Increasing process reliability, minimising maintenance effort, transmitting data in a sustainable manner - these are the requirements for the energy supply of the sand trap scraper in the sewage treatment plant in Bamberg. A reliable energy chain system from igus ensures the necessary functional safety. It replaces an aging motor cable drum. The cost-effective and low-maintenance complete system consists of a robust energy chain, various cables for power and data transmission as well as an enclosure made of stainless steel. All those involved are certain: the maintenance-free system will function trouble-free for many years.
The Bamberg mechanical-biological sewage treatment plant with nutrient elimination is designed for around 220,000 inhabitants. Here, between 95 and 99 percent of the substances contained in the wastewater are removed before discharge into the Regnitz. With a total of 29 employees, the tasks are carried out by the process engineering department, an electrical and metalwork workshop and the wastewater laboratory.
In the sand trap scraper area, an aging solution with an automatically winding and unwinding motor cable drum for power and data supply needs to be replaced. On the one hand, this original setup no longer met the increasing technical requirements in the area of complex data transmission. The new solution has to prove itself in the plant under continuous load, as the sand scraper is in operation round the clock, 365 days a year. At the same time, there are strong weathering effects that have already severely damaged the old system. Since the motor cable drum finally gave up the ghost during the project planning phase, the new energy supply solution also had to be implemented within just a few months.
Today, a standardised basic flizz system is used to supply energy, data and air, which has proven itself for years in many sewage treatment plants throughout Europe. The low-maintenance system covers travels of up to 100 metres and more. Modular in design, it combines the energy chain, and guide trough in the sewage treatment plant in a compact, weatherproof complete solution encased in stainless steel, which defies weathering effects such as sun, wind, snow and ice and functions reliably under continuous load.
In addition to chainflex electrical cables for the pumps and the motor, chainflex special cables with TPE outer jacket for outdoor use are also available in the energy chain for data transmission. Most of them were assembled on site by the specialists or inserted into the chain. A Condition Monitoring System for additional push/pull force detection also provides the necessary system protection in the plant today. If the set value is exceeded or falls short, the system switches off automatically. In this way, cost-intensive disruptions are prevented in advance. A floating moving end, attached to the moving end arm, compensates for transverse movements or lateral displacement of the scraper and ensures force-free running of the chain in the guide trough.
Since the installation in 2000, the system has been running without any problems. The maintenance effort could thus be drastically reduced. It is therefore not surprising that the Aggerverband is satisfied with this solution. Those responsible also give good marks to the service provided by igus. Reinhard Braun, Head of the Electrical Engineering Division of the Aggerverband, says: "Our contacts have always been quick and unbureaucratic in their response. "
It is not only in this application that the lbt flizz system proves itself under adverse environmental conditions. All materials used in the system are corrosion-protected and weather-resistant. Accordingly, many other possibilities have already been implemented, for example in rainwater overflow basins or even in harbour cranes, which have to meet extreme requirements in terms of corrosion protection. Since the system components are also resistant to common chemicals, greases and solvents, igus also supplies the lbt flizz system to manufacturers and operators of galvanising plants and other chemical engineering plants.
On the motor drum that previously supplied the sand trap scraper with energy, a cable was automatically wound and unwound without protection and kept it constantly connected to power via a separate drive. The data and power cables have been laid in a very confined space, which has always led to a certain susceptibility to interference. In addition to the previously used classic copper cables, network and fibre optic cables are also used today, which could only be implemented with difficulty in a motor drum due to the insufficient spatial separation.
In addition, the topics of wear and tear as well as economic efficiency play an important role. All signals were transmitted and passed on from the drum's rotary movement via slip ring contacts. The contact points were subject to moisture and thus corrosion and had to be replaced regularly. Plant standstill is pre-programmed. In addition, frost plays a role in winter. The cable quickly becomes wet, freezes and therefore has to be heated in the cold season, which results in additional costs. The separate drive, the power consumption due to the separate heating, the maintenance effort as well as the insufficient volume in data transmission all speak in favour of relying on more powerful components with increasing economic efficiency.