PULP DRYING WITH SUPERHEATED STEAM UNDER PRESSURE .3. OPERATING MEASUREMENTS ON SEVERAL EVAPORATION DRIERS AND BASIC RESEARCH

Evaporation drying in a fluidized bed is a novel system of pulp drying in sugar industry, contrary to the hot gas drying in drum driers. Thi s new system has been installed in several sugar factories in eastern parts of Germany. The Braunschweig Sugar Institute has conducted perfo rmance tests and basic research on this new drier type. The performanc e tests covered both the operations with full load and with partial lo ad. The operation with partial load could only insufficiently reduce t he steam superheating due to the low level of pulp. An extended retent ion time of the pulp might improve the utilization of heating energy o f the turbine bled steam. However, the quality of the product ''pulp'' , which is sensitive to heat, has to be considered. Topics of the basi c research are drying rates, drying periods and sorption isobars for t he evaporation drying of beet pulp. Pulp samples taken from several ce lls of the drier were analized concerning their dry substance content. These values were compared with the course of the dry substance conte nt supplied by an enthalpy balance for the circulating steam inside th e separate cells. Further studies will concentrate on the determinatio n of the equilibrium moisture of pulp depending on parameters of the s uperheated drying steam.