Which is the best way to supply energy to the mobile scraper of a clarifier?
The Aggerverband decided against the conventional solution with cable drum and opted for an igus® LBT flizz® energy supply system. The result: The system has been operating without any interruptions at the Waldbröl-Brenzingen sewage treatment plant since the year 2000.
The longitudinal scraper in a final clarifier travels by means of a gear wheel drive at a speed of 1m/min
24 hours a day, 256 days a year. The scraper requires energy and control signals just like pumps below the water surface. Originally, a cable drum was used for the energy supply. The people in charge were not very happy with this solution, because with every forward and backward movement, the cable completed a drill movement that contributed to increased wear.
With the LBT flizz® system, igus® offers a weather-resistant energy supply system that can be adapted for the respective application conditions through its modular design. Both the plastic components and the metal parts are protected against corrosion in the long term. The closed-top trough prevents the intrusion of snow and leaves and contributes to a smooth operation of the system. Very aggressive gases like the hydrosulfide mixture that emerge in the waste water treatment do not disrupt the operation of the flizz® system. The worst case scenario would be the freezing of the chain at the LBT plastic profile and the consequent failure of the plant at temperatures below 0° C. Due to the small contact surface of the chain to the trough and the special shape of the LBT-flizz® profiles, dangerous forces do not develop even during freezing morning dew.
Altogether 38 meters of guide trough was installed at the final clarifier. The cables are about 20 meters long; besides the electric cables for the three pumps and the mobile motor, 16 communication cables as well as a special bus cable are accommodated in the trough. The individual igus® chainflex® special cables of the CF9, CF10 and CF31 series have a TPE outer jacket and can be used in temperatures ranging from -25° to +100° with a minimum bending radii of 5xd. The proven and tested chain of the Series E2, Type 250.07.100.0 was used as the energy supply chain.
A lateral off-set of up to 150 mm should always be calculated for longitudinal scrapers of this type series. To compensate this cross traverse, igus® developed a cost-efficient floating moving end and installed on the tow arm of the scraper bridge.
The system has been working without any problems since its installation over 5 years ago. It is not surprising that the Aggerverband is satisfied with the solution and the igus® services scored high points.
Due to the rugged design, many other application potentials have already been realized, for instance in rain overfall basin or in harbor cranes. Moreover, the components are resistant to the common chemicals, fat and solvents. Therefore igus® supplies the LBT flizz® system also to the manufacturers and operators of galvanic equipment and other chemical engineering plants.