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  • 1.
    Biswas, Amit
    et al.
    Luleå Tekniska Universitet.
    Rudolfsson, Magnus
    Sveriges Lantbruksuniversitet.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Umeki, Kentaro
    Luleå Tekniska Universitet.
    Effect of pelletizing conditions on combustion behaviour of single wood pellet2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 119, no 15, p. 79-84Article in journal (Refereed)
    Abstract [en]

    This paper presents how pelletizing die temperature and moisture content affect combustion behaviour of single wood pellet. Pine wood particles with two different moisture contents (i.e. 1 wt.% and 12 wt.%) were pelletized in a laboratory-scale single pelletizer (single die pellets) at die temperature of 20, 100, 150 and 200 °C. The pellets were combusted in a laboratory scale furnace at 800 °C. Time required for single pellet combustion generally increased with both increase of pelletizing temperature and moisture content of biomass. In addition, combustion behaviour of single die pellets was significantly different than those produced in a pilot scale pelletizing plant (semi-industrial scale pellet). That difference was due to variation in physical properties of pellets (e.g. density, and morphology).

  • 2.
    Boman, Christoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Broström, Markus
    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.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal (Other academic)
  • 3.
    Borén, Eleonora
    et al.
    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.
    Kajsa, Werner
    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.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Defining the temperature regime of gaseous degradation products of Norway spruce2013In: 21nd European Biomass Conference and Exhibition, Copenhagen, June, 2013, ETA Florens Renewable Energies, 2013, 2013Conference paper (Other academic)
  • 4.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Industrial Doctoral School for Research and Innovation, Umeå University, Umeå, Sweden.
    Larsson, Sylvia H.
    Biomass Technology Centre, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Andreas, Averheim
    Mikael, Thyrel
    Biomass Technology Centre, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Reducing VOC off-gassing during the production of pelletized steam-exploded bark: impact of storage time and controlled ventilation2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 4, p. 5181-5186Article in journal (Refereed)
    Abstract [en]

    Volatile organic compound (VOC) off-gassing behavior of thermally treated biomass intended for bioenergy production has recently been shown to be vastly different from that of untreated biomass. Simple measures to reduce emissions, such as controlled ventilation and prolonged storage time, have been suggested but not yet studied in detail. In the present study, we monitored how VOC off-gassing was reduced over time (24–144 h) in enclosed storage with and without ventilation. Steam-exploded bark was collected directly from a pilot-scale steam explosion plant as well as before and after subsequent pelletizing. Active Tenax-TA absorbent sampling of VOCs was performed from the headspaces of a bench-scale sample storage setup. The impact of storage time and ventilation on VOC levels was evaluated through multivariate statistical analysis. The results showed that relative VOC concentrations in the headspace were reduced by increased storage time, with heavier VOCs reduced at a higher rate. VOC composition was neither reduced nor shifted by controlled intermittent ventilation during storage; instead, VOC levels equilibrated at the same levels as those stored without ventilation, and this was independent of the process step, storage time, or number of ventilations.

  • 5.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Averheim, Andreas
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Reducing VOCs off-gassing during production of pelletized steam exploded bark: impact of storage time and controlled ventilationManuscript (preprint) (Other academic)
    Abstract [en]

    VOC off-gassing behavior of thermally treated biomass intended for bioenergy production has recently been shown to be vastly different to that of untreated biomass. Simple measures to reduce emissions, such as controlled ventilation and prolonged storage time, has been suggested but not previously studied in detail. In the present study, we monitored how VOC off-gassing was reduced over time (24–144h) in closed storage with and without ventilation. Steam exploded bark was collected directly from a pilot scale steam explosion plant, and before and after subsequent pelletizing. Storage and active sampling of VOCs in the headspace was done in a bench-scale set-up using Tenax-TA absorbent. The impact of storage time and ventilation to reduce VOCs was evaluated through multivariate statistical analysis. The results showed that VOC concentrations in the headspace were reduced by increased storage time, and that heavier VOCs reduced faster. No impact on either reducing or shifting VOC composition could be achieved by controlled ventilation during storage; instead, VOCs emitted to the same concentrations anew, independent of process step, storage time, or number of ventilations.

  • 6.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Thyrel, Mikael
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Averheim, Andreas
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    VOC off-gassing from pelletized steam exploded softwood bark: emissions at different industrial process stepsIn: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188Article in journal (Refereed)
    Abstract [en]

    Formation of hazardous gases during transport and storage of biomass for large-scale bioenergy production is an important safety concern. While off-gassing has been addressed in numerous studies for raw woody biomass, very few describe it in the context of biomass for bioenergy production pre-treated by thermal technologies such as steam explosion. Volatile Organic Components (VOCs) are expected to be altered by the treatment, but until now there is no research published on VOC profiles of steam exploded materials in industrial scale. In the present study, VOCs emitted from the products were evaluated by sampling from different production steps from steam explosion of softwood bark, and following the production chain including also pelletization. Off-gasses were actively sampled using Tenax TA absorbent and analyzed by GC-MS. The VOC formation dependency of operation and storage conditions at different process steps was evaluated by multivariate statistical analysis. We showed that the different process steps along the production line was the main influencing factor for VOC off-gassing amounts, with highest VOC levels directly after the steam explosion process. Treatment severity mainly altered the relative composition of VOC profiles with more terpenes emitted from milder treatment, whereas more severe treatment shifted VOCs composition to contain more furans, e.g. furfural. In summary, treatment by steam explosion leads to potentially problematic VOC off-gassing profiles from the material, and levels vary considerable along the production line. The findings are important from a fuel handling and working environment perspective.

  • 7.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University Industrial Doctoral School for Research and Innovation, Sweden.
    Larsson, Sylvia H.
    Thyrel, Mikael
    Averheim, Andreas
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    VOC off-gassing from pelletized steam exploded softwood bark: emissions at different industrial process steps2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 171, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Formation of hazardous gases during transport and storage of biomass for large-scale bioenergy production is an important safety concern. While off-gassing has been addressed in numerous studies for raw woody biomass, very few describe it in the context of biomass for bioenergy production pre-treated by thermal technologies such as steam explosion. Volatile Organic Components (VOCs) are expected to be altered by the treatment, but until now there is no research published on VOC profiles of steam exploded materials in industrial scale. In the present study, VOCs emitted from the products were evaluated by sampling from different production steps from steam explosion of softwood bark, and following the production chain including also pelletization. Off-gasses were actively sampled using Tenax TA absorbent and analyzed by GC–MS. The VOC formation dependency of operation and storage conditions at different process steps was evaluated by multivariate statistical analysis. We showed that the different process steps along the production line was the main influencing factor for VOC off-gassing amounts, with highest VOC levels directly after the steam explosion process. Treatment severity mainly altered the relative composition of VOC profiles with more terpenes emitted from milder treatment, whereas more severe treatment shifted VOCs composition to contain more furans, e.g. furfural. In summary, treatment by steam explosion leads to potentially problematic VOC off-gassing profiles from the material, and levels vary considerable along the production line. The findings are important from a fuel handling and working environment perspective.

  • 8.
    Borén, Eleonora
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University Industrial Doctoral School for Research and Innovation.
    Yazdanpanah, Fahimeh
    Lindahl, Roger
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schilling, Christoph
    Chandra, Richard P.
    Ghiasi, Bahman
    Tang, Yong
    Sokhansanj, Shahabaddine
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Off-gassing of VOCs and permanent gases during storage of torrefied and steam exploded wood2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 10954-10965Article in journal (Refereed)
    Abstract [en]

    Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO2, CH4, and O2 depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N2), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O2 depletion.

  • 9.
    Boström, Dan
    et al.
    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.
    Lindström, Erika
    Boman, Christoffer
    Backman, Rainer
    Öhman, Marcus
    Grimm, Alejandro
    Ash transformation chemisty during energy conversion of agricultural biomass2009In: International Conference on Solid Biofuels, ICSB2009, Beijing, China, 2009Conference paper (Other academic)
  • 10.
    Boström, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Engineering.
    Ash transformation chemistry during energy conversion of biomass2010In: Impacts of Fuel Quality on Power Production & Environment: 29/08/2010 - 03/09/2010, Impacts of Fuel Quality , 2010Conference paper (Refereed)
    Abstract [en]

    There is relatively extensive knowledge available concerning ash transformation reactions during energy conversion of woody biomass. Traditionally, these assortments have constituted the main resources for heating in Sweden. In recent decades the utilization of these energy carriers has increased, from a low technology residential small scale level to industrial scale (e.g. CHP plants). Along this evolution ash-chemical related phenomena for woody biomass has been observed and studied. So, presently the understanding for these are, if not complete, fairly good. Briefly, from a chemical point of view the ash from woody biomass could be characterized as a silicate dominated systems with varying content of basic oxides and with relatively high degree of volatilization of alkali sulfates and chlorides. Thus, the main ash transformation mechanisms in these systems have been outlined. Here, an attempt to give a general description of the ash transformation reactions of biomass fuels is presented, with the intention to provide guidance in the understanding of ash matter behavior in the utilization of any biomass fuel, primarily from knowledge of the concentrations of ash forming elements but also by considering the physical condition in the specific combustion appliance and the physical characteristic of the biomass fuel. Furthermore, since the demand for CO2-neutral energy resources has increased the last years and will continue to do so in the foreseeable future, other biomasses as for instance agricultural crops has become highly interesting. Globally, the availability of these shows large variation. In Sweden, for instance, which is a relatively spare populated country with large forests, these bio-masses will play a secondary role, although not insignificant. In other parts of the world, more densely populated and with a large agricultural sector, such bio-masses may constitute the main energy bio-mass resource in the future. However, the content of ash forming matter in agricultural bio-mass is rather different in comparison to woody biomass. Firstly, the content is much higher; from being about 0.3 – 0.5% (wt) in stem wood, it can amount to between 2 and 10 %(wt) in agricultural biomass. In addition, the composition of the ash forming matter is different. Shortly, the main difference is due to a much higher content of phosphorus (occasionally also silicon) which has major consequences on the ash-transformation reactions. In many crops, the concentration of phosphorus and silicon is equivalent, which (depending on the concentration levels of basic oxides) may result in a phosphate dominated ash. The properties of this ash are in several aspects different from the silicate dominated woody biomass ash and will consequently behave differently in various types of energy conversion systems. The knowledge about phosphate dominated ash systems has so far been scarce. We have been working with these systems, both with basic and applied research, for about a decade know. Some general experiences and conclusions as well as some specific examples of our research will be presented.

  • 11.
    Boström, Dan
    et al.
    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.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    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.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash transformation chemistry during combustion of biomass, theory and technical applications2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal (Other academic)
  • 12.
    Boström, Dan
    et al.
    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.
    Grimm, Alejandro
    Luleå Univ Technol, Div Energy Sci, SE-97187 Luleå, Sweden.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Öhman, Marcus
    Luleå Univ Technol, Div Energy Sci, SE-97187 Luleå, Sweden.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash Transformation Chemistry during Combustion of Biomass2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 1, p. 85-93Article in journal (Refereed)
    Abstract [en]

    There is relatively extensive knowledge available concerning ash transformation reactions during combustion of woody biomass. In recent decades, the use of these energy carriers has increased, from a low-technology residential small-scale level to an industrial scale. Along this evolution, ash chemical-related phenomena for woody biomass have been observed and studied. Therefore, presently the understanding for these are, if not complete, fairly good. However, because the demand for CO2-neutral energy resources has increased recently and will continue to increase in the foreseeable future, other biomasses, such as, for instance, agricultural crops, have become highly interesting. The ash-forming matter in agricultural biomass is rather different in comparison to woody biomass, with a higher content of phosphorus as a distinctive feature. The knowledge about the ash transformation behavior in these systems is far from complete. Here, an attempt to give a schematic but general description of the ash transformation reactions of biomass fuels is presented in terms of a conceptual model, with the intention to provide guidance in the understanding of ash matter behavior in the use of any biomass fuel, primarily from the knowledge of the concentrations of ash-forming elements. The model was organized in primary and secondary reactions. Restrictions on the theoretical model in terms of reactivity limitations and physical conditions of the conversion process were discussed and exemplified, and some principal differences between biomass ashes dominated by Si and P, separately, were outlined and discussed.

  • 13.
    Branca, Carmen
    et al.
    Istituto di Ricerche sulla Combustione, C.N.R., P.le V. Tecchio, 80125 Napoli, Italy.
    Di Blasi, Colomba
    Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli “Federico II”, P.le V. Tecchio, 80125 Napoli, Italy.
    Galgano, Antonio
    Istituto di Ricerche sulla Combustione, C.N.R., P.le V. Tecchio, 80125 Napoli, Italy.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Effects of the Torrefaction Conditions on the Fixed-Bed Pyrolysis of Norway Spruce2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 9, p. 5882-5891Article in journal (Refereed)
    Abstract [en]

    Fixed-bed pyrolysis of Norway spruce wood previously subjected to torrefaction at temperatures between 533 and 583 K and retention times between 8 and 25 min was studied. Although the thermal pretreatment always results in an increased production of char at the expense of volatile products, appropriate torrefaction conditions give rise to maximum percentages of anhydrosugars, guaiacols possessing a carbonyl group, and phenols in the liquid fraction. Other carbohydrates (e.g., acetic acid, formic acid, hydroxyacetaldehyde, hydroxypropanone, furfural, and furfuryl alcohol) and the large majority of guaiacols show continuously decreasing values. The percentages of carbon monoxide and carbon dioxide in the gas product remain approximately the same, but that of methane slightly increases. The pyrolysis temperatures of torrefied wood are lower than those of the raw material, mainly because of the partial or complete absence of the exothermic contribution associated with extractives and hemicellulose degradation.

  • 14.
    Brostrom, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Pommer, Linda
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Branca, C.
    Di Blasi, C.
    Influence of torrefaction on the devolatilization and oxidation kinetics of wood2012In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 96, p. 100-109Article in journal (Refereed)
    Abstract [en]

    Devolatilization and oxidation kinetics of torrefied wood have been studied by evaluating thermogravimetric curves measured in nitrogen and air at various heating rates. Samples consist of Norway spruce wood chips torrefied at several process temperatures and residence times. Data about untreated wood have also been obtained for comparison. Measured curves are well predicted by means of a five-reaction mechanism, consisting of three devolatilization reactions for the pseudo-components hemicellulose. cellulose and lignin and, in air, of two additional reactions for char devolatilization and combustion. The torrefaction pre-treatment only requires model modifications in the amounts of volatiles generated from the decomposition of pseudo-components, indicating that only their relative percentages and not their reactivities are modified. On the other hand, a slightly different thermal stability is found for the char generated from torrefied wood, which results in higher activation energy and lower reaction order for the oxidation step. Hence torrefaction conditions can affect the subsequent conversion characteristics of the char product. (C) 2012 Elsevier B.V. All rights reserved.

  • 15.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Aspects of alkali chloride chemistry on deposit formation and high temperature corrosion in biomass and waste fired boilers2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Combustion of biomass and waste has several environmental, economical and political advantages over the use of fossil fuels for the generation of heat and electricity. However, these fuels often have a significantly different composition and the combustion is therefore associated with additional operational problems. A high content of chlorine and alkali metals (potassium and sodium) often causes problems with deposit formation and high temperature corrosion. Some different aspects of these issues are addressed in this thesis.

    The overall objective of this thesis was to study and highlight different means by which operational problems related to alkali chlorides can be overcome, reduced or prevented.

    The most important results of this thesis are: (1) A full description of the in-situ alkali chloride monitor, its operational principles, the calibration procedure, and an example of a full-scale application was made public in a scientific publication. (2) Efficient sulfation of gaseous alkali chlorides in a full-scale boiler was achieved by injecting ammonium sulfate in a water solution into the hot flue gas. (3) Reduced deposit growth and corrosion rates were achieved by lowering the alkali chloride concentration in the flue gas by sulfation. (4) Evidence of decreased deposit growth and chlorine content in deposits during peat co-combustion. (5) Results are presented from high temperature corrosion tests with different superheater steels in two different combustion environments. (6) Controlled KCl and NaCl condensation under simulated combustion conditions resulted in deposits which consisted of mostly pure phases, in contrast to the solid solution that would be expected under the prevailing conditions at chemical equilibrium.

  • 16.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Effects of alkali chlorides in biomass and waste-fired boilers2009Licentiate thesis, comprehensive summary (Other academic)
  • 17.
    Broström, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Andersson, Christer
    Axner, Ove
    Nordin, Anders
    IACM - In situ alkali chloride monitor2004In: 2nd World Conference for Energy, Industry and Climate Protection, Rome, Italy, 2004Conference paper (Other academic)
  • 18.
    Broström, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Enestam, Sonja
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mäkelä, Kari
    Condensation in the KCl–NaCl system2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, p. 142-148Article in journal (Refereed)
    Abstract [en]

    Condensation of gaseous KCl and NaCl is known to participate in deposit formation and high temperature corrosion processes in heat and power plants. Little is known about interaction between the two salts, which is of interest for the overall understanding of deposit and corrosion problems. Within this study, condensation at different material surface temperatures and salt mixtures was investigated.

    Salt vapors were prepared by temperature controlled evaporation. A cooled condensation probe with a temperature gradient was inserted in the hot gas. After exposure, the probe surface was visually inspected and analyzed with SEM/EDS and XRD for elemental and phase composition. TGA/DTA was used to provide complementary information on vaporization and sintering.

    The results indicated that a mixture of KCl and NaCl probably condenses as separate phases at concentrations and temperatures below the melting points of the salts. Condensation was possibly followed by a secondary sintering process. It was verified by TGA/DTA that a mixture of solid KCl and NaCl particles sinters and melts rapidly at temperatures above the melting temperature of a corresponding solution. It was also seen that sintering took place at lower temperatures with slow solid-gas interactions, possibly with the formation of solid solutions.

  • 19.
    Broström, Markus
    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.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ash fractionation and slag formation during entrained flow biomass gasification2018Conference paper (Other academic)
  • 20.
    Broström, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Kassman, Håkan
    Vattenfall Power Consultant AB, Box 1046, SE-611 29 Nyköping, Sweden.
    Helgesson, Anna
    Vattenfall Research and Development AB, SE-814 26 Älvkarleby, Sweden.
    Berg, Magnus
    Vattenfall Research and Development AB, SE-814 26 Älvkarleby, Sweden.
    Andersson, Christer
    Vattenfall Research and Development AB, SE-814 26 Älvkarleby, Sweden.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Sulfation of corrosive alkali chlorides by ammonium sulfate in a biomass fired CFB boiler2007In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 88, no 11-12, p. 1171-1177Article in journal (Refereed)
    Abstract [en]

    Biomass and waste derived fuels contain relatively high amounts of alkali and chlorine, but contain very little sulfur. Combustion of such fuels can result in increased deposit formation and superheater corrosion. These problems can be reduced by using a sulfur containing additive, such as ammonium sulfate, which reacts with the alkali chlorides and forms less corrosive sulfates. Ammonium sulfate injection together with a so-called in situ alkali chloride monitor (IACM) is patented and known as "ChlorOut". IACM measures the concentrations of alkali chlorides (mainly KCl in biomass combustion) at superheater temperatures. Tests with and without spraying ammonium sulfate into the flue gases have been performed in a 96MW(th)/25MW(e) circulating fluidized bed (CFB) boiler. The boiler was fired mainly with bark and a chlorine containing waste. KCl concentration was reduced from more than 15 ppm to approximately 2 ppm. during injection of ammonium sulfate. Corrosion probe measurements indicated that both deposit formation and material loss due to corrosion were decreased using the additive. Analysis of the deposits showed significantly higher concentration of sulfur and almost no chlorine in the case with ammonium sulfate. Results from impactor measurements supported that KCl was sulfated to potassium sulfate by the additive. (C) 2007 Elsevier B.V. All rights reserved.

  • 21.
    Broström, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Kassman, Håkan
    Helgesson, Anna
    Berg, Magnus
    Andersson, Christer
    Backman, Rainer
    Nordin, Anders
    Sulphation of Corrosive Alkali Chlorides by Ammonium Sulphate in a Biomass Fired CFB Boiler2006In: Impacts of Fuel Quality on Power Production, Snowbird, Utah, USA, 2006Conference paper (Other academic)
  • 22.
    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)
  • 23. Falk, Joel
    et al.
    Berry, Robert J.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia H.
    Mass flow and variability in screw feeding of biomass powders: relations to particle and bulk properties2015In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 276, p. 80-88Article in journal (Refereed)
    Abstract [en]

    Biomass powders often have high cohesiveness, low bulk density and poor material flow characteristics which cause interruptions and variations in feeding systems. In this study, a range of biomasses – commercial charcoal, torrefied Norway spruce stem wood, non-treated Norway spruce stem wood, and reed canary grass – were milled (screen size: 1 mm) using two different methods; cutting mill and hammer mill, to form eight types of biomass powders. The powders were analyzed for loose bulk density, Hausner ratio, compression ratio, angle of repose and for size and shape distributions. Size and shape were determined by mechanical sieving and optical particle size and shape analysis. Additionally, yield loci and wall yield loci were determined through standard bulk solid testing methods. Screw feeding properties of the eight biomass powders were determined by feeding the materials in a twin screw feeder — at constant rpm and at a constant feeding rate of 1 kg/h. Correlation analysis and principal component loadings were used to describe relations between material properties and feeding characteristics. When materials were fed at a constant rpm, feeding variability was closely correlated to the powder's angle of repose (long time) and Hausner and compression ratios (short time).

  • 24.
    Falk, Joel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Larsson, Sylvia
    Sveriges Lantbruksuniversitet.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Particle properties and feeding characteristics of biomass powders2013In: European Biomass Conference and Exhibition: 21st European Biomass Conference and Exhibition, ETA-Florens Renewable Energies , 2013, p. 1160-1163Conference paper (Other academic)
    Abstract [en]

    Milling of biomass is a necessary step in the use of fuel powders and also in fuel pre-treatment. Milled biomass powders are often cohesive, have low bulk density and have poor flowability leading to costly problems in fuel handling. In this study, two different milling methods (knife mill and hammer mill) and four different biomass powders (Norway spruce, torrefied Norway spruce, charcoal and reed canary grass) were tested in order to find correlations between particle properties and feeding characteristics. The powders were analyzed for size distribution using both mechanical and optical sieveless particle size analysis. Loose and tapped bulk densities were measured to calculate the Hausner ratio, an indicator of flowability. The different powders were tested for feeding characteristics in a screw feeder at constant rpm. Hammer milling produced powders with more fines and lower densities than knife milling. Feeding performance varied between materials with two materials better when hammer milled and two better when knife milled. However, hammer milled materials had better initial feeding stability. Due to large differences in bulk density there was a large difference in feeding rates. Also, two fuels showed good agreement with the theoretical feeding rate when assuming feeding at loose bulk density while the other two showed better agreement with a flow calculated at tapped bulk density indicating different packing behaviors.

  • 25.
    Forsberg, Christer
    et al.
    Vattenfall AB Nordic Heat, S-162 87 Stockholm, Sweden .
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Edvardsson, Elin
    Vattenfall Research and Development AB, S-814 26 Älvkarleby, Sweden.
    Badiei, Shahriar
    Vattenfall Research and Development AB, S-814 26 Älvkarleby, Sweden.
    Berg, Magnus
    Vattenfall Research and Development AB, S-814 26 Älvkarleby, Sweden.
    Kassman, Håkan
    Vattenfall Power Consultant AB, Box 1046, S-611 29 Nyköping, Sweden.
    Principle, calibration, and application of the in situ alkali chloride monitor2009In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 80, no 2, p. 023104-1-023104-4Article in journal (Refereed)
    Abstract [en]

     The extended use of biomass for heat and power production has caused increased operational problems with fouling and high-temperature corrosion in boilers. These problems are mainly related to the presence of alkali chlorides (KCl and NaCl) at high concentrations in the flue gas. The In-Situ Alkali Chloride Monitor (IACM) was developed by Vattenfall Research and Development AB for measuring the alkali chloride concentration in hot flue gases (>650 oC). The measurement technique is based on molecular differential absorption spectroscopy in the UV range. Simultaneous measurement of SO2 concentration is also possible. The measuring range is 1-50 ppm for the sum of KCl and NaCl concentrations, and 4-750 ppm for SO2. This paper describes the principle of the IACM as well as its calibration. Furthermore, an example of its application in an industrial boiler is given.

  • 26.
    Holmgren, Per
    et al.
    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.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Slag formation during entrained flow gasification. Part 1: Calcium rich bark fuel2017Conference paper (Other academic)
  • 27.
    Holmgren, Per
    et al.
    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.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Slag formation during entrained flow gasification. Part 2: Silicon rich grass fuel with KHCO3 additive2017Conference paper (Other academic)
  • 28.
    Holmgren, Per
    et al.
    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.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Slag Formation during Entrained Flow Gasification: Silicon Rich Grass Fuel with KHCO3 Additive2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 10, p. 10720-10726Article in journal (Refereed)
    Abstract [en]

    Prediction of ash particle adherence to walls, melting, and flow properties are important for successful operation of slagging entrained flow gasifiers. In the present study, silicon-rich reed canary grass was gasified at 1000 and 1200 °C with solid KHCO3 added at 0, 1, or 5 wt % to evaluate the impact and efficiency of the dry mixed additive on slag properties. The fuel particles collided with an angled flat impact probe inside the hot reactor, constructed to allow for particle image velocimetry close to the surface of the probe. Ash deposit layer buildup was studied in situ as well as ash particle shape, size, and velocity as they impacted on the probe surface. The ash deposits were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy, giving detailed information on morphology and elemental composition. Results were compared to thermodynamic equilibrium calculations for phase composition and viscosity. The experimental observations (slag melting, flow properties, and composition) were in good qualitative agreement with the theoretical predictions. Accordingly, at 1000 °C, no or partial melts were observed depending upon the potassium/silicon ratio; instead, high amounts of additive and a temperature of at least 1200 °C were needed to create a flowing melt.

  • 29.
    Holmgren, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå Universitet.
    Carlborg, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå Universitet.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå Universitet.
    Slag Formation During Entrained Flow Gasification: Calcium Rich Bark Fuel with KHCO3 AdditiveManuscript (preprint) (Other academic)
    Abstract [en]

    Managing slag properties is of utmost importance for successful operation of entrained flow gasifiers. The present study details some aspects of slag formed from a softwood bark fuel, and especially the situation with only small amounts of mineral contaminants, meaning composition is shifted from Si- towards P-dominated ash. Wood bark with and without KHCO3 additive was gasified between 850 °C and 1300 °C at O2 stoichiometric ratio (λ) 0.6 to study the resulting ash properties and the influence of the additive. The ash particles collided with a flat impact probe inside the hot reactor, with particle impact angles varied between 90° to 30°. The reactor and probe were constructed to allow for long-distance microscope data collection close to the surface of the probe. In situ PIV and SEM-EDS of deposit samples from lab scale entrained flow gasification experiments were used for evaluation, while XRD was used to characterize carbonates. High potassium release was found but numerous spherical ash particles indicated lower ash melting temperatures than expected from the bulk ash composition. These new findings propose a mechanism for melt formations involving carbonates rich in potassium and phosphorous, followed by K-release and calcination leading to solidification.

  • 30.
    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)
  • 31.
    Holmgren, Per
    et al.
    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.
    Strandberg, Anna
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Molinder, Roger
    Wiinikka, Henrik
    Umeki, Kentaro
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Size, shape, and density changes of biomass particles during rapid devolatilization2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, p. 342-351Article in journal (Refereed)
    Abstract [en]

    Particle properties such as size, shape and density play significant roles on particle flow and flame propagationin pulverized fuel combustion and gasification. A drop tube furnace allows for experiments athigh heating rates similar to those found in large-scale appliances, and was used in this study to carryout experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion.The objective of this study was to develop a particle conversion model based on optical informationon particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved tothree narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized usingoptical methods. Different shape descriptors were evaluated and a shape descriptor based on particleperimeter was found to give significant information for accurate estimation of particle volume. The opticalconversion model developed was proven useful and showed good agreement with conversion measuredusing a reference method based on chemical analysis of non-volatilized ash forming elements.The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoringof particle conversion, provided density data has been calibrated.

  • 32. Kassman, Håkan
    et al.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Berg, Magnus
    Åmand, Lars-Erik
    Measures to reduce chlorine in deposits: Application in a large-scale circulating fluidised bed boiler firing biomass2011In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 90, no 4, p. 1325-1334Article in journal (Refereed)
    Abstract [en]

    Combustion of biomass with a high content of alkali (mainly potassium, K) and chlorine (Cl) can result in operational problems including deposit formation and superheater corrosion. Among the measures applied to decrease such problems are co-combustion and the use of additives. The positive effects of these measures are to a large extent either sulphation of the alkali chlorides (KCl) to less corrosive alkali sulphates or capture of alkali from KCl during release of HCl. A test campaign was carried out in a large-scale circulating fluidised boiler fired with biomass where the measures applied were sulphation by ammonium sulphate and co-combustion with peat. Their performance was evaluated by means of several advanced measurement tools including: IACM (on-line measurements of gaseous KCl); a low-pressure impactor (size distribution and chemical composition of extracted fly ash particles) and deposit measurements (chemical composition in collected deposits). The overall performance was better for ammonium sulphate, which significantly lowered KCl in the flue gas. Meanwhile no chlorine was found in the deposits. Only a minor reduction of gaseous KCl was obtained during co-combustion with peat although the chlorinecontent in the deposits was greatly reduced. These findings were supported by the results from the impactor measurements.

  • 33. Kirtania, Kawnish
    et al.
    Haggstrom, Gustav
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Umeki, Kentaro
    Furusjo, Erik
    Cogasification of Crude Glycerol and Black Liquor Blends: Char Morphology and Gasification Kinetics2017In: Energy Technology, ISSN 2194-4288, Vol. 5, no 8, p. 1272-1281Article in journal (Refereed)
    Abstract [en]

    In this study, we assessed the feasibility of black liquor/glycerol blends as a potential gasification feedstock. The char gasification reactivity and kinetics were studied at T=750, 800, 850, and 900 degrees C for 20 and 40% blends of glycerol with black liquor. Three qualities of glycerol were used including two industrial-grade crude glycerols. The gasification rates were similar for all blends; therefore, the alkali-metal catalysis is also sufficient for the char blends (alkali/C atomic ratio between 0.45 and 0.55). The blends with the most impure glycerol (containing K) had the lowest activation energies (approximate to 120 kJ mol(-1)) and reaction times for char gasification and, therefore, had fuel properties suitable for gasification. The char particles from different blends showed surface morphologies similar to those of black liquor chars with an even surface distribution of alkali elements. A loss of alkali (mainly K) from the fuel blends during pyrolysis indicated the necessity to perform gas-phase studies of alkali release. Overall, these results encourage the use of glycerol as a potential gasification feedstock for catalytic-gasification-based biorefineries.

  • 34. Lennmark-Appelbom, Daniel
    et al.
    Torshage, Erik
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    SNCR Ammonia Slip and Economizer Corrosion2018Conference paper (Other academic)
  • 35. Leppänen, A.
    et al.
    Kinnunen, H.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Enestam, Sonja
    Condensation and deposit formation in the NaCl-Na2SO4 system, an experimental and modeling study2017Conference paper (Other academic)
  • 36. Mäkelä, Mikko
    et al.
    Wai Kwong, Chi
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yoshikawa, Kunio
    Hydrothermal treatment of grape marc for solid fuel applications2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 145, p. 371-377Article in journal (Refereed)
    Abstract [en]

    The treatment and disposal of grape marc, a residue from grape processing, represents a significant economic and environmental challenge for the winemaking industry. Hydrothermal treatment of grape marc could be an efficient way for producing solid fuels on-site at the wineries. In this work the effects of treatment temperature and liquid pH on grape marc char and liquid properties were determined based on laboratory experiments and the combustion characteristics of char were assessed through thermogravimetric analysis and fuel ash classification. The results showed that hydrothermal treatment increased the energy and carbon contents and decreased the ash content of grape marc. The effect of liquid pH was statistically significant (p < 0.05) only for the determined carbon yield of liquid samples. The energy yield from grape marc was maximized at lower treatment temperatures, which also decreased the content of less thermally stable compounds in the attained char. Higher treatment temperatures decreased grape marc solid, carbon and energy yields and led to an increase in thermally labile compounds compared to lower temperatures likely due to the condensation of liquid compounds or volatiles trapped in the pores of char particles. The alkali metal contents of char ash were reduced coupled with an increase in respective phosphorus. Overall the results support the use of hydrothermally treated grape marc in solid fuel applications, if elevated levels of ash phosphorus can be tolerated.

  • 37. 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.

  • 38. 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.

  • 39.
    Persson, Anna
    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.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Decomposition modeling using thermogravimetry with a multivariate approach2013In: European Biomass Conference and Exhibition Proceedings: 21st European Biomass Conference and Exhibition, ETA-Florens Renewable Energies , 2013, p. 1451-1455Conference paper (Other academic)
    Abstract [en]

    There exists a need for simple and reliable characterization methods for biomass in several scientific areas. Not many publications report on multivariate statistical treatment of thermogravimetric data, and therefore the objectives of this study were to i) evaluate the potential for using a multivariate statistical approach for modeling degree of decomposition of thermally pretreated wood using data from conventional thermogravimetric analysis, ii) compare the predictions from the multivariate chemometric model with a gaussian curve fit approach made to the same data set, and iii) demonstrate the method comparison also for torrefied material from a pilot scale torrefaction plant, an application with relevance for bio-based energy systems under development. The results showed that the suggested method for decomposition modeling performed well, even though some limitations were discovered. It was also proven useful for the application tested.

  • 40.
    Persson, Kristoffer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Carlsson, Jörgen
    Umeå Energi AB, Box 224, 901 05 Umeå, Sweden.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    High temperature corrosion in a 65 MW waste to energy plant2007In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 88, no 11-12, p. 1178-1182Article in journal (Refereed)
    Abstract [en]

    Incineration of municipal solid waste is often associated with high temperature corrosion problems. This paper presents results of full-scale corrosion tests in a 65 MW waste fired combined heat and power plant. A failure case indicated alarmingly high corrosion rate of the superheater tubes. Corrosion tests with five different alloys were carried out within this work in order to determine plant specific corrosion rates on different superheater materials. Additional tests were done to determine the effect on the corrosion rate from adding chlorine containing polyvinyl chloride to the ordinary fuel mix. A corrosion probe with metal temperatures ranging from 320 degrees C to 460 degrees C was used to estimate corrosion loss and to collect deposits. The sampling was performed at a flue gas temperature of 470 degrees C for 10 days. The probe rings were analysed using scanning electron microscope and micrometer measurements to determine the deposit chemistry and corrosion rates. The results showed significant differences in corrosion rates depending on tube material. Chlorine was shown to have a key role in the corrosion process, even at these relatively low temperatures. The results indicated a chlorine induced corrosion mechanism involving volatile iron chloride with a high corrosion rate on the superheater materials typically used. Addition of extra polyvinyl chloride to the fuel mix had an increasing effect on the corrosion. (C) 2007 Elsevier B.V. All rights reserved.

  • 41. Persson, Kristoffer
    et al.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Carlsson, Jörgen
    Nordin, Anders
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    High Temperature Corrosion in a 65 MW Waste-to-Energy Plant2006Conference paper (Other academic)
  • 42. Phounglamcheik, Aekjuthon
    et al.
    Wang, Liang
    Romar, Henrik
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Ramser, Kerstin
    Skreiberg, Øyvind
    Umeki, Kentaro
    Effects of pyrolysis oil recycling and reaction gas atmosphere on the physical properties and reactivity of charcoal from wood2018In: 22nd International Symposium on Analytical and Applied Pyrolysis, 2018Conference paper (Other academic)
  • 43.
    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.

  • 44.
    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.

  • 45.
    Qu, Zhechao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Holmgren, Per
    Skoglund, Nils
    Wagner, David R.
    Broström, Markus
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Investigation of H2O, temperature and potassium in entrained flow biomass combustion – coupling in situ TDLAS with modelling2017In: Nordic Flame Days 2017, 10-11 October, Stockholm, 2017Conference paper (Refereed)
  • 46.
    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.
    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.
    TDLAS-based in situ detection of atomic potassium during combustion of biomass in an entrained flow reactor2016Conference paper (Other academic)
  • 47.
    Salehi, Shahrbanoo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Skoglund, Nils
    Energy Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology.
    Backman, Rainer
    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.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Investigation of phase diagram with relevance for thermal conversion of biomass2014In: KBC-days, Umeå university, 2014Conference paper (Other academic)
  • 48.
    Sandström, Karin
    et al.
    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.
    Weidemann, Eva
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Fluorine reactions in MSW combustion2019In: EUBCE 2019, 2019Conference paper (Other academic)
    Abstract [en]

    Fluorine is of increasing concern in waste combustion since fluorinated plastics constitute anincreasing share of waste fractions entering CHP plants. Alkali fluorides could potentially causesimilar problems as are well known for the corresponding chlorides. However, there are somefundamental differences in thermodynamic stabilities. Available literature essentially lacks theexperimental evidence needed to draw any further conclusions on the extent of any fluorine relatedproblems, but recently a MSW fired CHP reported alarming deposit growth rates, possibly relatedto a delivery of fluorine containing fuels. The objective of the present study was to experimentallyevaluate some of the thermodynamic considerations mentioned. Fuels were prepared by addingNaCl, NaF and S to softwood pellets. Deposit and aerosol samples were analyzed with SEM-EDSand XRD, and evaluated together with fundamental thermodynamic phase equilibriumconsiderations to provide new and important information on the ash forming reactions and theirimplications. The results from the combustion tests showed that the fluorine found on the depositprobe was in form of NaF and Na3F(SO4) in qualitative agreement with thermodynamicequilibrium calculations.

  • 49.
    Sandström, Karin
    et al.
    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.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Nordkalk AB.
    Estimating ash properties for new fuels in calcination kilns2019Conference paper (Other academic)
  • 50.
    Sandström, Karin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Weidemann, Eva
    Boman, Christoffer
    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.
    Fluorides in Deposits2018Conference paper (Other academic)
12 1 - 50 of 79
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