Purification of black alkali liquor by microchannel filtration to promote energy savings and consumption reduction in lye cleaning systems

Abstract

Traditionally, multistage plate-frame filtration or centrifugal treatment methods are used to remove fiber from black alkali liquor with high viscosity and high fiber impurity content. However, these methods are limited by the long processes and high consumption of energy and materials. Therefore, in this paper, a new microchannel (deep) filtration process and device were proposed and used to replace the original “three-step” separation process (i.e., metal plate-frame filtration, first-stage polypropylene filtration and second-stage polypropylene filtration) and device. Separation media with different particle sizes were used to carry out online separation experiments. Results showed that an effective separation could be realized by using the combined multiparticle media with a length-diameter ratio of <30. Specifically, the average separation efficiency was higher than 90%. The workload was reduced by 66%. The floor area was decreased by 52%. The energy consumption was reduced by 64%. The material consumption was nearly zero. It is hoped that this study can not only benefit energy savings and cleaner production in the viscose fiber industry but also serve as a useful guide for other chemical industries.