Pulp drying with superheated steam under pressure – Part 2: The procedures adopted by Könnern sugar factory

The concept of drying sugar beet pulp by means of superheated steam is described by the example from the new sugar factory of Diamant-Zucker in Könnern. The integration of two steam driers of the NIRO type 10 was made by incorporating these as steam pressure reducers between the turbine and the 1st effect of the evaporator station. The power requirement of the factory was thus almost totally fulfilled through own power generation using a pass-out back-pressure turbine, supplying steam between 11 and 18 bar for the driers. With this layout, drying of 60% of the beet pulp was assured. Between the two campaigns, various improvements were made which resulted in a significant increase of the plant availability. The water evaporation guaranteed by the manufacturer was confirmed through a series of measurements. The condensate arising from the drying vapour can be purified without problems in the factory’s own water treatment plant. The condensate contains mainly organic acids, which are easily degraded. The problems with the rotary valves are described. As well as the improved valves from drier manufacturer, alternative conical rotary valves made of highly wear-resistant materials were successfully utilized in 1994.