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| Authors: | Inalbon, María Cristina |
| Title: | Mechanism and Rate of Alkaline Impregnation of Wood |
| Keywords: | diffusion / impregnation / softwood / effective capillarity / deacetilation / Kraft / |
| Abstract: | The alkaline wood chip impregnation, aspect of great importance in the Kraft pulping, is studied.
The phenomenon is analyzed as isothermal and unidirectional, where the alkali reacts and modifies the wood chemically and physically. The relative importance of the diffusion, chemical reactions and swelling are evaluated.
The deacetilation kinetic (main reaction) is determined for eucalyptus in conditions near and comparable to the industrial ones. It shows be dependent on the temperature, the concentrations of acetyl group and alkali and the solution ionic strength.
The effective capillarity, intrinsic property of the wood, is used for the diffusion analysis. Its dependency with the temperature, ionic strength, pH, and degree of chemical action is determined, being the influence of the chemical attack the most important one.
The ion concentration profiles and advance degree of reactions in the solid impregnated wood are experimentally obtained under different conditions, similar to those of the industrial process.
A mass balance for the main species involved is considered. The study takes into account the relevant chemical reactions involved and the temporal changes of the wood properties at each position of the chip due to the alkali action. The numerical resolution is made using the program gPROMS (general PROcess Modeling System).
The general patterns found for the simulation of the alkali impregnation phenomenon are in acceptably good agreement with experimental results.
The effect of the main process variables (external alkali concentration, temperature, time, and chip thickness) can be analyzed through the proposed model. |
| URI: | http://bibliotecavirtual.unl.edu.ar:8180/tesis/handle/1/102 |
| Date: | 18-Mar-2008 | | Advisor: | Zanuttini, Miguel Angel Mario | | Co-Advisor: | Mussati, Miguel Ceferino | | Thesis Approval Committee: | Maria Cristina Area, Diana Estenoz, Mirta Inés Aranguren | | Sponsorship: | Consejo Nacional de Investigaciones Cientificas y Tecnicas - Beca Doctoral, Agencia Nacional de Promocion Cientifica y Tecnologica - Beca Doctoral- Proyecto: PICTO 2007 Nº36150, Universidad Nacional del Litoral - Proyecto: PICTO 2007 Nº36150, Universidad Nacional del Litoral - Proyecto CAI+D 2005 PI 004-18 |
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