23 research outputs found

    Comprehensive Secondary Pyrolysis in Fluidized-bed Fast Pyrolysis of Biomass, a Fluid Dynamics Based Modelling Effort

    Get PDF
    Homogenous secondary pyrolysis is category of reactions following the primary pyrolysis and presumed important for fast pyrolysis. For the comprehensive chemistry and fluid dynamics, a probability density functional (PDF) approach is used; with a kinetic scheme comprising 134 species and 4169 reactions being implemented. With aid of acceleration techniques, most importantly Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT), a solution within reasonable time was obtained. More work is required; however, a solution for levoglucosan (C6H10O5) being fed through the inlet with fluidizing gas at 500 oc, has been obtained. 88.6% of the levoglucosan remained non-decomposed, and 19 different decomposition product species were found above 0.01% by weight. A homogenous secondary pyrolysis scheme proposed can thus be implemented in a CFD environment and acceleration techniques can speed-up the calculation for application in engineering settings

    Учебная практика «Медицинский уход» – первая ступень к практикоориентированному обучению в медицинском вузе

    Get PDF
    МЕДИЦИНСКИЕ УЧЕБНЫЕ ЗАВЕДЕНИЯОБРАЗОВАНИЕ МЕДИЦИНСКОЕСТУДЕНТЫ МЕДИЦИНСКИХ УЧЕБНЫХ ЗАВЕДЕНИЙПРАКТИКО-ОРИЕНТИРОВАННЫЙ ПОДХОДПРАКТИКО-ОРИЕНТИРОВАННОЕ ОБУЧЕНИЕУЧЕБНАЯ ПРАКТИКАПРАКТИКА ОБЩАЯУХОД ЗА БОЛЬНЫ

    Influence of reaction atmosphere (H2O, N2, H2, CO2, CO) on fluidized-bed fast pyrolysis of biomass using detailed tar vapor chemistry in computational fluid dynamics

    Get PDF
    Secondary pyrolysis in fluidized bed fast pyrolysis of biomass is the focus of this work. A novel computational fluid dynamics (CFD) model coupled with a comprehensive chemistry scheme (134 species and 4169 reactions, in CHEMKIN format) has been developed to investigate this complex phenomenon. Previous results from a transient three-dimensional model of primary pyrolysis were used for the source terms of primary products in this model. A parametric study of reaction atmospheres (H2O, N2, H2, CO2, CO) has been performed. For the N2 and H2O atmosphere, results of the model compared favorably to experimentally obtained yields after the temperature was adjusted to a value higher than that used in experiments. One notable deviation versus experiments is pyrolytic water yield and yield of higher hydrocarbons. The model suggests a not overly strong impact of the reaction atmosphere. However, both chemical and physical effects were observed. Most notably, effects could be seen on the yield of various compounds, temperature profile throughout the reactor system, residence time, radical concentration, and turbulent intensity. At the investigated temperature (873 K), turbulent intensity appeared to have the strongest influence on liquid yield. With the aid of acceleration techniques, most importantly dimension reduction, chemistry agglomeration, and in-situ tabulation, a converged solution could be obtained within a reasonable time (∼30 h). As such, a new potentially useful method has been suggested for numerical analysis of fast pyrolysis

    Pyrolysis of biomass in fluidized-beds: in-situ formation of products and their applications for ironmaking

    No full text
    The iron and steel industry emitted 8 % of all CO2 emissions in Sweden, 2011. Investigating alternative energy carriers is the purpose of this thesis. By pyrolyzing biomass, an energetic solid, gaseous and liquid (bio oil) fraction is obtained. If pyrolyzing biomass in a fluidized-bed reactor, the highest value may be added to the combined products. Additional understanding of pyrolysis in fluidized beds is pursued, using Computational Fluid Dynamics (CFD) and comprehensive kinetic schemes. The obtained solid product is investigated as a bio-injectant in blast furnaces for ironmaking. A new approach of separately modeling, the primary and secondary pyrolysis, is developed in this thesis. A biomass particle devolatilizes during pyrolysis. Primary pyrolysis is the solid decomposition which results in the volatiles that can leave the particle. Secondary pyrolysis is the decompositions of these volatiles, primarily in the gas phase. The primary pyrolysis (35 species, 15 reactions) mainly occurs in the bed-zone and as such, the model needs to take into account the complex physical interaction of biomass-particles with the fluidizing media (sand) and the fluidizing agent (gas). This is accomplished by representing the components by Eulerian phases and implementing interaction terms, as well as using a Stiff Chemistry Solver for the implemented reactions.  The secondary pyrolysis (not considering heterogeneous reactions), mainly occurs outside the bed zone in one phase. The fluid flow is simpler but the chemistry is more complex, with a larger variety of molecules emerging. Carrying out the simulations time-effectively, for the secondary pyrolysis (134 species, 4169 reactions) is accomplished by using Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT); in a Probability Density Functional (PDF) framework. An analysis of the numerical results suggest that they can be matched adequately with experimental measurements, considering pressure profiles, temperature profiles and the overall yield of gas, solid and liquid products. Also, with some exceptions, the yield of major and minor gaseous species can be matched to some extent. Hence, the complex physics and chemistry of the integrated process can be considered fairly well-considered but improvements are possible. A parametric study of reaction atmospheres (or fluidizing agents), is pursued as means of understanding the process better. The models revealed significant effects of the atmosphere, both physically (during the primary and secondary pyrolysis) and chemically (during secondary pyrolysis). During primary pyrolysis, the physical influence of reaction atmospheres (N2, H2O) is investigated. When comparing steam to nitrogen, heat flux to the biomass particles, using steam, is better distributed on a bed level and on a particle level. During secondary pyrolysis, results suggest that turbulence interaction plays an important role in accelerating unwanted decomposition of the liquid-forming volatiles. Steam, which is one of the investigated atmospheres (N2, H2O, H2, CO, CO2), resulted in a lower extent of unwanted secondary pyrolysis. Altough, steam neither resulted in the shortest vapor residence time, nor the lowest peak temperature, nor the lowest peak radical concentration; all factors known to disfavor secondary pyrolysis. A repeated case, using a high degree of turbulence at the inlet, resulted in extensive decompositions. The attractiveness of the approach is apparent but more testing and development is required; also with regards to the kinetic schemes, which have been called for by several other researchers. The solid fraction after pyrolysis is known as charcoal. Regarding its use in blast furnaces; modelling results indicate that full substitution of fossil coal is possible. Substantial reductions in CO2 emissions are hence possible. Energy savings are furthermore possible due to the higher oxygen content of charcoal (and bio-injectants in general), which leads to larger volumes of blast furnace gas containing more latent energy (and less non-recoverable sensible energy). Energy savings are possible, even considering additional electricity consumption for oxygen enrichment and a higher injection-rate on energy basis. A survey of biomass availability and existing technology suppliers in Sweden, suggest that all injection into Blast furnace M3 in Luleå, can be covered by biomass. Based on statistics from 2008, replacement of coal-by-charcoal from pyrolysis could reduce the on-site carbon dioxide emissions by 28.1 % (or 17.3 % of the emissions from the whole industry). For reference, torrefied material and raw biomass can reduce the on-site emissions by 6.4 % and 5.7 % respectively.Järn och stålindustrin stod för 8 % av alla koldioxidutsläpp i Sverige, 2011. Alternativa energibärare undersöks i denna avhandling. Genom pyrolys av biomassa, fås en energirik fast produkt, och samtidigt en gasformig och en vätskeformig produkt (bio-olja). Om en fluidbäddsreaktor används kan största möjliga mervärde tillföras de kombinerade produkterna. Djupare förståelse för pyrolys i fluidbäddar har eftersträvats med hjälp fluiddynamikberäkningar (CFD) och detaljerade kinetikscheman. Den fasta produkten har undersökts som bio-injektion i masugnar. En ny approach för modellering av primär och sekundär pyrolys separat, har utvecklats i denna avhandling. En biomassapartikel avflyktigas under pyrolys. Primär pyrolys är nedrytningen av den fasta biomassan till intermediärer (flyktiga ämnen) som kan lämna partikeln. Sekundärpyrolys är nedbrytning av dessa flyktiga ämnen, som primärt sker i gasfas. Primärpyrolysen (i detta arbete, 35 ämnen och 15 reaktioner) sker mestadels i bäddzonen och därmed behöver modellen ta hänsyn till den komplexa fysiska interaktionen av biomassapartiklarna med fluidbäddsmediet (sand) och fluidiseringsgasen. Detta åstadkoms med hjälp av Euleriska faser och interaktionstermer, samt en lösare för hantering av styva reaktionssystem. Sekundärpyrolysen sker huvudsakligen utanför bäddzonen. Fluiddynamiken är enklare men kemin är mer komplex, med fler ämnen närvarande. Att tidseffektivt köra beräkningarna, för sekundärpyrolysen (134 ämnen, 4169 reaktioner) åstadkoms med hjälp Dimensionsreducering, Kemiagglomerering och In-situtabulering (ISAT); som implementerats i en sannolikhetstäthetsfunktion (PDF). En analys av de numeriska beräkningarna antyder att de kan matchas med experimentella resultat, med avseende på tryckprofil, temperaturprofil, utbyte av gasformiga, fasta och vätskeformiga produkter. Dessutom, med några undantag, kan beräkningarna matchas ganska väl med de viktigaste gasformiga produkterna. Därmed kan de huvudsakliga fysiska och kemikaliska mekanismerna representeras av modellen men förbättringar är givetvis möjliga. En parameterstudie av reaktionsatmosfärer (dvs fluidiseringsgaser) genomfördes, för att förstå processen bättre. Modellen visade på betydande effekter av atmosfären, fysisk (både under primär och sekundärpyrolys), och kemiskt (under sekundärpyrolysen).   Under primärpyrolysen undersöktes den fysiska inverkan av reaktionsatmosfärer (N2, H2O). När ånga jämfördes med kvävgas, visade det sig att värmeflödet sker mer homogent på både bäddnivå och på partikelnivå, med ångatmosfär. Under sekundärpyrolysen, så antyder resultaten på att turbulensinteraktion spelar en viktig roll för accelererad oönskad sekundärpyrolys av de vätskebildande ämnena. Ånga som är en av de undersökta atmosfärerna (N2, H2O, H2, CO, CO2), resulterade i den lägsta omfattningen av sekundärpyrolys. Dock så ledde en ångatmosfär varken till den lägsta residenstiden, den lägsta peaktemperaturen eller den lägsta radikalkoncentrationen; som alla normalt motverkar sekundärpyrolysen. Ett repeterat case, med hög turbulens i inloppet, gav betydande sekundärpyrolys av de vätskebildande ämnena. Attraktiviteten av approachen är given men mer testning och utveckling behövs, som också påkallats av andra forskare. Den fasta produkten efter pyrolys kallas träkol. Angående dess applicering i masugnar, så visar modelleringsresultaten att full substitution av fossilt kol går att göra. Betydande minskningar i koldioxidutsläpp är därmed möjliga. Energibesparingar är dessutom möjligt, tack vare det höga syreinnehållet i träkol (och biobränslen generellt), vilket ger större volymer av masugnsgas med högre värmevärde (och mindre sensibel värme som inte är utvinnbar). Energibesparingar är möjliga även om hänsyn tas till högre eleffekt för syrgasanrikning i blästerluften och en högre injektionsåtgång på energibasis. En översikt över biomassatillgången och existerande teknikleverantörer i Sverige, indikerar att all injektion i Masugn 3 (i Luleå) kan ersättas med biomassa. Baserat på statistik från 2008, så kan ersatt kol med träkol, minska de platsspecifika koldioxidutsläppen med 28.1 % (eller 17.3 % av alla utsläpp från stålindustrin). Som jämförelse kan torrifierad biomassa and obehandlad biomassa reducera utsläppen med 6.4 % respektive 5.7 %.QC 20150827</p

    Pyrolysis of biomass in fluidized-beds: in-situ formation of products and their applications for ironmaking

    No full text
    The iron and steel industry emitted 8 % of all CO2 emissions in Sweden, 2011. Investigating alternative energy carriers is the purpose of this thesis. By pyrolyzing biomass, an energetic solid, gaseous and liquid (bio oil) fraction is obtained. If pyrolyzing biomass in a fluidized-bed reactor, the highest value may be added to the combined products. Additional understanding of pyrolysis in fluidized beds is pursued, using Computational Fluid Dynamics (CFD) and comprehensive kinetic schemes. The obtained solid product is investigated as a bio-injectant in blast furnaces for ironmaking. A new approach of separately modeling, the primary and secondary pyrolysis, is developed in this thesis. A biomass particle devolatilizes during pyrolysis. Primary pyrolysis is the solid decomposition which results in the volatiles that can leave the particle. Secondary pyrolysis is the decompositions of these volatiles, primarily in the gas phase. The primary pyrolysis (35 species, 15 reactions) mainly occurs in the bed-zone and as such, the model needs to take into account the complex physical interaction of biomass-particles with the fluidizing media (sand) and the fluidizing agent (gas). This is accomplished by representing the components by Eulerian phases and implementing interaction terms, as well as using a Stiff Chemistry Solver for the implemented reactions.  The secondary pyrolysis (not considering heterogeneous reactions), mainly occurs outside the bed zone in one phase. The fluid flow is simpler but the chemistry is more complex, with a larger variety of molecules emerging. Carrying out the simulations time-effectively, for the secondary pyrolysis (134 species, 4169 reactions) is accomplished by using Dimension Reduction, Chemistry Agglomeration and In-situ Tabulation (ISAT); in a Probability Density Functional (PDF) framework. An analysis of the numerical results suggest that they can be matched adequately with experimental measurements, considering pressure profiles, temperature profiles and the overall yield of gas, solid and liquid products. Also, with some exceptions, the yield of major and minor gaseous species can be matched to some extent. Hence, the complex physics and chemistry of the integrated process can be considered fairly well-considered but improvements are possible. A parametric study of reaction atmospheres (or fluidizing agents), is pursued as means of understanding the process better. The models revealed significant effects of the atmosphere, both physically (during the primary and secondary pyrolysis) and chemically (during secondary pyrolysis). During primary pyrolysis, the physical influence of reaction atmospheres (N2, H2O) is investigated. When comparing steam to nitrogen, heat flux to the biomass particles, using steam, is better distributed on a bed level and on a particle level. During secondary pyrolysis, results suggest that turbulence interaction plays an important role in accelerating unwanted decomposition of the liquid-forming volatiles. Steam, which is one of the investigated atmospheres (N2, H2O, H2, CO, CO2), resulted in a lower extent of unwanted secondary pyrolysis. Altough, steam neither resulted in the shortest vapor residence time, nor the lowest peak temperature, nor the lowest peak radical concentration; all factors known to disfavor secondary pyrolysis. A repeated case, using a high degree of turbulence at the inlet, resulted in extensive decompositions. The attractiveness of the approach is apparent but more testing and development is required; also with regards to the kinetic schemes, which have been called for by several other researchers. The solid fraction after pyrolysis is known as charcoal. Regarding its use in blast furnaces; modelling results indicate that full substitution of fossil coal is possible. Substantial reductions in CO2 emissions are hence possible. Energy savings are furthermore possible due to the higher oxygen content of charcoal (and bio-injectants in general), which leads to larger volumes of blast furnace gas containing more latent energy (and less non-recoverable sensible energy). Energy savings are possible, even considering additional electricity consumption for oxygen enrichment and a higher injection-rate on energy basis. A survey of biomass availability and existing technology suppliers in Sweden, suggest that all injection into Blast furnace M3 in Luleå, can be covered by biomass. Based on statistics from 2008, replacement of coal-by-charcoal from pyrolysis could reduce the on-site carbon dioxide emissions by 28.1 % (or 17.3 % of the emissions from the whole industry). For reference, torrefied material and raw biomass can reduce the on-site emissions by 6.4 % and 5.7 % respectively.Järn och stålindustrin stod för 8 % av alla koldioxidutsläpp i Sverige, 2011. Alternativa energibärare undersöks i denna avhandling. Genom pyrolys av biomassa, fås en energirik fast produkt, och samtidigt en gasformig och en vätskeformig produkt (bio-olja). Om en fluidbäddsreaktor används kan största möjliga mervärde tillföras de kombinerade produkterna. Djupare förståelse för pyrolys i fluidbäddar har eftersträvats med hjälp fluiddynamikberäkningar (CFD) och detaljerade kinetikscheman. Den fasta produkten har undersökts som bio-injektion i masugnar. En ny approach för modellering av primär och sekundär pyrolys separat, har utvecklats i denna avhandling. En biomassapartikel avflyktigas under pyrolys. Primär pyrolys är nedrytningen av den fasta biomassan till intermediärer (flyktiga ämnen) som kan lämna partikeln. Sekundärpyrolys är nedbrytning av dessa flyktiga ämnen, som primärt sker i gasfas. Primärpyrolysen (i detta arbete, 35 ämnen och 15 reaktioner) sker mestadels i bäddzonen och därmed behöver modellen ta hänsyn till den komplexa fysiska interaktionen av biomassapartiklarna med fluidbäddsmediet (sand) och fluidiseringsgasen. Detta åstadkoms med hjälp av Euleriska faser och interaktionstermer, samt en lösare för hantering av styva reaktionssystem. Sekundärpyrolysen sker huvudsakligen utanför bäddzonen. Fluiddynamiken är enklare men kemin är mer komplex, med fler ämnen närvarande. Att tidseffektivt köra beräkningarna, för sekundärpyrolysen (134 ämnen, 4169 reaktioner) åstadkoms med hjälp Dimensionsreducering, Kemiagglomerering och In-situtabulering (ISAT); som implementerats i en sannolikhetstäthetsfunktion (PDF). En analys av de numeriska beräkningarna antyder att de kan matchas med experimentella resultat, med avseende på tryckprofil, temperaturprofil, utbyte av gasformiga, fasta och vätskeformiga produkter. Dessutom, med några undantag, kan beräkningarna matchas ganska väl med de viktigaste gasformiga produkterna. Därmed kan de huvudsakliga fysiska och kemikaliska mekanismerna representeras av modellen men förbättringar är givetvis möjliga. En parameterstudie av reaktionsatmosfärer (dvs fluidiseringsgaser) genomfördes, för att förstå processen bättre. Modellen visade på betydande effekter av atmosfären, fysisk (både under primär och sekundärpyrolys), och kemiskt (under sekundärpyrolysen).   Under primärpyrolysen undersöktes den fysiska inverkan av reaktionsatmosfärer (N2, H2O). När ånga jämfördes med kvävgas, visade det sig att värmeflödet sker mer homogent på både bäddnivå och på partikelnivå, med ångatmosfär. Under sekundärpyrolysen, så antyder resultaten på att turbulensinteraktion spelar en viktig roll för accelererad oönskad sekundärpyrolys av de vätskebildande ämnena. Ånga som är en av de undersökta atmosfärerna (N2, H2O, H2, CO, CO2), resulterade i den lägsta omfattningen av sekundärpyrolys. Dock så ledde en ångatmosfär varken till den lägsta residenstiden, den lägsta peaktemperaturen eller den lägsta radikalkoncentrationen; som alla normalt motverkar sekundärpyrolysen. Ett repeterat case, med hög turbulens i inloppet, gav betydande sekundärpyrolys av de vätskebildande ämnena. Attraktiviteten av approachen är given men mer testning och utveckling behövs, som också påkallats av andra forskare. Den fasta produkten efter pyrolys kallas träkol. Angående dess applicering i masugnar, så visar modelleringsresultaten att full substitution av fossilt kol går att göra. Betydande minskningar i koldioxidutsläpp är därmed möjliga. Energibesparingar är dessutom möjligt, tack vare det höga syreinnehållet i träkol (och biobränslen generellt), vilket ger större volymer av masugnsgas med högre värmevärde (och mindre sensibel värme som inte är utvinnbar). Energibesparingar är möjliga även om hänsyn tas till högre eleffekt för syrgasanrikning i blästerluften och en högre injektionsåtgång på energibasis. En översikt över biomassatillgången och existerande teknikleverantörer i Sverige, indikerar att all injektion i Masugn 3 (i Luleå) kan ersättas med biomassa. Baserat på statistik från 2008, så kan ersatt kol med träkol, minska de platsspecifika koldioxidutsläppen med 28.1 % (eller 17.3 % av alla utsläpp från stålindustrin). Som jämförelse kan torrifierad biomassa and obehandlad biomassa reducera utsläppen med 6.4 % respektive 5.7 %.QC 20150827</p

    Processing of biomass to Hydrocarbons – using a new catalytic steam pyrolysis route

    No full text
    Obtaining renewable transportation fuel has been identified as one of the main challenges for a sustainable society. Catalytic pyrolysis followed by hydrotreatment has been demonstrated as one possible route for producing transportation fuels. Using steam in this process could have a number of benefits as given by our research effort. For this paper, we will show that a catalyst together with steam prolongs the activity of the catalyst by preventing coking. This means that both steam and catalyst mutually benefits the deoxygenation. The presented mass and energy balance shows that up to 40% of the calorific value of biomass remains in the deoxygenated oil, on dry basis. This is in contrast to the mass yield, which for the same case was 25%; meaning that the oil is of significantly higher quality with a high content of hydrocarbons. In addition, CFD studies have shown steam is able to redistribute the heat flux and provide more uniform operating conditions compared to for example nitrogen. In conclusion, this route using steam shows promise for displacing fossil transportation fuels, by upgrading of the liquid in existing refineries or next-generation bio refineries. In additional support of this, we have published a number of papers describing conventional fast pyrolysis using steam, CFD modeling for further understanding and experimental work using a combination of steam and firstly a bimetallic catalyst (Ni, V) then a metal modified HZSM5 catalyst (Ni, V, Zeolite, Binder). This paper connects all these individual studies and provides further understanding of the role of steam and the role of steam in combination with a catalyst, in the fast pyrolysis process.QC 20150305</p

    Spreadability Testing of Powder for Additive Manufacturing

    No full text
    The spreading of powders into thin layers is a critical step in powder bed additive manufacturing, but there is no accepted technique to test it. There is not even a metric that can be used to describe spreading behaviour. A robust, image-based measurement procedure has been developed and can be implemented at modest cost and with minimal training. The analysis is automated to derive quantitative information about the characteristics of the spread layer. The technique has been demonstrated for three powders to quantify their spreading behaviour as a function of layer thickness and spreading speed.QC 20210916</p

    Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces

    No full text
    Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C. One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na2O (3.5%) and K2O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered. Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries.QC 20140107Förnybar

    Methodology for identification of wet areas in agricultural lands using remote sensing data

    No full text
    Maģistra darba mērķis ir izvērtēt lāzerskenēšanas datu un multispektrālo satelītainu izmantošanu pārmitru lauksaimniecības zemju identificēšanā, izstrādājot metodiku digitālā reljefa modeļa un dažādu spektru satelītainu apstrādē un kombinēšanā, lai izveidotu prognostisko modeli rastra kartes formātā. Pētījuma teritorijas veido 12 lauksaimniecības zemes Latvijas centrālajā un rietumu daļā, kuras ir uz dažādiem kvartāra nogulumu tipiem, ar dažādu zemes lietojuma veidu un meliorācijas stāvokli. Dati prognostiskā modeļa izveidošanai tika iegūti no 200 parauglaukumiem 10 pētījuma teritorijās un analizēti, izmantojot lineārās regresijas modeli. Kombinējot datu slāņus ar labākajiem rezultātiem lineārā vienādojumā, tika izstrādāts augsnes mitruma apstākļu prognostiskais modelis, kurš ar izstrādāto pētījuma metodiku sasniedz 66% kopējo pareizību. Pētījuma gaitā tika iegūtas arī vērtīgas atziņas un priekšlikumi metodikas uzlabošanai, lai nākotnē varētu pilnvērtīgi izmantot attālās izpētes datu avotus pārmitro lauksaimniecības zemju identificēšanai Latvijas apstākļos.Aim of this master's thesis is to evaluate the use of laser scanning data and multispectral satellite images for identification of local wet areas in agriculture lands by developing a methodology for processing digital elevation models and different spectrum satellite images to create a prognostic model in the form of a raster map. The areas of this study consists of 12 agricultural lands in the central and western part of Latvia, which are on different types of Quaternary sediments, with a different type of land use and an amelioration network functional condition. Data for the development of a prognostic model was collected from 200 sample plots in 10 study sites and analysed using a linear regression model. Combining the data layers with the best results in a linear equation, a prognostic model of soil wetness conditions was developed, reaching a total accuracy of 66% with developed study methodology. This study helps to focus different aspects of remote sensing data usage and methodology for future improvements to fully implement remote sensing methods for identification of wet areas in agricultural lands in Latvia

    Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces

    No full text
    ABSTRACT Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C. One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO 2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na 2 O (3.5%) and K 2 O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered. Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries
    corecore