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Numrering	Referens	Omslagsbild	Hitta
1.	Proceedings of the 2010 Winter Simulation Conference 2010 Samlingsverk (redaktörskap) (refereegranskat)
2.	Systems Perspectives on Biorefineries 2013 2013 Samlingsverk (redaktörskap) (refereegranskat)abstract Replacing fossil fuels with biomass for the production of energy carriers, materialsand specialty chemicals is a challenge that now confronts humanity. In whichapplications shall we use limited resources of biomass? How can biomass berefined into the products we want? What are the consequences of demanding toomuch? What is an optimal design of a biorefinery? Where should they be located?What policy instruments are required to realise the biorefineries of the future?There is not one final answer to these questions. However, different systems studiescan provide us with complementary pieces of the puzzle. These can be valuableby themselves, or be brought together into a larger and more complex picture.Systems Perspectives on Biorefineries 2013 is an updated edition of SystemsPerspectives on Biorefineries 2012 and contains twelve chapters that address differenttopics related to the immensely important issue of how the world’s biomassresources can, or should, be converted into the goods we need and desire. Thebook is still far from complete, but it is a contribution and a start...
3.	Brandin, Jan, 1958-, et al. (författare) Multi-function catalysts for glycerol upgrading 2010 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract During the last three years Biofuel-Solution, a privately held Swedish entity, has developed an IP-portfolio around gas-phase glycerol conversion into medium-value chemicals. The targeted chemicals have large to very large markets, to allow for use by more than a fraction of the glycerol available today without impacting the cost of the product. The reason behind is that glycerol is a by-product from the biofuel industry, including biodiesel and bioethanol. This indicates large production volumes, even though the glycerol is a fraction of the fuel produced. A by-product from any fuel process will be vast and therefore any chemical produced from this side-product will have to have a large market to offset it to. In order to avoid changing the fundamental market behavior, similar to what the biodiesel industry has done to the glycerol market. In the course of this work, several end-products have been targeted. These include plastic monomers, mono-alcohols and energy gases; using acrolein as a common starting point. To produce chemicals with high purity and efficiency, selective and active catalysts are required. For instance, a process for producing propionaldehyde and n-propanol has been developed to the point of demonstration and commercialization building on the gas-phase platform. By developing multi-function catalysts which perform more than one task simultaneously, synergies can be reached that cannot be achieved with traditional catalysts. For instance, by combining catalyst functionalities, reactions that are both endothermic and exothermic can be performed simultaneously. This mean lower inlet reactor temperatures (in this particular case) and a more even temperature distribution. By performing the dehydration of glycerol to acrolein in combination with another, exothermal reaction by-products can be suppressed and yields increased. It also means that new reaction pathways can be achieved, allowing for new ways to produce chemicals and fuels from glycerol. As in the case of ethane production from acrolein, where a catalyst surface has been devised where acrolein is first adsorbed. The actual mechanism is unknown but in speculation, the adsorbed acrolein is decarbonyled into ethylene and carbon monoxide on a first reaction site. The formed carbon monoxide diffuses to another active site, where it reacts with water through the so called water-gas shift reaction to carbon dioxide and hydrogen. Said carbon dioxide leaves as an end-product, and the hydrogen diffuses to another active site where it reacts with ethylene to form ethane. This gives a way of producing energy gases from glycerol in a very compact reactor set-up, effectively reducing footprint and capital cost and increasing productivity of an installation.
4.	Eriksson, Gunnar, et al. (författare) Combustion and fuel characterisation of wheat distillers dried grain with solubles (DDGS) and possible combustion applications 2012 Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 102, s. 208-220 Tidskriftsartikel (refereegranskat)abstract The present transition to a sustainable global energy system requires that biomass is increasingly combusted for heat and power production. Agricultural fuels considered include alkali-rich fuels with high phosphorus content. One such fuel is wheat distiller’s dried grain with solubles (wheat DDGS) from wheat-based ethanol production. Further increases in ethanol production may saturate the current market for wheat DDGS as livestock feed, and fuel uses are therefore considered. Fuel properties of wheat DDGS have been determined. The ash content (5.4 ± 1.6 %wt d.s.) is similar to many agricultural fuels. In comparison to most other biomass fuels the sulphur content is high (0.538 ± 0.232 %wt d.s.), and so are the contents of nitrogen (5.1 ± 0.6 %wt d.s.), phosphorus (0.960. ± 0.073 %wt d.s.) and potassium (1.30 ± 0.35 %wt d.s.). To determine fuel-specific combustion properties, wheat DDGS and mixes between wheat DDGS and logging residues (LR 60 %wt d.s. and DDGS 40 %wt d.s.), and wheat straw (wheat straw 50 %wt d.s., DDGS 50 %wt d.s.) were pelletized and combusted in a bubbling fluidised bed combustor (5 kW) and in a pellets burner combustor (20 kW). Pure wheat DDGS powder was also combusted in a powder burner (150 kW). Wheat DDGS had a high bed agglomeration and slagging tendency compared to other biomass fuels, although these tendencies were significantly lower for the mixture with the Ca-rich LR, probably reflecting the higher first melting temperatures of K–Ca/Mg-phosphates compared to K-phosphates. Combustion and co-combustion of wheat DDGS resulted in relatively large emissions of fine particles (<1 μm) for all combustion appliances. For powder combustion PMtot was sixteen times higher than from softwood stem wood. While the Cl concentrations of the fine particles from the the mixture of LR and wheat DDGS in fluidised bed combustion were lower than from combustion of pure LR, the Cl- and P-concentrations were considerably higher from the wheat DDGS mixtures combusted in the other appliances at higher fuel particle temperature. The particles from powder combustion of wheat DDGS contained mainly K, P, Cl, Na and S, and as KPO3 (i.e. the main phase identified with XRD) is known to have a low melting temperature, this suggests that powder combustion of wheat DDGS should be used with caution. The high slagging and bed agglomeration tendency of wheat DDGS, and the high emissions of fine particles rich in K, P and Cl from combustion at high temperature, mean that it is best used mixed with other fuels, preferably with high Ca and Mg contents, and in equipment where fuel particle temperatures during combustion are moderate, i.e. fluidised beds and possibly grate combustors rather than powder combustors.
5.	Method and models used in the project Pathways to Sustainable European Energy Systems 2011 Samlingsverk (redaktörskap) (refereegranskat)abstract This book describes the research that has been carried out during the first period (2006-2010) of the Alliance for Global Sustainability (AGS) project "Pathways to Sustainable European Energy Systems". this interdisciplinary project involves more that 40 researchers and addresses various aspects of the challenges faced in transforming the European energy system. Presented in this book are the energy-related methods and models that originate from different scientific disciplines and traditions and that were applied in the Pathways project. Some of the analytical tools are well-known, well-documented, and widely used in academic research. Others have been developed (or refined) during the Pathways project and are therefore unique. The chapters of this book cover around 30 different methods and models used in the Pathways project and presents an overview of the processes through which the research was conducted and the methods and models were co-ordinated.
6.	Shwan, Soran, 1984 (författare) Metal-exchanged zeolites for NH3-SCR applications - Activity and Deactivation studies 2014 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Emissions of nitrogen oxides (NOX) formed during the burning process in internal combustion engines is a major contributor to global air pollutions. One effective way to reduce NOX in lean environments, i.e. oxygen excess is selective catalytic reduction with ammonia (NH3-SCR). Metal-exchanged zeolites have proven to be active as SCR catalysts, where copper and iron are the most common metals. When using metal-exchanged zeolites in exhaust aftertreatment systems, several challenges arise. Resistance towards hydrothermal deactivation and chemisorption of impurities on the active sites of the catalyst are two of the more important challenges. Temperatures between 600-700oC can be seen during regeneration of the particulate filter, which usually is placed upstream close to the SCR catalyst in the exhaust aftertreatment system, and therefore hydrothermal stability of the metal-exchanged zeolite is crucial. Furthermore, high tolerance against catalyst poisons which originate from (bio-) fuels and lubricating oils is desired, where phosphorous and potassium are among the more important poisons. In this thesis thermal and chemical deactivation of iron-exchanged zeolite BEA as SCR catalyst is experimentally studied with special focus paid on the active iron species. Based on the experimental results a kinetic model is developed to predict the decreased activity of the catalyst after deactivation. Several characterization techniques are used to evaluate and correlate structural changes in the catalyst with the decreased activity. Catalysts are prepared and characterized using BET, XPS, XRD, TPD, in-situ FTIR and UV-Vis. The catalytic performance of the samples is measured using a flow-reactor system.It is concluded that the hydrothermal deactivation of Fe-BEA is a result of migration of isolated iron species forming iron cluster inside the zeolite pores and iron particles located on the external surface of the zeolite crystals. Further, it is shown that the growth of iron clusters and particles can be partially reversed by high temperature hydrogen treatment. The chemical deactivation due to phosphorous exposure is the result of formation of metaphosphates replacing hydroxyl groups on the active isolated iron species. Furthermore, the chemical deactivation of Fe-BEA by potassium is concluded to be due to exchange and loss of active isolated iron species in the zeolite forming smaller iron clusters inside the zeolite pores.A kinetic model where different iron species are included was developed based on the hydrothermal deactivation experiments and validated using phosphorous and potassium exposed samples. By fitting and fix the kinetic parameters towards a fresh sample, the decreased SCR activity can be predicted by just decreasing the number of active iron sites, representing loss of active iron species due to hydrothermal treatment and poisoning.The effect of gas atmosphere during solid-state ion-exchange of copper-zeolites was studied as well. It is concluded that copper becomes highly mobile due to formation of copper-ammine complexes in presence of NH3 after reduction of CuII to CuI by adding NO in the exposing gas during the solid-state ion-exchange. Copper-exchanged zeolites could be prepared by exposing physical mixtures of copper-oxides with zeolites to NO and NH3 at as low temperature as 250oC.Finally, the ammonia formation during the rich period of NOX storage and reduction (NSR) cycles was studied using kinetic modeling for the possibility of combining NSR and SCR catalysts in the exhaust aftertreatment system. It is concluded that the formation of ammonia is due to stored NOX and hydrogen from the gas in the first half of the catalyst. However, it was further concluded that the formation of ammonia is delayed due to formation of N2O from stored NOX and formed NH3.
7.	Halvarsson, Sören, 1956- (författare) Manufacture of straw MDF and fibreboards 2010 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract The purpose of this thesis was to develop an economical, sustainable, and environmentally friendly straw Medium Density Fibreboard (MDF) process, capable of full-scale manufacturing and to produce MDF of requested quality. The investigated straw was based on wheat (Triticum aestivum L.) and rice (Oryzae sativa L.). In this thesis three different methods were taken for manufacture of straw MDF; (A) wheat-straw fibre was blowline blended with melamine-modified urea-formaldehyde (MUF), (B) rice-straw fibre was mixed with methylene diphenyl diisocyanate (MDI) in a resin drum-blender, and (C) wheat-straw fibre was activated in the blowline by the addition of Fenton’s reagent (H2O2/Fe2+) for production of non-resin MDF panels. The MUF/wheat straw MDF panels were approved according to the requirements of the EN standard for MDF (EN 622-5, 2006). The MDI/rice-straw MDF panels were approved according to requirements of the standard for MDF of the American National Standard Institute (ANSI A208.2-2002). The non-resin wheat-straw panels showed mediocre MDF panel properties and were not approved according to the requirements in the MDF standard. The dry process for wood-based MDF was modified for production of straw MDF. The straw MDF process was divided into seven main process steps. 1. Size-reduction (hammer-milling) and screening of straw 2. Wetting and heating of straw 3. Defibration 4. Resination of straw fibre 5. Mat forming 6. Pre-pressing 7. Hot-pressing The primary results were that the straw MDF process was capable of providing satisfactory straw MDF panels based on different types of straw species and adhesives. Moreover, the straw MDF process was performed in pilot-plant scale and demonstrated as a suitable method for producing straw MDF from straw bales to finished straw MDF panels. In the environmental perspective the agricultural straw-waste is a suitable source for producing MDF to avoid open field burning and to capture carbon dioxide (CO2), the biological sink for extended time into MDF panels, instead of converting straw directly into bio energy or applying straw fibre a few times as recycled paper. Additionally, the straw MDF panels can be recycled or converted to energy after utilization. A relationship between water retention value (WRV) of resinated straw fibres, the thickness swelling of corresponding straw MDF panels, and the amount of applied adhesive was determined. WRV of the straw fibre increased and the TS of straw MDF declined as a function of the resin content. The empirical models developed were of acceptable significance and the R2 values were 0.69 (WRV) and 0.75 (TS), respectively. Reduced thickness swelling of MDF as the resin content is increased is well-known. The increase of WRV as a function of added polymers is not completely established within the science of fibre swelling. Fortunately, more fundamental research can be initiated and likely a simple method for prediction of thickness swelling of MDF by analysis of the dried and resinated MDF fibres is possible.
8.	Heyne, Stefan, 1979 (författare) Bio-SNG from Thermal Gasification - Process Synthesis, Integration and Performance 2013 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Biomethane or synthetic natural gas (Bio-SNG) produced from gasified renewable woody biomass is a promising option for replacing fossil natural gas. The complete interchangeability with natural gas in all its conventional applications such as in the power generation, transportation and chemical industry sector is of particular interest.This work presents results from a comprehensive process integration study of different process alternatives for Bio-SNG production from gasified biomass. The influence of the main conversion steps in the process chain – drying, gasification, gas cleaning, methanation, and gas upgrade – on the overall process performance is investigated. Process bottlenecks and both heat and material integration opportunities are highlighted. Using future energy market scenarios the energetic, economic, and carbon footprint performance of the investigated processes are evaluated from a system perspective clearly showing the sensitivity of the obtained results to underlying assumptions.It is shown that drying of the biomass feedstock prior to gasification using excess process heat – using steam drying or low-temperature air drying technology – is an important aspect for improving the process energy efficiency. The results also indicate that indirect and direct gasification technologies perform equally well within the overall Bio-SNG production process. Existing infrastructure in the form of biomass-fired combined heat and power plants based on fluidised bed combustion technology presents interesting opportunities for integrating indirect gasification for Bio-SNG production, with beneficial effects on the cogeneration of electricity from the Bio-SNG process excess heat. The choice of methanation technology between fixed and fluidised bed is not a critical one with respect to process integration, since both technologies allow for efficient heat recovery and consequent cogeneration. For gas upgrade, in particular removal of CO2 from the product gas, amine based separation is shown to achieve better energy efficiency and economic performance than membrane based or pressure swing adsorption processes. Preliminary estimations of Bio-SNG costs are significantly higher than current natural gas prices, thus dedicated and long term policy measures are necessary in order to stimulate Bio-SNG production. The process integration aspects presented in this thesis can contribute to reducing production costs by increasing energy efficiency and in consequence increasing economic robustness of Bio-SNG process concepts.
9.	European Energy Pathways - Pathways to sustainable european energy systems 2011 Samlingsverk (redaktörskap) (refereegranskat)abstract To meet the challenge of climate change, the world must substaintially reduce emissions of greenhouse gases (GHGs). this must be accomplished in a way that maintains security of supply and competitiveness.This book presents to pathways towards sustainable European energy systems - the "Policy Pathway" and the "Market Pathway". These to pathways differ with respect to where the main responsability lies for transforming the energy system in following the pathway. The Policy pathway takes its departure from the EU Energy and Climate Package, and has a strong focus on targeted policies that promote energy efficiency and energy from renewable sources. The Market Pathway relies more on the market to transform the energy system, and presents a future in which the cost associated with emitting CO2 (and other GHGs) is the dominating policy measure.This book describes the research that has been carried out during the first period (2006-2010) of the AGS project "Pathways to Sustsainable Energy Systems". This interdisciplinary project involved more than 40 researchers and addressed various aspects of the challenges faced in transforming the European energy system. The chapters in this book cover more than 30 topics and presents an overall picture of the results obtained to date from various activities in the Pathways project.
10.	Bylin, Susanne, 1982 (författare) Mechanisms of Biopolymer Solvation: Development of a two-component ionic liquid solvent system 2014 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Ionic liquids are of potential interest in the processing of lignocellulosic biomass, and/or its components, for the purpose of producing renewable and value-added biomaterials. An understanding of how solvation can be achieved and the way in which the feedstock biopolymers are affected, however, needs to be gained prior to a viable implementation. In this thesis, the solvation of the wood biopolymers cellulose, xylan and lignin in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIMAc) in a novel combination with the second system component 1-methylimidazole (MIM) have been investigated:The solvation of dissolving pulp, beech xylan and LignoBoost lignin model materials, was studied using FBRM (focused beam reflectance measurements) particle characterization in combination with microscopic analysis (cellulose and xylan), determination of molecular weights (xylan and lignin) and 13C- and 31P-NMR (nuclear magnetic resonance spectroscopy) of lignin.It was concluded that the most efficient solvation of cellulose and xylan occurred using 3-4% and 9% IL (n/n anhydroglucose units and n/n anhydroxylose Units), respectively, while polymer integrity was maintained. Cellulose solvation was found to be greatly dependent on the IL to AGU ratio whereas xylan solvation varied greatly with temperature. Moreover, a theoretical model was developed for the solvation of cellulose in the present system. The solvation of lignin was achieved at ~20% lignin loading (w/w), in any combination of MIM/EMIMAc. Regeneration of lignin resulted in two sets of fractions; one exhibiting a general and higher apparent molecular weight (Mw) along with an enrichment of condensed/aliphatic ether linkages and aliphatic hydroxyls, and the other exhibiting a lower apparent Mw and an enrichment of carboxylic and phenolic groups. The knowledge of biopolymer solvation gained in the present solvent system provides future opportunities of tuning extraction and/or fractionation processes to suite the specifications of a particular biomass-derived product.
11.	Ström, Henrik, 1981, et al. (författare) DNS of dispersed multiphase flows with heat transfer and rarefaction effects 2014 Ingår i: Journal of Computational Multiphase Flows. - 1757-482X .- 1757-4838. ; 6:3, s. 193-206 Tidskriftsartikel (refereegranskat)abstract We propose a method for DNS of particle motion in non-isothermal systems. The method uses a shared set of momentum and energy balance equations for the carrier- and the dispersed phases. Measures are taken to ensure that non-deformable entities (solid particles) behave like rigid bodies. Moreover, deformable entities (e.g. bubbles) as well as rarefaction effects can be accommodated. The predictions of the method agree well with the available data for isothermal solid particles motion in the presence of walls and other particles, natural convection around a stationary particle, solid particles motion accompanied with heat transfer effects and isothermal solid particles motion under rarefied conditions. The method is used to investigate the simultaneous effects of heat transfer and rarefaction on the motion of a solid catalyst particle in an enclosure, the interaction of a solid particle and a microbubble in a flotation cell and a case with more than 1000 particles.
12.	Bracewell, Daniel, et al. (författare) Report and recommendation of a workshop on education and training for measurement, monitoring, modelling and control ((MC)-C-3) in biochemical engineering 2010 Ingår i: Biotechnology Journal. - : Wiley-VCH Verlagsgesellschaft. - 1860-6768 .- 1860-7314. ; 5:4, s. 359-367 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
13.	Lindgren, Mikaela, 1987, et al. (författare) Confinement dependence of electro-catalysts for hydrogen evolution from water splitting 2014 Ingår i: Beilstein Journal of Nanotechnology. - : Beilstein Institut. - 2190-4286. ; 5:1, s. 195-201 Tidskriftsartikel (refereegranskat)abstract Density functional theory is utilized to articulate a particular generic deconstruction of the electrode/electro-catalyst assembly for the cathode process during water splitting. A computational model was designed to determine how alloying elements control the fraction of H2 released during zirconium oxidation by water relative to the amount of hydrogen picked up by the corroding alloy. This model is utilized to determine the efficiencies of transition metals decorated with hydroxide interfaces in facilitating the electro-catalytic hydrogen evolution reaction. A computational strategy is developed to select an electro-catalyst for hydrogen evolution (HE), where the choice of a transition metal catalyst is guided by the confining environment. The latter may be recast into a nominal pressure experienced by the evolving H2 molecule. We arrived at a novel perspective on the uniqueness of oxide supported atomic Pt as a HE catalyst under ambient conditions.
14.	Nilsson, Helena, et al. (författare) Compression molded wood pulp biocomposites : A study of hemicellulose influence on cellulose supramolecular structure and material properties 2012 Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 19:3, s. 751-760 Tidskriftsartikel (refereegranskat)abstract In this study, the importance of hemicellulose content and structure in chemical pulps on the property relationships in compression molded wood pulp biocomposites is examined. Three different softwood pulps are compared; an acid sulfite dissolving grade pulp with high cellulose purity, an acid sulfite paper grade pulp and a paper grade kraft pulp, the latter two both containing higher amounts of hemicelluloses. Biocomposites based the acid sulfite pulps exhibit twice as high Young's modulus as the composite based on paper grade kraft pulp, 11-12 and 6 GPa, respectively, and the explanation is most likely the difference in beating response of the pulps. Also the water retention value (WRV) is similarly low for the two molded sulfite pulps (0.5 g/g) as compared to the molded kraft pulp (0.9 g/g). The carbohydrate composition is determined by neutral sugar analysis and average molar masses by SEC. The cellulose supramolecular structure (cellulose fibril aggregation) is studied by solid state CP/MAS 13C-NMR and two forms of hemicellulose are assigned. During compression molding, cellulose fibril aggregation occurs to higher extent in the acid sulfite pulps as compared to the kraft pulp. In conclusion, the most important observation from this study is that the difference in hemicellulose content and structure seems to affect the aggregation behaviour and WRV of the investigated biocomposites.
15.	Wetterlund, Elisabeth, et al. (författare) Implications of system expansion for the assessment of well-to-wheel CO2 emissions from biomass-based transportation 2010 Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 34:13, s. 1136-1154 Tidskriftsartikel (refereegranskat)abstract In this paper we show the effects of expanding the system when evaluating well-to-wheel (WTW) CO2 emissions for biomass-based transportation, to include the systems surrounding the biomass conversion system. Four different cases are considered: DME via black liquor gasification (BLG), methanol via gasification of solid biomass, lignocellulosic ethanol and electricity from a biomass integrated gasification combined cycle (BIGCC) used in a battery-powered electric vehicle (BPEV). All four cases are considered with as well as without carbon capture and storage (CCS). System expansion is used consistently for all flows. The results are compared with results from a conventional WTW study that only uses system expansion for certain co-product flows. It is shown that when expanding the system, biomass-based transportation does not necessarily contribute to decreased CO2 emissions and the results from this study in general indicate considerably lower CO2 mitigation potential than do the results from the conventional study used for comparison. It is shown that of particular importance are assumptions regarding future biomass use, as by expanding the system, future competition for biomass feedstock can be taken into account by assuming an alternative biomass usage. Assumptions regarding other surrounding systems, such as the transportation and the electricity systems are also shown to be of significance. Of the four studied cases without CCS, BIGCC with the electricity used in a BPEV is the only case that consistently shows a potential for CO2 reduction when alternative use of biomass is considered. Inclusion of CCS is not a guarantee for achieving CO2 reduction, and in general the system effects are equivalent or larger than the effects of CCS. DME from BLG generally shows the highest CO2 emission reduction potential for the biofuel cases. However, neither of these options for biomass-based transportation can alone meet the needs of the transport sector. Therefore, a broader palette of solutions, including different production routes, different fuels and possibly also CCS, will be needed.
16.	Lindgren, Mikaela, 1987, et al. (författare) On the fate of hydrogen during zirconium oxidation by water: Effect of oxygen dissolution in α-Zr 2014 Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:22, s. 11050-11058 Tidskriftsartikel (refereegranskat)abstract Zirconium oxidation by water is accompanied by hydrogen conversion, either H2 is released or hydrogen is picked up by the alloy. Strategies are sought to mitigate the detrimental hydrogen uptake into the metal. The corrosion phenomenon is subdivided into anode and cathode processes caused by electron release upon O2- oxidation at the metal/oxide interface in case of the former and electron-proton recombination resulting in hydrogen pick-up or H2 evolution in case of the latter. In a previous study, the additive dependence of the cathodic hydrogen evolution reaction was analysed. The present study contributes the oxygen concentration dependence of the anode potential, presents the impact of oxygen concentration on the co-absorption of hydrogen and merges the anode and cathode processes. The computational model is validated by semi-quantitatively reproducing the experimental solubility limit for oxygen in α-Zr. The impact of the emerging conceptual understanding for material development is discussed.
17.	Grip, Carl-Erik, et al. (författare) Possibilities and problems in using exergy expressions in process integration 2011 Ingår i: Proceedings of the World Renewable Energy Congress 2011 (WREC 2011), 9-13 May, Linköping.. - Linköping : Linköping University Electronic Press. ; , s. 1605-1612 Konferensbidrag (refereegranskat)abstract Industrial energy systems are complicated networks, where changes in one process influence its neighboring processes. Saving energy in one unit does not necessarily lead to energy savings for the total system. A study has been carried out on the possibility to use the exergy concept in the analysis of industrial energy systems. The exergy concept defines the quality of an amount of energy in relation to its surrounding, expressing the part that could be converted into work. The study consists of literature studies and general evaluations, an extensive case study and an interview study. In the latter it was found that non technical factors are major obstacles to the introduction of exergy.
18.	Heyne, Stefan, 1979, et al. (författare) Exergy-based comparison of indirect and direct biomass gasification technologies within the framework of bio-SNG production 2013 Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 3:4, s. 337-352 Tidskriftsartikel (refereegranskat)abstract Atmospheric indirect steam-blown and pressurised direct oxygen-blown gasification are the two major technologies discussed for large-scale production of synthetic natural gas from biomass (bio-SNG) by thermochemical conversion. Published system studies of bio-SNG production concepts draw different conclusions about which gasification technology performs best. In this paper, an exergy-based comparison of the two gasification technologies is performed using a simplified gasification reactor model. This approach aims at comparing the two technologies on a common basis without possible bias due to model regression on specific reactor data. The system boundaries include the gasification and gas cleaning step to generate a product gas ready for subsequent synthesis. The major parameter investigated is the delivery pressure of the product gas. Other model parameters include the air-to-fuel ratio for gasification as well as the H2/CO ratio in the product gas. In order to illustrate the thermodynamic limits and sources of efficiency loss, an ideal modelling approach is contrasted with a model accounting for losses in, e.g. the heat recovery and compression operations. The resulting cold-gas efficiencies of the processes are in the range of 0.66–0.84 on a lower heating value basis. Exergy efficiencies for the ideal systems are from 0.79 to 0.84 and in the range of 0.7 to 0.79 for the systems including losses. Pressurised direct gasification benefits from higher delivery pressure of the finished gas product and results in the highest exergy efficiency values. Regarding bio-SNG synthesis however, a higher energetic and exergetic penalty for CO2 removal results in direct gasification exergy efficiency values that are below values for indirect gasification. No significant difference in performance between the technologies can be observed based on the model results, but a challenge identified for process design is efficient heat recovery and cogeneration of electricity for both technologies. Furthermore, direct gasification performance is penalised by incomplete carbon conversion in contrast to performance of indirect gasification concepts.
19.	Sjöblom, Jonas, 1968, et al. (författare) Experimental validation of particulate matter (PM) capture in open substrates 2014 Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:9, s. 3749-3752 Tidskriftsartikel (refereegranskat)abstract The capture of engine-borne particulate matter (PM) in after-treatment systems is a complex process. Because of the intrinsic heterogenic nature of the PM, the particles undergo transformations that make it very difficult to isolate their motion and deposition in experiments. In a previous study, a model for hydrocarbons (HC) evaporation of the particles during the capture process was proposed to explain experimental results that showed a significant increase in the capture efficiency when compared to those predicted from theoretical models [J. Sjöblom and H. Ström, Ind. Eng. Chem. Res. 2013, 52, 8373]. In this work, inert NaCl particles were fed to an open substrate (cordierite monolith). It was demonstrated that the capture efficiency can be experimentally observed, isolated from other experimental phenomena and uncertainties, if the particles are truly inert. Consequently, the previously proposed model for HC evaporation is a valid starting point for development of comprehensive models for PM motion and transformations.
20.	Tomani, Per, et al. (författare) Lignin removal from different black liquors 2012 Ingår i: 2012 TAPPI PEERS Conference. - 9781622768448 ; , s. 835-843 Konferensbidrag (refereegranskat)abstract Pulp mill biorefining is still a relatively young area in modern pulping R&D driven by megatrends such as increased costs for fossil oil and wood, but also increased competition on the pulp market. The need for new revenues is obvious if the pulp and paper industry is to maintain its strong position. Biorefining can simplified be defined as the efforts to reach as complete utilization of wood raw material as possible in a pulp mill to reach as high revenues as possible. A pulp mill producing chemical pulp is for several reasons an excellent an industrial platform for biorefining. The chemical pulp mill is able to produce relatively pure cellulose, hemicellulose and lignin. The focus in this paper is on separation of lignin from different types of black liquors, the behavior of these black liquors when they are treated according to the LignoBoost concept which we in this paper refer to as "The lignin separation process". Some properties of the separated lignin will also be briefly discussed. "The lignin separation process" is used to remove lignin from kraft/soda black liquors and it has been developed in cooperation between Innventia and Chalmers University of Technology. The technology was sold to Metso Power 2008 and it is now commercially available. Lignin separation, purification, modification and applications have a high priority in R&D work at our company.
21.	van Buggenhout, Sandra, et al. (författare) Structural design of natural plant based foods to promote nutritional quality 2012 Ingår i: Trends in Food Science and Technology. - : Elsevier BV. - 0924-2244 .- 1879-3053. ; 24:1, s. 47-59 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract During traditional industrial processing of fruit and vegetable derived foods, consideration of the eventual retention, bio-accessibility or bio-availability of nutrients has hitherto been a secondary priority. Indeed standard processing of soups and sauces involves treating all ingredients in a similar way, usually by prolonged heat treatment and results in both lowered nutritional value and sensory quality of food products. Such products are typically structured using various additives including starches, gums and stabilizers, which consumers regard as unnatural, rather than exploiting the endogenous structuring potential of the fruit and vegetable ingredients as available at the farm gate. Recent studies undertaken within the EU sponsored 'Healthy Structuring' project have shown how to design an industrially manufactured product with good sensory qualities that is natural and nutritious. The strategy has been to use the inherent structural and nutritional properties of the raw material ingredients, on the one hand to ensure the textural quality of the final product without the use of artificial gums or stabilizers and, on the other hand to optimize the nutritional quality of the final product. This review briefly summarizes both the approach taken and the results obtained within the project.
22.	Shwan, Soran, 1984, et al. (författare) Inside front cover 2014 Ingår i: Catalysis Science and Technology. - 2044-4753 .- 2044-4761. ; 4:9, s. 2688-2688 Tidskriftsartikel (refereegranskat)
23.	Ström, Henrik, 1981 (författare) Numerical simulations of reacting nano-scale flows 2013 Rapport (övrigt vetenskapligt/konstnärligt)abstract The outcome of the CheSC pilot project "Numerical simulations of reacting nano-scale flows" is reported. A Direct Simulation Monte Carlo (DSMC) code has been developed that is able to treat molecular motion in wall-bounded systems with a prescribed pressure difference between an inlet and an outlet. Both homogeneous and heterogeneous chemical reactions can be handled by the code. A number of validation cases are presented to support these claims.An algorithm has been devised and implemented that allows optimization of the distribution of a catalytically active material within a 3D pore where the flow field is described by the present code. The objective function is the outlet concentration of computational molecules that have interacted with the catalytically active surface, and the optimization method used is simulated annealing. The application of a stochastic optimization heuristic is shown to be more efficient within the present DSMC framework than using a macroscopic overlay method. Furthermore, it is shown that the performance of the developed method is superior to that of a gradient search method for the current class of problems.The code produced in the current project represents a suitable starting-point for addressing a number of related research questions, such as reacting multiphase flows on the nano-scale and reacting heterogeneous flows with surface diffusion. The report also contains a discussion on how the present code can be extended to allow for a detailed investigation of these issues.
24.	Thunman, Henrik, 1970, et al. (författare) Advanced Gas Cleaning using Chemical-Looping Reforming (CLR) 2014 Ingår i: 1st International Conference on Renewable Energy Gas Technology, Malmö 2014. Konferensbidrag (refereegranskat)abstract When using a fluidized bed gasification technology to gasify biomass for the downstream synthesis to biofuels or chemicals, the biggest challenge is associated with the reforming of hydrocarbons into desirable gas components. These unwanted hydrocarbons are formed during the primary conversion step of the biomass. They range from ethylene to larger aromatic components or even methane if it is not the desired product, and introduce numerous problems to the operation, but also require additional process steps that significantly influence the competitiveness of the overall process. An efficient way to tackle this problem is to provide catalytic surfaces for hydrocarbon reforming directly inside the gasifier by using a catalytic bed material and/or in one or several secondary reactors. In this work, a concept based on this principle and named Chemical-Looping Reforming (CLR) is presented and it is discussed how this concept has the potential to be implemented for both primary and secondary reforming of hydrocarbons.
25.	Vasiliev, Petr Olegovich, et al. (författare) Strong Hierarchically Porous Monoliths byPulsed Current Processing of Zeolite PowderAssemblies 2010 Ingår i: American Chemical Society. - 1155 Sixteenth Street N.W., Washington, DC 20036 : American Chemical Society. - 1944-8244 .- 1944-8252. ; 2:3, s. 732-737 Tidskriftsartikel (refereegranskat)abstract Binderless hierarchically porous monoliths have been produced from silicalite-1 and ZSM-5 zeolite powders by a rapidand facile powder processing method where the zeolite powders are assembled in a graphite die and subjected simultaneously to acompressive pressure and a pulsed current. Pulsed current processing (PCP) or, as it is commonly called, spark plasma sintering,enables rapid thermal processing of zeolite powder assemblies with heating and cooling rates at 100 °C/minute or more, which resultsin the formation of strong powder bodies without any addition of secondary binders. Nitrogen adsorption measurements show thatit is possible to form strong zeolite monoliths by PCP that maintain between 85 and 95% of the surface area of the as-received silicalite-1and ZSM-5 powders. Line-broadening analysis of X-ray powder diffraction data by the Rietveld method and high-resolution electronmicroscopy showed that the formation of strong interparticle bonds is associated with a local amorphization reaction at the interfacialcontact points between the zeolite particles. The PCP-treated binderless ZSM-5 monoliths display a high selectivity in xylene isomerseparation.
26.	Nilsson, Robert, et al. (författare) Techno-economics of carbon preserving butanol production using a combined fermentative and catalytic approach 2014 Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 161, s. 263-269 Tidskriftsartikel (refereegranskat)abstract This paper presents a novel process for n-butanol production which combines a fermentation consuming carbon dioxide (succinic acid fermentation) with subsequent catalytic reduction steps to add hydrogen to form butanol. Process simulations in Aspen Plus have been the basis for the techno-economic analyses performed. The overall economy for the novel process cannot be justified, as production of succinic acid by fermentation is too costly. Though, succinic acid price is expected to drop drastically in a near future. By fully integrating the succinic acid fermentation with the catalytic conversion the need for costly recovery operations could be reduced. The hybrid process would need 22% less raw material than the butanol fermentation at a succinic acid fermentation yield of 0.7 g/g substrate. Additionally, a carbon dioxide fixation of up to 13 ktonnes could be achieved at a plant with an annual butanol production of 10 ktonnes
27.	Adanez-Rubio, Inaki, et al. (författare) Investigation of Combined Supports for Cu-based Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU) 2013 Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:7, s. 3918-3927 Tidskriftsartikel (refereegranskat)abstract The chemical-looping with oxygen uncoupling (CLOU) process is a novel solution for efficient combustion with inherent separation of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor. In the fuel reactor, the metal oxide releases gas phase oxygen which oxidizes the fuel through normal combustion. In this study, Cu-based oxygen carrier materials that combine different supports of MgAl2O4, TiO2 and SiO2 are prepared and characterized with the objective of obtaining highly reactive and attrition resistant particles. The oxygen carrier particles were produced by spray-drying and were calcined at different temperatures ranging from 950 to 1030oC for 4 h. The chemical-looping performance of the oxygen carriers was examined in a batch fluidized-bed reactor in the temperature range of 900-950oC under alternating reducing and oxidizing conditions. The mechanical stability of the oxygen carriers was tested in a jet-cup attrition rig. All of the oxygen carriers showed oxygen uncoupling behaviour with oxygen concentrations close to equilibrium. During reactivity tests with methane, oxygen carriers with lower mechanical stability showed higher reactivity, yielding almost complete fuel conversion. Oxygen carrier materials based on support mixtures of MgAl2O4/TiO2, MgAl2O4/SiO2 and TiO2/SiO2 showed a combination of high mechanical stability, low attrition rates, good reactivity with methane and oxygen uncoupling behaviour.
28.	Brandin, Jan, 1958- (författare) Usage of Biofuels in Sweden 2013 Ingår i: CSR-2 Catalyst for renewable sources. - Novosibrisk, Russia : Boreskov Institute of Catalysis. - 9785990255777 ; , s. 5-7 Konferensbidrag (refereegranskat)abstract In Sweden, biofuels have come into substantial use, in an extent that are claimed to be bigger than use of fossil oil. One driving force for this have been the CO2-tax that was introduced in 1991 (1). According to SVEBIO:s calculations (2) based on the Swedish Energy Agency´s prognosis, the total energy consumption in Sweden 2012 was 404 TWh. If the figure is broken down on the different energy sources (figure 1) one can see that the consumption roughly distribute in three different, equally sized, blocks, Biofuels, fossil fuels and water & nuclear power. The major use of the fossil fuels is for transport and the water & nuclear power is used as electric power. The main use of the biofuels is for heating in the industrial sector and as district heating. In 2009 the consumption from those two segments was 85 TWh, and 10 TWh of bio power was co-produced giving an average biomass to electricity efficiency of 12%. This indicates a substantial conversion potential from hot water production to combined heat and power (CHP) production. in Sweden 2013 broken down on the different energy sources. In 2006 the pulp, paper and sawmill industry accounted for 95% of the bio energy consumption in the industrial sector, and the major biofuel consumed was black liquor (5). However, the pulp and paper industries also produced the black liquor in their own processes. The major energy source (58%) for district heating during 2006 was woody biomass (chips, pellets etc.) followed by waste (24%), peat (6%) and others (12%) (5). The use of peat has probably decreased since 2006 since peat is no longer regarded as a renewable energy source. While the use of biofuel for heating purpose is well developed and the bio-power is expected to grow, the use in the transport sector is small, 9 TWh or 7% in 2011. The main consumption there is due to the mandatory addition (5%) of ethanol to gasoline and FAME to diesel (6). The Swedish authorities have announced plans to increase the renewable content to 7.5 % in 2015 on the way to fulfill the EU’s goal of 10 % renewable transportation fuels in 2020. However the new proposed fuel directive in EU says that a maximum of 5% renewable fuel may be produced from food sources like sugars and vegetable oils. Another bothersome fact is that, in principle, all rape seed oil produced in Sweden is consumed (95-97%) in the food sector, and consequently all FAME used (in principle) in Sweden is imported as FAME, rape seed oil or seed (6). In Sweden a new source of biodiesel have emerged, tall oil diesel. Tall oil is extracted from black liquor and refined into a diesel fraction (not FAME) and can be mixed into fossil diesel, i.e. Preem Evolution diesel. The SUNPINE plant in Piteå have a capacity of 100 000 metric tons of tall oil diesel per annum, while the total potential in all of Sweden is claimed to be 200 000 tons (7). 100 000 tons of tall oil corresponds to 1% of the total diesel consumption in Sweden. in Sweden for 2010 and a prognosis for 2014. (6). Accordingly, the profoundest task is to decrease the fossil fuel dependency in the transport sector, and clearly, the first generation biofuels can´t do this on its own. Biogas is a fuel gas with high methane content that can be used in a similar way to natural gas; for instance for cooking, heating and as transportation fuel. Today biogas is produced by fermentation of waste (municipal waste, sludge, manure), but can be produced by gasification of biomass, for instance from forest residues such as branches and rots (GROT in Swedish). To get high efficiency in the production, the lower hydrocarbons, mainly methane, in the producer gas, should not be converted into synthesis gas. Instead a synthesis gas with high methane content is sought. This limits the drainage of chemically bonded energy, due to the exothermic reaction in the synthesis step (so called methanisation). In 2011 0.7 TWh of biogas was produced in Sweden by fermentation of waste (6) and there were no production by gasification, at least not of economic importance. The potential seems to be large, though. In 2008 the total potential for biogas production, in Sweden, from waste by fermentation and gasification was estimated to 70 TWh (10 TWh fermentation and 60 TWh gasification) (8). This figure includes only different types of waste and no dedicated agricultural crops or dedicated forest harvest. Activities in the biogas sector, by gasification, in Sweden are the Göteborgs energi´s Gobigas project in Gothenburg and Eon´s Bio2G-project, now pending, in south of Sweden. If the producer gas is cleaned and upgraded into synthesis gas also other fuels could be produced. In Sweden methanol and DME productions are planned for in the Värmlands metanol-project and at Chemrecs DME production plant in Piteå.
29.	Heyne, Stefan, 1979, et al. (författare) Bio-SNG Production via Gasification - Process Integration Aspects for Improving Process Performance 2013 Ingår i: Proceedings of the 21st European Biomass Conference and Exhbition. - 2282-5819. - 9788889407530 ; , s. 1291 - 1304 Konferensbidrag (refereegranskat)abstract This paper presents results from a comprehensive process integration study of different process alternatives for Bio-SNG production based on biomass gasification. The influence of the different conversion steps in the process chain – drying, gasification, gas cleaning, methanation, and gas upgrade – on the overall process performance is investigated. Process bottlenecks as well as heat and material integration aspects are highlighted. Using future energy market scenarios, the energetic, economic, and carbon footprint performance of different process configurations are evaluated from a system perspective. About 63 MLHV of Bio-SNG can be produced from a process converting 100 MWth,LHV (20 wt-% moisture) of forestry residues. Drying of the feedstock from a natural moisture content of 50 wt-% using internal process heat recovery is shown to be important for increasing the process energy efficiency, while the choice of gasification and methanation technology is shown to be of minor importance from a process integration perspective. Amine-based CO2 separation for gas upgrade is shown to be preferable to membrane or pressure-swing adsorption based options both from an economic and Bio-SNG yield perspective. Production cost estimates in the range of 103–112 €2010/MWhSNG indicate that price parity with fossil natural gas would require specific and significant support policies.
30.	Heyne, Stefan, 1979 (författare) Process Integration Opportunities for Synthetic Natural Gas (SNG) Production by Thermal Gasification of Biomass 2010 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Synthetic natural gas (SNG) from gasified biomass is one promising option to produce renewable transport fuels. This thesis presents a process integration study investigating thermal gasification of biomass for the production of SNG and identifies critical conversion steps for the overall process performance. A base case process consisting of an indirect gasification unit followed by tar reforming, aminebased CO2 separation, isothermal methanation and, finally, compression, H2-purification by membrane separation and gas drying is presented. Based on the lower heating value (LHV) of the wet fuel feedstock, the estimated conversion efficiency from biomass to SNG is 69.4 %. The process mass and energy balances are obtained by using flow-sheeting software and are analysed by using pinchmethodology.The integration studies performed highlight the significant potential for improvement of the overall process performance offered by integrated feedstock drying. In particular, steam drying and low-temperature air drying – using available process excess heat – are shown to influence the process performance favourably.The integration of SNG production with existing combined heat and power (CHP) steam power plants is proven to be a promising option to efficiently convert excess heat of the SNG process to electricity. The process integration study performed shows that an increased level of thermal integration leads to an increase in electricity production attributed to the SNG process (100 MWLHV dry fuel input)from 2 to 4.9 MW when using steam drying for feedstock drying, and from 0.5 to 5.6 MW for air drying, without any negative effects on SNG yield.Alternative integration opportunities for biomass gasification not aiming at SNG production specifically, but at replacing fossil fuels for power production, are alsohighlighted. Biomass gasification integrated to a fossil natural gas combined cycle plant results in high biomass-specific electrical efficiencies of up to 49.6 %.
31.	Lindgren, Mikaela, 1987, et al. (författare) Impact of Additives on Zirconium Oxidation by Water: Mechanistic insights from first principles 2013 Ingår i: RSC Advances. - 2046-2069. ; 3:44, s. 21613-21619 Tidskriftsartikel (refereegranskat)abstract Zirconium alloys are widely used as cladding materials employed to contain the fission fuel in nuclear power plants. A limiting factor for fuel longevity is the corrosion property of the zirconium alloys. In the reactor, the main corrodent is water. The oxide forms thermodynamically during hydrogen evolution. Due to the corrosion mechanism, a fraction of the hydrogen is transferred to the alloy. It has long been known that the alloying elements actually control the hydrogen pick-up fraction, HPUF. A mechanism that explains these observations by means of density functional theory calculations is presented and validated. A hydroxylated grain boundary model decorated by various transition metal, TM, ions is employed to study the dependence of the hydrogen evolution reaction, HER, on the choice of TM ion and spin state along the hydride-proton recombination pathway. The efficiency of the system to utilize the overpotential for hydrogen evolution, originating from the overall corrosivity of the alloy, is found to be decisive for the HPUF. A dual origin of the detrimental effects of Co and Ni additives on the HPUF is identified.
32.	Ström, Henrik, 1981, et al. (författare) A multiphase DNS approach for handling solid particles motion with heat transfer 2013 Ingår i: International Journal of Multiphase Flow. - : Elsevier BV. - 0301-9322. ; 53, s. 75-87 Tidskriftsartikel (refereegranskat)abstract In the current work we propose a multiphase DNS method capable of resolving the motion of solid particles coupled with heat transfer effects. The method is based on solving a shared set of momentum and energy balance equations for the carrier phase and the particulate phase. Individualparticles are tracked using a number of volume fraction advection equations. The proposed method is in very good agreement with the available data in the literature for the following cases: isothermal particle motion (in the presence of walls and other particles), natural convection around a stationary particle and solid particles motion accompanied with heat transfer effects. In addition, we show that the method is inherently capable of handling deformable particles (i.e. droplets and bubbles) coexistingwith solid particles. The method is thus well suited to deal with challenging multiphase systems, such as diesel spray combustion with soot formation, spray drying with particle nucleation, biological treatment of waste water etc.
33.	Razmkhah Abharchaei, Parisa, 1985, et al. (författare) Effect of liquid surface residence time distribution on absorption data in a stirred cell 2012 Ingår i: International Symposium on Chemical Reaction Engineering (ISCRE 22), Maastricht, The Netherlands. Konferensbidrag (övrigt vetenskapligt/konstnärligt)
34.	Ström, Henrik, 1981, et al. (författare) Numerical simulations of the interaction between a settling particle and a rising microbubble 2012 Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 1479:1, s. 113-116 Konferensbidrag (refereegranskat)abstract In the current work the hydrodynamic interaction between a settling particle and a rising microbubble is investigated using numerical simulations. The simulations are performed in a multiphase direct numerical simulation (DNS) framework, indicating that all relevant spatial and temporal scales are resolved. It is shown that the method predicts that particle-bubble attachment is possible when the initial horizontal distance between their centers is small and that the particle will pass the bubble without attaching when this initial distance is large. Furthermore, it is shown that the probability of a successful attachment is lower if the bubble Eötvös and Morton numbers are significantly larger than unity.
35.	Carabante, Ivan, et al. (författare) Influence of Zn(II) on the adsorption of arsenate onto ferrihydrite 2012 Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:24, s. 13152-13159 Tidskriftsartikel (refereegranskat)abstract Addition of iron oxide to arsenic-contaminated soil has been proposed as a means of reducing the mobility of arsenic in the soil. Arsenic and zinc are common coexisting contaminants in soils. The presence of zinc therefore may affect the adsorption properties of arsenic on iron oxide, and may thus affect its mobility in the soil. The influence of Zn(II) on the adsorption of arsenate ions on iron oxide was studied. Batch adsorption experiments indicated that Zn(II) increased the arsenate removal from a solution by ferrihydrite at pH 8. However, ATR-FTIR spectroscopy showed that no adsorption of arsenate on a ferrihydrite film occurred at pD 8 in the presence of Zn(II). Precipitation of zinc hydroxide carbonate followed by arsenate adorption onto the precipitate was found to be a plausible mechanism explaining the arsenate removal from a solution in the presence of Zn(II) at pH/pD 8. The previously suggested mechanisms attributing the enhanced removal of arsenate from solution in the presence of Zn(II) to additional adsorption on iron oxides could not be verified under the experimental conditions studied. It was also shown that at pH/pD 4, the presence of Zn(II) in the system did not significantly affect the adsorption of arsenate on ferrihydrite.
36.	Carabante, Ivan, et al. (författare) Reutilization of porous sintered hematite bodies as effective adsorbents for arsenic(V) removal from water 2014 Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:32, s. 12689-12696 Tidskriftsartikel (refereegranskat)abstract A method was developed to enhance the arsenic adsorption capacity of porous bodies of sintered hematite. The method comprised the formation of a coating of 1 wt % iron oxide nanoparticles on the raw material. The nanoparticles showed two distinct habits: spherical habit, likely ferrihydrite, and acicular habit, likely goethite and/or akaganéite. The specific surface area of the hematite raw material increased from 0.5 to 3.75 m2/g, and the adsorption capacity increased from negligible to 0.65 mg of [As]/g as calculated from equilibrium and breakthrough adsorption data. Equilibrium adsorption data of arsenate on the adsorbent from a solution at pH 5 followed the Langmuir model, while breakthrough adsorption data for a 500 μg/L arsenate solution at pH 5 followed the Thomas model. The adsorbed arsenic could be desorbed using distilled water at pH 12. These results show the potential for the reutilization of waste products comprising coarse hematite bodies as adsorbents.
37.	Engström, Andreas, et al. (författare) Synthesis of a TiCN – SiC polyhedron and elongated crystals nanopowder at low nitrogen concentration 2012 Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 81, s. 148-150 Tidskriftsartikel (refereegranskat)abstract At room temperature diluted TiCl4 and CCl4 were reduced by sodium particles and mixed with a polycarbomethylsilane (PCS) solution to yield a precursor. It was dried and subsequently annealed at 1300 °C, 1400 °C and 1450 °C in a tube furnace using argon with 10 ppm N2. After the 1450 °C annealing a nanocrystalline powder of TiC0.5 N0.5–SiC polyhedron and elongated crystals was obtained. At the low nitrogen concentration during annealing a gradual nitration is proposed. It is promoted by carbon gaseous species, precursor oxidation, a sufficient temperature and a summarised nitrogen surplus compared to the titanium and carbon amount.
38.	Seddighi, Sadegh, 1977 (författare) Combustion, Fluid Dynamics and Heat Transfer in Oxy-fuel and Air-Fired CFB boilers 2014 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract The studies described in this thesis develop and encode modeling tools for the design and scale-up of oxy-fuel circulating fluidized bed (CFB) boilers across a wide range of operational conditions. The modeling comprises fluid dynamics, combustion, and heat transfer and uses expressions that are proposed in this work or derived from the literature, together with experimental data obtained under both oxy-fuel-fired and air-fired conditions. First, a mathematical model that takes into account both the mixing and combustion kinetics of both heterogeneous and homogeneous reactions is developed for simulating gas and solids combustion under air- and oxy-fuel-fired conditions. Second, a new correlation for gas mixing is proposed based on the multi-phase structure of the gas-solid flow in the furnace. Third, a mathematical model of CFB heat transfer is developed that accounts separately for convective and radiative heat transfer under air-fired and oxy-fuel-fired conditions. Model simulations and validations are carried out for a broad range of operational conditions, involving both oxy-fuel firing and air-firing. The results are in good agreement with the data obtained using laboratory-scale (100-kW) and 4-MW industrial-scale, oxy-fuel-fired units. The model is used subsequently to investigate the design of a utility-scale (300–1100 MW) oxy-fuel-fired CFB boiler.In the laboratory-scale unit, to describe the axial mixing, the furnace is divided into three distinct zones in which both mixing and kinetics control the combustion. However, the rate of mixing is shown to be lower in the dense bed and the upper parts of the furnace, whereas it is higher in the zone above the dense bed due to bubble eruptions and secondary gas injections.For the 4-MW oxy-fuel-fired unit, the modeling and experimental results show that both the peak CO concentration and lateral gas maldistribution increase with increasing O2 concentration at the inlet. The modeling results show that the specific emission of CO [g/MJ] at the furnace outlet decreases with increases in the inlet concentration of O2. The outcomes of modeling heat transfer show good agreement with the experimental results with respect to the levels of heat extraction and temperature in the furnace and the heat extraction required from the external heat exchanger (EHE). The utility-scale simulations reveal that the furnace temperature increases at elevated inlet O2 concentrations. To limit the in-furnace temperature to an acceptable level (i.e., 1273 K to avoid ash melting), the modeling indicates that the external circulating solids flow has to be increased substantially; flow rates of 10, 19, and 31 kg/m2s are required to ensure inlet O2 concentrations of 48%, 56%, and 70%, respectively.
39.	Brandin, Jan, 1958-, et al. (författare) High-temperature and high concentration SCR of NO with NH3 : application in a CCS process for removal of carbon dioxide 2012 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 191, s. 218-227 Tidskriftsartikel (refereegranskat)abstract This study investigates several commercial selective catalytic reduction (SCR) catalysts (A–E) for application in a high-temperature (approximately 525 °C) and high-concentration (5000 ppm NO) system in combination with CO2 capture. The suggested process for removing high concentrations of NOx seems plausible and autothermal operation is possible for very high NO concentrations. A key property of the catalyst in this system is its thermal stability. This was tested and modelled with the general power law model using second-order decay of the BET surface area with time. Most of the materials did not have very high thermal stability. The zeolite-based materials could likely be used, but they too need improved stability. The SCR activity and the possible formation of the by-product N2O were determined by measurement in a fixed-bed reactor at 300–525 °C. All materials displayed sufficiently high activity for a designed 96% conversion in the twin-bed SCR reactor system proposed. The amount of catalyst needed varied considerably and was much higher for the zeolithic materials. The formation of N2O increased with temperature for almost all materials except the zeolithic ones. The selectivity to N2 production at 525 °C was 98.6% for the best material and 95.7% for the worst with 1000 ppm NOx in the inlet; at 5000 ppm NOx, the values were much better, i.e., 98.3 and 99.9%, respectively.
40.	Faisal, Abrar, et al. (författare) MFI zeolite as adsorbent for selective recovery of hydrocarbons from ABE fermentation broths 2014 Ingår i: Adsorption. - : Springer Science and Business Media LLC. - 0929-5607 .- 1572-8757. ; 20:2-3, s. 465-470 Tidskriftsartikel (refereegranskat)abstract 1-Butanol and butyric acid are two interesting compounds that may be produced by acetone, butanol, and ethanol fermentation using e.g. Clostridium acetobutylicum. The main drawback, restricting the commercialization potential of this process, is the toxicity of butanol for the cell culture resulting in low concentrations of this compound in the broth. To make this process economically viable, an efficient recovery process has to be developed. In this work, a hydrophobic MFI type zeolite with high silica to alumina ratio was evaluated as adsorbent for the recovery of butanol and butyric acid from model solutions. Dual component adsorption experiments revealed that both butanol and butyric acid showed a high affinity for the hydrophobic MFI zeolite when adsorbed from aqueous model solutions. Multicomponent adsorption experiments using model solutions, mimicking real fermentation broths, revealed that the adsorbent was very selective to the target compounds. Further, the adsorption of butyric and acetic acid was found to be pH dependent with high adsorption below, and low adsorption above, the respective pKa values of the acids. Thermal desorption of butanol from MFI type zeolite was also studied and a suitable desorption temperature was identified.
41.	Heyne, Stefan, 1979, et al. (författare) Impact of choice of CO2 separation technology on thermo-economic performance of Bio-SNG production processes 2014 Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 38:3, s. 299-318 Tidskriftsartikel (refereegranskat)abstract Three different CO2 separation technologies for production of synthetic natural gas (SNG) from biomass gasification – amine-based absorption, membrane-based separation and pressure swing adsorption – are investigated for their thermo-economic performance against the background of different possible future energy market scenarios. The studied scale of the SNG plant is a thermal input of 100 MWth,LHV to the gasifier at a moisture content of 20 wt-% with a preceding drying step reducing the biomass' natural moisture content of 50 wt-%. Preparation of the CO2-rich stream for carbon capture and storage is investigated for the amine-based absorption and the membrane-based separation technology alternatives. The resulting cold gas efficiency ηcg for the investigated process alternatives ranges between 0.65 and 0.695. The overall system efficiency ηsys ranges from 0.744 to 0.793, depending on both the separation technology and the background energy system. Amine-based absorption gives the highest cold gas efficiency whereas the potential for cogeneration of electricity from the process' excess heat is higher for membrane-based separation and pressure swing adsorption. The estimated specific production costs for SNG cSNG for a process input of 90.3 MWth,LHV at 50 wt-% moisture vary between 103–127 €2010/MWhSNG. The corresponding production subsidy level csubsidy needed to achieve end-user purchase price-parity with fossil natural gas is in the range of 56–78 €2010/MWhSNG depending on both the energy market scenario and the CO2 separation technology. Sensitivity analysis on the influence of changes in the total capital cost for the SNG plant on the production cost indicates a decrease of about 12% assuming a 30% reduction in total capital investment. Capture and storage of biogenic CO2 – if included in the emission trading system – only becomes an option at higher CO2 charges. This is due to increased investment costs but, in particular, due to the rather high costs for CO2 transport and storage that have been assumed in this study.
42.	Isaksson, Johan, 1983, et al. (författare) Integration of biomass gasification with a Scandinavian mechanical pulp and paper mill 2011 Ingår i: Proceedings of the 24th International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental impact of Energy Systems, ECOS 2011, Novi Sad, Serbia, July 4-7, 2011. ; , s. 3668-3679 Konferensbidrag (refereegranskat)abstract The Scandinavian mechanical pulp and paper industry has been facing great challenges during the past decades, mainly because of a declining demand for newsprint, and higher prices on raw material and energy. One way of increasing profitability is to produce more value-addedproducts besides the production of pulp and paper, thus creating a “biorefinery”. Gasification of residues from forestry, falling bark and cutter shavings has been raised as a promising option for utilizing low-value biomass to produce syngas, which can be further synthesized to, forexample, transportation fuels or chemicals. In this paper, the results of a case study on biomass gasification integrated with a Swedish thermo-mechanical pulp and paper mill (TMP mill) are presented. The mill has an annual paperproduction of 760 000 tonnes and is co-located with a large saw mill. The demand for raw material to the saw mill is about twice as large as the product output, on a volume basis, which potentially leaves a substantial raw material base for a gasifier. A simplified pinch analysis usingthe HLMPP (Heat Load Model for Pulp and Paper) tool has earlier been performed for the studied TMP mill. This paper evaluates the integration of biomass gasification, includingproduction of electricity or liquid transportation fuels, with the studied TMP mill. It also presents the impact of such integration on the overall heat and mass balances. Proper pre-treatment of the biomass prior to gasification as well as treatment of the product gas have also beenevaluated with respect to heat integration aspects. The results of this initial study indicate an interesting match between the constituting parts, i.e. the pulp and paper mill, the saw mill and the production of electricity and transportation fuels. This work will therefore be followed by an economic evaluation based on a more technically detailed study.
43.	Kantarelis, Efthymios, 1982- (författare) Catalytic Steam Pyrolysis of Biomass for Production of Liquid Feedstock 2014 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract The current societal needs for fuels and chemical commodities strongly depend on fossil resources. This dependence can lead to economic instabilities, political problems and insecurity of supplies. Moreover, global warming, which is associated with the massive use of fossil resources, is a dramatic “collateral damage” that endangers the future of the planet.Biomass is the main renewable source available today that can, produce various liquid, gaseous and solid products. Due to their lignocellulosic origin are considered CO2 neutral and thus can generate CO2 credits. Biomass processing can meet to the challenge of reducing of fossil resources by producing a liquid feedstock that can lessen the “fossil dependence” and /or meet the increased demand via a rapidly emerging thermochemical technology: pyrolysis.The ultimate goal of this process is to produce liquid with improved properties that could directly be used as liquid fuel, fuel additive and/or feedstock in modern oil refineries and petrochemical complexes.However, the liquids derived from biomass thermal processing are problematic with respect to their handling and end use applications. Thus, alternative routes of advanced liquid feedstock production are needed. Heterogeneous catalysis has long served the oil refining and petrochemical industries to produce a wide range of fuels and products. The combination of biomass pyrolysis and heterogeneous catalysis (by bringing in contact the produced vapours/liquids with suitable catalysts) is a very promising route.In this dissertation, the exploitation of biomass to produce of liquid feedstock via pyrolysis over a multifunctional catalyst and in a steam atmosphere is investigated. Steam pyrolysis in a fixed bed reactor demonstrated that steam can be considered a reactive agent even at lower temperatures affecting the yields and the composition of all the products. The devolatilisation accelerates and the amount of final volatile matter in the char.Fast pyrolysis in the presence of steam results in improved and controlled thermal decomposition of the biomass; higher liquid yields and slightly deoxygenated liquid products are also obtained.Steam pyrolysis over a bi-metallic Ni-V catalyst can produce liquids of improved quality (lower O content) and also provide routes for selective deoxygenation. However, a decrease in liquid yield was observed.The combination of metal and acid catalysts (Ni-V/HZSM5) shows enhanced deoxygenation activity and increased H preservation in the produced liquid. The final O content in the liquid was 12.83wt% at a zeolite (HZSM5) loading of~75wt%; however, the yield of the obtained liquid was substantially decreased. Moreover, increased coke formation on the catalyst was observed at highest zeolite rate.The increased catalyst space time (τ) results in a lower liquid yield with reduced oxygen (7.79 wt% at τ =2h) and increased aromatic content. The coke deposited per unit mass of catalyst is lower for longer catalyst space times, while the char yield seems to be unaffected.The evaluation of the stability of the hybrid catalyst showed no significant structural defects and activity loss when the catalyst was regenerated at a low temperature (550οC).
44.	König, C.F.J., et al. (författare) Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy 2014 Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 113, s. 1895-1901 Tidskriftsartikel (refereegranskat)abstract Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature "chemical looping desulfurization" process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO2. Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a "chemical looping desulfurization" reactor. The "fuel reactor" gas contained H2, CO, CH4 and H2S, similar as in the producer gas, and the "oxidizing reactor" contained diluted O2. Mass spectrometry showed that most of the H2S is taken up by the sample in the "fuel reactor" part, while also some unwanted SO2 is generated in the "fuel reactor" part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn3O4 is transformed in the presence of H2S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn3O4 oxidizes some H2S to the undesired SO2 in the fuel reactor. Upon exposure to O2, MnS is again oxidized to Mn3O4 via MnO, releasing SO2. The presence of CO and/or CH4 in the fuel reactor has no effect on this mechanism. Measuring the structure-performance relationship of gas cleaning materials with in situ methods will enable knowledge-based materials development for improved performance. © 2013 Elsevier Ltd. All rights reserved.
45.	Näzelius, Ida-Linn, et al. (författare) Influence of peat addition to woody biomass pellets on slagging characteristics during combustion 2013 Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:7, s. 3997-4006 Tidskriftsartikel (refereegranskat)abstract Upgraded biofuels such as pellets, briquettes, and powder are today commonly used in small as well as large scale appliances. In order to cover an increasing fuel demand new materials such as bark, whole tree assortments, and peat are introduced. These materials have higher ash content which is why they are potentially more problematic compared with stem wood. In general, few studies can be found regarding cocombustion of peat and biomass and in particular where the slagging tendencies are discussed. The overall objective of this study was therefore to determine the influence of peat addition to woody biomass pellets on slagging characteristics. Two different peat assortments (peat A and B) were copelletized separately in four different dry matter levels (0-5-15-30 wt %) into stem wood and energy wood, respectively. Peat A was a traditional Scandinavian fuel peat, with a high ash and Si content (carex), and peat B had a low ash content and relatively high Ca/Si ratio (sphagnum) chosen for its special characteristics. The produced pellets were combusted in a commercial underfed pellet burner (15 kW) installed in a reference boiler. The collected deposits (bottom ash and slag) from the combustion experiments were chemically characterized by scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) and X-ray diffraction (XRD) regarding the elemental distribution and morphology and phase composition, respectively. In addition, the bottom ashes were characterized according to inductively coupled plasma atomic emission spectroscopy (ICP-AES). To interpret the experimental findings chemical equilibrium model calculations were performed. The slagging tendency increased when adding peat into the woody biomasses. Especially sawdust with its relatively low ash and Ca content was generally more sensitive for the different peat assortments. Cofiring with the relatively Si and ash rich peat A resulted in the most severe slagging tendency. A significant increment of the Si, Al, and Fe content and a significant decrement of the Ca content in the slag could be seen when increasing the content of peat A in both woody biomasses. The slagging tendency increased when adding peat A because high temperature melting Ca-Mg oxides react to form more low temperature melting Ca/Mg-Al-K silicates. The slagging tendency was significantly lower when adding the more ash poor peat B, with relatively high Ca/Si ratio, into the woody biomass fuels compared with the peat A mixtures. The slag from the peat B mixings had a slightly higher Ca content compared with the Si content and a clearly higher content of Ca compared with the peat A mixtures. There were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting K-silicate rich melt was formed when peat B was added to the woody biomasses.
46.	Rydén, Magnus, 1975, et al. (författare) Measuring attrition resistance of oxygen carrier particles for chemical looping combustion with a customized jet cup 2014 Ingår i: Powder Technology. - : Elsevier BV. - 1873-328X .- 0032-5910. ; 256, s. 75-86 Tidskriftsartikel (refereegranskat)abstract A customized jet cup for measuring attrition resistance of oxygen carrier particles for chemical looping combustion has been constructed and used to evaluate 25 different material samples, all of which previously have been subject to continuous operation in chemical looping reactors at Chalmers University of Technology. The effect of continuous operation has been assessed by comparing attrition behavior of fresh particles with that of used ones. It is concluded that the correlation between the jet cup tests and operational experience is robust, and that there is always considerable difference in attrition resistance between fresh and used particles of the same batch. Composite materials with NiO or Fe2O3 as active phase and Al2O3-, NiAl2O4- or MgAl2O4-based support and materials based on the CaMnO3-δ perovskite structure typically had high attrition resistance, which improved further following operation with fuel. Combined (FexMn1-x)2O3 oxides and all materials containing smaller or larger amounts of either CuO or ZrO2 experienced reduced attrition resistance during operation with fuel, and usually also had low attrition resistance to begin with. Fresh particles of the commonly used oxygen carrier ilmenite had reasonably high attrition resistance, while ilmenite that had been subject to chemical looping combustion of natural gas showed higher rate of attrition. No strong correlation between the commonly used crushing strength index and attrition resistance measured with jet cup could be established, but it was clear that particles with a crushing strength above 2N were much more likely to have high attrition resistance compared to softer particles. As compared to crushing strength, the jet cup testing was better correlated to attrition in actual operation.
47.	Sjöblom, Jonas, 1968, et al. (författare) Capture of Automotive Particulate Matter in Open Substrates 2013 Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:25, s. 8373-8385 Tidskriftsartikel (refereegranskat)abstract Open filters (with low pressure drop) have potential for energy-efficient reduction of particulate matter (PM) from engines. In the work reported here, the capture efficiency of PM in open substrates has been investigated using PM from a real engine under various flow conditions and sampling settings. The observed capture efficiency (CE) confirmed the expected trends that increased residence time and increased temperature give better CE. However, the volatile content (assumed to be hydrocarbons, HC) can increase the apparent CE due to rapid evaporation and/or shrinkage of the PM. In order to quantify these effects, a conceptual model has been implemented that can be used as an in situ analyzer of the PM properties. The results show how exhaust treatment (heating and/or dilution) changes the characteristics of the PM. These properties affect CE and can be used for subsequent catalyst optimization. In addition, the method developed here was used to analyze nucleation-mode PM from a special fuel injection strategy. The results revealed that these particles were mainly nonvolatiles, demonstrating the usefulness of this characterization methodology. Furthermore, an equation for diffusion losses in the rotary dilutor for the DMS500 is presented.
48.	Sjöblom, Jonas, 1968, et al. (författare) Capture of automotive particulate matter in open substrates 2013 Ingår i: Proceedings of the 17th ETH Conference on Combustion Generated Nanoparticles, 2013, Zürich, Switzerland. Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Background: Open filters (with low pressure drop) have potential for energy efficient reduction of particulate matter (PM) from internal combustion engines. For some applications, open substrates may suffice. Furthermore, the use of a flow-through filter (e.g. an oxidation catalyst) upstream a wall-through filter (i.e. diesel particulate filter, DPF) will decrease the pressure drop build-up, since smaller particles will be captured in the upstream open filter and a narrower particle size distribution (PSD) with a shift towards larger sizes will enter the DPF. Furthermore, the PM from internal combustion engines is prone to changes (via changes in gas composition and temperature) and it is therefore extremely challenging to characterize. Experimental: In the work reported here, the capture efficiency of PM in open substrates (bare cordierite and alumina-coated cordierite monoliths) has been investigated using PM from a real engine under various flow conditions (varying residence times and temperatures) and sampling settings (dilution ratios) using a DMS500 from Cambustion. However, the capture efficiency was affected by removal of volatiles (hydrocarbons) influencing both size and numbers. In order to quantify these effects, a conceptual model has been implemented that can be used as an in-situ analyzer of the PM properties. This model includes loss of pure volatile particles and shrinkage of semi-volatile particles. Although physically sound, the model is empirical and the parameters needs fitting to experiments.Results: The observed capture efficiency (CE) confirmed the expected trends that increased residence time and increased temperature gave higher CE. However, the volatile content (assumed to be hydrocarbons, HC) can increase the apparent CE due to rapid evaporation and/or shrinkage of the PM. The results show how exhaust treatment (heating and/or dilution) changes the characteristics of the PM. These properties affect capture efficiency and can be used for subsequent catalyst optimization. In addition, the method developed here was used to analyze nucleation mode PM from a special fuel injection strategy. The results revealed that these particles were mainly non-volatiles, demonstrating the usefulness of this characterization methodology. Furthermore, an equation for diffusion losses in the rotary dilutor for the DMS500 is presented. Figure 1. Left: The particle size distribution and the corresponding volatile contribution using a sigmoidal function describing the size-dependent fractions. Right: The experimental and fitted capture efficiencies.The conceptual model developed here relies upon the assumption that the experimental setup is reliable and that the theory (provided by diffusion equations and/or correlations) hold for inert particles. In order to verify these assumptions a set of experiments was performed using inert NaCl particles generated by an atomizer (Topas ATM230). It could be confirmed that the experimental CE corresponded to the theoretical CE. Thus the experimental setup and methodology was validated. Conclusions: Although the evaporation model offers a plausible explanation to the phenomena observed, conclusive validation still remains. However, assuming that this model is applicable, a number of important conclusions could be drawn1.The monolith channel serves as an effective HC trap and thus increases any HC evaporation. The resulting change in PSD should be taken into account when simulating the catalyst reduction in open filters.2.By analysis of the fitted HC contribution, interferences of the PM characteristics can be made in-situ (in terms of volatile content). This information would be very hard to obtain by other means.3.The use of partial injection strategy could be a useful way to produce small PM that is suitable for kinetic studies and for the bridging between lab-scale soot (e.g. Printex U) and real diesel PM emissions.Reference:This work has recently been published online in Industrial & Engineering Chemical Research, DOI: 10.1021/ie4004333.
49.	Ström, Henrik, 1981, et al. (författare) Heat and mass transfer in automotive catalysts - the influence of turbulent velocity fluctuations 2012 Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 83, s. 128-137 Tidskriftsartikel (refereegranskat)abstract Monolithic reactors employed in automotive exhaust gas aftertreatment typically operate under fluctuating flow conditions. These fluctuations in the volumetric flow rate through the catalyst are caused by engine pulsations and the upstream exhaust gas turbulence.In the current work, the effects of the turbulent-to-laminar transition on the conversion of pollutants under mass-transfer limited operation of a monolithic reactor are investigated using numerical simulations. The most notable effect of the turbulence is an introduction of temporal fluctuations to the observed conversion at the outlet. These fluctuations are attributed to variations in the axial velocity (and thus the retention time) in the channel.A simplistic model for a single monolith channel in a tanks-in-series framework is suggested that captures this effect of the upstream turbulence on the dimensionless heat and mass transfer numbers in automotive catalysts. The model can be used to resolve the transient variations of the heat and mass transfer when the upstream turbulent characteristics are known. The effects of such variations on the catalytic conversion are likely to be most pronounced for reactions with negative-order kinetics when operating close to ignition or extinction.
50.	Ström, Henrik, 1981, et al. (författare) Turbulent operation of diesel oxidation catalysts for improved removal of particulate matter 2012 Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 69:1, s. 231-239 Tidskriftsartikel (refereegranskat)abstract This paper proposes that a diesel oxidation catalyst (DOC) operating within the fully turbulent flow regime is an efficient means of reducing the contents of particulate matter in the exhaust gases. The suggested mode of operation is in contrast to the fact that the DOCs are typically operated within the laminar flow regime. In the paper, the particle trapping efficiency and pollutantconversion in turbulent ceramic DOCs are calculated using both mass-transfer correlations available in literature and computational fluid dynamics (CFD). It is shown that a turbulent DOC substantially increases the removal of small particulates from the exhaust gases. This indicates the potential of the aftertreatment system to comply with the forthcoming number-based emission legislations on particulate matter. In addition, the turbulent DOC can be used to optimize the overall performance of acombined system consisting of a DOC and a diesel particulate filter.

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