Reimann & Rößle uses three C 9 D type Boge screw compressors in up to three production shifts per day. To avoid expensive idle times during compressed air production, the company invested in an airtelligence plus compressor control. Compressed air generation can now be controlled in an intelligent and consumption-based way, reducing energy use during production sustainably and easily.
The author: Gunnar Heise Product Market Manager, Boge Compressors
The three screw compressors with identical performance data change between base, medium and peak load in a 24-hour cycle. The peak rate of currently about 3 m³/min is only needed for a few hours per day. Compressor efficiency amounts to 94 % on average. This efficiency, which is extraordinarily high for screw compressors without frequency inverters, is possible thanks to competent planning of the compressor station in combination with airtelligence plus, Boge’s intelligent control system.
On-demand compressed air generation
“The airtelligence plus multiple control system ensures that the compressed air we continually need is generated as efficiently as possible – without idle times or losses”, explains Dieter Reimann, Managing Director of Reimann & Rößle. The 4” colour display for intuitive operation of airtelligence plus indicates the status of the three compressors: in addition to the current system pressure, the operating conditions of individual compressors can be viewed. Moreover, the display provides information showing which of the two individually set pressure ranges is activated and when the next compressor change is scheduled du-ring base load supply.
Since Reimann & Rößle already had Boge compressors in use, the airtelligence plus higher-level control system was easy to install: the three C 9 D screw compressors simply communicate by the standard bus system (RS 485/Modbus). For older machine controls, Boge offers interface modules that allow the compressors to be integrated.
As the compressor station at Reimann & Rößle consists of three units of identical size, the company could also have selected an internal compressor control featuring traditional base-load rotation operation. Usually, however, this depends exclusively on the user-defined pres-sure switching points. Furthermore, control by an internal compressor control system – and hence the system pressure sensor of one compressor defined as master – poses a risk of dynamic and differential pressures in the compressed air line or the compressed air treatment unit. Thanks to the target zone regulation of the airtelligence plus and the external system pressure sensor, significant optimi-sation of the whole compressor station can be achieved along with a substantial reduction in idle times, load changes and motor starts. “Our production staff can programme the control system in such a way that previously defined compressors are activated or deactivated according to consumer profiles. As a result, prod-uction can ensure that the compressors active at any given time are those that generate the required compressed air rates in the most eco-nomical way”, Reimann continues. If only a small volume flow is required to cope with fluctuating demand, the control system will activate only one or two compressors. However, if the peak rate of currently approx. 3 m³/min is needed, all three compressors are activated.
Savings guaranteed
The marked increase in efficiency achieved with airtelligence plus results in two direct benefits for users: energy costs drop, although the compressed air rate supplied remains constant. Maintenance costs are also lower – because airtelligence plus makes sure the individual compressors always work at their optimal operating points.
Additional cost savings are achieved through heat recovery: Reimann & Rößle uses the waste heat from the compressors via exhaust air ducts to heat the storage and production areas in the winter months. The investment in a new compressed air supply system with heat recovery, coupled with the airtelligence plus intelligent compressor control, has helped Rei- mann & Rößle reduce the costs for electric power and hence CO2 emissions.
Hall 26, Booth B48
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