Whether for boiling, drying, steaming or in power plant processes - numerous companies in the manufacturing industry, in chemical parks or in the energy supply sector generate steam. In many cases, steam is still controlled by mechanical valves, which means that a great deal of energy potential is not utilised. The Herten-based technology company Turbonik has developed a micro steam turbine (MST) specifically for the control of process steam, with which companies can reduce their energy costs - and even supply entire settlements with electricity. For the first time, MSTs enable companies to generate their own electricity profitably and save CO2 in the power range up to 300 kilowatts. You only need a little steam to generate a lot of electricity.
Turbonik has been producing and selling this turbine since 2017, but ‘the story goes back even further,’ explains Managing Director Martin Daft. Many years of research work in a Fraunhofer project on the conversion of waste heat into electricity laid the foundation for the development of the new micro steam turbine for water vapour. Back in the early 2010s, the Fraunhofer Institute UMSICHT in Oberhausen had already been researching the optimisation of ORC systems and turbines. ORC stands for ‘Organic Rankine Cycle’ - a process for generating electrical energy in which waste heat heats an organic medium via an evaporator. Even at relatively low temperatures, a high vapour pressure is built up here. The difference in pressure drives a turbine and thus the generator. ‘These turbines,’ says Daft, ’do not use water vapour, but a kind of petrol vapour.’
The next question is: What else can be done with all this accumulated knowledge about turbines? The application concept itself, including the use of steam, is not new: large industrial turbines for a wide range of applications have been around for over 100 years. However, with small amounts of steam, conventional turbines have not been able to economically utilise the energy in the steam to generate electricity. What was missing were small steam turbines with high efficiency.
Turbonik's micro steam turbines are now aimed at precisely those companies where steam volumes and space requirements are not sufficient for conventional turbines. And score points here above all with performance. ‘Our turbines run at up to 50,000 revolutions per minute, whereas large steam turbines tend to run at 12,000 to 15,000 revolutions,’ explains Daft. ‘This makes us extremely efficient in this low power range. This means that we get 40 per cent more electricity out of the same fuel energy than conventional machines.’ If a Turbonik micro steam turbine runs continuously at a maximum output of 300 kilowatts, it can generate up to 2.5 gigawatt hours of electricity.
An optimised blade design and the direct coupling of turbine and generator ensure that the MST is significantly more compact than a conventional steam turbine. ‘The machines fit on a Euro-pallet,’ explains Daft. ‘The impeller at Turbonik weighs around 1.5 kg. The machines that were previously available in this power range have impellers weighing around 40 kg, but are not as efficient.’ Micro dimensions with macro efficiency, to put it simply. In the future, the Herten-based company will go one step further and launch a model with an output of up to 600 kW.
A recent example is the waste incineration plant GMVA Niederrhein in Oberhausen. When the waste is incinerated, things get hot: temperatures of up to 1200 degrees are generated in the plant's four boilers, which are used to produce steam at high pressure. Most of this steam is utilised by large turbines to generate electricity and provide district heating. However, until 2023, there were still sub-processes in the overall system of this plant in which the steam pressure between a medium-pressure section and a low-pressure section was not controlled by turbines but by conventional valves. The enormous potential from this pressure difference remained unutilised.
‘At GMVA, we are constantly working to improve ourselves and increase energy efficiency by utilising new technologies and processes,’ says Frank Nachtsheim, Managing Director of GMVA. ‘The use of a micro steam turbine, with which we can generate additional electricity from existing processes was therefore only logical and sensible for us. The MST has been producing electricity here since 2023, helping to ensure that the fuel already used to generate steam, namely waste, is used even more efficiently in the interests of the circular economy. ‘In Germany, we are working on the serious assumption that demand for electricity will continue to rise,’ says Daft. ‘This means that the continuous provision of affordable energy is a major issue for local authorities and companies.’
The target group for the MSTs are steam-using companies from various industries that want to design and optimise their power supply: In addition to public supply, for example in power plants and waste incineration plants such as GMVA, the turbine can also be used by operators of process steam plants, for example in paper mills, steelworks, the chemical industry, wood processors, automotive suppliers and recycling companies. A large amount of energy in the form of steam is also required in the food, animal feed and pharmaceutical industries, including for drying processes. Daft: ‘As a rule, it is particularly important that the steam used is clean.’ The advantage with Turbonik: The MSTs are completely oil-free. For the first time in steam turbines, water is used as a lubricant. ‘So there is no oil to dispose of. And we have extensive documentation and reporting obligations in Germany, especially with regard to environmental aspects. If no oil is used, this saves time and money.’
The possible applications of MSTs are therefore diverse. Nevertheless, waste incineration at GMVA Niederrhein is a special project for the Herten-based company. Especially with the phasing out of coal-fired power plants, there is enormous potential here. Daft: ‘Many local authorities have a stake in waste incineration plants. They need a secure, clean and affordable electricity supply for their citizens. And we are an important piece of the puzzle here.’ In the Ruhr metropolis, but also beyond.
Regional co-operations
In this project, contributions to greater energy efficiency from three Greentech.Ruhr network partners become visible: Remondis and the cities of Duisburg and Oberhausen are involved in the GMVA waste incineration plant, the micro steam turbine was developed at the Fraunhofer Institute UMSICHT and Turbonik GmbH has introduced it to the market. The sustainable side is combined with the economic side: The turbines are designed for a 20-year service life, while according to Turbonik, the plants usually amortise between 1.5 and four years.
www.turbonik.de
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