Valmet Power AB

Göteborg, Sweden

Valmet Power AB

Göteborg, Sweden
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Lyckeskog H.N.,Chalmers University of Technology | Mattsson C.,Chalmers University of Technology | Olausson L.,Valmet Power AB | Andersson S.-I.,Chalmers University of Technology | And 2 more authors.
Tappi Journal | Year: 2017

Accelerated aging of bio-oil derived from lignin was investigated at different aging temperatures (50°C and 80°C) and times (1 hour, 1 day, 1 week, and 1 month). The bio-oil used was produced by the hydrothermal liquefaction of kraft lignin, using phenol as the capping agent, and base (potassium carbonate and potassium hydroxide) and zirconium dioxide as the catalytic system in subcritical water. Elemental composition, molecular weight (by using gel permeation chromatography), and chemical composition (by using gas chromatography-mass spectrometry and 2D nuclear magnetic resonance [18.8 T, DMSO-d6]) of the bio-oil were measured to gain better understanding of the changes that occurred after being subjected to an accelerated aging process. The ligninderived hydrothermal liquefaction bio-oil was quite stable compared with biomass-pyrolysis bio-oil. The yield of the low molecular weight fraction (light oil) decreased from 64.1% to 58.1% and that of tetrahydrofuran insoluble fraction increased from 16.5% to 22.2% after aging at 80°C for 1 month. Phenol and phenolic dimers (Ar-CH2-Ar) had high reactivity compared with other aromatic substituents (i.e., methoxyl and aldehyde groups); these may participate in the polymerization/condensation reactions in the hydrothermal liquefaction bio-oil during accelerated aging. Moreover, the 2D heteronuclear single quantum coherence nuclear magnetic resonance spectra of the high molecular weight fraction (heavy oil) in the aged raw oil in the aromatic region showed that the structure of this fraction was a combination of phenol-alkyl patterns, and the guaiacol cross-peaks of Ar2, Ar5, and Ar6 after aging indicate that a new polymer was formed during the aging process.


Belkheiri T.,Chalmers University of Technology | Vamling L.,Chalmers University of Technology | Nguyen T.D.H.,Chalmers University of Technology | Maschietti M.,Chalmers University of Technology | And 5 more authors.
Cellulose Chemistry and Technology | Year: 2014

As part of developing a process to valorize lignin in a pulp mill with lignin separation, the depolymerisation of lignin to valuable chemicals was investigated in near-critical water. This was done by using methanol as co-solvent and hydrogen donor, phenol to suppress repolymerization (e.g. formation of char), and ZrO2 as a heterogeneous catalyst, with potassium carbonate as a co-catalyst. The reaction was carried out in a continuous flow fixed-bed reactor (500 cm3), at 280-350°C and 25MPa. An important aspect is to suppress char formation. Therefore, the char formation was studied by using different concentrations of methanol and phenol. The char yield varied between 14% and 26%. When using methanol as the only co-solvent, the char yield decreased with increasing methanol concentration. Adding phenol resulted in a further decrease. The reactor outlet consisted mainly of two liquid phases, an aqueous and an oil phase, mixed together. The chemical analysis of the aqueous phase showed the presence of mainly phenolic compounds, for instance guaiacol, catechol, phenol and cresol.


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.


Wallmo H.,Valmet Power AB | Andersson U.,Valmet Power AB | Gourdon M.,Chalmers University of Technology | Wimby M.,Valmet Power AB
Tappi Journal | Year: 2015

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105°C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%. Application: This study can be used to help assess the consequences for an evaporation plant concerning both changes in capacity and risk for fouling when evaluating a biorefinery concept, including lignin removal, at a mill. It also adds novel information to the research work on black liquor evaporation. Application: This study can be used to help assess the consequences for an evaporation plant concerning both changes in capacity and risk for fouling when evaluating a biorefinery concept, including lignin removal, at a mill. It also adds novel information to the research work on black liquor evaporation.


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.


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.


PubMed | Valmet Power AB and Chalmers University of Technology
Type: | Journal: 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 370C 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.


The method is for separation of lignin from original black liquor (BL_(IN)) and has the following phases in sequence. A first precipitation phase (PR1) for precipitation of lignin by a first acidification of the original black liquor by adding a first acid or mixture of acids (G_(1a)) followed by a first storage phase wherein precipitated lignin particles are allowed to increase in size, followed by a second precipitation phase (PR2) for precipitation of lignin by a further acidification of the original black liquor by adding a second acid or mixture of acids (G_(1b)). By retaining the acidified black liquor for at least 25 minutes in the storage phase are the precipitated lignin particles allowed to grow in size and the filterability is improved considerably.


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.

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