Gas flow acceleration classification of polyvinyl alcohol (PVA) to promote energy saving in pulverizing system

Polyvinyl alcohol (PVA) is an important biocompatible synthetic polymer with pervasive applications. Classifying out particles with a size of less than 120 um from PVA is a key process related to energy saving and cleaner production. In this study, gas flow acceleration classification method was developed to enhance PVA classification. The movements of differently sized PVA particles in the classifier were directly measured by a self-designed high-speed camera system. The efficiencies of one-stage and two-stage gas flow acceleration classification were systematically analyzed by means of laser scattering, standard sieve and scanning electron microscope (SEM). The mean diameter of the PVA particles at the inlet, top outlet of the first stage, bottom outlet of the first stage, top outlet of the second stage and bottom outlet of the second stage were 291 mu m, 173 mu m, 434 mu m, 141 mu m and 292 mu m, respectively. This study also obtained the proportion of fibrous particles in the PVA through a 13-day continuous experiment. Gas flow acceleration classifier instead of rocking sieve in industry can reduce energy consumption of pulverizing system by 50%. This study not only benefits the energy saving and cleaner production in the PVA industry, but also serve as a useful guide for other powder and chemical industries. (C) 2019 Elsevier Ltd. All rights reserved.