The objective of this project was to study systematically the NSSC-AQ pulping process in order to improve the penetration of anthraquinone and sodium sulfite in wood and to simulate the mass transfer and delignification processes. / In a heterogeneous reaction system, such as wood pulping, two main factors control the overall reaction rate: liquor penetration and chemical diffusion. As a first step, some wood characteristics affecting liquor impregnation were evaluated: 1) fiber hydraulic radius, 2) air, steam and water content, 3) wood elasticity and compressibility. Secondly, impregnation and pulping experiments were performed while varying the pre-steaming, compression and soaking time. Finally, experimental profiles were compared to computer simulated results. The two most commonly used species by the pulp industry were chosen for this study: 1) black spruce sapwood and heartwood as well as 2) trembloid poplar sapwood. / Impregnation of sulfite-AHQ liquor in wood blocks was simulated by a three-dimensional "Control Volume Finite Difference Method (CVFDM)". To de-couple the pressure and velocity fields, typical to convection-diffusion problems, a mass balance around individual control volume was performed using Poiseuille's capillary flow equation. The pulping kinetic differential equations were included into the CVFDM model to simulate a three-dimensional delignification pattern in the wood. / In general, the progression of the anthraquinone impregnation was slow and non-uniform in comparison to sulfite which penetrated rapidly and uniformly during pulping. Furthermore, delignification uniformity was related to the initial chemical profiles observed after impregnation. This confirms the importance of chemical pre-treatment for high yield pulping in order to minimize uneven delignification for chips thicker than 3mm. Results showed that, in most cases, computer simulated profiles were similar to experimental anthraquinone and sulfite impregnation patterns.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28495 |
| Date | January 1994 |
| Creators | Morin, Francois |
| Contributors | Kubes, Georges J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001425211, proquestno: NN00115, Theses scanned by UMI/ProQuest. |
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