Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xi, 100 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 83-86).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xiii, 104 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).

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Orientador: Sandra Cristina dos Santos Rocha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-14T18:51:32Z (GMT). No. of bitstreams: 1 Cunha_RobertoLuisGomesda_D.pdf: 5308810 bytes, checksum: 23031bb71d61ff09f951cb9f06de28e9 (MD5) Previous issue date: 2009 / Resumo: Atualmente a granulação de partículas finas encontra suas principais aplicações nas indústrias de alimentos, química, agrícola e especialmente farmacêutica e tem sido cada vez mais objeto de pesquisa, com finalidades de melhorar aspecto, perdas por manuseio, compactação e transporte. A granulação consiste em aumentar o tamanho (volume) da partícula, através da incorporação de materiais ativos e/ou inertes. Os primeiros trabalhos foram desenvolvidos na década de 50, utilizando areia em granuladores cilíndricos. Desde então, uma grande quantidade de trabalhos vem sendo realizado com a utilização de equipamentos tais como misturadores, tambores rotativos e leito fluidizado. A utilização do leito fluidizado modificado tem como objetivo melhorar o processo, otimizando a técnica e tornando-a economicamente viável. Neste trabalho, estudou-se a granulação de pós em leito fluidizado com tubo interno, utilizando uma solução aquosa com concentração de 35 % de maltodextrina como agente granulante, e efetuou-se a caracterização física dos grânulos formados e de pastilhas obtidas a partir desses grânulos. O material empregado como excipiente foi a celulose microcristalina com diâmetros que variam de partículas menores que 125 mm a 420 mm. O leito consiste de uma coluna em acrílico de 60 cm de altura e 14 cm de diâmetro interno. Um tubo com 14 cm de altura e 7 cm de diâmetro interno foi adaptado no centro do leito, preso ao topo por uma haste retrátil, facilitando o seu deslocamento e fixação em relação à placa distribuidora. A utilização do leito fluidizado com um tubo interno facilitou a condução do processo em relação ao leito fluidizado convencional, pois foi observada uma melhora na fluidodinâmica durante o processo. A solução granulante foi aspergida sobre o leito de partículas, através de um bico atomizador de duplo-fluido. As variáveis operacionais analisadas foram: vazão da solução granulante (Ws), com valores de 4, 7 e 10 ml/min no display da bomba, pressão de atomização (Pat) de 68,95, 103,42 e 137,89 kPa, temperatura do ar de fluidização (T) de 60, 70 e 80 °C, e altura do tubo interno (ht) em relação à placa distribuidora de 4, 6 e 8 cm. O trabalho experimental foi realizado com auxílio de um planejamento fatorial completo 24 para avaliar a influência das condições operacionais nas variáveis de resposta: crescimento das partículas, índice de torrões e índice de Carr. O planejamento experimental forneceu modelos estatisticamente significativos para as respostas crescimento dos grânulos e índice de Carr. O crescimento dos grânulos foi favorecido pelo aumento da vazão da solução granulante associada à baixa pressão de atomização. Os grânulos apresentaram compressibilidade de 2,44 a 16,9 % e ângulo de repouso de 37,6±1,77° a 42±1,49°, indicando ótima fluidez e coesividade intermediária. Além disso, analisou-se também a compressão e compactação dos grânulos. Pastilhas foram confeccionadas aplicando 1,5 ton. aos grânulos em prensa hidráulica e submetidas à análise de resistência. Os resultados mostraram-se satisfatórios, estando os valores obtidos de acordo com os especificados na literatura. / Abstract: Currently the fine particle granulation finds its main applications in the food chemical, agricultural and especially pharmaceutical industries, and has been attracting more and more interest with purposes to improve aspect, losses, compacting and transport. The granulation consists of increasing the size of the particle, through the incorporation of active and/or inert materials. The first works had been developed in the decade of 50. Since then, a great amount of works comes, being carried through with the use of different equipments such as mixers, rotary drums and fluidized beds. Modified fluidized bed granulators had been proposed with the objective of improving the process. The use of modified fluidized beds optimizes the technique and turns it economically viable. The objective of this work was the study of granulation of powders in a fluidized bed modified with the inclusion of a draft-tube, using an aqueous solution of maltodextrin (35% in weight), and the physical characterization of the granules and tablets compressed from these granules. The granulation operation was carried out by top spraying the granulating liquid on the fluidized bed of particles using a double-fluid nozzle. Microcrystalline cellulose particles (mean diameter from below 125µm to 420µm) were chosen as the raw material to be granulated. The fluidized bed consisted of a cylindrical column constructed in Plexiglass with 0.14 m of internal diameter and 0.6 m of height. A draft-tube with 0.14 m of height and 0.07 m of internal diameter was adapted in the center. The experimental work was carried through with the aid of a 24 experimental design with three central points, resulting in 19 runs to evaluate the effects of the operational variables on the granulation process. The independent variables studied were the flow rate of granulating solution (Ws); the air pressure of atomization (Pat); the inlet air temperature (T) and the height of the drafttube (ht). The values of the variables at the lower, central and upper levels were fixed in 4, 7 and 10 mL/min for Ws; 68.95, 103.42 and 137.89 kPa for Pat; 60, 70 and 80°C for T and 4, 6 and 8 cm for ht. The responses analyzed were the particles growth, agglomeration index, angle of repose and Carr index. The growth of granules was favored by the increase of the flow rate of the granulating solution associated to a low pressure of atomization. The granules showed compressibility in the range of 2.44 to 16.9% and angle of repose from 37.6±1.8° to 42.0±1.5°, indicating free flow ability and intermediate cohesiveness. Also, the granules compression and compaction was analyzed. Tablets were done by applying 1.5 tons to the granules using a hydraulic press and then submitted to resistance analyses. The results obtained were satisfactory as the values were in the range specified in the literature for pharmaceutical tablets. / Doutorado / Engenharia de Processos / Doutor em Engenharia Química

Of the many thermochemical conversion pathways for utilizing biomass as a renewable energy source, fast pyrolysis is a promising method for converting and upgrading carbonaceous feedstocks into a range of liquid fuels for use in heat, electricity and transportation applications. Experimental trials have been carried out to assess the impact of operational parameters on process yields. However, dealing with larger-scale experimental systems comes at the expense of lengthy and resource-intensive experiments. Luckily, the advances in computing technology and numerical algorithm solvers have allowed reactor modelling to be an attractive opportunity for reactor design, optimization and experimental data interpretation in a cost-effective fashion. In this work, a fluidized bed reactor model for biomass fast pyrolysis was developed and applied to the Bell’s Corners Complex (BCC) fluidized bed fast pyrolysis unit located at NRCan CanmetENERGY (Ottawa, Canada) for testing and validation. The model was programmed using the Microsoft Visual Basic for Applications software with the motivation of facilitating use and accessibility as well as minimizing runtime and input requirements. The application of different biomass devolatilization schemes within the model was conducted, not only for biomass fast pyrolysis product quantity but also liquid product composition (quality), to examine the effect of variable reaction kinetic sub-models on product yields. The model predictions were in good agreement with the results generated from the experimental work and mechanism modifications were proposed which further increased the accuracy of model predictions. Successively, the formulation of the modelled fluid dynamic scheme was adapted to study the effect of variable hydrodynamic sub-models on product yields for which no significant effect was observed. The work also looked into effect of the dominant process variables such as feedstock composition, bed temperature, fluidizing velocity and feedstock size on measurable product outputs (bio-oil, gas and biochar) and compared the results to those generated from the experimental fast pyrolysis unit. The ideal parameters for maximizing bio-oil yield have been determined to be those which: minimize the content of lignin and inorganic minerals in the feedstock, maintain the dense-bed temperature in a temperature range of 450-520 ºC, maximize the fluidization velocity without leading to bed entrainment, and limit the feedstock particle size to a maximum of 2000 μm.

Gasification is a promising technique for transforming solid biomass into a gas that can be used to produce renewable heat, power, fuels or chemicals. Biomass materials, such as forestry residues, can be high moisture, heterogeneous mixtures with low bulk density - properties that make them difficult to handle and convert. Consequently, this means that feedstock pre-treatment is usually necessary in order to facilitate its conversion by gasification. Pre-treatments methods, which include comminution, drying, pelletization, torrefaction, or carbonization will affect the properties of the biomass which will affect their gasification in a fluidized bed. The objective of this thesis was to determine how biomass pre-treatment can influence gasification in a fluidized bed. A single forestry residue was processed using five pre-treatment process levels: sieving (as a surrogate for comminution), drying (moisture content), pelletization, torrefaction, and carbonization. The fractions derived from these processes were gasified in a small pilot-scale air blown bubbling fluidized bed gasifier (feed rate 8 – 25 kg/h). The particle size and form had an impact on the gas composition, tar content, and cold gas efficiency of the gasification. Over the conditions tested, the finest fraction produced a gas with a H2/CO ratio of 0.36 – 0.47 containing 7 – 59 g/m3 tar (gravimetric) at a cold gas efficiency of 30 - 41%. The pellets on the other hand yielded a gas with a H2/CO ratio of 0.89 - 1.14, containing 3 – 37 g/m3 tar (gravimetric) at a cold gas efficiency of 41 – 60%. Drying, torrefaction and carbonization also had an impact on the gasification performance. Carbonization was able to reduce the yield of tar (as measured by gas chromatography) by more than 95% relative to the parent material. Finally, four different forestry residues were gasified in a large pilot-scale bubbling fluidized bed with air and steam-oxygen mixtures (feed rate 200 – 245 kg/h) in order to assess whether the comminution effect could be observed at the large scale. One feedstock with a significant portion of small particles showed the expected effects compared to the feed materials with large feed particles: lower H2/CO ratio, greater tar yield, lower cold gas efficiency while the other feed material containing a substantial amount of small particles did not show these effects.

Fluidization of biomass particles is an important process in the gasification, pyrolysis and combustion in order to extract energy from biomass. Studies on the fluidization of biomass particles (corn cob and walnut shell), inert particles (sand, glass bead, and alumina), which are added to facilitate fluidization of biomass, and biomass/sand mixture were performed. Experiments were carried out in a 14.5 cm internal diameter cold flow fluidization bed to determine minimum fluidization velocities with air as fluidizing medium. On the of basis of experimental data from both present work and those found in the literature, new correlations were developed to predict minimum fluidization velocity for inert particles as well as biomass particles. It was found that the proposed correlations satisfactorily predict minimum fluidization velocities and was in well agreement with experimental data. Furthermore, effect of weight percentage of biomass in the biomass/sand mixtures was studied. The weight fraction of biomass particles in the mixture was chosen in the range of 0 ~ 100 wt. %. The results show that minimum fluidization velocity of the mixtures increases with an increase in biomass content. Using the present experimental data, a new correlation was developed in terms of mass ratio for predicting values of minimum fluidization velocity of these mixtures. However, the validity of the proposed correlation should be further studied by conducting more experiments using the biomass/sand mixtures of different particle size, shape, and density.

No description available.

Nitrification performance of three, fluidized-bed filters was investigated. Each filter contained 10 L of plastic bead medium (near neutral specific gravity and 2-4 mm diameter and length) and was loaded under conditions of various flow rates and ammonia levels. Bead settled depth and biofilter diameter (12.7, 15.2 and 17.8 cm) were the factors differing among the filters. The experiments were conducted with three replicate recirculating systems. Each system included one of the three different biofilter types, connected in parallel to a reservoir containing 500 L of water. Systems were allowed to acclimate using a synthetic nutrient substrate, which was followed by a comparative analysis of biofilter performance. To evaluate filter performance, ammonia inflow concentration, ammonia loading rates, nitrite, nitrate, temperature, pH, dissolved oxygen levels, hardness, alkalinity and flow rates were monitored. Initially, four different flow rates, ranging from 6 Lpm–12 Lpm, were tested at constant ammonia feed level (8.4 g/day). Here, biofilter D3 (17.8 cm diameter) showed the best ammonia removal performance at a flow rate of 6 Lpm, followed by the performance of D1 (12.7 Lpm) and D2 (15.2 Lpm). The difference in ammonia and nitrite removal performance decreased among the biofilters, as flow rate increased. An increase in flow rate also lowered ammonia level in the systems at a constant ammonia loading, but did not affect the nitrite concentration. Five different ammonia feed rates, ranging from 8.4 – 16.8 g/day, were tested in the second part of the study, at a constant flow rate of 12 Lpm in each column. Different ammonia and nitrite removal performance was observed between biofilter sizes. Ammonia accumulated in the tanks as ammonia loading increased, but nitrite concentration remained relatively constant. The results indicated that nitrification performance improved by 17 % as the applied flow rate was increased. Ammonia concentration decreased slightly, from 0.6 mg/L to 0.5 mg/L. The performance appeared to be limited at higher ammonia loadings, at which time ammonia concentration increased from 0.5 to 0.99 mg/L. Data on biofilm development indicates a reduction in biofilm thickness as flow rate was increase, and significant biofilm accumulation as ammonia supply increased. The results of this work were compared to performance data generated using a steady state biofilm model, developed by Rittmann and McCarty (1980). The model predicted higher values of biofilm thickness (Lf) than those seen in this study. Fluidized bed filters with plastic bead medium proved to be effective in removing ammonia and nitrite from a synthetic aquaculture water. / Master of Science