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  • 1.
    Carlsson, Gunilla
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Axrup, Lars
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden.
    Ljungqvist, Carl-Henrik
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden..
    Nyflott, Asa
    Stora Enso, Karlstad Res Ctr, SE-65009 Karlstad, Sweden.;Karlstad Univ, SE-65188 Karlstad, Sweden..
    The use of fluorescence microscopy and image analysis to characterize the porous structure in micro fibrillar cellulose gel - Part I: Brownian motion2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 2, p. 190-197Article in journal (Refereed)
    Abstract [en]

    The porous structure of a micro fibrilar cellulose, MFC, gel was studied by fluorescence microscopy and image analysis. The Brownian motion of fluorescent labelled carboxylated latex spheres, probes, was investigated at both high, 0.1-5 wt%, and low, 0-20 ppm, concentrations of MFC. The developed tracking program provides trajectories for probes. The trajectories can be studied according to either the individual approach or the ensemble approach to give complementary information regarding the fibrilar system. The Brownian motion can be used in the range 0 to 1.0 wt% MFC and the percentage of idle probes can be used when the concentrations exceeds 1.0 wt% MFC. The Brownian motion was found to be pH dependent both for the low and the high concentration regimes.

  • 2.
    Dahlin, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Na/S balances at Skoghall mill 2015: Balances after reconstruction of the fiber line2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The scope of this master thesis was to investigate how a reconstruction at Skoghall Mill had changed the Na/S balance as well as evaluating how a new chemical plant manufacturing the mill’s chlorine dioxide would affect the balance. This was done by analyzing ingoing and outgoing process streams at the mill for sodium and sulfur and using obtained flow data for the period after the reconstruction. A balance was made to simulate how the system behaved at the time as well as balances simulating different shares of bleached pulp being manufactured. Balances with three possible types of chemical plants were also made, as well as calculations of the operating cost for each type of plant. From the balances and the operating costs it was concluded that the HPA process was the most beneficial for the Na/S balance as well as having the lowest operating cost.

  • 3.
    Danish, Muhammad
    et al.
    E China Univ Sci & Technol, Peoples R China; Gujarat Univ, Pakistan.
    Naqvi, Muhammad
    Malardalen Univ.
    Farooq, Usman
    Gujarat Univ, Pakistan.
    Naqvi, Salman
    Univ Teknol PETRONAS, Malaysia..
    Characterization of South Asian agricultural residues for potential utilization in future 'energy mix'2015In: Energy Procedia / [ed] J. Yan, T. Shamim, H Li SK Chou, Elsevier, 2015, Vol. 75, p. 2974-2980Conference paper (Refereed)
    Abstract [en]

    This paper characterizes various locally available agricultural residues in South Asian region to evaluate their potential as feedstock for renewable energy production and contributing toward solving energy crisis and environmental issues. The thermo-chemical characterization has been performed in order to determine if the residues have potential to be used in biomass conversion technologies producing combined heat and power. The characterization methods for comparing different agricultural residues include proximate and ultimate analysis, heating value, ash content, thermo gravimetric analysis (TGA) and structural composition analysis (SCA). Widely available agricultural wastes in South Asian region were selected for the characterization i.e. bagasse, almond shell, corn cob, cotton stalks, wheat straw, sawdust, corn leaf, rice husk, rice straw, and corn straw. The analysis showed that the corn cob had the highest moisture content that will result in low energy efficiency of the thermal conversion technology due to energy requirement for drying. Whereas almond shell had the lowest moisture content. Ash and volatile contents were found to be highest in rice straw and almond shell respectively. The thermo gravimetric analysis showed that most of the agricultural residues can be easily decomposed and represent potential feedstock for biomass flexible combined heat and power systems through pyrolysis or gasification.

  • 4.
    Deshpande, Raghu
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    The initial phase of the sodium bisulfite pulping of softwood dissolving pulp2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way.

    Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate.

  • 5.
    Ekbåge, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Process modelling based on data from an evaporation and a CTMP process: Analysis of energy efficiency and process variability2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, paperboard, steam and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. This data may be of time-varying nature and the variability might potentially span from seasonal to time-wise shorter variations and there are in some cases a need for predicting certain properties.

    By applying models based on process data there is a potential to increase the knowledge of the process characteristics, investigate the applicability of predictive models and identify optimization opportunities. Based on data from an evaporation and a CTMP plant, process models have been developed with the aim of improving the energy efficiency and studying process variability.  

  • 6.
    Fredriksson, Robert
    et al.
    AkzoNobel , Separations Products, Bohus, Sweden.
    Samuelsson, Jörgen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Fornstedt, Torgny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    The Importance of Overloading Studies in Method Development: A Case Study2012Conference paper (Refereed)
  • 7. Khan, Z.
    et al.
    Yusup, S.
    Kamble, P.
    Naqvi, Muhammad
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Watson, I.
    Assessment of energy flows and energy efficiencies in integrated catalytic adsorption steam gasification for hydrogen production2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 225, p. 346-355Article in journal (Refereed)
    Abstract [en]

    This study addresses the energy flows and energy efficiency of integrated catalytic adsorption biomass steam gasification for hydrogen production in a pilot scale bubbling fluidized bed system utilizing palm kernel shell as feedstock. The integrated catalytic adsorption utilizes catalyst and CO2 adsorbent together in the single fluidized bed gasifier. Various variables such as effect of temperature (600–750 °C), steam to biomass ratio (1.5–2.5 w/w), adsorbent to biomass ratio (0.5–1.5 w/w), fluidization velocity (0.15–0.26 m/s) and biomass particle size (0.355–0.500 to 1.0–2.0 mm) are investigated. The results imply that the overall requirement of gasification energy increases with increasing gasification temperature, steam to biomass ratio, fluidization velocity, and decreases with adsorbent to biomass ratio whilst no significant increase is observed by varying the biomass particle size. However, a slight reduction in required energy is observed from 600 °C to 675 °C which might be due to strong CO2 adsorption, an exothermic reaction, and contributes to the energy requirements of the process. Besides, hydrogen-based energy efficiencies increase with increasing temperature while first increases to a medium value of steam to biomass ratio (2.0), adsorbent to biomass ratio (1.0) and fluidization velocity (0.21 m/s) followed by a slight decrease (or remains unchanged). The integrated catalytic adsorption steam gasification is found to be a high energy consuming process and thus, waste heat integration needs to be implemented for feasible hydrogen production

  • 8.
    Lefevr, Avlina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Methods of Chemical and Physical Modification Used in Increasing Poor Solubility of Orally Administered Medications: -2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Poor-water solubility of chemical compounds accounts for 40% and more of new medicalentities become discarded. Low solubility results in chemical substances cannot be deliveredto the target organ or cells, for that reasons there is a need to increase low water-solubilitywith various physical and chemical methods. In this paper we have examined various physicaland chemical methods of increasing poor solubility suggested in the pharmacological booksand journals and looked at how these methods can be practically used in increasing poorwater-solubility of four medications from the WHO Essential List of Medications. Thefindings of the paper are that several methods have shown good results for dissolution invivo: complexation with cyclodextrins and use of surfactants (physical methods), developmentprodrug (chemical methods). Improved medications provide a good solution for chronically illpatients who take high doses over a long period of time. Another benefit of improvedsolubility is lower cost of treatment, which is an important issue in poor regions of the world.

  • 9.
    Magnusson, Hans
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. NLK-Celpap Engineering AB.
    Silica and the recovery of pulping chemicals: Technology and economy1992Conference paper (Refereed)
  • 10.
    Olsson, Robert
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Imbibition into model calcium carbonate coatings of fluids with different dipole moments2006In: Appita journal, ISSN 1038-6807, Vol. 59, no 6, p. 471-485Article in journal (Refereed)
1 - 10 of 10
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