"We have extreme conditions on site"

Roller energy supply systems for a composting plant
Since the composting plant was commissioned, energy supply systems in various lengths and designs have been in use in the so-called spiral system. The special feature: With heat, coarse dirt and high humidity, the energy supply system has a tough job. Nevertheless, the plant operator expects a service life of 5 years under these extremely aggressive conditions and is highly satisfied after working with the roller energy chain solution from igus®.

Profile

igus® in conversation with the head of maintenance/electrical engineering at AVA Abfallverwertung Augsburg GmbH Dipl.-Ing. Werner Kretzinger

Problem

At the beginning of the 1990s, a facility was built on a 23.5-hectare site in Augsburg, which consisted of a modern composting plant. In the composting plant, quality compost is produced from organic and garden waste and other biodegradable waste. The composting process takes place in the composting hall. With the help of the turning machine, the Wendelin, as the name suggests, the compost is turned so that the "biology "gets to work". Depending on the decomposition phase and degree of rotting, individual conditions are created in the individual windrow sections in terms of biopopulation, metabolism, temperature and moisture. The composting process is completed after around ten weeks, although the conditions on site in the composting plant are extreme. The organic waste rots in a closed hall. Vapour and heat are generated. Temperatures of up to 40 °C and a humidity of almost 100 % are the norm. During operation, the hall should only be entered with a face mask. In addition, there are all kinds of substances in the air that affect the technology. For example, significant concentrations of ammonia and organic acids were found in the air of the rotting hall. Slimy biofilms have formed on all surfaces, including the energy supply lines. The pH values on these surfaces are around pH5. "We can't use steel in the composting hall. Only 316 stainless steel can withstand the conditions on site," says the maintenance manager. The plant runs day and night, so the demands on the durability of the components are extremely high.

Solution

Since the composting plant was commissioned, energy supply systems from igus® in various lengths and designs have been in use in the shifting system, the so-called Wendelin.
The Wendelin has a longitudinal chain and a cross chain in the plant. In addition, there are two further chains in the entry for transporting and distributing the organic waste in the first windrow, which means that a total of eight energy supply systems are in use. Apart from the longitudinal travel, only 'Rol-E Chain' roller energy supply systems from the modular and robust 'E4/4' system are used.
Roller energy chains really come into their own when it comes to long travel distances, high speeds and high cable loads.
In contrast to sliding e-chain®, the necessary drive force can be reduced by 75 %. The coarse and coarsest dirt particles, especially on this system, generally lead to increased abrasion. The even rolling operating mode minimises the rolling resistance and thus the wear of the chain. Their service life increases considerably.
In addition to the roller energy supply systems, chainflex® cables, guide troughs for the long travel distances, separators and strain reliefs from igus® are also used. The unshielded control cable 'chainflex® CF 5' is located in the energy supply system. Thanks to its structure, with a gusset-filling extruded inner jacket and the PVC-outer jacket, the series is suitable for the highest loads.

e-chain® E4/4 system

chainflex® cables

"Although they have been in use for over two years, they have not yet shown any signs of wear. The energy supply systems are checked monthly. Here we can see that no abrasion has been detected so far"

Dipl.-Ing. Werner Kretzinger, Electrical Engineering Maintenance Manager at AVA Abfallverwertung Augsburg GmbH

Continuous development of energy chain systems from igus®

During an initial visit to the operator, igus® presented its roller energy supply system. Developed for particularly dirty applications, among other things, its advantages were quickly recognised at AVA. "And from the first roller chain to the current model, development has not stood still," emphasises Michael Offner. "The distance between the individual rollers has been shortened and once again adapted to the tough conditions on site." Customer requirements have therefore been incorporated directly into product development.
"We immediately ordered a chain for the next revision," recalls Werner Kretzinger. "And were able to compare the two systems. The technical advantages of the roller energy supply system quickly became apparent to us. Today, we only have one sliding energy chain in use, which will be the last to be replaced next year." AVA Augsburg is certain that the roller energy supply systems in the composting plants will last at least five years. This increases the service life fivefold.
"It's a full-time job to keep the energy supply systems running in this atmosphere," concludes the maintenance manager. "But with the monthly measurements and the annual inspections, we realise that we weren't promised too much." The investment pays off.

Rolling instead of gliding

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