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  • 1.
    Alevanau, Aliaksandr
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Ahmed, Islam
    Gupta, Ashwani K.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Parameters of high temperature steam gasification of original and pulverised wood pellets2011Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, nr 10, s. 2068-2074Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experiments on gasification of chars obtained from original and pulverised wood pellets were conducted in atmosphere of water steam and nitrogen under temperatures of 800, 900 and 950 degrees C. Molar flow rates of carbon containing product gases were measured and approximated using different models with respect to extents of carbon conversion in char of the pellets. Comparison of the random pore, grain and volumetric models revealed the best applicability for approximations of the random pore model. Apparent activation energies obtained as a result of application of the models to the data from experiments with char of original pellets were higher in comparison to those of pulverised pellets, except for a grain model. Approximations under 800 degrees C showed relatively big deviations from experimental data on the beginning of char gasification. This is attributed to catalytic effects from alkali metals in the pellets.

  • 2.
    Alevanau, Aliaksandr
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Kantarelis, Efthymios
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis2013Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 106, s. 253-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurements of temperature in the proximity of wood pellets (8 mm diameter) and thin wooden stick slices (5 cm diameter and 5 mm thickness) were conducted to estimate the effects of mixing between the evolving volatiles and hot steam (T > 700°C) flowing around the particles. Measurements of mass loss of the slices were conducted to estimate the apparent kinetic parameters of their pyrolysis. A simple kinetic model of the process (type II by Pyle and Zaror (1984) [20]) was investigated. The experiments showed a plateau-like part in the graphs of temperature measured in the proximity to the samples. The existence of this plateau-like part agrees with the general data of calorimetric measurements of pyrolysis, which show extensive energy consumption in the beginning of an active production of volatiles. A hypothesis regarding feedback on the process due to the micro-expansion and mixing of volatiles in the convective boundary layer is discussed.

  • 3.
    Alipour, Yousef
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Talus, A.
    Henderson, Pamela
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. Vattenfall AB, Stockholm 169 92, Sweden.
    Norling, R.
    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 region2015Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, s. 805-813Artikel i tidskrift (Refereegranskat)
    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.

  • 4.
    Biswas, Amit Kumar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Umeki, Kentaro
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Change of pyrolysis characteristics and structure of woody biomass due to steam explosion pretreatment2011Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, nr 10, s. 1849-1854Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Steam explosion (SE) pretreatment has been implemented for the production of wood pellet. This paper investigated changes in biomass structure due to implication of steam explosion process by its pyrolysis behavior/characteristics. Salix wood chip was treated by SE at different pretreatment conditions, and then pyrolysis characteristic was examined by thermogravimetric analyzer (TGA) at heating rate of 10 K/min. Both pyrolysis characteristics and structure of biomass were altered due to SE pretreatment. Hemicellulose decomposition region shifted to low temperature range due to the depolymerization caused by SE pretreatment. The peak intensities of cellulose decreased at mild pretreatment condition while they increased at severe conditions. Lignin reactivity also increased due to SE pretreatment. However, severe pretreatment condition resulted in reduction of lignin reactivity due to condensation and re-polymerization reaction. In summary, higher pretreatment temperature provided more active biomass compared with milder pretreatment conditions.

  • 5.
    Biswas, Amit Kumar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Devolatilization characteristics of steam explosion pretreated wood pelletIngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188Artikel i tidskrift (Övrigt vetenskapligt)
  • 6.
    Biswas, Amit Kumar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Steam pretreatment of Salix to upgrade biomass fuel for wood pellet production2011Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, nr 9, s. 1711-1717Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Steam explosion (SE) pretreatment is served to separate the main components of woody biomass. In general there is a noticeable gap in literature in terms of application of steam explosion process to upgrade biomass fuel for wood pellet production. In order to study the influence of steam explosion pretreatment on biomass fuel, Salix wood chips was used as raw material. Four different SE experiments were performed by varying two key process factors; time and temperature. Elementary quality and ash properties of the pretreated residue were investigated. Moreover, physical and thermochemical properties of the pellet, produced from the residue, were also investigated. Reduction in ash content especially in alkali metals was observed in steam treated residue. Pretreatment of biomass also enhanced carbon content and reduced oxygen amount in the fuel which enhanced the heating value of the fuel. Moreover, pretreatment enhanced pellet density, impact resistance, and abrasive resistance of pellet. However, small degradation in ash fusion characteristics and char reactivity was also observed as the severity of the process increased.

  • 7. Budinova, T.
    et al.
    Ekinci, E.
    Yardim, F.
    Grimm, Alejandro
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Björnbom, Emilia
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Minkova, V.
    Goranova, M.
    Characterization and application of activated carbon produced by H3PO4 and water vapor activation2006Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 87, nr 10, s. 899-905Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Activated carbons have been prepared from woody biomass birch by using various activation procedures: a) treatment with phosphoric acid and pyrolysis at 600 degrees C in inert atmosphere, b) the same as in (a) followed by steam activation at the same temperature and c) treatment with phosphoric acid and direct pyrolysis in a stream of water vapor at 700 degrees C. The surface area and the porosity of the activated carbons were strongly dependent on the treatment after impregnation with H3PO4 (pyrolysis in inert atmosphere, steam pyrolysis or combination of both). Activated carbon, prepared by impregnation with phosphoric acid followed by steam pyrolysis (steam activation) had highly developed porous structure and the largest surface area among all prepared carbons (iodine number 1280 mg/g and BET surface area 1360 m(2)/g). The adsorption capacity of this sample for Hg(II) from aqueous solution was studied in varying treatment conditions: contact time, metal ion concentration and pH. The adsorption followed Langmuir isotherms and the adsorption capacity for Hg(II) at 293 K was 160 mg/g.

  • 8.
    Minkova, V.
    et al.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Marinov, S. P.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Zanzi, Rolando
    KTH, Tidigare Institutioner, Kemiteknik. KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Bjornbom, E.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Budinova, T.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Stefanova, M.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Lakov, L.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Thermochemical treatment of biomass in a flow of steam or in a mixture of steam and carbon dioxide2000Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 62, nr 1, s. 45-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simultaneous pyrolysis and gasification of biomass samples of different origin is performed in a flow of steam or in a mixture of steam and carbon dioxide. Wastes from birch wood, olive stones, bagasse, and pellets from straw and Miscanthus are used as feedstock. The raw materials are heated with 10 degrees C/min to 750 degrees C at atmospheric pressure and kept for a period of 2 h at this temperature, Laboratory experimental equipment with a horizontal rotating stainless steel reactor is used. The oxygen-containing functional groups in the solid products (-COOH, =CO and -OH) are determined using the method of Boehm. The results are compared with those obtained in treatment in inert atmosphere as well as with those obtained in a stationary reactor. The rotating pyrolysis reactor seems suitable for production of energy-rich gaseous products and activated carbons.

  • 9.
    Minkova, V.
    et al.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Razvigorova, M.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Bjornbom, E.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk reaktionsteknik.
    Zanzi, Rolando
    KTH, Tidigare Institutioner, Kemiteknik. KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Budinova, T.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Petrov, N.
    Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia .
    Effect of water vapour and biomass nature on the yield and quality of the pyrolysis products from biomass2001Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 70, nr 1, s. 53-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Slow pyrolysis/activation of biomass in a flow of steam is studied in laboratory equipment supplied with a fixed bed reactor. Forestry and agricultural residues of different origin are selected as raw materials (birch wood, olive stones, bagasse, pelletised straw and miscanthus). The final pyrolysis temperature is varied in the range 700-800 degreesC and the duration of the activation is 1 or 2 h. The effect of both the nature of the investigated biomass samples and the presence of water vapour on the quality of the pyrolysis products is in the focus of interest of this work. Column chromatography is used to characterize the liquid products. The surface area and the acid-base neutralization capacity of the solid products are determined by the adsorption capacity towards iodine and reactions with EtONa and HCl. The results are compared with those obtained in pyrolysis in inert atmosphere of nitrogen. It is shown that the presence of steam has strong effect on the yield and properties of the products. Significant part of the liquid product is found dissolved in the water phase obtained after condensation of the volatiles. The solid products obtained in the presence of steam have the properties of activated carbons.

  • 10.
    Nylén, Ulf
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Frontela Delgado, Juana
    Järås, Sven
    KTH, Tidigare Institutioner, Kemiteknik.
    Boutonnet, Magali
    KTH, Tidigare Institutioner, Kemiteknik.
    Characterization of alkylated aromatic sulphur compounds in light cycle oil from hydrotreated vacuum gas oil using GC-SCD2004Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 86, nr 2, s. 223-234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A light cycle oil (LCO) fraction in the boiling point range 220-337 degreesC was successfully characterized in detail with respect to 29 individual aromatic sulphur compounds and total sulphur content using high-resolution gas chromatography with sulphur chemiluminescence detection (HRGC-SCD). The resulting chromatogram, although very complex with hundreds of different alkyl-substituted aromatic sulphur derivatives, was well resolved owing to the high performance Equity-1 column and the optimised GC method. A shift in the sulphur distribution towards the heavier homologues was observed due to the origin of the LCO, derived from hydrotreated vacuum gas oil.

  • 11.
    Ponzio, Anna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Kalisz, Sylwester
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzmierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Effect of operating conditions on tar and gas composition in high temperature air/steam gasification (HTAG) of plastic containing waste2006Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 87, nr 3, s. 223-233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the high temperature air/steam gasification (HTAG) technique has been tested for a fuel in pellet form made from waste material of woody and plastic origin. The feedstock was gasified in an updraft fixed bed reactor by mixtures of air and steam (102 Nm(3)/h, 4% to 82% steam) preheated to 1400 degrees C, a temperature well above the fluid temperature of the feedstock. The produced gas was analyzed with respect to composition, including a detailed characterization of the tar. Lower heating values up to 9.5 MJ/Nm(3) and gas yields as high as 3.4 Nm(3)/kg were reported, indicating the process to be highly efficient for waste-to-energy applications. The composition of the tars, suggested extensive cracking as a result of the high temperatures of the outgoing gas.

  • 12.
    Samuelsson, Lina N.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Bäbler, Matthäus U.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Brännvall, Elisabet
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Moriana, Rosana
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Pyrolysis of kraft pulp and black liquor precipitates derived from spruce: Thermal and kinetic analysis2016Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 149, s. 275-284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The potential of seven kraft cook materials to become functional char materials and fuels is investigated. Thermogravimetric analysis was used to study the thermal properties while a model-free isoconversional method was used to derive kinetic rate expressions. Black liquor precipitates had lower thermal stability (20-60 K lower) than pulps and spruce wood and the precipitates decomposed in a wider temperature range, producing chars with similar or higher thermal stability than char from pulps, but lower than those from spruce wood. Samples suitable to produce char were identified based on char yield, devolatilization rate and charring temperature. The highest char yield (46%), achieved from a precipitate, was more than twice as high as that from spruce powder. Under the studied conditions none of the materials had a pyrolysis process that for the whole conversion range could be described with a single set of kinetic parameters. The apparent activation energy varied between 170-260 kJ/mol for the pulps and 50-650 kJ/mol for the precipitates. The derived kinetic parameters were validated by predicting the conversion at a heating rate outside the range used for its derivation and at quasi isothermal conditions. Both these tests gave satisfactory results in good agreement with experimental data.

  • 13.
    Samuelsson, Lina N.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Umeki, K.
    Bäbler, Matthäus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Mass loss rates for wood chips at isothermal pyrolysis conditions: A comparison with low heating rate powder data2017Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 158, s. 26-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spruce chips of three different thicknesses were pyrolyzed isothermally in a vertical furnace macro-TGA at 574 to 676K, which is the temperature range relevant for char production. The measured mass loss data was analyzed in terms of mass loss rate, thermal lag and char yield as a function of chip size and pyrolysis temperature. The char yield decreased with increasing temperature and there was no significant difference in char yield as a function of sample thickness, ranging from 1mm to 7mm. Thermal lag was present for all chip sizes above 600K. At 574K the data suggests that chips below 1mm in thickness are decomposing at rates governed by reaction kinetics. An isoconversional kinetic model based on low heating rate data of spruce powder was adopted to analyze the data. The model predicted lower mass loss rates than those measured for the chips, suggesting that the pyrolysis process of wood proceeds through a network of parallel reactions. Despite this, the model could predict the final char yield of the wood chips with an accuracy above 80%. The predictive capability of the isoconversional reaction rate expression is promising since the procedure to derive such a rate expression is straight-forward, compared to the conventional model-fitting methods. The data and modeling approach presented in this work is important to the field of biomass pyrolysis as it covers the temperature range and chip sizes relevant for pyrolysis in multi-staged gasification plants which has been given little attention.

  • 14.
    Tristantini, Dewi
    et al.
    Chalmers Tekniska Högskola.
    Lögdberg, Sara
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Gevert, Börje
    Chalmers Tekniska Högskola.
    Borg, Öjvind
    Norwegian University of Science and Technology.
    Holmen, Anders
    Norwegian University of Science and Technology.
    The effect of synthesis gas composition on the Fischer-Tropsch synthesis over Co/Al2O3 and Co-Re/ γ-Al2O3 catalysts2007Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 88, nr 7, s. 643-649Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Fischer-Tropsch synthesis over Co/gamma-Al2O3 and Co-Re/gamma-Al2O3 was investigated in a fixed-bed reactor at 20 bar and 483K using feed gases with molar H-2/CO ratios of 2.1, 1.5 and 1.0 simulating synthesis gas derived from biomass. With lower H-2/CO ratios in the feed, the CO conversion and the CH4 selectivity decreased, while the C5+ selectivity and olefin/paraffin ratio for C-2-C-4 increased slightly. The water-gas shift activity was low for both catalysts, resulting in high molar usage ratios of H-2/CO (close to 2.0), even at the lower inlet ratios (i.e. 1.5 and 1.0). For both catalysts, the drop in the production rate of hydrocarbons when shifting from an inlet ratio of 2.1 to 1.5 was significant mainly because the H-2/CO usage ratio did not follow the change in the inlet ratio. The hydrocarbon selectivities were rather similar for inlet H-2/CO ratios of 2.1 and 1.5, while significantly deviating from those for an inlet ratio of 1.0. With the studied catalysts, it is possible to utilize the advantages of an inlet ratio of 1.0 (higher selectivity to C5+, lower selectivity to CH4, no water-gas shifting of the bio-syngas needed prior to the FT reactor) if a low syngas conversion is accepted.

  • 15.
    Tsamba, Alberto Júlio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Pyrolysis characteristics and global kinetics of coconut and cashew nut shells2006Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 87, nr 6, s. 523-530Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coconut and cashew nut shells are two typical biomass wastes abundant in most of the tropical countries. However, despite their enormous potential as energy sources, they are hardly studied and their thermal characteristics are still not well known. In this study, both biomasses are thermally degraded through thermogravimetry and their characteristics such as devolatilisation profiles and kinetics are analyzed, from 250 to 900 °C, in an inert atmosphere, at two different heating rates, and compared with wood pellets. The results show that their pyrolysis profiles are different from that of the commonly studied woody biomass. In fact, they present two different peaks instead of the one overlapping peak, for hemicellulose and cellulose. In addition, they present activation energies ranging from that are slightly above the commonly known maximum for biomass. At 10 and 20 °C/min the activation energy varied from about 130 to 174 and 180 to 216 kJ/mol, for cashew and coconut shells, respectively.

  • 16.
    Viklund, Peter
    et al.
    Swerea KIMAB AB, Stockholm, Sweden.
    Hjörnhede, Anders
    Vattenfall Power Consultants AB, Göteborg, Sweden.
    Henderson, Pamela
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Stålenheim, Annika
    Vattenfall Research and Development AB, Stockholm, Sweden.
    Pettersson, Rachel
    Outokumpu Stainless AB, Avesta, Swden.
    Corrosion of superheater materials in a waste-to-energy plant2013Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 105, nr SI, s. 106-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major drawback when generating electricity from waste-fired boilers is the rapid corrosion of critical components such as superheater tubes. In this work a number of commonly-used superheater materials have been exposed on internally cooled probes in a waste-fired grate boiler. The investigated materials are the ferritic steel 13CrMo44, the ferritic-martensitic steel HCM12A, the austenitic steels Super 304, 317L and Sanicro 28, and the nickel-base alloys Hastelloy C-2000 and Inconel 625. Short-term exposures (3 h) for analysis of deposit composition and initial corrosion, as well as long-term exposures (1550 h) to investigate corrosion rates and corrosion characteristics have been made. Analysis revealed a deposit dominated by CaSO4, KCl and NaCl, but also appreciable amounts of low melting salt mixtures such as ZnCl2-KCl, PbCl2-KCl, FeCl2-KCl and NaCl-NiCl2. Metal loss measurements showed unacceptably high corrosion rates for 13CrMo44, HCM12A and Super 304. The corrosion attack for these alloys was manifested by the formation of mixed metal chloride/metal oxide scales. A different type of behaviour was seen for the higher alloyed austenitic steels and nickel-base alloys, which were able to form a chromium-enriched oxide next to the metal. However, these alloys suffered from some localised pitting attack. The behaviour is explained by oxide dissolution in the molten salts that are present in the deposit.

  • 17.
    Wilson, Lugano
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    John, Geoffrey R.
    Mhilu, Cuthbert F.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Coffee husks gasification using high temperature air/steam agent2010Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 91, nr 10, s. 1330-1337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analyses made on the world's biomass energy potential show that biomass energy is the most abundant sustainable renewable energy. The available technical biomass energy potential surpasses the total world's consumption levels of petroleum oils, coal and natural gas. In order to achieve a sustainable harnessing of the biomass energy potential and to increase its contribution to the world's primary energy consumption, there is therefore a need to develop and sustain contemporary technologies that increase the biomass-to-energy conversion. One such technology is the high temperature air/steam gasification (HTAG) of biomass. In this paper we present findings of gasification experimental studies that were conducted using coffee husks under high temperature conditions. The experiments were performed using a batch facility, which was maintained at three different gasification temperatures of 900 °C, 800 °C, and 700 °C. The study findings exhibited the positive influence of high temperature on increasing the gasification process. Chars left while gasifying at 800 °C and 700 °C were respectively 1.5 and 2.4 times that for the case of 900 °C. Furthermore, increased gasification temperature led to a linear increment of CO concentration in the syngas for all gasification conditions. The effect was more pronounced for the generally poorly performing gasification conditions of N2 and 2% oxygen concentration. When gasification temperature was increased from 700 °C to 900 °C the CO yield for the 2% O2 concentration increased by 6 times and that of N2 condition by 2.5 times. The respective increment for the 3% and 4% O2 conditions were only twofold. This study estimated the kinetic parameters for the coffee husks thermal degradation that exhibited a reaction mechanism of zero order with apparent activation energy of 161 kJ/mol and frequency factor of 3.89 × 104/min.

  • 18.
    Yang, Weihong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, W.
    Mathematical modelling of NO emissions from high-temperature air combustion with nitrous oxide mechanism2005Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 86, nr 9, s. 943-957Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A study of the mathematical modelling of NO formation and emissions in a gas-fired regenerative furnace with high-preheated air was performed. The model of NO formation via N2O-intermediate mechanism was proposed because of the lower flame temperature in this case. The reaction rates of this new model were calculated basing on the eddy-dissipation-concept. This model accompanied with thermal-NO, prompt-NO and NO reburning models were used to predict NO emissions and formations. The sensitivity of the furnace temperature and the oxygen availability on NO generation rate has been investigated. The predicted results were compared with experimental values. The results show that NO emission formed by N2O-intermediate mechanism is of outstanding importance during the high-temperature air combustion (HiTAC) condition. Furthermore, it shows that NO models with N2O-route model can give more reasonable profile of NO formation. Additionally, increasing excess air ratio leads to increasing of NO emission in the regenerative furnace.

  • 19.
    Yang, Weihong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Ponzio, Anna
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Lucas, Carlos
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blaslak, Wlodzmierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Performance analysis of a fixed-bed biomass gasifier using high-temperature air2006Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 87, nr 3, s. 235-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gasification of biomass using high-temperature agents (air/steam) has been proven to have many features superior to those of conventional gasification using low-temperature agents. In this work, an experimental fixed-bed gasifier is utilized to investigate the gasification of biomass using high-temperature air up to 1473 K. A mathematical model has been formulated for the prediction of the main chemical and physical processes and is used to study the influence of temperature, oxygen concentration and flow rate of the feed gas. Predicted gas species concentration profiles and their maximum values are in reasonable agreements with the measurements. The results show that: (a) When the temperature of feed gas is increased, a higher gasification rate, a higher ignition front rate, and higher molar fractions of fuel gases (CO, H-2 and CmHn), thus a higher LHV are obtained. (b) Increased oxygen concentration leads to higher peak values of the fuel gas concentrations, a higher gasification rate, and a larger ignition front rate.

  • 20.
    Zhang, Qinglin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Dor, Liran
    Biswas, Amit
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Modeling of steam plasma gasification for municipal solid waste2013Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 106, s. 546-554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasma gasification melting (PGM) is a promising gasification technology aiming at providing sustainable disposal for various wastes. In this work, an Euler-Euler multiphase model was developed to study the characteristics of air and steam gasification of municipal solid waste in a PGM reactor. The model is validated by measurement data from a demonstration PGM reactor. With this model, three groups of simulations were performed to study the influences of operating conditions. It is confirmed that injection of high temperature steam is important for increasing the cold gas efficiency and syngas lower-heating-value. The effect of steam injection is affected by steam feeding rate, air feeding rate and plasma power. Based on the simulated results, an optimal condition is suggested for air and steam gasification in the PGM reactor.

  • 21.
    Zhou, Chunguang
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Rosén, Christer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Selection of dolomite bed material for pressurized biomass gasification in BFB2017Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 167, s. 511-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dolomite is considered advantageous as bed material in fluidized bed gasification processes, due to its catalytic tar cracking and anti-sintering properties. However, in case of pressurized fluidized bed gasifiers, the use of dolomite is challenging. High temperature in the presence of steam favors the production of clean syngas due to the intensified cracking of tar in the presence of CaO, whereas it simultaneously increases the tendency of fragmentation of dolomite particles after full calcination. The present study was carried out to examine the influence of the properties of dolomite on the stability of dolomite in a pressurized fluidized bed gasifier, with the aim of determining criteria for dolomite selection. Glanshanunar dolomite exhibited a better stability in the mechanical strength after calcination, compared to Sala dolomite. The corresponding change of micro-structure that occurred during dolomite chemical transformation was presented. The crystal pattern and Si distribution in the crystal lattice are the possible explanations for the superior performance of the Glanshammar dolomite compared to the Sala dolomite.

  • 22.
    Zhou, Chunguang
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rosén, Christer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Selection of dolomite bed material for pressurized biomass gasification in BFB2017Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 159, s. 460-473Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dolomite is considered advantageous as bed material in fluidized bed gasification processes, due to its catalytic tar cracking and anti-sintering properties. However, in case of pressurized fluidized bed gasifiers, the use of dolomite is challenging. High temperature in the presence of steam favors the production of clean syngas due to the intensified cracking of tar in the presence of CaO, whereas it simultaneously increases the tendency of fragmentation of dolomite particles after full calcination. The present study was carried out to examine the influence of the properties of dolomite on the stability of dolomite in a pressurized fluidized bed gasifier, with the aim of determining criteria for dolomite selection. Glanshammar dolomite exhibited a better stability in the mechanital strength after calcination, compared to Sala dolomite. The corresponding change of micro-structure that occurred during dolomite chemical transformation was presented. The crystal pattern and Si distribution in the crystal lattice are the possible explanations for the superior performance of the Glanshammar dolomite compared to the Sala dolomite.

  • 23.
    Zhou, Chunguang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Characteristics of waste printing paper and cardboard in a reactor pyrolyzed by preheated agents2013Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 116, s. 63-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We studied the characteristics of waste printing paper and cardboard particles in a reactor pyrolyzed by preheated agents with the aim of simulating a real case in a fixed-bed gasifier. A TGA/DSC was first used to study of the kinetics and enthalpy change of the printing paper and cardboard pyrolysis. Pyrolitic conversion was further carried out in a batch-type reactor with non-electrical heating. Syngas, tar and char were produced and characterized from printing paper and cardboard pyrolysis at 400 degrees C, 500 degrees C and 600 degrees C. Different flow rates of carrier gas were applied to study the effect of residence time on the products distribution. When the flow rate increased, the relative mass change of gas agrees with that of tar. With increase in temperature, the yield of furfural, olefins and other non-aromatic compounds in tar decreased, while phenols and heavier aromatic hydrocarbons increased. The evolution of CO2, CO and other gas species in the syngas was presented. Van Krevelan diagram of chars was also presented in the paper.

1 - 23 av 23
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