AVG Köln, operator of a modern waste incineration plant, has renewed the energy and signal supply system for its four bunker cranes. Roller energy chains from igus are used for this. The "heavy duty" chains, which run with much less friction than gliding chains, require only about 25% of the otherwise usual drive power and work reliably even under the most adverse environmental conditions. The customer benefits from a reliable energy supply solution installed by igus without interrupting ongoing operations.
The incineration plant in Cologne, which opened in 1998, turns waste into energy and is particularly efficient in the process. The reason is that, in contrast to other residual waste incineration plants, it first sorts and mixes the waste to be incinerated.
After a metal separation process, the different waste streams are intensively mixed and then placed into the residual waste bunker. From there, grab cranes fill the hoppers of the four boilers. The four bunker cranes are heavily loaded at AVG, which incinerates around 710,000 tons of residual waste. The moving parts especially are subjected to severe stress due to the large amounts of sticky debris that are inevitably produced in such plants.
This also applies to the energy supply for the cranes. Dipl.-Ing. Oliver M. Hamm, is the operating engineer responsible for the electrical and control systems: "In the course of preventive maintenance, we looked around for a new system for supplying energy and signals. The existing trailing cables were and still are intact. But we have to be prepared in case a cable becomes irreparably damaged. This would lead to interruption of the energy or signal supply. We would then still have some time in which to repair the defect. But we would have to put an alternative system into operation within a reasonable amount of time in order to ensure the availability of the cranes. “
When it came to the selection of a new energy supply system, attention soon focused on energy chains – or, more precisely, on a heavy-duty roller energy chain from igus.
The encapsulated design of the rollers and the high tensile strength of the chain ensure trouble-free operation, even under harsh conditions such as those present in the residual waste incineration plant. The "roller e-chain" is also characterised by a very high degree of torsional stiffeness. Moreover, the entire construction is designed in such a way that a high degree of resistance to wear is guaranteed, even under tough conditions. In this way, the rolling resistance remains low even in applications where dirt and debris is present. Another reason for opting for the roller energy chain on the operator side was the higher flexibility. If other controls are used in the future, additional cables can simply be inserted into the chain. That can't be done with trailing cables. This is why only around 75% of the space in the chains is used. Each of two chains running in opposite directions to each other is housed in a trough: power is fed in from the middle. A floating moving end provides horizontal and vertical compensation
The solution also includes an Easy Push/Pull Detection System 2.0 condition monitoring system for energy chains, which is installed on each individual moving end. The system monitors the displacement forces of the energy chains and, if a defined force is exceeded, causes the movement to stop immediately to prevent potential damages.
Installation of the four energy chain systems in the two bunkers proved to be a real challenge. Dieter Reitz: "As the plant operates continuously, there were only very short periods of time at the weekend when our fitters were able to work in close consultation with the shift management and after strict safety precautions had been taken. " The material, which was first placed on the bunker and was brought in through a hatch, could only be installed in short intervals and after strict safety precautions had been taken. This work therefore required four weekends for each crane since pre-assembly of the chains in the factory was not an option. Dieter Reitz: "We had to proceed step-by-step and first lay the chain and then the cables - the system in its entirety would have been too heavy and unwieldy to bring into the bunker. "
All in all, it was a considerable logistical feat that the igus fitters had to perform: "We layed 10.65 t of troughs and 640 meters of cable trays. In the energy chains, there are 26km of cable and 29,218 separators. We screwed in 2,800 bolts and connected 4,474 wires. “