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  • 51.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Pitchot, Romain
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Andefors, Alf
    Future Eco North Sweden AB.
    Norberg, Niclas
    Future Eco North Sweden AB.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Production of metallurgical charcoal from biomass pyrolysis: pilot-scale experiment2018Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 52.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Change in size and density of a biomass char during heterogeneous reactions2018Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 53.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wretborn, Tobias
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Biomass pyrolysis with bio-oil recycle to increase energy recovery in biochar2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    ABSTRACT: This study aims at increasing char yield by recycling bio-oil without negative impact on char qualities, i.e. carbon content and heating value. Pyrolysis experiments on spruce and birch chips were carried in a macro-thermogravimetric analyzer. To examine the effect of bio-oil recycle, dried raw woodchips, pure bio-oil, and woodchips impregnated with bio-oil (10, 20 and 25% on mass basis) were compared. The experiments were carried out by introducing sample into the reaction zone with the flow of N2 and at the temperature range of 300 to 600 ˚C. Pyrolysis of the bio-oil impregnated woodchip gave higher char yield than the pyrolysis of raw woodchip. By the 20% (m/m) bio-oil impregnation, char yield increased by 18.9% (spruce) and 19.1% (birch) on average from the raw woodchip pyrolysis. In addition, the char yield from bio-oil impregnated woodchips was higher than the interpolated char yield of raw woodchips and bio-oil, indicating that synergy effect exists by bio-oil impregnation compared with mere recycling of bio-oil. However, high heating rate corresponded to high temperature pyrolysis, i.e. above 400 ˚C, created cavities and breakages on woodchips, which minimized the secondary reaction. Neither carbon content nor heating value of char was influenced by bio-oil impregnation. Energy yield also showed improvement by increasing bio-oil recycling ratio. For example, energy yield of char from woodchips at the temperature of 340 ˚C increased from 48.4% with raw woodchips to 64.5% by woodchips with 25% of bio-oil impregnation.

  • 54.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Material Science and Environmental Engineering, Tampere University, FI-33720 Tampere, Finland.
    Vila, Ricardo
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Kienzl, Norbert
    BEST─Bioenergy and Sustainable Technologies GmbH, Inffeldgasse 21b, 8010 Graz, Austria.
    Wang, Liang
    SINTEF Energy Research, P.O. Box 4761 Torgarden, 7465 Trondheim, Norway.
    Hedayati, Ali
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Broström, Marcus
    Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory, Umeå University, SE-901 87 Umeå, Sweden.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Engvall, Klas
    Department of Chemical Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Skreiberg, Øyvind
    SINTEF Energy Research, P.O. Box 4761 Torgarden, 7465 Trondheim, Norway.
    Robinson, Ryan
    Global Technology, Höganäs AB, SE-263 83 Höganäs, Sweden.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    CO2 Gasification Reactivity of Char from High-Ash Biomass2021Inngår i: ACS Omega, E-ISSN 2470-1343, Vol. 6, nr 49, s. 34115-34128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass char produced from pyrolysis processes is of great interest to be utilized as renewable solid fuels or materials. Forest byproducts and agricultural wastes are low-cost and sustainable biomass feedstocks. These biomasses generally contain high amounts of ash-forming elements, generally leading to high char reactivity. This study elaborates in detail how chemical and physical properties affect CO2 gasification rates of high-ash biomass char, and it also targets the interactions between these properties. Char produced from pine bark, forest residue, and corncobs (particle size 4–30 mm) were included, and all contained different relative compositions of ash-forming elements. Acid leaching was applied to further investigate the influence of inorganic elements in these biomasses. The char properties relevant to the gasification rate were analyzed, that is, elemental composition, specific surface area, and carbon structure. Gasification rates were measured at an isothermal condition of 800 °C with 20% (vol.) of CO2 in N2. The results showed that the inorganic content, particularly K, had a stronger effect on gasification reactivity than specific surface area and aromatic cluster size of the char. At the gasification condition utilized in this study, K could volatilize and mobilize through the char surface, resulting in high gasification reactivity. Meanwhile, the mobilization of Ca did not occur at the low temperature applied, thus resulting in its low catalytic effect. This implies that the dispersion of these inorganic elements through char particles is an important reason behind their catalytic activity. Upon leaching by diluted acetic acid, the K content of these biomasses substantially decreased, while most of the Ca remained in the biomasses. With a low K content in leached biomass char, char reactivity was determined by the active carbon surface area.

  • 55.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wang, Liang
    SINTEF Energy Research .
    Romar, Henrik
    University of Oulu, Research Unit of Applied Chemistry.
    Broström, Markus
    Umeå University, Department of Applied Physics and Electronics.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Skreiberg, Øyvind
    SINTEF Energy Research .
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Effects of pyrolysis oil recycling and reaction gas atmosphere on the physical properties and reactivity of charcoal from wood2018Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 56.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wang, Liang
    SINTEF Energy Research, Torgarden, Trondheim, Norway.
    Romar, Henrik
    Research Unit of Sustainable Chemistry, Oulu University, Oulu, Finland.
    Kienzl, Norbert
    BEST—Bioenergy and Sustainable Technologies GmbH, Graz, Austria.
    Broström, Markus
    Department of Applied Physics and Electronics, Umeå University, 901 87 Umeå, Sweden.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Skreiberg, Øyvind
    deSINTEF Energy Research, P.O. Trondheim, Norway.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Effects of Pyrolysis Conditions and Feedstocks on the Properties and Gasification Reactivity of Charcoal from Woodchips2020Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 34, nr 7, s. 8353-8365Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pyrolysis conditions in charcoal production affect yields, properties, and further use of charcoal. Reactivity is a critical property when using charcoal as an alternative to fossil coal and coke, as fuel or reductant, in different industrial processes. This work aimed to obtain a holistic understanding of the effects of pyrolysis conditions on the reactivity of charcoal. Notably, this study focuses on the complex effects that appear when producing charcoal from large biomass particles in comparison with the literature on pulverized biomass. Charcoals were produced from woodchips under a variety of pyrolysis conditions (heating rate, temperature, reaction gas, type of biomass, and bio-oil embedding). Gasification reactivity of produced charcoal was determined through thermogravimetric analysis under isothermal conditions of 850 degrees C and 20% of CO2. The charcoals were characterized for the elemental composition, specific surface area, pore volume and distribution, and carbon structure. The analysis results were used to elucidate the relationship between the pyrolysis conditions and the reactivity. Heating rate and temperature were the most influential pyrolysis parameters affecting charcoal reactivity, followed by the reaction gas and bio-oil embedding. The effects of these pyrolysis conditions on charcoal reactivity could primarily be explained by the difference in the meso- and macropore volume and the size and structural order of aromatic clusters. The lower reactivity of slow pyrolysis charcoals also coincided with their lower catalytic inorganic content. The reactivity difference between spruce and birch charcoals appears to be mainly caused by the difference in catalytically active inorganic elements. Contrary to pyrolysis of pulverized biomass, a low heating rate produced a higher specific surface area compared with a high heating rate. Furthermore, the porous structure and the reactivity of charcoal produced from woodchips were influenced when the secondary char formation was promoted, which cannot be observed in pyrolysis of pulverized biomass.

  • 57.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wretborn, Tobias
    Luleå tekniska universitet.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Biomass pyrolysis with bio-oil recycle to increase energy recovery2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study aims at increasing char yield by recycling bio-oil without negative impact on char qualities, i.e. carbon content and heating value. Pyrolysis experiments on spruce and birch chips were carried in a macro-thermogravimetric analyzer. To examine the effect of bio-oil recycle, dried raw woodchips, pure bio-oil, and woodchips impregnated with bio-oil (10, 20 and 25% on mass basis) were compared. The experiments were carried out by introducing sample into the reaction zone with the flow of N2 and at the temperature range of 300 to 600 ˚C. Pyrolysis of the bio-oil impregnated woodchip gave higher char yield than the pyrolysis of raw woodchip. By the 20% (m/m) bio-oil impregnation, char yield increased by 18.9% (spruce) and 19.1% (birch) on average from the raw woodchip pyrolysis. In addition, the char yield from bio-oil impregnated woodchips was higher than the interpolated char yield of raw woodchips and bio-oil, indicating that synergy effect exists by bio-oil impregnation compared with mere recycling of bio-oil. However, high heating rate corresponded to high temperature pyrolysis, i.e. above 400 ˚C, created cavities and breakages on woodchips, which minimized the secondary reaction. Neither carbon content nor heating value of char was influenced by bio-oil impregnation. Energy yield also showed improvement by increasing bio-oil recycling ratio. For example, energy yield of char from woodchips at the temperature of 340 ˚C increased from 48.4% with raw woodchips to 64.5% by woodchips with 25% of bio-oil impregnation.

    Fulltekst (pdf)
    fulltext
  • 58.
    Phounglamcheik, Aekjuthon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wretborn, Tobias
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Increasing efficiency of charcoal production with bio-oil recycling2018Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, nr 9, s. 9650-9658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Charcoal from biomass is a promising alternative for fossil coal. Although its quality increases at high pyrolysis temperature, charcoal yield decreases, meaning lower economic performances of charcoal production processes. This work aims at demonstrating potential methods to increase charcoal yield while keeping its quality at satisfying levels. We suggested the recycling of bio-oil from pyrolysis process as a primary measure. In addition, we also investigated in detail the consequence of utilizing CO2 instead of N2 as reaction media under practical conditions (i.e. thick particles). An experimental investigation was carried out in a macro-thermogravimetric (macro-TG) reactor. Sample (woodchips, bio-oil, and woodchips embedded with bio-oil) was exposed to the reaction temperature either instantaneously (isothermal condition) or by slow heating (slow pyrolysis) in controlled gas flows of N2 and CO2. The results showed that char yield increases with the bio-oil recycling on wood chips at all pyrolysis temperatures (300–700 °C). By 20% of bio-oil embedding on wood chips, charcoal yield increased by 18.3% on average. The increase of charcoal yield was not only because of the increase in reactants, but also due to the synergetic effect between bio-oil and wood chips upon physical contact. Bio-oil recycling had negligible effects on the property of charcoal, such as carbon content and heating value. Although CO2 did not affect primary pyrolysis, it had effects on mass transfer processes. As a result, significantly higher char yield was obtained from pyrolysis in CO2 than in N2 by ensuring a good contact of volatiles and solid surface (i.e. usage of thick particles and slow heating). This study suggests that we can achieve high charcoal yield while maintaining the similar charcoal property by bio-oil recycling, CO2 purging, use of thick particles, and slow heating.

  • 59.
    Pielsticker, Stefan
    et al.
    Institute of Heat and Mass Transfer (WSA), RWTH Aachen University, Aachen, Germany.
    Gövert, Benjamin
    Institute of Heat and Mass Transfer (WSA), RWTH Aachen University, Aachen, Germany.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kneer, Reinhold
    Institute of Heat and Mass Transfer (WSA), RWTH Aachen University, Aachen, Germany.
    Flash Pyrolysis Kinetics of Extracted Lignocellulosic Biomass Components2021Inngår i: Frontiers in Energy Research, E-ISSN 2296-598X, Vol. 9, artikkel-id 737011Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass is a complex material mainly composed of the three lignocellulosic components: cellulose, hemicellulose and lignin. The different molecular structures of the individual components result in various decomposition mechanisms during the pyrolysis process. To understand the underlying reactions in more detail, the individual components can be extracted from the biomass and can then be investigated separately. In this work, the pyrolysis kinetics of extracted and purified cellulose, hemicellulose and lignin are examined experimentally in a small-scale fluidized bed reactor (FBR) under N2 pyrolysis conditions. The FBR provides high particle heating rates (approx. 104 K/s) at medium temperatures (573–973 K) with unlimited reaction time and thus complements typically used thermogravimetric analyzers (TGA, low heating rate) and drop tube reactors (high temperature and heating rate). Based on the time-dependent gas concentrations of 22 species, the release rates of these species as well as the overall rate of volatiles released are calculated. A single first-order (SFOR) reaction model and a 2-step model combined with Arrhenius kinetics are calibrated for all three components individually. Considering FBR and additional TGA experiments, different reaction regimes with different activation energies could be identified. By using dimensionless pyrolysis numbers, limits due to reaction kinetics and heat transfer could be determined. The evaluation of the overall model performance revealed model predictions within the ±2σ standard deviation band for cellulose and hemicellulose. For lignin, only the 2-step model gave satisfying results. Modifications to the SFOR model (yield restriction to primary pyrolysis peak or the assumption of distributed reactivity) were found to be promising approaches for the description of flash pyrolysis behavior, which will be further investigated in the future.

     

  • 60.
    Prabowo, Bayu
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Aziz, Muhammad
    Solutions Research Laboratory, Tokyo Institute of Technology.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Susanto, Herri
    Department of Chemical Engineering, Institut Teknologi Bandung.
    Yan, Mi
    State Key Laboratory of Clean Energy Utilization, Zhejiang University.
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Tokyo Institute of Technology.
    CO2-recycling biomass gasification system for highly efficient and carbon-negative power generation2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 158, s. 97-106, artikkel-id 6848Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study explored the feasibility of biomass CO2 gasification as an effective method for implementing the concept of a carbon-negative power system through bioenergy with carbon capturing and storage. A CO2-recycling biomass gasification system was developed and examined using the thermal equilibrium model. Sensitivity analysis was performed by varying the gasifier temperature from 750 to 950 °C, and the turbine inlet temperature (TIT) and turbine exit temperature (TET) of the gas turbine from 1000 to 1200 °C and from 900 to 1000 °C, respectively. The gasifier efficiency was increased by an increase in the CO2 recycling ratio with the more significant trend shown at the lower gasifier temperature. The turbine efficiency decreased as the CO2 recycling ratio to the gasifier increased over a certain limit, a ratio of 0.55 in most cases. A pressure ratio of 2.3 was optimum in terms of turbine efficiency. Under the examined conditions, the optimum conditions for gaining the highest system efficiency, 39.03%, were a recycling ratio of 0.55 and a TET and TIT of 1000 and 1200 °C respectively. The proposed system had 7.57% higher efficiency and exhausted 299.15 g CO2/kW h less CO2 emissions than conventional air gasification. Combined with carbon capturing and storage, the system potentially generates carbon-negative power generation with intensity of around 1.55-kg CO2/kg wet-biomass and a maximum efficiency penalty of 6.89%.

  • 61.
    Prabowo, Bayu
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Institute of Energy and Power Engineering, Zhejiang University of Technology.
    Aziz, Muhammad
    Solutions Research Laboratory, Tokyo Institute of Technology.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yan, Mi
    State Key Laboratory of Clean Energy Utilization, Zhejiang University, Institute of Energy and Power Engineering, Zhejiang University of Technology.
    Susanto, Herri
    Institute Technology of Bandung, Department of Chemical Engineering.
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology.
    Utilization of Rice Husk in the CO2-Recycling Gasification System for the Effective Implementation of Bioenergy with Carbon Capture and Storage (BECCS) Technology2015Inngår i: Advances in CO₂ capture, sequestration, and conversion / [ed] Fangming Jin; Liang-Nian He; Yun Hang Hu, Washington, DC: American Chemical Society (ACS), 2015, s. 323-340Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A biomass gasification system with CO2-recycling was developed and examined using the thermal equilibrium model. Performance comparison was conducted against the conventional air gasification system. Sensitivity analyses were performed by varying the gasifier temperature from 750 degrees C to 950 degrees C and testing three kinds of rice husk as feedstock: As harvested, naturally dried, or torrefied. The proposed system produced 7.5 % higher efficiency than the conventional air gasification. Moreover, the system exhausted 302 g-CO2/kWh lower emission and in the form of high purity of CO2 stream that is favorable for sequestration process. The recycled CO2 from the gas turbine acted as an effective heat source for the gasifier as well as gasifying agent. The positive effect of CO2-recycling was more prominent at the lower gasifier temperature. The utilization of high quality feedstock, i.e. low moisture content and low O/C ratio, was favorable for optimizing the effect of CO2-recycling on the system efficiency. Under the examined conditions, the optimum conditions for gaining the highest system efficiency, 39,4%, were a gasifier temperature of 850 degrees C with CO2 recycling ratio of 0.87 and the torrefied feedstock. Application of carbon capture and storage process to the system at the optimum condition resulted in 1.75 kg-CO2/kg-dry-biomass negative carbon intensity with merely 6.5% efficiency penalty. These results show that the CO2-recycling gasification system is promising for effectively applying BECCS concept.

  • 62.
    Prabowo, Bayu
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Susanto, Herri
    Department of Chemical Engineering, Institut Teknologi Bandung.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yan, Mi
    State Key Laboratory of Clean Energy Utilization, Zhejiang University, Institute of Energy and Power Engineering, Zhejiang University of Technology.
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology.
    Pilot scale autothermal gasification of coconut shell with CO2-O2 mixture2015Inngår i: Frontiers in Energy, ISSN 2095-1701, E-ISSN 2095-1698, Vol. 9, nr 3, s. 362-370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper explored the feasibility and benefit of CO2 utilization as gasifying agent in the autothermal gasification process. The effects of CO2 injection on reaction temperature and producer gas composition were examined in a pilot scale downdraft gasifier by varying the CO2/C ratio from 0.6 to 1.6. O2 was injected at an equivalence ratio of approximately 0.33–0.38 for supplying heat through partial combustion. The results were also compared with those of air gasification. In general, the increase in CO2 injection resulted in the shift of combustion zone to the downstream of the gasifier. However, compared with that of air gasification, the long and distributed high temperature zones were obtained in CO2-O2 gasification with a CO2/C ratio of 0.6–1.2. The progress of the expected CO2 to CO conversion can be implied from the relatively insignificant decrease in CO fraction as the CO2/C ratio increased. The producer gas heating value of CO2-O2 gasification was consistently higher than that of air gasification. These results show the potential of CO2-O2 gasification for producing high quality producer gas in an efficient manner, and the necessity for more work to deeply imply the observation

  • 63.
    Prabowo, Bayu
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yan, Mi
    State Key Laboratory of Clean Energy Utilization, Zhejiang University.
    Nakamura, Masato R.
    Department of Mechanical Engineering and Industrial Design Technology, New York City College of Technology (City Tech), City University of New York (CUNY).
    Castradi, Marco J.
    Department of Chemical Engineering, The City College of New York, City University of New York (CUNY).
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    CO2–steam mixture for direct and indirect gasification of rice straw in a downdraft gasifier: Laboratory-scale experiments and performance prediction2014Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 113, s. 670-679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper explored the feasibility of CO2 as alternative gasifying agent of steam to obtain higher thermal efficiency in biomass gasification. The effect of the gasifying agent on gas evolution and thermal efficiency was examined by using a lab scale downdraft gasifier. The results were also compared with the output of pyrolysis with N2. The reaction atmosphere in indirect and direct gasification was simulated by carrying out the experiments without and with O2 presence. The reaction conditions were varied in the temperature range from 750 °C to 950 °C by changing the CO2 molar fraction in gasifying agent to the ratio of 0, 30 and 60 vol.% in balance with steam. 40 vol.% of N2 fraction was kept during O2 free experiments, while 31.7 vol.% of N2 and 8.3 vol.% O2 were kept during the experiments with the presence of O2. At all examined condition, gasification yielded more combustible gas than pyrolysis. Furthermore, high CO2 fraction in gasifying agent generally resulted in low H2 yield and high CO yield. These substitutions mostly lowered the energy yield of the producer gas, but in the other hand also reduced the preheating energy of gasifying agent. Thus, optimizations of these changes were investigated for gaining highest thermal efficiency of the gasification process. Highest thermal efficiency of the process without O2 was 52% under N2 (40 vol.%)–CO2 (60 vol.%) atmosphere at the temperature of 850 °C. For the process with O2, where the part of gasifying agent preheating energy supplied by the biomass partial combustion, the highest thermal efficiency was 60% under the CO2 (60 vol.%)–O2 (8.3 vol.%)–N2 (31.7 vol.%) atmosphere at the temperature of 950 °C. CO2 utilization as a gasifying agent potentially increases the thermal efficiency of biomass conversion process compared with pyrolysis or conventional indirect and direct gasification, i.e. pure-steam gasification and O2–steam gasification.

  • 64.
    Samuelsson, Lina N.
    et al.
    Department of Chemical Engineering and Technology, KTH Royal Institute of Technology.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Babler, Matthaus U.
    Department of Chemical Engineering and Technology, KTH Royal Institute of Technology.
    Mass loss rates for wood chips at isothermal pyrolysis conditions: A comparison with low heating rate powder data2017Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 158, s. 26-34Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 65.
    Schiemann, M.
    et al.
    Department of Energy Plant Technology, Ruhr-University Bochum, 44801, Bochum, Germany.
    Böhm, B.
    Technical University of Darmstadt, Department of Mechanical Engineering, Reactive Flows and Diagnostics, Otto-Berndt-Str. 3, 64287, Darmstadt, Germany.
    Chirone, R.
    STEMS, Consiglio Nazionale delle Ricerche, P.le Tecchio 80, 80125, Naples, Italy.
    Senneca, O.
    STEMS, Consiglio Nazionale delle Ricerche, P.le Tecchio 80, 80125, Naples, Italy.
    Ströhle, J.
    Institute for Energy Systems and Technology, TU Darmstadt, Germany.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Vujanovic, M.
    Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000, Zagreb, Croatia.
    Technical solutions to foster the global energy transition: Special issue on clean fuel conversion technologies for carbon dioxide and pollutant reduction2022Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 154, artikkel-id 111770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the field of energy supply, the focus is shifting from conventional combustion to a variety of new energy conversion technologies. Nineteen articles in this Special Issue describe different aspects, that make combustion and combustion products attractive in the context of future sustainable energy systems. Carbon capture and recycling can bridge the current energy system and the transition to 100% renewables. The energy storage required for this is possible with combustion systems and specific synthetic fuels. In this context, bio-based fuel applications also benefit from current research and support flexible and efficient reduction of carbon dioxide emissions. All these aspects call for better experimental and numerical methods for process characterization and design.

  • 66.
    Schneider, Christoph
    et al.
    Karlsruhe Institute of Technology, Engler-Bunte-Institute, Fuel Technology, EBI ceb, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany.
    Walker, Stella
    Karlsruhe Institute of Technology, Engler-Bunte-Institute, Fuel Technology, EBI ceb, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany.
    Phounglamcheik, Aekjuthon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kolb, Thomas
    Karlsruhe Institute of Technology, Engler-Bunte-Institute, Fuel Technology, EBI ceb, Engler-Bunte-Ring 1, 76131 Karlsruhe, Germany. Karlsruhe Institute of Technology, Institute for Technical Chemistry, ITC vgt, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
    Effect of calcium dispersion and graphitization during high-temperature pyrolysis of beech wood char on the gasification rate with CO22021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 283, artikkel-id 118826Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents thermal deactivation of beech wood chars during secondary pyrolysis in a drop-tube reactor. Pyrolysis temperature was varied between 1000 °C and 1600 °C at a constant residence time of 200 ms. The effect of pyrolysis conditions on initial conversion rate R0 during gasification, graphitization of the carbon matrix and ash morphology was investigated. Gasification experiments for the determination of R0 were conducted in a thermogravimetric analyzer using pure CO2 at 750 °C and isothermal conditions. A linear decrease in initial conversion rate R0 was observed between 1000 °C and 1400 °C. However, a strong increase of R0 at 1600 °C was encountered. Micropore surface area of the secondary chars showed no correlation with the initial conversion rate R0 during gasification with CO2. Graphitization of the carbon matrix was determined using X-ray diffraction and Raman spectroscopy suggesting the growth of aromatic clusters and graphite-like structures for increasing pyrolysis temperatures up to 1600 °C. Furthermore, CaO dispersion was analyzed quantitatively and qualitatively using temperature-programmed reaction at 300 °C as well as SEM/TEM. CaO dispersion DCaO decreases steadily between 1000 °C and 1400 °C whereas a strong increase can be observed at 1600 °C, which is in good accordance with the development of the initial conversion rate R0 as a function of pyrolysis temperature. SEM/TEM images indicate the formation of a thin CaO layer at 1600 °C that is presumably responsible for the strong increase in initial conversion rate R0 at this temperature. When excluding the catalytic activity of CaO via formation of the ratio R0 DCaO−1, increasing graphitization degree has a linear negative influence on char reactivity at pyrolysis temperatures between 1000 °C and 1400 °C.

  • 67.
    Strandberg, Anna
    et al.
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory.
    Holmgren, Per
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory.
    Wagner, David R.
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory.
    Molinder, Roger
    RISE Energy Technology Center.
    Wiinikka, Henrik
    RISE Energy Technology Center.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Broström, Markus
    Umeå University, Department of Applied Physics and Electronics, Thermochemical Energy Conversion Laboratory.
    Effects of pyrolysis conditions and ash formation on gasification rates of biomass char2017Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, nr 6, s. 6507-6514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pyrolysis conditions and the presence of ash-forming elements significantly influence char properties and its oxidation or gasification reactivity. In this study, intrinsic gasification rates of char from high heating rate pyrolysis were analyzed with isothermal thermogravimetry. The char particles were prepared from two biomasses at three size ranges and at two temperatures. Reactivity dependence on original particle size was found only for small wood particles that had higher intrinsic char gasification rates. Pyrolysis temperature had no significant effect on char reactivity within the range tested. Observations of ash formation highlighted that reactivity was influenced by the presence of ash-forming elements, not only at the active char sites but also through prohibition of contact between char and gasification agent by ash layer formation with properties highly depending on ash composition.

  • 68.
    Tanaka, Yasuto
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Mesfun, Sennai
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Toffolo, Andrea
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Tamura, Yutaka
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama.
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama, Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology.
    Thermodynamic performance of a hybrid power generation system using biomass gasification and concentrated solar thermal processes2015Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 160, s. 664-672Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the investigation of a hybrid power production system from biomass and solar energy. This paper suggests integration through heat exchanger network as a useful approach to obtain the synergy between biomass and solar. Biomass is first gasified in a bubbling fluidized bed (BFB) gasifier, and then syngas is used in a gas turbine. Excess heat exists in this sub-system and concentrated solar thermal process (CSTP) while there is a demand of steam for generating gasifying agent. Steam Rankine cycle exploits the heat created by these thermal streams to generate power while satisfying the steam demands. Thermodynamic performance was analyzed by process modelling with a semi-kinetic model of BFB gasifier and pinch analyses. The composition and temperature of gasifying agent showed some effect on the overall efficiency of the system. Higher overall efficiency of the system was achieved at higher temperature and higher O2 fraction in the O2-steam mixture as gasifying agent. The increase in thermal input from CSTP had positive effect on overall efficiency of the hybrid system until thermal input from CSTP becomes dominant against thermal stream related to the gasifier and the gas turbine.

  • 69.
    Tanaka, Yasuto
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Tamura, Yutaka
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama.
    Yoshikawa, Kunio
    Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology.
    Performance of a Hybrid Power Generation System Using Biomass Gasification and Concentrated Solar Thermal Processes2014Inngår i: Energy Procedia, ISSN 1876-6102, Vol. 61, s. 2149-2153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hybrid power generation system using biomass gasification and concentrated solar thermal processes (CSTP) was proposed. We analysed the system performance of a combined cycle with a bubbling fluidized bed gasifier (BFG) using CO2-H2O-O2 mixture and CSTP using molten salt. BFG was simulated by a semi-kinetic model, applying a continuously stirred tank reactor (CSTR) model for the bed behaviour and a plug flow reactor (PFR) model for the freeboard reactions. Operating conditions of the plant and heat exchanger network were optimized separately. The current paper shows the effects of gasifying agents and heat input from CSTP on system efficiency among examined parameters. Pure steam at the molar ratio of steam to carbon in biomass around 0.5 was optimum gasifying agent in this system. By increasing heat input from CSTP, marginal efficiency of biomass-to-electricity was enhanced by 6.2-6.5% (from 39.9 ∼41.2% to 46.1∼47.5%).

  • 70.
    Toloue Farrokh, Najibeh
    et al.
    Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland.
    Suopajärvi, Hannu
    Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland.
    Mattila, Olli
    Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Phounglamcheik, Aekjuthon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Romar, Henrik
    Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
    Sulasalmi, Petri
    Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland.
    Fabritius, Timo
    Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland.
    Slow pyrolysis of by-product lignin from wood-based ethanol production– A detailed analysis of the produced chars2018Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 164, s. 112-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Slow pyrolysis as a method of producing a high-quality energy carrier from lignin recovered from wood-based ethanol production has not been studied for co-firing or blast furnace (BF) applications up to now. This paper investigates fuel characteristics, grindability, moisture uptake and the flow properties of lignin chars derived from the slow pyrolysis of lignin at temperatures of 300, 500 and 650 °C (L300, L500 and L650 samples respectively) at a heating rate of 5 °C min-1. The lignin chars revealed a high mass and energy yield in the range of 39-73% and 53-89% respectively. Pyrolysis at 500 °C or higher, yielded lignin chars with low H/C and O/C ratios suitable for BF injection. Furthermore, the hydrophobicity of lignin was improved tremendously after pyrolysis. Pyrolysis at high temperatures increased the sphericity of the lignin char particles and caused some agglomeration in L650. Large and less spherical particles were found to be a reason for high permeability, compressibility and cohesion of L300 in contrast to L500 and L650. L300 and L500 chars demonstrated high combustibility with low ignition and burnout temperatures. Also, rheometric analysis showed that L500 has the best flow properties including low aeration energy and high flow function.

  • 71.
    Trubetskaya, Anna
    et al.
    Thermochemical Energy Conversion Laboratory , Umeå University.
    Broström, Markus
    Thermochemical Energy Conversion Laboratory (TEC-Lab), Department of Applied Physics and Electronics, Umeå University.
    Kling, Jens
    Center for Electron Nanoscopy , Technical University of Denmark.
    Brown, Avery
    Chemical Engineering Department, Worcester Polytechnic Institute.
    Tompsett, Geoffrey
    Chemical Engineering Department, Worcester Polytechnic Institute.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Effects of Lignocellulosic Compounds on the Yield, Nanostructure and Reactivity of Soot from Fast Pyrolysis at High Temperatures2017Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Gasification offers the utilization of biomass to a wide variety of applications such as heat, electricity, chemicals and transport fuels in an efficient and sustainable manner. High soot yields in the high-temperature entrained flow gasification lead to intensive gas cleaning and can cause a possible plant shut down. The reduction of soot formation increases the overall production system efficiency and improves the economic feasibility and reliability of the gasification plant. The aim of this work is to present the effect of lignocellulosic compoundson the yield, nanostructure and reactivity of soot. Soot was produced from holocelluloses, extractives, two types of organosolv lignin (softwood and wheat straw), and lignin-derived compounds (syringol, guaiacol, p-hydroxyphenol)at temperature of 1250°Cand residence time of 0.17 sand 0.35 sin a drop tube furnace.Soxhlet extraction was performed on soot samples from pyrolysis of both lignin samplesusing acetone and methanol as a solvent.The structure of solid residues was characterized by transmission electron microscopy and Raman spectroscopy. The reactivity of soot inO2oxidation and CO2gasificationwas investigated by thermogravimetric analysis. The present results indicated that soot yields from pyrolysis of ligninfrom softwood and extractives at 1250°C with the residence time of 0.17 swere similaras shown in Figure 1. The highest soot yield was obtained from pyrolysis of wheat straw lignin and quantitatively comparable with the soot yield of hydroquinone. The presence of hydroxyl groups compared to other lignin-derived compounds representing S-and G-lignin types might enhance the soot formation.Lower soot yields were obtained from pyrolysis of cellulose and hemicellulosedue to the lower presence of inherent aromatic rings [1-3].Moreover, the soot yields from pyrolysis of potassium impregnated lignin at 1250°C with the residence time of 0.35 swere significantly lower than that of non-treated lignin samples indicating the catalytic influence of potassium inhibitinggrowth of polycyclic aromatic hydrocarbons, confirming the previous results of Umeki et al. [4]

    Fulltekst (pdf)
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  • 72.
    Trubetskaya, Anna
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. DTU Chemical Engineering, Green Research Center, Lyngby, 2800, Denmark; Technical University of Denmark, Chemical Engineering Department, Combustion and Harmful Emission Control Group, Søltofts Plads, Bygning 229, Lyngby, 2800, Denmark.
    Garcia Llamas, Angel David
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jensen, Peter Arendt
    DTU Chemical Engineering, Green Research Center, Lyngby, 2800, Denmark.
    Jensen, Anker Degn
    DTU Chemical Engineering, Green Research Center, Lyngby, 2800, Denmark.
    Glarborg, Peter
    DTU Chemical Engineering, Green Research Center, Lyngby, 2800, Denmark.
    Effect of Fast Pyrolysis Conditions on the Biomass Solid Residues at High Temperatures (1000-1400°C)2015Inngår i: Forest and Plant Bioproducts Division 2015 - Core Programming Area at the 2015 AIChE Annual Meeting, American Institute of Chemical Engineers , 2015, s. 177-184Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
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  • 73.
    Trubetskaya, Anna
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. hermochemical Energy Conversion Laboratory, Umeå University.
    Hofmann Larsen, Flemming
    Department of Food Science, University of Copenhagen.
    Shchukarev, Andrey
    Department of Chemistry, Umeå University.
    Ståhl, Kenny
    Department of Chemistry, Technical University of Denmark.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Potassium and soot interaction in fast biomass pyrolysis at high temperatures2018Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 225, s. 89-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    his study aims to investigate the interaction between potassium and carbonaceous matrix of soot produced from wood and herbaceous biomass pyrolysis at high heating rates at 1250°C in a drop tube reactor. The influence of soot carbon chemistry and potassium content in the original biomass on the CO2 reactivity was studied by thermogravimetric analysis. The XPS results showed that potassium incorporation with oxygen-containing surface groups in the soot matrix did not occur during high temperature pyrolysis. The potassium was mostly found as water-soluble salts such as KCl, KOH, KHCO3 and K2CO3 in herbaceous biomass soot. The low ash-containing pinewood soot was less reactive than the potassium rich herbaceous biomass soot, indicating a dominating role of potassium on the soot reactivity. However, the catalytic effect of potassium on the reactivity remained the same after a certain potassium amount was incorporated in the soot matrix during pyrolysis. Raman spectroscopy results showed that the carbon chemistry of biomass soot also affected the CO2 reactivity. The less reactive pinewood soot was more graphitic than herbaceous biomass soot samples with the disordered carbon structure.

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  • 74.
    Trubetskaya, Anna
    et al.
    Mechanical Engineering Department, National University of Ireland Galway.
    Hofmann Larsen, Flemming
    Department of Food Science, University of Copenhagen.
    Shchukarev, Andrey
    Department of Chemistry, Umeå University.
    Ståhl, Kenny
    Department of Chemistry, Technical University of Denmark.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Potassium and soot interaction in fast biomass pyrolysis at high temperatures2018Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
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  • 75.
    Trubetskaya, Anna
    et al.
    Department of Chemical Sciences, University of Limerick, Limerick, Ireland.
    Hunt, Andrew J.
    Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, 123 Mittraparb Road, 40002 Khon Kaen, Thailand.
    Budarin, Vitaliy L.
    Department of Chemistry, The University of York, Heslington, York YO10 5DD, UK.
    Attard, Tomas M.
    Department of Chemistry, The University of York, Heslington, York YO10 5DD, UK.
    Kling, Jens
    Center for Electron Nanoscopy, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
    Surup, Gerrit R.
    Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
    Arshadi, Mehrdad
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Supercritical extraction and microwave activation of wood wastes for enhanced syngas production and generation of fullerene-like soot particles2021Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 212, artikkel-id 106633Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work demonstrated that supercritical carbon dioxide extraction is effective as a pre-treatment technology to generate soot particles with the fullerene-like structure and increase syngas yield from extracted residues during coupled microwave activation with gasification. Supercritical carbon dioxide extraction removes over half of the fatty and resin acids from needles and branches, whereas the extraction of needles generates greater yields of value-added compounds. The high yields of extractives indicate the effective conversion of waste wood for the sustainable production of value-added chemicals. The wood extraction did not influence the solid residue yields during pyrolysis/gasification emphasizing the significant potential of integrating the extraction process into the holistic biorefinery. Interestingly, supercritical carbon dioxide extraction had a significant effect on the structure and quality of soot particles formed. The differences in the extractives composition led to the formation of needle soot particles with a porous and less ordered nanostructure, whereas the soot branches obtained a ring graphitic structure. The greater yields of steroids and terpenes during the extraction of needles compared to the branches pretreatment indicated the influence of the extractives type on the soot nanostructure. © 2020 The Author(s)

  • 76.
    Trubetskaya, Anna
    et al.
    DTU Chemical Engineering, Technical University of Denmark.
    Jensen, Peter Arendt
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Glarborg, Peter
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Garcia Llamas, Angel David
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kling, Jens
    Center for Electron Nanoscopy , Technical University of Denmark.
    Gardini, Diego
    Center for Electron Nanoscopy , Technical University of Denmark.
    Bates, Richard B.
    MIT, Department of Mechanical Engineering.
    Jensen, Anker Degn
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Effects of Biomass Feedstock on the Yield and Reactivity of Soot from Fast Pyrolysis at High Temperatures2016Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
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  • 77.
    Trubetskaya, Anna
    et al.
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Jensen, Peter Arendt
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Jensen, Anker Degn
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Llamas, Angel David Garcia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gardini, Diego
    Center for Electron Nanoscopy, Technical University of Denmark.
    Kling, Jens
    Center for Electron Nanoscopy, Technical University of Denmark.
    Bates, Richard B.
    MIT, Department of Mechanical Engineering, 02139 Cambridge.
    Glarborg, Peter
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Effects of several types of biomass fuels on the yield, nanostructure and reactivity of soot from fast pyrolysis at high temperatures2016Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 171, s. 468-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents the effect of biomass origin on the yield, nanostructure and reactivity of soot. Soot was produced from wood and herbaceous biomass pyrolysis at high heating rates and at temperatures of 1250 and 1400 °C in a drop tube furnace. The structure of solid residues was characterized by electron microscopy techniques, X-ray diffraction and N2 adsorption. The reactivity of soot was investigated by thermogravimetric analysis. Results showed that soot generated at 1400 °C was more reactive than soot generated at 1250 °C for all biomass types. Pinewood, beechwood and wheat straw soot demonstrated differences in alkali content, particle size and nanostructure. Potassium was incorporated in the soot matrix and significantly influenced soot reactivity. Pinewood soot particles produced at 1250 °C had a broader particle size range (27.2–263 nm) compared to beechwood soot (33.2–102 nm) and wheat straw soot (11.5–165.3 nm), and contained mainly multi-core structures.

  • 78.
    Trubetskaya, Anna
    et al.
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Jensen, Peter Arendt
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Jensen, Anker Degn
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Llamas, Angel David Garcia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Glarborg, Peter
    Department of Chemical and Biochemical Engineering, Technical University of Denmark.
    Effect of fast pyrolysis conditions on biomass solid residues at high temperatures2016Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 143, s. 118-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fast pyrolysis of wood and straw was conducted in a drop tube furnace (DTF) and compared with corresponding data from a wire mesh reactor (WMR) to study the influence of temperature (1000-1400)°C, biomass origin (pinewood, beechwood, wheat straw, alfalfa straw), and heating rate (103 °C/s, 104 °C/s) on the char yield and morphology. Scanning electron microscopy (SEM), elemental analysis, and ash compositional analysis were applied to characterize the effect of operational conditions on the solid residues (char, soot) and gaseous products. The char yield from fast pyrolysis in the DTF setup was 3 to 7% (daf) points lower than in the WMR. During fast pyrolysis pinewood underwent drastic morphological transformations, whereas beechwood and straw samples retained the original porous structure of the parental fuel with slight melting on the surface. The particle size of Danish wheat straw char decreased in its half-width with respect to the parental fuel, whereas the alfalfa straw char particle size remained unaltered at higher temperatures. Soot particles in a range from 60 to 300 nm were obtained during fast pyrolysis. The soot yield from herbaceous fuels was lower than from wood samples, possibly due to differences in the content of lignin and resin acids

  • 79.
    Trubetskaya, Anna
    et al.
    Mechanical Engineering Department, National University of Ireland Galway.
    Kling, Jens
    Center for Electron Nanoscopy, Technical University of Denmark.
    Broström, Markus
    Thermochemical Energy Conversion Laboratory (TEC-Lab), Department of Applied Physics and Electronics, Umeå University.
    Tompsett, Geoffrey
    Chemical Engineering Department, Worcester Polytechnic Institute.
    Timko, Michael T.
    Chemical Engineering Department, Worcester Polytechnic Institute.
    Brown, Avery
    Chemical Engineering Department, Worcester Polytechnic Institute.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Andersen, Mogens Larsen
    Department of Food Science, University of Copenhagen.
    The effect of lignocellulosic compounds and monolignols on the soot nanostructure and CO2 reactivity2018Konferansepaper (Fagfellevurdert)
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  • 80. Trubetskaya, Anna
    et al.
    Kling, Jens
    Center for Electron Nanoscopy, Technical University of Denmark.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Attard, Thomas M.
    Department of Chemistry, The University of York.
    Budarin, Vitaliy L.
    Department of Chemistry, The University of York.
    Hunt, Andrew J.
    Department of Chemistry, Khon Kaen University.
    Effect of supercritical extraction on the soot nanostructure and gasification product yields2018Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 81.
    Trubetskaya, Anna
    et al.
    School of Engineering and Ryan Institute, National University of Ireland Galway, Galway, Ireland.
    Souihi, Nabil
    Green Technologies and Environmental Economics Platform, Department of Chemistry, Umeå University, Umeå, Sweden.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Categorization of tars from fast pyrolysis of pure lignocellulosic compounds at high temperature2019Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 141, s. 751-759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents how the yields of different tar compounds from pure lignocellulosic compounds respond to the change in temperature and residence time. Experiments were carried out with a drop tube furnace in the temperature range from 800 to 1250 °C. The tar composition was characterized by gas chromatography with a flame ionization detector and mass spectrometry using a dual detector system. Longer residence time and higher heat treatment temperatures increased the soot formation and decreased the tar yields. Soot yields from lignin samples were greater than soot yields from holocellulose pyrolysis. The dominating products in tars from pyrolysis of all lignocellulosic compounds were benzene and toluene. Cellulose and hemicellulose pyrolysis produced greater amount of oxygenates in tars, whereas lignin tar was rich in phenols, polycyclic hydrocarbons and naphthalenes. Simultaneous reduction of tar and soot was achieved by impregnation of lignin from wheat straw with alkali metals. The OPLS-DA model can accurately explain the differences in tar composition based on the experimental mass spectrometry data.

  • 82.
    Trubetskaya, Anna
    et al.
    School of Engineering and Ryan Institute, National University of Ireland Galway, Galway, Ireland.
    Timko, Michael T.
    Chemical Engineering Department, Worcester Polytechnic Institute, Worcester, MA, USA.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Prediction of fast pyrolysis products yields using lignocellulosic compounds and ash contents2020Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 257, artikkel-id 113897Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of lignocellulosic biomass composition on product yields and distributions were studied under high-temperature pyrolysis conditions (800–1250 °" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">°°C) in a drop tube reactor. Several types of biomass were studied along with xylan, cellulose, and two types of lignin as model feeds. Among the model feeds, soot yields obtained from lignin pyrolysis were greater than those obtained from cellulose or xylan. Cellulose pyrolysis produced mostly gaseous products, along with small amounts of tars. Impregnation of lignin with alkali metals greatly reduced tar and soot formation, simultaneously increasing the hydrogen content of the syngas product. An empirical model predicted with reasonable accuracy trends in the product yields obtained from pyrolysis of whole biomass samples using as input data obtained from model feeds composition data and the pyrolysis temperature. Reaction temperature and ash content both have a strong influences on char yield, whereas gas yields were mostly affected by the reaction temperature.

  • 83.
    Trubetskaya, Anna
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Chracterization and prediction of tar formation from fast pyrolysis of lignin2017Inngår i: Combustion Flame Days 2017, 2017Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 84.
    Trubetskaya, Anna
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. DTU Chemical Engineering, Green research center.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Garcia Llamas, Angel David
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    jensen, Anker Degn
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Jensen, Peter Arendt
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Glarborg, Peter
    Department of Chemical and Biochemical Engineering, Denmark Technical University.
    Effect of Fast Pyrolysis Conditions on Structural Transformation and Reactivity of Herbaceous Biomasses at High Temperatures2015Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 85.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dataset - Self-Heating of Biochar during Postproduction Storage by O2 Chemisorption at Low Temperatures2022Dataset
    Abstract [en]

    Biochar is attracting attention as an alternative carbon/fuel source to coal in the process industry and energy sector. However, it is prone to self-heating and often leads to spontaneous ignition and thermal runaway during storage, resulting in production loss and health risks. This study investigates biochar self-heating upon its contact with O2 at low temperatures, i.e., 50–300 °C. First, kinetic parameters of O2 adsorption and CO2 release were measured in a thermogravimetric analyzer using biochar produced from a pilot-scale pyrolysis process. Then, specific heat capacity and heat of reactions were measured in a differential scanning calorimeter. Finally, a one-dimensional transient model was developed to simulate self-heating in containers and gain insight into the influences of major parameters. The model showed a good agreement with experimental measurement in a closed metal container. It was observed that char temperature slowly increased from the initial temperature due to heat released during O2 adsorption. Thermal runaway, i.e., self-ignition, was observed in some cases even at the initial biochar temperature of ca. 200 °C. However, if O2 is not permeable through the container materials, the temperature starts decreasing after the consumption of O2 in the container. The simulation model was also applied to examine important factors related to self-heating. The results suggested that self-heating can be somewhat mitigated by decreasing the void fraction, reducing storage volume, and lowering the initial char temperature. This study demonstrated a robust way to estimate the cooling demands required in the biochar production process.

    Fulltekst (zip)
    data set
  • 86.
    Umeki, Kentaro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Häggström, Gustav
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bach-Oller, Albert
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kirtania, Kawnish
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Furusjö, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reduction of tar and soot formation from entrained-flow gasification of woody biomass by alkali impregnation2017Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, nr 5, s. 5104-5110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tar and soot in product gas have been a major technical challenge toward the large-scale industrial installation of biomass gasification. This study aims at demonstrating that the formation of tar and soot can be reduced simultaneously using the catalytic activity of alkali metal species. Pine sawdust was impregnated with aqueous K2CO3 solution by wet impregnation methods prior to the gasification experiments. Raw and alkali-impregnated sawdust were gasified in a laminar drop-tube furnace at 900–1400 °C in a N2–CO2 mixture, because that creates conditions representative for an entrained-flow gasification process. At 900–1100 °C, char, soot and tar decreased with the temperature rise for both raw and alkali-impregnated sawdust. The change in tar and soot yields indicated that potassium inhibited the growth of polycyclic aromatic hydrocarbons and promoted the decomposition of light tar (with 1–2 aromatic rings). The results also indicated that the catalytic activity of potassium on tar decomposition exists in both solid and gas phases. Because alkali salts can be recovered from product gas as an aqueous solution, alkali-catalyzed gasification of woody biomass can be a promising process to produce clean product gas from the entrained-flow gasification process at a relatively low temperature.

  • 87.
    Umeki, Kentaro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Kirtania, Kawnish
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. Monash University, Melbourne, VIC.
    Chen, Luguang
    Monash University, Melbourne, VIC.
    Bhattacharya, Sankar
    Monash University, Melbourne, VIC.
    Fuel particle conversion of pulverized biomass during pyrolysis in an entrained flow reactor2012Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 51, nr 43, s. 13973-13979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study addresses the change of char morphology and fuel conversion during pyrolysis in a laminar entrained flow reactor by experiments and particle simulation. Three experimental parameters were examined: reaction temperature (1073 and 1273 K); particle size (125–250, 250–500, and 500–1000 μm); and the length of reaction zone (650 and 1885 mm). The scanning electron microscopic (SEM) images showed that biomass swelled during heating and shrank during initial stage of pyrolysis. Then, char morphology transformed to cenospheres after the plastic stage. The yields of solid residue from the experiments were reasonably predicted by particle simulation. To give a guideline for the design of laminar entrained flow pyrolysis reactors, the required reactor length for complete conversion of biomass was also calculated for the pyrolysis. High reaction temperature, small particles, and slower gas flow were favorable for high fuel conversion.

  • 88.
    Umeki, Kentaro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Moilanen, Antero
    VTT Technical Research Centre of Finland, Espoo.
    Gόmez-Barea, Alberto
    University of Seville.
    Konttinen, Jukka
    University of Jyväskylä.
    A model of biomass char gasification describing the change in catalytic activity of ash2012Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 207-208, s. 616-624Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A comprehensive description of catalytic effects during chargasification under various conditions relevant for biomassgasification was made. A three-parallel reaction model was proposed to describe the dynamic change in catalyticactivity of ash during gasification of biomasschar particles. Three different regimes of conversion were identified by analyzing char reactivity experiments conducted in a vertical TGA with 9 biomasses under a wide range of operating conditions (temperature: 1023-1123 K, pressure: 0.1-3.0 MPa and gasification mixtures of CO2 –CO–H2O–H2): (1) catalyticchargasification with the deactivation of catalyst, (2) non-catalyticchargasification, and (3) catalyticchargasification with small amount of stable ash, without suffering deactivation. Amodel including the three regimes was developed and the measurements were used to fit the kinetic coefficients. It is shown that the model accurately predicts the reactivity of biomasschar in CO2 –CO mixtures during the whole range of conversion. It was detected that chargasification maintains the catalyticactivity during the entire conversion process when: (i) biomasses having small amount of silicon was used, and (ii) steam is used as part of the gasification agent. The model is still useful as predicting tool for these two conditions but its physical significance is contestable on the light of the model developed. For the conditions where the model is valid, it is shown that the model is a useful tool as sub-model in reactor simulations, predicting the conversion rate of single particles fast and accurately at different stages of conversion. The aspects that need to be further investigated for expanding the applicability of the model were identified.

  • 89. Umeki, Kentaro
    et al.
    Namioka, Tomoaki
    Yoshikawa, Kunio
    Analysis of an updraft biomass gasifier with high temperature steam using a numerical model2012Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 90, nr 1, s. 38-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High temperature steam gasification (HTSG) is a gasification technology which utilizes super-heated steam at a temperature above 1273 K. This paper addresses the performance analysis of an updraft HTSG gasifier using a numerical model. The experimental data obtained from a demonstration-scale gasifier was successfully simulated by the developed model. The calculation results showed 150–300 K temperature difference between gas phase and solid phase throughout the bed. Among a number of reactions, char gasification and water–gas shift reaction at char gasification zone played a major role to determine the syn-gas composition. Steam temperature, the ratio of steam to biomass and biomass feed rate affected the syn-gas composition while biomass particle diameter showed no significant effect. For the steam temperature and the ratio of steam to biomass, the difference of solid temperature at the bottom of gasifier determined the syn-gas composition. For biomass feed rate, the ratio of unreacted char extracted from the bottom of gasifier to supplied biomass determined the syn-gas composition.

  • 90.
    Umeki, Kentaro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Namioka, Tomoaki
    Tokyo Institute of Technology.
    Yoshikawa, Kunio
    Tokyo Institute of Technology.
    The effect of steam on pyrolysis and char reactions behavior during rice straw gasification2012Inngår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 94, nr 1, s. 53-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Steam gasification of biomass can generate hydrogen-rich, medium heating value gas. We investigated pyrolysis and char reaction behavior during biomass gasification in detail to clarify the effect of steam presence. Rice straw was gasified in a laboratory scale, batch-type gasification reactor. Time-series data for the yields and compositions of gas, tar and char were examined under inert and steam atmosphere at the temperature range of 873–1173 K. Obtained experimental results were categorized into those of pyrolysis stage and char reaction stage. At the pyrolysis stage, low H2, CO and aromatic tar yields were observed under steam atmosphere while total tar yield increased by steam. This result can be interpreted as the dominant, but incomplete steam reforming reactions of primary tar under steam atmosphere. During the char reaction stage, only H2 and CO2 were detected, which were originated from carbonization of char and char gasification with steam (C + H2O→CO + H2). It implies the catalytic effect of char on the water–gas shift reaction. Acceleration of char carbonization by steam was implied by faster hydrogen loss from solid residue.

  • 91. Umeki, Kentaro
    et al.
    Roh, Seon-ah
    Min, Tai-jin
    Namioka, Tomoaki
    Yoshikawa, Kunio
    A simple expression for the apparent reaction rate of large wood char gasification with steam2010Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, nr 11, s. 4187-4192Artikkel i tidsskrift (Fagfellevurdert)
  • 92. Umeki, Kentaro
    et al.
    Son, Young-il
    Namioka, Tomoaki
    Yoshikawa, Kunio
    Basic Study on Hydrogen-rich Gas Production by High Temperature Steam Gasification of Solid Wastes2009Inngår i: Journal of Environment and Engineering, ISSN 1880-988X, Vol. 4, nr 1Artikkel i tidsskrift (Fagfellevurdert)
  • 93.
    Umeki, Kentaro
    et al.
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Nagatsuta-cho 4259/G5-8, Midori-ku, 226-8502 Yokohama, Japan;Japan Society for the Promotion of Science (DC), Nagatsuta-cho 4259/G5-8, Midori-ku, 226-8502 Yokohama, Japan.
    Yamamoto, Kouichi
    The Chugoku Electric Power Co., Inc., Komachi 4-33, Naka-ku, 730-8701 Hiroshima, Japan.
    Namioka, Tomoaki
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Nagatsuta-cho 4259/G5-8, Midori-ku, 226-8502 Yokohama, Japan.
    Yoshikawa, Kunio
    Department of Environmental Science and Technology, Tokyo Institute of Technology, Nagatsuta-cho 4259/G5-8, Midori-ku, 226-8502 Yokohama, Japan;Frontier Research Centre, Tokyo Institute of Technology, Nagatsuta-cho 4259/G5-8, Midori-ku, 226-8502 Yokohama, Japan.
    High temperature steam-only gasification of woody biomass2010Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, nr 3, s. 791-798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied a high temperature steam gasification process to generate hydrogen-rich fuel gas from woody biomass. In this study, the performance of the gasification system which employs only high temperature steam exceeding 1200 K as the gasifying agent was evaluated in a 1.2 ton/day-scale demonstration plant. A numerical analysis was also carried out to analyze the experimental results. Both the steam temperature and the molar ratio of steam to carbon (S/C ratio) affected the reaction temperature which strongly affects the gasified gas composition. The H2 fraction in the produced gas was 35–55 vol.% at the outlet of the gasifier. Under the experimental conditions, S/C ratio had a significant effect on the gas composition through the dominant reaction, water–gas shift reaction. The tar concentration in the produced gas from the high temperature steam gasification process was higher than that from the oxygen-blown gasification processes. The highest cold gas efficiency was 60.4%. However, the gross cold gas efficiency was 35%, which considers the heat supplied by high temperature steam. The ideal cold gas efficiency of the whole system with heat recovery processes was 71%.

  • 94.
    Yu, Junqin
    et al.
    Institute of Clean Coal Technology, East China University of Science and Technology, 200237 Shanghai, PR China.
    Xia, Weidong
    Institute of Clean Coal Technology, East China University of Science and Technology, 200237 Shanghai, PR China.
    Areeprasertc, Chinnathan
    Department of Mechanical Engineering, Faculty of Engineering Kasetsart University 50 Ngam Wong Wan Rd., Lat Yao, Chatuchak, Bangkok 10900, Thailand.
    Ding, Lu
    Institute of Clean Coal Technology, East China University of Science and Technology, 200237 Shanghai, PR China; Shanghai Institute of Pollution Control and Ecological Security, 200092 Shanghai, PR China.
    Umeki, Kentaro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Yu, Guangsuo
    Institute of Clean Coal Technology, East China University of Science and Technology, 200237 Shanghai, PR China; State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, 750021 Yinchuan, Ningxia, PR China.
    Catalytic effects of inherent AAEM on char gasification: A mechanism study using in-situ Raman2022Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 238, part C, artikkel-id 122074Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite a small proportion of mineral in coal, inherent alkali and alkaline earth metals (AAEM) catalytically affected thermal conversion of coal. The gasification of raw and leached coal char was investigated by using an operando microscopic Raman spectroscopy to explore the effect of content and chemical form of the inherent AAEM on morphology and carbon structure evolution of a single particle during in-situ char gasification. The removal of water-soluble and ion-exchangeable AAEM reduced the R0.5 of SF, NM and YN char by 53.31%, 49.09% and 35.02%, respectively. As a result, the shrinkage of leached coal char progressed slower than that of the raw coal char. Besides, both water-soluble and ion-exchangeable AAEM accelerated char gasification because of an inhibition of the orderly evolution of carbon structure. Higher gasification temperature weakened the catalytic performance of ion-exchangeable AAEM. With the consumption of carbon, carbon microcrystalline structure of the residual char tended to be ordered, which led to a decrease in active free carbon sites for gasification reaction. Kinetic analysis indicated both water-soluble and ion-exchangeable AAEM reduced the activation energy of SF, NM and YN char by 20.97, 20.82 and 9.38kJ∙mol-1, respectively, and the effect of ion-exchangeable AAEM was more significant.

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