Answering with innovations
Answering the important questions of our time has always been one of the biggest driving forces behind our success. Werner von Siemens made his mark on communications and electricity generation 160 years ago with his invention of the needle telegraph and the dynamo. Our more than 30,000 researchers in 30 countries are still asking themselves the questions of the times – and giving the answers.
Innovation at Siemens
Siemens is one of the most innovative companies worldwide: We register about 23 patents per day – a total of 5,000 in 2008. Our brightest brains are behind this: Researchers and developers who deal with a number of exciting tasks.
The world’s smallest ultrasonic device, a CO2 cleaning process for power stations – these and many others are the exciting latest topics from our research which we present in our Innovation News.
Siemens’ fields of research are as varied as our portfolio and a crucial part of our business strategy. Our R&D portal provides a good insight into our extensive research activities.
An environmentally friendly giant
Irsching, a picturesque little town in the idyllic Upper Bavarian landscape now has a special technological highlight to offer: Siemens installed the biggest gas turbine in the world at the nearby power station of E.ON Kraftwerke GmbH. The 13 meter long, five meter high and 444 ton heavy giant was built at the Berlin plant of the Siemens Fossil Power Generation Division. It was transported more than 900 miles by water along various rivers and canals and another 25 miles by road to Irsching. A bridge even had to be renewed to take the immense weight.
Superlative – also in the sense of the environment
The turbine by the name of SGT5-8000H features several superlatives: With a power of 340 megawatt – equivalent to the engines of 13 Jumbo Jets – it is also the most powerful gas turbine in the world. It can provide the entire population of a city the size of Hamburg (1.77 million) with electricity. And is environmentally friendly also. The gas turbine will set a world record in efficiency in full load operation with a down stream gas turbine. More than 60 percent, two percent more than the previous record holder, the Mainz-Wiesbaden power station. A higher efficiency means better environmental compatibility because much less fuel is required and less carbon dioxide (CO2) is emitted. This saves 40,000 tons of CO2 every year. In comparison with average modern coal-fueled steam power stations with an efficiency of 42 percent the power station in Irsching will save a total 2.3 million tons of CO2 per year whilst supplying the same amount of electricity
The tricks of the engineers
The Siemens engineers had to face two challenges to achieve this: They had to increase the quantity of air and combustion gases which flow through the turbine per second, the power then increases more strongly than the losses in the turbine, and they increased the temperature of the combustion gases which raises the efficiency. “It is technically very tricky to have hot gas with a temperature of 1,200 to 1,500 °C flow past the metal blades of a turbine because the maximum permissible temperature on the blade surfaces is only 950° Celsius. The surface then shimmers red hot. If it gets any hotter, it loses stability and the material oxidises,” Willibald Fischer, the developer responsible, explains.
The Siemens engineers used all their tricks to prevent this: They reduced the transition of heat from the combustion gas to the metal by using a thermal protection coating of two layers – a 300 µm fine adhesive coating on the metal and a thin ceramic coating on top which provides heat insulation. The blades are also actively cooled. They are hollow and air provided by the compressor is circulated through them.
“Grown” turbine blades
Another challenge for the engineers were the immense centrifugal forces. A maximum of 10,000 times the earth’s gravity acts on the ends of every turbine blade. The blades are made of a nickel alloy. They used to be cast and allowed to rigidify in the past but now the crystallites are allowed to grow specifically in the same direction in which the centrifugal forces act. The Giant of Irsching has blades in which the alloy has largely grown as a single crystal by special processes in the cooling. They are therefore particularly break-resistant because there are no longer any grain limits between the small crystals in the alloy which could serve as breaking points,
The engineers also optimized the shape of the blades with the aid of 3D simulation programs. The edge zones were designed so that the gap between the blades and the turbine wall stays as small as possible. Hardly any hot gas flows past the blades unused as a result. And the gap is reduced even more: Because the turbine is reduced conically, the shaft can be shifted a few millimeters in operation until the blades almost touch the housing.
Each of these measures on their own only brings a slight improvement in the efficiency or increase in performance but altogether they enable world record values.
