Impregnation of eucalyptus and pine Impregnation of eucalyptus and - PowerPoint PPT Presentation

Impregnation of eucalyptus and pine Impregnation of eucalyptus and pine wood in alkaline pulping processes. wood in alkaline pulping processes. Effects of steaming and pressurized Effects of steaming and pressurized impregnation impregnation Inalbon M.C., M. Citroni, V. Marzocchi, Inalbon M.C., M. Citroni, V. Marzocchi, C. Pieck , M. Zanuttini M. Zanuttini C. Pieck , FIQ - - UNL UNL FIQ Santa Fe - - Argentina Argentina Santa Fe

Chip Impregnation for pulping Chip Impregnation for pulping A proper A proper Penetration of liquids Penetration of liquids Diffusion of chemicals Diffusion of chemicals Both are necessary for optimal efficiency of: Chemical pulping Chemical pulping Chemimechanical pulping Chemimechanical pulping

Uniformity Uniformity The uniformity of the impregnation The uniformity of the impregnation determines determines the uniformity of the chemical the uniformity of the chemical treatment in the first stage of pulping treatment in the first stage of pulping Is essential for Is essential for the homogeneity of the pulp obtained the homogeneity of the pulp obtained

Distribution of kappa number of a kraft softwood pulp Grá áfica de fica de Gr Kappa Kappa malkov malkov number number of of individual individual fiber fiber foto foto Fluorescencia Fluorescencia Malkov, et al Malkov, et al

Flourescence on kraft fibers Flourescence on kraft fibers Fluorescence – – kappa number kappa number Fluorescence Yue Liu, Tappi J. 82(9), 1999 Yue Liu, Tappi J. 82(9), 1999

The Malkov work shows: The Malkov work shows: •A fairly broad distribution of A fairly broad distribution of • kappa of the softwood kraft pulp. kappa of the softwood kraft pulp. •Distribution can be notably Distribution can be notably • reduced when a proper reduced when a proper impregnation is applied impregnation is applied

Benefits of a proper wood Benefits of a proper wood impregnation in a kraft pulping impregnation in a kraft pulping In general it is shown in the literature that In general it is shown in the literature that it can lead to: it can lead to: • Increase in pulping yield Increase in pulping yield • •Reduction in cooking time Reduction in cooking time • •Reduction in bleaching chemical Reduction in bleaching chemical •

The alkaline impregnation The alkaline impregnation phenomenon is complex. phenomenon is complex. It implies: : It implies •Air removing Air removing • •Penetration in the longitudinal direction Penetration in the longitudinal direction • •Diffusion in all directions. Diffusion in all directions. • •Chemical reactions and wood swelling Chemical reactions and wood swelling • •Chemical modification of wood. Alkali Chemical modification of wood. Alkali • diffusion coefficient is changed diffusion coefficient is changed Issues not considered in the literature Issues not considered in the literature

Chips treated with alkali shows a Chips treated with alkali shows a impregnation front impregnation front The size of the intact core reduces with time. The size of the intact core reduces with time. Situation depends on the wood and treatment Situation depends on the wood and treatment conditions. conditions.

Alkali impregnation of hardwood in Alkali impregnation of hardwood in transverse direction transverse direction For poplar (Zanuttini et al., JPPS 2003) (Zanuttini et al., JPPS 2003) and and For poplar for eucalyptus wood (Zanuttini et al., Holz for eucalyptus wood (Zanuttini et al., Holz un Roh, 2003), it was shown: it was shown: un Roh, 2003), o C, At temperatures below 100 o C, At temperatures below 100 impregnation is a reactive diffusion impregnation is a reactive diffusion process. process.

Consumption could be as high as 6.0 % NaOH / wood Consumption could be as high as 6.0 % NaOH / wood 3,5 Original wood 3,0 o C 50 2,5 ACETYLS (%) o C 70 o C 2,0 90 1,5 1,0 Stoichiometric consumption 0,5 0,0 0,00 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 CONSUMPTION ( g NaOH / g wood ) • Deacetylation is the main reaction and is the Deacetylation is the main reaction and is the • main responsible for alkali consumption. main responsible for alkali consumption.

Mechanism Mechanism At low temperature, it was shown that: At low temperature, it was shown that: During impregnation, a reactive front During impregnation, a reactive front is established which separates an is established which separates an intact inner zone from a reacted and intact inner zone from a reacted and swollen outer zone. swollen outer zone.

Pre- -steaming and pressurized steaming and pressurized Pre impregnation impregnation • Presteaming rapidly heats the wood and the Presteaming rapidly heats the wood and the • steam produced inside chips is useful to steam produced inside chips is useful to displace the air (Malkov et al 2000). displace the air (Malkov et al 2000). • When chip is immersed in liquid under When chip is immersed in liquid under • pressure, a high liquid uptake takes pressure, a high liquid uptake takes place (Malkov et al. 2000) place (Malkov et al. 2000) • Presteaming stage and pressurized Presteaming stage and pressurized • impregnation should be considered should be considered for a for a impregnation impregnation analysis impregnation analysis

In this paper: In this paper: The pattern of the pressurized alkaline The pattern of the pressurized alkaline impregnation is analyzed: impregnation is analyzed: pine and eucalyptus pre- -steamed wood steamed wood pine and eucalyptus pre wood wood Profiles of: Profiles of: • alkali alkali • • liquid content liquid content • concentration concentration • acetyls content acetyls content • • alkali content alkali content • It is shown that the level of impregnation It is shown that the level of impregnation can be predicted for given operation can be predicted for given operation conditions conditions

Experimental Experimental

Cubes from eucalyptus wood Cubes from eucalyptus wood Cubes Cubes Outer Zone Outer Zone Inner Zone Inner Zone

Impregnation Impregnation experiences experiences A Weverk digester: A Weverk digester: • Steaming of wood Steaming of wood • samples by the samples by the liquor vapor liquor vapor •Pressurization by Pressurization by • Nitrogen Nitrogen

Positions of Weverk digester during Positions of Weverk digester during impregnation impregnation Wood Wood Samples Samples Pressure Pressure Despresurización N 2 relief relief

Procedure stages Procedure stages Preheating of liquor at 100 o o C 1) Preheating of liquor at 100 C 1) 2) Load of samples (under the digester cover) Load of samples (under the digester cover) 2) 3) Heating, air relief and steaming Heating, air relief and steaming 3) 4) Immersion in the liquor (Position 2) (Position 2) and and 4) Immersion in the liquor pressurization up to 6 Bar (N 2 ) pressurization up to 6 Bar (N 2 ) 5) Treatment under digester rotation Treatment under digester rotation 5) 6) Relief of digester (wood submerged in the liquid). Relief of digester (wood submerged in the liquid). 6) Flash in wood was avoided (Position 1) (Position 1) Flash in wood was avoided 7) Opening of digester and immersion of cubes in Opening of digester and immersion of cubes in 7) liquid Nitrogen by 2 hours. liquid Nitrogen by 2 hours. 8) Store at freezer temperature. 8) Store at freezer temperature.

Slicing of treated cubes Slicing of treated cubes Wood Wood sample is sample is still frozen still frozen Slices are weighed, and chemical analyzed Slices are weighed, and chemical analyzed

Tangential Tangential face of face of impregnated impregnated wood wood Wood vessels Wood vessels 1 cm 1 cm 1 cm

Chemical Chemical analysis of analysis of slices slices • Titration Titration • • Drying Drying • • Acetyl content by Acetyl content by • GC chromatography GC chromatography

Results Results

Results Results • For Eucalyptus and Pine For Eucalyptus and Pine • • Profiles in radial direction Profiles in radial direction • as a function of the position from de as a function of the position from de interphase interphase • Liquid content of the internal Liquid content of the internal • zone of the wood zone of the wood

Eucalyptus – – 15 minutes 15 minutes Eucalyptus ALKALI (g NaOH / L) ALKALI (g NaOH / kg) ACETYLS (x10) LIQUID (x5 g water/g) REACTION ZONE 12 REACTION INNER OUTER ZONE ZONE ZONE 10 8 6 ACETYLS 4 ALKALI 2 0 0.0 0.5 1.0 1.5 2.0 POSITION FROM THE SURFACE (mm)

Eucalyptus – – 30 minutes 30 minutes Eucalyptus ALKALI (g NaOH / L) ALKALI (g NaOH / kg) ACETYLS (x10) LIQUID (x5 g water/g) REACtION ZONE 12 REACTION INNER OUTER ZONE ZONE 10 ZONE 8 ACETYLS 6 4 ALKALI 2 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 POSITION FROM THE SURFACE (mm)

Latewood of pine pine Latewood of ALKALI (g NaOH / L) ALKALI (g NaOH / kg) ACETYLS (x10) LIQUID (x5 g water/g) REACTION ZONE 12 OUTER REACTION INNER ZONE ZONE ZONE 10 8 ACETYLS 6 4 ALKALI 2 0 0.0 0.5 1.0 1.5 2.0 2.5 POSITION FROM THE SURFACE (mm)