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Evolution in pneumatic conveying technology Advantages of magnetic bearing turbo compressors in the pneumatic con- veying of bulk solids INGO BARTZ, DETLEF LOBAS „PILLAERATOR GMBH” The optimal handling of bulk solids usually requires a lot of process know-how and experience in plant engineering. For example, when transporting bulk materials, pneumatic conveying systems are used, the design and construction of which involves enormous expertise in order to ensure smooth and long-term operation. The main purpose of the design is to match the required plant capacity to the bulk material properties and to select the required silo volumes, pipe cross sections, locks and conveying air compressors in order to develop a plant that optimally operates from the point of view of process engineering. Once the plant has been erected and put into operation, due to its compactness and function-required geometries, it is hardly possible to make any subsequent changes. The engineering of a pneumatic conveyor system must therefore be relieable from the start of the project in order to be able to guarantee trouble-free operation at all times, thus guaranteeing optimal performance. Fig1: Evolution in pneumatic conveyor technology. In energy-efficient, pneumatic conveying systems, modern magnetic bearing turbo compressors pre- vail over the obsolete technique of positive dis- placement machines. Among these aspects, the cost-effectiveness has to be con- sidered, in which the investment costs play a significant role and are well comparable. However, the operating costs should be considered as a main factor for an economic plan- ning. These are essentially the energy and maintenance costs, which can hardly be reduced after final commission- ing. When comparing the life cycle cost of a plant, beside the investment costs the maintenance and energy costs for a defined period of time, quickly becomes important. It is apparent that the use of conventional displacement ma- chines (Roots or Screw Blowers) for pneumatic conveying is less efficient and a payback of slightly higher investment costs for more efficient magnetic bearing turbo compressors will be achieved in a short time. In particular, the energy costs have increasingly a significant impact on the total manufacturing costs and thus on the price of the manufactured products and thus on the profit and competitiveness of the operator. Finally yet importantly, energy consumption also determines the carbon footprint and energy savings help to improve the product image and save the nature. For both companies using pneumatic conveying and plant engineering, it is therefore essential to think about the right choice of components in terms of energy efficiency and maintenance intensity already in the planning phase. The core components of each pneumatic conveyor system are the blowers and compressors. Depending on the system ca- pacity roots blower, screw compressors, turbo compres- sors, etc. can be installed as conveyor air generator with the required outputs. Since these make up the essential energy and maintenance costs of each conveyor system, special care is required in this selection. Turbo compressors have a much better efficiency than con- ventional positive displacement blowers (e.g. roots or screw compressors) due to their principle of operation. Therefore, not only is the specific energy consumption of turbo com- pressors considerably lower than that of conventional dis- placement blowers, but also the compression temperature. If the conveying air temperature plays a major role, for ex- ample, in the case of food or plastics, the use of heat ex-

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Evolution in pneumatic conveying technology

Advantages of magnetic bearing turbo compressors in the pneumatic con-veying of bulk solids INGO BARTZ, DETLEF LOBAS „PILLAERATOR GMBH”

The optimal handling of bulk solids usually requires a lot of process know-how and experience in plant engineering. For example, when transporting bulk materials, pneumatic conveying systems are used, the design and construction of which involves enormous expertise in order to ensure smooth and long-term operation. The main purpose of the design is to match the required plant capacity to the bulk material properties and to select the required silo volumes, pipe cross sections, locks and conveying air compressors in order to develop a plant that optimally operates from the point of view of process engineering. Once the plant has been erected and put into operation, due to its compactness and function-required geometries, it is hardly possible to make any subsequent changes. The engineering of a pneumatic conveyor system must therefore be relieable from the start of the project in order to be able to guarantee trouble-free operation at all times, thus guaranteeing optimal performance.

Fig1: Evolution in pneumatic conveyor technology. In energy-efficient, pneumatic conveying systems, modern magnetic bearing turbo compressors pre-vail over the obsolete technique of positive dis-placement machines.

Among these aspects, the cost-effectiveness has to be con-sidered, in which the investment costs play a significant role and are well comparable. However, the operating costs should be considered as a main factor for an economic plan-ning. These are essentially the energy and maintenance costs, which can hardly be reduced after final commission-ing. When comparing the life cycle cost of a plant, beside the investment costs the maintenance and energy costs for a defined period of time, quickly becomes important. It is apparent that the use of conventional displacement ma-chines (Roots or Screw Blowers) for pneumatic conveying is less efficient and a payback of slightly higher investment costs for more efficient magnetic bearing turbo compressors will be achieved in a short time.

In particular, the energy costs have increasingly a significant impact on the total manufacturing costs and thus on the price of the manufactured products and thus on the profit and competitiveness of the operator. Finally yet importantly,

energy consumption also determines the carbon footprint and energy savings help to improve the product image and save the nature.

For both companies using pneumatic conveying and plant engineering, it is therefore essential to think about the right choice of components in terms of energy efficiency and maintenance intensity already in the planning phase. The core components of each pneumatic conveyor system are the blowers and compressors. Depending on the system ca-pacity roots blower, screw compressors, turbo compres-sors, etc. can be installed as conveyor air generator with the required outputs. Since these make up the essential energy and maintenance costs of each conveyor system, special care is required in this selection.

Turbo compressors have a much better efficiency than con-ventional positive displacement blowers (e.g. roots or screw compressors) due to their principle of operation. Therefore, not only is the specific energy consumption of turbo com-pressors considerably lower than that of conventional dis-placement blowers, but also the compression temperature. If the conveying air temperature plays a major role, for ex-ample, in the case of food or plastics, the use of heat ex-

changers is required, turbo compressors delivers ad-vantages at the process air outlets with a lower temperature level due to the higher efficiency of compression, addition-ally this pays off in savings on the periphery.

A combination of high-efficiency turbo technology and non-contact magnetic bearing alone represents the optimum and lowers operating costs through the lowest specific en-ergy requirements. By a control, which keeps the delivered mass flow and the flow velocity in the pipe permanently constant, with changing suction conditions due seasonal condition, the energy requirement for the conveying air is reduced to a thermodynamic minimum. The mass flow com-pensation in the event of seasonal fluctuations in tempera-ture and humidity occurs automatically with the magnetic bearing turbo compressor due to the no-fault control. Con-ventional positive displacement machines have so far only been designed for the maximum required delivery volume and run unregulated all year round on a high energy con-sumption. In addition to the inherent energy savings of about 20% of magnetic bearing turbo compressors com-pared to positive displacement machines, in the case of this seasonal changes in pneumatic conveying a saving of en-ergy of a further 10% can be achieved. Energy saving of over 30% compared to the use of conventional compressors can ultimately be achieved with magnetic bearing turbo compressors in total.

Fig2: Magnetic bearing turbo motor with directly

mounted impeller

In addition, a magnetic bearing turbo compressor offers wear- and maintenance-free operation. Costly maintenance work, in which rolling bearings, sealing elements and drive

belts have to be replaced, is therefore superfluous. Produc-tion losses are avoided or reduced to a minimum because maintenance-free shut-off of the drive unit of magnetic bear-ing turbo compressors is the exception and not the rule, as is the case with roots or screw blowers. Oils or other lubri-cants are not used in magnetic bearing technology, so there is no risk of contamination and safety is guaranteed all times. Elaborate and again maintenance-intensive and fail-ure prone oil separations can be completely dispensed for magnetic bearing turbo compressors. If there is no oil in, it can not leak out. Another advantage of magnetically levi-tated turbo compressors is their low noise emission and the complete absence of vibrations, which is another aspect for the planning and design of a plant for operators of conveyor systems near residential areas.

The company PillAerator GmbH develops and manufac-tures magnetic bearing turbo compressors for pneumatic conveying, as well as for other applications where efficient process air with high availability is required. The promotion of nitrogen and some other gases is also possible. Drive motor and compressor stage are connected to each other via a flange, compressor impeller and motor shaft form a common unit. PillAerator turbo compressors completely dis-pense with conventional and maintenance-intensive drive components such as belt drives, gears, synchronous and gearbox transmissions. The maintenance of these tur-bomachinery consists mainly of changing the intake filters, which maximizes uptime and keeps maintenance costs ex-tremely low. Integration into process control systems is pos-sible at any time without any problems, as a Siemens S7 industry standard is used in the PillAerator. A mass flow compensation, which holds both process air charge and pipe flow constant at minimum power consumption con-stant, is already integrated as a rule criterion in the control. Operators of pneumatic conveyors are advised to look at their operating costs in terms of reducing their existing en-ergy requirements and maintenance costs, and to have them retrofitted with PillAerator GmbH magnetic bearing turbo compressors for a potential reduction in operating costs. The experts of the PillAerator GmbH are at always at your disposal for a non-binding consultation.

[1] DIRECTIVE 2012/27/EU OF THE EUROPEAN PARLIA-MENT AND OF THE COUNCIL of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC

[2] Germany makes it efficient, BMWI, National Action Plan on Energy Efficiency

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