Air-supported belt conveyor

In contrast to the conventional design of a belt conveyor, in which the upper strand of the belt runs over idlers that both limit the sag of the belt and cause it to trough, in this type of conveyor the belt runs through a pipe. The design has several advantages:

• There is virtually no slack in the belt and it does not wander up and down between the support stations. This reduces the required drive power.
• The material is protected from the weather and the environment cannot be affected by the material (dust, dirt).
• Perfect belt troughing leads to better support of the bulk material and stability of the particles. This allows inclinations of more than 30° in the case of plug conveying, although the belt is not fitted with carriers.
• A special belt is used which has a bottom cover consisting of open fabric. This reduces the frictional resistance in the pipe.
• In addition, air can be blown into the supporting pipe from below and the belt runs on a cushion of air, which reduces the sliding friction in the pipe and results in a very low drive power requirement.

Supporting structures of the air-supported belt conveyors:

The supporting pipe rests on support flanges on the bottom chord level. Here "bottom chord” refers to the platform-like support layer of the steel structure. The combined cross-section of the pipe and steel support layer stabilises the structure both vertically (dead weight, bulk material and snow) and hori-zontally (wind). The support spacing distance is increased compared to the variant in which the weight is borne by the pipe alone.

In order to achieve particularly large support spacing distances of up to 76 m, the air-supported belt conveyor can be suspended on cables between pylons.

Air-supported belt conveyors are thus used as

• steep conveyors with angles of inclination up to 30° and greater
• Belt conveyors with very large support spacing distances of up to 76 m and very large axial distances of more than several hundred metres

The air-supported belt conveyor requires very little maintenance, as virtually only the return rollers in the lower run of the belt have to be inspected and replaced. Idler rollers are lubricated for life and do not need to be re-lubricated during operation.

Nevertheless, in order to perform an inspection of the conveying line the conveyor can be equipped with an auxiliary device:

The inspection trolley is an innovation developed by the Klamke engineering office and is not yet state of the art. The trolley is equipped with electrical equipment consisting of a

• battery
• DC/AC converter
• frequency converter

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This allows the trolley to travel up and down the full length of the conveyor one and a half to two times before the battery needs to be recharged. The bottom chord level of the steel support structure (see above) serves as the trolley support frame.