Fig. 4 Michael Schmidt has invested a quarter of the development work for the new ORC technology in the control and regulation technology.
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Field test started

“We have developed a highly efficient ORC process for waste heat flows between 200 and 500 °C, which in Germany is suitable for up to 500 industrial enterprises and around 1,000 larger CHP plants with capacities exceeding 1.2 MW,” says Schmidt in reference to the field test that is now beginning with four different plant types. “In contrast to turbines, our engine is not dependent on the rotational speed, which means that the fluctuating heat flows are also highly suitable for partial-load uses. Instead of electricity, we can also sell mechanical shaft power that enables, for example, compressed air to be produced from exhaust heat.”

The field test will show how the overall system copes after many thousands of operating hours. In addition to a biogas plant near Bremen, the waste heat from melting tanks in the glass industry and from casting kilns in the metal and chemical industries shall be used in test plants. “All this is being conducted with proven industry partners to ensure that we achieve market maturity in 2013 as planned,” emphasises Schmidt. The six ORC modules with their steam expansion engines shall then be transferred to a metal foundry in Bad Kitzingen, where a project funded by the German Federal Environment Agency has just begun. By launching the first large-scale use of the innovative plant combination for utilising exhaust heat, the company wants to reduce its CO2 emissions by more than 8,000 tonnes a year. In addition to electricity, the use of steam expansion engines instead of conventional turbines and the use of ethanol instead of silicon oil as the ORC working fluid will also enable compressed air to be produced.

For the field test, the developers are installing the ORC module in a standardised container. Because the heat exchanger is placed outside the container, the system can quickly adapt to the respective heat source. Even with the very first “Kirchwalsede” field test plant, which is a biogas plant near Bremen, only those components are included in the container that will be standard in every new ORC system. These comprise the machine bed with the steam expansion engine along with the generator, oil cooling system, pump station, technical ventilation and switch cabinets, which contain the proprietary developed control and regulation unit. Within the container, the engine, pump and switch cabinets are located in separate rooms. This enables all parts of the ORC module to be accessed separately. The engine is positioned so that it can be removed from the front end without any great effort and without having to dismantle the generator by using either a mobile crane located in the container or a standard forklift truck. This makes it easier to maintain and enables it to be completely replaced much more quickly.

In order to save on space and also foundations for further components such as the heat exchanger and emergency cooling systems, the Saarland researchers have developed a separate roof structure that will be placed on the container with a suitable frame. The container has been structurally redesigned, strengthened in accordance with the load distributions and tested. This reduces the overall floor space for the plant to the size of a 30-foot container (9 m length).


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Steam expansion engine
DeVeTec GmbH

Working fluids
Evonik Industries AG

Heat exchangers