Orientador: Florencia Cecília Menegalli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-20T07:44:45Z (GMT). No. of bitstreams: 1 Souza_DiogoOtaviodeCastro_D.pdf: 2512415 bytes, checksum: cc03ff39105bf1fed4d6dae52c95bbce (MD5) Previous issue date: 2012 / Resumo: A granulação é um processo de aumento de tamanho de pós finos, que pode ser utilizado na indústria de alimentos para aumentar a qualidade de alimentos em pó, pelo aumento da sua dispersibilidade e solubilidade em líquidos. O modelo de balanço populacional (MBP) é normalmente utilizado para modelar este processo. Entretanto, nos trabalhos existentes, o MBP não leva em consideração as perdas de partículas no processo por elutriação e incrustação, muito relevantes para granulação de sucos em pó. Além disso, não existe na literatura correlações para estimar estas constantes com base nas condições operacionais do equipamento e nas características das partículas. Diante disso, o objetivo deste trabalho foi o estudo do impacto das condições operacionais no modelo de balanço populacional, durante a granulação de suco de goiaba em pó, em leito fluidizado. Diversos experimentos foram realizados de forma a adquirir os dados que alimentaram os modelos matemáticos desenvolvidos. Estes dados foram obtidos fora das zonas de máximo rendimento a fim de se obter um modelo mais abrangente, que pudesses simular o processo de granulação em todas as condições de processo. Foram desenvolvidas e validadas correlações para estimativa da taxa de elutriação, para estimativa das constantes de aglomeração e de quebra do MBP. Além disso, foi desenvolvido um modelo para estimativa da massa incrustada de partículas. Os modelos se mostraram capazes de estimar o rendimento do processo, os valores de diâmetro médio e da distribuição de tamanho de partículas. Foram feitas simulações alterando a velocidade do ar de fluidização, a vazão de ligante, o diâmetro médio inicial da distribuição, o formato da distribuição e a massa total de partículas. A análise das simulações realizadas sugere que as condições ótimas precisam ser avaliadas para cada distribuição de tamanho e para cada quantidade de partículas no equipamento, não somente para cada tipo de produto. De modo geral, os modelos desenvolvidos se mostraram adequados para aumentar a compreensão do processo de granulação e para obtenção de ótimos de processamento. Cabe ressaltar a necessidade de futuras investigações para verificar a aplicação destes modelos com outros tipos de material particulado e em outras faixas de operação / Abstract: Granulation is a size-enlargement process, in which small particles are agglomerated together. It is used in the food industry to increase the quality of food powder, by increasing its solubility. The population balance model (PBM) is a widely used model for this process. However, it is usually applied without account losses in the process by elutriation and wall deposition, which are very important for granulation of powdered juices. In addition, there is no correlation in the literature able to estimate the constants of the model from the operational conditions and from the particles¿ characteristics. The objective of this work was to study the impact of operational conditions into the population balance model for the granulation of guava juice powder, in a fluidized bed. Several experiments were performed in order to acquire data that fed the mathematical models developed in this work. These data weren¿t obtained from the zones of maximum process yield in order to achieve a more comprehensive model, which could simulate the granulation process in all process¿ conditions. It was developed and validated a correlation for the estimation of the rate of elutriation, a model for the estimation of the particles¿ wall deposition, a correlation for estimation the constants of agglomeration and for estimation of the breakage constant of the PBM. The models predicted, with good accuracy, the process yield, the mean diameter and particle size distribution. Simulations were made by changing the fluidizing air temperature, the liquid binder flow rate, the fluidizing air velocity, the initial mean diameter, the shape of the particles size distribution and the total mass of particles. The analysis of the simulations suggests that the optimal conditions must be evaluated for each kind of particle size distribution and for each mass of particles into the equipment, not only for each type of product. The models developed showed to be suitable to increase the understanding of the granulation process and to obtain process¿ optimal conditions. It is worth emphasizing the need of further research to verify the application of these models for others types of particles and others operational ranges / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Orientador: Florencia Cecilia Menegalli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T04:16:57Z (GMT). No. of bitstreams: 1 Dacanal_GustavoCesar_M.pdf: 2777471 bytes, checksum: b80c63182ebc03483ba92c58dcd7ddb9 (MD5) Previous issue date: 2005 / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

The main purpose of this study was to optimise the grain size distribution of the raw material mixture for the production of iron sinter. It well known that the constitution of the sinter mix is based on the knowledge of chemical composition and grain size distribution. Although Mittal Vanderbijlpark has fixed specifications on the physical and chemical properties of the sinter for optimal blast furnace performance, the particle size distribution of the sinter mix has not yet been optimized. This was achieved by using the granulation characteristics of the sinter mix and the green bed permeability tests. The influence of the moisture content of the feed, granulation time, and mean granule diameter on permeability was investigated on Thabazimbi and Sishen iron ore, as well as on their mixture with fluxes and without fluxes. The iron ore results indicated that the mixture containing 20% Thabazimbi iron ore and 80% Sishen iron ore with fluxes where the coke, lime and return fines were sized by removing the – 0.5 mm size fraction of the return fines and coke, and the 1 mm size fraction of lime has the highest permeability of all the studied mixtures. The sintering properties of the mixtures of optimised grain size distributions were also investigated and the results were very similar for all the mixtures and better than the base case mixture, which was not optimised with respect to grain size distribution. / Dissertation (MEng)--University of Pretoria, 2008. / Materials Science and Metallurgical Engineering / unrestricted

The fluid bed granulation is a well-established method how to improve such properties of powders as flowability and increase content uniformity of the tablets. In this thesis, there was evaluated a granulation process on a lab scale fluid Glatt bed granulator and optimized for highest possible yield. Product yield in the size range of 80-90 % of granules and process reproducibility were stated as most effective. The product was analysed for its particle size distribution, the API distribution within the different particle size fractions and the flowability of the final granules. For process optimization, the most critical parameters such as spraying rate, particle size of raw materials and fluid bed pressure were identified and evaluated. As the highest-yielding dosage for the powder binder was found the spraying rate of 9 g/min. Changes in bed fluid pressure and nozzle pressure showed no significant improvement. Different grades of caffeine were compared for their impact on the granulation properties. Sieved caffeine enhanced yield of the product and reproducibility compared to bulk or disagglomerated caffeine.

Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 min in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present a model of random hot spots that generate a localized flux excess that perturbs the Cepheid light curve and consequently the pulsation period, which is consistent with the observed jitter. This result demonstrates how important understanding convection is for modeling Cepheid stellar structure and evolution, how convection determines the red edge of the instability strip, and just how sensitive Cepheid light curves are to atmospheric physics.

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.

A novel method for manufacturing granules with a large particle at their core, referred to as seeded granules, is presented. As an example, calcium carbonate powders (Durcal) of different grades are used as primary particles and polyethylene glycol (PEG) as liquid binder in high shear granulators of different scales (Cyclomix, manufactured by Hosokawa Micron B.V., The Netherlands). The conditions giving rise to seeded granulations are specified in the form of an operational regime map. It is found that the seeded structure is strongly dependent on the impeller speed and the primary particles size distribution. It is shown that a Stokes number of around 0.1 represents the optimal dynamic conditions in the given example for producing seeded granules, regardless of the scale of the granulator.

The effect of the operating conditions of three continuous high shear granulators on the internal structure and strength of granules has been investigated and the possibility of seeded granulation has been explored. In a recently concluded programme of research on the scale-up of a high shear granulator, Cyclomix (manufactured by Hosokawa Micron B.V., The Netherlands), a novel method of granulation called seeded granulation was introduced, where each granule contained, at its core, a large particle from the upper tail end of the feed particle size distribution. Seeded granulation is particularly useful for process control of continuous granulators as there is the potential to control granulation by the flow rate of the seed particles. Hence, the performance of three different types of continuous granulators in terms of granule strength and structure has been evaluated here; these are Extrudomix, Modulomix (manufactured by Hosokawa Micron, UK and The Netherlands, respectively) and the Nica M6 Turbine continuous granulator (manufactured by GEA, UK). Calcium carbonate (Durcal 65) powder was granulated using an aqueous solution of polyethylene glycol (PEG) as binder in the same ratio as used previously in our batch granulation, to allow comparison between the continuous and batch processes. The crushing strength was characterised by quasi-static side crushing between two platens using a mechanical testing machine. The internal structure and morphology were evaluated by scanning electron microscopy and the extent of seeding quantified. Granules produced in all the three continuous granulators were significantly weaker than those of the batch granulator tested previously. Among the continuous granulators only the Modulomix granulator produced some seeded granules. It is considered that longer residence time is necessary to produce seeded granules.

Yes / In the pharmaceutical industry, enhanced process understanding resulting in superior control of product attributes, has the potential to save up to 20% of process engineering and product development costs during drug development. With the aim of achieving enhanced process understating, a novel approach for granulation of fine powders is presented. First, a mould with the desired particle shape and size is created using 3D printing followed by casting using elastomeric material. The formulation is prepared through wet massing and tested as a thin film on flat elastomeric membranes. The thin film itself can be a product but it also gives a good indication of coating performance before coating the patterned elastic membrane with the formulation i.e., 3D printed elastic mould granulation. Results show that following granulation and drying, granules of controlled size and shape (e.g. cubic and 500 μm), strength, friability and flowability can be formed. The method presented may allow for more robust process development in particle engineering. / Research Development Fund Publication Prize Award winner, December 2018.

Damage to our tissues occurs daily and must be repaired by the body in a timely manner in order to prevent infection and restore tissue integrity. Many cell types are involved in the healing process, but it is the cells of the stroma that are largely responsible for rebuilding fibrous tissue, which provides structure and support for all other cell types during healing. This dissertation focuses on stromal tissue repair, the rebuilding of fibrous tissue by fibroblasts following injury. Specifically, I focus on 1) models to study wound healing in vitro, and the specific biological processes of healing that each model captures, 2) the response of engineered stromal microtissues to different methods of injury, namely laceration and laser ablation, and the subsequent clearance and rebuilding of the extracellular matrix by fibroblasts, and 3) how different types of stromal cells and extracellular matrix proteins contribute to tissue repair in vitro.