Made available in DSpace on 2016-06-02T19:56:58Z (GMT). No. of bitstreams: 1 6664.pdf: 4562284 bytes, checksum: 86f11a0656db23f159ea20aca3d6a8c6 (MD5) Previous issue date: 2015-02-27 / Universidade Federal de Minas Gerais / In Brazil, ethanol is produced from fermentation route, being a process well consolidated and largely used for decades in the production units without facing significant changes in its design. In order to increase the productivity in this process, few studies have evaluated ethanol recovery using CO2 to strip it from the vine of the fermentation stepwise and from the vine without yeasts. Thus, in the fermentation stepwise, there is a possibility of prolonging the yeast s activities, by maintaining the ethanol concentration below the inhibition limit of action of this type of organism for more time, causing a higher ethanol production in this step. Besides that, the stripped ethanol from the vine without yeast arises a san alternative to the first distillation step, impacting in a reduction of the energy consumption in the process due to the least necessity of water vapor use. Under these conditions, the generated gas would be mainly a mixture between CO2 gas and ethanol-water vapor. Because of this, it was proposed to evaluate the ethanol recovery in this gaseous mixture by absorption unit operation. Then, it was assembled a system containing a saturated gaseous mixture generation in ethanol, passing continuously in countercurrent flow with the recirculated liquid into a absorption column, before being released to the environment. Through recirculated liquid samples over time, it was possible to follow the effects caused of some absorbents indetermined concentrations and determined gaseous mixture and absorbent flows. As absorbents were evaluated aqueous solutions of ethylene glycol, diethylene glycol and glycerol. With the work results was possible to compare solute concentration over time in each absorbent, to measure the ethanol recovery level, to estimate the controller phase(gaseous or liquid) and to calculate the overall volumetric mass transfer coefficients of the liquid phase (KLa), proposing correlations for that and for the ethanol recovery level in the studied conditions. Ethanol concentration until 63% (w/w) and recovery values closer than90% were observed. Besides that, it was proposed a method to determine KLa and it were got and evaluated 24 equations to estimate it and more 22 in order to estimate the ethanol recovery level. / No Brasil a produção de etanol é realizada pela rota fermentativa, sendo um processo amplamente consolidado e empregado há décadas nas unidades de produção sem sofrer alterações significativas no seu formato. A fim de aumentar a produtividade nesse processo, alguns estudos avaliaram a recuperação do etanol utilizando CO2 para arrastá-lo do vinho da etapa de fermentação alcóolica e do vinho delevedurado. Com isso, no meio fermentativo, há a possibilidade de prolongar a atividade das leveduras, ao manter a concentração do etanol presente no meio abaixo do valor limite de inibição de ação deste tipo de organismo por um período maior de tempo, acarretando uma maior produção de etanol nesta etapa. Além disso, o arraste do etanol do vinho delevedurado surge como uma alternativa à primeira etapa de destilação, impactando em uma redução do consumo energético no processo pela menor necessidade de uso de vapor d água. Nessas condições,uma mistura entre gás CO2 e vapores de água e etanol é gerada. Desta forma, neste trabalho foi avaliada a recuperação do etanol presente nessa mistura gasosa pela operação unitária de absorção. Assim, montou-se um sistema com a geração de uma mistura gasosa saturada e metanol, passando continuamente em fluxo contracorrente com o líquido absorvente recirculado em uma coluna de absorção, antes de ser liberada para o ambiente. Por meio de amostras do líquido recirculado com o passar do tempo, foi possível acompanhar os efeitos causados pelo uso de alguns absorventes em determinadas concentrações, em diferentes vazões da mistura gasosa e do absorvente. Como absorventes foram avaliadas soluções aquosas de etilenoglicol, dietilenoglicol e glicerol. Através dos resultados do trabalho foi possível comparar a concentração do soluto ao longo do tempo em cada absorvente, medir a recuperação do etanol em cada ensaio, inferir sobre a etapa controladora (gasosa ou líquida) e calcular os coeficientes globais volumétricos de transferência de massa da fase líquida (KLa), propondo correlações para as estimativas destes e do valor de recuperação de etanol nas condições estudadas. Concentrações de até 63% em massa de etanol e recuperações próximas de 90%foram observadas. Além disso, foi proposto um método para a determinação de KLa e obtidas e avaliadas 24 equações para estimá-lo e 22 para estimar a recuperação de etanol.

Background and Aims: Volatile loss of carbon dioxide, ethanol, esters and other compounds occurs during wine fermentation. When collected nondestructively, valuable ethanol and aroma compounds can be preserved for various uses while mitigating production restrictions and regulations regarding volatile organic compound (VOC) loss from wine production. Knowledge of the volume of volatiles lost during wine fermentation contributes to a better understanding of the magnitude of possibilities for resource recovery/aroma recovery, the implications of volatile loss on wine composition as well as a more clear understanding of the possible effect of alcoholic fermentation on air quality. The aim of this study was to contribute to a better understanding of how the loss of volatiles from wine fermentation varies with temperature. Methods and Results: Temperature controlled microscale fermenters were developed and infrared detection technology was adapted to study the effect of temperature on volatile loss. Results are presented for the rates and volumes of volatile loss from the fermentation of California Syrah at constant temperatures (17, 23, 27, 33˚C) in 1.9L containers. Observed volatile losses are compared to theoretical losses based on kinetic and stoichiometric principals. Each ferment started with 1200g of fruit and was adjusted to 23.5˚B. Following Brix adjustment, final volumes ranged from 1129.16mL to 1160.10mL. Conclusion: The loss of VOC from fermentation increases exponentially with temperature. Total VOC and CO2 loss appears to be slightly less than theory predicts. Significance of the Study: A significant loss of compounds occurs during wine fermentation. Commercial and environmental benefits may be achieved if efforts are made to recover and make use of these otherwise wasted compounds. Funding provided by the Agricultural Research Initiative, California State University.