Friday, August 3, 2018
Increase energy efficiency
90 to 95 per cent of energy expended is transformed into heat in the compression process.
Plant engineers are continuously developing their systems. New options are opening up for established customers too thanks to the evolution of technologies. Audits are a good opportunity to obtain an overview of individual optimisation potentials. Manufacturers such as BOGE visit users on-site, track the systems, identify possible deficits using the data and work out proposals for improvement. Central to this is the topic of energy efficiency. How can waste heat be made usable? Can the amount of air produced be further optimised? And what measures increase the efficiency of compressed air treatment?
System audits are studies of customer systems with the objective of uncovering potential for improvement. For compressors, options should be pointed out among other things, as to how the same amount of compressed air in cubic metres can be generated with lower energy consumption. “To record the current status of a compressed air station, we install a measuring kit at the customer’s premises, which records the compressed air circumstances and controls there for two weeks. Our specialists then derive optimisation potential from the data obtained", explains Frank Hilbrink, product manager at BOGE. “This could be hardware or software updates but new acquisitions may be worthwhile.” The Federal Office of Economics and Export Control (BAFA) funds the acquisition of new energy-efficient compressors by 20 to 30 per cent. To find out whether an update or upgrade makes more sense for a compressed air station, a study is made from four perspectives: the opportunities to make waste heat usable, integrating higher-level controls, varying the frequencies (speeds) of individual machines and making the treatment of compressed air more efficient.
The production of compressed air is a very heat-intensive process. 90 to 95 per cent of the energy expended is transformed into heat in the compression process, so that only a small proportion of the energy provisionally remains in the compressed air. There are two options for making the lost energy usable for other processes in the company: the direct use of heat for heating purposes as well as decoupling the heat from the oil circulation to heat up water. Heated up water is suitable for process water as well as for service water in sanitary facilities within the factory. With DUOTHERM, BOGE has developed a heat recovery system for decoupling heat from the oil circulation. “As a plate heat exchanger, DUOTHERM is a standard solution for oil-lubricated screw compressors. If an audit shows that a great deal of heat is being lost in the process of producing compressed air, it is advisable to integrate this product”, explains Hilbrink. DUOTHERM is a compact system of several metal plates operated in parallel. On one side of the plates is the hot oil and on the other side is the water that is to be heated up. The heat is transferred from one medium to the other via the thin metal sheet. Compressed air stations can be retrofitted with DUOTHERM, or it can be supplied directly with the pre-integrated system.
Optimising the delivery volume – lowering energy consumption
A compressed air station usually consists of several compressors. If there is no higher-level control available, there is the risk that the machines will affect each other through their controls. To prevent this, where there are three compressors, the first compressor would have to be set precisely to the required pressure, but number 3 would have to be set up to two bars higher. Over-compression of two bar corresponds to energy consumption that is ten to twelve per cent higher than actually required. Audits can display options here as to how users can achieve a compressed air level that is precisely tailored to the requirements in question. Compressors can therefore be switched on and off intelligently with a higher-level control thanks to a separate pressure sensor. Control of the gaps between the compressors thereby becomes obsolete. The result: the pressure is approximately at the level the user requires. However, to achieve the required pressure level precisely, a combined compressed air station consisting of compressors with fixed and variable speed is required. The systems often have a fixed speed, which is why they do not have to achieve the required pressure precisely. This can be altered with the integration into the station of a frequency-controlled machine with variable speed. “By using frequency-controlled compressors, the exact amount of compressed air that a user requires can be produced. Overcompensation is thereby prevented”, explains Hilbrink. “In conjunction with modern higher-level controls such as our airtelligence provis 2.0 and airtelligence plus, a combined compressed air station is created with the highest level of efficiency.”
Treating compressed air efficiently
Dust, corrosion, oil and condensate are constant threats to the quality of compressed air. With food applications there is also the risk that oil will cause contamination of the air. Filters and dryers therefore have to be used in compressed air treatment. In the first stage, dust particles are filtered along with moisture from the air, then oil and condensate can be dried out of the air if necessary. Such treatment tools are also available in older stations, however, they often perform too poorly when it comes to energy efficiency. An audit gives information about whether the installation of a new filter or dryer would be worthwhile for a user. “Our solutions can be easily integrated into existing machinery”, says Hilbrink. “We observe time and again that customers are very surprised about the savings potential that exists in a compressed air station. As we are constantly optimising our products, audits are also to be recommended for users with new systems.”
The heat that is produced when generating compressed air can be used for heating purposes, for example – such as is the case here at the BOGE headquarters in Bielefeld.
With the help of the airtelligence provis 2.0, higher-level control, BOGE helps compressed air stations consisting of several systems to achieve higher efficiency.
As one of Germany’s oldest manufacturers of compressors and compressed air systems, BOGE KOMPRESSOREN Otto Boge GmbH & Co. KG offers more than 100 years’ experience. The company is also one of the market leaders. Whether for High Speed Turbo compressors, screw compressors, piston compressors, scroll compressors, complete systems or individual devices, BOGE meets the most diverse requirements and highest standards, with precision and quality always at the forefront. The family company which operates internationally has a workforce of 850 employees, approximately 490 of whom work at the headquarters in Bielefeld, and is managed by Wolf D. Meier-Scheuven and Thorsten Meier. With its numerous sales offices and subsidiaries, BOGE offers its international customers comprehensive services and supplies its products and systems to more than 120 countries worldwide.
Ina Rockmann • BOGE KOMPRESSOREN Otto Boge GmbH & Co. KG
Otto-Boge-Straße 1–7 • 33739 Bielefeld
Phone: +49 05206 601-5830