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  • 1.
    Alipour, Yousef
    et al.
    KTH Royal Institute of Technology, Sweden.
    Talus, Annika
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Henderson, Pamela
    KTH Royal Institute of Technology, Sweden; Vattenfall AB, Sweden.
    Norling, Rikard
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    The effect of co-firing sewage sludge with used wood on the corrosion of an FeCrAl alloy and a nickel-based alloy in the furnace region2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, p. 805-813Article in journal (Refereed)
    Abstract [en]

    The effect of digested sewage sludge as a fuel additive to reduce corrosion of furnace walls has been studied. The nickel base alloy Alloy 625 and the iron-chromium-aluminium alloy Kanthal APMT™ were exposed for 14.25. h at the furnace wall in a power boiler burning 100% used (also known as waste or recycled) wood. The test was then repeated with the addition of sewage sludge to the waste wood. The samples were chemically analysed and thermodynamically modelled and the corrosion mechanisms were investigated. The results showed that the co-firing of sewage sludge with recycled wood leads to a reduction in the corrosion. Attack by a potassium-lead combination appeared to be the main corrosion mechanism in Alloy 625 during waste wood combustion, while attack by alkali chloride was found to be dominant in APMT alloy.

  • 2. Berghel, J.
    et al.
    Frodeson, S.
    Granström, K.
    Renström, R.
    Stahl, M.
    Nordgren, D.
    RISE, Innventia.
    Tomani, P.
    RISE, Innventia.
    The effects of kraft lignin additives on wood fuel pellet quality, energy use and shelf life2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, p. 64-69Article in journal (Refereed)
  • 3.
    Celaya Romeo, Javier
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Wernersson Brodin, Fredrik
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Re-homogenization of phase separated forest residue pyrolysis oil by blending2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 163, p. 60-66Article in journal (Refereed)
    Abstract [en]

    The wood processing industry generates large amounts of forest residues like branches and tops which represent a significant unexploited resource for sustainable biofuel production. A feasible thermochemical route to valorise these residues is fast pyrolysis. However, the main product of this technology, pyrolysis oil or bio-oil, shows several disadvantages in comparison with conventional fuels. One of the main drawbacks of bio-oil is its instability which results in liquid phase separation in many cases. The purpose of this study is to verify whether homogenous single-phase heating fuels for district heating etc. can be formed from aged, phase separated forest residue pyrolysis oils by blending. Aged, phase separated pyrolysis oils were blended with either methanol or 1-butanol and the amount of alcohol needed to form homogeneous and storage stable fuel blends was evaluated. Homogeneity of the fuel blends was analysed by water concentration profile analysis and image analysis. Storage stability was analysed by analysing homogeneity as function of storage time. Essential fuel characteristics were analysed. The results revealed that phase separated forest residue pyrolysis oil can be homogenized by adding moderate amounts of alcohol and that some of the blends are stable longer than two months. Alcohol addition also improves essential product properties for pyrolysis oils as heating fuels. This work forms part of the ReShip Project partly funded by the Research Council of Norway (The ENERGIX programme).

  • 4.
    Göktepe, Burak
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    Gebart, Rikard
    Luleå University of Technology, Sweden.
    Does distance among biomass particles affect soot formation in an entrained flow gasification process?2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 141, p. 99-105Article in journal (Refereed)
    Abstract [en]

    Soot creates technical challenges in entrained flow biomass gasification processes, e.g. clogging of flow passages, fouling on system components and reduced efficiency of gasification. This paper demonstrates a novel soot reduction method in a laboratory-scale entrained flow reactor by forced dispersion of biomass particles. Gasification of small biomass particles was done in a flat flame burner where a steady stream of biomass was sent. The flat flame burner was operated with a premixed sub-stoichiometric methane-air flame to simulate the conditions in an entrained flow gasifier. The dispersion of biomass particles was enhanced by varying the flow velocity ratio between particle carrier gas and the premixed flame. Primary soot particles evolved with the distance from the burner exit and the soot volume fraction was found to have a peak at a certain location. Enhanced particle separation diminished the peaks in the soot volume fraction by 35-56% depending on the particle feeding rates. The soot volume fraction was found to decrease towards an asymptotic value with increasing inter-particle distance.

  • 5. Haggstrom, C.
    et al.
    Ohrman, O.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Rownaghi, A.A.
    Hedlund, J.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Catalytic methanol synthesis via black liquor gasification2012In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 94, no 1Article in journal (Refereed)
    Abstract [en]

    Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16-0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C 4, ethanol and dimethyl ether. © 2011 Elsevier B.V. All rights reserved.

  • 6.
    Johansson, Ann-Christine
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Sandström, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov G. W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Narvesjö, Jimmy
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Characterization of pyrolysis products produced from different Nordic biomass types in a cyclone pilot plant2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 146, p. 9-19Article in journal (Refereed)
    Abstract [en]

    Pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals and/or fuels. The objective of the present paper was to characterize fast pyrolysis products and to study pyrolysis oil fractionation. The products were obtained from different Nordic forest and agricultural feedstocks in a pilot scale cyclone pyrolysis plant at three different reactor temperatures. The results show that the main elements (C, H and O) and chemical compositions of the products produced from stem wood, willow, forest residue and reed canary grass are in general terms rather similar, while the products obtained from bark differ to some extent. The oil produced from bark had a higher H/Ceff ratio and heating value which can be correlated to a higher amount of pyrolytic lignin and extractives when compared with oils produced from the other feedstocks. Regardless of the original feedstock, the composition of the different pyrolysis oil fractions (condensed and aerosol) differs significantly from each other. However this opens up the possibility to use specifically selected fractions in targeted applications. An increased reactor temperature generally results in a higher amount of water and water insoluble material, primarily as small lignin derived oligomers, in the produced oil.

  • 7.
    Jones, Frida
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Ryde, Daniel
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Hjörnhede, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Down-time corrosion in boilers2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 141, p. 276-284Article in journal (Refereed)
    Abstract [en]

    Down-time corrosion can occur on boiler surfaces, e.g. furnace walls, superheaters, or economizers that are covered with hygroscopic deposits, when the temperature drops under 100 °C. This scenario takes place when a boiler is shut-down for cleaning, maintenance, or other reasons, such as unplanned shut-downs. Initially, the dry deposits will absorb moisture from the surrounding air, potentially creating a corrosive environment. After this, corrosive acids can form in the deposits. In this study modified online-corrosion probes were used in combination with deposits taken from 6 different boilers at various locations (for example, from the furnace, the superheater, and the economizer), where the fuels have been waste, demolition wood or biomass. The deposits were ground and dried in an oven at 160 °C for several hours before exposed to a moist environment (RH 65%) during online measuring of the corrosion rate and the pitting activity. Four types of alloys were tested: low-alloy ST45.8-steel, 9% Cr ferritic P91-steel, austenitic stainless steel 304L, and Ni-based super Alloy 625. The results for ST45.8 show that in biomass boilers a corrosion rate from negligible values up to 0.7 mm/year can be reached within a week, while waste-fired boilers can have rates as high as 1.8 mm/year. Furthermore, for some samples from waste-fired boilers show a high pitting activity already after 24 h. The tests with the P91-steel show values up to 0.16 mm/year, for samples from different locations in the boiler. For 304L and Alloy 625 the down-time corrosion was negligible even after a two-week exposure. The ability to follow the down-time corrosion online has provided data that show that even though thought to be negligible, the risk of down-time corrosion is of significance, especially if the fuel is waste. Also, even if the initial corrosion rate is low, it increases during the first 24 h due to the exposure to moist environment, motivating immediate cleaning of the boilers after shut-down, especially on surfaces of lower steel quality.

  • 8.
    Lundberg, Louise
    et al.
    Chalmers University of Technology, Sweden.
    Tchoffor, Placid A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Pallarès, 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.

  • 9.
    Moghaddam, Elham Ahmadi
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Ahlgren, Serina
    SLU Swedish University of Agricultural Sciences, Sweden.
    Hulteberg, Christian
    Lund University, Sweden.
    Nordberg, Åke
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik. SLU Swedish University of Agricultural Sciences, Sweden.
    Energy balance and global warming potential of biogas-based fuels from a life cycle perspective2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 132, p. 74-82Article in journal (Refereed)
    Abstract [en]

    Biogas is a multifunctional energy carrier currently used for co-generation or compressed biomethane as vehicle fuel. Gas-to-liquid (GTL) technology enables conversion of biogas into other energy carriers with higher energy density, facilitating fuel distribution.

    The energy efficiency and global warming potential (GWP) for conversion of biogas to compressed biogas (CBG), liquefied biogas (LBG), Fischer–Tropsch diesel (FTD), methanol and dimethyl ether (DME) were studied in a life cycle perspective covering the technical system from raw biogas to use in city buses.

    CBG, methanol and DME showed the best specific fuel productivity. However, when fuel distribution distances were longer, DME, LBG and methanol showed the best energy balance. Methanol, FTD and DME emitted half the GWP of LBG and CBG. Choice of electricity mix had a large impact on GWP performance. Overall, taking into account the different impact categories, combustion properties and fuel yield from raw biogas, DME showed the best performance of the fuel conversion scenarios assessed.

  • 10.
    Moradian, Farzad
    et al.
    University of Borås, Sweden.
    Tchoffor, Placid A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut. Chalmers University of Technology, Sweden.
    Davidsson, Kent O.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Pettersson, Anita
    University of Borås, Sweden.
    Backman, Rainer
    Umeå University, Sweden.
    Thermodynamic equilibrium prediction of bed agglomeration tendency in dual fluidized-bed gasification of forest residues2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 154, p. 82-90Article in journal (Refereed)
    Abstract [en]

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

  • 11.
    Niklasson, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Reduced bed temperature in a commercial waste to energy boiler - Impact on ash and deposit formation2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, no Jan, p. 28-36Article in journal (Refereed)
  • 12. Nordgren, D.
    et al.
    Hedman, H.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Padban, N.
    Bodstrom, D.
    Ohman, M.
    Ash transformations in pulverised fuel co-combustion of straw and woody biomass2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, p. 52-58Article in journal (Refereed)
    Abstract [en]

    Ash transformation processes have been studied during co-firing of wheat straw and pine stem wood and softwood bark. Pilot-scale trials in a 150kW pulverised-fuel-fired burner were performed. Thermodynamic equilibrium calculations were made to support the interpretation of the results. The results show that reactions involving condensed phases are kinetically limited compared to reactions between gaseous ash compounds. Accordingly, the conditions promote gas phase reactions resulting in the formation of chlorides, sulphates and carbonates whereas reactions involving condensed reactants are suppressed. Both the slagging and fouling propensities of all co-firing mixes were reduced compared to that for pure straw. For the wood/straw mixes this was mainly due to a dilution of the ash forming elements of straw whereas for straw/bark, an additional effect from interaction between the fuel ash components was observed to reduce slagging. In general it can be concluded that under powder combustion conditions equilibrium is approached selectively and that the ash matter is strongly fractionated. The general results in this paper are useful for straw-fired power stations looking for alternative co-firing fuels.

  • 13.
    Nordgren, D.
    et al.
    RISE, Innventia.
    Hedman, H.
    Padban, N.
    Boström, D.
    Öhman, M.
    Ash transformations in pulverised fuel co-combustion of straw and woody biomass2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, p. 52-58Article in journal (Refereed)
  • 14.
    Sandström, Linda
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Johansson, Ann-Christine
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Öhrman, Olov G. W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Marklund, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pyrolysis of Nordic biomass types in a cyclone pilot plant — Mass balances and yields2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 152, p. 274-284Article in journal (Refereed)
    Abstract [en]

    Fast pyrolysis of biomass results in a renewable product usually denoted pyrolysis oil or bio-oil, which has been suggested to be used as a direct substitute for fuel oil or as a feedstock for production of transportation fuels and/or chemicals. In the present work, fast pyrolysis of stem wood (originated from pine and spruce), willow, reed canary grass, brown forest residue and bark has been performed in a pilot scale cyclone reactor. The experiments were based on a biomass feeding rate of 20 kg/h at three different reactor temperatures. At the reference condition, pyrolysis of stem wood, willow, reed canary grass, and forest residue resulted in organic liquid yields in the range of 41 to 45% w/w, while pyrolysis of bark resulted in lower organic liquid yields. Two fractions of pyrolysis oil were obtained, denoted as the condensed and the aerosol fraction. Most of the water soluble molecules were collected in the condensed fraction, whereas the yield of water insoluble, heavy lignin molecules was higher in the aerosol fraction. Based on the results of the present work, willow, reed canary grass and forest residue are considered as promising raw materials for production of pyrolysis oil in a cyclone reactor.

  • 15.
    Sefidari, H.
    et al.
    Luleå University of Technology, Sweden; LKAB, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Lindblom, B.
    Luleå University of Technology, Sweden; LKAB, Sweden.
    Nordin, L. O.
    LKAB, Sweden.
    Wu, G.
    GTT Technologies, Germany; Institute of Energy and Climate Research, Germany.
    Yazhenskikh, E.
    Institute of Energy and Climate Research, Germany.
    Müller, M.
    Institute of Energy and Climate Research, Germany.
    Ma, C.
    Umeå University, Sweden.
    Öhman, M.
    Luleå University of Technology, Sweden.
    Comparison of high-rank coals with respect to slagging/deposition tendency at the transfer-chute of iron-ore pelletizing grate-kiln plants: A pilot-scale experimental study accompanied by thermochemical equilibrium modeling and viscosity estimations2019In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 193, p. 244-262Article in journal (Refereed)
    Abstract [en]

    Iron-ore pelletizing plants use high-rank coals to supply the heat necessary to process ores. Ash material from coal, in combination with iron-ore dust originating from the disintegration of the pellets, can cause deposition/slagging which often leads to severe production losses and damage. Deposition/slagging is most prominent in the hot areas of the grate-kiln setup and is more severe at the inlet of the rotary-kiln, i.e., the transfer-chute. Following on from our previous work, high-rank bituminous coals with potential for use in the pelletizing process were combusted in a pilot-scale (0.4 MW) pulverized-coal fired experimental combustion furnace (ECF). The fly-ash particles and short-term deposits were characterized to shed light on the observed difference in slagging/deposition tendencies of the coals. Global thermodynamic equilibrium modeling, in combination with viscosity estimates, was used to interpret the experimental findings and investigate the effect of the coal-ash composition upon deposition/slagging. This approach was carried out with and without the presence of Fe2O3-rich pellet-dust under oxidizing conditions within the temperature range at the transfer-chute of iron-ore pelletizing rotary-kilns. Based on the findings, a Qualitative Slagging Indicator (QSI) was proposed that can help pre-screen new solid fuels for potential slagging issues. The proposed QSI highlights the following: (1) an inverse relationship between viscosity and slagging/deposition tendency of the coals was observed (2) as viscosity decreases (either with increasing temperature or due to the change in the coal-ash composition), stronger deposits will form that will complicate the mechanical removal of the deposited layer. It was therefore inferred that low viscosity molten phases facilitate deposition/slagging, which is exacerbated by the presence of fluxing agents (e.g., CaO, MgO, K2O, Na2O, and Fe2O3) in the deposits. The low viscosity coal-ash-induced molten phases are also more likely to interact with the Fe2O3-rich pellet-dust that results in further decreases in viscosity, thereby intensifying depositions. The results from this work complement the on-going research by our group to elucidate and alleviate ash-related problems in industrial grate kilns.

  • 16.
    Sefidari, Hamid
    et al.
    Luleå University of Technology, Sweden.
    Lindblom, Bo
    Luleå University of Technology, Sweden ; LKAB, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Nordin, Lars Olof
    LKAB, Sweden.
    Lennartsson, Andreas
    Luleå University of Technology, Sweden.
    Mouzon, Johanne
    Luleå University of Technology, Sweden.
    Bhuiyan, Iftehkar
    Luleå University of Technology, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Sweden.
    The effect of disintegrated iron-ore pellet dust on deposit formation in a pilot-scale pulverized coal combustion furnace. Part II: Thermochemical equilibrium calculations and viscosity estimations2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 180, p. 189-206Article in journal (Refereed)
    Abstract [en]

    Fly ash particles from the combustion of solid-fuels together with disintegrated particles arising from iron-ore pellets result in accumulation of deposits on the refractory linings of the grate-kiln induration machine during the iron-ore pelletizing process. The deposits amass in the high-temperature regions of the induration furnace thus disturbing the flow of gas and pellets. Therefore, to tackle the above-mentioned issues, an understanding of deposit formation mechanism is of crucial importance. This study was conducted with the objective of addressing the effect of disintegrated iron-ore pellet dust on deposit formation and the mechanisms behind deposition (slagging) in the grate-kiln process. A comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal- fired furnace where three different scenarios were considered as follows; Case 1 (reference case): Coal was combusted without the presence of pellet dust. Case 2: Natural gas was combusted together with simultaneous addition of pellet dust to the gas stream. Case 3: Coal was combusted together with the addition of pellet dust simulating the situation in the large-scale setup. Fly ash particles and short-term deposits were characterized and deposition was addressed in Part I of this study. In light of the experimental observations (Part I) and the thermochemical equilibrium calculations (Part II), a scheme of ash transformation during the iron-ore pelletizing process was proposed. The dissolution of hematite particles into the Ca-rich-aluminosilicate melt (from the coal-ash constituents) decreased the viscosity and resulted in the formation of stronger (heavily sintered) deposits. Overall, this pilot-scale work forms part of a wider study which aims at deepening the understanding of ash transformation phenomena during the large-scale pelletizing process.

  • 17.
    Sefidari, Hamid
    et al.
    Luleå University of Technology, Sweden.
    Lindblom, Bo
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Nordin, Lars-Olof
    LKAB, Sweden.
    Mouzon, Johanna
    Luleå University of Technology, Sweden.
    Bhuiyan, Iftekhar Uddin
    Luleå University of Technology, Sweden.
    Öhman, Marcus
    Luleå University of Technology, Sweden.
    The effect of disintegrated iron-ore pellet dust on deposit formation in a pilot-scale pulverized coal combustion furnace. Part I: Characterization of process gas particles and deposits2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 177, p. 283-298Article in journal (Refereed)
    Abstract [en]

    To initiate the elucidation of deposit formation during the iron-ore pelletization process, a comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal-fired furnace where three different scenarios were considered as follows; Case 1 (reference case): Coal was combusted without the presence of pellet dust. Case 2: Natural gas was combusted together with simultaneous addition of pellet dust to the gas stream. Case 3: Coal was combusted together with the addition of pellet dust simulating the situation in the large-scale grate-kiln setup. Particles and deposits were sampled from 3 positions of different temperature via a water-cooled sampling probe. Three distinct fragmentation modes were identified based on the aerodynamic particle diameter (Dp). The fine mode: Particles with 0.03 < Dp < 0.06 μm. The first fragmentation mode: Particles with 1 < Dp < 10 μm. The second fragmentation mode: Coarse particles (cyclone particles, Dp > 10 μm). A transition from a bimodal PSD (particle size distribution) to a trimodal PSD was observed when pellet dust was added (Case 3) and consequently the elemental bulk composition of the abovementioned modes was changed. The most extensive interaction between pellet dust and coal-ash particles was observed in the coarse mode where a significant number of coal ash globules were found attached to the surface of the hematite particles. The morphology of the sharp-edged hematite particles was changed to smooth-edged round particles which proved that hematite particles must have interacted with the surrounding aluminosilicate glassy phase originating from the coal ash. The short-term deposits collected during coal combustion (Case 1) were highly porous in contrast to the high degree of sintering observed in the experiments with pellet dust addition (Case 3) which is attributed to the dissolution of hematite particles in the aluminosilicate glassy phase. The results suggest that pellet dust itself (Case 2) has low slagging tendency, independent of temperature. However, when coal-ash is present (Case 3), auxiliary phases are added such that tenacious particles are formed and slagging occurs.

  • 18.
    Sette, Erik
    et al.
    Chalmers University of Technology, Sweden.
    Pallars, David
    Chalmers University of Technology, Sweden.
    Johnsson, Filip
    Chalmers University of Technology, Sweden.
    Ahrentorp, Fredrik
    RISE, Swedish ICT, Acreo.
    Ericsson, Anders
    RISE, Swedish ICT, Acreo.
    Johansson, Christer
    RISE, Swedish ICT, Acreo.
    Magnetic tracer-particle tracking in a fluid dynamically down-scaled bubbling fluidized bed2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, p. 368-377Article in journal (Refereed)
    Abstract [en]

    A method for 3-dimensional (3D) magnetic tracer particle tracking in a fluid dynamically downscaled fluidized bed is presented. The method applies anisotropic magnetoresistive (AMR) sensors to track a magnetic tracer particle in the form of an NdFeB-based permanent magnet. The fluid dynamically downscaled bed has a cross-section of 0.17 × 0.17 m2and is operated at ambient conditions with bronze powder as bulk solids and the tracer particle corresponding to a fuel particle. After up-scaling the bed corresponds to a 0.85 × 0.85 m2 bed of fuel ash or silica sand operated with air at 900 °C using anthracite coal as a fuel. Thus, the method provides continuous tracking of the tracer particle trajectorywhich, combined with the fluid dynamic scaling yields quantitativeinformation applicable to the study of fuel mixing in large-scale fluidized-bed processes operating under hot conditions. Application of the method represents a significant step forward compared to other experimental studies which are limited to qualitative interpretations; performed in 2D units and in cold 3D units which are not fluid dynamically scaled.

    It is shown that the AMR sensor system is able to work with the (non-magnetic) bronze powder resulting from the fluid dynamical downscaling, i.e. overcoming the limitation in signal penetration which prevents tracking of radioactive objects in such dense media. Thus, successful application of the AMR method for continuous 3D object tracking in a fluid dynamically downscaled unit is demonstrated for the first time. The measurement system provides both translational and rotational data, unleashing possibilities also as a validation tool of CFD models. The preliminary results show a spatial resolution on the order of 1 mm, while temporal resolution is on the order of milliseconds.

  • 19.
    Weiland, Fredrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordwaeger, M.
    Olofsson, I.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nordin, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Entrained flow gasification of torrefied wood residues2014In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 125, p. 51-58Article in journal (Refereed)
    Abstract [en]

    In this work, four different fuels were gasified in a pressurized entrained flow pilot plant gasifier at approximately 270 kWth. The different fuels were; two torrefied wood residues, one raw wood residue and one torrefied stem wood. The system pressure and oxygen equivalence ratio (λ) were held constant for all four gasification experiments. It was found that the torrefaction pretreatment significantly reduced the milling energy consumption for fuel size reduction, which in turn contributed to increased gasification plant efficiency. Furthermore, the results indicate that the carbon conversion efficiency may be enhanced by an intermediate torrefaction pretreatment, whereas both less severe torrefaction and more severe torrefaction resulted in reduced carbon conversions. The results also indicate that the CH4 yield was significantly reduced for the most severely torrefied fuel. © 2014 Elsevier B.V. All rights reserved.

  • 20.
    Ögren, Yngve
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Gullberg, Marcus
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wennebro, Jonas
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Toth, Pal
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Influence of oxidizer injection angle on the entrained flow gasification of torrefied wood powder2018In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 181, p. 8-17Article in journal (Refereed)
    Abstract [en]

    In the present work, 5 different axisymmetric burners with different directions of the oxidizer inlets were experimentally tested during oxygen blown gasification of torrefied wood powder. The burners were evaluated under two different O2/fuel ratios at a thermal power of 135 kWth, based on the heating value of torrefied wood powder. The evaluation was based on both conventional methods such as gas chromatography measurements and thermocouples and in-situ measurements using Tunable Diode Laser Absorption Spectroscopy. It was shown that changes in the near burner region influence the process efficiency significantly. Changing the injection angle of the oxidizer stream to form a converging oxidizer jet increased process efficiency by 20%. Besides increased process efficiency, it was shown that improvements in burner design also influence carbon conversion and hydrocarbon production. The burner with the best performance also produced less CH4 and achieved the highest carbon conversion. The effect of generating swirl via rotating the oxidizer jet axes was also investigated. Swirl broadened or removed the impingement area between the fuel and oxidizer jets, however resulting in differences in performance within the measurement uncertainty.

  • 21.
    Öhrman, Olov .G.W
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Weiland, Fredrik
    Pettersson, E.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Johansson, Ann-Christine
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedman, Henry
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pedersen, M.
    Pressurized oxygen blown entrained flow gasification of a biorefinery lignin residue2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 115, p. 130-138Article in journal (Refereed)
    Abstract [en]

    Renewable fuels could in the future be produced in a biorefinery which involves highly integrated technologies. It has been reported that thermochemical conversion (gasification) of lignocellulosic biomass has a high potential for end production of renewable biofuels. In this work, lignin residue from biochemical conversion of wheat straw was gasified in an oxygen blown pressurized entrained flow gasifier (PEBG) at 0.25-0.30 MWth, 0.45 < λ < 0.5 and 1 bar (g). A video camera mounted inside the PEBG was used to observe the flame during start up and during operation. Hydrogen (H 2), carbon monoxide (CO) and carbon dioxide (CO2) were the main gas components with H2/CO ratios varying during the gasification test (0.54-0.63). The methane (CH4) concentration also varied slightly and was generally below 1.7% (dry and N2 free). C2-hydrocarbons (< 1810 ppm) and benzene (< 680 ppm) were also observed together with low concentrations of hydrogen sulfide (H2S, < 352 ppm) and carbonyl sulfide (COS, < 131 ppm). The process temperature in the reactor was around 1200 C. The slag seemed to consist of Cristobalite (SiO2) and Berlinite (AlPO4) and Na, Ca, Mg, K and Fe in lower concentrations. Cooling of the burner will be necessary for longer tests to avoid safety shut downs due to high burner temperature. The cold gas efficiency and carbon conversion was estimated but more accurate measurements, especially the syngas flow, needs to be determined during a longer test in order to obtain data on the efficiency at optimized operating conditions. The syngas has potential for further upgrading into biofuels, but will need traditional gas cleaning such as acid gas removal and water gas shifting. Also, higher pressures and reducing the amount of N2 is important in further work. © 2013 Elsevier B.V.

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