The energy fed to the co-generation unit is converted to electricity and process heat at the same time. The first Dürr ORC system integrated in a co-generation unit has been used successfully by the municipal utilities Stadtwerke Groß-Gerau (Federal Land of Hesse) since 2012 and has proved its worth. Coupled to a biogas plant, the system boasts an availability of over 98%, after more than 15,000 operating hours.
There are other fields of application: The company Naturenergie Hersbruck, headquartered near Nuremberg, is the first to use an ORC unit in connection with a biomass heating plant operated with a heated gas turbine. Here, electricity and heat are generated by means of timber residues from forestry. Now, the output of the ORC unit has grown by 120 kW, increasing the total efficiency of the plant by 8%.
Starting at the end of this year, the ORC technology by Dürr Cyplan will be used in Switzerland in combination with a wood firing system in a 350 kW ORC plant. Connected to the wood firing system via a thermal oil circuit, the ORC plant generates electricity and heat from timber residues in an environmentally friendly manner.
It is one of the great benefits of the ORC technology that waste heat with a temperature as low as 90 °C upwards can be used for electricity generation. Another is the large number of possible applications for interfaces with hot water, steam, thermal oil or hot gas. This is evident, for example, in a geothermal power plant in Indonesia, which will be upgraded next year with a 500kWel ORC unit. The geothermal power plant uses steam to drive turbines and generate electricity. High-pressure hot water from a reservoir in the earth’s interior rises to the top through a borehole and evaporates in the power plant upon decompression. The steam is fed into the turbine, which produces electricity by means of a generator. Any water that has not evaporated is re-injected into the earth’s interior while still hot. In future, the ORC system will be integrated into the cycle before the water is re-injected into the earth, increasing the efficiency of the system as a whole. With the thermal energy in the hot water, the ORC system can increase the amount of electricity generated by up to 10%.
In October 2012, Dürr Cyplan palced first in the “Energy Efficiency” category of the Baden-Württemberg Environmental Technology Awards for its ORC plants suitable use in co-generation units. Today, most customers opt for this variant of the technology. Decentralized energy systems often use the waste heat of the motors of co-generation units. With the Dürr Cyplan ORC technology, it is possible to increase the output by more than 10% while exceeding 19% of electrical efficiency.
"The new applications show the great variety of potential target fields for our ORC technology," says Jochen Fink, Managing Director of Dürr Cyplan. "Our customers wish to increase the efficiency of their energy systems while enjoying the benefits of heat utilization."
Mr Fink explains: "It is our goal that these plants make use of the huge potential of industrial waste heat to generate electricity." In the future, Dürr Cyplan will therefore offer its customers a test stand for simulation of solutions for electricity generation from waste heat so that they can see for themselves how powerful the technology is.