| 1. |
- Abdelaziz, Omar, et al.
(författare)
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Continuous catalytic depolymerisation and conversion of industrial kraft lignin into low-molecular-weight aromatics
- 2018
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6823 .- 2190-6815. ; 8:2, s. 455-470
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Tidskriftsartikel (refereegranskat)abstract
- Base-catalysed depolymerisation of lignin using sodium hydroxide has been shown to be an effective approach towards exploiting industrial (technical) lignins within the pulp and paper industry. In the present work, a pine kraft lignin (Indulin AT) which is precipitated from black liquor of linerboard-grade pulp was depolymerised via base catalysis to produce low-molecular-mass aromatics without any organic solvent/capping agent in a continuous-flow reactor setup for the first time. The catalytic conversion of lignin was performed/screened at temperatures varying from 170 to 250 °C, using NaOH/lignin weight ratio ≈ 1 with 5 wt% lignin solids loadings for residence times of 1, 2 and 4 min, respectively, with comprehensive characterisation of substrate and produced reaction mixtures. The products were characterised using size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR) and supercritical fluid chromatography-diode array detector-tandem mass spectrometry (SFC-MS). The optimum operating conditions for such depolymerisation appeared to be at 240 °C and 30 h−1, yielding the highest concentration of low-molecular-weight phenolics below the coking point. It was also found that the depolymerised lignin products exhibited better chemical stability during long-term storage at lower temperatures (~ 4 °C).
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| 2. |
- Belkheiri, Tallal, 1985, et al.
(författare)
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Hydrothermal liquefaction of kraft lignin in sub-critical water: the influence of the sodium and potassium fraction
- 2018
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 8:3, s. 585-595
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Tidskriftsartikel (refereegranskat)abstract
- As a part of developing a hydrothermal liquefaction (HTL) process to valorise lignin, it is important to consider integration possibilities with existing infrastructures in order to obtain an overall positive economic impact. One obvious example is to integrate the HTL process with the kraft pulp mill: transport and storage costs is reduced, the temperature levels on process streams can be matched (energy integration) and the recovery/use of alkali can be made efficient. In this study, softwood kraft lignin was depolymerised using sub-critical water (623 K; 25 MPa) in a continuous, small pilot unit with a flow rate of 2 kg/h. ZrO2, K2CO3/KOH and Na2CO3/NaOH were used as catalytic system, and phenol as the capping agent. The influence of the ratio between sodium and potassium in the feed on the yield and composition of the product stream was investigated. The results showed that bio-oil, water-soluble organics (WSO) and char yields were not remarkably influenced by shifting the catalytic system from potassium to sodium. Moreover, the yields of most phenolic compounds did not change significantly when the sodium fraction was varied in the feed. The amounts of suspended solids in the bio-oil produced showed, however, a diminishing trend, (decrease from 10.8 to 3.8%) when the sodium fraction was increased in the feed, whilst the opposite trend was observed for the heavy oil, which increased from 24.6 to 37.6%.
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| 3. |
- Birru, Eyerusalem, et al.
(författare)
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Assessing the potential of energy saving in a traditional sugar canemill during steady state and transient conditions : part I: basecase plant model
- 2015
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Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6823 .- 2190-6815.
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Tidskriftsartikel (refereegranskat)abstract
- Sugar cane mills are energy intensive industries andalso have a large potential of providing surplus energy interms of heat or power. Identification of heat and mechanicallosses in sugar mills is one approach in indicating energysaving potential in sugar mills, especially in traditional mills.Such assessment of the energy flows in sugar mills needs to bedone both in steady state and transient conditions (where suddenstoppages occur). In this paper, such an approach is consideredwhere a base case plant is modeled for steady state andtransient state operations. For the transient state study, a typicalstoppage is chosen and three different scenarios aremodeled. Heat loss calculations are done for major cogenerationunits and for the amount accumulated of the surplus bagassewhen the steady state operation is estimated. The resultsof the models show that during steady state operation, thelosses related to mechanical prime movers is on the higherside as the mills and shredder are driven by steamand generatemechanical power higher than what is needed by the mills andthe shredder equipment themselves. In the transient statescenarios, where fuel oil is introduced during press mill stoppage,there is steam wasted (steam that could have been usedfor mechanical power generation) starting from the periodwhere the fuel oil is introduced until the power required duringthe stoppage is reached. The CO2 emission during the use offuel oil is also quite significant during the stoppage.
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| 4. |
- Birru, Eyerusalem, et al.
(författare)
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Energy performance comparisons and enhancements in the sugar cane industry
- 2019
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Berlin/Heidelberg. - 2190-6815 .- 2190-6823. ; 9:2, s. 267-282
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Tidskriftsartikel (refereegranskat)abstract
- In this study, energy-related operational parameters for modern and traditional (conventional) sugar mills are analyzed, with the goals of identifying improvements in energy efficiency and potential for surplus electricity export. Results show that the power- to-heat ratio of modern and traditional mills is clearly distinct, lying in the ranges of 0.3–0.5 and 0.04–0.07, respectively. Modifications under consideration for the traditional mills include the following upgrades: electric drives and higher capacity back-pressure turbine (case 1); high-pressure boiler, condensing extraction steam turbine and electric drives (case 2); and improvements in case 2 plus bagasse drying (case 3). The thermodynamic impact of these modifications shows that more power is generated as the modification becomes more advanced. Case 1 exhibits a modest increase in cogeneration efficiency (4%) as compared to the base case, while the cogeneration efficiency increase is more marked for cases 2 and 3 (21% and 31%, respectively). Surplus power was studied in a regional context, where it was found that the contribution of 19 retrofitted sugar mills in nine Brazilian regions could supply 30% or more power as compared to current installed power capacity. The economic analysis showed that levelized cost of electricity (LCOE) was lowest for case 1 (11 USD/MWh) and highest for cases 2 and 3 (58 USD/kWh).
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| 5. |
- Birru, Eyerusalem, et al.
(författare)
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Upgrading of a traditional sugar cane mill to a modern milland assessing the potential of energy saving during steady stateand transient conditions : part II: models for a modifiedcogeneration unit
- 2016
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Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6823 .- 2190-6815. ; 6:2, s. 233-245
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Tidskriftsartikel (refereegranskat)abstract
- It is known that there is a significant amount ofthermal energy used for the sugar cane industry for the purposeof power production and for use in the sugar or ethanolprocessing in cane sugar industries. Likewise, it is understoodthat there are substantial amounts of waste heat that is notbeing recovered, in particular for traditional sugar mills. Regardlessof this, energy conservation is given less considerationas compared to operational convenience due to the factthat sugar mills are self-sufficient in energy (heat and power).The identification of such potential heat loss areas (especiallyduring transient conditions) suggests the sugar mills play avital role in energy saving. In this study, a modified setup ofthe base case plant considered in part I of this paper is assessedfor its energy potential and possible major heat losses duringsteady state and transient conditions where 2-h stoppage of themill presses are considered to occur. For the modified setup,there are two major scenarios considered having two subscenarioseach. The result of the assessment showed that thesteady state assumption scenario of the modified plant (wherebagasse drying is not considered) indicated a 20 % reductionin the losses considered which resulted in a 57 % power generationincrease as compared to the steady state model of thebase case plant. It is also possible to save excess bagasse bydrying the bagasse for later use during unexpected stoppage.The carbon dioxide emission (amounting 29 t/day in case 2aof this study) that occurs during the use of fuel oil during suchstoppages will thus be avoided. The simple economic analysisshowed that it is only in case 2a where fuel oil cost is includedin the operation cost that resulted in a negative NPV. Since therest of the scenarios use bagasse as a fuel which is free, theNPV for all was positive. For the electricity price of 0.04 US$/kWh and discount rate of 15 %, the minimum paybackperiod attained is about 3 years (case 1b) where the bagassemoisture content is 30 % whereas the maximum payback periodis 6 years (case 1a) where there is no bagasse dryingconsidered.
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| 6. |
- Bär, Janosch, et al.
(författare)
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Deconstruction of hybrid poplar to monomeric sugars and aromatics using ethanol organosolv fractionation
- 2018
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Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6815 .- 2190-6823. ; 8:4, s. 813-824
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Tidskriftsartikel (refereegranskat)abstract
- Acidic ethanol organosolv fractionation of hybrid poplar was investigated to determine the impact of pretreatment conditions on the resulting biomass and lignin properties and to assess the subsequent deconstruction of the cell wall biopolymers to monomeric sugars and aromatics. It was found that increasing reaction severity (i.e., time and temperature) during the organosolv fractionation increased the rate of delignification and xylan solubilization while the lignins recovered from the liquors were found to exhibit lower degrees of polymerization. Glucose hydrolysis yields > 75% at moderate enzyme loadings (30 mg/g glucan) could be obtained for the more severe pretreatment conditions. The lignins recovered from the pretreatment liquors were subjected to fractionation using a sequential extraction with solvents of increasing polarity. It was found that the low molar mass, low polydispersity lignins increased in pretreatment liquors with increasing time and temperature and were concentrated in the methanol fraction while a high molar mass fraction was extracted with the diethyl ether. We hypothesize that the extraction of the high molar mass fraction with diethyl ether is due to partial ethyl O-alkylation of lignin hydroxyl groups during pretreatment, rendering lignins more soluble in the non-polar solvent. Finally, depolymerization of unfractionated lignins by thioacidolysis resulted in mass yields of aromatic monomers ranging from 80 to 157 mg monomer per gram of lignin and that these yields exhibited strong positive correlations to the lignin β-O-4 content, molar mass, and strong negative correlations to the pretreatment temperature.
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| 7. |
- Cardozo Rocabado, Evelyn, et al.
(författare)
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Comparison of the thermal power availability of different agricultural residues using a residential boiler
- 2016
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Ingår i: BIOMASS CONVERSION AND BIOREFINERY. - : Springer. - 2190-6815 .- 2190-6823. ; 6:4, s. 435-447
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a comparison of combustion performance, losses, and efficiency at steady-state and transient conditions for different biomass types in a residential boiler. The types of biomass used were 6 and 8 mm wood pellets, 6 mm sugarcane bagasse pellets, 6 mm sunflower husk pellets, and Brazil nut shells. The comparison in the development of the temperature in the combustion chamber during the start-up revealed that the 6 mm wood pellets ignite and propagate faster than the rest of the biomass fuels due to their smaller size compared with 8 mm wood pellets and lower ash content compared with the rest of the biomass sorts. Thermal power output and efficiencies under steady-state and transient conditions were calculated by the direct method, i.e., by measuring the heat recovery by the water boiler, and the indirect method, i.e., by measuring the heat losses. By using the indirect method, the availability of the flue gas thermal power during the start-up was seen more in detail than when the other method was applied. When comparing both methods as tools for boiler efficiency evaluation for different fuel types, the discrepancy of the resulting efficiencies between is larger when there are higher amounts of chemical losses in the boiler. Therefore, this method shows good agreement also for bagasse pellets but is, without modification, proposed not to be valid for fuels emitting higher amount of carbon monoxide (CO). Boiler efficiencies reached class 3 boilers according to EN 303-5 (> 74.8 %) for all biomass sorts.
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| 8. |
- Faisal, Abrar, et al.
(författare)
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Zeolite MFI adsorbent for recovery of butanol from ABE fermentation broths produced from an inexpensive black liquor-derived hydrolyzate
- 2018
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Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6815 .- 2190-6823. ; 8:3, s. 679-687
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Tidskriftsartikel (refereegranskat)abstract
- In this work, high-silica MFI zeolite adsorbent was evaluated for selective recovery of butanol from a real ABE (acetone, butanol, and ethanol) fermentation broth by batch adsorption measurements. The fermentation broth was produced using a hydrolyzate originating from Kraft black liquor, an internal stream in pulp mills, i.e., a low-cost substrate. The adsorbent was very selective towards butanol and butyric acid and became nearly saturated with a mixture of butanol and butyric acid with relative amounts of butanol and butyric acid depending on the pH. The presence of phenolic compounds in significant amounts in the fermentation broths, originating from the black liquor hydrolyzate, did not affect the adsorption of butanol and butyric acid.
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| 9. |
- Furusjö, Erik, 1972-, et al.
(författare)
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Thermodynamic equilibrium analysis of entrained flow gasification of spent pulping liquors
- 2018
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Ingår i: Biomass Conversion and Biorefinery. - : Springer. - 2190-6815 .- 2190-6823. ; 8:1, s. 19-31
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Tidskriftsartikel (refereegranskat)abstract
- The main goal of this work is to investigate if thermodynamic equilibrium calculations can be useful for understanding and predicting process performance and product composition for entrained flow gasification of spent pulping liquors, such as black liquor. Model sensitivity to input data is studied and model results are compared to published pilot plant data. The high temperature and the catalytic activity of feedstock alkali make thermodynamic equilibrium a better predictor of product composition than for many other types of biomass and gasification technologies. Thermodynamic equilibrium calculations can predict the flows of the main syngas and slag products with high accuracy as shown by comparison with experimental data with small measurement errors. The main process deviations from equilibrium are methane formation and sulfur distribution between gas and slag. In order to study real process deviations from equilibrium, it is very important to use consistent experimental data. Relatively small errors in the model input, primarily related to fuel composition, can lead to grossly erroneous conclusions. The model sensitivity to fuel composition also shows that the gasification process is sensitive to naturally occurring feedstock variations. Simulations of a commercial-scale gasification process show that cold gas efficiency on sulfur-free basis can reach over 80 % and that greatly improved efficiency can be obtained by reducing ballast present in the form of water or inorganics.
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| 10. |
- Göransson, Kristina, et al.
(författare)
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Internal tar/CH4 reforming in a biomass dual fluidised bed gasifier.
- 2015
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 5, s. 355-366
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Tidskriftsartikel (refereegranskat)abstract
- An internal reformer is developed for in situ catalyticreforming of tar and methane (CH4) in allothermal gasifiers.The study has been performed in the 150 kW dual fluidised bed (DFB) biomass gasifier at Mid Sweden University(MIUN). The MIUN gasifier is built for research onsynthetic fuel production. Reduction of tars and CH4 (exceptfor methanation application) in the syngas is a major challengefor commercialization of biomass fluidised-bed gasificationtechnology towards automotive fuel production. The MIUN gasifier has a unique design with an internal reformer, where intensive contact of gas and catalytic solids improves the reforming reactions. This paper presents an initial study on the internal reformer operated with and without Ni-catalytic pellets, by evaluation of the syngas composition and tar/CH4 content. A novel application of Ni-catalyst in DFB gasifiers is proposed and studied in this work. It can be concluded that the reformer with Ni-catalytic pellets clearly gives a higher H2 content together with lower CH4 and tar contents in the syngas than the reformer without Ni-catalytic pellets. The gravimetric tar content decreases down to 5 g/m3 and the CH4 content down below 6 % in the syngas. The tar content can be decreased further to lower levels, with increased gas contact to the specific surface area of the catalyst and increased catalyst surface-to-volume ratio. The new design in the MIUN gasifier increases the gasification efficiency, suppresses the tar generation and upgrades the syngas quality.
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