"We have extreme conditions on site"

Profile

• What was needed: Roller energy chain 'E4/4', chainflex cables (including "chainflex CF 5"), guide troughs, separators, strain relief elements
• Requirements: High temperatures and humidity in the plant, high ammonia concentration, slimy biofilms on surfaces, high risk of corrosion
• Industry: Composting
• Success for the customer: Considerably longer service life of the energy supply system with five times longer service life compared to gliding e-chains

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 created on a site of 23.5 ha in Augsburg, which partly 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 layer rearranging machine, the Wendelin, as the German name suggests, the compost is shifted so that the "biology gets to work". Depending on the decomposition phase and the degree of rotting, individual conditions arise in the individual heap sections with regard to bio-population, metabolism, temperature and moisture. After about ten weeks, the composting process is complete, but the conditions on site at the composting plant are extreme. The organic waste decomposes in a closed hall. Steam and heat are generated. Temperatures up to 40 °C and a humidity close to 100 % are the rule. During operation, people should only enter the hall with a face mask.  In addition, there are all potential substances in the air that affect the technology. Thus, significant concentrations of ammonia and organic acids were found in the air of the composting hall. Slimy bio-films have formed on all surfaces including the energy supply lines. The pH values on these surfaces are around pH5. "We cannot use steel in the composting hall. Only 316 stainless steel can withstand the conditions on site," says the maintenance manager.  The system runs day and night, so the durability requirements of the components are extremely high.

Solution

Since the commissioning of the composting plant, energy supply systems from igus in various lengths and designs have been in use in the layer rearrangement unit, the so-called Wendelin.
The Wendelin has a longitudinal chain and a transverse chain in the system. In addition, there are two more chains at the input for conveying and distributing the bio-waste in the first heap, making a total of eight energy supply systems in operation. Apart from the longitudinal travel, only 'rol e-chain' roller energy supply systems of the modular and robust E4/4 system are used.
Roller energy chains display their full strength with long travels, high speeds as well as high cable loads.
In contrast to gliding e-chains, the necessary drive forces can be reduced by 75 %. The coarse and coarsest dirt particles especially on this unit usually lead to increased abrasion. In the evenly rolling operating mode, the rolling resistance and thus the wear of the chain are minimised. Their service life increases considerably.
Their service life increases considerably. In addition to the roller energy supply systems, chainflex cables, guide troughs for the long travels as well as separators and strain relief elements from igus are also in use. The unshielded control cables 'chainflex CF 5' are located in the energy supply system. Due to its construction, with gusset-filling extruded inner jacket and the PVC outer jacket, the series is suitable for the highest stresses.