Ce travail a pour objectif d'améliorer la prédictivité des modèles à deux fluides pour la description des lits fluidisés gaz-solide pour les particules du groupe A dans la classification de Geldart. La première partie traite de l'incorporation de nouveaux phénomènes physiques dans le formalisme statistique utilisé : collisions induites par le cisaillement, phénomènes de lubrification lors des chocs et forces inter-particulaires. La deuxième partie traite de la résolution numérique du modèle. Il est montré que la simulation des lits de particules de type A présente une très forte sensibilité au maillage, conduisant à une surestimation de la hauteur du lit. L'introduction du formalisme filtré permet d'identifier la traînée filtrée comme étant l'origine principale du problème. Deux modèles de sous-maille sont proposés pour la prédiction de celle-ci et sont testés à la fois sur une configuration académique et sur une expérience de laboratoire. / This work aims to increase the predictivity of the two-fluid model in gas-solid fluidized beds of Geldart A particles. The first part deals with the integration of physical phenomena into the two-fluid model: shear-induced collisions, lubrication between particles and inter-particular forces. The second part deals with the practical resolution of the two-fluid model using numerical codes. It is shown that bed expansion for Geldart A particles have a strong dependance on the mesh size used to compute the flow, leading to a major overestimation. The filtered approach is used and points up the filtered drag as the key of the problem. Two subgrid drag models are proposed and tested on both academic and laboratory configurations.

In this thesis, a thorough study of the batch top-spray fluidized bed granulation was carried out including experimental study, population balance model (PBM), computational fluid dynamic (CFD) study and control strategy development. For the experimental study, the influence variables of pulsed frequency, binder spray rate and atomization pressure of a batch top-spray fluidized bed granulation process were studied using the Box-Behnken experimental design method. Different mathematical models were developed to predict the mean size of granules, yield, relative width of granule distribution, Hausner ratio and final granule moisture content. Validation experiments have shown the reliability and effectiveness of using the Box-Behnken experimental design method to study a fluidized bed granulation process. The one-dimensional population balance models (ODPBMs) have been developed to model a pulsed top-spray fluidized bed granulation, linking the operating factors of the pulsed frequency, the binder spray rate, and atomization air pressure with the granule properties to predict granule growth behavior at different operating conditions. A multi-stage open optimal control strategy based on the developed ODPBMs was proposed to reduce the model and process mismatch through adjusting the trajectory of the evolution of the granule size distribution at predefined sample intervals. The effectiveness of the proposed modeling and multi-stage open optimal control strategy has been validated by experimental and simulation tests. In addition, an Eulerian-Eulerian two-fluid model (EETFM) was developed to describe the gas-particle two-phase flow in the fluidized bed granulator. By computational fluid dynamic analysis, it has been proven that the fluidized bed granulation system is not homogeneous, based on which a two-compartmental population balance model (TCPBM) was developed to describe the particle growth in the fluidized bed granulation. Validation experiments have shown the effectiveness and superior accuracy of the TCPBM comparing with the ODPBM in predicting the final particle size distribution.

A mild gasification method has been developed to provide an innovative clean coal technology. The objective of this study is to developed a numerical model to investigate the thermal-flow and gasification process inside a specially designed fluidized-bed mild gasifier using the commercial CFD solver ANSYS/FLUENT. Eulerain-Eulerian method is employed to calculate both the primary phase (air) and secondary phase (coal particles). The Navier-Stokes equations and seven species transport equations are solved with three heterogeneous (gas-solid), two homogeneous (gas-gas) global gasification reactions. Development of the model starts from simulating single-phase turbulent flow and heat transfer to understand the thermal-flow behavior followed by five global gasification reactions, progressively with adding one equation at a time. Finally, the particles are introduced with heterogeneous reactions. The simulation model has been successfully developed. The results are reasonable but require future experimental data for verification.

Objetivou-se neste trabalho avaliar a influência do tempo de detenção hidráulica (TDH) na remoção do surfactante aniônico, alquilbenzeno linear sulfonado (LAS), de água residuária de lavanderia, em dois reatores de leito fluidificado (RLF) operados em TDH de 8 horas (RLF1) e 12 horas (RLF2). Os reatores foram inoculados com biomassa de lodos ativados e foi investigado a influência da adição de nitrato e etanol na degradação do LAS e seus impactos na comunidade microbiana. Para tal fim, o trabalho foi desenvolvido nas fases que se seguem: caracterização da água residuária de lavanderia comercial, ensaio de degradação desnitrificante de LAS, operação dos reatores de leito fluidificado, planejamento experimental de condições ótimas de degradação de surfactante em reatores em batelada e caracterização microbiana do consórcio microbiano do RLF1 e RLF2 por meio do Illumina MiSeq. Verificou-se considerável remoção de LAS (77%) no ensaio de degradação sob condição desnitrificante nos reatores em batelada com 21 mgLAS/L e adição de 100 mgNO3-/L. Ao longo de 436 dias de operação, verificou-se elevada remoção de LAS em RLF1 e RLF2, todavia, observou-se diferença significativa; ou seja, maior remoção global de LAS (99±3%) para 22,5±5,9 mg /L afluente em RLF2. A adição de etanol influenciou, notadamente, a remoção de LAS em RLF1, por outro lado a adição de nitrato exerceu influência na remoção de LAS em ambos os reatores. Na realização do planejamento experimental, em reatores em batelada, pode-se obter condições ótimas de degradação de LAS, verificando-se os valores críticos para etanol de 97,5 mg /L, e de 87,5 mg /L para nitrato. Para as seis etapas de operação foram identificados gêneros relacionados à desnitrificação e a degradação de LAS. Para Etapa I, foram identificadas bactérias relacionadas com a redução de nitrato, dentre eles Flavobacterium, Sphingobium e Xanthobacter. Para as etapas com adição de surfactante (II, III, IV, V e VI) identificou-se Dechloromonas, Zoogloea, Novosphingobium, Pseudomonas, Acinetobacter e Desulfobulbus, provavelmente relacionadas à degradação de LAS. / The aim of this study was to evaluate the influence of hydraulic retention time (HRT ) on anionic surfactant; linear alkyl benzene sulphonate (LAS) from laundry wastewater in two fluidized bed reactors (FBR) operated in HRT of 8 hours (FBR1) and 12 hours (FBR2). The reactors were inoculated with activated sludge and the influence of nitrate and ethanol addition on LAS removal was studied with subsequent impact on microbial diversity. The study was conducted in following phases; laundry wastewater characterization, denitrifying degradation potential of LAS, fluidized bed reactor operation under specified conditions, central composite design, and determination of microbial shift between biofilm of FBR1 and FBR2 through Mi-Seq Illumima®. Higher LAS removal (77%) was verified in denitrifying potential degrading of LAS using batch reactors feed with 21 mg LAS /L and 150mg NO3-/L. Great LAS removal efficiency was observed for 436 days, however significant notice was observed for global LAS removal between FBR1 and FBR2, i.e. greater LAS removal in FBR2 (99±3% for 22,5 ±5,9 mg LAS/L) than FBR1 (93 ±12% for 20,6 ±4,4 mg LAS /L). The ethanol addition significantly influenced FBR1 efficiency while nitrate addition improves LAS removal in both reactors. Central composite design resulted into optimal values for LAS removal (94%) in addition to 97,5 mg/L ethanol and 87,5 mg/L nitrate. Microbial shift showed genus abundance related to denitrification and LAS degradation. In Step I denitrifying bacteria Flavobacterium, Shingobium and Xanthobacter were identified. For Steps with laundry wastewater addition, Dechloromonas, Zoogloea, Novosphingobium, Pseudomonas, Acinetobacter and Desulfobulbus, were identified, probably, related to LAS degradation.

O estado de São Paulo produz cerca de 58.700 t/dia de resíduos dividido pelos seus 645 municípios nas vizinhanças de aproximadamente 170 usinas de açúcar e álcool. Diante deste fato, é evidente o potencial para se fazer o uso consorciado destes dois combustíveis na geração de energia. Este trabalho investigou os possíveis efeitos deletérios que a presença de cloro, flúor, sódio e potássio possam trazer nas caldeiras voltadas para a produção de energia elétrica, utilizando bagaço de cana e combustível derivado de resíduo (CDR). Foi realizada uma busca criteriosa na literatura internacional a fim de possíveis efeitos deletérios em caldeiras de biomassa para a produção de energia em razão do uso consorciado de resíduo, no aspecto da integridade da caldeira, principalmente no papel desempenhado pelos elementos, cloro, flúor, sódio e potássio, e em seguida uma análise criteriosa dos resultados encontrados. Esta análise foi realizada através de um estudo de caso, considerando uma caldeira de leito fluidizado borbulhante (BFB) de 60MW, queimando bagaço e parte do resíduo de uma cidade de 600.000 habitantes. Verificou-se que o resíduo que a cidade produz pode ser transformado em CDR que irá alimentar a caldeira como combustível auxiliar, produzindo energia elétrica de forma limpa e sustentável. Um parâmetro utilizado para se definir a quantidade máxima de CDR queimada na caldeira, foi o cloro específico, calculado pela razão entre o teor de cloro e o poder calorífico inferior (PCI) do combustível. Com base na literatura encontrada, limitou-se o cloro específico em 40 mg/MJ, para que não haja danos a integridade do equipamento. A combustão consorciada de bagaço de cana e CDR pode ser uma alternativa para o estado de São Paulo reduzir o problema da falta de aterros para descarte de resíduos e uma possibilidade para as usinas de açúcar e álcool produzirem energia elétrica por um período mais extenso no ano, economizando bagaço de cana. / The state of São Paulo produces about 58,700 tons/day waste divided by its 645 municipalities in the vicinity of about 170 sugar and alcohol mills. Given this fact, the potential is evident to make the consortium use of these two fuels in power generation. This paper investigated the potential deleterious effects that the presence of chlorine, fluoride, sodium and potassium can bring the boilers focused on the production of electric power using bagasse and refuse derived fuel (RDF). A thorough search in the international literature with the view to possible deleterious effects on biomass boilers for power generation because of consortium use of residue in the boiler integrity aspect, particularly the role played by the elements chlorine, fluorine, sodium and potassium, and then a careful analysis of the results. This analysis was conducted through a case study, considering a bubbling fluidized bed (BFB) boiler of 60 MW, burning bagasse and part of the residue of a city of 600,000 inhabitants. It was found that the residue that the city produces can be turned into RDF which will feed the boiler as an auxiliary fuel, producing electricity in a clean and sustainable manner. A parameter used to set the maximum amount of burned RDF in the boiler, was the specific chlorine, measured by the ratio between the chlorine content and the lower heating value (LHV) of the fuel. Based on the literature found, the specific chlorine was limited to 40 mg/MJ, so there is no damage to the integrity of the equipment. The consortium combustion of bagasse and RDF can be an alternative to the state of São Paulo reduce the problem of landfills for waste disposal and a possibility for the sugar and alcohol mills producing electric power for a longer period in the year, saving bagasse.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-07-06T16:41:24Z No. of bitstreams: 1 Flavio Michels Bianchi_.pdf: 5656297 bytes, checksum: babcb37759c827b4912894a5e8a91ccd (MD5) / Made available in DSpace on 2018-07-06T16:41:24Z (GMT). No. of bitstreams: 1 Flavio Michels Bianchi_.pdf: 5656297 bytes, checksum: babcb37759c827b4912894a5e8a91ccd (MD5) Previous issue date: 2018-03-21 / Nenhuma / Baseado na tecnologia de leito fluidizado borbulhante, um combustor em escala de bancada foi utilizado para conduzir trabalho de pesquisa em coqueima de misturas de carvão mineral e biomassa (serragem). O carvão mineral presente no sul do Brasil é na sua maioria do tipo sub-betuminoso e é beneficiado para alcançar requisitos típicos das usinas termelétricas localizadas no sul do Brasil. Tem aproximadamente 40% de cinzas e uma substancial quantidade de enxofre (aproximadamente 2%). A umidade é um componente comum nas biomassas e que pode dificultar a combustão da biomassa pura exigindo ajustes operacionais. Além disso, o percentual de umidade normalmente sugere poderes caloríficos menores quando comparados com o carvão. Verificando algumas características destes combustíveis a queima combinada aparece como possibilidade de minimizar problemas associados a queima singular destes combustíveis. A proposta deste trabalho foi de determinar a melhor proporção de mistura para a operação de coqueima, misturando carvão mineral e biomassa de madeira em um combustor de leito fluidizado borbulhante em escala de bancada. Resultados experimentais sugerem que misturas de combustível contendo até 10% de biomassa oferecem melhores resultados em termos de emissões e controle da estabilidade das temperaturas. Também foi pretendido avaliar o impacto das emissões nos gases de exaustão quando comparado com a queima simples de carvão mineral em leito fluidizado borbulhante. O estudo apresentou boa eficiência de combustão para os casos considerados, incluindo baixas emissões de CO e alcatrões. As emissões de SO2 não foram afetadas pela presença da biomassa. Ademais, o regime de fluidização de 6 umf e o excesso de ar de 70% foram estimados como mais assertivos para a operação baseados no desempenho e temperatura dos gases de exaustão. / Based on bubbling fluidized bed technology, a bench scale combustor was used to conduct research works in co-firing of coal and biomass (wood shavings) blends. South Brazilian subbituminous coal, beneficiated to achieve typical thermal power plant requirements located in south Brazil. Still have about 40% of ash content and a substantial amount of sulfur (around 2%). Related to some processes including an environmentally friendly concept of combustion, but not giving up the reliability of coal in terms of supply and storage, a co-firing of coal together with biomass agrees with these interests. Biomass wood shavings in the south of Brazil are cheap, easy to find and an obviously renewable source of energetic fuel. Nevertheless, this kind of biomass is rich in moisture. The moisture is a usual component of biomasses, which may hinders the combustion of biomass alone requiring operational adjustments. Furthermore, the percentage of moisture normally suggests lower heating values when compared to coal. Characteristics of these fuels indicate that cofiring can minimize problems associated with the single burning of these fuels. The purpose of this work was to determine the best blend proportion of operation for co-firing, mixing coal and wood shavings in a bubbling fluidized bed bench scale combustor. Experimental results suggest that fuel blends containing up to 10% biomass provide better results in terms of emissions and temperature control. It was also intended to evaluate the impact on flue gas emissions when compared with just coal burning in a bubbling fluidized bed. The study presented good combustion efficiency for the considered cases, including low emissions of CO and tars. SO2 emissions were not affected by the presence of biomass. In addition, the fluidization regime of 6 umf and the excess air of 70% were estimated as more assertive for the operation based on the performance and temperature of the exhaust gases.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-11-04T14:53:35Z No. of bitstreams: 1 Helmuth Reguly Junior_.pdf: 1561804 bytes, checksum: b11f0f561f69a1560738aa1ccb8f4118 (MD5) / Made available in DSpace on 2015-11-04T14:53:35Z (GMT). No. of bitstreams: 1 Helmuth Reguly Junior_.pdf: 1561804 bytes, checksum: b11f0f561f69a1560738aa1ccb8f4118 (MD5) Previous issue date: 2015-06-24 / UNISINOS - Universidade do Vale do Rio dos Sinos / No presente trabalho, foram feitas análises espectrais de sinais de flutuação de pressão obtidos de simulações computacionais de leitos fluidizados. As simulações foram realizadas com o aplicativo ANSYS FLUENT 14.0. O modelo multifásico empregado foi o modelo de dois fluidos (TFM) Euler-granular. As tensões das fases sólidas foram modeladas pela Teoria Cinética dos Escoamentos Granulares (KTGF). Foram simulados dois leitos, um leito bidimensional em regime de fluidização rápida e um leito tridimensional em regimes borbulhante e turbulento, ambos com partículas do grupo B de Geldart. Os sinais de flutuação de pressão gerados nas simulações numéricas foram analisados via densidade espectral de potência. Foram identificados o mínimo período de tempo de simulação para gerar sinais estatisticamente significativos, bem como a mínima frequência de aquisição necessária para o tratamento dos sinais, os quais foram iguais a 32,5 s e 250 Hz, respectivamente. No leito 3D, o regime borbulhante foi caracterizado por picos nas frequências de 1,5 e 2,2 Hz, enquanto o regime de fluidização rápida simulado em 2D foi caracterizado por um pico a uma frequência de 0,12 Hz, o que se acredita estar relacionado com a frequência de movimento dos aglomerados de partículas. Também foi possível verificar a diferença entre os espectros de potência dos regimes borbulhante e turbulento, que são diferenciados pelos picos de frequência. No regime borbulhante foram identificados dois picos de frequência, enquanto no regime turbulento foi identificado apenas um pico. / In this study, spectral analyses of pressure fluctuation signals obtained from computational simulations of fluidized beds were done. The simulations were performed using ANSYS FLUENT 14.0. The multiphase model employed was the Euler-granular two-fluid model (TFM). The solid stresses were modeled by the kinetic theory of granular flows (KTGF). Two beds were simulated, a two-dimensional bed in fast fluidization regime and a three-dimensional bed in bubbling and turbulent regimes, both with Geldart-B particles. The pressure fluctuation signals generated by numerical simulations were analyzed via power spectral density. The minimum simulation periods to generate statistically significant signals were identified, as well as the minimum sampling rate required for the processing of signals, which were found equal to 325 and 250 Hz, respectively. In the 3D bed, the bubbling system was characterized by peaks at frequencies of 1.5 and 2.2 Hz, while the fast fluidization regime simulated in 2D was characterized by a peak at a frequency of 0.12 Hz, which may be related to the rate of motion of clusters. A major difference between the power spectra of bubbling and turbulent regimes was observed. In the bubbling regime, two frequency peaks may be identified, while in turbulent regime only one frequency peak appears.

No Brasil a esquistossomose é causada pela espécie Schistosoma mansoni e leva principalmente à formação de granulomas e fibroses, hipertensão portal e hepatoesplenomegalia. O praziquantel (PZQ) é o fármaco de primeira escolha para o tratamento e possui baixa solubilidade aquosa, sendo necessárias altas doses para ação terapêutica. A taxa de dissolução do PZQ é fator limitante para a sua biodisponibilidade, portanto, melhorar sua solubilidade é fundamental. O objetivo deste trabalho foi aumentar a solubilidade do PZQ pela obtenção de grânulos contendo dispersões sólidas deste fármaco pelo processo hot melt em leito fluidizado. Além disto, buscou-se estudar a fluidodinâmica e as variáveis do processo de granulação. Inicialmente, dispersões sólidas foram preparadas por simples fusão em polietilenoglicol (PEG) 4000 e PEG 6000 nas proporções 2:1; 1:1; 1:2; 1:5 e 1:10 e estas foram caracterizadas por teste de solubilidade, difração de raios-X, espectroscopia em infravermelho e análises térmicas (DSC e TG). Foram obtidas dispersões sólidas com uma solubilidade duas vezes maior do PZQ, uma menor cristalinidade, uma possível interação fármaco-carreador e sem degradação ou alteração nos principais grupos funcionais. Com estes resultados, a dispersão sólida 1:10 PZQ:PEG 6000 foi escolhida para a etapa da granulação. Os granulados foram obtidos utilizando o planejamento fatorial Box Behnken com as seguintes variáveis: % de dispersão sólida, proporção PZQ:PEG das dispersões e carga de lactose spray-dried (SD) (g). A caracterização dos grânulos foi realizada pelos testes: granulometria, densidade aparente, densidade compactada, fator de Hausner, índice de Carr, ângulo de repouso e doseamento do fármaco, sendo todas estas propriedades avaliadas pela técnica de superfície de resposta (ANOVA). A análise estatística demonstrou que as características dos granulados são, na maioria dos casos, dependentes da % de dispersão sólida e da proporção de PZQ:PEG, sendo satisfatórios e toleráveis os resultados do fluxo dos granulados. Os três melhores granulados foram escolhidos para as análises de microscopia eletrônica de varredura, espectroscopia em infravermelho, difração de raios-X, análise térmica e perfil de dissolução. Estas análises mostraram que nos grânulos houve diminuição da cristalinidade, possíveis interações entre PZQ, PEG e lactose, além do grande aumento no perfil de dissolução. Com estes resultados, confirmam-se as vantagens da granulação por hot melt em leito fluidizado e a importância do estudo de suas variáveis. / In Brazil, schistossomiasis is mainly attributed to the species Schistosoma mansoni, which causes granulomas and fibrosis, portal hypertension and hepatosplenomegaly. Praziquantel (PZQ) is the first choice in the treatment; however, it has low water solubility, thus requiring high doses for a proper therapeutical result. The PZQ dissolution rate is the limiting factor for its bioavailability; therefore, it is fundamental to improve of this drug solubility. The objective of this work was to increase the PZQ solubility with the production of granules containing its solid dispersions, prepared by hot melt process in fluidized bed. Moreover, the fluid dynamic and several variables of the process were studied. First, solid dispersions were prepared by mixing with melted polyethylene glycol (PEG) 4000 and PEG 6000 at the ratios of 2:1; 1:1; 1:2; 1:5 and 1:10. These were characterized by solubility test, x-ray powder diffraction, fourier transform infrared spectroscopy and thermal analyses (DSC and TG). Solid dispersions were obtained with PZQ solubility two times higher than the pure drug, lower crystallinity and without degradation or alteration in the main functional groups. With these results, the solid dispersion 1:10 PZQ:PEG 6000 was chosen for the studies of granulation. The granulates were obtained using the Box Behnken factorial design with the following independent variables: % of solid dispersion, ratio PZQ:PEG in the dispersions and amount of spray-dried lactose (g). The granules characterization was made by the tests of granulometry, bulk density, tapped density, Hausner ratio, Carr index, angle of repose and PZQ assay. In addition, all these properties were evaluated by response surface technique (ANOVA). The statistical analysis, in most cases, showed that the granules characteristics depend significantly on the % of solid dispersion and on the ratio PZQ:PEG. The results on the granules flow properties are satisfactory and acceptable for tableting. The three granulates with best properties were submitted to scanning electron microscopy, fourier transform infrared spectroscopy, x-ray powder diffraction, thermal analysis and dissolution test. These analyses showed that there were, in the granules, decrease of crystallinity, possible interaction among PZQ, PEG and lactose, and also, greater increase in the dissolution test. The advantages of fluid bed hot melt granulation and the importance of studying the process variables are confirmed by the results in this work.

Bibliography: 208-218.

As part of the production of certain solid-dosage pharmaceuticals, granulated ingredients are dried in a batch fluidized bed dryer. Currently, the determination of the completion of the drying process is accomplished through measurements of product or outlet air temperatures. No quantitative measurement of hydrodynamic behaviour is employed. Changes in bed hydrodynamics caused by variations in fluidization velocity may lead to increased particle attrition. In addition, excessive desiccation of the granules caused by inaccurate determination of the drying endpoint may lead to an increase in the thermal and mechanical stresses within the granules. The activity of future high-potency or peptide based drug products may be influenced by these effects. Therefore, the quantification of hydrodynamic changes may be a key factor in the tighter control of both fluidization velocity and product moisture, which are critical for maintaining product quality. <p>High-frequency measurements of pressure fluctuations in a batch fluidized bed dryer containing pharmaceutical granulate have been used to provide a global, non-intrusive indication of the hydrodynamic changes occurring throughout the drying process. A chaotic attractor comparison statistical test known as the S-statistic, has been applied to quantify these changes in drying and a related unit operation, fluidized bed granulation. The S-statistic showed a sensitivity to moisture which is not seen with frequency and amplitude analysis. In addition, the S-statistic has been shown to be useful in identifying an undesirable bed state associated with the onset of entrainment in a bed instrumented for the collection of both pressure fluctuation and entrainment data. Thus, the use of the S-statistic analysis of pressure fluctuations may be utilized as a low-cost method for determining product moisture or changes hydrodynamic state during fluidized bed drying. <p>Electrical capacitance tomography (ECT) has also been applied in this study to image the flow structure within a batch fluidized bed used for the drying of pharmaceutical granulate. This represents the first time that ECT has been applied to a bed of wet granulate material. This was accomplished through the use of a novel dynamic correction technique which accounts for the significant reduction in electrical permittivity occurring as moisture is lost during the drying process. The correction has been independently verified using x-ray tomography. <p>Investigation of the ECT images taken in the drying bed indicates centralized bubbling behaviour for approximately the first 5 minutes of drying. This behaviour is a result of the high liquid loading of the particles at high moisture. Between moisture contents of 18-wt% and 10-wt%, the tomograms show an annular pattern of bubbling behaviour with a gradual decrease in the cross-sectional area involved in bubbling behaviour. The dynamic analysis of this voidage data with the S-statistic showed that a statistically significant change occurs during this period near the walls of the vessel, while the centre exhibits less variation in dynamic behaviour. The changes identified by the S-statistic analysis of voidage fluctuations near the wall were similar to those seen in the pressure fluctuation measurements. This indicates that the source of the changes identified by both these measurement techniques is a result of the reduction in the fraction of the bed cross-section involved in bubbling behaviour. At bed moisture contents below 5-wt%, rapid divergence was seen in the S-statistic applied to both ECT and pressure fluctuation measurements. This indicates that a rapid change in dynamics occurs near the end of the drying process. This is possibly caused by the entrainment of fines at this time, or the build-up of electrostatic charge. <p>The use of the complimentary pressure fluctuation and ECT measurement techniques have identified changes occurring as a result of the reduction of moisture during the drying process. Both the localized changes in the voidage fluctuations provided by the ECT imaging and the global changes shown by the pressure fluctuation measurements indicate significant changes in the dynamic behaviour caused by the reduction of moisture during the drying process. These measurement techniques could be utilized to provide an on-line indication of changes in hydrodynamic regime. This information may be invaluable for the future optimization of the batch drying process and accurate determination of the drying endpoint.