The influence of operation parameters on the drying of spherical porous particles containing a mixture of solvents evaporating into nitrogen in a continuously worked vibrated fluid-bed dryer was studied. A simulation based on the analytical solution to heat and mass transfer equations was applied and modifications were suggested.   Four different ternary liquid mixtures were selected: Acetone-Chloroform-Methanol (ACM), Ethanol- 2-propanol-Water (EIpW), Water-Ethanol-Ethyl Acetate (WEEa) and Ethanol-Methylethylketone- Toluene (EMekT). For the solid, physical properties of Pyrex was used.   Comparison of composition- and temperature- profiles indicated that there is no resistance against heat transfer within the solid and that the heat transfer is much faster than mass transfer.   Selectivity diagrams were drawn. The results indicated that selectivity is an important parameter in predicting the drying behavior.   The retention ratio was studied as performance parameter. Its variation was studied in response to changes in operation parameters, including gas velocity and temperature, as well as solid temperature and particle size.   A  modification  to  the  model  was  examined  by  assuming  a  liquid-content-dependent  diffusion resistance factor. It was observed that implementing such an assumption yields decreased values for retention ratios.   The  effect  of  vibration  on  heat  and  mass  transfer  coefficients  was  included  using  a  correlation suggested by Sbrodov and the resulting effect on retention ratio was examined. / Inverkan   av   driftparameter  på  torkning  av   sfäriska  porösa  partiklar  som   innehåller lösningsmedelblandningar som avdunstar i kväve i en kontinuerligt viberande fluidbädd-tork studerades.  En  simuleringsmodell  baserad  på  den  analytiska  lösningen  till  värme-  och materieöverföringsekvationerna användes och ändringar föreslogs.   Fyra  olika  tärnar  vätskeblandningar  valdes:  aceton-kloroform-metanol(ACM),  etanol-2- propanolvatten,(EIpW),     vatten-etanol-etylacetat     (WEEa)     och     etanol-metyletylketon- toluen(EMekT). För den fasta fasen användes fysikaliska egenskaper liknande Pyrex.   Sammansättnings-  och  temperatur-profiler  visade  att  det  inte  finns  något  motstånd  mot värmeöverföring  i  den  fasta  fasen  och  att  värmeöverföringen  sker  mycket  snabbare  än materieöverförningen.   Selektivitetsdiagram ritades. Resultaten indikerar att selektivititen är en viktig parmeter för att förutsäga beteendet vid torkning.   Retentionsförhållandet  användes  som  ett  prestandamått.  Dess  variation  med  avseende  på förändringar av  driftsparmetrar,  bland  annat  gasen  hastighet  och  temperatur  samt  den  fasta  fasens temperatur och partikelstorlek, studerades.   En modifiering av modellen undersöktes genom att införa en vätskehalts-beroende faktor för diffusionsmotståndet. Detta minskade värdena på retentionsförhållandena.   Vibrationens inverkan på värme- och materieöverföring infördes genom att använda Sbrodov samband, och den resulterande effekten på retentionsförhållandet observerades.

Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study. Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas-liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa. The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used. ii These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17β-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17β-estradiol (E2) converted to estrone (E1) at the beginning of the reaction. A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions.

Orientador: Eduardo Augusto Caldas Batista / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-16T00:41:25Z (GMT). No. of bitstreams: 1 Sanaiotti_Guilherme_M.pdf: 2559183 bytes, checksum: 49e8656b4f14ee53f65b1a0dc45c232d (MD5) Previous issue date: 2010 / Resumo: A desacidificação de óleos vegetais por extração líquido-líquido apresenta-se como uma alternativa atraente às elevadas perdas e gastos energéticos usualmente encontrados nos métodos de refino alcalino e por destilação de ácidos graxos livres, respectivamente. A utilização de insumos provenientes de fontes renováveis e a ausência de geração de resíduos conferem ainda caráter ambiental pertinente ao processo. Modelos descritivos de perfis axiais de composição de fases, fundamentados em balanços populacionais de gotas e transferência de massa multicomponente, são essenciais para o desenvolvimento de métodos de design e scale up de colunas de extração líquido-líquido. A principal finalidade deste trabalho foi avaliar correlações, métodos e diretrizes para o dimensionamento de colunas de discos rotativos aplicadas à desacidificação de óleo de soja. Dados de composições de fases em equilíbrio, densidades, viscosidades e tensões interfaciais de sistemas compostos por óleo de soja + ácido linoléico comercial + etanol + água a 298,2 K foram determinados experimentalmente a frações mássicas de água no solvente iguais a 5,00 %, 8,00 %, 11,00 % e 14,00 %. Os desvios relativos absolutos entre os valores experimentais e os estimados por meio de equações empíricas foram inferiores a 6,36 %. Perfis de composição de fases quantificados por 3 diferentes modelos foram correlacionados a dados experimentais existentes na literatura, determinados em uma coluna de discos rotativos (RDC) com 5,0 cm de diâmetro, utilizada para a desacidificação de óleo de milho. Os desvios relativos absolutos entre as frações mássicas de ácidos graxos livres experimentais e as obtidas por simulação foram próximos a 20 %. Em um estudo hipotético, colunas de discos rotativos foram dimensionadas sob diferentes condições operacionais e teores de água no solvente, ao se considerar vazões mássicas de óleo de soja bruto equivalentes a 11,488 ton¿h-1. Os fatores avaliados apresentaram efeito significativo sobre as dimensões calculadas, ao obterem-se diâmetros de coluna compreendidos entre 2,29 m e 2,94 m, bem como alturas de zona de extração entre 5,89 m e 69,07 m. Para sistemas compostos por óleos vegetais + ácidos graxos livres + etanol + água, os efeitos das variáveis operacionais de colunas mecanicamente agitadas sobre os perfis de tamanhos de gotas e de composições de fases são ainda pouco elucidados. Desta forma, este estudo revela-se de grande importância para a efetiva inserção dessa alternativa de processo no refino de óleos vegetais, ao proporcionar com que os métodos de design e scale up elevem-se a patamares quantitativamente mais precisos / Abstract: Deacidification of vegetable oils by liquid-liquid extraction seems to be an attractive alternative to high oil losses and energy costs typically found in alkali refining and by distillation of free fatty acids, respectively. The use of raw materials attained from renewable sources and the absence of residuals provides also a relevant environmental feature to the process. Descriptive models of phase composition profiles, based on drop population balances and multicomponent mass transfer, are essential for the development of design and scale up methods of liquid-liquid extraction columns. The major aim of this work was to evaluate correlations, methods and guidelines for sizing rotating disc columns applied to soybean oil deacidification. Equilibrium phase compositions, densities, viscosities and interfacial tensions for systems composed of soybean oil + commercial linoleic acid + ethanol + water at 298.2 K were experimentally determined using alcoholic solvents with water mass fractions of (5.00, 8.00, 11.00 and 14.00) %. The relative absolute deviations between experimental data and those calculated from empirical equations were lower than 6.36 %. Phase compositions profiles, quoted using 3 different models, were correlated to experimental data described in literature, determined in a rotating disc column (RDC) with 5.0 cm in diameter, which was used for corn oil deacidification. The relative absolute deviations between the free fatty acid mass fractions experimentally determined and those calculated from simulation were around 20 %. In a hypothetical study, rotating disc columns were sized for different operational conditions and water mass fractions in the solvent, considering crude soybean oil mass flow rates of 11.488 ton¿h-1. The studied factors were significant in the calculated dimensions, once the column diameters varied from (2.29 to 2.94) m and the column heights ranged from (5.89 to 69.07) m. For systems composed of vegetable oils + free fatty acids + ethanol + water, the effects of operational conditions of mechanically stirred columns on drop size and phase compositions profiles are still not well elucidated. Thus, this work becomes of great importance in the effective application of this alternative process in vegetable oils refining, shifting of column design and scale up methods to a quantitatively more precise level / Mestrado / Mestre em Engenharia de Alimentos