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  • 1.
    Chen, Tao
    et al.
    Chalmers University of Technology, Sweden.
    Li, Tian
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. NTNU Norwegian University of Science and Technology, Norway.
    Sjöblom, Jonas
    Chalmers University of Technology, Sweden.
    Ström, Henrik
    Chalmers University of Technology, Sweden; NTNU Norwegian University of Science and Technology, Norway.
    A reactor-scale CFD model of soot formation during high-temperature pyrolysis and gasification of biomass2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 303, artikkel-id 121240Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soot generation is an important problem in high-temperature biomass gasification, which results in both air pollution and the contamination of gasification equipment. Due to the complex nature of biomass materials and the soot formation process, it is still a challenge to fully understand and describe the mechanisms of tar evolution and soot generation at the reactor scale. This knowledge gap thus motivates the development of a comprehensive computational fluid dynamics (CFD) soot formation algorithm for biomass gasification, where the soot precursor is modeled using a component-based pyrolysis framework to distinguish cellulose, hemicellulose and lignin. The model is first validated with pyrolysis experiments from different research groups, after which the soot generation during biomass steam gasification in a drop-tube furnace is studied under different operating temperatures (900–1200 °C) and steam/biomass ratios. Compared with the predictions based on a detailed tar conversion model, the current algorithm captures the soot generation more reasonably although a simplified tar model is used. Besides, the influence of biomass lignin content and the impact of tar and soot consumptions on the soot yield is quantitatively studied. Moreover, the impact of surface growth on soot formation is also discussed. The current work demonstrates the feasibility of the coupled multiphase flow algorithm in the prediction of soot formation during biomass gasification with strong heat/mass transfer effects. In conclusion, the model is thus a useful tool for the analysis and optimization of industrial-scaled biomass gasification. © 2021 The Author(s)

  • 2.
    Dimitriadis, Athanasios
    et al.
    CPERI & CERTH, Greece.
    Bergvall, Niklas
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Johansson, Ann-Christine
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Sandström, Linda
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Bezergianni, Stella
    CPERI & CERTH, Greece.
    Tourlakidis, Nikos
    CPERI & CERTH, Greece.
    Meca, Ludek
    Ranido sro, Czech Republic.
    Kukula, Pavel
    Ranido sro, Czech Republic.
    Raymakers, Leonard
    HyET Hydrogen BV, Netherlands.
    Biomass conversion via ablative fast pyrolysis and hydroprocessing towards refinery integration: Industrially relevant scale validation2023Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 332, artikkel-id 126153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reducing the use of fossil fuels is an ongoing and important effort considering the environmental impact and depletion of fossil-based resources. The combination of ablative fast pyrolysis and hydroprocessing is explored as a pathway allowing bio-based intermediates (BioMates) integration in underlying petroleum refineries. The proposed technology is validated in industrially relevant scale, identifying pros and cons towards its commercialization. Straw from wheat, rye and barley was fed to ablative fast pyrolysis rendering Fast Pyrolysis Bio-Oil (FPBO) as the main product. The FPBO was stabilized via slurry hydroprocessing, rendering a stabilized FPBO (sFPBO) with 49 % reduced oxygen content, 71 % reduced carbonyl content and 49 % reduced Conradson carbon residue. Fixed bed catalytic hydroprocessing of sFPBO resulted in the production of BioMates, a high bio-content product to be co-fed in established refinery units. Compared to the starting biomass, BioMates has 83.6 wt% C content increase, 92.5 wt% O content decrease, 93.0 wt% water content decrease, while the overall technology has 20 wt% conversion yield (32 wt% carbon yield) from biomass to BioMates. © 2022 The Author(s)

  • 3.
    Fooladgar, Ehsan
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Brackmann, Christian
    Lund University, Sweden.
    Mannazhi, Manu
    Lund University, Sweden.
    Ögren, Yngve
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Bengtsson, Per-Erik
    Lund University, Sweden.
    Wiinikka, Henrik
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Tóth, Pal
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi. University of Miskolc, Hungary.
    CFD modeling of pyrolysis oil combustion using finite rate chemistry2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 299, artikkel-id 120856Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports the first Computational Fluid Dynamics (CFD) model developed for biomass pyrolysis oil spray combustion using Finite-Rate Chemistry (FRC) approach. To make the CFD calculations feasible, a reduced mechanism for modeling the combustion of biomass Fast Pyrolysis Oil (FPO) based on the POLIMI 1412 mechanism and a model for eugenol oxidation was developed. The reduced mechanism consisted of 200 reactions and 71 species. This level of complexity was found to be a good tradeoff between predictive power and computational cost such that the reduced model could be used in CFD modeling. The predictive power of the reduced mechanism was demonstrated via 0D (adiabatic, premixed, constant pressure reactor), 1D (laminar counterflow flame) and 3D (CFD of a methane-air flat-flame piloted FPO spray flame) calculations. Results from CFD were compared against experimental data from non-intrusive optical diagnostics. The reduced model was successfully used in CFD calculations—the computational cost was approximately 2 orders of magnitude higher than that of a simplified model. Using the reduced mechanism, the concentration of pollutants, minor combustion products, and flame radicals could be predicted—this is added capability compared to already existing models. The CFD model using the reduced mechanism showed quantitative predictive power for major combustion products, flame temperature, some pollutants and temperature, and qualitative predictive power for flame radicals and soot. © 2021 The Authors

  • 4.
    Gogolev, Ivan
    et al.
    Chalmers University of Technology, Sweden.
    Soleimanisalim, Amir H
    Chalmers University of Technology, Sweden.
    Linderholm, Carl
    Chalmers University of Technology, Sweden.
    Lyngfelt, Anders
    Chalmers University of Technology, Sweden.
    Commissioning, performance benchmarking, and investigation of alkali emissions in a 10 kWth solid fuel chemical looping combustion pilot2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chemical looping combustion of biomass-sourced fuels (bio-CLC) is a novel bio-energy with carbon capture and storage (BECCS) technology for power and heat generation with net negative CO2 emissions. In this study, a new 10 kWth CLC pilot designed for high-volatiles biomass fuels was commissioned with ilmenite oxygen carrier and five different biomass fuels of varying volatile and alkali content fractions. The system was tested for its ability to convert high and low volatile content biomass, while achieving high carbon capture efficiency. The new pilot achieved carbon capture close to 100% for high-volatiles biomass, and >94% for low-volatiles biomass char fuels. Furthermore, due to the implementation of a volatiles distributor, the new pilot demonstrated an improvement of up to 10 percentage points of gas conversion efficiency for high-volatiles biomass vs. the previous generation reactor. Gaseous alkali emissions were measured with a surface ionization detection system. Flue gas alkali release levels were found to rise with higher fuel alkali content. Alkali emissions were found to be approximately similar in the AR and the FR for all but the straw pellet mixture fuel (highest alkali content fuel). For the straw pellet mixture, gaseous alkali release levels in the AR were up to seven times higher than those of the FR. In all cases, over 96% of the fuel’s alkalis were absorbed by the ilmenite bed material. Ilmenite’s strong alkali absorption characteristics were concluded to be the key determinant of gas-phase release of biomass alkali in the conducted experiments. 

  • 5.
    Göktepe, Burak
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    Hazim, Ammar
    Luleå University of Technology, Sweden.
    Lundström, Staffan
    Luleå University of Technology, Sweden.
    Gebart, Rikard
    Luleå University of Technology, Sweden.
    Soot reduction in an entrained flow gasifier of biomass by active dispersion of fuel particles2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, s. 111-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soot is an undesired by-product of entrained flow biomass gasification since it has a detrimental effect on operation of the gasifier, e.g. clogging of flow passages and system components and reduction of efficiency. This study investigated how active flow manipulation by adding synthetic jet (i.e. oscillating flow through orifice) in feeding line affects dispersion of fuel particles and soot formation. Pine sawdust was gasified at the conditions similar to pulverized burner flame, where a flat flame of methane-air sub-stoichiometric mixture supported ignition of fuel particles. A synthetic jet flow was supplied by an actuator assembly and was directed perpendicular to a vertical tube leading to the center of the flat flame burner through which pine sawdust with a size range of 63-112. μm were fed into a reactor. Quartz filter sampling and the laser extinction methods were employed to measure total soot yield and soot volume fraction, respectively. The synthetic jet actuator modulated the dispersion of the pine sawdust and broke up particle aggregates in both hot and cold gas flows through generation of large scale vortex structures in the flow. The soot yield significantly reduced from 1.52. wt.% to 0.3. wt.% when synthetic jet actuator was applied. The results indicated that the current method suppressed inception of young soot particles. The method has high potential because soot can be reduced without changing major operation parameters. © 2016.

  • 6.
    Han, Tong
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sophonrat, Nanta
    KTH Royal Institute of Technology, Sweden.
    Tagami, Ayumu
    KTH Royal Institute of Technology, Sweden ; Nippon Paper Industries Co., Japan.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    Mellin, Pelle
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB AB.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Characterization of lignin at pre-pyrolysis temperature to investigate its melting problem2019Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 235, s. 1061-1069Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Technical lignin particles melt under relatively low temperature. This results in the problem in the continuous feeding and fluidization during lignin pyrolysis, which in turn limits its utilization on a large scale. In this study, two most available types of lignin have been used to investigate the lignin melting problem, which are Kraft lignin (KL) from pulping process and hydrolysis lignin (HL) from bio-ethanol production process. Elemental composition, thermal property and thermally decomposed derivatives of each sample are tested by elemental analyzer, TGA, DSC, and Py-GC/MS. Morphology, structure and crystal change before and after heat treatment are tested by microscopy, FTIR and XRD. All results suggest that lignin structure determines its melting properties. Kraft lignin from pulping process contains a less cross-linked structure. It melts under heating. On the other hand, hydrolysis lignin from hydrolysis process contains a highly crossed-linked and condensed structure. It does not melt before decomposition under heat treatment. Modifying lignin structure is suggested for the resolution of technical lignin melting problem.

  • 7.
    Hedayati, Ali
    et al.
    TECNALIA, Spain.
    Soleimanisalim, Amir H
    Chalmers University of Technology, Sweden.
    Mattisson, Tobias
    Chalmers University of Technology, Sweden.
    Lyngfelt, Anders
    Chalmers University of Technology, Sweden.
    Thermochemical conversion of biomass volatiles via chemical looping: Comparison of ilmenite and steel converter waste materials as oxygen carriers2022Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 313Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two oxygen carriers were tested with respect to chemical looping combustion (CLC) and chemical looping gasification (CLG). Ilmenite, a natural ore composed mainly of iron–titanium oxide, and LD Slag, an iron-based industrial waste, were investigated at 850 and 900 °C in a continuous operation in a 0.3 kW chemical-looping reactor system using synthetic biomass volatiles as fuel. CLC and CLG conditions were simulated in the fuel reactor by changing the fuel flow rates. In the case of ilmenite the syngas yield and methane conversion increased with fuel flow rate. Consequently, the syngas to hydrocarbon ratio was higher for ilmenite. Methane conversion improved for both tested oxygen carriers with increasing the operating temperature. Oxygen release was observed in the case of LD Slag. The H2/CO ratio was between 0.7 and 0.8 for both oxygen carriers at the higher fuel flows. With respect to CLC, ilmenite showed higher gas conversion than LD slag. Analysis of the particles revealed that ilmenite possessed better mechanical properties and formed less dust compared to LD Slag during the continuous operation with fuel. 

  • 8.
    Hildor, Fredrik
    et al.
    Chalmers University of Technology, Sweden.
    Soleimanisalim, Amir H
    Chalmers University of Technology, Sweden.
    Seemann, Martin
    Chalmers University of Technology, Sweden.
    Mattisson, Tobias
    Chalmers University of Technology, Sweden.
    Leion, Henrik
    Chalmers University of Technology, Sweden.
    Tar characteristics generated from a 10 kWth chemical-looping biomass gasifier using steel converter slag as an oxygen carrier2023Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 331Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tar management is one of the key components to achieve high energy efficiency and low operational costs connected to thermal gasification of biomass. Tars contain a significant amount of energy, and unconverted tars result in energy efficiency losses. Also, heavy tars can condense downstream processes, resulting in increased maintenance. Dual fluidized beds for indirect gasification operated with active bed material can be a way to better convert and control the tar generated in the process. Using an active material to transport oxygen in an indirect dual reactor gasification setup is referred to as chemical-looping gasification (CLG). A higher oxidative environment in the gas phase, in addition to possible catalytic sites, could mean lower yields in comparison to normal indirect gasification. This paper investigates the effect of using Steel converter slag (LD slag), a byproduct of steel manufacturing, as an oxygen-carrying bed material on tar species generated in a 10 kWth dual fluidized bed biomass gasifier. The results are compared to the benchmark oxygen carrier ilmenite and conventional silica sand. Three different solid biofuels were used in the reactor system: steam exploded pellets, pine forest residue and straw. Tar was absorbed from the raw syngas using a Solid Phase Adsorption (SPA) column and was analyzed using GC-FID. Bench-scale experiments were also performed to investigate benzene conversion of LD slag and ilmenite at different oxidation levels. The findings of this study suggest that oxygen carriers can be used to decrease the tars generated in a dual fluidized bed system during gasification. Phases in LD slag possess catalytic properties, resulting in a decreased ratio of heavy tar components compared to both ilmenite and sand. Temperature and fuel load showed a significant effect on the tar generation compared to the circulation and steam ratio in this reactor system. Increased temperature generated lower tar yields and lower ratios of heavy tar components for LD slag in contrast to sand.

  • 9.
    Holmgren, Per
    et al.
    Umeå University, Sweden.
    Wagner, David R.
    Umeå University, Sweden.
    Strandberg, Anna
    Umeå University, Sweden.
    Molinder, Roger
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Umeki, Kentaur
    Luleå University of Technology, Sweden.
    Broström, Markus
    Umeå University, Sweden.
    Size, shape, and density changes of biomass particles during rapid devolatilization2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, s. 342-351Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Particle properties such as size, shape and density play significant roles on particle flow and flame propagation in pulverized fuel combustion and gasification. A drop tube furnace allows for experiments at high heating rates similar to those found in large-scale appliances, and was used in this study to carry out experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion. The objective of this study was to develop a particle conversion model based on optical information on particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved to three narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized using optical methods. Different shape descriptors were evaluated and a shape descriptor based on particle perimeter was found to give significant information for accurate estimation of particle volume. The optical conversion model developed was proven useful and showed good agreement with conversion measured using a reference method based on chemical analysis of non-volatilized ash forming elements. The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoring of particle conversion, provided density data has been calibrated.

  • 10.
    Ji, Jie
    et al.
    University of Science and Technology of China, China.
    Fan, Chuan Gang
    RISE., SP – Sveriges Tekniska Forskningsinstitut. University of Science and Technology of China, China.
    Li, Ying Zhen
    Ingason, Haukur
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Sun, Jin Hua
    University of Science and Technology of China, China.
    Experimental study of non-monotonous sidewall effect on flame characteristics and burning rate of n-heptane pool fires2015Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 145, s. 228-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To study the influence of sidewall effect on flame characteristics and burning rate, a series of experiments with heptane pools was conducted. The results showed that as the fires were placed close to the sidewall, the flames inclined to the sidewall due to the restriction on air entrainment, and the burning rate increased on the whole, which could be mainly due to the enhanced radiation from the heated sidewall and ceiling flame. However, regardless of fuel pool shape, the burning rate obtained the peak value when the fire was near the sidewall, rather than attached to the sidewall, resulting from less flame radiation from the vertical flame part to the fuel in the latter case. The ratio of longitudinal ceiling flame length to transverse length tended to decrease with the fire moving close to the sidewall. For cases with the largest length and wall fires, the ratio was nearly 0.5, which could be explained according to the theory of mirror effect. Also, due to the non-monotonous sidewall effect, a higher burning rate did not necessarily lead to a larger ceiling flame length.

  • 11.
    Jones, Frida
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik. Åbo Akademi University, Finland.
    Bankiewicz, Dorota
    Åbo Akademi University, Finland.
    Hupa, Mikko
    Åbo Akademi University, Finland.
    Occurrence and sources of zinc in fuels2014Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 117, nr A, s. 763-775Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several studies have shown that the presence of high amounts of Zn, in addition to other elements, in fuels can be a cause of operational difficulties during combustion due to corrosion and slagging and can also cause environmental and health problems due to emissions. In nature, Zn is an essential micronutrient for humans, animals and plants, but in excessive amounts it becomes toxic. This paper presents a review on the content of Zn in different fuels used in energy conversion systems. Altogether, over 20 different fuels divided among waste, biomass and fossil fuels were studied. The highest amounts of Zn are present in waste-derived fuels, particularly in Tire-Derived Fuel (TDF). In tires, Zn is used as a vulcanizing agent and can reach concentration values of 9600-16,800 mg kg-1DS. Waste Electrical and Electronic Equipment (WEEE) is the second Zn-richest fuel; while on average Zn content is around 4000 mg kg-1DS., values of over 19,000 mg kg-1DS. were also reported. High amounts of Zn, 3000-4000 mg kg-1DS., are also found in municipal solid waste (MSW), sludge with over 2000 mg kg-1DS. on average (some exceptions up to 49,000 mg kg-1DS.), and other waste-derived fuels (over 1000 mg kg-1DS.). Zn can also be found in fossil fuels. In coal, the level of Zn is quite low, on average 100 mg kg-1DS., while higher amounts of Zn were reported for oil shale, with values between 20 and 2680 mg kg-1DS. The content of Zn in biomass is basically determined by its natural occurrence, typically 10-100 mg kg-1DS.

  • 12.
    Lu, Xiaohu
    et al.
    Nynas AB, Sweden.
    Sjövall, Peter
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    Soenen, Hilde
    Nynas NV, Belgium.
    Andersson, Martin
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering.
    Microstructures of bitumen observed by environmental scanning electron microscopy (ESEM) and chemical analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS)2018Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 229, s. 198-208Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study is to characterize structures induced on bitumen surfaces under analysis by environmental scanning electron microscopy (ESEM), and to examine possible contributing factors to the formation of their formation. Various bitumen samples are investigated, including soft and hard, as well as polymer modified bitumen. Chemical characterization is carried out by time-of-flight secondary ion mass spectrometry (TOF-SIMS), combined with principle component analysis (PCA). The study shows that, for soft bitumen, a tube pattern or worm structure is rapidly formed during ESEM analysis, but for hard bitumen, a longer exposure time is needed to develop a structure. The structures on the hard bitumen are also denser as compared to those on the soft bitumen. When sample specimens are deformed or stretched, the orientation of the created deformation is clearly reflected in the structures formed under ESEM, and for soft bitumen, the structure disappears overnight in vacuum but reappears with the same pattern upon repeated ESEM analysis. TOF-SIMS shows small but consistent chemical differences, indicating higher aliphatic and lower aromatic contents on the surface of the structured area compared to the unstructured area. Based on an estimated temperature increase on the bitumen surface due to the electron-beam irradiation, it is speculated that the ESEM-induced worm structure may be attributed to evaporation of volatiles, surface hardening and local expansion. In addition, under the electron-beam exposure, certain chemical reactions (e.g. breaking of chemical bonds, chain scission and crosslinking) may take place, possibly resulting in the observed chemical differences between the structured and unstructured areas.

  • 13.
    Lu, Xiaohu
    et al.
    Nynas AB, Sweden.
    Soenen, Hilde
    Nynas NV, Belgium.
    Sjövall, Peter
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Pipintakos, Georgios
    University of Antwerp, Belgium.
    Analysis of asphaltenes and maltenes before and after long-term aging of bitumen2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 304, artikkel-id 121426Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Asphaltenes and maltenes of bitumen before and after aging are investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), time of flight - secondary ion mass spectrometry (TOF-SIMS), and gel permeation chromatography (GPC). It has been shown that bitumen differs in terms of wax. After fractionation, more wax is found in the maltenes compared to the bitumen, and this is even more evident when bitumen is aged. For one bitumen, asphaltenes from the virgin binder do not contain carbonyls, which all fall into the maltenes. After bitumen aging, a large part of the carbonyl and sulfoxide signals is shifted to the asphaltenes. Differences in aromaticity are also evidenced as asphaltenes > bitumen > maltenes. TOF-SIMS shows that maltenes are close to the bitumen, but asphaltenes are more different. Also, maltenes are relatively unaffected by aging while larger differences are found in the asphaltenes between the virgin and aged binders. By GPC, a large molecular weight fraction of bitumen is shown as main part of the asphaltenes. However, asphaltenes also contain low molecular weight molecules that overlap with maltenes. Upon bitumen aging, some low molecular weight compounds may become part of asphaltenes, making the average molecular weight of the asphaltenes lower.

  • 14.
    Lu, Xiauhu
    et al.
    Nynas AB, Sweden.
    Sjövall, Peter
    RISE - Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Soenen, Hilde
    Nynas NV, Belgium.
    Structural and chemical analysis of bitumen using time-of-flight secondary ion mass spectrometry (TOF-SIMS)2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 199, s. 206-218Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical composition and structures of bitumen surfaces are characterised using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The effect of wax is considered by comparing a wax-free bitumen with a bitumen that contains natural wax and a wax-free bitumen to which a small amount of wax has been added. The results demonstrate that TOF-SIMS is a powerful method for the chemical characterisation of surface structures and phase segregation phenomena in bitumen. It is evident that the structures formed on the bitumen surface are closely related to the wax content and that these structures, as well as the surface in general, are enriched in wax-related compounds (aliphatic hydrocarbons with a high degree of saturation). For the wax-free bitumen, the surface is characterised by a homogeneous distribution without chemical variations or phase structures and by a stronger signal intensity from aromatic compounds. When adding wax to the wax-free bitumen, extensive wax segregation occurs, but differently from the natural waxy bitumen, no bee structures are observed. Furthermore, fracture surfaces of all the wax-containing samples reveal circular structures, which are distinctly different from those observed on the original surfaces. The obtained chemical knowledge on bitumen surfaces and phase structures is of fundamental importance to understand performance differences of this type of materials.

  • 15.
    Lyne Laurell, Åsa
    et al.
    KTH Royal Institute of Technology, Sweden.
    Wallqvist, Viveca
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Birgisson, Björn
    KTH Royal Institute of Technology, Sweden.
    Adhesive surface characteristics of bitumen binders investigated by Atomic Force Microscopy2013Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 113, s. 248-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bitumen is a complex hydrocarbon whose composition-structure-property relationship is not well-understood. In this paper, microphase-separated topographic morphologies of unaged penetration grade 70/100 bitumen binders have been visualized by means of AFM QNM, and the relationship to local mechanical properties has been demonstrated. AFM QNM is a surface force mapping technique which measures parameters such as topography, adhesion and elastic modulus simultaneously. The resulting data can then be presented as images representing individual or overlaid parameters, e.g. topographic images with an adhesion overlay or topographic images with a modulus overlay. AFM QNM results show that the adhesive forces measured in the region surrounding (peri phase) the periodic topographic features resembling 'bees' (catana phase) and the region in the 'bee' areas are lower than the adhesive force measured in the smooth matrix (para phase). Likewise it was observed that Young's moduli in the region surrounding (peri phase) the 'bees' (catana phase) and in the 'bees' are higher than Young's modulus of the smooth matrix (para phase).

  • 16.
    Marklund, Magnus
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Tegman, R.
    Gebart, Rikard
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    CFD modelling of black liquor gasification: Identification of important model parameters2007Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 86, nr 42351, s. 1918-1926Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressurized high temperature black liquor gasification has the potential to significantly improve the efficiency of energy and chemical recovery in the pulping industry and to enable new processes, e.g. production of renewable automotive fuels from the formed synthesis gas. However, the current process is still considered as novel and the interest in validated computer models for scale-up and process optimisation is large. In this paper a sensitivity analysis on the four most important model parameters in the pre-processing 'droplet composition model' for a proposed CFD model has been performed. It was shown that careful measurements of the amount of sulphur released to the gas phase as H2S during devolatilization and the concentration ratio of Na2S and Na2SO4 in the black liquor char under real process conditions are of great importance for calibration of the model. © 2007 Elsevier Ltd. All rights reserved.

  • 17.
    Moya Nunez, Alice
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Börjesson, Eric
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Kinnunen, Hanna
    Valmet Technologies Oy, Finland.
    Lindberg, Daniel
    Aalto University, Finland.
    Norling, Rikard
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Influence of PbCl2 and KCl salt mixture on high temperature corrosion of alloy 6252024Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 358, artikkel-id 130196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aggressive corrosion can occur when firing waste or bio-based fuels, due to the presence of high concentrations of heavy metals, alkali metals, and chlorides. These deleterious compounds deposit on furnace walls and can form mixtures that can rapidly accelerate corrosion. The effect of salts containing lead had not been studied extensively at temperatures lower than 400 °C in nickel-based materials. This study investigates the effect of the individual salts PbCl2 and KCl and their mixture on the high temperature corrosion of alloy 625 at 340 °C and 380 °C. Samples of alloy 625 were covered with individual salts or a salt mixture and exposed to high temperatures in an atmosphere of synthetic air, 20-vol% H2O, and 100 ppm HCl. The results show that the presence of individual salts does not induce observable corrosion attack on alloy 625 after 168 h at any tested temperature. The salt mixture did cause a severe corrosion attack at 380 °C, observed after 24 h of exposure. It is suggested that the salt mixture induces the formation of lead chromates that may prevent or disrupt the formation of a protective chromia scale. It is believed that a key part of the mechanism is the formation of eutectic melts by the interaction of the scale with the salt mixture. Thermodynamic equilibria calculations show that the first melting temperature of PbCl2 and KCl salt mixture after reaction with oxygen can be as low as about 382 °C, and even lower (357 °C) if chromates are present. 

  • 18. Paulrud, S.
    et al.
    Nilsson, C.
    Ohman, M.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Reed canary-grass ash composition and its melting behaviour during combustion2001Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 80, nr 10, s. 1391-1398Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spring harvested reed canary-grass (RCG) with various chemical compositions was combusted in a 180 kW boiler. The ash melting behaviour was studied and the ash was analysed. Estimation of melting behaviour was done by ASTM fusion test, a bench-scale fluidized-bed combustion test (5 kW), and by extracting melting behaviours from the ternary phase diagram SiO2-CaO-K2O. The initial melting temperatures seem to be similar for the different samples; however, for low ash content (3-4% DM) higher portions of melt occurred in the lower temperature range <1200°C and for high ash content fuels (5-10%) more melting occurred in a higher temperature range, >1500°C. © 2001 Elsevier Science Ltd. All rights reserved.

  • 19.
    Purnomo, Victor
    et al.
    Chalmers University of Technology, Sweden.
    Staničić, Ivana
    Chalmers University of Technology, Sweden.
    Mei, Daofeng
    Chalmers University of Technology, Sweden.
    Soleimanisalim, Amir H
    Chalmers University of Technology, Sweden.
    Mattisson, Tobias
    Chalmers University of Technology, Sweden.
    Rydén, Magnus
    Chalmers University of Technology, Sweden.
    Leion, Henrik
    Chalmers University of Technology, Sweden.
    Performance of iron sand as an oxygen carrier at high reduction degrees and its potential use for chemical looping gasification2023Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron sand as an industrial by-product has a reasonable iron content (35 wt% Fe) and low economical cost. The reactivity of iron sand as an oxygen carrier was examined in a bubbling fluidized bed reactor using both gaseous and solid fuels at 850–975 °C. Pre-reductions of iron sand were performed prior to fuel conversion to adapt the less-oxygen-requiring environment in chemical looping gasification (CLG). Based on the investigations using CO and CH4, iron sand has an oxygen transfer capacity of around 1 wt%, which is lower than that of ilmenite. The conversion of pine forest residue char to CO and H2 was higher when using iron sand compared to ilmenite. Depending on the mass conversion degree of iron sand, the activation energy of pine forest residue char conversion using iron sand was between 187 and 234 kJ/mol, which is slightly lower than that of ilmenite. Neither agglomeration nor defluidization of an iron sand bed occurred even at high reduction degrees. These suggests that iron sand can be utilized as an oxygen carrier in CLG. Furthermore, this study presents novel findings in the crystalline phase transformation of iron sand at various degrees of oxidation, altogether with relevant thermodynamic stable phases. 

  • 20.
    Rebaque, Virginia
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Ertesvåg, Ivar
    NTNU Norwegian University of Science and Technology, Norway.
    Fjellgaard Mikalsen, Ragni
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. Western Norway University of Applied Sciences, Norwaay; Otto von Guericke University Magdeburg, Germany.
    Steen-Hansen, Anne
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Experimental study of smouldering in wood pellets with and without air draft2020Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 264, artikkel-id 116806Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dry wood pellets (diameter 8 mm) of mixed Norwegian spruce and pine were tested in samples of 1.25 kg (1.7 l) in configurations with and without air draft from below. The pellets were placed in a vertical 15 cm diameter cylinder on top of a hot plate. Air draft inlet, when allowed, came through narrow openings in the cylinder bottom periphery. The bulk void of 36% formed channels for gas flows within the pellets bed. Initially, the samples were heated externally from below for 6 h. Time series of distributed temperatures were recorded, together with values of the mass. Smouldering with air draft was observed with two distinct behaviours: Type 1, where the sample after the period of external heating cooled down for several hours, and then increased in temperature to intense smouldering, and Type 2, where the sample went into intense smouldering before the end of external heating. Without draft airflow from below, the sample cooled down after external heating, before developing into intense smouldering about 20 h later. In all cases, the intense period lasted for 2 h. Typical temperatures were in the range 300–450 °C, while higher temperatures occurred in the intense period. Draft flow caused fast oxidation spreading, while slow without draft. Indications of oxidation spreading as a distriäbuted reaction were seen. Circulating air motions in the irregular void between individual pellets is discussed as an explanation for the behaviour. Uneven access to oxygen, with possibilities of locally excess air, can explain the peak temperatures observed. © 2019 The Author(s)

  • 21.
    Risberg, Mikael
    et al.
    Luleå University of Technology, Sweden.
    Öhrman, Olov .G.W
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, B. Rikard
    Luleå University of Technology, Sweden.
    Nilsson, Patrik T.
    Lund University, Sweden.
    Gudmundsson, Anders
    Lund University, Sweden.
    Sanati, Mehri
    Lund University, Sweden.
    Influence from fuel type on the performance of an air-blown cyclone gasifier2014Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 116, s. 751-759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Entrained flow gasification of biomass using the cyclone principle has been proposed in combination with a gas engine as a method for combined heat and power production in small to medium scale (<20 MW). This type of gasifier also has the potential to operate using ash rich fuels since the reactor temperature is lower than the ash melting temperature and the ash can be separated after being collected at the bottom of the cyclone. The purpose of this work was to assess the fuel flexibility of cyclone gasification by performing tests with five different types of fuels; torrefied spruce, peat, rice husk, bark and wood. All of the fuels were dried to below 15% moisture content and milled to a powder with a maximum particle size of around 1 mm. The experiments were carried out in a 500 kWth pilot gasifier with a 3-step gas cleaning process consisting of a multi-cyclone for removal of coarse particles, a bio-scrubber for tar removal and a wet electrostatic precipitator for removal of fine particles and droplets from the oil scrubber (aerosols). The lower heating value (LHV) of the clean producer gas was 4.09, 4.54, 4.84 and 4.57 MJ/Nm3 for peat, rice husk, bark and wood, respectively, at a fuel load of 400 kW and an equivalence ratio of 0.27. Torrefied fuel was gasified at an equivalence ratio of 0.2 which resulted in a LHV of 5.75 MJ/Nm3 which can be compared to 5.50 MJ/Nm3 for wood powder that was gasified at the same equivalence ratio. A particle sampling system was designed in order to collect ultrafine particles upstream and downstream the gasifier cleaning device. The results revealed that the gas cleaning successfully removed >99.9% of the particulate matter smaller than 1 μm.

  • 22.
    Sedlmayer, Irene
    et al.
    Vienna University of Technology, Austria; BIOENERGY 2020+ GmbH, Germany.
    Arshadi, Mehrdad
    SLU Swedish University of Agricultural Sciences, Sweden.
    Haslinger, Walter
    BIOENERGY 2020+ GmbH, Germany; Luleå University of Technology, Sweden.
    Hofbauer, Hermann
    Vienna university of Technology, Austria.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Lönnermark, Anders
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Nilsson, Calle
    SLU Swedish University of Agricultural Sciences, Sweden.
    Pollex, Annett
    DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Germany.
    Schmidl, Christoph
    BIOENERGY 2020+ GmbH, Germany.
    Stelte, Wolfgang
    DTU Technical University of Denmark, Denmark.
    Wopienka, Elisabeth
    BIOENERGY 2020+ GmbH, Germany.
    Bauer-Emhofer, Waltraud
    BIOENERGY 2020+ GmbH, Germany; Vienna University of Technology, Austria.
    Determination of off-gassing and self-heating potential of wood pellets – Method comparison and correlation analysis2018Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 234, s. 894-903Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several methods for identifying the phenomena of self-heating and off-gassing during production, transportation and storage of wood pellets have been developed in recent years. Research focused on the exploration of the underlying mechanisms, influencing factors or the quantification of self-heating or off-gassing tendencies. The present study aims at identifying a clear correlation between self-heating and off-gassing. Thus, different methods for determining self-heating and off-gassing potentials of wood pellets are compared. Therefore, eleven wood pellet batches from the European market were analyzed. For this investigation, three methods for the determination of self-heating, like isothermal calorimetry, oxi-press and thermogravimetric analysis, and four methods for off-gassing, like volatile organic compound (VOC) emissions measurements, gas phase analysis of stored pellets in a closed container by offline and by glass flask method and determination of fatty and resin acids content, were performed. Results were ranked according to the self-heating and off-gassing tendency providing a common overview of the analyzed pellets batches. Relations between different methods were investigated by Spearman's correlation coefficient. Evaluation of the results revealed an equal suitability of offline and glass flask methods to predict off-gassing tendency and indicated a very significant correlation with isothermal calorimetry for the identification of self-heating tendency. The thermogravimetric analysis as well as the fatty and resin acids determination proved to be insufficient for the exclusive assessment of self-heating and off-gassing tendency, respectively.

  • 23.
    Shahrivar, Mohammad
    et al.
    Chalmers University of Technology, Sweden.
    Saeed, Muhammad Nauman
    Chalmers University of Technology, Sweden.
    Surywanshi, Gajanan Dattarao
    Chalmers University of Technology, Sweden.
    Mattisson, Tobias
    Chalmers University of Technology, Sweden.
    Soleimanisalim, Amir H
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Improving bio aviation fuel yield from biogenic carbon sources through electrolysis assisted chemical looping gasification2023Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 348, artikkel-id 128525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The second-generation bio aviation fuel production via Chemical Looping Gasification (CLG) of biomass combined with downstream Fischer-Tropsch synthesis is a possible way to decarbonize the aviation sector. Although CLG has a higher syngas yield and conversion efficiency compared to the conventional gasification processes, the fraction of biogenic carbon which is converted to biofuel is still low (around 28%). To increase carbon utilization and biofuel yield, incorporation of two types of electrolyzers, Polymer Electrolyte Membrane (PEM) and Molten Carbonate Electrolysis Cell (MCEC), for syngas conditioning has been investigated. Full chain process models have been developed using an experimentally validated CLG model in Aspen Plus for Iron sand as an oxygen carrier. Techno-economic parameters were calculated and compared for different cases. The results show that syngas conditioning with sustainable hydrogen from PEM and MCEC electrolyzers results in up to 11.5% higher conversion efficiency and up to 8.1 % higher biogenic carbon efficiencies in comparison to the syngas conditioning with water gas shift reactor. The study shows that the lowest carbon capture rates are found in the configurations with the highest biogenic carbon efficiency which means up to 14% more carbon ends up in FT crude compared to the case with conventional WGS conditioning. Techno-economic analysis indicates that syngas conditioning using PEM and MCEC electrolyzers would result in an increase of the annual profit by a factor of 1.4 and 1.7, respectively, when compared to using only WGS reactors. 

  • 24.
    Sjöström, Johan
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Blomqvist, Per
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Sveriges tekniska forskningsinstitut / Brandteknik, forskning (BRf ).
    Direct measurements of thermal properties of wood pellets: elevated temperatures, fine fractions and moisture content2014Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 134, nr Oct, s. 460-466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The self-heating propensity of biomass fuels is a major challenge to the large scale handling of e.g. wood pellets. The insulating properties in combination with exothermal processes sometimes lead to fires when larger volumes of wood pellets are stored. Recently, the thermal conductivity and specific heat of wood pellets have been investigated (Gou et al., 2013) through back-calculations of transient temperatures in wood bulk storage. Such properties are important in order to make simulations and predictions about safe storage and use. However, little information is available about the temperature dependence of these properties as well as the bulk properties of broken pellets, which is abundant in critical parts of a storage facility. In this study we show that the specific heat and thermal conductivity of wood pellets can be directly measured using the Transient Plane Source technique. We present data between 22 and 120 °C for bulk wood pelletsand investigate the change in conductivity for fine particle bulk material. In addition, we investigate the possibility of measuring on individual pellets while studying the moisture contentdependence.

  • 25.
    Sjövall, Peter
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Bake, Kyle
    Schlumberger-Doll Research, USA.
    Pomerantz, Andrew
    Schlumberger-Doll Research, USA.
    Lu, Xiaohu
    Nynäs AB, Sweden.
    Mitra-Kirtley, Sudipa
    Rose-Hulman Institute of Technology, USA.
    Mullins, Oliver
    Schlumberger-Doll Research, USA.
    Analysis of kerogens and model compounds by time-of-flight secondary ion mass spectrometry (TOF-SIMS)2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 286, artikkel-id 119373Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, kerogens of differing heat treatments are subjected to extremely high dissociation energies by sample bombardment by 25 keV Bi3+ primary ions during analysis by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Positive and negative secondary ions are produced from this decomposition and fragment ion distributions of model compounds and kerogens are compared and starkly different results are obtained for cations versus anions. Cations exhibit a large range of C/H ratios and include highly unsaturated linear chain ions and aromatic ions. Cations of kerogens possess predominantly no heteroatoms. Positive fragment ion distributions depend on the source material being bombarded. Mature, more aromatic kerogens produce higher yields of fragment ions of highly unsaturated carbon chains while immature, more aliphatic kerogens produce more aromatic fragment ions, particularly at the higher carbon numbers. This is consistent with the observation that aromatic model compounds produce a greater fraction of hydrogen-deficient, carbon chain fragment ions, as compared to a purely aliphatic model compound. There is substantial suppression of free radical fragment cations, except for large fragments. In contrast, there is little free radical suppression of the anions. The anions tend to be very hydrogen deficient, spanning a small range of C/H ratios. Highly unsaturated to pure carbon chain fragment anions dominate while aromatic anions are not found. In both positive and negative ion spectra, the yields of fragment ions corresponding to derivatives of the carbon chain molecules, polyynes and allenes, are substantial. Some heteroatom-containing fragment anions are produced, all of which are very hydrogen deficient. 

  • 26.
    Sjövall, Peter
    et al.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    Pomerantz, Andrew E.
    Schlumberger-Doll Research, USA.
    Lu, Xiaohu
    Nynäs AB, Sweden.
    Mullins, Oliver C.
    Schlumberger-Doll Research, USA.
    Time of flight-secondary ion mass spectrometry (TOF-SIMS) study of diverse asphaltenes2018Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 220, s. 638-644Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mass spectrometry has been used to elucidate a large variety of properties of asphaltenes. Here, time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to probe three diverse asphaltene types with wide ranging fractions of alkyl carbon to the sum of alkyl plus aromatic carbon (Rc), immature source rock asphaltenes (ISA with Rc ∼ 0.75); petroleum asphaltenes (PA with Rc ∼ 0.5); and coal-derived asphaltenes (CDA with Rc ∼ 0.25). In addition, the asphaltenes from a commercial bitumen are examined. Primary ion surface bombardment using the Bi3 + ion yields high energy density of deposition and significant molecular fragmentation with secondary ion formation. Formation of free radical cation fragments is generally suppressed especially for smaller fragments except for specific cases. Possible structures, especially cations of common aromatic compounds, are suggested for fragments with relatively large cross section of formation. Principal component analysis of the fragmentograms allows identification of key properties of the complex fragmentation patterns for the different samples. Comparisons of TOF-SIMS fragmentograms show a fundamental difference for small fragments between CDAs and all petroleum derived asphaltenes with CDAs being dominated by aromatic carbon fragments whereas all petroleum derived asphaltenes show a large fraction of fragments from alkyl carbon. However, the type of alkyl carbon fragments did not exhibit systematic trends with Rc, nor with the extent of chemical reaction or chemical processing of the materials. Consequently, it appears that having an appreciable alkane fraction is a basic property of petroleum derived asphaltenes, but the exact type of alkane carbon for differing samples of these asphaltenes is more idiosyncratic than systematic. 

  • 27.
    Strömberg, Niklas
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Eriksson, Henrik
    Scania, Sweden.
    Saramat, Ali
    Scania, Sweden.
    Determination of phase separation efficiency for biodiesel quality and blending2014Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 117, nr pt A, s. 74-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study we reintroduce phase separation efficiency as an important characteristic for biodiesel quality and blending. The ability of the fuel to emulsify water is possibly one of the most important features behind biological and chemical fuel degradation but yet, no methods that directly measure this property are included in the standard biodiesel regulation EN14214. The proposed simple technique for fuel quality testing is based on the time it takes for ultra-purified water to become transparent after complete mixing with an equal volume of fuel, measured by kinetic absorbance spectrophotometry. In this study we screen the phase separation efficiency (measured as separation time) of purified, un-aged and aged Fatty Acid Methyl Esters (FAME/B100) and its blends with EN590 with 7% FAME without detergents (B7 reference fuel Euro VI Part no 546061-35 and B100) as well as for FAME blends with a commercial EN590. The B7 fuel was used as reference in all measurements. Aged biodiesel (FAME/B100) almost doubled (1.8 times) its separation time compared to the un-aged FAME/B100 sample and had almost three times (2.9) longer phase separationtime relative the reference B7 fuel. Also fuel blends showed long separation times. A fuel blend based on aged FAME/B100 blended with B7 to a corresponding B30 (30% FAME) gave after three consecutive 10 s mixings stable emulsions (>30 min) in two out of three replicates. All fuels blended with commercial EN590 showed excellent phase separation efficiencies with significantly shorter separation times than FAME/B100. We also show that the phase separation efficiency of the B30 blend could be improved after the rape seed ester was vacuum distilled before blending with B7 petrodiesel. The results indicate that likely emulsion problems associated with the B30 blends can be circumvented with proper selection of compatible petroleum components as well as FAME purifications.

  • 28.
    Strömberg, Niklas
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Sahlin, Eskil
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Determination of the short-chain fatty acid pattern in biodiesel using high throughput syringe solvent extraction and ion exclusion chromatography2012Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 97, s. 531-535Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Strömberg, Niklas
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Saramat, Ali
    Scania, Sweden.
    Eriksson, Henrik
    Scania, Sweden.
    Biodiesel degradation rate after refueling2013Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 105, nr Mar, s. 301-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The overall objective of this study was to firmly investigate if the refueling frequency influences the degradation rate of biodiesel and find out if primary and secondary oxidation products can act as initiators for biodiesel degradation in absence of metals. Duplicate samples of B7 Reference fuel Euro VI and B100 methyl rape seed ester were studied during accelerated aging in an open to dry atmosphere system at an elevated temperature (80 °C) during 14 days. Determinations of water, short chain fatty acids as well as structural changes using infrared spectroscopy were used as degradation measures during aging and complemented with total acid number and hydroperoxide concentration at the end of the experiment. The study clearly shows that there are no autocatalytic effects from left over fuel after refueling and thus, the primary and secondary products do not directly influence the degradation rate of the fuel and that the fuel quality are in fact improved after refueling as the remaining degradation products are diluted.

  • 30.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Brackmann, Christian
    Lund University, Sweden.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Mannazhi, Manu
    Lund University, Sweden.
    Simonsson, Johan
    Lund University, Sweden.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Bengtsson, Per Erik
    Lund University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry2019Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 252, s. 125-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this work was to move towards developing a comprehensible Computational Fluid Dynamics (CFD) model to facilitate the predictive modeling of Fast Pyrolysis Oil (FPO) spray combustion. A CFD model was implemented from the literature and results were compared to 2D data from non-intrusive optical diagnostics involving Planar Laser Induced Fluorescence of the OH radical, Mie scattering imaging and two-color pyrometry using a laboratory-scale, CH 4 /air flat-flame with an air-assist atomizer. Furthermore, flame radiation and contributions from graybody sources, chemiluminescence and soot were studied experimentally using emission spectroscopy and Laser Induced Incandescence (LII). Reasonable qualitative agreement was found between experimental and model results in terms of flame structure and temperature. Emission spectroscopy and LII results revealed and confirmed earlier observations regarding the low soot concentration of FPO spray flames; furthermore, it was shown that a significant portion of flame radiation originated from graybody char radiation and chemiluminescence from the Na-content of the FPO. These suggest that the treatment of soot formation might not be important in future computational models; however, the description of char formation and Na chemiluminescence will be important for accurately predicting temperature and radiation profiles, important from the point of e.g., large-scale power applications. Confirmed low soot concentrations are promising from an environmental point of view.

  • 31.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center. University of Miskolc, Hungary.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Vikström, Therese
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Gren, Per
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Spray combustion of biomass fast pyrolysis oil: Experiments and modeling2019Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 237, s. 580-591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime. 

  • 32.
    Villacorta, Edmundo
    et al.
    Western Norway University of Applied Sciences, Norway; Otto von Guericke University, Germany.
    Haraldseid, Ingunn
    Western Norway University of Applied Sciences, Norway; Otto von Guericke University, Germany.
    Fjellgaard Mikalsen, Ragni
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. Western Norway University of Applied Sciences, Norway; Otto von Guericke University, Germany.
    Hagen, Bjarne
    Western Norway University of Applied Sciences, Norway.
    Erland, Sveinung
    Western Norway University of Applied Sciences, Norway.
    Kleppe, Gisle
    Western Norway University of Applied Sciences, Norway.
    Krause, Ulrich
    Otto von Guericke University, Germany.
    Frette, Vidar
    Western Norway University of Applied Sciences, Norway.
    Onset of smoldering fires in storage silos: Susceptibility to design, scenario, and material parameters2021Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 284, artikkel-id 118964Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biomass fuels in large storage units are prone to self-heating and ignition causing smoldering fires. Here, the susceptibility of such ignition processes to parameters is explored through small-scale experiments. In a silo geometry, wood pellets samples of size 0.75 to 1.5 kg were heated from below to initiate smoldering, while the top was open, allowing convective exchange of gases between the porous sample and the surroundings. The thermally insulated sidewalls reduce the heat flow in lateral direction in a similar way that additional pellets material would do in a larger set-up. Thus, the present experimental set-up mimics a much larger system in lateral direction. After heating was terminated, the procedure led to self-sustaining smoldering or spontaneous cooling, depending on parameters. The transition zone between smoldering and non-smoldering was explored under variation in sample size, imposed heating, pellets type, and height of sample container. Logistic regression was applied to fit the experimental data to a model. The model predicted the probability of an experiment to result in either smoldering or non-smoldering under variation in parameters – and the parameters were sorted according to importance. The duration of the external heating was found to be the most influential parameter. For risk assessments in connection with large biomass fuel storage units, this result indicates that the temperature increase could be more important than the size and geometry of the storage unit and the stored material type. © 2020 The Authors

  • 33.
    Wang, Shule
    et al.
    KTH Royal Institute of Technology, Sweden.
    Persson, Henry
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety. KTH Royal Institute of Technology, Sweden.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Jönsson, Pär
    KTH Royal Institute of Technology, Sweden.
    Pyrolysis study of hydrothermal carbonization-treated digested sewage sludge using a Py-GC/MS and a bench-scale pyrolyzer2019Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 262, artikkel-id 116335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The disposal of digested sewage sludge is becoming a global problem. Hydrothermal carbonization (HTC) combined with the pyrolysis of digested sewage sludge was investigated by using a new conversion route for the exploitation of sewage sludge in energy applications. The thermochemical properties of the material were investigated by using HTC pre-treatments, thermogravimetric analyses, pyrolysis tests in Py-GC/MS and a bench-scale fixed bed reactor at temperatures of 450, 550, and 650 °C. It was found that the thermal decomposition of the hydrothermally treated digested sewage sludge takes place in a two-stage reaction. After pyrolysis, the ash in the sample was oxidized in the O2 atmosphere at 900 °C. Therefore, a new characterization method for determination of the non-oxdized ash content and fixed carbon content was proposed. The result from Py-GC/MS shows that the abundance of aromatic hydrocarbons in pyrolytic vapors present a positive correlation with increased temperature. In the bench-scale experiments, the highest HHV of the organic fraction was obtained at 650 °C as 38.46 MJ/kg. 

  • 34.
    Weiland, Fredrik
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center. Luleå University of Technology, Sweden.
    Hedman, Henry
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Wennebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Pettersson, Esbjörn
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    Luleå University of Technology, Sweden.
    Influence of process parameters on the performance of an oxygen blown entrained flow biomass gasifier2015Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 153, s. 510-519Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressurized, O2 blown, entrained flow gasification of pulverized forest residues followed by methanol production is an interesting option for synthetic fuels that has been particularly investigated in the Nordic countries. In order to optimize gasification plant efficiency, it is important to understand the influence of different operating conditions. In this work, a pressurized O2 blown and entrained flow biomass gasification pilot plant was used to study the effect of four important process variables; (i) the O2 stoichiometric ratio (λ), (ii) the load of the gasifier, (iii) the gasifier pressure, and (iv) the fuel particle size. Commercially available stem wood fuels were used and the process was characterized with respect to the resulting process temperature, the syngas yield, the fuel conversion and the gasification process efficiency. It was found that CH4 constituted a significant fraction of the syngas heating value at process temperatures below 1400 °C. If the syngas is intended for catalytic upgrading to a synthetic motor fuel where CO and H2 are the only important syngas species, the process should be optimized aiming for a process temperature slightly above 1400 °C in order to reduce the energetic losses to CH4 and C6H6. This resulted in a cold gas efficiency (based only on CO and H2) of 70%. The H2/CO ratio was experimentally determined within the range 0.45-0.61. Thus, the syngas requires shifting in order to increase the syngas composition of H2 prior to fuel synthesis.

  • 35.
    Wiinikka, Henrik
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Bostrom, D.
    Ohman, M.
    Influence of fuel ash composition on high temperature aerosol formation in fixed bed combustion of woody biomass pellets2007Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 86, s. 181-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the influence of fuel ash composition on high temperature aerosol formation during fixed bed combustion of woody biomass (two wood pellets and one bark pellets) were investigated experimentally in a laboratory reactor and theoretically through chemical equilibrium model calculations. For all fuels, the particle mass size distribution in the PM2.5 region was bimodal, with one fine mode and one coarse mode. Early in the flame, the fine mode was dominated by particles from incomplete combustion and these particles were rapidly oxidised in the post flame zone. After the hot flame, the fine mode concentration and the particle diameter increases gradually when the temperature decreases due to condensation of vaporised inorganic matter, K, Na, S, Cl, and Zn. For two of the fuels also P could be found in the fine particles. The coarse mode consisted of carbon, refractory metals and considerable amount of alkali. Further, the initial fuel alkali concentration and the alkali to silicon ratio (K + Na)/Si influenced the amount of vaporised aerosol forming alkali matter. Finally, the present study shows that, combustion temperature and fuel ash composition is of major importance for the formation of high temperature aerosols in fixed bed combustion of woody biomass pellets. © 2006 Elsevier Ltd. All rights reserved.

  • 36.
    Wiinikka, Henrik
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Johansson, Ann-Christine
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Öhrman, Olov G.W.
    RISE - Research Institutes of Sweden, Bioekonomi, ETC Energy Technology Center.
    Fate of inorganic elements during fast pyrolysis of biomass in a cyclone reactor2017Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 203, s. 537-547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to reduce ash related operational problem and particle emissions during pyrolysis oil combustion it is important to produce pyrolysis oil with very low concentration of inorganics. In this paper, the distribution of all major inorganic elements (S, Si, Al, Ca, Fe, K, Mg, Mn, Na, P, Ti and Zn) in the pyrolysis products (solid residue and two fractions of pyrolysis oil) was investigated during pyrolysis of stem wood, bark, forest residue, salix and reed canary grass. The raw materials were pyrolysed in a cyclone reactor and the produced pyrolysis oils were recovered as two oil fractions, a condensed fraction and an aerosol fraction. The inorganic composition of the ingoing raw material, the solid residue and the two pyrolysis oil fractions were analysed with inductively coupled plasma spectrometry techniques. All major inorganic elements, except sulphur, were concentrated in the solid residue. A significant amount of sulphur was released to the gas phase during pyrolysis. For zinc, potassium and iron about 1–10 wt% of the ingoing amount, depending on the raw material, was found in the pyrolysis oil. For the rest of the inorganics, generally less than 1 wt% of the ingoing amount was found in the pyrolysis oil. There were also differences in distribution of inorganics between the condensed and the aerosol oil fractions. The easily volatilized inorganic elements such as sulphur and potassium were found to a larger extent in the aerosol fraction, whereas the refractory elements were found to a larger extent in the condensed fraction. This implies that oil fractionation can be a method to produce oil fractions with different inorganic concentrations which thereafter can be used in different technical applications depending on their demand on the inorganic composition of the pyrolysis oil.

  • 37.
    Zhao, Z.
    et al.
    Wuhan University, China.
    Qin, H.
    Hubei University of Economics, China.
    Li, Tian
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet. NTNU, Norway.
    Hua, B.
    Wuhan University, China.
    Hou, Y.
    Wuhan University, China.
    Chen, T.
    Wuhan University, China.
    Ström, H.
    NTNU, Norway; Chalmers University of Technology, Sweden.
    CFD simulation of soot generation during biomass gasification in a cyclone gasifier2024Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 364, artikkel-id 131103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soot generation is a challenging issue in high-temperature biomass gasification, which reduces the biomass conversion rate and leads to contamination of the reactor. To provide new means and insights to optimize gasification processes, the soot generation during biomass gasification in a cyclone reactor is studied here by establishing a novel biomass gasification and soot formation model to improve the accuracy attainable in numerical predictions of spatio-temporal soot evolution. The new method is validated by comparing it with gasification experiments in two reactor configurations. A good performance in capturing the overall soot generation and light gas yield of the current model is obtained in the simulations of an entrained flow reactor compared with experimental data. Besides, the biomass gasification behavior in this entrained flow reactor is systematically studied by reviewing the tar, precursor, and soot mass fraction evolution in the reactor under different steam/carbon ratios, gasification temperatures, and air excess ratios with the new model. Furthermore, the influence of varying air equivalence ratios, the operation temperature and the fuel moisture on the soot generation in a cyclone gasifier, as well as the ability of the proposed model to reflect such influences, are also discussed. Numerical simulations demonstrate the existence of an optimal operation condition for the cyclone gasifier in terms of the soot generation. The current work thus provides a useful tool for analyzing the mechanism of soot formation at the reactor scale. 

  • 38.
    Zhu, G.
    et al.
    Xi’an Jiaotong University, China.
    Xu, L.
    Xi’an Jiaotong University, China.
    Wang, S.
    Xi’an Boiler & Environmental Protection Engineering Co Ltd, China; Xi’an Jiaotong University, China.
    Niu, F.
    China Coal Research Institute Company of Energy Conservation, China.
    Li, Tian
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet. NTNU, Norway.
    Hui, S.
    Xi’an Jiaotong University, China.
    Niu, Y.
    Xi’an Jiaotong University, China.
    Synergistic reduction on PM and NO source emissions during preheating-combustion of pulverized coal2024Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 361, artikkel-id 130699Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present research focuses on the synergistic source control of particulate matter (PM) and NOx formation from pulverized coal combustion. Comparative experiments of preheating-combustion and conventional combustion were conducted in a lab-scale high-temperature preheating-combustion furnace, and PM10 and NO were measured by an electrical low pressure impactor and a flue gas analyzer, respectively. The results of the experiment indicate that preheating-combustion has a significant reduction in PM10 (especially PM0.3 up to 37.51 %) and NO, which can achieve the synergistic control of PM10 and NO source emissions during the combustion process. The fragmentation in preheating-combustion was weaker compared to the conventional combustion. Meanwhile, the relatively weak preheating-combustion coal char oxidation reaction leads to a decrease in ultrafine mode PM yielded due to the inhibition on vaporization of mineral inclusions. The PM0.3/PM1 mass ratio of the preheating-combustion has a decreasing trend, implying an elevated yield of PM0.3-1 and a shift of the average PM1 particle size toward a larger particle size. Higher preheating temperature (Tp) presented the potential to further reduce NO formation, and the NO reduction efficiency increased from 46.59 % to 56.60 % when the Tp was increased from 1200 K to 1600 K. All our preliminary results throw light on the nature of synergistic source control of preheating-combustion PM and NO formation. 

  • 39.
    Öhrman, Olov .G.W
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Häggström, Caroline
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedlund, Jonas L.L.
    Luleå University of Technology, Sweden.
    Gebart, Rikard
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Analysis of trace components in synthesis gas generated by black liquor gasification2012Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 102, s. 173-179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The only pressurized black liquor gasifier currently in operation is located in Sweden. The composition of the main components in the gas has been reported previously. The main components are H 2, CO, CO 2, N 2, CH 4, and H 2S. In the present work, trace components in the gas have been characterized and the results are hereby reported for the first time. Samples were taken at two occasions during a one year period. The benzene concentration in the gas varied only slightly and the average concentration was 158 ppm. Benzene is formed by thermal cracking of the biomass. The COS concentration varied substantially and the average concentration was 47 ppm. The variations may be related to how the quench is operated. A few ppm of C 2-hydrocarbons were also observed in the gas and the variation was probably a result of varying oxygen to black liquor ratio. No tars were observed in the gas. However, tar compounds, such as phenanthrene, pyrene, fluoranthene and fluorene were detected in deposits found on the pipe walls after the gas cooler. The concentration of particles in the synthesis gas was very low; <0.1 mg/N m 3, which is comparable to the particulate matter in ambient air. Submicron particles were comprised of elements such as C, O, Na, Si, S, Cl, K, and Ca, and these particles probably originated from the black liquor. Larger particles were comprised mainly of Fe, S and Ni and these particles probably resulted from corrosion of steel in the plant pipe-work. In summary, the concentrations of trace components and particles in the gas are quite low.

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