Agrana - Food industry

AGRANA operates many kinds of such dryers in its 54 sugar and starch factories for product and by-product drying. The drying air (or superheated steam) is usually heated by natural gas. While heat recovery from the exhaust gas is common, significant amounts of energy cannot be recovered due to lack of appropriate heat sinks. By boosting the temperature level with an industrial heat pump, a considerable amount of energy can be recirculated into the process. Some applications would even allow for closed-loop-dryers at the proposed temperature levels. In these cases, thermal energy would only be required during the start-up phase; during stationary conditions heat pumps could provide all of the required thermal energy. Agrana’s name is synonymous with refinement of natural, renewable raw materials. During this project major steps will made towards making Agrana also ready for renewable energy and respective customer demands.

Process description:

The first demonstrator will be installed in the production and drying of starch from potato, wheat and corn. The useful supply temperature of the novel heat pump system will be around 130 to 160 °C; the heating capacity will be around 600 kW. 


Starch is dried by using hot air. Heating of the air is realised in three consecutive steps, namely preheating by a heat recovery cycle (HRC), heated by waste heat from another dryer, heating by steam condensate and heating by steam After reaching the target temperature, the air is sent to the dryer. To gain more energy from the HRC, a demonstrator heat pump unit (600 kW) will be installed. This unit will use heat from the return of the HRC as a heat source, and will supply this heat at temperatures up to 160 °C to the heat exchanger. The demonstrator unit implemented in Dryifciency will cover approximately 25 % of the full heat recovery potential available on site.

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