This thesis focuses on the analysis of kinetics of i) low-temperature pyrolysis of gaseous hydrocarbons, ii) high-temperature steam gasification of char of wood pellets (&gt;700oC), iii) high temperature pyrolysis of straw pellets in an atmosphere of argon and steam, and iv) high temperature pyrolysis of slices of transversally cut wooden sticks. The results of the kinetic measurements in the high-temperature cases are approximated using a least-square based optimization software, which was specially developed to analyse kinetics prone for deviation from the Arrhenius law.In the thesis a general analysis of the researched materials and kinetics of their pyrolysis and gasification is presented from the self-organization perspective. The energy transfer phenomena in both the pyrolysis and gasification processes of biomass are discussed with an emphasis on an analysis of basic phenomena involving the self-organized dynamics on fractal structures in the chosen biomass samples. / <p>QC 20150324</p>

Idag är fossila bränslen fortfarande de främsta energikällorna runt om i världen. Enligt många experter kommer snart inte produktionen kunna tillfredsställa efterfrågan av olja. Därför bör övergången till alternativa bränslen ske så fort som möjligt. Det biobränsle som tillverkas mest i Sverige är pellets där Stora Enso på Gruvön är en tillverkare. Det är dock energikrävande att tillverka eldningsbar pellets från fuktigt spån och Stora Enso vill därför spara energi vid tillverkningen. Målet är att analysera och kartlägga energianvändningen i varje delprocess i pelletstillverkningen. Genom en energikartläggning kan möjliga energieffektiviseringar hittas. Nyckeltal tas fram för varje energislag och delprocess för att kunna kvantifieras energianvändningen och besparingsmöjligheterna. Resultaten visar att den totala energianvändningen uppgår till 1,29 MWh/ton pellets, mätt i torrsubstans. Torkningen är den delprocess som använder mest energi, men också den process som potentiellt går att spara mest energi med värmeåtervinning. Den totala potentiella värmeåtervinningen av utflödesluft för hela processen är 1,17 MWh/ton pellets. Resultaten visar pelletstillverkningens energianvändning och vart fokus ska läggas vid eventuella energibesparande åtgärder och effektiviseringar.

Under de senaste årtiondena har efterfrågan av pellets ökat. Produktion av pellets är en energikrävande process där torkning av sågspån är den del som kräver mest energi. Därför behövs, av ekonomiska och miljömässiga skäl, att energieffektiva lösningar skapas. I denna rapport studeras en möjlig effektiviserad energianvändning genom att ett befintligt värmekraftverk integreras med en anläggning för produktion av pellets. Värme till torkningen av sågspån tas i form av ånga och rökgaser ifrån Åmotfors energis värmekraftverk. Fyra olika torktekniker av sågspån studeras där antingen luft eller ånga används som torkmedium. Två av de studerade fallen är ångtorkar, den ena använder värme i form av ånga vid 24 bars övertryck och den andra använder ånga vid 6 bars övertryck. Den tork som använder luft som torkmedium är en bäddtork. Ånga vid atmosfärstryck och rökgaser används för att värma upp uteluft till torken. Den fjärde torken är anpassad för att ge hög pelletsproduktion samtidigt som den är anpassad till de befintliga ångflöden som finns i värmekraftverket. Den använder både en bäddtork och en ångtork till torkning av sågspån. Målet med rapporten är att öka förståelsen kring tekniska begränsningar och möjligheter för olika torktekniker samt att avgöra vilken av de fyra studerade torktekniksfallen som är lämpligast vid en integrering. Resultaten tas fram med hänsyn till fyra faktorer: pellets-produktion, elproduktion, integrering och dimensionering av tork samt ekonomi. Där tyngdpunkten ligger på pelletsproduktionen i form av mängd tillverkad pellets per år och elproduktion i form av förändrad elproduktion per år efter integreringen. Dimensionering av tork används för att visa på vilka integreringar som kräver störst värmeväxlingsyta samt används till resultat och diskussion för ekonomi. Den ekonomiska utvärderingen avser att ge en fingervisning på vilken integrering som får högst/lägst investeringskostnad samt vilken som får kortast/längst återbetalningstid. Resultaten visar på att ångtorken med 24 bars värmeånga gav den högsta pellets-produktionen på nästan 250 000 ton/år, den kombinerade bädd och ångtorken fick näst högst pelletsproduktion på drygt 180 000 ton/år. Lägst pelletsproduktion fick bäddtorken.    Alla integreringar med en ångtork gav en minskad elproduktion, medan fallet med en bäddtork gav en ökad elproduktion. Störst minskning i elproduktion gav ångtorken med värmeånga på 24 bar. Ekonomiskt var bäddtorken den integrering som hade lägst investeringskostnad men näst högst återbetalningstid på 5,7 år. Ångtorken med värmeånga på 24 bar hade den högsta investeringskostnaden men kortast återbetalningstid på 3,7 år. Beräkningarna på pelletsproduktionen visar på stora skillnader beroende på ifall det är en ångtork eller bäddtork som integreras. Ångtorkarna ger en hög pelletsproduktion och två av fallen ger en pelletsproduktion som skulle vara den högsta i Sverige. För elproduktionen blir resultaten de motsatta där ångtorkarna ger en minskad elproduktion och bäddtorken en ökad. Ångtorken med 6 bars övertryck och den kombinerade ång- och bäddtorken får den största minskningen i elproduktion då elproduktionen från lågtrycksturbinen helt försvinner. Beräkningar på torkarnas värmeväxlingsytor gav ett underlag för vidare beräkningar och diskussion kring ekonomi men än viktigare gav det en fördjupad förståelse i torkarnas uppbyggnad och teknik.   De ekonomiska beräkningarna tar inte hänsyn till vissa faktorer så som ombyggnationer i det befintliga värmekraftverket samt kostnader för lager och värmeväxlare. Dessa faktorer tillsammans med att ekonomiekvationerna på ångtorkarna inte är helt anpassade till denna rapport gör att de är skapade för att användas som fingervisningar på ungefärliga skillnader i kostnader. Beroende på vilket faktor (pelletsproduktion, elproduktion, integrering eller ekonomi) som anses vara viktigast blir valet av fall olika. Ifall en hög pelletsproduktion anses vara av störst värde skall ångtorken med 24 bar övertryck eller den kombinerade bädd och ångtorken väljas. Om däremot elproduktionen värderas högst bör bäddtorken väljas, den är även det fall som kräver minst ombyggnationer av det befintliga värmekraftverket vid en integrering. Ekonomiskt så har bäddtorken den lägsta investeringskostnaden medan de två fall med högst pelletsproduktion ger den kortaste återbetalningstiden. / During the recent decades the demand of pellets has increased. Production of pellets is an energy intensive process where drying of sawdust is the part that requires the most energy. In production of pellets energyefficient solutions needs to be created to achieve better environmental and economical results. This report studies a possible energy efficient solution of integration between an existing thermal power plant and a pellets production unit. Heat for the dryers is extracted from Åmotfors energi’s thermal power plant in the form of steam and flue gas. Four different drying techniques are studied where either air or steam are used as a drying medium. Two of the cases are steam dryers where one uses heat from steam at 24 bar overpressure and the other uses heat from steam at 6 bar overpressure. The dryer using air as the drying medium is a conveyor dryer where steam at atmospheric pressure, and flue gases is used to heat air for the dryer. The fourth dryer is designed to provide a high production of pellets while being adapted to the existing flows of steam in the power plant. It uses both a conveyor dryer and a steam dryer for drying sawdust. The objective of this report is to improve the understanding of technical limitations and possibilities for different drying techniques as well as to determine which of the four studied drying techniques is most suitable for an integration. The results are evaluated with respect to four factors: pellet production, power generation, integration and dimension of the dryers and economy. The focus is on pellets output in terms of quantity produced pellets per year and changes in the electricity generation. Design of drying is used to indicate those integrations that require the greatest heat exchange surface and is used for results and discussion for economics. Economy is calculated as an indicator on which integration that gets the highest/lowest investment cost and which one gets longest/shortest payback time. The results show that the steam dryer with 24 bar steam provided the highest pellet production of over 200 000 tonnes / year, the combined conveyer and steam dryer got the second highest pellet production of almost 200 000 tonnes / year. The conveyor dryer got the lowest production of pellets. All integrations with a steam dryer resulted in a reduced total production of electricity per year, while the case with an conveyor dryer increased the electricity production. The steam dryer with steam at 24 bar gave the greatest reduction in electricity production. Conveyor dryer was the integration that gave the lowest investment cost but the second highest payback time of 5.7 years. The steam dryer with steam at 24 bar had the highest investment cost but the shortest payback time of 3.7 years.        The calculations of pellet production show large differences depending on whether it is a steam dryer or conveyor dryer that is integrated. Steam dryers provide a high pellet production and two of them provide a pellet production which would be the highest in Sweden. For electricity generation, the results are the opposite where steam dryers provide a reduction in electricity and for conveyor dryer it increased. The steam dryer with steam at 6 bars and the combined steam- and conveyor dryer shows the greatest reduction in electricity production because electricity generation from the low pressure turbine ceases. Calculations on the dryer's heat exchanging surface provided a basis for further calculations and discussion about the economy but more importantly it gave a deeper understanding of the design and technology behind the dryers. The financial calculations do not take into account certain factors such as the rebuilding of the existing thermal power plant and the cost of storage warehouse and heat exchangers. These factors, as well as the equations of steam dryers investment cost are not perfectly suited to this report makes the financial result more of an indicator of the cost differences between the dryers. Depending on which of the factors is considering to be most important, pellets production, power generation, integration or economic, the choice of which integration will be most preferable differs. If a high pellet production is considered to be of greatest value, the steam dryer with steam at 24 bars or the combined conveyor and the steam dryer should be selected. However, if the electricity is valued to be more important the conveyor dryer should be selected, it is also the case that requires a minimum of rebuilding of the existing thermal power plant. Economically the conveyor dryer has the lowest investment cost while the two cases with a maximum pellet production provides the shortest payback time.

Diss. (sammanfattning) Örebro : Univ., 2008. / Härtill 4 uppsatser.

Orientador: Raul Cesar Evangelista / Banca: Letícia Norma Carpentiere Rodrigues / Banca: Osvaldo de Freitas / Banca: Marlus Chorilli / Banca: Ana Dóris de Castro / Resumo: O desenvolvimento de formas farmacêuticas administradas pela via oral e utilizadas para liberação colônica de fármacos, visando o tratamento local de doenças inflamatórias intestinais, tem sido bastante estudado. Com essa finalidade, no presente trabalho foram preparados pellets de metronidazol (MT), constituídos ou não de quitosana (QS) e revestidos com QS, ftalato de hidroxipropilmetilcelulose (HPMCP), Kollicoat MAE® e Kollicoat SR®. Os pellets foram preparados por extrusão-esferonização e revestidos em leito fluidizado. Três delineamentos experimentais foram planejados com a finalidade de se definir as formulações a serem preparadas e analisadas. Os pellets e seus constituintes foram analisados por espectrofotometria no IV e por análise térmica, para verificação de possíveis interações entre o fármaco e o excipiente. A morfologia dos pellets foi analisada através de estereoscópio e por microscopia eletrônica de varredura. Outras análises incluíram área superficial, granulometria, densidade e grau de intumescimento. Também foi realizada a liberação in vitro do fármaco durante 8 horas, utilizando-se os Aparatos I e III da Farmacopéia Americana, e análise de absorção intestinal pela técnica do saco intestinal invertido. As análises térmica e espectrofotométrica por IV revelaram que não há interações físico-químicas entre o MT e os demais componentes dos pellets. A análise morfológica revelou que os pellets são esféricos; as análises de área superficial e microscopia eletrônica de varredura mostraram que o processo de revestimento não foi eficaz para algumas amostras, pois apresentaram poros em suas estruturas. Os pellets também foram analisados quanto à capacidade de intumescimento, demonstrando que a presença de QS acentua o grau de intumescimento das amostras... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The development of oral administered dosage forms used for colonic drug delivery aiming the local treatment of intestinal inflammatory diseases has been well studied. Thus, in the present work metronidazol (MT)-containing pellets, constituted or not by chitosan (QS) and covered with QS, hydroxypropyl methylcellulose phtalate (HPMCP), Kollicoat MAE® and Kollicoat SR® were developed. The pellets were prepared by extrusion-spheronization and covered on fluidized bed. Three experimental designs were used to define the formulations to be prepared and analyzed. The pellets and their constituents were analyzed by IR spectrophotometry and thermal analysis, in order to assess possible interactions between the drug and the excipients. Pellets' morphology was verified under a stereoscope and by means of scanning electronic microscopy. Other analyses included surface area, size distribution, density and degree of swelling. In vitro drug release, using Apparatuses I and III of United States Pharmacopoeia, and the assay of intestinal absorption by the everted gut sac technique were also carried out. Both thermal and IR spectrophotometric analyses revealed no physicochemical interactions between MT and the other constituents of the pellets. Morphological analyses showed that the pellets have spherical shape. The covering process was not efficient for some samples, since it was possible to identify pores on their surfaces, as assessed by surface area determination and scanning electronic microscopy. The presence of QS increased the swelling ratio. The in vitro ability of the pellets to reach colonic conditions, after resisting against gastric and enteric environments was also demonstrated. Firstly, it was observed that most of the drug was released in gastric medium from uncovered pellets or from those covered with QS or HPMCP, mainly due to the defects observed in such coatings... (Complete abstract click electronic access below) / Doutor

O objetivo deste trabalho foi desenvolver formulações de pellets contendo teofilina, utilizando a goma gelana como aglutinante. Inicialmente, o uso desse polímero foi avaliado em comparação com o PVP. Por meio de delineamento experimental 32 foram analisadas as variáveis aglutinante e diluente. Os pellets obtidos apresentaram resultados satisfatórios na friabilidade e esfericidade. Verificou-se que o diluente exerceu influência significativa na granulometria, de modo que formulações com manitol apresentaram maior formação de pó após a produção. Com relação ao aglutinante sua maior influência foi na dissolução, pois formulações com gelana apresentaram eficiência de dissolução, em média, menor que as formulações com PVP. A seguir, foi avaliada a influência do polímero, sua quantidade, e seu modo de incorporação nas formulações. Para isso foi realizado um delineamento experimental 23, tendo a gelana, a quantidade, e a incorporação como variáveis. Verificou-se que a característica que sofreu maior influência das variáveis foi a granumoletria, pois as condições empregadas influenciaram significativamente o rendimento de pellets. Com relação à friabilidade, esfericidade e dissolução, não foram observadas diferenças significativas entre os resultados, ainda que algumas tendências puderam ser identificadas. / Aim of this work was to develop pellet formulations containing theophylline, using gellan gum as a binding agent. Inicially, application of the polymer was compared with PVP. By a 32 experimental design, variables binder and diluent were analyzed. Pellets presented satisfactory results in friability and sphericity. It was found that the diluent exerted significant influence on granulometry, so formulations with mannitol showed higher dust formation after production. Regarding binder variable, its higher influence was in the dissolution, since formulations with gellan presented smaller dissolution efficiency than formulations with PVP. Next, the influence of polymer, amount, and incorporation were evaluated. In this part, a 23 experimental design was carried out, with gellan, quantity, and incorporation as variables. It was found that granulometry was the most influenced by variables. So conditions employed influenced significantly the yield of pellets. Regarding friability, sphericity and dissolution, no significant differences were observed, although some trends could be identified.

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2015-12-01T13:29:47Z No. of bitstreams: 1 texto completo.pdf: 582958 bytes, checksum: f4d06082051cb8501b00982af600af18 (MD5) / Made available in DSpace on 2015-12-01T13:29:47Z (GMT). No. of bitstreams: 1 texto completo.pdf: 582958 bytes, checksum: f4d06082051cb8501b00982af600af18 (MD5) Previous issue date: 2014-12-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O desenvolvimento da produção de pellets no Brasil é promissor devido ao crescente consumo mundial de pellets. Contudo, há poucos estudos sobre peletização no país. O Artigo I teve como objetivo avaliar as propriedades da matéria-prima e de pellets produzidos com diferentes biomassas brasileiras. Foram utilizadas biomassas florestais (madeira, casca e ponteira de eucalipto e madeira de Pinus) e agrícolas (resíduos de algodoeiro, bagaço de cana-de-açúcar, capim-elefante e palha de arroz). Determinaram- se propriedades físicas, mecânicas e químicas das diferentes biomassas e dos pellets produzidos, os quais foram classificados segundo normas de comercialização europeias. Dentre as biomassas florestais, os pellets de madeira de Pinus destacaram-se em relação aos demais, devido ao maior poder calorífico útil e menor teor de cinzas. Dentre as biomassas agrícolas, o bagaço apresentou as propriedades mais favoráveis para a produção de pellets. O Artigo II objetivou avaliar a influência da adição de lignina kraft nas propriedades de pellets de eucalipto. A matéria-prima utilizada para produção de pellets foi madeira com casca de um clone de Eucalyptus grandis x Eucalyptus urophylla, além de 10 % de resíduos da colheita do eucalipto. Excluindo-se a testemunha (0% de lignina), adicionaram-se 1, 2, 3, e 5% de lignina kraft, em relação à massa seca da matéria-prima. A adição de lignina kraft em pellets de eucalipto contribuiu para a melhoria das propriedades físicas e mecânicas, no que se diz respeito à densidade, durabilidade mecânica, teor de finos e dureza. Conclui-se que a adição de lignina para produção de pellets é viável tecnicamente, desde que sejam utilizadas ligninas com menores teores de cinzas e umidade. O Artigo III teve como objetivo avaliar as propriedades de pellets de bagaço de cana-de-açúcar torrificados. As temperaturas utilizadas na torrefação dos pellets foram de 180, 210, 240, 270 e 290°C, por 15 minutos, em atmosfera com quantidade limitada de oxigênio. A torrefação resultou em pellets com menores densidades aparente e a granel, além de menor durabilidade mecânica, menor dureza e maior percentagem de finos, porém os valores médios são compatíveis com as exigências das normas europeias de comercialização. Devido à perda de oxigênio e hidrogênio e aumento no teor de carbono dos pellets torrificados a partir da temperatura de 240 oC, observou-se aumento no poder calorífico superior. Os maiores valores de densidades energéticas foram observados nos pellets torrificados nas temperaturas de 180, 210 e 270oC, em média, 12,6% maior que a testemunha. Dentre as temperaturas de torrefação avaliadas neste estudo, os pellets torrificados em 270°C foram os que apresentaram o melhor potencial. De modo geral, concluiu-se que a produção de pellets é tecnicamente viável, com diversas biomassas encontradas no Brasil. A adição de lignina kraft e/ou torrefação podem ser alternativas para melhoria das propriedades dos pellets, além da adequação às normas de comercialização europeias. / The development of pellets production in Brazil is promising due to the increasing global consumption of pellets. However, there are few studies on pelletizing in the country. Article I aimed to evaluate properties of raw material and pellets produced with different Brazilian biomass. There were used forest biomass (wood, bark and branch of eucalyptus and pine wood) and agricultural biomass (cotton waste, sugar cane bagasse, elephant grass and rice straw). Physical, mechanical and chemical properties of different biomass and pellets were determined. The pellets were classified according to European marketing standards. Among the forest biomass, the pine wood pellets stood out compared to the others due to the higher net calorific value and lower ash content. Among the agricultural biomass, sugar cane bagasse presented the most favorable properties for pellets production. Article II aimed to evaluate the influence of the kraft lignin addition in Eucalyptus pellets properties. The raw material used was wood with bark of a Eucalyptus grandis x Eucalyptus urophylla clone, and 10% eucalyptus harvest waste. Besides the control (0% lignin), there were added 1, 2, 3, and 5% kraft lignin on a dry mass of raw material. The addition of kraft lignin contributed to improving the physical and mechanical pellets properties, as regards the bulk density, mechanical durability, hardness and fines content. We conclude that the addition of lignin pellets for production is technically feasible, provided they are used lignins with lower ash content and moisture. Article III aimed to evaluate the properties of torrefied sugar cane bagasse pellets. The temperatures used in the pellets torrefaction were 180, 210, 240, 270 and 290°C for 15 minutes. Torrefaction resulted in pellets with lower density, lower mechanical durability, lower hardness and a higher percentage of fines, but the average values are compatible with the requirements of European marketing standards. Due to loss of oxygen and hydrogen and increase the carbon content of the torrefied pellets, there was an increase in the gross calorific value from the torrefaction temperature of 240°C. Higher energy densities were observed in torrefied pellets at temperatures of 180, 210 and 270°C, on average, 12.6% higher than the control. Among the torrefaction temperatures evaluated in this study, the torrefied pellets in 270°C showed the best potential. In general, it was found that the production of pellets is technically feasible with biomass found in Brazil. The addition of kraft lignin and / or torrefaction can be alternatives for improving the properties of pellets, as well as compliance to European marketing standards. / Não foi encontrado o cpf do autor e nem o termo de autorização.

O objetivo deste trabalho foi desenvolver formulações de pellets contendo teofilina, utilizando a goma gelana como aglutinante. Inicialmente, o uso desse polímero foi avaliado em comparação com o PVP. Por meio de delineamento experimental 32 foram analisadas as variáveis aglutinante e diluente. Os pellets obtidos apresentaram resultados satisfatórios na friabilidade e esfericidade. Verificou-se que o diluente exerceu influência significativa na granulometria, de modo que formulações com manitol apresentaram maior formação de pó após a produção. Com relação ao aglutinante sua maior influência foi na dissolução, pois formulações com gelana apresentaram eficiência de dissolução, em média, menor que as formulações com PVP. A seguir, foi avaliada a influência do polímero, sua quantidade, e seu modo de incorporação nas formulações. Para isso foi realizado um delineamento experimental 23, tendo a gelana, a quantidade, e a incorporação como variáveis. Verificou-se que a característica que sofreu maior influência das variáveis foi a granumoletria, pois as condições empregadas influenciaram significativamente o rendimento de pellets. Com relação à friabilidade, esfericidade e dissolução, não foram observadas diferenças significativas entre os resultados, ainda que algumas tendências puderam ser identificadas. / Aim of this work was to develop pellet formulations containing theophylline, using gellan gum as a binding agent. Inicially, application of the polymer was compared with PVP. By a 32 experimental design, variables binder and diluent were analyzed. Pellets presented satisfactory results in friability and sphericity. It was found that the diluent exerted significant influence on granulometry, so formulations with mannitol showed higher dust formation after production. Regarding binder variable, its higher influence was in the dissolution, since formulations with gellan presented smaller dissolution efficiency than formulations with PVP. Next, the influence of polymer, amount, and incorporation were evaluated. In this part, a 23 experimental design was carried out, with gellan, quantity, and incorporation as variables. It was found that granulometry was the most influenced by variables. So conditions employed influenced significantly the yield of pellets. Regarding friability, sphericity and dissolution, no significant differences were observed, although some trends could be identified.

No description available.

Pelletsuppvärmning konkurrerar idag med fjärrvärme och värmepumpar. Det är därför viktigt att reducera de problem som kan uppstå vid användandet av pellets. Ett vanligt problem som kan uppstå är söndersmulad pellets som kan sätta igen pelletspannan. När pelletsen smulas sönder innebär det att pelletsen har en för låg hållfasthet. Målet med arbetet är att analysera pellets med olika kvalitéer gällande hållfasthet, fukthalt, bulkdensitet samt enskild densitet. Även undersöka om enskild densitet för pellets har ett samband med dess hållfasthet. Enskild densitet kommer analyseras med två olika analysmetoder ”fila och mäta”-metoden och ”doppa pellets” i trögflytande vätska-metoden. Målet är vidare att eventuellt vidareutveckla metoden ”doppa pellets”. Resultaten för metoden ”fila och mäta” visar ett samband mellan pelletsens enskilda densitet och hållfasthet. Där visas en tendens att med ökad enskild pelletsdensitet ökar hållfastheten. Däremot visar inte resultaten för metoden ”doppa pellets” något samband mellan pelletsens enskilda densitet och hållfasthet. Metodutveckling av ”doppa pellets” visade inga framsteg.