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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Processos de separação fisica e secagem de inulina obtida a partir de raizes de chicoria (Cichorium intybus L.) / Process of physical separation and dryong of inulin obtained from (cichorium intybus L.)

Toneli, Juliana Tofano de Campos Leite 19 July 2006 (has links)
Orientadores: Fernanda Elizabeth Xidieh Murr, Kil Jin Park / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-06T19:15:33Z (GMT). No. of bitstreams: 1 Toneli_JulianaTofanodeCamposLeite_D.pdf: 4869380 bytes, checksum: 7fe096af8fbcfc3e8a543eeee680c10b (MD5) Previous issue date: 2006 / Doutorado / Doutor em Engenharia de Alimentos
92

Desenvolvimento de massa alimenticia funcional a base de extrato em po e farinha de Yacon (Polymnia sonchifolia) e farinha de arroz por processo de extrusão termoplastica / Development of functional pasta base extract powder and yacon (Polymnia sonchifolia) flour and rice flour by extrusion thermoplastic

Gonçalves, Priscila Vieira de Macedo 15 August 2018 (has links)
Orientador: Fernanda Paula Collares Queiroz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-15T04:31:19Z (GMT). No. of bitstreams: 1 Goncalves_PriscilaVieiradeMacedo_M.pdf: 1707723 bytes, checksum: f54b370c6c825cfbf3eac6859f666ca3 (MD5) Previous issue date: 2010 / Resumo: Objetivando atender a demanda por produtos com caracteristicas funcionais e isentos de gluten, na presente pesquisa foi proposto o desenvolvimento de uma massa alimenticia instantanea de arroz, por processo de extrusao termoplastica, enriquecida com farinha ou extrato em po de Yacon. Foram estudadas as melhores condicoes de processamento da farinha e do extrato de Yacon e o efeito dos parametros do processo de extrusao termoplastica (condicoes operacionais e composicao do material de alimentacao) na qualidade das massas alimenticias elaboradas. Os resultados obtidos mostraram que a temperatura mais adequada de secagem do Yacon in natura, no processamento da farinha, dentre as tres estudadas (40, 60 e 80oC), foi a de valor mais elevado (80 oC). No processamento do extrato em po de Yacon em mini spray dryer, os resultados mostraram que dentre as condicoes testadas, o maior rendimento ocorre em niveis mais baixos de temperatura (140 oC) e com o extrato mais diluido (11 oBrix). A analise dos efeitos dos parametros de extrusao termoplastica nas massas alimenticias foi realizada atraves da metodologia de superficie de resposta. A partir dos dados experimentais, utilizando-se dessa metologia de analise, nao foi possivel otimizar o processamento das massas, devido ao baixo coeficiente de correlacao encontrado. Entretanto, em geral, as massas alimenticias apresentaram boas caracteristicas (baixo tempo de cozimento, boa textura, aumento de massa satisfatorio), mostrando-se semelhantes as massas comerciais de farinha de trigo. Devido a isso, atraves do teste de Tukey, as massas que mais se aproximaram das massas comerciais de farinha de trigo, foram identificadas e submetidas a analise sensorial. Os provadores mostraram neutralidade quanto a aparencia das massas cruas, porem na degustacao da massa experimental, atribuiram notas inferiores em relacao a massa comercial. O produto desenvolvido nao diferiu estatisticamente da massa comercial no atributo textura, um dos mais importantes na analise de massas alimenticias. Entretanto, em relacao a cor das duas massas experimentais, os provadores preferiram a massa comercial que possui uma cor mais amarelada. A utilizacao do Yacon como materia-prima para produtos de maior valor agregado, portanto, e possivel; sendo que o processamento nao causa perda de seu carater funcional e sao obtidos produtos finais de boa qualidade, bem aceitos pelos consumidores. Em relacao ao processo de extrusao termoplastica, foi possivel o desenvolvimento de uma massa alimenticia de boa qualidade, com menor tempo de cozimento, entretanto, nao suficiente para ser classificada como instantanea / Abstract: In order to found the demand for products with functional and free of gluten, this research has proposed the development of a pasta instant rice by thermoplastic extrusion process, enriched with flour or extract powder Yacon. The best conditions for processing of flour and extract Yacon and the effect of process parameters of thermoplastic extrusion (operating conditions and composition of feed material) on the quality of pasta produced were studied. The results showed that the most suitable temperature for drying the yacon in order to obtain a flour. Considering the extract powder Yacon mini spray dryer, the results showed that among the conditions tested, the highest yield occurs at lower temperature (140 o C) and lower diluted extract (11 Brix). The effect of analysis of the parameters of thermoplastic extrusion in pasta was performed using the methodology of response surface. From the experimental data, using the Methodology of analysis was not possible to optimize the processing of the masses, due to the low correlation coefficient. However, in general, the pasta had good characteristics (low cooking time, good texture, increase in mass satisfactory), being similar to mass commercial wheat flour. Because of this, by the Tukey test, the mass closest to the mass commercial wheat flour, were identified and subjected to sensory analysis. The tasters showed neutrality of appearance of uncooked dough, but in tasting the experimental mass, gave notes below on the mass market. The product developed was not statistically different from the mass commercial attribute texture, one of the most important in the analysis of pasta. However, in relation to the color of the two experimental masses, the tasters preferred the mass commercial that has a more yellowish color. The use of yacon as a raw material for products with higher added value, so it is possible, and that processing does not cause loss of its functional character and are obtained final products of good quality, well accepted by consumers. For the thermoplastic extrusion process, it was possible the development of a mass of good quality food, less cooking time, however, not enough to be classified as Instantaneous / Mestrado / Mestre em Tecnologia de Alimentos
93

Estudo das CondiÃÃes de Secagem por AtomizaÃÃo de ConÃdios de Trichoderma harzianum LCB47 / Study of the drying conditions of Trichoderma harzianum LCB47 conidia by atomization

Virna Luiza de Farias 16 February 2009 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Nos Ãltimos anos, tem-se notado uma crescente preocupaÃÃo, em todo o mundo, com os problemas ambientais decorrentes das diversas atividades humanas, incluindo a agricultura. Nesse contexto, o controle biolÃgico constitui alternativa cada vez mais importante aos defensivos agrÃcolas quÃmicos. O controle biolÃgico consiste no emprego de um organismo (predador, parasita ou patÃgeno) que ataca outro que esteja causando danos econÃmicos Ãs lavouras. EspÃcies de Trichoderma sÃo reconhecidas como agentes de controle biolÃgico de doenÃas de plantas causadas por fungos fitopatogÃnicos, sendo a espÃcie T. harzianum uma das mais utilizadas. Os conÃdios sÃo os micropropÃgulos preferÃveis para uso no controle biolÃgico. Para a comercializaÃÃo de produtos de biocontrole, o produto formulado deve ser estÃvel ao armazenamento e manter a viabilidade dos esporos durante este perÃodo. A desidrataÃÃo dos esporos permite a preservaÃÃo do inoculo por um longo perÃodo de tempo, com alta viabilidade; e um dos mÃtodos utilizados para a secagem à a atomizaÃÃo (âspray dryerâ). Este trabalho teve como objetivo determinar as condiÃÃes mais adequadas de secagem de esporos de Trichoderma harzianum LCB47 em âspray dryerâ, de forma a preservar sua capacidade germinativa no produto desidratado. Conduziram-se experimentos para avaliar a necessidade do uso de encapsulante na secagem dos esporos. Estudaram-se, preliminarmente, as variÃveis temperatura de entrada e de saÃda do ar para avaliaÃÃo dos seus efeitos no nÃvel de sobrevivÃncia dos esporos e na umidade do pà final. Testou-se a influÃncia de diferentes materiais usados como encapsulantes, por meio da avaliaÃÃo da sua capacidade calorÃfica (Cp) e atravÃs do nÃvel de sobrevivÃncia resultante da secagem utilizando cada material. Estudaram-se os parÃmetros temperatura de entrada e de saÃda do ar, por meio de planejamento experimental, para avaliaÃÃo da sua influÃncia no nÃvel de sobrevivÃncia dos esporos e na umidade e atividade de Ãgua do pà final. Realizou-se uma avaliaÃÃo da estocagem dos esporos com relaÃÃo à retenÃÃo da sua viabilidade. Verificou-se que à necessÃrio a adiÃÃo de um encapsulante para a secagem dos esporos por atomizaÃÃo. O aumento da diferenÃa entre a temperatura de entrada e de saÃda do ar no processamento levou à elevaÃÃo da umidade do produto final, devido à necessidade do aumento da vazÃo de alimentaÃÃo da suspensÃo. Menores temperaturas de saÃda foram melhores quanto ao nÃvel de sobrevivÃncia dos esporos, sendo a de 55ÂC a que permitiu os melhores resultados. A goma arÃbica foi o encapsulante que apresentou maior capacidade calorÃfica, e foi o melhor com relaÃÃo à proteÃÃo dos esporos do calor do ar durante a secagem. O teor de encapsulante à o principal fator que afeta o nÃvel de sobrevivÃncia dos esporos, enquanto a umidade e a atividade de Ãgua do produto em pà sÃo fortemente influenciadas pela temperatura de entrada. Os esporos mantiveram sua viabilidade durante um mÃs quando armazenados sob refrigeraÃÃo. A melhor condiÃÃo de secagem de esporos de T. harzianum LCB47 foi 140/55ÂC de temperatura de entrada e de saÃda, respectivamente, utilizando maltodextrina como encapsulante. Nesta condiÃÃo o nÃvel de sobrevivÃncia mÃdio foi de 96%. / In recent years, the world is having a growing concern regarding human activity towards the environment, including the problems related to agriculture. Biological control is, nowadays, a viable and important alternative to chemical defensives. Biological control consists of the used of a living organism (predator, parasite or pathogen) that attacks other unwanted organism without causing damages to the crops. Trichoderma species are known as biological control agents to plant diseases caused by phytopathogenic fungi. T. harzianum is the most applied agent. Conidia are the preferred micropropagules for biological control. For commercialization, biological control products should be stable during storage and should maintain its viability during this period. Drying of the spores allows the preservation of the inoculums for a long period of time maintaining high viability. One of the most used methods for drying spores is spray drying. This work aims to determine the best operating conditions to dry Trichoderma harzianum LCB47 spores, using spray drying, to keep the germinative capacity of the dehydrated product. Experiments were carried out to evaluate the need for encapsulates during drying of the spores. Initially, the inlet and outlet air temperatures in the spray drier were evaluated concerning the survival of the spores and the final dried product moisture content. Several raw materials were tested as encapsulates by means of evaluating their heat capacity (Cp) and by evaluating the level of survival after drying the spores. The inlet and outlet air temperature were evaluated using a factorial design. An evaluation of the viability of the spores during storages was also carried out. The results show the need of the addition of encapsulates for drying spores using spray-drying. The increase between the inlet and outlet air temperatures in the spray-drier resulted in an increase in the final moisture content of the product because of the need to increase the feed flow rate in the spray-drier. Lower outlet air temperatures resulted in higher levels of survival of the spores, and the temperature of 55ÂC allowed the best results. Arabic gum was the encapsulate that presented the highest heat capacity and that resulted in the highest protection of the spores during drying. The amount of encapsulate was the most significant factor that influenced in the survival of the spores, while the final moisture content and the water activity were most significantly influenced by the inlet temperature of the air. The spores maintained their viability for a month under refrigeration. The best operating condition to dry spores of T. harzianum LCB47 was obtained applying inlet and outlet air temperatures of respectively 140 and 55ÂC, and using maltodextrin as encapsulate. Under this condition, the mean level of survival of the spores was 96%.
94

Tomate seco obtido por energia solar e convencional a partir de mini-tomates congelados / Dried tomatoes produced by solar and conventional energy from mini-tomatoes frozen

Egly Sturion Alessi 18 October 2010 (has links)
O tomate constitui-se uma das hortaliças mais exploradas cientificamente, devido à sua importância comercial. O tomate pode, através de processamento adequado, dar origem a inúmeros produtos, alguns deles de elevado consumo no Brasil. Depois da boa aceitação do tomate cereja pelo consumidor, um novo segmento de mini-tomate, chamado Grape, começa a despontar nos mercados brasileiros. O destaque é o híbrido Sweet Grape, que está agradando ao gosto do consumidor e animando agricultores que aderiram às experiências com a nova cultivar. Seu teor de sólidos solúveis chega a 10 °Brix e tem menos acidez, comparado a outras variedades, as quais contem entre 4 e 5 °Brix. Nesse trabalho foi avaliado o processo produtivo do tomate seco, a partir de mini-tomates sweet grape, congelados desidratados em secador solar e convencional, visando obter um alimento seguro do ponto de vista microbiológico, físico-quimica, instrumental cor e aceitabilidade) Os tomates cereja tipo Sweet Grape, foram secos até teores de umidade entre 35% e 0%, e observadas suas mudanças em relação aos tomates in natura , e seu comportamento nos períodos de armazenamento após processados de 0, 30, 60 e 90 dias, verificando assim a sua estabilidade. Foi ainda caracterizado o fruto in natura e submetido a um précongelamento para uma previa perda de água facilitando a secagem. A avaliação da qualidade do produto foi realizada através das análises microbiológicas, físico-químicas, composição centesimal e sensorial. Houve diferença significativa entre os secadores, elétrico e solar, para todos os parâmetros analisados, porém não houve alteração significativa para o período de armazenamento. Em relação à avaliação sensorial, o tomate seco ao sol obteve melhor aceitação entre os provadores / The tomato is one of the vegetables are more scientifically investigated, due to its commercial importance. The tomato can, through appropriate processing, giving rise to numerous products, some of high consumption in Brazil. After the good acceptance by consumers of cherry tomatoes, a new segment of mini-tomato, called Grape, begins to emerge in the Brazilian markets. The highlight is the hybrid Sweet Grape, which is pleasing to the taste of consumers and encouraging farmers adhered to experiment with new cultivars. Your soluble solids content reaches 10 ° Brix and has less acidity compared to other varieties, which contain between 4 and 5 ° Brix. In this study we evaluated the production process of dried tomato, from mini-sweet grape tomatoes, frozen and dehydrated in conventional solar dryer was used to obtain a food safe from microbiological point of view,. physico-chemical, instrumental color and acceptability) Cherry Tomatoes Sweet Grape type, have been dried to moisture contents between 35% and 50%, and observed their changes for tomatoes in nature, and their behavior during periods of storage after processed 0, 30, 60 and 90 days, thus confirming its stability. It was further characterized the fresh fruit and undergo a pre-freeze to a predicted loss of water facilitating drying. Assessing the quality of the product was carried out by microbiological, physicochemical, chemical composition and sensory. There were significant differences between the dryers, electric and solar, for all parameters analyzed, but no significant change for the period of storage. Regarding the sensory evaluation, the sun-dried tomatoes the best won acceptance among judges
95

Caracterização e secagem em spray dryer de leite em pó integral com lactose hidrolisada

Torres, Jansen Kelis Ferreira 25 August 2016 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-10T15:21:25Z No. of bitstreams: 1 jansenkelisferreiratorres.pdf: 1860554 bytes, checksum: b932669c5e7fa0097c7d4c4ffd613064 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-11T11:38:57Z (GMT) No. of bitstreams: 1 jansenkelisferreiratorres.pdf: 1860554 bytes, checksum: b932669c5e7fa0097c7d4c4ffd613064 (MD5) / Made available in DSpace on 2017-04-11T11:38:58Z (GMT). No. of bitstreams: 1 jansenkelisferreiratorres.pdf: 1860554 bytes, checksum: b932669c5e7fa0097c7d4c4ffd613064 (MD5) Previous issue date: 2016-08-25 / A indústria de alimentos tem como desafio e oportunidade desenvolver novos produtos com reduzido ou baixo teor de lactose, a fim de atender uma crescente populaçào de portadores de má digestão da lactose. O leite em pó enfrenta grande desafio tecnológico devido ao fato da secagem dos produtos com lactose hidrolisada ser extremamente desafiadora por apresentar maior número de moléculas (glicose e galactose) no estado amorfo tornando o produto altamente higroscópico, influenciando na produtividade, no entupimento das câmaras e na conservação dos pós. O objetivo deste estudo foi avaliar o efeito de diferentes níveis de hidrólise enzimática da lactose, 0%, 25%, 50%, 75% e >99%, na produção e estocagem de leite em pó integral utilizando como ferramentas de caracterização dos produtos fabricados em planta piloto, análise de composição, microscopia eletrônica de varredura (MEV), análise de tamanho do diâmetro hidrodinâmico das partículas por difração laser (LS) após reidratação em água, além da espectroscopia Raman dos pós em ambiente com 75,5% de umidade relativa do ar, visando monitorar a transição vítrea da lactose residual. Foi possível verificar influência direta do aumento da hidrólise nos valores de umidade dos pós obtidos, assim como o impacto na aderência dos mesmos na câmara de secagem, devido à aglomeração primária das partículas caracterizada pela MEV. As análises de LS demonstraram também o efeito do aumento da hidrólise na diminuição da população das partículas entre 40 e 500 μm, que denota forte influência na capacidade de reidratação dos produtos. Com o uso da espectroscopia Raman foi possível caracterizar o estado físico dos carboidratos nas partículas dos pós, utilizando a análise de componentes principais para a região espectral de 1200 a 400 cm-1, a qual identificou que os produtos com 25%, 50%, 75% e > 99% de hidrólise não apresentaram efeito de cristalização no ambiente com umidade controlada por 6 semanas. A hidrólise da lactose em glicose e galactose impacta a secagem de produtos lácteos por promover maior adesão nos equipamentos, maior tendência ao escurecimento, diminuição da solubilidade e modificação da microestrutura dos pós. Em produtos lácteos contendo lactose observa-se a formação de cristais de lactose quando estes são submetidos a condições favoráveis a transição vítrea. A técnica de espectroscopia Raman combinada com quimiometria possibilita afirmar que produtos lácteos hidrolisados quando submetidos a condições favoráveis a transição vítrea não apresentam a formação de cristais de açúcares. / The food industry has the challenge and the opportunity to develop new products with reduced or low lactose content in order to meet the needs of a growing mass of people with lactose maldigestion. Milk powder is also inserted into these new trend but this product still faces major technological challenge due to the fact that drying of products with hydrolyzed lactose is extremely challenging mostly because of a higher number of molecules (glucose and galactose) in the amorphous state which makes it quite a highly hygroscopic product thus influencing productivity, post-conservation not to mention the undesirable and also inevitable technological problem of the constant clogging of drying chambers. The aim of this study was to evaluate the effect of different levels of enzymatic hydrolysis of lactose, 0%, 25%, 50%, 75% and > 99% in production and storage of whole milk powder using as analitical parameters in the pilot plant the following: composition analysis, scanning electron microscopy (SEM), analysis of hydrodynamic diameter of particles by laser diffraction (LS) after rehydration in water plus Raman spectroscopy of powders in 75.5% air moisture environment seeking to monitor the glass transition of the residual lactose. It was possible to verify direct influence of increased hydrolysis to moisture values of the powders as well as the impact on the adhesion thereof into the drying chamber due to primary agglomeration of particles characterized by SEM. LS analysis also has shown the effect of increasing hydrolysis in the reduction of the population of particles between 40 and 500 nanometers demonstrating a strong influence on the rehydration capacity of the products. By means of Raman spectroscopy it has been possible to characterize the physical state of the carbohydrates in the powder particles, using principal component analysis for the 1200-400 cm-1 spectral range, which identified that products with 25%, 50%, 75% and > 99% hydrolysis have shown no crystallization effect in the controlled humidity environment for 6 weeks. The hydrolysis of lactose into glucose and galactose impacts drying milk products to promote greater adhesion to equipment more prone to darkening, decreased solubility of the microstructure after modification. In dairy products containing lactose can observe the formation of lactose crystals when they are subjected to favorable glass transition. The Raman spectroscopy technique combined with chemometrics enables us to state that hydrolyzed milk products when subjected to favorable conditions the glass transition do not have the formation of sugar crystals.
96

Waste from instant tea manufacturing as a fuel for process steam generation

Somasundara, D. H. G. S. R. January 2017 (has links)
An existing furnace oil fired boiler is used to supply process steam to an instant tea manufacturing factory. The instant tea is manufactured the Broken Mixed Fannings (BMF) through extraction and other required processes. The average steam consumption of the plant is 6000 kg/h at 10 barg pressure. During the process, tea waste is generated at a nominal rate of 50,000 kg/day, about 2000 kg/h at around 70% MC content on wet basis. At the moment this waste tea is either dumped in the surrounding area by spending money or sent to landfilling purposes, which create environmental issues.   The tea waste coming out at 70% MC wet basis, is looked at to press through continuous belt press to reduce the moisture content to about 55% on wet basis. The water removed from this pressing process is sent to effluent treatment plant at the factory. The output from the belt press is sent to a steam operated  The average generation of tea waste from the instant tea manufacturing process process is about 2000 kg/h, after pressing in the belt press an output rate of about 1,400 kg/h at 55% MC. This amount of tea waste at 55% MC is sent to a rotary steam tube dryer and the MC is reduced from 55% to 30% and the output rate from the steam tube dryer is about 857 kg/h. The amount of steam consumed by the rotary steam tube dryer at 6 barg pressure is 760 kg/h. Then the tea waste from the rotary tube dryer is mixed with firewood of 30% MC and fed to the boiler to generate process steam, out of which 857 kg/h steam at 6 barg pressure is sent back to the rotary steam dryer. From tea waste alone, a steam amount of 2,472 kg/h can be supplied after giving steam to the rotary steam dryer. The balance steam amount of 3,528 kg/h for the process requirement is supplied by burning additional firewood at 30% MC content. The tea waste fuel and firewood in combination have an overall moisture content of 30% on wet basis. The boiler is rated at 10,000 kg/h F & A 100 deg C with an actual generating capacity of about 9000 kg/h at 10 barg operating pressure at 70 deg C feed water temperature. By implementing the combination of belt press, rotary steam tube dryer and firewood boiler in place of the existing furnace oil fired boiler, an annual monetary saving of 168 Mn SLR/year can be achieved with a simple payback period of 21 months which is a highly feasibly project.
97

Optimisation des opérations de séchage dans la chaîne de fabrication du PVC en poudre. Expérimentation, simulation et modélisation. / Optimization of drying operations in powder PVC production line. Experimentation, simulation and modeling.

Aubin, Antoine 27 June 2014 (has links)
Lors de la production du PVC en poudre, après l’étape de polymérisation en suspension, on obtient une bouillie constituée d’un mélange de grains macroporeux de taille comprise entre 100 et 200 μm et d’eau. L’étape de centrifugation permet la séparation de la phase liquide exprimable et la production d’un milieu poreux humide appelé « gâteau ». La teneur en eau du gâteau ainsi formé est de 30 % de la masse du produit anhydre. Le séchage du gâteau de filtration se fait dans un séchoir Flash (séchoir pneumatique) couplé à un séchoir à lit fluidisé. Cette opération, très gourmande en énergie et donc très impactante en termes d’émission de Gaz à Effet de Serre (GES), représente 30% du coût de fabrication et 50% des émissions de CO2. Ce travail, réalisé dans le cadre d’une collaboration avec le groupe INEOS ChlorVinyls, est consacrée à l’étude de l’étape de séchage thermique, et à la réalisation d’outils expérimentaux et théoriques permettant d’optimiser le fonctionnement et de réduire la consommation énergétique de cette étape. Dans ce but, l’étude du séchage du PVC est réalisée à l’échelle d’une particule isolée d’une part, et à l’échelle du procédé industriel d’autre part. La détermination expérimentale de la cinétique de séchage est effectuée en immergeant une quantité de produit humide (gâteau de filtration) dans un lit fluidisé de grosses particules inertes et chaudes (billes de verre), et permet d’étudier l’influence de différents paramètres sur la cinétique d’évaporation. Les résultats ont montré que cette cinétique est limitée par les processus d’évaporation à l’intérieur et à la surface des particules. Du point de vue théorique, un modèle dont le principe repose sur les bilans de matière et de chaleur à l’échelle du grain de PVC, couplés aux bilans sur le séchoir à lit fluidisé, a été élaboré. La comparaison des résultats de ce modèle avec les résultats expérimentaux a permis de vérifier la validité de la loi cinétique ainsi établie. Finalement, cette loi a été intégrée dans un modèle simulant le séchoir pneumatique industriel. Les résultats théoriques sont comparés à des mesures réalisées sur un séchoir pneumatique industriel équipé de capteurs de pression, d’humidité et de température. Les résultats de cette étude ont permis de proposer une nouvelle stratégie de régulation du séchoir pneumatique ainsi que des modifications du procédé, ne nécessitant pas d’investissement. L’ensemble de ces propositions a permis de réduire d’environ 30% la consommation énergétique pour un rendement de séchage équivalent. / In a PVC powder production line, the step of suspension polymerization produces a mixture of macroporous particles and water, called “slurry”. The mean particle size varies between 100 and 200 µm. The centrifugation step eliminates most of water content and produces a wet porous medium called “cake”. The water content of the cake is about 30% of the dry product mass. Drying operations take place in a Flash dryer (pneumatic dryer) coupled with a fluidized bed dryer. These operations, which consume a lot of energy and produce greenhouse gas, represent 30% of the production cost and 50% of the CO2 emissions. This work, realized in collaboration with INEOS ChlorVinyls group, is devoted to the study of the thermal drying step and to the realization of experimental and theoretical tools in order to optimize and reduce the energy consumption of this step. The study of the drying step is realized, on the one hand, at the particle scale and, on the other hand, at the industrial dryer scale. The particle scale drying kinetic is obtained by immersing a sample of wet product in a fluidized bed of warm inert particles (glass beads), and enables to study the influence of different parameters on the evaporation kinetic. The results have shown a limitation of this kinetic by the evaporation process both inside the particles and on their outer surface. In a theoretical way, a model based on mass and heat balances at particle scale coupled with fluidized bed balances, has been developed. The kinetic law developed is validated by the comparison between the results of this model and the experimental results. Finally, this law is integrated in a model simulating the industrial pneumatic dryer. The theoretical results are compared to the measurements realized on an industrial pneumatic dryer, equipped with several pressure, humidity and temperature sensors. The results of this study lead to the proposition of a new regulation strategy for the pneumatic dryer and some zero-investment modifications of the process. All these propositions enable an energy consumption reduction of 30%.
98

Regenerace tepla a vody z proudu odpadního vzduchu / Regeneration of heat and water from the exhaust air stream

Jankůj, Tomáš January 2019 (has links)
This thesis deals with the process of wood drying. It is a method of removing excess water from wood. Drying can be divided into two basic types. The first type is natural drying. The material is dried without the presence of foreign energy source. This type depends only on climatic conditions and the amount of sunlight. Another type is artificial drying, where is pre-sent a foreign energy source, such as a biomass boiler. The second type is significantly faster than the first. The second type of drying uses a device called a wood dryer. There are a lot of types of wood dryers, the most widely used are kiln dryer, belt dryer, rotary drum dryer. In these devices, the thermal energy is transferred to the drying materials by the flowing warm drying medium (convection). The heat is transferred to the drying medium in a heat exchan-ger. Because the drying process is very energy demanding, it is appropriate to reduced the required energy. This can be done by regenerating heat and water. In the heat exchanger, part of the heat can be gained from the flowing exhaust medium. If a condensation of evaporated water in the exchanger occurs, the latent heat of the water is released. The gained heat is used to preheat the drying medium and thereby to reduce the required energy.
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CFD modelování toku partikulárních látek v rotační peci / CFD modelling of granular flow in rotary kiln

Slowik, Roman January 2020 (has links)
This work deals with modeling the flow of particulate matter in rotary kilns. For this purpose, a combined CFD and Discrete Element Method (DEM) model was used. Using Ansys Fluent software, several simulations were performed in order to determine the mean residence time and movement of the material in the rotary drum dryer. Results of the computational model were used to develop a regression model of the mean residence time and compared to the values as given by empirical equations. Furthermore, a simplified sensitivity analysis was performed for the selected input parameters of the model such as the stiffness constant, air mass flow rate and the particle size.
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Příprava vysokohodnotného sádrového pojiva / Preparation of high-valueable gypsum binder

Hájková, Iveta January 2012 (has links)
This work is oriented on the preparation of high-voluable sulphate binder based on gypsum waste. One of the potential mineral resources in Moravia is Pregips chemical gypsum, produced by Precheza. This is the raw material, which is characterized by high purity, high quality and is economically acceptable. Beta burned gypsum plaster from this, however, need to modify due to suppression of the high needs of water mixing, which is determined by its morphology. The need for mixing water has a large impact on the strength of gypsum binders. Therefore it is necessary to find a suitable additive, which would reduce the coefficient of water in the preparation of porridge normal consistency.

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