Autor: Roland Gruber , 20.04.2013

The Sohlstufe Lehen power plant in the heart of the city of Salzburg, Austria, will be put into operation in mid-2013. Works on the plant are currently being finalized.

Renowned Vöcklabruck-based Braun Maschinenfabrik delivered a moveable trash rack cleaner with an exceptionally strong performance. A true colossus of steel, the state-of-the-art trash rack cleaner with an articulated arm has a total length of 29 meters and a transport weight of 67 tons, which makes it a record-breaking job for Braun.

One of the most exciting and at the same time most ambitious power plant projects in Austria is set to be completed in the city of Salzburg, the home of Mozart: the Sohlstufe Lehen power plant. The motivation for the realization of this project encompasses not only the expansion of the production capacities of Salzburg AG, the energy supplier of the federal state of Salzburg, but also the  improvement of the flood control and the reduction of the increasing bed degradation of the Salzach River. Furthermore a near-by recreation area for local residents is being built. Thanks to its round and fluent shape the design of the new power plant will be in harmony with the cityscape of Salzburg. To guarantee that this requirement would be met the planning of the project was put out for tender beforehand. Yet another quality of the plant is its high environmental compatibility. The design fully guarantees the required ecological fish passing in the Salzach River at the existing vertical hard basin drop structure. Of course the new power plant will also meet all hydroelectric requirements. With a total installed output of 13.7 MW the plant will provide the local electrical grid with about 81 m kWh annually. This is sufficient electricity for approximately 23,000 households. Furthermore the green electricity produced by the plant will save 65,000 tons of CO2 on average per year. The construction works are in their final stages, the power plant will be put into operation in mid-2013.

The trash rack cleaner is a very important component in the construction of a run-ofthe-river power plant of this size and structure. It provides an unhindered flow at the fine rack and directly influences the total degree of efficiency and the plant's availability. Only a solid, efficiently operating and high-quality rack cleaner can prevent floating debris from affecting the power plant operation in the long run. With the trash rack cleaner of the Sohlstufe Lehen power plant experienced hydropower plant operator Salzburg AG relies on the expertise of Braun Maschinenfabrik, one of the most renowned companies in this field. With the contract for the trash rack cleaning machine with an articulated arm for the power plant in Salzburg, Upper Austrian-based Braun had to deal with entirely new dimensions. Measures and weight of the various parts are breaking most existing in-house records.

The movable trash rack cleaner is designed with an articulated arm and features a traction drive as well as a rotary drive. The balance weight, the cabin, the switchboard and the hydraulic power unit are installed on the rotating upper operator console. The main arm with a length of 14 meters and a weight of 7 tons is fixed on the upper operator console as well. During the cleaning process the cleaner rake, which is attached together with the grabber to the lower end of the 15 meters long articulated arm, enters the fine rack. At this stage the grabber is open. It is not until the grabber reaches the water surface that it closes around the debris. The cleaner rake is rotatable around the vertical axis and slews through the rotary drive. The collected debris falls into the rake through this “spooning-like motion.” Subsequently the grabber closes and the trash rack cleaner is moved to the container. For emptying the grabber bottom is slewed all the way down so the debris falls out of the rake. During this movement the grabber is securely holding on to all differently sized debris. Furthermore the movable trash rack cleaning machine has a built-in stop log lifting unit.

Braun Maschinenfabrik had to face huge challenges not only with the manufacture of the extraordinarily large trash rack cleaner, but also with its transportation, which was carried out in a heavy load transport at night. The lowbed trailer including the entire cargo had a weight of 80 tons. In March this year the experts of Braun delivered, installed and put into operation the colossus of steel. The installation of the trash rack cleaner was one of the last steps in the completion of the new plant. Judging by the high product quality for which Braun is known this important functional element will provide an unhindered flow at the inlet trash rack for many years to come.


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