More safety with energy chains in the Nice wastewater treatment plant

Profile

• What was needed: E2 family chains, guide trough made of 316 stainless steel, chainflex cables with TPE outer jacket, floating moving end made of 316 stainless steel
• Requirements: Heavy load due to continuous operation of the plant, highly corrosive environmental conditions
• Industry: Sewage plant
• Success for the customer: Maintenance-free energy supply system with long service life

Problem

The wastewater plant, which was built in 1988 on a site of 3.5 hectares, contains numerous innovations. It is responsible for the wastewater of the approximately 500,000 inhabitants of the cities of Nice, Saint-Jean-Cap-Ferrat, Beaulieu and Villefranche-sur-Mer. There, 10 sedimentation tanks with an area of 10 x 25 metres each are operated for preliminary treatment, as well as 12 secondary sedimentation tanks with an area of 12 x 60 metres each. A total of 45 people work on the site, including 15 in eight-hour shifts. The plant is operated all year round. Mistakes are not allowed, because all the beaches in the area have the "Pavillon Bleu", the mark of clear bathing water certification. The water leaving the treatment plant is therefore subject to very strict standards.
For the electrical supply of the 10 bridges of the 25-metre sedimentation tanks and the 12 bridges of the 60-metre secondary sedimentation tanks, a classic loop system was initially used for the energy supply, in which the flat cables were attached to ball-bearing carriages and moved back and forth on a fixed rail. The first carriage was connected to the bridge and the whole thing followed the movements of the bridge. Because of the difficult environmental conditions and the constant work of the bridges, Jean Camilla had to service the carriages of all the basins on a monthly basis. This work, which was costly in terms of time and manpower, also led to costly management of spare parts and frequent interruptions in the processes.

Solution

Therefore, the technical arguments and the advantages of the readychain solutions proposed by igus for the energy supply of the total of 22 bridges appealed to the operators in particular. The standard chains of the E2 family are made of plastic and therefore insensitive to corrosion. They have a long service life and are maintenance-free.  The first readychain system from igus was tested in operation on site for a year before the decision was made to equip all HALIOTIS basins with energy supply systems from igus after the successful test run.
The solution also consists of a guide channel made of 316 stainless steel with an open base to facilitate cleaning, and mounting brackets also made of 316 stainless steel, whose design allows compensation for misalignments of the building infrastructure and quick installation on site.
The various cables in the e-chain are well protected, the movements are fluid and a lot of space has been saved. With the highly flexible chainflex cables, which are specifically designed for use in energy chains, millions of work cycles can be carried out without maintenance. Cables with TPE outer jackets were provided for the sewage treatment plant; these are particularly suitable for dynamic applications and are resistant to oil and dirt. For reliable operation of the system, the floating moving end was also made of corrosion-free steel. This part, specifically designed by the igus design office, compensates for the slight misalignments of the rails during the movements of the bridge.