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  • 1.
    Ahmad, Waqar
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Benzene conversion using a partial combustion approach in a packed bed reactor2022In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 239, no Part C, article id 122251Article in journal (Refereed)
    Abstract [en]

    This study investigates the partial combustion technique for tar conversion using a modified experimental set up comprising a packed bed reactor with bed-inside probe for air supply. Simulated producer gas (SPG) and benzene were selected as a real producer gas alternative and model tar component respectively. The benzene conversion was investigated under different experimental conditions such as reactor temperature (650–900 °C), packed bed height (0–12 cm), residence time (1.2–1.9 s), air fuel ratio (0.2 and 0.3) and SPG composition. The results showed insignificant effect of temperature over benzene conversion while air fuel ratio of 0.3 caused high benzene conversion than at 0.2. Absence of packed bed lead high benzene conversion of 90% to polyaromatic hydrocarbons (PAHs) compared to similar low PAHs free benzene conversion of 32% achieved at both packed heights. In SPG composition effect, H2 and CH4 had a substantial inverse effect on benzene conversion. An increase in H2 concentration from 12 to 24 vol% increased the benzene conversion from 26 to 45% while an increase in CH4 concentration from 7 to 14 vol% reduced the benzene conversion from 28 to 4%. However, other SPG components had insignificant impacts on benzene conversion.

  • 2.
    Ahmad, Waqar
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Coke-free conversion of benzene at high temperatures2023In: Journal of the Energy Institute, ISSN 1743-9671, E-ISSN 1746-0220, Vol. 109, article id 101307Article in journal (Refereed)
    Abstract [en]

    This study investigates the conversion of benzene in a novel highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 °C. The influences of packed bed presence, reforming medium (steam and CO2), gas flow rate and benzene concentration on steady state benzene conversion are examined. In presence of packed bed, benzene conversions of 52, 75, and 84% were achieved with combined steam and CO2 reforming at 1000, 1050, and 1100 °C, respectively. Whereas, benzene conversion of 65% without the packed bed at 1000 °C experienced a continuous increase in differential upstream pressure (DUP) of high temperature (HT) filter at reactor downstream due to deposition of in situ generated coke. High concentrations of generated CO and H2 of 2.3 and 6 vol% with packed bed than 1.4 and 4.7 vol% without the packed respectively, were achieved. CO2 reforming achieved high benzene conversions of 68–98% than 42–80% achieved with stream reforming at packed bed reactor temperatures of 1000–1100 °C. The results indicated that presence of ɣ-Al2O3 packed bed with possible surface reactions directed the conversion of benzene to combustible gases instead of coke. Hence, ɣ-Al2O3 packed bed reactor could be a suitable choice for coke-free conversion of tar of gasifier producer gas.

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  • 3.
    Ahmad, Waqar
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Investigation of different configurations of alumina packed bed reactor for coke free conversion of benzene2024In: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 201, p. 433-445Article in journal (Refereed)
    Abstract [en]

    Conversion of producer gas tar without coke generation is a great challenge. This study investigates conversion of tar model benzene using different configurations of highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 0C. The configurations comprised of different positions (relative to top (P1), center (P2) and bottom (P3) of reactor furnace), heights (5, 13 and 25 cm) and particles sizes (0.5, 3 and 5 mm) of alumina packed bed. Steam and CO2 were used as reforming media for tested benzene concentrations (0.4–1.8 vol%). The results showed benzene conversions of 48–91% with negligible steady thin coke generation using a packed bed (height: 25 cm, particles size: 3 mm) at P1. Whereas, relative high benzene conversions of 63–93 and 68–95% at P2 and P3 respectively with unsteady thick coke generation at benzene concentrations greater than 0.4 vol% increased differential upstream pressures (DUPs) of beds. Similar unsteady coke generation at benzene concentrations greater than 0.8 vol% and temperature of 1100 0C was observed with packed beds of heights of 5 and 13 cm, and particles size of 0.5 mm at P1. Generation of unsteady coke with condensed structure as evidenced by its characterization was attributable to increased benzene polymerization and reduced bed surface gasification reactions due to improperly installed packed bed. Developed kinetic model predicted well the generated coke. As conclusion, properly installed alumina packed bed pertaining to tar concentration and other experimental conditions may inhibit coke generation during tar conversion.

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  • 4.
    Asuquo, Asuquo Jackson
    et al.
    University of Strathclyde, UK.
    Zhang, Xiaolei
    University of Strathclyde, UK.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Li, Jun
    University of Strathclyde, UK.
    Green heterogeneous catalysts derived from fermented kola nut pod husk for sustainable biodiesel production2024In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083Article in journal (Refereed)
    Abstract [en]

    The use of green heterogeneous catalysts that are obtained from waste agricultural biomass can make the production of biodiesel more economical. In this research, three solid base heterogeneous catalysts (Catalyst A, B, and C) were synthesized from kola nut pod husks, and the synergistic effects of the elemental composition on catalytic activities for biodiesel production were studied. The results revealed a high surface area of Catalysts A, B, and C at 419.90 m2/g, 430.54 m2/g, and 432.57 m2/g, respectively. Their corresponding pore diameters are 3.53 nm, 3.48 nm, and 3.32 nm, showing that the catalysts are mesoporous in nature. The X-ray Fluorescence (XRF) results revealed the presence of a variety of alkaline earth metals and their corresponding metal oxides in substantial amounts. Catalyst A was produced with the highest concentration of calcium at 40.84 wt.% and calcium oxide at 68.02 mole%. The substantial concentration of other elements, such as potassium, magnesium, and aluminum, and their corresponding metal oxides are the proof of high catalytic activity of the produced green catalysts. The high CaO contents of all three produced catalysts and their high surface areas indicate their strong potential for good catalytic activities applied to the synthesis of biodiesel.

  • 5.
    Biollaz, S.
    et al.
    PSI.
    Calbry-Muzyka, A.
    PSI.
    Rodriguez, S.
    PSI.
    Sárossy, Z.
    DTU.
    Ravenni, G.
    DTU.
    Fateev, A.
    DTU.
    Seiser, R.
    UCSD.
    Eberhard, M.
    KIT.
    Kolb, T.
    KIT.
    Heikkinen, N.
    VTT.
    Reinikainen, M.
    VTT.
    Brown, R.C.
    Iowa State University, USA.
    Johnston, P.A.
    Iowa State University, USA.
    Nau, P.
    DLR.
    Geigle, K.P.
    DLR.
    Kutne, P.
    DLR.
    Işık-Gülsaç, I.
    TÜBİTAK Mam.
    Aksoy, P.
    TÜBİTAK Mam.
    Çetin, Y.
    TÜBİTAK Mam.
    Sarıoğlan, A.
    TÜBİTAK Mam.
    Tsekos, C.
    Delft University of Technology, Netherlands.
    de Jong, W.
    Delft University of Technology, Netherlands.
    Benedikt, F.
    TU Wien, Austria.
    Hofbauer, H.
    TU Wien, Austria.
    Waldheim, L.
    SFC.
    Engvall, K.
    KTH Royal instute of technology, Sweden.
    Neubauer, Y.
    Technical University of Berlin, Germany.
    Funcia, I.
    CENER.
    Gil, J.
    CENER.
    del Campo, I.
    CENER.
    Wilson, I.
    University of Glasgow, UK.
    Khan, Z.
    University of Glasgow, UK.
    Gall, D.
    University of Gothenburg, Sweden.
    Gómez-Barea, A.
    University of Seville, Spain.
    Schmidt, F.
    Umeå University, Sweden.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Anca-Couce, A.
    Graz University of Technology, Austria.
    von Berg, L.
    Graz University of Technology, Austria.
    Larsson, A.
    GoBiGas.
    Sánchez Hervás, J.M.
    CIEMAT.
    van Egmond, B.F.
    ECN part of TNO.
    Geusebroek, M.
    ECN part of TNO.
    Toonen, A.
    ECN part of TNO.
    Kuipers, J.
    ECN part of TNO.
    Cieplik, M.
    ECN part of TNO.
    Boymans, E.H.
    ECN part of TNO.
    Grootjes, A.J.
    ECN part of TNO.
    Fischer, F.
    TUM.
    Schmid, M.
    University of Stuttgart, Germany.
    Maric, J.
    Chalmers University of Technology, Sweden.
    Defoort, F.
    CEA.
    Ravel, S.
    CEA.
    Thiery, S.
    CEA.
    Balland, M.
    CEA.
    Kienzl, N.
    Bioenergy 2020+.
    Martini, S.
    Bioenergy 2020+.
    Loipersböck, J.
    Bioenergy 2020+.
    Basset, E.
    ENGIE Lab CRIGEN.
    Barba, A.
    ENGIE Lab CRIGEN.
    Willeboer, W.
    RWE-Essent.
    Venderbosch, R.
    BTG.
    Carpenter, D.
    NREL.
    Pinto, F.
    LNEG.
    Barisano, D.
    ENEA.
    Baratieri, M.
    UNIBZ.
    Ballesteros, R.
    UCLM.
    Mourao Vilela, C. (Editor)
    ECN part of TNO.
    Vreugdenhil, B.J. (Editor)
    ECN part of TNO.
    Gas analysis in gasification of biomass and waste: Guideline report: Document 12018Report (Refereed)
    Abstract [en]

    Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). In practice, a trade-off between reliability, accuracy and cost has to be reached when selecting the proper analysis technique for a specific application. The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.

    This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to(biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. The report is composed of a set of 2 documents. Document 1(the present report) describes the available analysis techniques (both commercial and underdevelopment) for the measurement of different compounds of interest present in gasification gas. The objective is to help the reader to properly select the analysis technique most suitable to the target compounds and the intended application. Document 1 also describes some examples of application of gas analysis at commercial-, pilot- and research gasification plants, as well as examples of recent and current joint research activities in the field. The information contained in Document 1 is complemented with a book of factsheets on gas analysis techniques in Document 2, and a collection of video blogs which illustrate some of the analysis techniques described in Documents 1 and 2.

    This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.

  • 6.
    Biollaz, S.
    et al.
    PSI.
    Calbry-Muzyka, A.
    PSI.
    Rodriguez, S.
    PSI.
    Sárossy, Z.
    DTU.
    Ravenni, G.
    DTU.
    Fateev, A.
    DTU.
    Seiser, R.
    UCSD.
    Eberhard, M.
    KIT.
    Kolb, T.
    KIT.
    Heikkinen, N.
    VTT.
    Reinikainen, M.
    VTT.
    Brown, R.C.
    Iowa State University, USA.
    Johnston, P.A.
    Iowa State University, USA.
    Nau, P.
    DLR.
    Geigle, K.P.
    DLR.
    Kutne, P.
    DLR.
    Işık-Gülsaç, I.
    TÜBİTAK Mam.
    Aksoy, P.
    TÜBİTAK Mam.
    Çetin, Y.
    TÜBİTAK Mam.
    Sarıoğlan, A.
    TÜBİTAK Mam.
    Tsekos, C.
    Delft University of Technology, Netherlands.
    de Jong, W.
    Delft University of Technology, Netherlands.
    Benedikt, F.
    TU Wien, Austria.
    Hofbauer, H.
    TU Wien, Austria.
    Waldheim, L.
    SFC.
    Engvall, K.
    KTH Royal instute of technology, Sweden.
    Neubauer, Y.
    Technical University of Berlin, Germany.
    Funcia, I.
    CENER.
    Gil, J.
    CENER.
    del Campo, I.
    CENER.
    Wilson, I.
    University of Glasgow, UK.
    Khan, Z.
    University of Glasgow, UK.
    Gall, D.
    Gothenburg University, Sweden.
    Gómez-Barea, A.
    University of Seville, Spain.
    Schmidt, F.
    Umeå University, Sweden.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Anca-Couce, A.
    Graz University of Technology, Austria.
    von Berg, L.
    Graz University of Technology, Austria.
    Larsson, A.
    GoBiGas.
    Sánchez Hervás, J.M.
    CIEMAT.
    van Egmond, B.F.
    ECN part of TNO.
    Geusebroek, M.
    ECN part of TNO.
    Toonen, A.
    ECN part of TNO.
    Kuipers, J.
    ECN part of TNO.
    Cieplik, M.
    ECN part of TNO.
    Boymans, E.H.
    ECN part of TNO.
    Grootjes, A.J.
    ECN part of TNO.
    Fischer, F.
    TUM.
    Schmid, M.
    University of Stuttgart, Germany.
    Maric, J.
    Chalmers University of Technology, Sweden.
    Defoort, F.
    CEA.
    Ravel, S.
    CEA.
    Thiery, S.
    CEA.
    Balland, M.
    CEA.
    Kienzl, N.
    Bioenergy 2020+.
    Martini, S.
    Bioenergy 2020+.
    Loipersböck, J.
    Bioenergy 2020+.
    Basset, E.
    ENGIE Lab CRIGEN.
    Barba, A.
    ENGIE Lab CRIGEN.
    Willeboer, W.
    RWE-Essent.
    Venderbosch, R.
    BTG.
    Carpenter, D.
    NREL.
    Pinto, F.
    LNEG.
    Barisano, D.
    ENEA.
    Baratieri, M.
    UNIBZ.
    Ballesteros, R.
    UCLM.
    Mourao Vilela, C. (Editor)
    ECN part of TNO.
    Vreugdenhil, B.J. (Editor)
    ECN part of TNO.
    Gas analysis in gasification of biomass and waste: Guideline report: Document 2 - Factsheets on gas analysis techniques2018Report (Refereed)
    Abstract [en]

    Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.

    This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to (biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.

  • 7.
    Cao, Wenhan
    et al.
    University of Strathclyde, UK.
    Li, Jun
    University of Strathclyde, UK.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Zhang, Xiaolei
    University of Strathclyde, UK.
    Release of potassium in association with structural evolution during biomass combustion2021In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 287, p. 1-9, article id 119524Article in journal (Refereed)
    Abstract [en]

    A mechanistic understanding of potassium release is essential to mitigate the potassium-induced ash problems during biomass combustion. This work studies the effects of operational condition on the potassium release and transition during the combustion of wheat straw, and elucidate the release potential of potassium associated with the structural change of biomass particles. The combustion tests were carried out in a laboratory-scale reactor, working in a wide range of temperatures and heating rates. It was found that the combustion of biomass sample at a temperature up to 1000 °C results in a release of over 60% of its initial potassium content. Raising the heating rate from 8 °C/min to 25 °C/min could lead to an additional release of up to 20% of the initial amount of potassium. A three-stage potassium release mechanism has been concluded from this work: the initial-step release stage (below 400 °C), the holding stage (400–700 °C) and the second-step release stage (above 700 °C). Comprehensive morphology analysis with elemental (i.e. K, S, O, Si) distribution was carried out; the results further confirmed that potassium is likely to exist inside the stem-like tunnel of biomass particles, mainly in forms of inorganic salts. During the heating-up process, the breakdown and collapse of biomass particle structure could expose the internally located potassium and thus accelerate the release of potassium and the transform of its existing forms. Lastly, a detailed temperature-dependent release mechanism of potassium was proposed, which could be used as the guidance to mitigate the release of detrimental potassium compounds by optimising the combustion process.

  • 8.
    Fu, Dianliang
    et al.
    Shandong University, China.
    Truong, Nguyen Le
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lai, Yanhua
    Shandong University, China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Dong, Zhen
    Shandong University, China.
    Lyu, Mingxin
    Shandong University, China.
    Improved pinch-based method to calculate the capital cost target of heat exchanger network via evolving the spaghetti structure towards low-cost matching2022In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 343, article id 131022Article in journal (Refereed)
    Abstract [en]

    Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.

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  • 9.
    Fu, Jiapeng
    et al.
    Shandong University, China.
    Liu, Zhuhan
    Xi'an Jiaotong University, China.
    Wei, Lin
    Xi'an Jiaotong University, China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Li, Na
    Xi'an Jiaotong University, China.
    Zhou, Qulan
    Xi'an Jiaotong University, China.
    Ma, Chunyuan
    Shandong University, China.
    Identification of the running status of membrane walls in an opposed fired model boiler under varying heating loads2020In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 173, p. 1-9, article id 115217Article in journal (Refereed)
    Abstract [en]

    To understand the running status of membrane walls in an opposite firing boiler, a scale-down model furnace was established, and the temperature, heat flux, strain and stress distributions are investigated under four heating loads. Results show that the average membrane wall temperature and heat flux present a continuous increase from 42 oC and 16 W/m2 to 96 oC and 50 W/m2, respectively, with the heating load increase from 25% to full load. The average strain and stress also rise from 88.7 µm and 0.094 MPa to 152.5 µm and 0.148 MPa when the heating load increases from 25% to 50%, but then they keep stable when further increasing the heating load. General distribution patterns of each tested parameter are found relatively similar under varying heating loads. High strain and stress distributions are always detected at the middle left zone of side walls and the middle of the rear wall, where wall temperatures are measured high. External fixed constraints and high-temperature thermal strain is found jointly affecting the strain and stress distribution of the membrane wall. A simplified mechanism of how the strain and stress on boiler membrane walls evolve is proposed after comprehensive discussion of the measurement results.

  • 10.
    Fu, Jiapeng
    et al.
    Shandong University, China.
    Zhou, Binxuan
    Shandong University, China.
    Zhang, Zhen
    North China University of Water Resources and Electric Power, China.
    Wang, Tao
    Shandong University, China.
    Cheng, Xingxing
    Shandong University, China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Ma, Chunyuan
    Shandong University, China.
    One-step rapid pyrolysis activation method to prepare nanostructured activated coke powder2020In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 262, article id 116514Article in journal (Refereed)
    Abstract [en]

    A one-step rapid pyrolysis activation method is proposed to produce activated coke powder (ACP) via a drop tube reactor by using pulverized Datong coal (DTC) and pine wood (PW) as feedstock. Small feedstock particle size, high heating rate, and effective activation agent, i.e., the mixture of oxygen and steam were arranged for the fast formation and development of various pore structure of ACPs. Detail characteristics of the ACP were investigated by using the nitrogen adsorption measurement, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) analysis. Results showed that the ACP presented well-developed nanostructure with considerable pore volume, specific surface area and surface functional groups. The pore volume and specific surface area of PWC-O6S10 could reach 0.2373 cm3/g and 250.57 m2/g. Activation atmosphere had played an important role to develop the pore structure and morphology of the ACP. Under 6 vol% oxygen concentration, the optimum steam partial pressure for micropore development of DTC was about 15 vol%, while it mostly promoted the growth of mesopores for PWC. All ACP samples presented variety of C/O/N containing surface functional groups, including OH, CH, CC, CO, CO, COC, CN, CN, etc., which remained relatively stable as the activation agents concentration changed.

  • 11.
    Gustafsson, Eva
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Seemann, Martin C.
    Rodin, Jennie
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Characterization of Particulate Matter in the Hot Product Gas from Indirect Steam Bubbling Fluidized Bed Gasification of Wood Pellets2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, no 4, p. 1781-1789Article in journal (Refereed)
    Abstract [en]

    This study characterized the particulate matter (PM) formed during the indirect steam bubbling fluidized bed gasification of wood pellets at atmospheric pressure. A system including a dilution probe, a bed of granular activated carbon, and a thermodenuder was used to sample the PM at high temperature with the aim of separating it from condensing inorganic vapors and tars. The particle mass size distribution was bimodal with a fine mode in the <0.5-μm size range and a dominating coarse mode in the >0.5-μm size range. The coarse mode was representatively characterized while condensing inorganic vapors and tars complicated the evaluation of the results for the fine-mode PM. Morphological analysis of the PM indicated that the char content was low. The inorganic fraction was dominated by potassium and chlorine for fine-mode PM and calcium and silicon for coarse-mode PM.

  • 12.
    Gustafsson, Eva
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Characteristics of aerosol particles from steam and oxygen gasification of various biofuels2010In: 18th European Biomass Conference and Exhibition: From resarch to industry and markets, ETA Renewable Energies and WIP Renewable Energies , 2010, p. 900-902Conference paper (Refereed)
    Abstract [en]

    The present study investigated how the characteristics of the particulate matter (PM) from steam and oxygen gasification of biomass were affected by the biofuel used. The results show that the biofuel had a large impact on the fine mode PM generated during the gasification, both on the particle size distribution and on the elementary composition. When using miscanthus as fuel, high concentrations of ultrafine particles consisting of potassium chloride were formed compared to when using high- and low-quality wood (wood A and wood B) as fuels. The impact of the biofuel on the coarse mode PM was less in this study. Large amounts of bed material dominated the coarse fraction. However, heavy metals were detected in the coarse mode PM when using wood B, constituting treated wood, as fuel.

  • 13.
    Gustafsson, Eva
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Characterization of Particulate Matter from a Circulating Fluidized Bed Gasifier Using Different Types of BiomassManuscript (preprint) (Other academic)
    Abstract [en]

    This study characterized the particulate matter (PM) formed during gasification of different types of biomass in a circulating fluidized bed gasifier at atmospheric pressure. Two systems were used to sample the PM, and both on- and offline analysis techniques were used to characterize the PM. Four different instruments were used to measure the particle mass size distribution and concentration in the size range 0.01–30 µm. The agreement between the instruments was good, and the particle mass size distributions upstream of any cleaning device were bimodal, dominated by the coarse mode (>0.5 µm). The particle mass concentration of the fine mode (<0.5 µm) varied, depending on which biomass was used. The variation in particle mass concentration of the coarse mode was less, and was due to different loads of bed material and various ash contents in the biomass. The morphological analysis of the PM showed that the char content was low and that the PM was dominated by ash and bed material. The coarse-mode PM was rich in magnesium and calcium, while potassium and chlorine were prevalent in the fine-mode PM. The elementary composition of the PM varied between the different types of biomass used and heavy metals, that is, zinc and lead, were detected in low concentrations when using demolition wood as fuel.

  • 14.
    Gustafsson, Eva
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Characterization of particulate matter in the hot product gas from atmospheric fluidized bed biomass gasifiers2011In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 35, no Supplement 1, p. 71-78Article in journal (Refereed)
    Abstract [en]

    This study compares the characteristics of particulate matter (PM) in the hot product gas from three different atmospheric fluidized bed biomass gasifiers: a bubbling fluidized bed (BFB) gasifier, a circulating fluidized bed (CFB) gasifier, and an indirect BFB gasifier (the latter integrated with a CFB boiler). All gasifiers displayed a bimodal particle mass size distribution with a fine mode in the <0.5 μm size range and a coarse mode in the >0.5 μm size range. Compared with the mass concentration of the coarse mode the mass concentration of the fine mode was low in all gasifiers. For both the BFB and CFB gasifiers the fine-mode PM had a similar inorganic composition, indicating an origin from the ash and the magnesite bed material used in both gasifiers. In the indirect BFB gasifier the fine-mode PM was instead dominated by potassium and chlorine, and the tar fraction properties evoked tar condensation in the sampling system that affected mainly the fine-mode PM. The coarse-mode PM in the BFB gasifier was dominated by char fragments abraded from the pyrolyzed wood pellets. In the CFB gasifier the coarse-mode PM was mainly ash and magnesite bed material that passed through the process cyclone. In the indirect BFB gasifier the coarse-mode PM was mainly ash, probably originating both from the BFB gasifier and the CFB boiler.

  • 15.
    Gustafsson, Eva
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Simeone, Eleonora
    Technical University of Delft.
    de Jong, Wiebren
    Technical University of Delft.
    Müller, Michael
    Forschungszentrum Jülich.
    Porbatzki, Dirk
    Forschungszentrum Jülich.
    Report of Particle Size and Composition Classificationduring Atmospheric Pressure Gasification2010Report (Other academic)
  • 16.
    Jiang, Junfei
    et al.
    Chinese Academy of Sciences (CAS), China.
    Lang, Lin
    Chinese Academy of Sciences (CAS), China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Liu, Huacai
    Chinese Academy of Sciences (CAS), China.
    Yin, Xiuli
    Chinese Academy of Sciences (CAS), China.
    Wu, Chuang-zhi
    Chinese Academy of Sciences (CAS), China.
    Partial oxidation of filter cake particles from biomass gasification process in the simulated product gas environment2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 2, p. 1703-1710Article in journal (Refereed)
    Abstract [en]

    Filtration failure occurs when filter media is blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCP) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermo-gravimetric analysis through a temperature-programmed route in a 2 vol.% O2–N2 environment. Partial oxidation of the FCP in the simulated product gas environment was examined at 300–600°C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely drying, pre-oxidation, complex oxidation and non-oxidation, occurred in the FCP partial oxidation when the temperature increased from 30°C to 800°C in a 2 vol.% O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725°C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400°C and 1.59 g/cm2, respectively. The FCP were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy and Brunaeur–Emmett–Teller before and after partial oxidation. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCP can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C=O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analysis suggests that during partial oxidation, the FCP underwent pore or pit formation, expansion, amalgamation and destruction.

  • 17.
    Johansson, Wanja
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Li, Jun
    University of Strathclyde, UK.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Module-based simulation model for prediction of convective and condensational heat recovery in a centrifugal wet scrubber2023In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 219, article id 119454Article in journal (Refereed)
    Abstract [en]

    Biomass combustion is a carbon–neutral method to generate heat and power and is integral to combating climate change. The wet scrubber is a promising device for recovering heat and reducing particle emissions from flue gas, under the driving force of new European Union legislation. Here, the heat recovery of a wet scrubber was investigated using process data and computer simulations. The process data showed that the scrubber could continuously recover heat corresponding to 10–20% of the energy input. The simulation model consists of two interlinked modules: Module 1 simulates droplet movement in the scrubber, while Module 2 uses the output of Module 1 to predict the heat recovery. The model was validated against process data, showing a mean error of 5.6%. Further optimization was based on the validated model by varying different process parameters, including nozzle position and moisture addition to the flue gas. Moisture addition was shown to be a feasible strategy for potentially increasing heat recovery by up to 3.3%. These results indicate that heat recovery in wet scrubbers is a feasible way to make particle removal cost effective in medium-scale combustion facilities, and that the developed simulation model can play an important role in optimizing these processes.

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  • 18.
    Johansson, Wanja
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Full year assessment of small-scale biomass-fueled district heating system with waste heat recovery2022In: European Biomass Conference and Exhibition Proceedings / [ed] Chevet P.-F., Scarlat N., Grassi A., ETA-Florence Renewable Energies , 2022, p. 696-698Conference paper (Refereed)
    Abstract [en]

    The use of biomass for district heating is a carbon neutral and efficient way to heat buildings. To ensure a sustainable use of the biomass, it is important to ensure a high thermal efficiency not only in combustion facilities of all sizes. In this paper, the thermal efficiency of a 3 MW combustion unit with recovery of waste flue gas energy has been evaluated, using process data from a full year. A decreased efficiency is observed at boiler loads below 1 MW, while the efficiency is more stable at higher load. The furnace and boiler efficiency are stable over different moisture contents of the fuel, while the efficiency including heat recovery is greatly enhanced at high moisture content. High return water temperature was linked to a decreased efficiency of the whole system due to decreased efficiency of the heat recovery unit.

  • 19.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Char conversion kinetics and aerosol characterization in biomass gasification2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biomass gasification is a thermochemical conversion by partial oxidation at elevated temperature of solid biomass into a gaseous energy carrier. The product gas contains the major components CO, H2, CO2, CH4, as well as some tar and inorganic impurities and solid particles such as ash, bed material, soot and char. The aim of this work is to develop an aerosol-based method to investigate on-line the reactivity of the suspended biomass char particles at high temperatures, and to apply aerosol measurement systems for sampling and characterizing particulate matter in the hot product gas from gasifiers.

    An aerosol-based method including the steps for generating, transporting, and oxidizing suspended char particles (0.5–10 µm) was proposed and developed for investigation of char reactivity at high temperatures. An aerodynamic particle sizer (APS) spectrometer was used to measure the particle size distributions. A tapered element oscillating microbalance (TEOM) was used to measure the change of mass concentrations of particles in the carrier gas, before and after conversion. The intrinsic kinetics of various biomass (wood, straw, miscanthus) char particles have been experimentally established in a wide temperature range for both combustion (in air/oxygen) and gasification (in 33 vol% CO2 or 33 vol% steam), up to 800°C and 1300°C, respectively, by combining the aerosol method with thermogravimetric analysis (TGA). The general CO2 or steam gasification reactivity of chars from different biomass could be ranked as wood > miscanthus > straw. In CO2 or steam gasification, the reactivity of char samples measured by the aerosol method at 1300°C would vary by a factor of 4-9 comparing with the extrapolated estimation from the TGA results at the low temperatures. This indicates that high-temperature reactivity estimation by extrapolation should be used with care. Variations of the morphology and the effective density of char particles during conversion indicated that in the initial stage of char conversion (either combustion or gasification), pore growth was dominant up to a certain conversion, and shrinkage or fusing would occur in the later stage. The aerosol-based method presents a set of benefits which are advantageous compared to previously established techniques: no mass transfer limitation at high temperatures; the flexibility to switch to different gas agent combined with continuous feeding of char sample; and the on-line measurement of particle mass and size. The aerosol method is not applicable under the conditions where the reaction rate is slow, since longer residence time will increase the probability of particle losses. In addition to laboratory applications, the aerosol method has potentials for on-line investigation of concentration and reactivity of suspended char fragments sampled directly from the product gas in different types of gasifiers.

    Particulate matter (10 nm–10 µm) in the product gas was characterized for the size distribution, morphology and elemental composition by both on-line and off-line techniques. An aerosol particle measurement system including a dilution probe connected in series with a packed activated carbon bed was applied to extract aerosol from the hot product gas produced in the gasifiers using wood as feedstock: an indirect bubbling fluidized bed gasifier and a circulating fluidized bed (CFB) gasifier. The fine and coarse particles from the CFB gasifier contained calcium and magnesium, indicating the contributions from the ash and the magnesite bed material. From the indirect gasifier, the fine-mode (<0.5 µm) particles were dominated by potassium and chlorine whereas the coarse-mode (>0.5 µm) particles were dominated by calcium and silicon, probably from the ash and the bed material. Char fragments were identified in the hot product gas and contribute to the coarse-mode particles in both gasifiers.

     

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  • 20.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Eva
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Aerosol-based method for investigating biomass char reactivity at high temperatures2011In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 158, no 7, p. 1426-1437Article in journal (Refereed)
    Abstract [en]

    An aerosol-based method was proposed and developed to characterize particles fragmented from biomass chars during oxidation. The chars were prepared from both wood and miscanthus pellets under various pyrolysis conditions. Char fragments with aerodynamic diameters in the range of 0.5–10 μm were suspended and transported in a reactive gas through an aerosol reactor, which was heated by an electric oven. The oxidation of char particles in the reactor was investigated by determining on-line the particle size distributions before and after passage through the reactor using an aerodynamic particle sizer (APS) spectrometer. The interpretation of APS data was evaluated by both experiments and models in which the fine char particles were assumed to keep either constant density or constant diameter during the oxidation process. The results indicate that the aerosol-based method can be used to determine reaction kinetics of char particles in the high temperature range, where oxidation is normally controlled by diffusion limitation if measuring with the conventional techniques. The application of the aerosol method indicated that high pyrolysis temperature and prolonged retention time will reduce the char reactivity.

  • 21.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Eva
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    High-temperature Kinetics of Fine Biomass Char Particles in Air and CO22010In: 18th European Biomass Conference and Exhibition: From Research to Industry and Markets, 2010Conference paper (Refereed)
    Abstract [en]

    Knowledge of reliable chemical kinetics of char always plays significant roles in the modelling, design and optimization of processes during biofuel thermochemical conversions.The determination of reaction kinetics of char in the high-temperature range still highly depends on the extrapolation of results from kinetic data determined at lower temperatures due to mass and heat transfer limitations. In this work an aerosol-based method was used to investigate the reactivity of singly-distributed char particles with aerodynamic diameters between 0.5-10 mm. The conversion of char particles in the reactor at varying temperatures and residence time was determined by comparing the particle size distributions before and after passing the reactor, using an aerodynamic particle sizer (APS) spectrometer. The results of char particles reacted with air, CO2 and steam indicate that the aerosol-based method can be used to determine reaction kinetics of char particles in the high temperature range where reaction is controlled by diffusion limitation if using conventional thermogravimetric analysis (TGA). By combining the aerosol-based method and conventional TGA, the oxidation and gasification kinetic parameters of biomass char can be derived in the temperature range of 350-800ºC, and 800-1200ºC respectively. The aerosol-based method shows the potential of on-line measuring the char reactivity.

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  • 22.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Morgalla, Mario
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Study on char fragmentation during biomass gasification in bubbling fluidized bed2015In: 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, ETA-Florence Renewable Energies , 2015, p. 652-655Conference paper (Refereed)
    Abstract [en]

    In this work a bench scale bubbling fluidized bed gasifier was built to work with an aerosol sampling and measuring system in order to study char fragmentation phenomenon during biomass gasification process. Both barbeque char and wood pellets were gasified in CO2 (20 vol.%) -N2 mixture and steam (30 vol.%)-N2 mixture, respectively. An aerodynamic particle sizer (APS) was used to measure fragmented char particles during the whole gasification process. For the wood pellet gasification case, major fragmentation was observed during the devolatilization stage, which should be attributed to the combined effect of primary fragmentation and attrition. The aerodynamic diameter of those elutriable particles which can be measured by the current system was in the range of 0.5-8 µm. During the char gasification stage, a distinct mode of char fragments was produced in the size range of 1-7 µm in either case. The total mass concentration of elutriable particles gradually increased when gasification of char started, and then decreased while the reaction approached completion.

  • 23.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Further development and application of aerosol-based method for on-line investigation of char reactivity in steam2013In: Proceedings for 21st European Biomass Conference and Exhibition, ETA-Florence Renewable Energies , 2013, p. 875-878Conference paper (Refereed)
    Abstract [en]

    Wood char was prepared from wood pellets under controlled pyrolysis conditions. The gasification kinetics for wood char in 33 vol% steam was established in the temperature range from 800ºC to 1300ºC by the combination of thermogravimetric analysis (TGA) and a novel aerosol-based method. The aerosol method was further developed and demonstrated successfully for generating, transporting and gasifying the suspended char particles (0.5-10 µm) in the steam atmosphere at high temperature up to 1300ºC. A tapered element oscillating microbalance (TEOM) was used to measure the change of mass concentrations of particles in the carrier gas, before and after gasification. The activation energy was 155 kJ·mol-1 for wood char with the pre-exponential factor of 3.56×104. This method can be potentially applied to on-line measure the reactivity of char particles directly in hot gas from the gasifier.

  • 24.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Investigation of the intrinsic CO2 gasification kinetics of biomass char at medium to high temperatures2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 109, no SI, p. 220-228Article in journal (Refereed)
    Abstract [en]

    In total eight char samples from pelletized wood, miscanthus, and straw were prepared under various pyrolysis conditions. The CO2 gasification kinetics for each sample was established in the temperature range from 800 °C to 1300 °C by the combination of thermogravimetric analysis (TGA) and a novel aerosol-based method. The aerosol-based method was used for the high temperature range between 1100 °C and 1300 °C, by gasifying suspended char particles (0.5–10 μm) in an oxidizing carrier gas. A tapered element oscillating microbalance (TEOM) was used to measure the change of mass concentrations of particles in the carrier gas, before and after gasification. The results showed that the aerosol-based method could be used to investigate the intrinsic gasification kinetics of biomass char, at least up to 1300 °C. All char samples showed similar reactivity in the low temperature range. However, above 1000 °C there were significant differences in reactivity, and at 1300 °C the conversion of the wood was in the order of 10 times faster than that of straw. The general char reactivity order in this study was wood > miscanthus > straw.

  • 25.
    Lin, Leteng
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Strand, Michael
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Investigation on the oxidation kinetics of biomass char particles2009In: Book of Proceeding-Bioenergy 2009: Sustainable Bioenergy Business 4th International Bioenergy Conference / [ed] Mia Savolainen, Jyväskylä: FINBIO , 2009, p. 933-939Conference paper (Refereed)
    Abstract [en]

    One specific type of wood pellets were pyrolyzed with both low and high heating rate in nitrogen atmosphere at 800-900°C. The pulverized chars were oxidized by thermo gravimetric analysis (TGA) in an atmosphere of nitrogen with 3%-21% of oxygen admixture. Three pore models reported in the literature were tested against the experimental data. In order to investigate the reactivity of singly distributed particles, char samples were fragmented and suspended into a gas using a shaking device. A fraction of suspended particles with an aerodynamic diameter between 0.5-10 um were then fed into a tubular reactor heated by an electric oven. The oxidation of char particles in the reactor at different temperatures was investigated by measuring the particle size distribution before and after passing the reactor, using an aerodynamic particle sizer (APS) spectrometer. This method made it possible to investigate the oxidation kinetics of char particles at high temperature area which is hard to realize in TGA due to the mass transportation limitation.

  • 26.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Online investigation of steam gasification kinetics of biomass chars up to high temperatures2014In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, no 1, p. 607-613Article in journal (Refereed)
    Abstract [en]

    In this study, a novel aerosol-based method has been further developed and applied for on-line investigating of steam gasification kinetics of suspended biomass char particles. By combining the aerosol method with thermogravimetric analysis, the gasification kinetics were established in steam (33 vol%)-N2 atmosphere from 800°C to 1300°C for char samples produced from pelletized wood, straw, and miscanthus. The aerosol method includes steps for generating, suspending, and gasifying char particles. The conversion of the char particles was established by measuring the change in particle size distributions and mass concentrations using an aerodynamic particle sizer (APS) spectrometer and a tapered element oscillating microbalance (TEOM), respectively. The reactivity of three char samples could be ranked as wood > miscanthus > straw. The activation energy was 155 kJ·mol-1 for wood char, 199 kJ·mol-1 for miscanthus char, and 222 kJ·mol-1 for straw char. Results interpreted from TEOM and APS measurements indicated that the effective density of char particles initially decreased until a certain level of conversion was reached, and then remained constant. 

  • 27.
    Lin, Leteng
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Zethraeus, Björn
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    An Extractive Numerical Method to Interpret Gas Analysis from Domestic Scale Pellets Burner2009In: Book of proceedings-Bioenergy 2009: Sustainable Bioenergy Business4th International Bioenergy Conference / [ed] Mia Savolainen, Jyväskylä: FINBIO publication 45 , 2009, p. 517-523Conference paper (Refereed)
    Abstract [en]

    The mathematical background to the gas analysis problem is that the measurement system introduces a time constant into the gas analysis values. This time constant is not only a simple delay of the signal but also involve a damping of the amplitudes in the signal. Therefore, the registered values by measurement system can be treated as the convolution between the system response and the real gas analysis values. In this paper the plug flow with an overlaid axial diffusion was introduced to simulate the delay and damping effects of gas measurement system. The numerical method developed here is to extract the real gas values from the measured data in the de-convolution way to find what the reality is behind the registered values. All registered data were collected by two different gas analysis systems for measuring the gas out of a pellets burner – Velmax (Finnish brand). This numerical method is meaningful to get closer to the reality of measured data which is definitely needed step for the improvement of controlling the small scale combustion even though it still can be developed further.

  • 28.
    Lin, Leteng
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Zethraeus, Björn
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Statistical model to reproduce the combustion behavior of domestic-scale wood pellets burners2016In: Proceedings of the 24th European Biomass Conference: Setting the course for a biobased economy, ETA-Florence Renewable Energies , 2016, p. 666-673Conference paper (Refereed)
    Abstract [en]

    A simplified statistical model was developed to simulate the combustion behavior in wood pellets burners based on the eddy dissipation concept and the assumption that the turbulence to some extents can be treated in a similar way in both the larger scales and the smaller scales. The combustion system was divided into several macroscopic sub-volumes which were characterized by plug flow function with axial diffusion that helps to bridge the geometry with the mixing status and describe the dissipation of turbulence by means of digital filter. Initially a time series of fuel-air mixture was defined according to feedstock and air supply in burner and then successively modified in the following sub-volumes based on the predefined function and additional air. With favor of mass and energy balance the final gas composition can be approximately distributed by water gas equilibrium. After involved the system response of gas analysis instrumentation, the modelled results were compared with experimental tests in two commercialized types of pellet burners, named gasification type and combustion type respectively. The model predicted reasonably the over-all behavior of domestic-scale pellet burners on the mean value and standard deviation of gas compositions, especially the behavior of CO2 and O2 in both cases. The CO emission was simulated unstably but within an acceptable range. This model can be used as an on-line predictor in combustion control systems and may thus serve as a tool for fast-response combustion control. 

  • 29.
    Morgalla, Mario
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Seemann, Martin
    Chalmers University of Technology, Sweden.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Characterization of particulate matter formed during wood pellet gasification in an indirect bubbling fluidized bed gasifier using aerosol measurement techniques2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, p. 578-587Article in journal (Refereed)
    Abstract [en]

    This study characterizes particulate matter, organic compounds, and inorganic compounds formed in an atmospheric indirect bubbling fluidized bed gasifier at two different steam-to-fuel ratios using wood pellets as fuel. The sampling and conditioning system consisted of a high-temperature dilution probe to quench aerosol dynamics and condense inorganic vapors, a primary thermodenuder to adsorb tar components, and a secondary thermodenuder to investigate the volatility/thermal stability of the remaining aerosol. Both online and offline instruments were used to characterize the aerosol in terms of number size distribution, mass size distribution, particle mass concentration, particle number concentration, morphology, and elemental analysis. Size distributions with three distinct modes were established. The fine and intermediate modes were mainly formed by tar and alkali vapors that had condensed in the sampling and conditioning systems. The coarse mode mainly consisted of the original particles, which are char, fly ash, and fragmented bed material. At the higher steam-to-fuel ratio, tar components seem to be reduced and more coarse-mode particles emitted compared to the low steam case. Furthermore, a possibility for online monitoring of heavy tar is suggested. (C) 2015 Elsevier B.V. All rights reserved.

  • 30.
    Morgalla, Mario
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Benzene Conversion in a Packed Alumina Bed Continuously Fed with Woody Char Particles2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 7, p. 7670-7677Article in journal (Refereed)
    Abstract [en]

    This Article investigates the decomposition of benzene (as a model tar) over finely dispersed char particles continuously distributed into a packed bed. Fragmented char particles and benzene plus a gasification agent (H2O or CO2) were supplied into a ceramic reactor that was heated electrically. The supplied char particles were retained in the reactor by a bed of alumina grains. Woody char as well as iron-doped and potassium-doped woody char were used. The influence of the gasification agent, char concentration, char weight time (proportional to the instant char mass present in the bed), and bed temperature (600-1050 degrees C) was investigated. Increasing the char concentration and char weight time increased benzene conversions for all tested chars. At similar char weight times, the benzene conversion increased with temperature, whereas the iron- and potassium doped char did not affect the specific conversion. At similar char concentrations, changing the gasification agent from CO2 to steam as well as using doped char led to decreased benzene conversions. This can be explained by accelerated char gasification reactions and thus a diminished char mass in the packed bed. Furthermore, benzene conversion rates were enhanced in the presence of CO2 as compared to steam. As the temperature was increased from 950 to 1050 degrees C, the benzene conversions were slightly reduced. This was interpreted as a combined effect of the enhanced benzene conversion rates and reduced char weight times. The highest benzene conversions achieved in the experiments were approximately 80% at 950-1000 degrees C using CO2 as gasification agent and supplying approximately 20-30 g N m(-3) undoped woody char.

  • 31.
    Morgalla, Mario
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Benzene conversion in a packed bed loaded with biomass char particles2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 1, p. 554-560Article in journal (Refereed)
    Abstract [en]

    This study investigates the conversion of benzene in a packed bed containing fine char particles. Benzene and steam were simultaneously supplied to a tubular ceramic reactor that was heated electrically. Fragmented char particles were suspended and continuously supplied via a separate supply line. A packed bed of crushed alumina balls was positioned in the reactor to retain the char particles. The benzene conversion in the hot char bed was investigated by varying the bed temperature (900–1100 °C), steam concentration (0–27 vol %), and char concentration (5–50 g Nm–3). The highest conversions achieved in the experiments were approximately 75%. At comparable char concentrations, similar benzene conversions occurred at 900 and 1000 °C. Increasing the temperature to 1100 °C or increasing the steam concentration reduced the benzene conversion. The results indicate that the reduced conversion was due to enhanced char gasification reactions at elevated temperatures and steam concentrations and thus to reduced char mass in the packed bed.

  • 32.
    Morgalla, Mario
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Characterization Of Particulate Matter In Biomass Gasification2015In: Proceedings for the 23rd European Biomass Conference and Exhibition / [ed] I. Obernberger, D. Baxter, A.Grassi, P.Helm, ETA-Florence Renewable Energies , 2015, p. 664-667Conference paper (Refereed)
    Abstract [en]

    The purpose of this work is to examine the potential of monitoring heavy tar compounds contained in the product gas of a biomass gasifier. The hot product gas from atmospheric indirect bubbling fluidized bed gasification of wood pellets was extracted. The sampling and conditioning system consisted of a high-temperature dilution probe, a primary thermodenuder and a secondary thermodenuder. Online and semi-online instruments were used to characterize the aerosol in terms of number size distribution and particle mass concentration. The fine mode (mobility equivalent diameter db < 150 nm) was found to mainly consist of heavy tar compounds. An Electrical low­pressure impactor (ELPI) was used to measure this mode with a time resolution of 1 second and thus showed the potential for online measurements of heavy tar.

  • 33.
    Morgalla, Mario
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Decomposition of benzene using char aerosol particles dispersed in a high-temperature filter2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 118, p. 1345-1352Article in journal (Refereed)
    Abstract [en]

    In this study the tar-removal suitability of char particles finely dispersed in a high-temperature filter was investigated. Benzene was selected as the model tar. An aerosol-based method was designed and used to investigate the benzene decomposition behaviour. Two types of char were used: commercially available activated charcoal and pine char prepared in the laboratory. The conversion behaviour of both chars was investigated in the temperature range between 750 and 900 °C using steam as the gasification medium. During the experiments, different benzene concentrations, amounts of deposited char and gas residence times were tested. The results indicate that both activated carbon and pine char reduced the benzene concentration. Activated carbon generally produced higher and more stable benzene conversions compared to the pine char particles. Decreasing the benzene concentration or increasing the gas residence time or char mass improved the benzene conversion. It was concluded that the char gasification rate became slower while benzene was simultaneously converted. The aerosol-based method was also used to investigate benzene decomposition behaviour while continuously supplying fresh char particles together with steam at 1000 °C. In that way, the deactivated and gasified char particles were steadily replaced, preventing the benzene conversion from decreasing over time.

  • 34.
    Pettersson, Jens
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Charging- and removal efficiency of an ESP in a 250 kW biomass boiler2011In: International Conference on Electrostatic Precipitation XII, ICESP Nürnberg 2011, 2011Conference paper (Refereed)
    Abstract [en]

    The combustion of biomass creates ultra fine particulate matter which is not precipitated by traditional multi cyclone technique, usually adopted on small scale plants. In Sweden the number of small bio fuelled plants is increasing and there is a need for cost effective means to precipitate the ultra fine particles formed. One such technique may be electrostatic precipitation, but the economy of scale is a constraining factor for systems commercially available today. This paper describes field tests of a low cost electrostatic precipitator, ESP, including not only investigation of collection efficiency, but also measurement of charging effectiveness. The aim of the tests was to determine the potential for the low cost ESP design to form part of an electrostatic precipitation system for use on bio fuelled plants in the megawatt scale. The charges acquired by the particles have been measured using a low pressure cascade impactor, ELPI. Measurements of charges were carried out on particles escaping from the ESP. The results of the measurements of particle charges indicates that the method may correctly reflect the mean charge levels of particles of the different sizes usually found within the fine particle mode of flue gases from biomass combustion.

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  • 35.
    Pettersson, Jens
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Charging and removal efficiency of an ESP in a 250 kW biomass boiler2012In: International Journal of Plasma Environmental Science and Technology, ISSN 1881-8692, Vol. 6, no 3, p. 204-209Article in journal (Refereed)
    Abstract [en]

    The combustion of biomass creates ultra-fine particulate matter which is not precipitated by traditional multi cyclone technique, usually adopted on small scale plants. In Sweden the number of small bio fuelled plants is increasing and there is a need for cost effective means to precipitate the ultra-fine particles formed. One such technique may be electrostatic precipitation, but the economy of scale is a constraining factor for systems commercially available today. This paper describes field tests of a low cost electrostatic precipitator, ESP, including not only investigation of collection efficiency, but also measurement of charging effectiveness. The aim of the tests was to determine the potential for the low cost ESP design to form part of an electrostatic precipitation system for use on bio fuelled plants in the megawatt scale. The charges acquired by the particles have been measured using a low pressure cascade impactor, ELPI. Measurements of charges were carried out on particles escaping from the ESP. The results of the measurements of particle charges indicates that the method may correctly reflect the mean charge levels of particles of the different sizes usually found within the fine particle mode of flue gases from biomass combustion.

  • 36.
    Pettersson, Jens
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strand, Michael
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kostnadseffektiv partikelavskiljning i mindre närvärmeanläggningar2011Report (Other academic)
    Abstract [sv]

    Avsliljningstekniker för mindre biobränsleanläggningar, i storlek under 10 megawatt, har undersökts. Experiment i laboratorium och fältförsök har utförsts avseende elektrostatiska filter.

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    fulltext
  • 37.
    Strand, Michael
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Gustafsson, Eva
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lin, Leteng
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Yang, Jingjing
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    High-Temperature extraction of aerosol particles from biomass combustion and gasification2011In: European Aerosol Conference 2011, 2011Conference paper (Refereed)
  • 38.
    Wang, Chaoqian
    et al.
    Shandong University, China.
    Wang, Wenlong
    Shandong University, China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Zhang, Fusen
    Shandong University, China.
    Zhang, Runing
    Shandong University, China.
    Sun, Jing
    Shandong University, China.
    Song, Zhanlong
    Shandong University, China.
    Mao, Yanpeng
    Shandong University, China.
    Zhao, Xiqiang
    Shandong University, China.
    A stepwise microwave synergistic pyrolysis approach to produce sludge-based biochars: Feasibility study simulated by laboratory experiments2020In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 272, p. 1-10, article id 117628Article in journal (Refereed)
    Abstract [en]

    A stepwise microwave synergistic pyrolysis (SMSP) approach is proposed as a new way to relieve disposal problems of the sewage sludge. Here the sludge is first pre-pyrolyzed by a conventional heating stage, and then rapidly pyrolyzed by a microwave-induced heating stage without any extra microwave absorbers or blending needed. Under simulated process pyrolysis conditions, the dried sludge, intermediate and final sludge-based biochar samples were prepared in the laboratory. Their chemical composition, microstructure and morphology, and leaching toxicity of heavy metals were carefully characterized and analyzed by various techniques such as proximate and ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy (SEM-EDX). Results showed that the pre-pyrolytic biochar can be rapidly heated up to 1100 °C within 5 min under microwave irradiation. The pre-pyrolytic stage increased the carbonization and ash enrichment degree of the sludge which itself acted as a good microwave absorber while achieving a quick temperature rise under microwave irradiation. The ash remaining ratio and the specific surface area of the biochar derived from the SMSP approach (labelled as SBC2) are increased by 6.46% and 16.17% respectively, compared with the conventional biochar sample (SBC1). And SBC2 still had diverse surface functional groups kept after SMSP. The residual ratios of Ni, Cu, Zn, Pb, Cr and Cd in SBC2 was more noticeable than in SBC1 but the leaching ratios quite the contrary. Vitrification is also well proved by the increment of quartz peak detected by XRD tests, and the formation of melted glassy spheres with elemental composition of Si, Ca, Al observed by SEM-EDX. It can favorably increase solidification level and decrease leaching toxicity of heavy metals in the SBC2. The feasibility of this proposed SMSP concept has been positively supported by our experimental results. The properties of the sludge-based biochar produced from the SMSP approach also show great potential to be utilized as precursors to produce various adsorbents.

  • 39.
    Yang, Jingjing
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Gjövik Univ Coll, Norway.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Morgalla, Mario
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Gebremedhin, Alemayehu
    Gjövik Univ Coll, Norway.
    Strand, Michael
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    High-Temperature Characterization of Inorganic Particles and Vapors in a Circulating Fluidized Bed Boiler Cofiring Wood and Rubber Waste2015In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 29, no 2, p. 863-871Article in journal (Refereed)
    Abstract [en]

    The effects of varying fuel mixtures and using a lime additive were studied in a 125-MWth circulating fluidized bed boiler. A high-temperature aerosol measurement method using a hot-dilution probe was used to characterize the particles and condensing inorganic vapors upstream from the superheater. The particle size distributions of the extracted samples indicate that when high-sulfur rubber waste, waste wood, and forest fuel were cocombusted, the hot flue gas contained no substantial amount of particulate matter in the fine (<0.3 mu m) particle size range, although the SO2 concentration exceeded 70 ppm. Only a nucleation mode was observed, which was presumably formed from inorganic vapors that condensed in the sampling probe. The size-segregated elemental analysis of the extracted samples indicated that when lime was added, the nucleation mode mainly comprised condensed alkali chlorides, while the sulfates dominated the mode when no lime was added. The presumed explanation for the sulfates in the nucleation mode was the sulfation of the alkali chlorides inside the sampling system. When only the wood fuels and no rubber fuel were cocombusted, the SO2 concentration in the gas was approximately 5 ppm. In this case, an alkali sulfate particle mode formed at approximately 70 nm in the hot flue gas. In addition, vapors of alkali chlorides and lead formed particulate matter inside the sampling probe when using low dilution ratios.

  • 40.
    Zhang, Xiaorong
    et al.
    Shandong University, China.
    Zhang, Fusen
    Shandong University, China.
    Song, Zhanlong
    Shandong University, China.
    Lin, Leteng
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Zhao, Xiqiang
    Shandong University, China.
    Sun, Jing
    Shandong University, China.
    Mao, Yanpeng
    Shandong University, China.
    Wang, Wenlong
    Shandong University, China.
    Review of chemical looping process for carbonaceous feedstock Conversion: Rational design of oxygen carriers2022In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 325, article id 124964Article, review/survey (Refereed)
    Abstract [en]

    The chemical looping partial oxidation (CLPO) process as a technology of chemical looping process (CLP) is recognized as a potential strategy for the efficient and clean conversion of fuels into syngas/H2. Herein, in view of the importance of low-cost high-performance metal oxides as oxygen carriers (OCs) for this conversion, we systematically review the classification and CLPO applications of such OCs and discuss the improvement of OC reactivity and stability via the creation of metal–metal or metal–support synergism, the generation of oxygen vacancies, and the enhancement of deactivation resistance. Further, we present the results of theoretical and experimental characterizations probing ion diffusion and surface reactions to provide insights into the related reaction mechanisms and touch on the challenges and opportunities of developing metal oxides with excellent reactivity and long-term cycling stability in CLP. Thus, this review facilitates the design and performance regulation of OCs for future energy conversion systems.

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