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Reliable in wet, cold and heat

Energy chain system in the sand trap basin of the Bamberg sewage treatment plant

Increasing process reliability, minimising maintenance costs, transferring data in a future-proof 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 reliability. It replaces an ageing motorised cable drum. The cost-effective and low-maintenance complete system consists of a robust energy chain, various cables for power and data transmission and a stainless steel housing. Everyone involved is certain that the maintenance-free system will function without a hitch for many years to come.

Profile

  • What was needed: basic flizz system, consisting of energy chain, chainflex electrical cables, chainflex special cables with TPE outer jacket, condition monitoring system
  • Requirements: Long service life under continuous load (365 days/year in operation), resistant to weathering effects/corrosion-free, fast project realisation within a few months
  • Industry: Wastewater treatment plants
  • Success for the customer: Exceptionally low-maintenance energy chain, weatherproof solution that can withstand the elements, on-site installation and on-time completion within a very short period of time
basic flizz secondary clarifier

Problem

The mechanical biological sewage treatment plant in Bamberg with nutrient elimination is designed for around 220,000 inhabitants. Here, between 95 and 99 per cent of the substances contained in the wastewater are removed before being discharged into the Regnitz. The tasks are carried out by a total of 29 employees from the process engineering departments, an electrical and metalworking workshop and the wastewater laboratory.

In the area of the sand trap scraper, an outdated solution with an automatically winding and unwinding motor cable drum for power and data supply needs to be replaced. This original design 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 around the clock, 365 days a year. At the same time, there are strong weathering effects that have already taken their toll on the old system.

As the motor cable drum finally stopped working during the project planning phase, the new energy supply solution also had to be implemented within just a few months.

Solution

Today, a standardised basic flizz system is used to guide energy, data and air, which has proven itself in many wastewater treatment plants throughout Europe for years. The low-maintenance system covers travels of up to 100 metres and more. With its modular design, it combines the energy chain, chainflex cables and guide trough in a compact, weatherproof complete solution encased in stainless steel, which withstands the effects of weather such as sun, wind, snow and ice and functions reliably under continuous load.

In addition to chainflex electrical cables for the pumps and motor, the energy chain also includes chainflex special cables with a TPE outer jacket for outdoor use for data transmission. They are mainly assembled on site by the specialists or inserted into the chain.

A floating moving end, attached to the moving arm, compensates for lateral movements or the lateral offset of the scraper and ensures that the chain runs smoothly in the guide trough.

A condition monitoring system for additional push/pull force monitoring also provides the necessary system protection in the plant today. If the set value is exceeded or not reached, the system switches off automatically. This prevents cost-intensive malfunctions in advance.

"We are so satisfied that we are thinking of implementing this chain on the primary clarifier scraper as well."

Rainer Mild

Wastewater manager at the waste disposal and construction company of the city of Bamberg

Energy chain
Cables in the system

Technical disadvantages of the previous solution

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 were laid in a very confined space, which has always led to a certain susceptibility to faults. In addition to the traditional copper cables, network and fibre optic cables are also used today, which are difficult to implement in a motor drum due to the insufficient spatial separation.

Wear and cost-effectiveness also play an important role. All signals were transmitted and forwarded from the rotary movement of the drum via slip ring contacts. The contact points were subject to moisture and therefore corrosion and had to be replaced regularly. System downtime is pre-programmed. Frost also plays a role in winter. The cable gets wet quickly, freezes and therefore has to be heated during the cold season, which results in additional costs. The separate drive, the power consumption due to the separate heating, the maintenance effort and the insufficient yield in data transmission are all arguments in favour of using more powerful components with increasing efficiency.

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