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  • 1.
    Andersson, Sven R.
    et al.
    Götaverken Miljö AB, Sweden.
    Blomqvist, Evalena W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Bäfver, Linda S.
    RISE, SP – Sveriges Tekniska Forskningsinstitut. Pöyry SwedPower AB, Sweden.
    Jones, Frida
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Froitzheim, Jan
    Chalmers University of Technology, Sweden.
    Karlsson, Martin
    Götaverken Miljö AB, Sweden.
    Larsson, Erik
    Chalmers University of Technology, Sweden.
    Liske, J.
    Chalmers University of Technology, Sweden.
    Sulfur recirculation for increased electricity production in Waste-to-Energy plants2014In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 1, p. 67-78Article in journal (Refereed)
    Abstract [en]

    Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Göteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop.The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO3 concentrations, which may otherwise induce low temperature corrosion.In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450. °C and 525. °C) compared to the reference exposure. The corrosion rates were reduced by 60-90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525. °C with sulfur recirculation in operation were similar or lower compared to those measured at 450. °C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion.

  • 2.
    Atongka Tchoffor, Placid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik. Chalmers University of Technology, Sweden.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Thunman, Henrik
    Chalmers University of Technology, Sweden.
    Effects of Steam on the Release of Potassium, Chlorine, and Sulfur during Char Conversion, Investigated under Dual Fluidized Bed Gasification Conditions2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 11, p. 6953-6965Article in journal (Refereed)
    Abstract [en]

    The corrosion and fouling of heat-transfer surfaces and the agglomeration of bed materials in fluidized beds are some of the ash-related problems caused by the transformation and release to the gas phase of ash-forming elements from biomass during thermochemical conversion processes. The magnitudes of these problems are largely dependent upon the release of potassium (K), chlorine (Cl), and sulfur (S) from the biomass. We investigated the effects of steam on the release of K, Cl, and S during char conversion, under conditions relevant for dual-fluidized-bed gasification (DFBG). The study was carried out with wheat straw in a laboratory-scale bubbling fluidized-bed reactor in the temperature range of 800-900 °C. The release of K, Cl, and S from wheat straw during devolatilization, char gasification, and char combustion was quantified with a mass balance that linked the masses of these elements in the wheat straw to the mass of the solid residue obtained at the end of each experiment. To facilitate analyses of the experimental results, leaching and the Brunauer-Emmett-Teller surface area measurement of the wheat straw and some of the solid residues were carried out. The results show that, during devolatilization, the release of volatile salts, e.g., KCl, is significantly limited by intraparticle diffusion resistance, owing to a compact char matrix (i.e., negligible porosity). However, during char gasification, steam renders the char less compact by expanding and/or creating new pores in the char. As a result, intraparticle diffusion resistance decreases, thereby facilitating the evaporation of volatile salts of K and S from the char matrix. The conversion of the char is also conducive to the release of char-bound K and S, especially at 900 °C. At temperatures of >800 °C, the relative proportions of the elements released and char gasified indicate that the release of K can somewhat be decoupled from the release of S and Cl by maximizing the extent of char conversion in the gasification chamber. The results also show that, during char combustion, the proportions of the char that can be combusted and the extent of the release of the elements are influenced by the extent to which the char is gasified in the gasification chamber.

  • 3.
    Atongka Tchoffor, Placid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik. Chalmers University of Technology, Sweden.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Thunman, Henrik
    Chalmers University of Technology, Sweden.
    Transformation and Release of Potassium, Chlorine, and Sulfur from Wheat Straw under Conditions Relevant to Dual Fluidized Bed Gasification2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 12, p. 7510-7520Article in journal (Refereed)
    Abstract [en]

    The release and transformation of potassium (K), chlorine (Cl), and sulfur (S) from biomass during thermochemical conversion processes may lead to problems, such as the corrosion and fouling of heat transfer surfaces, agglomeration of bed material, and the poisoning of catalysts used in the downstream processes of gasifiers. To predict and to mitigate effectively these problems, information regarding the quantity and mechanism of the release of these elements under relevant operating conditions is required. In the present work, the release of K, Cl, and S from wheat straw under conditions relevant to dual fluidized bed gasification were quantified in a laboratory-scale bubbling fluidized bed reactor. During the pyrolysis step, the bed temperature ranged from 550 to 900 C, while the residence time for the fuel in the reactor was fixed at 3 min. The char samples obtained from the pyrolysis step were partially combusted at the same temperature at which they were produced for an additional 3 min. The fractions of the elements released from the fuel were quantified by chemical analysis of the char/residual ash obtained in each experiment and a mass balance across the system. Overall, 75%-62% of the Cl, 59%-67% of the S, and 14%-31% of the K in the virgin wheat straw were released during pyrolysis conducted within the investigated temperature range. The char obtained from the pyrolysis process contained significantly higher amounts of K, Cl, and S than the virgin fuel. Furthermore, the ash content of the char was about 5-fold higher than that of the virgin fuel. This suggests that at combustion-relevant temperatures, complete combustion of the char is more likely to result in severe ash-related problems than combustion of the virgin fuel. Partial combustion of the char resulted in additional release of K, Cl, and S. In addition to the experimental results, the transformation and release of the elements during this process are discussed with the aid of chemical thermodynamic equilibrium modeling and leaching.

  • 4.
    Dahlbom, Sixten
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Johansson, Inge
    RISE Research Institutes of Sweden.
    Jonasson, Anna
    E.ON., Sweden.
    Vatten RUI, Marius Haakon
    NOAH.
    Sjöblom, Rolf
    Tekedo, Sweden.
    Östrem, Sofie
    Linköping University, Sweden.
    Minimering av vätgasrelaterade risker från avfallseldade CFB-pannor2020Report (Other academic)
    Abstract [en]

    There are operating parameters that affect the hydrogen formation from APC-residues generated in waste fired CFB-boilers. There are also reasons to be careful and take extra consideration to safety aspects in environments where the APC-residue has been exposed to water. It is well known that if the APC-residues generated from waste fired CFB-boilers are exposed to water; hydrogen gas is formed. The overall aim of the project has been to decrease the work environment hazards related to hydrogen formation from these APC-residues. Another aim has also been to increase the general knowledge related to these hydrogen related hazards. This has been accomplished by exploring which operating parameters and general mechanisms that affect the hydrogen formation from the APC-residues. Both total amount of gas formed as well as the velocity of the gas formation has been of interest. The APC-residues used in this project have been from P14 and P15 at the waste-to-energy plant Händelöverket, owned and operated by E.ON. In literature there are almost no publications on the hydrogen gas formation from APC residues generated by waste fired CFB boilers. There are some related to waste fired grate boilers though. Conclusions and theories from literature data must be put together from results regarding similar materials in totally different environments. The experimental results indicate a difference in the hydrogen formation from APCresidues originating from P14 and P15. The bed material used in the boilers is also one of the operational parameters that seems to affect the reactivity of the APCresidue. The introduction of a share of Ilmenite in the bed material seems to have lowered the amount of hydrogen gas formed, alternatively it delayed the formation. Other operational conditions that was considered was a decreased thermal load, lowered amount of ammonia added to reduce NOx, and storage/aging of ash in the NID-reactor while it was not running on full capacity. There are indications that these conditions also affect the reactivity, however there are too few data available to make specific conclusions. In general, it seems difficult to control the reactivity of the APC-residue while keeping normal production in the plant. In fouling samples, from different parts of the boilers, levels of metallic aluminium fully comparable to those in the APC-residue were detected. Thus, there is a significant risk of hydrogen formation when using wet cleaning methods during maintenance stops. Proper ventilation and education are two of the recommendations to mitigate the risks. A potential logistic chain for APC-residues, based on ship transports, was risk assessed. Since the hydrogen formation differs greatly between different ash deliveries, an important conclusion was that it is hazardous to generalise the results, especially by using average hydrogen formation rates. Another conclusion was that consideration must be made for the fact that the hydrogen formation might be delayed and might not arise until the APC-residue is treated mechanically

  • 5.
    Davidsson, Kent
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Feiler, Adam
    Corkery, Robert
    Bäfver, Linda
    Glatta ytor: En genomngång av glatta ytor som teknik för att stå emot bildning av beläggningar på värmeöverförande ytor2012Report (Refereed)
  • 6.
    Davidsson, Kent
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Johansson, Inge
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Stålenheim, Annika
    Vattenfall, Sweden.
    Boman, Katarina
    Vattenfall, Sweden.
    Sotningsmetoder för pannor som använder besvärliga bbränslen2014Report (Other academic)
    Abstract [sv]

    Erfarenheter samt finansierings- och driftkostnader har tagits fram för en rad

    sotningsmetoder.

    Resultatet visar att av de studerade anläggningarna finns det ingen metod som generellt

    bara fungerar bra, eller generellt inte fungerar alls. Alla har sina för och nackdelar och

    fungerar olika bra på olika pannor. Kostnadsmässigt är det också stor spridning men det

    beror delvis på ett ganska litet underlag. I vissa fall blir kostnaderna väldigt höga om

    bristande funktion leder till mycket stilleståndstid eller att man exempelvis får minska

    lasten under sotningssekvensen, medan det i andra fall är relativt låga kostnader för

    samma metod.

    Ett trettiotal anläggningar av rost- och fluidbäddtyp, vilka eldades med avfall eller

    biobränsle har ingått i undersökningen.

  • 7.
    Davidsson, Kent
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Jones, Frida
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Niklasson, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Ryde, Daniel
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Gustafsson, Göran
    Herstad, Solvie
    Askans betydelse för rötslams goda samförbränningsegenskaper2012Report (Refereed)
  • 8.
    Gall, Dan
    et al.
    University of Gothenburg, Sweden.
    Pushp, Mohit
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Larsson, Anton
    Göteborg Energi AB, Sweden.
    Davidsson, Kent
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Pettersson, Jan B. C.
    University of Gothenburg, Sweden.
    Online Measurements of Alkali Metals during Start-up and Operation of an Industrial-Scale Biomass Gasification Plant2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 1, p. 532-541Article in journal (Refereed)
    Abstract [en]

    Alkali metal compounds may have positive influences on biomass gasification by affecting char reactivity and tar reforming but may also disturb the process by formation of deposits and agglomerates. We herein present results from online measurements of alkali compounds and particle concentrations in a dual fluidized bed gasifier with an input of 32 MWth. A surface ionization detector was used to measure alkali concentrations in the product gas, and aerosol particle measurement techniques were employed to study concentrations and properties of condensable components in the gas. Measurements were performed during start-up and steady-state operation of the gasifier. The alkali concentration increased to approximately 200 mg m-3 when fuel was fed to the gasifier and continued to rise during activation of the olivine bed by addition of potassium carbonate, while the alkali concentration was in the range from 20 to 60 mg m-3 during steady-state operation. Addition of fresh bed material and recirculated ash had noticeable effects on the observed alkali concentrations, and K2CO3 additions to improve tar chemistry resulted in increased levels of alkali in the product gas. Addition of elemental sulfur led to reduced concentrations of CH4 and heavy tars, while no clear influence on the alkali concentration was observed. The study shows that alkali concentrations are high in the product gas, which has implications for the fluidized bed process, tar chemistry, and operation of downstream components including coolers, filters, and catalytically active materials used for product gas reforming.

  • 9. Gyllenhammar, Marianne
    et al.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Hermansson, Sven
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Svärd, Solvie
    Larsson, Erik
    Jonsson, Torbjörn
    Zhao, Dongmei
    Liske, Jesper
    Additiv för att minska driftproblem vid rostförbränning av avfall2013Report (Other (popular science, discussion, etc.))
  • 10.
    Henriksson, Gunilla
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Palm, Ola
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Ljung, Emelie
    RISE Research Institutes of Sweden.
    Sager, Anna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Rätt slam på rätt plats2012Report (Refereed)
  • 11.
    Janhäll, Sara
    et al.
    RISE Research Institutes of Sweden, Built Environment, Energy and Resources.
    Petersson, Mikaela
    Lund University, Sweden.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Öman, Tommy
    RISE Research Institutes of Sweden.
    Sommertune, Jens
    RISE Research Institutes of Sweden.
    Kåredal, Monica
    Lund University, Sweden.
    Messing, Maria E.
    Lund University, Sweden.
    Rissler, Jenny
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Lund University, Sweden.
    Release of carbon nanotubes during combustion of polymer nanocomposites in a pilot-scale facility for waste incineration2021In: NanoImpact, ISSN 2452-0748, Vol. 24, article id 100357Article in journal (Refereed)
    Abstract [en]

    Nanocomposites, formed by incorporating nanoparticles into a matrix of standard materials, are increasing on the market. Little focus has been directed towards safe disposal and recycling of these new materials even though the disposal has been identified as a phase of the products' life cycle with a high risk of uncontrolled emissions of nanomaterials. In this study, we investigate if the carbon nanotubes (CNTs), when used as a filler in two types of polymers, are fully destructed in a pilot-scale combustion unit designed to mimic the combustion under waste incineration. The two polymer nanocomposites studied, polycarbonate (PC) with CNT and high-density polyethylene (HDPE) with CNT, were incinerated at two temperatures where the lower temperature just about fulfilled the European waste incineration directive while the upper was chosen to be on the safe side of fulfilling the directive. Particles in the flue gas were sampled and analysed with online and offline instrumentation along with samples of the bottom ash. CNTs could be identified in the flue gas in all experiments, although present to a greater extent when the CNTs were introduced in PC as compared to in HDPE. In the case of using PC as polymer matrix, CNTs were identified in 3–10% of the analysed SEM images while for HDPE in only ~0.5% of the images. In the case of PC, the presence of CNTs decreased with increasing bed temperature (from 10% to 3% of the images). The CNTs identified were always in bundles, often coated with remnants of the polymer, forming particles of ~1–4 μm in diameter. No CNTs were identified in the bottom ash, likely explained by the difference in time when the bottom ash and fly ash are exposed to high temperatures (~hours compared to seconds) in the pilot facility. The results suggest that the residence time of the fly ash in the combustion zone is not long enough to allow full oxidation of the CNTs. Thus, the current regulation on waste incineration (requiring a residence time of the flue gas >850 °C during at least 2 s) may not be enough to obtain complete destruction of CNTs in polymer composites. Since several types of CNTs are known to be toxic, we stress the need for further investigation of the fate and toxicity of CNTs in waste treatment processes.

  • 12.
    Kong, Xiangrui
    et al.
    University of Gothenburg, Sweden.
    Salvador, Christian
    University of Gothenburg, Sweden.
    Carlsson, Staffan
    RISE Research Institutes of Sweden.
    Pathak, Ravikant
    University of Gothenburg, Sweden.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Built Environment, Energy and Resources.
    Le Breton, Michael
    University of Gothenburg, Sweden.
    Gaita, Samuel
    University of Gothenburg, Sweden.
    Mitra, Kalyan
    University of Gothenburg, Sweden.
    Hallquist, Åsa
    IVL Swedish Environmental Research Institute, Sweden.
    Hallquist, Mattias
    University of Gothenburg, Sweden.
    Pettersson, Jan
    University of Gothenburg, Sweden.
    Molecular characterization and optical properties of primary emissions from a residential wood burning boiler2021In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 754, article id 142143Article in journal (Refereed)
    Abstract [en]

    Modern small-scale biomass burners have been recognized as an important renewable energy source because of the economic and environmental advantages of biomass over fossil fuels. However, the characteristics of their gas and particulate emissions remain incompletely understood, and there is substantial uncertainty concerning their health and climate impacts. Here, we present online measurements conducted during the operation of a residential wood-burning boiler. The measured parameters include gas and particle concentrations, optical absorption and chemical characteristics of gases and particles. Positive matrix factorization was performed to analyze data from a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) equipped with a filter inlet for gases and aerosols (FIGAERO). Six factors were identified and interpreted. Three factors were related to the chemical composition of the fuel representing lignin pyrolysis products, cellulose/hemicellulose pyrolysis products, and nitrogen-containing organics, while three factor were related to the physical characteristics of the emitted compounds: volatile compounds, semi-volatile compounds, and filter-derived compounds. An ordinal analysis was performed based on the factor fractions to identify the most influential masses in each factor, and by deconvoluting high-resolution mass spectra fingerprint molecules for each factor were identified. Results from the factor analysis were linked to the optical properties of the emissions, and lignin and cellulose/hemicellulose pyrolysis products appeared to be the most important sources of brown carbon under the tested burning conditions. It is concluded that the emissions from the complex combustion process can be described by a limited set of physically meaningful factors, which will help to rationalize subsequent transformation and tracing of emissions in the atmosphere and associated impacts on health and climate. 

  • 13.
    Lundberg, Louise
    et al.
    Chalmers University of Technology, Sweden.
    Atongka Tchoffor, Placid
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Pallarès, David
    Chalmers University of Technology, Sweden.
    Thunman, Henrik
    Chalmers University of Technology, Sweden.
    Davidsson, Kent
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Impacts of Bed Material Activation and Fuel Moisture Content on the Gasification Rate of Biomass Char in a Fluidized Bed2019In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, no 12, p. 4802-4809Article in journal (Refereed)
    Abstract [en]

    The use of certain bed materials has been found to increase the steam gasification rate of biomass char. The present work investigates how this phenomenon is influenced by different parameters (e.g., temperature, fuel type, and fuel moisture content), using a laboratory-scale bubbling fluidized bed gasifier. Silica sand, fresh olivine, and activated olivine were employed as bed materials, and three biomass fuels (wood chips, wood pellets, and forest residue pellets) were considered. Switching the bed material from silica sand to activated olivine resulted in a significant increase in the char gasification rate for all three fuels, with further increases noted as the fuel particle size was decreased. The observed effect was strongest (up to 4-fold) during the initial conversion phase (char gasification degrees < 20%) when the temperature was relatively low (≤ 800 °C). The moisture content of the wood chips (0-40%) had no significant effect on the char gasification rate.

  • 14.
    Lundberg, Louise
    et al.
    Chalmers University of Technology, Sweden.
    Tchoffor, Placid A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Pallares, David
    Chalmers University of Technology, Sweden.
    Johansson, Robert
    Chalmers University of Technology, Sweden.
    Thunman, Henrik
    Chalmers University of Technology, Sweden.
    Davidsson, Kent
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Influence of surrounding conditions and fuel size on the gasification rate of biomass char in a fluidized bed2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 144, p. 323-333Article in journal (Refereed)
    Abstract [en]

    While the operational conditions of a fluidized bed are known to influence the fuel axial mixing, the effect of the resulting axial location of the fuel particles on the char gasification rate remains unexplored. In this work, a laboratory-scale bubbling fluidized bed was used to investigate how the gasification rate of biomass char was influenced by the fuel axial location (during pyrolysis and char gasification), the pyrolysis atmosphere, the fuel size, and the fuel concentration. When pyrolysis at the bed surface was followed by char gasification inside the dense bed the char gasification rate was up to 2-fold lower than the other combinations of the fuel axial location, which held similar rates. Cooling the char after pyrolysis decreased the char gasification rate in all cases studied. The gasification rate increased when the fuel particle size was decreased, and its dependence on the degree of char conversion was also affected. Thus, the operational conditions of a fluidized bed reactor, through modified fuel axial mixing, can influence the char gasification rate. Furthermore, experimental determination of reactivity data in laboratory-scale systems must account for the axial location of the fuel at the desired end-scale, using similar fuel particle sizes.

  • 15.
    Lönnermark, Anders
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Persson, Henry
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Hedenstedt, Anders
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Jones, Frida
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Davidsson, Kent
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Johansson, Inge
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Boström, Sara
    Sweco, Sweden.
    Rekommendation för proaktivt brandskyddsarbete2019Report (Other academic)
  • 16.
    Priestley, Michael
    et al.
    University of Gothenburg, Sweden.
    Kong, Xiangrui
    University of Gothenburg, Sweden.
    Pei, Xiangyu
    University of Gothenburg, Sweden.
    Pathak, Ravi K.
    University of Gothenburg, Sweden.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Pettersson, Jan B. C.
    University of Gothenburg, Sweden.
    Hallquist, Mattias
    University of Gothenburg, Sweden.
    Volatility Measurements of Oxygenated Volatile Organics from Fresh and Aged Residential Wood Burning Emissions2023In: ACS Earth and Space Chemistry, E-ISSN 2472-3452Article in journal (Refereed)
    Abstract [en]

    Residential wood combustion (RWC) is a dominant source of anthropogenic aerosol in urban areas. Complexities in aerosol chemical composition, semivolatile behavior, and secondary processing make estimating RWC impacts on climate and air quality challenging. A chemical ionization mass spectrometer with a filter inlet for gas and aerosols measured the gas-to-particle partitioning of organic compounds emitted from log wood and pellet burning stoves. Emissions were aged in an oxidation flow reactor to assess changes in the volatilities of the secondary aerosol. Effective saturation vapor concentrations (C*) of the measured species were derived using both the measured particle-to-gas concentration ratio (Pi/Gi) and vapor pressure measurements (pi0) calibrated using the maximum temperature during evaporation. These were used to derive new molecular formula (MF) parameterizations and were compared to selected previous parameterization. The fresh wood stove emissions were less volatile than those of the pellet stove (particle fractions of 0.96 vs 0.69), likely caused by poorer combustion conditions, producing a greater particle sink for organic vapors. After aging, the volatility of the emissions remained broadly similar, whereas all MF parameterizations showed increasing volatility. This was likely due to the measurement techniques capturing nonideal effects of partitioning that MF parameterizations cannot.

  • 17.
    Pushp, Mohit
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Safety. University of Gothenburg, Sweden.
    Brackmann, Christian
    Lund University, Sweden.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy. University of Gothenburg, Sweden.
    Infrared Spectroscopy for Online Measurement of Tars, Water, and Permanent Gases in Biomass Gasification2021In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 75, no 6, p. 690-697Article in journal (Refereed)
    Abstract [en]

    Online measurements of the raw gas composition, including tars and water, during biomass gasification provide valuable information in fundamental investigations and for process control. Mainly consisting of hydrocarbons, tars can, in principle, be measured using Fourier transform infrared (FT-IR) spectroscopy. However, an instrument subjected to raw gas runs the risk of condensation of tars on optical components and subsequent malfunction. Therefore, an external cell, heated to at least 400 ℃, has been designed to ensure that tars remain in the gas phase during FT-IR measurements. The cell was used for on-line FT-IR measurements of permanent gases (CO, CO2, CH4), water, and tars during the operation of a lab-scale downdraft gasifier using wood pellets, bark pellets, and char chips. Based on calibration, the measurement error of permanent gases was estimated to be 0.2%. Concentrations evaluated from spectral signatures of hydrocarbons in tar are in good agreement with results from solid-phase adsorption measurements and correlated well with operational changes in the gasifier. 

  • 18.
    Pushp, Mohit
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Gall, Dan
    University of Gothenburg, Sweden.
    Davidsson, Kent
    RISE - Research Institutes of Sweden (2017-2019), Built Environment, Energy and Circular Economy.
    Seemann, Martin
    Chalmers University of Technology, Sweden.
    Pettersson, Jan B C
    University of Gothenburg, Sweden.
    Influence of Bed Material, Additives, and Operational Conditions on Alkali Metal and Tar Concentrations in Fluidized Bed Gasification of Biomass2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 6, p. 6797-6806Article in journal (Refereed)
    Abstract [en]

    Gasification of biomass results in release of tar and alkali metal compounds that constitute a significant challenge to the optimization of the gasification process. Here we describe on-line measurements of alkali, condensable tar, and particle concentrations in product gas from a 2-4 MWth dual fluidized bed gasifier, with the aims to characterize typical concentrations and contribute to the understanding of alkali-tar interactions. The influence of bed material, additives, and operational parameters on the concentrations is investigated. Alkali concentrations are measured with a surface ionization detector, and particle and tar concentrations are determined using aerosol measurement techniques. The gasification of wood chips using quartz or olivine as bed material results in an alkali concentration of 30-250 mg m-3, and the observed alkali levels are consistent with a significant release of the fuel alkali content. Addition of ilmenite to a quartz bed and additions of K2SO4 and K2CO3 to an olivine bed influence both alkali and heavy tar concentrations. The additions result in changes in alkali concentration that relaxes to a new steady state in tens of minutes. The concentration of condensable tar is lower for the olivine bed than for the quartz bed, and tends to decrease when potassium or sulfur is added. The concentration of condensable tar compounds is anticorrelated with the alkali concentration when a quartz bed is used, while no clear trend is observed with an olivine bed. An increase in steam flow rate results in a substantial decrease in heavy tar concentration from a quartz sand bed, while the alkali concentration increases slightly with increasing flow rate. This is in contrast to the alkali concentrations observed when using an activated olivine bed, where concentrations are higher and tend to decrease with increasing steam flow rate. The study confirms that several primary methods are available to optimize the alkali and tar behavior in the gasifier, and suggests that on-line monitoring is needed to systematically change the operational conditions and to study the underlying processes.

  • 19.
    Råberg, Tora
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Lorentzon, Katarina
    RISE Research Institutes of Sweden, Built Environment, System Transition and Service Innovation.
    Västerdal, Mårten
    RISE Research Institutes of Sweden.
    Pettersson Skog, Anna
    RISE Research Institutes of Sweden, Built Environment, Infrastructure and concrete technology.
    Cristescu, Carmen
    RISE Research Institutes of Sweden, Built Environment, Building and Real Estate.
    Davidsson, Kent
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Schouenborg, Björn
    RISE Research Institutes of Sweden, Built Environment, Infrastructure and concrete technology.
    Atongka Tchoffor, Placid
    RISE Research Institutes of Sweden, Built Environment, Infrastructure and concrete technology.
    Potentiella kolsänkor i Malmö stad2022Report (Other academic)
    Abstract [sv]

    Miljöförvaltningen inom Malmö stad gav RISE uppdraget att identifiera möjligheter att öka kolsänkorna inom kommungränsen. Syftet med den här rapporten är att sammanställa ett brett underlag för klimatarbete med åtgärder som möjliggör en ökning av de lokala kolsänkorna i Malmö stads geografiska område. Genom att uppskatta olika åtgärders potential för kolinlagring, teknisk mognadsgrad och kostnadseffektivitet från ett klimatperspektiv, samt visa på vilka skalor det går att jobba med dessa åtgärder inom kommunen, avses rapporteringen ge en översikt över vilka satsningar som kan göras för att kolsänkorna ska kunna bidra till Malmö stads miljö- och klimatmål. Forskargruppen från RISE har analyserat 18 olika kategorier som har potential att öka den lokala kolinlagringen inom: • de urbana grönområdena, • den urbana infrastrukturen, bebyggd mark och tillhörande mark • rural markanvändning och • övriga möjligheter. I beräkningarna ingår inte klimatpåverkan från insatser som krävs för att genomföra åtgärderna, till exempel avverkning, uppdrivning och plantering av skogsplantor, transport av timmer och förädling av virke. I rapporten tas inte hänsyn till om en ökad användning av mark i en kategori, minskar markanvändning inom en annan kategori.

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