The world's largest polymer energy chain

The port of Antwerp is the largest port in Belgium. In 2011 alone, more than 187 million tonnes of freight were handled. To ensure that the huge container ships, among others, can unload their cargo without any problems, the shipping lanes must always be clear. To this end, the shipping lanes are dredged and expanded using special vehicles. As the space available for storing the dredged sediment continued to shrink over time, the port authority and the Flemish government decided to invest in a modern sludge dewatering system as part of the ambitious "AMORAS" (Antwerp Mechanical Dewatering, Recycling and Application of Sludge) project.

The coarsely sorted sediments - around 500,000 tonnes per year - are now pumped through a pressure pipeline to the plant 4 km away, where they are mechanically dewatered, processed in an environmentally friendly manner and then stored. The central component of the silt processing plant is an imposing arch-shaped bridge with a span of around 180 metres. Two movable, independently operating high-performance pumps are attached to the bridge, which can be rotated through 360°. The dredger pumps suck around 600 m3 of sediment or silt per hour from the settling basin below and transport it via enormous hoses with a diameter of 300 mm for further processing. A robust solution had to be found for the energy supply to the pumps that could cope with the dimensions of the project. All central components of the huge system had to be designed for a minimum service life of 15 years. But the requirement profile goes even further. The dewatering system is in use almost continuously 365 days a year. Operational safety comes first. There must be no unnecessary maintenance and downtimes.

Today, an extremely robust polymer chain from igus® GmbH, Cologne, is used to safely guide the system's hoses throughout the entire journey. This is the maintenance-free model E4.350 from the particularly robust E4.1 series, which can be opened on both sides and has proven itself in countless applications. It demonstrates its versatility in composting and sewage treatment plants, tool and construction machinery, crane technology and wood processing, among others.

With an inner height of 350 mm and an inner width of up to 800 mm, the E4.350 is the largest plastic energy chain in the world to date. For use in the most demanding "Heavy Duty" applications, it can easily handle heavy and, if necessary, stiff loads and is highly wear-resistant, corrosion-free and resistant to oil and seawater. In order to minimise rolling resistance, sliding rollers made of the tribo-optimised plain bearing material iglidur®, which demonstrates its strength in a wide range of applications, prove their worth as a special design on the opening webs. The friction of the hose in the chain is significantly reduced, thus guaranteeing stability.

In addition to the energy supply system, a corrosion-resistant guide trough and floating moving end are used. They are used to compensate for any lateral offset tolerances. The energy chain, which is filled with hose and cable, is always safely guided along its entire length in all weathers. Despite the difficult operating and environmental conditions, there have been no failures to date.
To ensure the operational safety of the bridge construction, the plant manufacturer also decided to invest in an electronic monitoring unit. The Push/Pull Detection System diagnostic tool (Push Pull Force Detection System), which has proven its worth particularly on long travel distances, measures the push/pull forces of the energy chain online every four seconds and compares them with a calculated target value. In the event of malfunctions, the system can be stopped automatically with the help of the diagnostic tool to prevent damage.

The decision in favour of the comparatively lightweight plastic energy supply system was quickly made. Both companies worked together in a spirit of trust from day one of the engineering process. On the one hand, this applies to the complex design process of the bridge construction. A large number of design drawings were made available in an uncomplicated manner depending on the status of the project. On the other hand, the extensive laboratory tests that took place in advance were also convincing. "The sustained support provided for this major project led to success," says Joury van Gijseghem. "Together, we managed this project from the first to the last day." 
The plant manufacturer also drew on its expertise in assembly. The specialist for energy supply systems built the entire system, which was installed on site on schedule by the company's own employees. The system has been running smoothly from day one. "We have never regretted our decision in favour of the plastic energy supply system," concludes Joury van Gijseghem. "It also paid off for us to involve the system supplier in the project right from the start. This allowed us to minimise errors right from the start."