Reed Three-Stage Counter-Current Batch Cooking with Ethanol-Water

Abstract

This article studied the pulp contrast of reed three-stage counter-current cooking and single-stage cooking, meanwhile analyzed the regulation of the yield , the hardness of pulps and the properties of the waste liquor from each cooking stage of reed three-stage counter-current batch cooking with ethanol-water process. The SEM and IR-FT were employed to gain more understanding on the change of lignin on fiber surface and the structural change of lignin separated from waste liquor of each stage. The results show that single-stage cooking need to keep 190°C for 4.0 hours to get the best results, while the three-stage counter-current cooking need 1.5 hours more, but the highest temperature fallen by 20°C and the screened pulp yield increased by 3.9%, also the Kappa number decreased by 11. In the process of reed three-stage counter-current batch cooking with ethanol-water, the degradation and removal of lignin and glycan occurs mainly in the first stage. After the first stage cooking, most fibroblasts did not reach the fiber separation point and the screened pulp yield is only 38.7%. After the second and third stage cooking, the fiber separation became better ,the screened pulp yield increased to 49.72% and the Kappa number decreased to 25.6 . As the analysis of the results from the each-stages lignin by IR-FT, the structure of lignin had no significant difference .