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Göteborg, Sweden

Nguyen T.D.H.,Chalmers University of Technology | Maschietti M.,Chalmers University of Technology | Maschietti M.,University of Aalborg | Amand L.-E.,Chalmers University of Technology | And 4 more authors.
Bioresource Technology | Year: 2014

The catalytic conversion of suspended LignoBoost Kraft lignin was performed in near-critical water using ZrO2/K2CO3 as the catalytic system and phenol as the co-solvent and char suppressing agent. The reaction temperature was varied from 290 to 370°C and its effect on the process was investigated in a continuous flow (1kg/h). The yields of water-soluble organics (WSO), bio-oil and char (dry lignin basis) were in the ranges of 5-11%, 69-87% and 16-22%, respectively. The bio-oil, being partially deoxygenated, exhibited higher carbon content and heat value, but lower sulphur content than lignin. The main 1-ring aromatics (in WSO and diethylether-soluble bio-oil) were anisoles, alkylphenols, catechols and guaiacols. The results show that increasing temperature increases the yield of 1-ring aromatics remarkably, while it increases the formation of char moderately. An increase in the yields of anisoles, alkylphenols and catechols, together with a decrease in the yield of guaiacols, was also observed. © 2014. Source

Karlsson E.,Chalmers University of Technology | Vamling L.,Chalmers University of Technology | Olausson L.,Valmet Power AB | Gourdon M.,Chalmers University of Technology
Industrial and Engineering Chemistry Research | Year: 2014

In the pulp and paper industry, the evaporation of black liquor is an important step to recover heat and chemicals. Due to a substantial amount of sodium carbonate and sodium sulfate in the black liquor, evaporators typically have to address the scaling of these water-soluble salts at concentrations above approximately 50% dry solids content. To maintain their operation, the evaporators are cleaned regularly using condensate or weak black liquor. In this paper, a model for evaporator cleaning was developed based on a dissolution model established via experimental measurements. Two new correlations for black liquor were also developed from experimental measurements: the solubility limit of sodium scales in black liquor and the density of black liquor containing additional dissolved salts. The simulations indicate high dissolution rates, meaning that the limiting step for the cleaning is the feed of free water with the wash liquid. The simulation results were insensitive to the distribution of scales, the mass transfer coefficient, and the temperature. However, the results were sensitive to the solubility limit and natural salt content for wash liquors above 30% dry solids content. © 2014 American Chemical Society. Source

Nguyen Lyckeskog H.,Chalmers University of Technology | Mattsson C.,Chalmers University of Technology | Amand L.-E.,Chalmers University of Technology | Olausson L.,Valmet Power AB | And 3 more authors.
Energy and Fuels | Year: 2016

The stability of lignin-derived bio-oil obtained from a continuous process [base (K2CO3)-catalyzed, using phenol as a capping agent] under subcritical conditions of water (25 MPa, 290-370 °C) was investigated. The lignin-derived bio-oil obtained was stored at ambient temperature for 2 years. Our results show that the base concentration in the feed solution affects the stability of this lignin-derived bio-oil during its long-term storage. It was found that, at low base concentrations (i.e., 0.4%-1.0%), the yields of all lignin-derived bio-oil fractions were relatively stable. At high base concentrations (i.e., 1.6%-2.2%), however, the yield of high-molecular-weight (high-Mw) structures increased and that of low-molecular-weight (low-Mw) structures decreased after storage. This indicated that the low-Mw materials had been polymerized to form high-Mw materials. In addition, it was found that the yield of gas chromatography-mass spectrometry (GC-MS)-identified compounds (excluding phenol) in this lignin-derived bio-oil decreased from 15% to 11%. This is probably due to the presence of solids in these lignin-derived bio-oils, which promotes the catalytic polymerization reactions, suggesting that it is beneficial to remove the solids from this lignin-derived bio-oil in order to enhance its stability. Compared to the results obtained from bio-oil derived from biomass pyrolysis, our results show that bio-oil derived from the conversion of lignin in subcritical water has better chemical stability during long-term storage. © 2016 American Chemical Society. Source

The improved method and arrangement are for cooling torrefied lignocellulosic material. By adding water in controlled amounts to the torrefied material in a grinder at exit from a roaster the entire volume of torrefied material could be cooled down to a temperature well below the critical temperature without increasing the water content of the final product.

The method is for separation of lignin from original black liquor (BL

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