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  • 1.
    Anugwom, Ikenna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    Rujana, L.
    Wärnå, J.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland.
    In quest for the optimal delignification of lignocellulosic biomass using hydrated, SO2 switched DBU MEASIL switchable ionic liquid2016In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 297, p. 256-264Article in journal (Refereed)
    Abstract [en]

    In this paper, various process parameters aiming at optimal short-time-high-temperature (STHT) process were studied upon fractionation of Nordic woody biomass into its primary constituents. Highly diluted, aqueous 'SO2-switched' switchable ionic liquid (SIL) based on an alkanol amine (monoethanol amine, MEA) and an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU) was applied. The ultimate goal was to develop a more sustainable, environmentally friendly and cost efficient systems for efficient separation of the lignocellulosic fractions. One of the main products from the SIL fractionation is cellulose-rich pulp with very low lignin content, complemented with hemicelluloses. The NMR results reveal that substantial removal of lignin occurs even when relatively low amount of SIL was used. Further, a simple mathematical model describing the dissolution of the lignocellulose components (hemicellulose and lignin) and weight loss of wood as a function of time is described. Moreover, the most efficient process involved the use of SpinChem (R) rotating bed reactor while upon use of a flow through (loop) reactor, promising results were obtained at a treatment time of 4 h. Still, all the reactor systems studied gave rise to a rather low removal of hemicelluloses which mean that the solvent system is primary selective towards lignin dissolution.

  • 2. Berglund, Linn
    et al.
    Anugwom, Ikenna
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Aitomäki, Yvonne
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Oksman, Kristiina
    Switchable ionic liquids enable efficient nanofibrillation of wood pulp2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 8, p. 3265-3279Article in journal (Refereed)
    Abstract [en]

    Use of switchable ionic liquid (SIL) pulp offers an efficient and greener technology to produce nanofibers via ultrafine grinding. In this study, we demonstrate that SIL pulp opens up a mechanically efficient route to the nanofibrillation of wood pulp, thus providing both a low cost and chemically benign route to the production of cellulose nanofibers. The degree of fibrillation during the process was evaluated by viscosity and optical microscopy of SIL treated, bleached SIL treated and a reference pulp. Furthermore, films were prepared from the fibrillated material for characterization and tensile testing. It was observed that substantially improved mechanical properties were attained as a result of the grinding process, thus signifying nanofibrillation. Both SIL treated and bleached SIL treated pulps were fibrillated into nanofibers with fiber diameters below 15 nm thus forming networks of hydrophilic nature with an intact crystalline structure. Notably, it was found that the SIL pulp could be fibrillated more efficiently than traditional pulp since nanofibers could be produced with more than 30% less energy when compared to the reference pulp. Additionally, bleaching reduced the energy demand by further 16%. The study demonstrated that this switchable ionic liquid treatment has considerable potential in the commercial production of nanofibers due to the increased efficiency in fibrillation.

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  • 3. Biasi, Pierdomenico
    et al.
    Serna, Juan Garcia
    Salmi, Tapio O.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemical Engineering, Process Chemistry Centre (PCC), Laboratory of Industrial Chemistry and Reaction Engineering, Åbo Akademi University, ÅBO-TURKU, Finland.
    Hydrogen Peroxide Direct Synthesis: Enhancement of Selectivity and Production with non-Conventional Methods2013In: ICHEAP-11: 11TH INTERNATIONAL CONFERENCE ON CHEMICAL AND PROCESS ENGINEERING, PTS 1-4 / [ed] Pierucci, S, Klemes, JJ, AIDIC - associazione italiana di ingegneria chimica, 2013, p. 673-678Conference paper (Refereed)
    Abstract [en]

    The present work is part of a comprehensive study on the direct synthesis of hydrogen peroxide in different fields, from chemistry to chemical engineering. Working on the different fields of the direct synthesis gave the possibility to look at the results and the challenges from different viewpoints. Here was investigated one parameter that enhances the direct synthesis. The H-2/Pd ratio is the key parameter that has to be investigated and optimize to enhance the hydrogen peroxide direct synthesis. Two reactors were built to study deeply the H-2/Pd ratio and to demonstrate how this parameter can affect the direct synthesis both in batch and continuous reactor with non-conventional experiments/methods. 1) A batch reactor was utilized as a "starving reactor" to enhance the productivity of hydrogen peroxide and to try to keep constant the selectivity. The starving method consists in refilling the hydrogen when it is consumed in the reactor. 2) A trickle bed reactor was utilized with a gradient of catalyst along the reactor to maximize both production and selectivity of hydrogen peroxide. The distribution of the catalyst along the bed gave the possibility to significantly improve the selectivity and the production of hydrogen peroxide (up to 0.5% in selected conditions). Higher production rate and selectivity were found when the catalyst concentration decreases along the bed from the top to the bottom compared to the uniformly dispersed catalyst. Selectivity in the batch reactor was enhanced by 5% and in the continuous reactor of 10%. The non-conventional experimental methods have been found to be novelty concepts to enhance the hydrogen peroxide direct synthesis.

  • 4. Carlsson, Per
    et al.
    Ma, Charlie
    Luleå University of Technology, Energy Engineering, Division of Energy Science, SE-971 87, Luleå, Sweden.
    Molinder, Roger
    Weiland, Fredrik
    Wiinikka, Henrik
    Öhman, Marcus
    Öhrman, Olov
    Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 11, p. 6941-6952Article in journal (Refereed)
    Abstract [en]

    Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed

  • 5. Enestam, Sonja
    et al.
    Mäkelä, Kari
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hupa, Miko
    Occurrence of Zinc and Lead in Aerosols and Deposits in the Fluidized-Bed Combustion of Recovered Waste Wood. Part 2: Thermodynamic Considerations2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 4, p. 1970-1977Article in journal (Refereed)
    Abstract [en]

    In the present work, which is the second part in a series of two, multi-phase, multi-component equilibrium calculations were used to study the chemistry and deposition behavior of lead and zinc in the combustion of recovered waste wood (RWW). Particular attention was paid to the deposition behavior in different parts of the boiler under varying flue gas and material temperature conditions. In addition, the influence of fuel composition was considered by studying three different fuel compositions. The results from the calculations were compared to experimental results from two measurement campaigns, whose goal was to experimentally determine the distribution and speciation of zinc and lead compounds in aerosol particles and deposits in the fluidized-bed combustion of RWW. The results from the experimental work are presented in part 1 (10.1021/ef101478n) of this work.

  • 6.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Characterization of kiln feed limestone by dynamic heating rate thermogravimetry2016In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 147, p. 31-42Article in journal (Refereed)
    Abstract [en]

    Quicklime is a product rich in calcium oxide produced in industrial kilns. The process involves thermal decomposition of minerals with high content of calcium carbonate. The kiln feed properties vary with the geological formation from where the mineral is quarried or mined. Characterization of feed properties is necessary to achieve an optimized kiln production. In this work the decomposition of four different types of calcite ore was investigated by comparing conventional constant heating rate and dynamic heating rate thermogravimetric methods. The conclusion of this work is that the conventional method always "overshoots" the calcination temperature when continuously heating during calcination compared to the dynamic rate method that resembles the kiln by holding temperatures constant during the calcination event. This justifies the used of the dynamic rate method. By a correct experimental parameter setup the dynamic rate method can be adapted for individual kilns and feed fractions, giving new additional value to the kiln operator and increasing the high value use of limestone deposits. This new method to characterize calcination properties of kiln feed materials can be utilized in normal kiln operations and when developing new mixes of different quality limestone. The results show differences when comparing the methods and different materials even though CaCO3 is present only as calcite. In addition, the dynamic rate method is faster than the conventional method. Besides quicklime production the method can also be applied in other industries calcining limestone, such as cement clinker production.

  • 7.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Sustainability measures in quicklime and cement clinker production2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates sustainability measures for quicklime and cement clinker production. It is the aim of this thesis to contribute to the effort of creating a more sustainable modus of industrial production.

    The methods used comprises process simulations through multicomponent chemical equilibrium calculations, fuel characterization and raw materials characterization through dynamic rate thermogravimetry.

    The investigated measures relate to alternative fuels, co-combustion, oxygen enrichment, oxyfuel combustion, mineral carbonation and optimizing raw material mixes based on thermal decomposition characteristics.

    The predictive multicomponent chemical equilibrium simulation tool developed has been used to investigate new process designs and combustion concepts. The results show that fuel selection and oxygen enrichment influence energy efficiency, and that oxyfuel combustion and mineral carbonation could allow for considerable emission reductions at low energy penalty, as compared to conventional post-combustion carbon dioxide capture technologies. Dynamic rate thermogravimetry, applied to kiln feed limestone, allows for improved feed analysis with a deeper understanding of how mixing of different feed materials will affect the production processes. The predictive simulation tool has proven to be of practical value when planning and executing production and full scale campaigns, reducing costs related to trial and error.

    The main conclusion of this work is that several measures are available to increase the sustainability of the industry.

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  • 8.
    Eriksson, Matias
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Nordkalk AB, Köping, Sverige.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Characterization of ring deposits inside a quicklime producing long rotary kiln2019In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 11, p. 11731-11740Article in journal (Refereed)
    Abstract [en]

    Ring deposits are common problems in rotary kiln operations. The ring is constantly subjected to thermal and mechanical wear counteracting the growth of the ring. If the ring hardens or if the growth of the ring is too rapid the kiln needs to be shut down and the ring removed, reducing the operational time and profitability of the process. In the present study, ring deposits from a limestone fed long rotary kiln producing quicklime was sampled and characterized in detail by SEM-EDS, dynamic rate TG and XRD. This work identifies three hardening mechanisms active in the kiln, an increased densification of the ring deposits near the refractory surface, the formation of calcite and spurrite through carbonation of the ring deposits, and the intrusion of molten fuel ash and product into the refractory, resulting in a strong attachment of the deposit to the refractory surface. The work also concludes that a significant part of the ring deposit has its origin in the fuel ash, contributing to deposit mass and increasing ring growth rate.

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  • 9.
    Fagerström, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fine particle emissions and slag formation in fixed-bed biomass combustion: aspects of fuel engineering2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is a consensus worldwide that the share of renewable energy sources should be increased to mitigate climate change. The strive to increase the renewable energy fraction can partly be met by an increased utilization of different biomass feedstocks. Many of the "new" feedstocks puts stress on certain challenges such as air pollution emissions and operation stability of the combustion process. The overall objective was to investigate, evaluate, and explain the effects of fuel design and combustion control - fuel engineering - as primary measures for control of slag formation, deposit formation, and fine particle emissions during biomass combustion in small and medium scale fixed-bed appliances. The work in this thesis can be outlined as having two main focus areas, one more applied regarding fuel engineering measures and one more fundamental regarding the time-resolved release of ash forming elements, with particular focus on potassium.

    The overall conclusion related to the abatement of particle emissions and slag formation, is that the release of fine particle and deposit forming matter can be controlled simultaneously as the slag formation during fixed-bed biomass combustion. The methodology is in this perspective denoted “fuel engineering” and is based on a combined approach including both fuel design and process control measures. The studies on time-resolved potassium release showed that a Macro-TG reactor with single pellet experiments was a valuable tool for studying ash transformation along the fuel conversion. The combination of dedicated release determinations based on accurate mass balance considerations and ICP analysis, with phase composition characterization by XRD, is important for the understanding of potassium release in general and time-resolved data in particular. For wood, the results presented in this work supports the potassium release mechanism from "char-K" but questions the previously suggested release mechanism from decomposition of K-carbonates. For straw, the present data support the idea that the major part of the potassium release is attributed to volatilization of KCl. To further explore the detailed mechanisms, the novel approach developed and applied in this work should be complemented with other experimental and analytical techniques.

    The research in this thesis has explored some of the challenges related to the combined phenomena of fuel conversion and ash transformation during thermochemical conversion of biomass, and has contributed with novel methods and approaches that have gained new knowledge to be used for the development of more effective bioenergy systems.

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  • 10.
    Fagerström, Jonathan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Dan, Boström
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fuel conversion of large samples in a thermogravimetric analyzer set-up: method description and applications2011In: 19th European Biomass Conference and Exhibition: From Research to Industry and Markets, 2011Conference paper (Refereed)
  • 11. Fatehi, Hesameddin
    et al.
    Qu, Zhechao
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Bai, Xue-Song
    Effect of Volatile Reactions on the Thermochemical Conversion of Biomass Particles2017In: 8TH INTERNATIONAL CONFERENCE ON APPLIED ENERGY (ICAE2016) / [ed] Yan, J Sun, F Chou, SK Desideri, U Li, H Campana, P Xiong, R, ELSEVIER SCIENCE BV , 2017, Vol. 105Conference paper (Refereed)
    Abstract [en]

    A numerical and experimental study on the conversion of a biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the biomass pyrolysis. The numerical domain consists of a particle and its surrounding and the model considers detailed chemical kinetic mechanism for reaction of pyrolysis products. A detailed pyrolysis model is employed which provides the composition of pyrolysis products. The effect of gas phase reaction on the conversion time and temperature of the particle is analyzed and it was shown that the gas phase reactions results in shorter pyrolysis time. H2O mole fraction and temperature above a biomass pellet from wheat straw (WS) and stem wood (SW) were experimentally measured using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The TDLAS data were used to validate the numerical model developed for biomass conversion. The results showed that by considering the gas phase reactions a good agreement between the measurement and the model prediction for mass loss and temperature can be achieved. For H2O mole fraction on top of the particle, on the other hand, some discrepancy between the model prediction and the experimental data was observed. Nevertheless, the difference in H2O mole fraction would be much larger by neglecting the gas phase reaction at the particle boundary.

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  • 12. Fatehi, Hesameddin
    et al.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Bai, Xue-Song
    Gas phase combustion in the vicinity of a biomass particle during devolatilization: model development and experimental verification2018In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 196, p. 351-363Article in journal (Refereed)
    Abstract [en]

    A numerical and experimental study on the devolatilization of a large biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the conversion of the particle and on the temperature and species distribution at the particle vicinity. A global chemical kinetic mechanism and a detailed reaction mechanism are considered in a one dimensional numerical model that takes into account preferential diffusivity and a detailed composition of tar species. An adaptive moving mesh is employed to capture the changes in the domain due to particle shrinkage. The effect of gas phase reactions on pyrolysis time, temperature and species distribution close to the particle is studied and compared to experiments. Online in situ measurements of average H2O mole fraction and gas temperature above a softwood pellet are conducted in a reactor using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The results show that the volatile combustion plays an important role in the prediction of biomass conversion during the devolatilization stage. It is shown that the global reaction mechanism predicts a thin flame front in the vicinity of the particle deviating from the measured temperature and H2O distribution over different heights above the particle. A better agreement between numerical and experimental results is obtained using the detailed reaction mechanism, which predicts a wider reaction zone.

  • 13.
    Gao, Qiuju
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edo, Mar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, Sylvia H.
    Collina, Elena
    Rudolfsson, Magnus
    Gallina, Marta
    Oluwoye, Ibukun
    Altarawneh, Mohammednoor
    Dlugogorski, Bogdan Z.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of PCDDs and PCDFs in the torrefaction of biomass with different chemical composition2017In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, p. 126-133Article in journal (Refereed)
    Abstract [en]

    Torrefaction is a thermal pre-treatment technology used to refine biomass, mainly for energy production purposes. However, there is currently a lack of information on the potential formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the torrefaction process. In this study, torrefaction was conducted using five different types of feedstock: stemwood, bark, wood from a discarded telephone pole, cassava stems and particle board. The feedstock as well as the torrefied biomass (chars) and the volatiles (non-condensable and condensable) generated during torrefaction were analyzed for PCDDs and PCDFs. PCDD concentrations in the torrefaction products were about 2-5 fold of those in the feedstocks. Torrefaction of particle board resulted in extensive formation of PCDDs (7200 ng kg(-1)) compared to the other four feedstocks (13-27 ng kg(-1)). Examination of the homologue profiles suggested that the observed PCDDs in the torrefaction products partly originated from new formation and partly physical transformation from volatilization and re-condensation of PCDDs present in the feedstock. Dechlorination of highly chlorinated compounds (HpCDD and OCDD) in the feedstock to form less chlorinated PCDDs was also observed. Compared to PCDDs, the net formation of PCDFs in the torrefaction process was low, except for the telephone pole sample, for which a dramatic increase (44-fold) of PCDFs was observed. PCDDs and PCDFs were mainly retained in the chars, accounting for 76-96% and 39-74% of the total concentration, respectively. It was also found that the highly chlorinated congeners tended to be retained in the chars, whereas the less chlorinated ones were predominantly volatilized into the gas phase.

  • 14. Gavilà, Llorenç
    et al.
    Constantí, Magda
    Medina, Francisco
    Pezoa-Conte, Ricardo
    Anugwom, Ikenna
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lactic acid production from renewable feedstock: fractionation, hydrolysis, and fermentation2018In: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 2, no 3, article id 1700185Article in journal (Refereed)
    Abstract [en]

    In this paper, an integrated fractionation with a switchable ionic liquid (SIL), pulp hydrolysis, and lactic acid fermentation is carried out. For this, SO2-swithced SIL is used for fractionation of sugar cane (Saccharum officinarum) bagasse and giant cane (Arundo donax, AD). SIL is able to extract ≈2/3 of lignin when relatively large wood chips (≈4 mm) are used without any mechanical agitation and just 1 h of treatment time for AD. Furthermore, SIL reuse is successfully demonstrated for four runs. Subsequently, the produced pulps are hydrolyzed within 15 min in a microwave reactor, producing a glucose rich hydrolysates. Finally, these hydrolysates are used as a carbohydrate source for Lactobacillus delbrueckii fermentation, which selectively transform all glucose present into optically pure D-lactic acid. Hence, the whole chain for lactic acid production from biomass is successfully demonstrated.

  • 15.
    Golets, Mikhail
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Heterogeneously Catalyzed Valorization of Monoterpenes to High Value-Added Chemicals2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A potential industrial process is profitable only if it is successfully implemented by the continuously developing chemical industry. Throughout last decades heterogeneous catalysis has opened doors to the creation of various know-how products which previously were considered unfeasible. Moreover, the use of heterogeneous catalysts allows improving existing processes to shift towards more ecological and cost efficient practices. In particular, polymer or fuel compounds could be eco-friendly produced from wood extractives, as an alternative to the conventional oil resources. This goal becomes even more attractive in light of the upcoming peak-oil.

    In the Nordic pulping industry turpentine is widely available as a tonnage by-product. Despite its interesting properties and promising application possibilities this fraction is commonly burned in the recovery boilers for energy. Although the chemical composition of turpentine depends strongly on the specific pulping process, α-pinene is the predominant compound and as such most studied. The general message of this thesis is the successful implementation of the heterogeneous catalysts in one-pot value-added upgrading of crude turpentine and specific terpenes, particularly α-pinene. Concepts allowing the production of fragrances, resins, plastics and pharmaceutical compounds are presented in the current study. Both commercial (Amberlyst 70) and self-prepared (Me/Al-SBA-15 or TiO2) catalysts were studied in several reactions including: acetoxylation, isomerization, dehydroisomerisation and oxidation. Both commercially purified α-pinene and crude thermo-mechanical turpentine were used as raw materials in the catalytic one-pot synthesis of value-added compounds.

    The experiments were performed in both batch and continuous reactor systems depending on the studied reaction. Successful results were obtained in case of several reactions. As an example, upon acetoxylation of α-pinene valuable fragrances – α-terpinyl and bornyl acetates – were produced with yields of 35 and 40 wt-%, respectively. Furthermore, in the dehydroisomerisation reaction of α-pinene, a yield of around 80 wt-% of an important fragrance, solvent and plastics precursor, ρ-cymene, was obtained. In the last case, thermo-mechanical turpentine was also successfully utilized. Still, some α-pinene oxidation tests leading to α-pinene oxide and verbenone fragrances were also carried out. Upon this study, further oxidation of ρ-cymene lead to the formation of ρ-methyl-acetophenone, a product essential for perfumery, pharmaceutical and pesticide industry as well as a potent polymer precursor. In addition, isomerization reactions were performed. Additionally, the catalytic materials were thoroughly characterized and analyzed.

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    Heterogeneously Catalyzed Valorization of Monoterpenes to High Value-Added Chemicals
  • 16.
    Haglund, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Spinnel, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A modular approach to pressurized liquid extraction with in-cell clean-up2010In: LC GC Europe, ISSN 1471-6577, Vol. 23, no 6, p. 292-301Article in journal (Refereed)
    Abstract [en]

    A new concept for the extraction of solid samples has been developed. The popular pressurized liquid extraction (PLE) technique has been modified so that the extraction cell can be divided, which greatly increases the flexibility and versatility of this technique. The system uses simple adaptors to couple commercially available extraction cells, which may be loaded with either sample or adsorbent(s). These segmented extraction cells make it possible to selectively retain analytes or matrix to achieve simultaneous extraction and clean-up or fractionation. The ultimate aim is to perform simultaneous extraction and clean-up and obtain a purified extract that is ready for instrumental analysis, all in line with current trends in analytical chemistry to automate and streamline the analytical procedures to reduce the analysis costs, solvent consumption, manual labour and increase the quality of analysis. Selected modes of operations are presented and a few recent environmental applications of modular PLE are reviewed.

  • 17.
    Haglund, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Spinnel, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A modular approach to pressurized liquid extraction with in-cell clean-up2010In: LCGC Asia Pacific, ISSN 1754-2715, Vol. 13, no 2, p. 6-12Article in journal (Refereed)
    Abstract [en]

    A new concept for the extraction of solid samples has been developed. The popular pressurized liquid extraction (PLE) technique has been modified so that the extraction cell can be divided, which greatly increases the flexibility and versatility of this technique. The system uses simple adaptors to couple commercially available extraction cells, which may be loaded with either sample or adsorbent(s). These segmented extraction cells make it possible to selectively retain analytes or matrix to achieve simultaneous extraction and clean-up or fractionation. The ultimate aim is to perform simultaneous extraction and clean-up and obtain a purified extract that is ready for instrumental analysis, all in line with current trends in analytical chemistry to automate and streamline the analytical procedures to reduce the analysis costs, solvent consumption, manual labour and increase the quality of analysis. Selected modes of operations are presented and a few recent environmental applications of modular PLE are reviewed.

  • 18.
    Hagman, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Perstorp Specialty Chemicals AB.
    Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler: ash transformation, availability and process improvements2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The direct variable costs for heat and electricity production based on solid biomass fuel combustion is approximately 3-5 times lower than the costs in a fossil fuel-oil based boiler in Sweden. In addition waste derived biomass fuels are typically much cheaper than biomass not classified as waste. The introduction of the waste derived fuels; wastewater treatment sludge, demolition wood, and animal waste in a 50MWth circulating fluidized bed (CFB) biomass boiler located in Perstorp, Sweden, led to rapid deposit buildup in superheaters, heavy ash accumulation in economizers and failing boiler tubes and vortex finders that forced frequent boiler shutdowns. This in turn increased the use of expensive oil (fossil fuel) in backup boilers and the CO2 footprint of the on-site energy conversion system. This work aims to increase the general mechanistic understanding of combustion systems using complex fuels, and includes: A mapping of the boiler failure and preventive maintenance statistics; elemental composition analysis of ash, deposits and fuel fractions; flue-gas composition measurements; chemical speciation analysis; an attempt to describe the overall ash transformation reactions and mass balance throughout the combustion process. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used to analyze the elemental composition of ash and deposits. The SEM-EDS results were used together with data from X-ray powder diffraction (XRD) analysis, thermodynamic phase data, and equilibrium calculations in an attempt to quantify the crystalline phases and the overall ash transformation of the process. Based on the findings concerning ash transformation and the failure statistics, it has been possible to identify generic key parameters regarding boiler design and process parameters, enabling major improvements of the CFB boiler availability, a lower overall energy conversion cost and a reduced CO2 footprint.

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    Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler
  • 19.
    Hagman, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Co-firing complex biomass in a CFB boiler: ash transformation, corrosion control and materials selection2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The effects of greenhouse gas net emissions on global warming, stricter legislation on waste handling, and the pursuit of ever cheaper heat- and power production are all important factors driving the introduction of complex fuels in incineration plants. However - without fundamental knowledge regarding ash transformation, corrosion control, and materials selection – this introduction of potentially economically and environmentally beneficial fuels, might instead cause economic loss and environmentally adverse effects.

    The present work is a contribution to the transition from today's CO2 net generating energy conversion system, to a more environmentally friendly and cost-efficient one. This is done using scientific methods to generate knowledge concerning mechanisms of ash transformation, corrosion control, and materials selection, in a co-fired industrial scale circulating fluidized bed (CFB) boiler, using a novel and biomass-based fuel mix, rich in Na, K, Cl, N, S, P, Ca and Si. Fuel fractions, ashes, flue gas, deposits, and construction material samples have been collected and analyzed using various techniques, including scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray Diffraction (XRD). The experimental results have been evaluated and interpreted using chemical equilibrium calculations.

    The results of this work include:

    1) An analysis of; the failure and preventive maintenance statistics of the industrial scale CFB boiler at hand; the elemental composition of boiler ashes and deposits, the flue gas composition and elemental composition of a multitude of fuel fractions; correlations between boiler design, operational parameters, elemental composition of deposits and boiler availability; a boiler elemental mass balance revealing details regarding deposit buildup mechanisms; properties of the fly ash relevant to flue gas filter design; and findings regarding the nitrogen chemistry of the novel and nitrogen-rich fuel mix.

    2) Speciation and description of the overall ash transformation and fireside alloy interaction, enabling the implementation of on-line corrosion control which significantly inhibits superheater and dew-point corrosion in the boiler; and, an equation describing the sulfation potential of the fuel mix, as a result of the direct and indirect interactions between all major ash-forming elements.

    3) A literature review relevant for the co-fired CFB cyclone vortex finder alloy selection and corrosion at 880 °C; An alloy selection study including long term exposures of several commercially available alloys identifying materials that are more than twice as cost-efficient as the often used alloy 253MA; a suggestion of novel methods for both systematic comparison of heavily degraded alloys, and for alloy service-life estimations; a detailed analysis of heavily degraded alloys 310S, 800H/HT and 600, identifying the driving corrosion mechanisms of the VF alloy degradation, including aspects of how the alloy internal mass transport and fireside surface interaction develops over time.

    The knowledge gained during this project has been used in the improvement work of the Perstorp 50 MWth CFB boiler, improving the boiler availability with 7 %, reducing the overall energy conversion costs with around 1.7 MEUR/year.

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  • 20.
    Holmgren, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Strandberg, Anna
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Wagner, David R.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Molinder, Roger
    Energitekniskt Centrum, Piteå.
    Wiinikka, Henrik
    Energitekniskt Centrum, Piteå.
    Umeki, Kentaro
    Luleå Technical University.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Size, Shape and Density Changes of Biomass Particles during Devolatilization in a Drop Tube Furnace2014In: Impacts of Fuel Quality on Power Production October 26 –31, 2014, Snowbird, Utah, USA, 2014Conference paper (Other academic)
  • 21. Horacek, J.
    et al.
    St'avova, Gabriela
    Hora, Lukas
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akad Univ, Proc Chem Ctr, Ind Chem & React Engn, FIN-20500 Turku, Finland.
    Kubicka, David
    Lignin transformations to chemicals2013In: Proceedings of the 1st INTERNATIONAL CONFERENCE ON CHEMICAL TECHNOLOGY / [ed] Kalenda, P., Lubojacky, J., Czech Chemical Society , 2013, p. 382-388Conference paper (Refereed)
    Abstract [en]

    Sodium lignosulfonate was decomposed at 320 degrees C and 130 bar over various catalysts. Zeolites Beta modified with 0.5 % of Pt showed important effect of Al content in the support on product yields. Alumina-supported NiO was also found as active in lignosulfonate decomposition to guaiacol: Moreover, the contact time of substrate with the active centers was identified as the key reaction factor in lignosulfonate decomposition. Model compounds of lignin decomposition were hydrodeoxygenated at 180 degrees C and 5 MPa over Pt modified zeolites Beta. Dealuminated zeolite was found as more active in phenol conversion than zeolite with similar Si/Al ratio obtained by direct synthesis. Reactivity of cresols increased in order m>o>p for catalyst with higher Si/Al ratio, decrease of Al content resulted in lower reactivity of cresols and change of reactivity order of isomers to o>m>p.

  • 22.
    Håkansson, Katarina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordwaeger, Martin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Ingemar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Svanberg, Martin
    Logistics and Transportation, Chalmers University of Technology.
    Process and system integration aspects of biomass torrefaction2010In: 18th European Biomass Conference and Exhibition: Proceedings, 2010Conference paper (Other academic)
    Abstract [en]

    The pre-treatment method torrefaction has been shown to significantly improve biomass fuel characteristics such as energy density, moisture content, milling energy, feeding and hydrophobic properties. These improvements establish torrefaction as a key process in facilitating an expanding market for biomass raw materials. Most of the previous work has focused on evaluating and optimizing the torrefaction process alone. However, to fully explore the maximum energy/exergy and cost efficiency of biomass torrefaction, the entire fuel supply chain and site specific systems must be considered; including logistics, scale and integration with other processes. The present work in progress aims to develop a model that incorporates optimization of the biomass supply chain and process integration systems together with the torrefaction process in order to avoid sub-optimization.

  • 23.
    Håkansson, Katarina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Olofsson, Ingemar
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Persson, Kristoffer
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Torrefaction and Gasification of Hydrolysis Residue2008In: 16th European Biomass Conference and Exhibition: Proceedings, 2008Conference paper (Other academic)
    Abstract [en]

    When producing ethanol from lignocellulosic material using hydrolysis combined with fermentation, a large amount of residue consisting of mainly lignin is generated. A significant amount of energy is retained in this residue which may be utilised as a measure for the process to become economically viable. One possibility is as fuel in a gasification process for synthesis gas production, improving the fuel yield and the overall plant efficiency. Furthermore, the pre-treatment method torrefaction has been shown to significantly improve biomass fuel characteristics such as energy density, moisture content, feeding and hydrophobic properties, as well as significantly facilitate particle size reduction. Therefore, the process chain from hydrolysis residue to synthesis gas was investigated and demonstrated in the present work through bench-scale experiments in a batch torrefaction reactor and a bubbling fluidised bed gasifier. The results from the torrefaction work confirmed the improved fuel characteristics and the effects of process variables were evaluated by factorial designed experiments. The torrefaction residence time was identified as the most influential variable. The results from reactivity tests and gasification experiments indicate that hydrolysis residue and corresponding torrefied residue are suitable for synthesis gas production, with some improved feedstock handling characteristics for the latter.

  • 24.
    Hökfors, Bodil
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Phase chemistry in process models for cement clinker and lime production2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The goal of the thesis is to evaluate if developed phase chemical process models for cement clinker and lime production processes are reliable to use as predictive tools in understanding the changes when introducing sustainability measures.

    The thesis describes the development of process simulation models in the application of sustainability measures as well as the evaluation of these models. The motivation for developing these types of models arises from the need to predict the chemical and the process changes in the production process, the impact on the product quality and the emissions from the flue gas.

    The main chemical reactions involving the major elements (calcium, silicon, aluminium and iron) are relatively well known. As for the minor elements, such as sodium and potassium metals, sulphur, chlorine, phosphorus and other trace elements, their influence on the main reactions and the formation of clinker minerals is not entirely known. When the concentrations of minor and trace elements increase due to the use of alternative materials and fuels, a model that can accurately predict their chemistry is invaluable. For example, the shift towards using less carbon intensive fuels and more biomass fuels often leads to an increased phosphorus concentration in the products.

    One way to commit to sustainable development methods in cement clinker and lime production is to use new combustion technologies, which increase the ability to capture carbon dioxide. Introducing oxy-fuel combustion achieves this, but at the same time, the overall process changes in many other ways. Some of these changes are evaluated by the models in this work.

    In this thesis, a combination of the software programs Aspen Plus™ and ChemApp™ constitutes the simulation model. Thermodynamic data from FACT are evaluated and adjusted to suit the chemistry of cement clinker and lime.

    The resulting model has been verified for one lime and two cement industrial processes.

    Simulated scenarios of co-combustion involving different fuels and different oxy-fuel combustion cases in both cement clinker and lime rotary kiln production are described as well as the influence of greater amounts of phosphorus on the cement clinker quality.

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  • 25.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Viggh, Erik
    Backman, Rainer
    On the phase chemistry of Portland cement clinker2015In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 27, no 1, p. 50-60Article in journal (Refereed)
    Abstract [en]

    This paper describes the formation of a phosphorous belite solid solution and its impact on alite formation. A sub-solidus phase relation for the ternary system silicon dioxide–calcium oxide–phosphorus pentoxide (SiO2–CaO–P2O5) is reported. The ternary system is based on Rietveld refinements of X-ray diffraction patterns from experimental tests. The overall picture is based on known phase diagrams, relevant Rietveld refinements models, stoichiometric relationships as a function of increasing phosphorus pentoxide concentration and vacancy theories for solid solutions of phosphate belites. A tool is developed for predicting the chemistry of the product as well as the chemistry during heating when producing Portland cement clinker. A thermodynamic database for phase chemistry calculations of clinkering reactions has been created and evaluated. Suitable compounds and solution species have been selected from the thermochemical database included in FactSage software. Some solution compositions have been uniquely designed to allow for the proper prediction of the cement clinker chemistry. The calculated results from the developed database for heating raw materials in cement clinker production and cooling of the product are presented in this paper. The calculated results provide a good prediction of the phases and quantities formed during heating and non-equilibrium cooling. The prediction of the amounts of alite, belite and aluminoferrite phases in the product according to the Scheil method is good. The temperature interval for the existence of all of the major phases is relevant. The thermodynamic data for a solution phase of alite with substituting ions of primarily magnesium oxide and phosphorus pentoxide would improve the predictability of the developed database.

  • 26.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Res & Dev, Heidelberg Cement Grp, Heidelberg, Germany.
    Eriksson, Matias
    Nordkalk Oy Ab, FIN-21600 Pargas, Finland.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Åbo Akad Univ, Proc Chem Res Grp, Turku, Finland.
    Improved Process Modeling for a Lime Rotary Kiln Using Equilibrium Chemistry2012In: Journal of engineering technology, ISSN 0747-9964, Vol. 29, no 1, p. 8-18Article in journal (Refereed)
    Abstract [en]

    This article describes an improved process model for simulation of the manufacturing process of lime in a rotary kiln. The model simulates ideal behavior of complex chemical systems with an assumed homogenous mixing without time-dependent factors. It is a totally predictive model that excludes the empirical parameters. The model is a chemical phase equilibrium model that calculates the final product in a non-equilibrium mode, according to established methods. The phase chemistry is among the most complex found in the literature for lime manufacturing. The thermodynamic data used in the model is based on 11 components (Ca, Si, Al, Fe, K, S, Cl, C, H, O and N). The fuel has an important role in the lime manufacturing process. Special attention is required since it is fed directly into the process via the burner and can influence the process and final product. In the model, the fuel is defined in order to have it behave in a realistic way, and operational data from a full scale lime plant verify the simulation results. The simulated amounts of gas and solids correlate well with operational data. The predicting chemical composition of the product needs improvement by adding more system components and their related compounds to the thermodynamic database. Simulation results from co-combustion of coal and processed waste based fuel oil that it is a versatile tool for predicting product quality and amount, temperature profiles of the rotary kiln, and exhaust gas composition and amount.

  • 27.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Stockholm, Sweden.
    Eriksson, Matias
    NorFraKalk, Verdal, Norway.
    Viggh, Erik
    Cementa AB, Malmö, Sweden.
    Modelling the cement process and cement clinker quality2014In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 26, no 6, p. 311-318Article in journal (Refereed)
    Abstract [en]

    This paper presents a recently developed simulation model that can be used as a tool for evaluating sustainable development measures for cement and lime production processes. Examples of such measures are introducing new combustion technologies such as oxy-fuel combustion, using biomass fuel and using alternative materials in the raw material feed. One major issue when introducing process changes is the need to maintain product quality. In some ways, oxygen-enriched air combustion resembles oxy-fuel combustion. The model results were validated and found to be consistent with full-scale operational data for normal running conditions and for a full-scale test with oxygenenriched air. The model shows, for example, that with an additional 1500 m3/h of oxygen, fuel addition at the calciners can increase up to 108% and the raw material feed rate can increase up to 116% for a process with a raw meal feed of 335.5 t/h.

  • 28.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Stockholm, Sweden.
    Viggh, Erik
    Cementa AB, Malmö, Sweden.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. NorFraKalk, Verdal, Norway.
    Simulation of oxy-fuel combustion in cement clinker manufacturing2015In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 27, no 1, p. 42-49Article in journal (Refereed)
    Abstract [en]

    A thermodynamic process model is used as an evaluation tool. Full oxy-fuel combustion is evaluated for circulation of 20–80% of flue gases to the burn zone of a rotary kiln. The full oxy-fuel combustion simulations exhibit altered temperature profiles for the process. With 60% recirculation of flue gases, the temperature in the burn zone is comparable to the reference temperature, and carbon dioxide concentration in the flue gases increases from 33 to 76%. If water is excluded, carbon dioxide concentration is 90%. The partial oxy-fuel combustion method is evaluated for 20 and 40% recirculation of flue gases from one cyclone string to both calciners. Fuel and oxygen feed to the burning zone and calciners are optimised for the partial oxy-fuel scenario. The lowest specific energy consumption is desired while maximising the amount of carbon dioxide theoretically possible to capture. By introducing partial oxy-fuel combustion with 20% recirculation of flue gases in the carbon dioxide string, total carbon dioxide emissions increases by 4%, with 84% possible to capture. Within the limits of the model, the introduction of full oxy-fuel and partial oxyfuel combustion is possible while maintaining product quality. When simulating partial oxy-fuel combustion, the energy consumption will increase even when no power consumption for the production of oxygen is included.

  • 29.
    Hökfors Wilhelmsson, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Viggh, Erik O.
    Cementa AB, Limhamn, Sweden.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A predictive chemistry model for the cement process2008In: Zement, Kalk, Gips International: ZKG international, ISSN 0949-0205, Vol. 61, no 7, p. 60-70Article in journal (Other academic)
    Abstract [en]

    A tool has been developed that enables prediction of the chemistry in cement production with thermodynamic phase equilibrium calculations. Reactions in gas, solid and liquid phases are calculated in the process from preheating tower, including exhaust gas cleaning, through rotary kiln, clinker cooler and ends at the output of clinker. The simulated values are compared to measured or calculated data from a full scale plant. This is a cement plant producing 2000 t clinker per day using both traditional and alternative fuels. The chemistry model shows good agreement especially on material chemistry at various places in the process and on composition of the clinker. A new way to define fuels is used and is straightforward and reliable. In the future work the model has to be improved and more elements are to be added to the thermodynamic database.

  • 30. Jogi, Ramakrishna
    et al.
    Mäki-Arvela, Päivi
    Virtanen, Pasi
    Kumar, Narendra
    Hemming, Jarl
    Russo, Vincenzo
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lestander, Torbjörn A.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Understanding the formation of phenolic monomers during fractionation of birch wood under supercritical ethanol over iron based catalysts2020In: Journal of the Energy Institute, ISSN 1743-9671Article in journal (Refereed)
    Abstract [en]

    The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO2, respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results.

  • 31. Jogi, Ramakrishna
    et al.
    Mäki-Arvela, Päivi
    Virtanen, Pasi
    Kumar, Narendra
    Hemming, Jarl
    Smeds, Annika
    Lestander, Torbjörn A.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Biocrude production through hydro‐liquefaction of wood biomass in supercritical ethanol using iron silica and iron Beta zeolite catalysts2019In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 94, no 11, p. 3736-3744Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: In the production of biofuels from lignocellulosic material, biocrude plays a key role. The present work deals with the biocrude production through hydrothermal liquefaction (HTL) of birch wood in supercritical ethanol over 5 wt. % Fe‐H‐Beta‐150 (SiO2 to Al2O3 ratio of 150) or 5 wt. % Fe‐SiO2 catalyst.

    RESULTS: The liquid and solid products were characterized with various analytical techniques such as GC‐MS, GC‐FID, SEC, ICP‐MS, p‐XRD, SEM, and solid‐state 13C MAS NMR respectively. The results revealed that 5 wt. % Fe‐H‐Beta‐150, a strongly Brønsted acidic catalyst, enhanced the biocrude formation when compared with a non‐acidic 5 wt. % Fe‐SiO2 catalyst. Hemicellulose and lignin degradation occurred resulting in formation of mainly sugars, acids‐esters and phenolic compounds in liquid phase. The gaseous atmosphere of hydrogen also enhanced the degradation of biomass. The biocrude yield from birch was 25 wt. % over 5 wt. % Fe‐H‐Beta‐150. The Brønsted acidic catalyst gave higher dissolution efficiency and its clear catalytic effect was observed in comparison to non‐acidic 5 wt. % Fe‐SiO2. The degradation level of lignin in presence of 5 wt. % Fe‐H‐Beta‐150 was high 68 wt. % aromatic products were formed, while only 38 wt. % was obtained with 5 wt. % Fe‐SiO2.

    CONCLUSIONS: Hydrogen atmosphere enhances the fractionation of birch wood when compared to argon atmosphere. 5 wt. % Fe‐H‐Beta‐150 catalyst enhanced very strongly the degradation of hemicellulose and lignin in biomass to sugars and acid‐esters as well as phenolic compounds, respectively compared to the non‐acidic 5 wt. % Fe‐SiO2 catalyst.

  • 32.
    Khokarale, Santosh G.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, FI-20500 Åbo - Turku, Finland.
    Metal free synthesis of ethylene and propylene carbonate from alkylene halohydrin and CO2 at room temperature2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 58, p. 34023-34031Article in journal (Refereed)
    Abstract [en]

    Herein we describe a metal free and one-pot pathway for the synthesis of industrially important cyclic carbonates such as ethylene carbonate (EC) and propylene carbonates (PC) from molecular CO2 under mild reaction conditions. In the actual synthesis, the alkylene halohydrins such as alkylene chloro- or bromo or iodohydrin and organic superbase, 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) reacted equivalently with CO2 at room temperature. The syntheses of cyclic carbonates were performed in DMSO as a solvent. Both 1,2 and 1,3 halohydrin precursors were converted into cyclic carbonates except 2-bromo- and iodoethanol, which were reacted equivalently with DBU through n-alkylation and formed corresponding n-alkylated DBU salts instead of forming cyclic carbonates. NMR analysis was used to identify the reaction components in the reaction mixture whereas this technique was also helpful in terms of understanding the reaction mechanism of cyclic carbonate formation. The mechanistic study based on the NMR analysis studies confirmed that prior to the formation of cyclic carbonate, a switchable ionic liquid (SIL) formed in situ from alkylene chlorohydrin, DBU and CO2. As a representative study, the synthesis of cyclic carbonates from 1,2 chlorohydrins was demonstrated where the synthesis was carried out using chlorohydrin as a solvent as well as a reagent. In this case, alkylene chlorohydrin as a solvent not only replaced DMSO in the synthesis but also facilitated an efficient separation of the reaction components from the reaction mixture. The EC or PC, [DBUH][Cl] as well as an excess of the alkylene chlorhydrin were separated from each other following solvent extraction and distillation approaches. In this process, with the applied reaction conditions, >90% yields of EC and PC were achieved. Meanwhile, DBU was recovered from in situ formed [DBUH][Cl] by using NaCl saturated alkaline solution. Most importantly here, we developed a metal free, industrially feasible CO2 capture and utilization approach to obtain EC and PC under mild reaction conditions.

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  • 33. Kocík, Jaroslav
    et al.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bourajoini, Hasna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pham, Tung Ngoc
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Faculty of Science and Engineering, Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Hájek, Martin
    Čapek, Libor
    Screening of active solid catalysts for esterification of tall oil fatty acids with methanol2017In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 155, no 1, p. 34-38Article in journal (Refereed)
    Abstract [en]

    The paper is focused on the description of the activity/selectivity of mesoporous silica based materials loaded with various types of active species in the esterification of tall oil free fatty acids. The metals such as aluminium, molybdenum, gallium and zinc, including their combinations were impregnated on the mesoporous silica, which was tested in esterification reaction. All these catalysts preserved its tall oil free fatty conversion in the first and the second catalytic cycles. However, while only insignificant amount of gallium or molybdenum was lost from the solid catalyst into the liquid phases, zinc leached from every studied solid catalyst. In contrast to impregnated gallium on mesoporous silica, which exhibited higher acidity and higher tall oil free fatty acids conversion in the first catalytic cycle, but its value was not preserved in the second catalytic test.

  • 34.
    Konwar, Lakhya Jyoti
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mäki-Arvela, Päivi
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    SO3H-Containing Functional Carbon Materials: Synthesis, Structure, and Acid Catalysis2019In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 119, no 22, p. 11576-11630Article in journal (Refereed)
    Abstract [en]

    The “sulfonated carbons” are a new class of metal-free solid protonic acids characterized by their unique carbon structure and Brønsted acidity (−H0 = 8–11) on par to concentrated H2SO4. These carbon materials covalently functionalized with SO3H groups via C–PhSO3H or C–SO3H linkages can act as versatile water-tolerant solid acids. Due to their low production costs, unique surface chemistry, high chemical and thermal stability, as well as tailorable pore structures they are regarded as potential substitutes to liquid H2SO4. Catalysis, in particular, biomass and large molecule catalysis, is one of the important areas in which acidic carbons have demonstrated exceptional activity and selectivity, outperforming traditional solid acid catalysts (cation-exchange resins, sulfated oxides, and acidic zeolites). In this review we address developments in the different types SO3H- and PhSO3H-functionalized acidic carbon materials, their structure, active sites, and surface properties, applications in catalysis, as well as activation and deactivation characteristics covering important literature since 2004. In particular, we aim to provide a systematic discussion on the specific merits and demerits of such materials obtained from different carbon precursors and functionalization methods which directly influence the structure–stability–acidic properties and catalytic performance.

  • 35.
    Koroidov, Sergey
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Anderlund, Magnus F
    Styring, Stenbjörn
    Thapper, Anders
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    First turnover analysis of water-oxidation catalyzed by Co-oxide nanoparticles2015In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 8, no 8, p. 2492-2503Article in journal (Refereed)
    Abstract [en]

    Co-oxides are promising water oxidation catalysts for artificial photosynthesis devices. Presently, several different proposals exist for how they catalyze O-2 formation from water. Knowledge about this process at molecular detail will be required for their further improvement. Here we present time-resolved O-18-labelling isotope-ratio membrane-inlet mass spectrometry (MIMS) experiments to study the mechanism of water oxidation in Co/methylenediphosphonate (Co/M2P) oxide nanoparticles using [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine) as chemical oxidant. We show that O-16-Co/M2P-oxide nanoparticles produce O-16(2) during their first turnover after simultaneous addition of (H2O)-O-18 and [Ru(bpy)(3)](3+), while sequential addition with a delay of 3 s yields oxygen reflecting bulk water O-18-enrichment. This result is interpreted to show that the O-O bond formation in Co/M2P-oxide nanoparticles occurs via intramolecular oxygen coupling between two terminal Co-OHn ligands that are readily exchangeable with bulk water in the resting state of the catalyst. Importantly, our data allow the determination of the number of catalytic sites within this amorphous nanoparticular material, to calculate the TOF per catalytic site and to derive the number of holes needed for the production of the first O-2 molecule per catalytic site. We propose that the mechanism of O-O bond formation during bulk catalysis in amorphous Co-oxides may differ from that taking place at the surface of crystalline materials.

  • 36.
    Lundin, Lisa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stellan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Distribution of mono- to octa-chlorinated PCDD/F in fly ashes from a municipal solid waste incinerator2004In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, no 4, p. 1245-1250Article in journal (Refereed)
    Abstract [en]

    We have estimated the concentration and distribution of the mono to octa-chlorinated congeners of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in fly ashes at various sampling points in a large-scale municipal solid waste incinerator at Umeå, Sweden, as they cooled from 700 to 170 °C. Differences between the ashes were observed, the PCDD homologue profile was found to vary with temperature. The total amount of PCDD and PCDF increased as the temperature decreased in the postcombustion zone. The increase was due to both adsorption to the fly ash and formation of PCDD and PCDF. Mono- to trichlorinated PCDD predominated at high temperatures, whereas hepta- and octachlorinated PCDD predominated at temperatures below 400 °C. PCDF predominated over PCDD in the whole temperature range. However, the changes in homologue profile for PCDF were minor. The isomer distribution within the homologue groups was not changed as the temperature decreased in the postcombustion zone.

  • 37. Ma, Charlie
    Aspects of Ash Transformations in Pressurised Entrained-Flow Gasification of Woody Biomass: Pilot-scale studies2017Other (Other academic)
    Abstract [en]

    Pressurised entrained-flow gasification (PEFG) of woody biomass has the potential to produce high purity syngas for the production of vital chemicals, e.g., biofuels. However, ash-related issues such as reactor blockages and refractory corrosion need to be addressed before this potential can be realised from a technical perspective. These undesirable consequences can be brought about by slag formation involving inorganic ash-forming elements and the chemical transformations that they undergo during fuel conversion. The objective of this study was to elucidate the ash transformations of the major ash-forming elements and the slag formation process. A pilot-scale PEFG reactor was used as the basis of the study, gasifying different woody biomass-based fuels including wood, bark, and a bark/peat mixture. Different ash fractions were collected and chemically analysed. Reactor slags had elemental distributions differing from that of the fuel ash, indicating the occurrence of fractionation of ash material during fuel conversion. Fly ash particles from a bark campaign were also heterogeneous with particles exhibiting differing compositions and physical properties; e.g., molten and crystalline formations. Si was consistently enriched in the reactor slags compared to other major ash-forming elements, while analyses of other ash fractions indicated that K was likely volatilised to a significant extent. In terms of slag behaviour, near-wall temperatures of approximately 1050-1200 °C inside the reactor were insufficient to form flowing ash slag for continuous extraction of ash material during firing the woody biomass fuels alone. However, fuel blending of a bark fuel with a silica-rich peat changed the chemical composition of the reactor slags and bulk slag flow behaviour was evident. Thermochemical equilibrium calculations supported the importance of Si in melt formation and in lowering solidus and liquidus temperatures of Ca-rich slag compositions that are typical from clean wood and bark. Viscosity estimations also showed the impact that solids have upon slag flow behaviour and corresponded qualitatively to the experimental observations. Corrosion of reactor refractory was observed. The mullite-based refractory of the reactor formed a slag with the fuel ash slag, which caused the former to flux away. Reactor blockages were also resultant because of the high viscosity of this slag near the outlet.  A preliminary study into the corrosion of different refractories was also carried out, based on firing a bark/peat mixture.  Alumina-rich refractories consisting of corundum, hibonite, mullite, and andalusite tended to form anorthite and exhibited varying degrees of degradation. Infiltration of slag was evident for all the samples and was a severe mode of degradation for some refractories. For fused-cast periclase and spinel-based refractories, slag infiltration was limited to voids and no extensive signs of refractory dissolution were found. This is also supported by a thermochemical equilibrium calculations mimicking slag infiltration that incorporated viscosity estimations. The findings from this thesis contribute towards the development of woody biomass PEFG by highlighting issues concerning ash fractionation, slag behaviours and ash\slash refractory interaction that should be investigated further.

  • 38. Ma, Charlie
    Slag Formation During Pilot-Scale Pressurised Entrained-Flow Gasification of Woody Biomass2014Other (Other academic)
    Abstract [en]

    Pressurised entrained‐flow gasification (PEFG) of sustainable woody biomass offers the opportunity for envi-ronmentally benign production of syngas that is suitable for synthesis of fuels and other chemicals. During the PEFG process, ash-forming matter in the fuel undergoes transformations. Slag formation is an important form of ash transformation that occurs inside a PEFG reactor. In most industrial-scale PEFG of coal, the ash-forming matter becomes predominately molten and flows down the side of the reactor wall to be continuously tapped and removed. The slagging behaviour of woody biomass fuels during PEFG is expected to be different to that of coal, due to significant differences in the amount, composition and reactivity of the ash-forming matter. The objective of this thesis study was to initiate the elucidation of slag formation during PEFG of woody biomass. This was carried out by obtaining and characterising ash deposits and slags from pilot-scale experimental cam-paigns. An oxygen-fired pilot-scale reactor (ETC Piteå, Sweden) was used for the study. A low reactor temperature (< 1200 °C) study was carried out with three different fuels fired in separate experimental campaigns: stem wood, bark and pulp mill debarking residue (PMDR). Deposits were taken from each of the campaigns from the reactor for chemical characterisation. The stem wood fuel resulted in very little deposit that exhibited only minor amounts of melt, or slag, formation with enrichment of Si. The bark and PMDR fuels resulted in larger amounts of deposits with greater amounts of melt formation that were also enriched in Si. It was found that silica-based fuel contaminants, e.g., quartz sand and feldspars, may have an important role in melt formation. Following on, high reactor temperature (> 1350 °C) experimental campaigns involving stem wood produced flowing slags that eventuated in blockages of the reactor outlet. These slags were also retrieved from the reactor and characterised. It was found that they likely comprised of products resulting from detrimental interactions between the fuel ash and the mullite-based refractory used for the reactor wall lining. Viscosity models and thermochemical equilibrium calculations (TECs) were utilised to offer an explanation for the behaviour of the slags. Additional TECs were carried out to investigate the propensity for melt formation between the main ash-forming elements of woody biomass, Ca, K and Si, under global reactor conditions with relevance to PEFG. The results showed that, in general, the conditions for melt formation are broadened with increasing pressure, increasing amounts of Si and increased concentrations of gaseous K species. Dissolution of Al₂O₃ from mullite (Al₆Si₂O₁₃) refractory due to ash deposits and the gasification atmosphere was also predicted by the calculations. A scheme of slag formation during PEFG of woody biomass in a reactor with mullite-based refractory lining was proposed in light of the experimental observations. Some practical suggestions to avoid ash-related problems during PEFG of woody biomass are also discussed. This work forms part of a broader study to elucidate the ash transformations that occur during PEFG of woody biomass, which is necessary in order to develop the process into commercial availability.

  • 39. Ma, Charlie
    et al.
    Weiland, Fredrik
    Hedman, Henry
    Boström, Dan
    Backman, Rainer
    Öhman, Marcus
    Characterization of Reactor Ash Deposits from Pilot-Scale Pressurized Entrained-Flow Gasification of Woody Biomass2013In: Energy & Fuels, Vol. 27, no 11, p. 6801-6814Article in journal (Refereed)
    Abstract [en]

    Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

  • 40.
    Miranda La Hera, Pedro
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Rehman, Bilal Ur
    Sandberg, Anders
    Modeling an industrial flotation process: A case study at the mining company Boliden AB2012In: 2012 WORLD AUTOMATION CONGRESS (WAC), IEEE , 2012, p. 1-5Conference paper (Refereed)
    Abstract [en]

    We present results of modeling dynamics of a copper flotation pl'ocess, for which conventional system identification methods are applied. To this end, experimental studies are performed at an open pit mine belonging to the Swedish mining company Boliden AB. The main idea is to identify linear plants, that approximate dynamics of the process around neighborhoods of cost efficient working conditions. These models are intended to be applied for the design of model based control strategies, and to assess better studies of performance optimization. The results of simulation tests show a satisfactory agreement in between the identified models performance and the measured variables.

  • 41. Mohammadi, Marzieh
    et al.
    Shafiei, Marzieh
    Karimi, Keikhosro
    Abdolmaleki, Amir
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Larsson, Christer
    Improvement of ethanol production from birch and spruce pretreated with 1-H-3-methylmorpholinium chloride2019In: Electronic Journal of Biotechnology, ISSN 0717-3458, E-ISSN 0717-3458, Vol. 41, p. 95-99Article in journal (Refereed)
    Abstract [en]

    Background: Pretreatment is the critically important step for the production of ethanol from lignocelluloses. In this study, hardwood birch (Betula pendula) and softwood spruce (Norway spruce) woods were pretreated with a newly synthesized morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]), followed by enzymatic hydrolysis and fermentation to ethanol.

    Results: [HMMorph][Cl] was synthesized using inexpensive raw materials, i.e., hydrochloric acid and N-methyl morpholine, following a simple process. The influence of pretreatment time (2, 3, 5, and 8 h) and temperature (120 and 140°C) in terms of hydrolysis efficiency was investigated. Glucose yields from enzymatic hydrolysis were improved from 13.7% to 45.7% and 12.9% to 51.8% after pretreatment of birch and spruce woods, respectively, under optimum pretreatment conditions (i.e., at 140°C for 3 h) as compared to those from pristine woods. Moreover, the yields of ethanol production from birch and spruce were increased to 34.8% and 44.2%, respectively, while the yields were negligible for untreated woods.

    Conclusions: This study demonstrated the ability of [HMMorph][Cl] as an inexpensive agent to pretreat both softwood and hardwood.

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  • 42. Moilanen, Antero
    et al.
    Lehtinen, Jere
    Kurkela, Minna
    Muhola, Mirja
    Tuomi, Sanna
    Carlsson, Per
    Öhman, Marcus
    Güell, Berta Matas
    Sandquist, Judit
    Lundgren, Joakim
    Andersson, Jim
    Umeki, Kentaro
    Ma, Charlie
    Kurkela, Esa
    Wiinikka, Henrik
    Wang, Liang
    Backman, Rainer
    Biomass gasification fundamentals to support the development of BTL in forest industry2015Report (Other academic)
  • 43. Moradian, Farzad
    et al.
    Tchoffor, Placid A.
    Davidsson, Kent O.
    Pettersson, Anita
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized-bed gasification of forest residues2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 154, p. 82-90Article in journal (Refereed)
    Abstract [en]

    Dual fluidized-bed (DFB) gasification is one of the recently developed technologies for production of heat, power, transportation fuels and synthetic chemicals through steam gasification of biomass. Bed agglomeration is a serious ash-related problem that should be taken into account when biomass-based fuels are selected for fluidized bed gasification and combustion. This study developed a thermodynamic equilibrium model to assess the risk of bed agglomeration in gasification and combustion reactors of a DFB gasifier using biomass (forest residues) as feedstock. The modelling approach combined thermodynamic equilibrium calculations with chemical fractionation technique to predict the composition and melting behaviour of the fuel-derived ash as well as bed particles coating layer in the gasification and combustion reactors. FactSage was employed for the thermodynamic equilibrium calculations. The modelling results were then compared with experimental data obtained from a full-scale DFB gasifier to estimate the reliability and validity of the predictive model. In general, a good agreement was found between the modelling results and experimental observations. For the forest residues as feedstock and olivine as bed material, the modelling results indicate a low risk of bed agglomeration in the DFB gasifier, as long as the dominant temperature in the combustion zone is below 1020 degrees C. In contrast, quartz as bed material in the DFB gasifier was shown to significantly increase the risk of bed agglomeration through coating-induced agglomeration mechanism. 

  • 44.
    Mukesh, Chandrakant
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nikjoo, Dariush
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Production of C-14 Levulinate Ester from Glucose Fermentation Liquors Catalyzed by Acidic Ionic Liquids in a Solvent-Free Self-Biphasic System2020In: ACS Omega, ISSN 2470-1343, Vol. 5, no 10, p. 4828-4835Article in journal (Refereed)
    Abstract [en]

    Herein, we present the C-14 levulinate ester of 2,3-butanediol as the product of sugar fermentation liquors. The designed Brønsted acidic ionic liquid (BAIL) catalysts enable self-induced phase separation with ester products, and the role of anions has been investigated. Esterification reactions were carried out by 2,3-butanediol (2,3-BDO) and levulinic acid in solvent-free media and low temperatures (60–105 °C). For comparison, sulfuric acid, amberlite IR-120, and sulfonic acid-functionalized pyridinium ionic liquids with different anions were utilized as a catalyst upon esterification reaction. The diester product, namely, butane-2,3-diyl bis(4-oxopentanoate), was formed with a good yield (85%) and selectivity (85%) after complete conversion of 2,3-BDO in 24 h at 80 °C. The low yield (8%) of the monoester was observed. The monoester and diester were separated by a liquid–liquid extraction method. The ester products were characterized by various instrumental techniques such as 1H and 13C NMR, GC–FID, LC–MS, and FT-IR spectroscopy. The Hammett acidity functions of BAILs were determined from UV–vis spectroscopy. The catalyst was successfully recycled and reused in the processes. The spent BAILs were reused in six consecutive cycles with only a ∼7% diminished diester yield and selectivity. The produced levulinate ester will be useful as biofuel additives, solvents, plasticizers, and other applications.

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  • 45.
    Nguyen, Anh Mai
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nguyen, Thanh Duc
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sizeable Macroporous Monolithic Polyamide Entities Prepared in Closed Molds by Thermally Mediated Dissolution and Phase Segregation2008In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, no 19, p. 6244-6247Article in journal (Refereed)
    Abstract [en]

    A simple method is presented for the preparation of macroporous monoliths from an aliphatic polyamide in closed molds, based on swelling/dissolution in benzyl alcohol at elevated temperature, followed by precipitation into a continuous monolithic structure by cooling the solution below the upper critical solution temperature. Subsequent removal of the solvent led to the formation of rigid macroporous nylon monoliths with a continuous and evenly spaced macropore system. The intended use is as supports for flow-through systems, where efficient mass transport at low flow resistance is the key optimization criterion.

  • 46. Norheim, Arnstein
    et al.
    Waernhus, Ivar
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hustad, Johan E.
    Vik, Arild
    Experimental Studies on the Influence of H2S on Solid Oxide Fuel Cell Performance at 800 °C2007In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 21, no 2, p. 1098-1101Article in journal (Refereed)
    Abstract [en]

    Short-term tests showing the influence sulfur has on solid oxide fuel cell (SOFC) performance have been performed. The experiments were performed using two single-cell SOFC setups operated at 800 degrees C. In setup I, sulfur (H2S) was mixed into the fuel gas in concentrations ranging from 20 to 100 ppm. It was found that the performance decreased with increasing sulfur concentration up to 80 ppm. The performance loss at 80 and 100 ppm sulfur was equal. At a current density of 200 mA cm(-2), the operating voltage was reduced from 0.810 V at 0 ppm H2S to 0.790 V at 100 ppm H2S, corresponding to an increase in the area-specific cell resistivity (ASR) of 0.10 Omega cm(2). In setup II, sulfur levels of 80, 120, and 240 ppm were introduced. In all these three cases the ASR increased by around 0.13 Omega cm(2). Removing the sulfur impurity when the 240 ppm H2S exposure test was finished the cell performance fully recovered, indicating no irreversible changes in the cell structure.

  • 47. Olofsson, Ingemar
    et al.
    Strandberg, Martin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Oxygen enhanced torrefaction - An initial feasibility studyManuscript (preprint) (Other academic)
    Abstract [en]

    Upcoming world market prices on thermally treated and densified biomass to be feasible for coal replacement put a high demand on the process suppliers to deliver cost efficient and high energy yield conversion systems with a capacity to produce a high quality product. One of the more complex and vital parts in a torrefaction facility is the indirect or direct heat transfer system applied. This is a critical task that also may limit the scale-up potential and thus influence the economy of scale of a complete torrefaction system.

    In the present study, it was demonstrated that the torrefaction reactions in a rotary drum pilot reactor (20 kgDS/h) potentially may be operated autothermally by a low level injection of air directly into the reactor for controlled in-situ partial combustion of the released torrefaction gases. Both concurrent and countercurrent gas flow patterns were evaluated for different process temperatures. At higher temperatures (338°C) in countercurrent gas flow mode, steady-state torrefaction was reached without external heat supply. The resulting torrefied biomass had higher heating value, higher carbon content and lower milling energy consumption, compared to non-oxidative torrefied biomass with same mass yield. Condensation of torrefaction gas compounds is a suggested reason.No significant decrease in the combustibility of the torrefaction gas was experienced.  The demonstrated Oxygen Enhanced Torrefaction (OET) mode thus has the potential to improve the torrefaction systems in terms of scale-up performance with reduced investment and operational costs but further validation work is needed to confirm the present findings and also to identify working conditions.

  • 48. Pezoa-Conte, Ricardo
    et al.
    Leyton, Allison
    Baccini, Andrea
    Ravanal, María Cristina
    Mäki-Arvela, Päivi
    Grénman, Henrik
    Xu, Chunlin
    Willför, Stefan
    Lienqueo, María Elena
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Abo Akad Univ, Ind Chem & React Engn, Johan Gadolin Proc Chem Ctr, Biskopsgatan 8, FI-20500 Turku, Finland.
    Aqueous Extraction of the Sulfated Polysaccharide Ulvan from the Green Alga Ulva rigida: Kinetics and Modeling2017In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 10, no 3, p. 915-928Article in journal (Refereed)
    Abstract [en]

    The incentives for utilizing a versatile range of renewable feedstocks in novel ways are continuously increasing. Sulfated polysaccharides from green algae, such as ulvan, are interesting due to the rare sugar constituents which can be utilized for new materials and chemicals in industry. However, before valorization fractionation needs to be performed in a controlled way. In the current work, the kinetics of the aqueous extraction of ulvan was studied in the temperature range 60–130 °C. The highest yield of 97.6 wt.% was attained after 2 h of extraction at 130 °C, and the extraction efficiency was observed to be heavily temperature dependent. Interestingly, two regimes of extraction kinetics were observed, presumably due to the different ulvan fractions contained within the cell wall of green algae. The experimental data was modeled with first-order kinetics, and an apparent activation energy of 53.8 kJ mol−1 was obtained for the process. The algal residue was processed using simultaneous saccharification and fermentation, and 0.48 g ethanol g−1 of sugars was obtained.

  • 49.
    Qu, Zhechao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fagerström, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Steinvall, Erik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Florian, Schmidt
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Real-time In-Situ Detection of Potassium Release during Combustion of Pelletized Biomass using Tunable Diode Laser Absorption Spectroscopy2014In: Impacts of Fuel Quality on Power Production October 26 –31, 2014, Snowbird, Utah, USA, 2014, p. 1-14Conference paper (Other academic)
    Abstract [en]

    Tunable diode laser absorption spectroscopy (TDLAS) was used for quantitative in-situ detection of gaseous elemental potassium (K) at distances 2-11 mm above biomass pellets combusted in a macro-thermogravimetric analyzer (macro-TGA). Single pellets of energy wood (EW) and wheat straw (WS) were converted in air at a furnace temperature of 850 °C and a carrier flow rate of 15 liters per minute. A second TDLAS system measured water vapor concentration and temperature above the pellets. In addition, semi-time-resolved K release data was obtained from conventional ICP-MS/AES analysis of fuel/ash residues collected at several occasions during devolatilization and char combustion. It was found that the fuels differ with respect to relative K-release and temporal release histories. Significant concentrations of K(g) were detected with TDLAS above the pellets during devolatilization, but no K(g) was observed during char combustion, independent of the fuel type. The amount of K(g)tot measured above the pellets during devolatilization was larger for EW than for WS, even though the total K content of WS was a factor of 60 higher. By combining TDLAS and ICP data, and supported by equilibrium calculations, these results indicate that, during devocalization, K is mainly released as KCl from wheat straw, whereas both KCl and KOH are released from energy wood.

  • 50.
    Qu, Zhechao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Holmgren, Per
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Energy Engineering, Department of Engineering Sciences & Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden.
    Wagner, David R.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Distribution of temperature, H2O and atomic potassium during entrained flow biomass combustion: coupling in situ TDLAS with modeling approaches and ash chemistry2018In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 188, p. 488-497Article in journal (Refereed)
    Abstract [en]

    Tunable diode laser absorption spectroscopy (TDLAS) is employed for simultaneous detection of gas temperature, water vapor (H2O) and gas-phase atomic potassium, K(g), in an atmospheric, research-scale entrained flow reactor (EFR). In situ measurements are conducted at four different locations in the EFR core to study the progress of thermochemical conversion of softwood and Miscanthus powders with focus on the primary potassium reactions. In an initial validation step during propane flame operation, the measured axial EFR profiles of H2O density-weighted, path-averaged temperature, path-averaged H2O concentration and H2O column density are found in good agreement with 2D CFD simulations and standard flue gas analysis. During biomass conversion, temperature and H2O are significantly higher than for the propane flame, up to 1500 K and 9%, respectively, and K(g) concentrations between 0.2 and 270 ppbv are observed. Despite the large difference in initial potassium content between the fuels, the K(g) concentrations obtained at each EFR location are comparable, which highlights the importance of considering all major ash-forming elements in the fuel matrix. For both fuels, temperature and K(g) decrease with residence time, and in the lower part of the EFR, K(g) is in excellent agreement with thermodynamic equilibrium calculations evaluated at the TDLAS-measured temperatures and H2O concentrations. However, in the upper part of the EFR, where the measured H2O suggested a global equivalence ratio smaller than unity, K(g) is far below the predicted equilibrium values. This indicates that, in contrast to the organic compounds, potassium species rapidly undergo primary ash transformation reactions even if the fuel particles reside in an oxygen-deficient environment.

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