cooling, as well as through minimization of internal pressure losses.

Flexible Internal Compressor Control

A further important efficiency enhancing component is the compressor's internal controller. In the past, these systems often only had one control mode, yet modern industrial PC-based systems offer up to five pre-programmed options, thereby enabling compressor performance to be precisely matched to suit compressed air demand.

Kaeser's new Sigma Control 2 controller also offers added advantages: This advanced system provides greater flexibility through its numerous interfaces and innovative plug-in communication modules. Therefore, connection to energy-saving master control systems, computer networks and/or remote diagnostics and monitoring systems, such as Kaeser's Teleservice facility, couldn't be easier. The large display located on the control panel also simplifies on-site communication with the system, whilst the addition of an RFID reader ensures service continuity, increases security and significantly raises service quality.

High Service Quality

Moreover, these controllers provide an excellent basis for planned preventive maintenance resulting from continuous monitoring of compressor status and even the compressed air filters. This is essential for any comprehensive service concept that strives to ensure best possible dependability and availability, as well as optimized energy and maintenance costs. Needless to say, service should not be restricted solely to the compressors and other components, but should extend to cover the compressed air system as a whole.

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Keywords : CO2 emissions compressed air compressed air audits compressed air drying compressed air production compressor heat compressors dena energy consumption reduction Energy efficiency energy efficient compressed air drying Fraunhofer ISI German Energy Agency German Engineering Federation highly developed mechatronic systems IEC IEC 60034-30 internal controller in compressors International Electrotechnical Commission Kaeser Kompressoren Kaeser’s Air Demand Analysis Kaeser’s Energy Saving System Kyoto Protocol preventive maintenance preventive maintenance air compressors recyclable compressor heat reducing co2 emissions rotary screw compressors SAM Save II initiative Sigma Air Manager Sigma Control 2 Kaeser VDMA

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