Developing decentralised solutions – Generate power from ind
With advancing changes in the energy sector, interest in decentralised, variable power generators is growing. The use of waste heat from industrial processes can significantly contribute to increased energy efficiency and the generation of low carbon power. The Organic Rankine Cycle (ORC) takes a technological approach to the conversion of waste heat into power. For over 7 years, a Northern Bavarian consortium, consisting of the University of Bayreuth, OTH Amberg-Weiden Technical College and the company DEPRAG, have been successfully developing ORC systems, specifically, micro expansion turbines in low power ranges of under 50 kW (electric).
The recovery of unused energy, such as the heat in exhaust gases from combustion engines or gas turbines or even the waste heat from industrial processes, is a promising strategy to address the challenge to increase energy efficiency. The existing technical solutions, such as downstream steam power processes or turbines as expanders of natural gas, are limited to energy flows with a temperature of over 500 °C and an electrical system output of over 100 kW. In order to achieve stronger market penetration and a tangible positive impact on today’s energy system, it is vital to tap into the substantial potentials at lower temperature levels.
The concept: An efficient, small-scale ORC turbine
The ORC is particularly suited to the conversion of energy from heat sources with temperatures of 100 °C to 500 °C. In principle, this is the traditional steam power process named after the Scottish physicist and engineer William John Macquorn Rankine (1820 – 1872). In contrast to conventional generators, in ORC systems however, the working medium is organic fluid instead of water. These materials have the advantage of turning to steam at comparatively low temperatures. This technology has not yet been sufficiently established in an electrical power range lower than 100 kW. This is due, amongst other things, to the lack of cost-effective micro expanders with generators. The group of partners have taken exactly this approach with their intensive research and development work. Firstly, a new type of highly-integrated turbine generator unit has been developed which is comprised of an axial impulse turbine with hermetically sealed synchronous generator (turbine image). Furthermore, an innovative heat exchanger design (plate and shell heat exchanger) has been tested to directly connect the ORC working medium with the exhaust gases. These measures avoid cost intensive intermediate circuits.
More information: DEPRAG SCHULZ GMBH u. CO.
