Abstract: In this study, bleached shellac was dried with fluidized bed for the purpose of raid drying at lower temperatures. The two main factors, including inlet air temperature and air flow rate, which influence the product color index and drying time, were investigated using one-factor-at-a-time method and response surface methodology (RSM) with central composite experimental design. A regression model was established for each response. The results showed that the predicted value agreed well with the measured one, with an error of only 1.12% and that the two models (R2 = 0.949 1 for color index, R2 = 0.937 7 for drying time) could be used for describing and predicting the fluidized bed drying of bleached shellac. The optimal operating conditions were determined as follows: drying at 36 ℃ at an air flow rate of 45 m3/h for 28 min, resulting in a color index of 0.90. The dried product reached the Chinese national standard for the highest quality grade of refined bleached shellac.

Key words: bleach shellac, fluidized bed drying, response surface methodology