Challenging Biomass Feedstocks for Energy and Chemicals

The Nordic countries have a long tradition of utilizing agro-industrial sidestreams for heat and power production and recovery of chemicals. A typical example is black liquor from pulp mills. Here, the woody biomass undergoes a digestion process where the fibers are separated to produce pulp for paper production. The liquid by-product from the digester, black liquor, contains wood lignin and the spent cooking chemicals. Through the chemical recovery cycle, the black liquor is utilized for heat and power production and recovery of cooking chemicals. Worldwide, there are several challenging biomass sidestreams that can be utilized in a similar fashion as with black liquor. Some examples of these are vinasse from the integrated sugar-ethanol production process; straw and manure from agriculture sources; forest residues; by-products from the food industry; etc. This book chapter will review the availability of these types of feedstocks and discuss their applicability and challenges to be used for energy and chemicals. Pyrolysis, gasification, and combustion are the potential thermal conversion options considered for the utilization of these types of challenging biomass feedstocks

A comparative assessment of biomass ash preparation methods using X-ray fluorescence and wet chemical analysis

X-ray fluorescence (XRF) spectroscopy is a rapid method used to determine the composition of biomass ash, but the accuracy of the method is sensitive to various factors including ash preparation methods. In this study different types of biomass ash were examined by using wet chemical analysis (WCA) and compared with the respective XRF results. The biomass ash was initially prepared in accordance with the European Standard method at 550 °C. At this low combustion temperature the amount of residual unburned carbon is significant. To eliminate this, the ashes were heated at higher temperatures: a batch of twenty biomass ashes were heated at 850 °C and a batch of five heated to 815 °C. At these higher temperatures there may be loss of inorganic components by vaporisation. Variation in these effects may lead to unreliable results. The relationship between XRF and WCA results are given by regression equations. The ashes processed at 815 °C show better agreement between the two analysis methods

Observations on the release of gas-phase potassium during the combustion of single particles of biomass

One of the more significant characteristics of solid biomass fuels as compared to coal is the quantity of potassium that they contain. Potassium content influences ash deposition and corrosion mechanisms in furnaces, the effects of which may differ depending on phase transformations of potassium species in the gas phase and condensed phase. The fate of potassium from the fuel during the combustion process is therefore an important concern. To investigate this, an experimental method is presented in which the release patterns from single particles of various biomass fuels are measured by use of flame emission spectroscopy implemented using a custom-built photo-detector device. Single particles of fuel are combusted in a methane flame with a gas temperature of ∼1800 K. The observed potassium release patterns for thirteen solid biomass materials are presented. The data are analyzed to examine the relationships between: the level of potassium in the fuel particle; the fraction of potassium released at each stage of combustion and the peak rate of release of potassium to gas-phase during combustion. Correlations between these quantities are identified with key trends, patterns and differences highlighted. The analyses provide useful information for the development and validation of modelling of potassium release during combustion of biomass

CO2 gasification of chars prepared from wood and forest residue

The CO2 gasification of chars prepared from Norway spruce and its forest residue was investigated in a thermogravimetric analyzer (TGA) at slow heating rates. The volatile content of the samples was negligible; hence the gasification reaction step could be studied alone, without the disturbance of the devolatilization reactions. Six TGA experiments were carried out for each sample with three different temperature programs in 60 and 100% CO2. Linear, modulated, and constant-reaction rate (CRR) temperature programs were employed to increase the information content available for the modeling. The temperatures at half of the mass loss were lower in the CRR experiments than in the other experiments by around 120 degrees C. A relatively simple, well-known reaction kinetic equation described the experiments. The dependence on the reacted fraction as well as the dependence on the CO2, concentration were described by power functions (n-order reactions). The evaluations were also carried out by assuming a function of the reacted fraction that can mimic the various random pore/random capillary models. These attempts, however, did not result in an improved fit quality. Nearly identical activation energy values were obtained for the chars made from wood and forest residues (221 and 218 kJ/mol, respectively). Nevertheless, the forest residue char was more reactive; the temperatures at half of the mass loss showed 20-34 degrees C differences between the two chars at 10 degrees C/min heating rates. The assumption of a common activation energy, E, and a common reaction order, v, on the CO2, concentration for the two chars had only a negligible effect on the fit quality

The range and level of impurities in CO2 streams from different carbon capture sources

For CO2 capture and storage deployment, the impact of impurities in the gas or dense phase CO2 stream arising from fossil fuel power plants, or large scale industrial emitters, is of fundamental importance to the safe and economic transportation and storage of the captured CO2. This paper reviews the range and level of impurities expected from the main capture technologies used with fossil-fuelled power plants in addition to other CO2 emission-intensive industries. Analysis is presented with respect to the range of impurities present in CO2 streams captured using pre-combustion, post-combustion and oxy-fuel technologies, in addition to an assessment of the different parameters affecting the CO2 mixture composition. This includes modes of operation of the power plant, and different technologies for the reduction and removal of problematic components such as water and acid gases (SOx/NOx). A literature review of data demonstrates that the purity of CO2 product gases from carbon capture sources is highly dependent upon the type of technology used. This paper also addresses the CO2 purification technologies available for the removal of CO2 impurities from raw oxy-fuel flue gas, such as Hg and non-condensable compounds. CO2 purities of over 99% are achievable using post-combustion capture technologies with low levels of the main impurities of N2, Ar and O2. However, CO2 capture from oxy-fuel combustion and integrated gasification combined cycle power plants will need to take into consideration the removal of non-condensables, acid gas species, and other contaminants. The actual level of CO2 purity required will be dictated by a combination of transport and storage requirements, and process economics

Out of the wave: The meaning of suffering and relief from suffering as described in autobiographies by survivors of the 2004 Indian Ocean tsunami

The aim of this study was to explore the meaning of suffering and relief from suffering as described in autobiographies by tourists who experienced the tsunami on 26 December 2004 and lost loved ones. A lifeworld approach, inspired by the French philosopher Merleau-Ponty's phenomenology of perception, was chosen for the theoretical framework. This catastrophe totally changed the survivors' world within a moment. In this new world, there were three main phases: the power of remaining focused, a life of despair, and the unbearable becoming bearable. Life turns into a matter of making the unbearable bearable. Such challenging experiences are discussed in terms of the philosophy of Weil, Jaspers, and Merleau-Ponty. The survivors of the tsunami catastrophe were facing a boundary situation and “le malheur,” the unthinkable misfortune. Even at this lowest level of misfortune, joy is possible to experience. This is part of the survivors' ambivalent experiences of their lifeworld. In this world of the uttermost despair there are also rays of hope, joy, and new life possibilities

Kinetic Behavior of Torrefied Biomass in an Oxidative Environment

The combustion of four torrefied wood samples and their feedstocks (birch and spruce) was studied at slow heating programs, under well-defined conditions by thermogravimetry (TGA). Particularly low sample masses were employed to avoid the self-heating of the samples due to the huge reaction heat of the combustion. Linear, modulated and constant-reaction rate (CRR) temperature programs were employed in the TGA experiments in gas flows of 5 and 20% O2. In this way the kinetics was based on a wide range of experimental conditions. The ratio of the highest and lowest peak maxima was around 50 in the experiments used for the kinetic evaluation. A recent kinetic model of Várhegyi et al. [Energy & Fuels 2012, 26, 1323-1335] was employed with modifications. This model consists of two devolatilization reactions and a successive char burn-off reaction. The cellulose decomposition in the presence of oxygen has a self-accelerating (autocatalytic) kinetics. The decomposition of the non-cellulosic parts of the biomass was described by a distributed activation model. The char burn-off was approximated by power-law (n-order) kinetics. Each of these reactions has its own dependence on the oxygen concentration that was expressed by power-law kinetics, too. The complexity of the applied model reflects the complexity of the studied materials. The model contained 15 unknown parameters for a given biomass. Part of these parameters could be assumed common for the six samples without a substantial worsening of the fit quality. This approach increased the average experimental information for an unknown parameter by a factor of 2 and revealed the similarities in the behavior of the different samples

Towards better prediction of ash related problems in biomass combustion via improved fuel analysis

reportFuture biomass combustion systems should be fuel flexible. To avoid operational problems such as fouling, slagging, fluidized bed agglomeration, and corrosion, the relation between ash behaviour and fuel composition needs to be known. Ash-related problems are strongly coupled to phase transitions. Molten or partly molten ash is sticky and cause furnace-wall slagging, heat exchanger corrosion, or severe bed agglomeration. Vaporisation of ash species leads to fouling in the boiler when ash condenses on heat exchanger tubes. The extent of these phase transitions can be determined based on the chemical composition of the ash. Our search for better prediction tools includes the following four steps. Conventional fuel analyses give the fuel element composition. The bulk fuel element concentrations determine the amount of ash formed and its average composition (1). Element analysis of fuel fractions (i.e. different particle sizes, seams, plant tissues or other distinct fuel components) gives information on the composition of individual ash particles and helps identifying problematic fuel fractions (2). Global equilibrium calculations allow quantification of the problematic ash fractions (3). Kinetic restrictions to the equilibrium (4) can be considered by applying advanced fuel analyses, such as chemical fraction analysis (CFA) or computer-controlled scanning electron microscopy (CC-SEM). Advanced fuel analyses determine the ash-forming matter in the fuel: the mineral, salts and organically associated ash-forming elements. In this paper, these predictions methods are applied on a forest residue fuel fired in Scandinavia

”Jag ska gå och akta mig för att trilla i älven” Om pseudosamordningen gå och verba med sekventiell betydelse i ett konstruktionsgrammatiskt perspektiv.

Denna undersökning handlar om pseudosamordning med gå i förstaledet. Den fokuserar i första hand på de samordningar där relationen mellan verben är sekventiell, d.v.s. att en verbhandling följer temporalt efter den andra. Med utgångspunkt från den kunskap som presenteras i SAG och SO och med hjälp av korpussökningar i språkverktyget Korp karaktäriseras egenskaperna hos nämnda typ av samordning. Arbetet har skett ur ett konstruktionsgrammatiskt (CxG) perspektiv vilket innebär att sekventiella gå och + VP betraktas som en konstruktion med självständig betydelse. Att betydelsen är självständig ska inte tolkas som att den tillkommit oberoende av andra språkliga mönster; enligt CxG är konstruktioner ordnade hierarkiskt och kan ärva egenskaper av varandra. Varje enskild konstruktion är dock självständig i den mening att dess betydelse inte förväntas kunna räknas ut utifrån en generell grammatik och konstruktionens lexikala delar. Undersökningen har resulterat i en sammanställning av sju olika egenskaper som konstruktionen för med sig. Dessa kan sammanfattas i att: gå betyder ’gå iväg’ i konstruktionen och ska betraktas som punktuellt, en specifik plats eller ett område är utsett av subjektet för verbandet, fokus ligger på initialskedet i samordningen, den aktivitet som omtalas i samordningen omtalas i preteritum eller perfekt medan den pågår, andraverbet är agentivt och utförs som en aktivitet under en sammanhållen tid som dessutom är pragmatiskt avgränsad. Den CxG-orienterade slutsatsen är att konstruktionens betydelse kan kopplas till dess lexikala delar men inte räknas ut genom dessa. Även om de drag som presenteras är relaterade till de lexikala enheternas betydelse, är det svårt att tänka sig generella regler som styr hur och när dessa drag överförs från en enhet i samordningen till hela konstruktionen.Specialarbete, 15 hp Svenska språket, fördjupningskurs 1301 Vt 2013 Handledare: Kristian Blensenius och Benjamin Lyngfel

Syntaktisk beskrivning i svenska läromedel - en granskning av begreppen verbfras och predikat i framställningen av grammatik i svenska läromedel

Denna uppsats syftar till att undersöka hur svenska läromedel för gymnasiet definierar begreppen verbfraser och predikat. Följande frågeställningar har använts: Hur beskrivs verbfrasen /predikatet i aktuella läromedel? Finns det problem med beskrivningen? Problem syftar i det här fallet i första hand på beskrivningar som är tvetydiga, motstridiga, begränsade eller strider mot den vetenskapliga norm som Svenska Akademiens grammatik (SAG), i kraft av att vara det dominerande standardverket, får representera i denna uppsats. Nio aktuella läromedel som innehåller grammatikbeskrivningar för gymnasiet har undersökts. Metoden har till största del bestått i en kvantitativ innehållsanalys. Därigenom har beskrivningen i respektive läromedel kunnat presenteras med hjälp av diskreta kategorier. Dessa kategorier anger hur verbfrasen och predikatet förklaras i olika hänseenden och vilka syntaktiska beståndsdelar som beskrivs ingå i dessa. Undersökningen visar att begreppen predikat och verbfras definieras på olika sätt i de olika läromedlen. Inte sällan finns även motstridiga uppgifter om vilka delar av satsen som räknas in i verbfrasen och predikatet i en och samma lärobok. I de läromedel som beskriver båda begreppen uppstår antingen en redundant beskrivning eller två alternativa beskrivningar, vilket i båda fallen bedöms vara förvirrande i denna uppsats. De tre läromedel som inte använder begreppet verbfras har inte samma problem med krockar mellan beskrivningen av verbfrasen och predikatet. De har däremot överlag en grund beskrivning eftersom ingen av dessa heller beskriver strukturen hos andra fraser mer ingående. Slutligen föreslås två alternativa beskrivningar - en mycket platt beskrivning där verbala led anges som huvud i en sats bestående av flera verbelement som knyter olika satsdelar till sig. I en sådan platt beskrivning bedöms även dikotomin mellan subjekt och predikatsled vara onödig. Det andra förslaget på beskrivningsmodell är trogen den som presenteras i SAG. Den senare beskrivningen har ett större förklaringsvärde genom att den tydliggör verben i en verbkedjas relation till varandra men är även mer avancerad. Satsadverbialets funktion blir tydligare i denna beskrivning genom att det framgår i beskrivningen att denna enhet är överordnad verbfrasen. Förslagsvis kan denna modell presenteras som ett sätt att nyansera den tidigare modellen utan att eleverna ska vara tvungna att lära sig använda den fullt ut. I denna uppsats framhålls att ett användande av båda termerna tenderar att leda till krockar i beskrivningen