Hydro Power Case

During 2010 a major Austrian hydropower project was started and visitors to the area would have been blissfully unaware of it. The site, known as Limberg II, is reached along a 7 km tunnel climbing inside the mountain. It’s a gigantic project inside the mountain and is designed to supplement and optimise the existing Kaprun storage power plants.Verbund–Austrian Hydro Power AG (AHP) operates the Kaprun group of plants and generates a third of all the electricity consumed in Austria.

At the end of 2011 when the new plant is expected to start up, the turbine output will increase from 353 MW to 833 MW. It will make optimal use of the difference in height between the existing Alpine storage lakes “Mooserboden” and “Wasserfallboden” (respectively 2,036 and 1,672 metres above sea level). These two lakes hold a total of 166million cubic metres of water, all of which can be converted to electricity at the touch of a button.

This area of Austria is a very popular tourist destination and the reason Limberg II was built completely underground was in order to fully protect the environment. 70,000 cubic metres of rock has been excavated just to build the power and transformer caverns; as a result the plant is completely invisible.A big dome inside the mountain, 43 metres high and 62 metres long, houses two reversible centrifugal turbines generating 240 MW each, manufactured by Voith Hydropower of St Pölten,Austria.A steel lined penstock over 5.4 km long, with a diameter of 4.8 metres, in the right flank of the valley connects the two reservoirs.

At times, when the demand for energy is low and therefore energy prices are also low, water from the Wasserfallboden lake may be pumped back into the higher Mooserboden, allowing it to be used several times to generate valuable peak demand electricity. Consequently, Limberg II will make an important contribution to the Austrian electricity supply.

The conduits and penstocks must be properly protected from the effects of fast flowing water and mild abrasion caused by any sediments present together with the aggressive action of any small particles on the internal steel surfaces. In order to achieve this, AHP specified the use of Irathane® 155, a specialist coating material to line the spiral cases around the two turbines, using an average coating thickness of 1.5 mm. AHP has over 20 years experience of using our coating. Consequently, they are extremely confident in its long term performance. 

Irathane® 155 is a two component elastomeric polyurethane coating with exceptional abrasion resistance, first developed for the mining industry in North America. A brushable version of Irathane® 155 was used to coat the most intricate parts of the spiral cases. Irathane® 155 can be applied on various types of hydro-mechanical equipment and on some turbines - both in the workshop or on site – and the cured coating is considerably tougher and longer lasting than the surfacematerial that it protects.

Due to severe operating conditions (around 70 bar pressure), Irathane® 155 has to bond well to the steel surfaces and the process must be undertaken with skill by the contractor. In the case of this project, the coating work was undertaken by Bauschutz Gmbh based inWelz, whose project manager Anton Paslar has 20 years experience of using Irathane® 155 in penstocks and turbines. Bauschutz is the leading industrial coating contractor in Austria, with particular expertise in the hydropower generating industry. Anton says he has worked all his life in ‘holes’ and has managed many projects using Irathane® 155.Whereas this coating can be applied on an entire penstock if required, for cost reasons, Bauschutz chose to use it solely where they believed it would be of premium value at Limberg II, that is to coat the most critical parts. Over the years, Austria has proved to be a major market for Irathane® 155 because the coating is designed to give excellent protection against cavitation and erosion, both of which are commonly encountered in this industry. Water from glaciers may not be the most aggressive, but after twenty years of using Irathane® 155 companies like VoithHydro continue to work closely with Irathane Futura to provide long term, problemfree coating solutions, as well as recommending Irathane Futura to their customers world-wide

Applied Products 

ITW Engineered Polymers