As part of the EU-project DryFiciency, SINTEF is developing and testing a novel compressor type together with ROTREX: a so-called turbo compressor. The challenge was to design a gearbox which results in a rotational speed of up to 80.000 rpm for an impeller size of 15 cm and at the same time seal the compressor room from the drive unit. This week the factory assembly tests were finalized successfully and the design is approved for a heat pump application and other steam compression processes.

"This is an important step forward in achieving the main goals of the project: Improve process energy efficiency by up to 80%, reduce production cost by up to 20%/kg and reduce CO? emissions up to 75%." (Michael Bantle, Senior Research Scientist, SINTEF Energy Research, Department of Thermal Energy)

The compressor will be used to recover the drying energy of steam drier and upgrade it into usable process heat. In steam drying processes, products are dried in a steam atmosphere. Today, steam is circulated and reheated by a natural gas burner, emitting the greenhouse gas CO2. The water removed from the product is present in the form of excess steam.

Usually, the energy in the excess steam cannot recovered, because there is no heat demand at this low temperature, and it is therefore wasted. Open loop heat pump systems, also known as Mechanical Vapour Recompression (MVR) systems, allow the reuse of the excess steam to heat the process, which is developed by the DryFiciency consortium.

Find the complete article by Michael Bantle here.