This dissertation investigates the flow physics, turbulence structure, and particle classification process in hydrocyclones using large-eddy simulations of turbulent multiphase flow. Two types of hydrocyclones are considered. The first is a classifying hydrocyclone, and the second is a mineral flotation hydrocyclone, also known as an air-sparged hydrocyclone (ASH). Large-eddy simulations (LES) are conducted for multi-phase flow (air, water, and sand particles) so that the complex anisotropic turbulence of a swirling flow is computed correctly. The effects of mesh refinements on the mean flow and turbulence stresses are investigated, and (LES) results are validated by comparisons with experimental data for classifying hydrocyclone. The two-phase flow in air-sparged hydrocyclone has not been analyzed before. ANSYS CFX software V17.2 has been used to conduct the simulations. Firstly, large-eddy simulations have been conducted for two-phase flow (water and air) in a conventional hydrocyclone using the Eulerian two-fluid (Eulerian-Eulerian) and Volume-of- Fluid (VOF) models. Subgrid stresses are modeled using a dynamic eddy–viscosity model, and results are compared to those using the Smagorinsky model. The effects of grid resolutions on the mean flow and turbulence statistics have been thoroughly investigated. Five block-structured grids of 0.72, 1.47, 2.4, 3.81, and 7.38 million elements have been used for the simulations of a typical conventional hydrocyclone designed and tested by Hsieh (75 mm hydrocyclone) [1]. Mean velocity profiles and normal Reynolds stresses have been compared with experimental data. The results of the Eulerian two-fluid model agree with those of the VOF model. A fine mesh in the axial and radial directions is necessary for capturing the turbulent vortical structures. Turbulence structures in the hydrocyclone are dominated by helical vortices around the air core. Energy spectra are analyzed at different points in the hydrocyclone, and regions of low turbulent kinetic energy are identified and attributed to stabilizing effects of the swirling velocity component. Turbulent energy spectra in the different regions of the hydrocyclone have been analyzed. The energy spectra are calculated at two points near the air-water interface. They show a short inertial subrange where energy decays as f−5/3, followed by viscous damping where energy drops as f−7, where f is frequency. However, for the points located near the boundary where high turbulent kinetic energy is found, the energy spectra exhibit f^(−4) decay. Secondly, the two-fluid (Eulerian two-fluid) model and large-eddy simulation are used to compute the turbulent two-phase flow of air and water in a cyclonic flotation device known as an Air-Sparged Hydrocyclone (ASH). In the operation of ASH, the air is injected through a porous cylindrical wall. The study considers a 48-mm diameter hydrocyclone and uses a block-structured fine mesh of 10.5 million hexahedral elements. The air-to-water injection ratio is 4, and a uniform air bubble diameter of 0.5 mm has been specified. The flow field in ASH has been investigated for the inlet flow rate of water of 30.6 L/min at different values of underflow exit pressure. The present simulations show that the value of static pressure imposed at the underflow section strongly affects the distribution of air volume fraction, water axial velocity, tangential velocity, and swirling layer thickness in ASH. The loci of zero-axial velocity surfaces have been determined for different exit pressures. The water split ratio through the overflow opening varies with underflow exit pressure as 6%, 8%, 16%, and 26% for 3, 4, 5, and 6 kPa, respectively. These results indicate that regulating the pressure at the underflow exit can be used to optimize ASH's performance. Turbulent energy spectra in different regions of the hydrocyclone have been analyzed. Small-scale turbulence spectra at near-wall points exhibit f^(−4) law, where f is frequency. Whereas for points at the air-column interface, the energy spectra show an inertial subrange f^(−5/3) followed by a dissipative range of f^(−7) law. Thirdly, large-eddy simulation (LES) has been used to investigate the flow separation in multi-phase flow (gas, liquid, and solid) in a classifying hydrocyclone using the multi-fluid (Eulerian multi-fluid) model. The results of the CFD simulation are compared with the Hsieh [1] experimental data. The water phase is considered a continuous phase, while air and solid particles are considered dispersed phases. Drag between water-air and water-sand is the only considered interfacial force. The Schiller-Naumann and Wen-Yu models are used to model the drag, and the Gidaspow model is used to calculate the solid pressure term. Various particle sizes are tested in the hydrocyclone to investigate the underflow recovery percentages. The results agree with the experimental data for the particles of a diameter smaller than 20 μm, while the results vary based on the model for the large particles. Therefore, using the Wen Yu and Schiller-Naumann model for the drag model and the Gidaspow model for the solid pressure in the three-fluid model could give acceptable results for the small particles underflow recovery and volume fraction distribution. However, the models failed for large particles. Finally, the large particle size separation needs more investigation. / Doctor of Philosophy / Hydrocyclones are widely used in mining and chemical industries. They can be used as separation devices to separate solid or fluid particles based on their size or/and weight. They can also be used as flotation devices to capture certain mineral particles from a slurry of water and solid particles. The flow field within a hydrocyclone is complex as it involves flow of different phases of matter (liquid, gas, and solid). It is also a turbulent flow in which the velocity and pressure fluctuate in time with many frequencies. The efficiency of the hydrocyclone depends on its geometry and distribution of the velocity. Computer simulations are very efficient tools to predict and study the flow field in hydrocyclones. This dissertation used a computer simulations to explain how turbulence could affect the particle separation from the slurry inside the hydrocyclones. The water's velocity fields, swirling flow, air behavior, pressure distribution and turbulence statistics are analysed. Understanding the turbulence structure and statistics in hydrocyclones is important for particle tracking and dispersion. Also, turbulent structure affects the motion of the air bubbles and solid particles in the flow field, which eventually will affect the hydrocyclone's performance. In short, a more comprehensive understanding of the behavior of turbulence of hydrocyclones represents an important tool that can guide the design of hydrocyclones according to their use goals and will help engineers who model these processes to develop a better model.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Hydrocyclones are separation devices that are widely used throughout the chemical engineering and mineral processing industries. Although simple in design, the intricate flow structure of the device complicates control. As an alternative to conventional empirical and theoretical modelling, process state monitoring methods have recently been employed as a means to control hydrocyclones. The purpose of process state monitoring methods is to distinguish between the desired operating state with favourable separation, the transition state, and the troublesome operating state of dense flow separation. In comparison to previously employed monitoring techniques, image analysis of the underflow is regarded as a promising approach. Preliminary studies have indicated that the technique complies with hydrocyclone monitoring requirements: sensitivity, non-invasiveness, sampling times less than one second, robustness and low cost. The primary objective of this study was therefore defined as investigating the feasibility of image analysis of hydrocyclone underflow as a monitoring technique. Data collection entailed the recording of hydrocyclone underflow for different operating states. Six case studies were performed in total: Gold, Ilmenite, Platreef, Merensky 1, Merensky 2 and Merensky 3 (with the case study names indicating the different ore types used). An image analysis technique, consisting of feature extraction through motion detection, as well as various noise reduction methods, was consequently developed and applied to the video data. Classification of the various operating states was attempted by performing modelling by one-class support vector machines (SVM). Results indicated that the developed image analysis technique effectively addresses background noise, random noise and system vibration through image enhancement and a motion threshold. Extremely low contrast differences and foreground noise did, however, prove problematic in Ilmenite and Merensky 1 case studies respectively. For the remaining case studies, it was found that the various operating states were identified with high accuracy through one-class SVM classification. This is particularly true for the identification of the troublesome dense flow separation for which extremely low missing alarm rates were obtained (0 % in most cases). In terms of practicality, the technique proved to be sensitive, non-intrusive and economical. The sampling time of 30 frames per second and estimated processing to video time ratio of 1:1, is furthermore satisfactory. Ultimately, the results indicate that the image analysis of hydrocyclone underflow is a viable monitoring technique. The robustness of the technique might further be improved by use of backlighting and an air-knife. It is also recommended that future work should focus on testing the monitoring technique on an industrial hydrocyclone setup. / AFRIKAANSE OPSOMMING: Hidrosiklone is skeidingsapparate wat algemeen gebruik word in chemiese ingenieurswese en mineraalprosesserings industrieë. Alhoewel die apparaat ‘n eenvoudige ontwerp het, bemoeilik die komplekse interne vloeistruktuur die beheer daarvan. Prosestoestandmoniteringsmetodes is vir hidrosikloonbeheer toegepas as alternatief vir konvensionele empiriese en teoretiese modellering. Die doel van prosestoestandmoniteringsmetodes is om te onderskei tussen die gewenste bedryfstoestand met gunstige skeiding, die oorgangstoestand, en die moeilike bedryfstoestand van digtevloeiskeiding. In vergelyking met vorige toegepaste moniteringstegnieke, word beeldverwerking van die ondervloei beskou as ‘n belowende tegniek. Voorlopige studies het aangedui dat die tegniek voldoen aan die hidrosikloonmoniteringvereistes: sensitiwiteit, nie-indringendheid, monsternemingstydperke laer as een sekonde, robuustheid en lae koste. Die primêre doelwit van hierdie studie is daarom gedefineer as die ondersoek van die doenlikheid van beeldverwerking van hidrosikloon ondervloei as ‘n moniteringstegniek. Die data versameling het die afneem van hidrosikloon ondervloei vir verskillende bedryfstoestande behels. Ses gevallestudies is in totaal uitgevoer: Goud, Ilmeniet, Platreef, Merensky 1, Merensky 2 en Merensky 3 (die gevallestudie name dui die verskillende erts tipes wat gebruik is aan). ‘n Beeldverwerkingstegniek, wat bestaan uit kenmerkekstraksie deur bewegingsopsporing, asook verskeie geruisverlagingsmetodes, is gevolglik ontwikkel en toegepas op die video data. Klassifikasie van die verskeie bedryfstoestande is beproef deur modellering met enkelklassteunvektormasjiene. Resultate het aangedui dat die ontwikkelde beeldverwerkingstegniek agtergrond geruis, onreëlmatige geruis en sisteem vibrasie suksesvol aanspreek deur beeldversterking en ‘n bewegingslimiet. Beduidende lae kontrasverskille en voorgrond geruis blyk wel problematies in die Ilmeniet en Merensky 1 gevallestudies onderskeidelik. Vir die orige gevallestudies is gevind dat die verskillinde bedryfstoestande met hoë akkuraatheid geïdentifiseer is deur enkelklassteunvektormasjiene klassifisering. Dit is veral waar vir die identifisering van die moeilike digtevloeiskeiding waarvoor beduidende lae vermiste-alarmmaatstawwe behaal is (0 % in die meeste gevalle). Aangaande die praktiese aspekte, blyk die tegniek sensitief, nie-indringend en ekonomies. Die monsternemingstydperk van 30 raampies per sekonde en die beraamde prosesserings- tot videotyd verhouding van 1:1, is ook voldoende. Ten slotte dui die resultate daarop dat die beeldverwerking van hidrosikloon ondervloei ‘n uitvoerbare moniteringstegniek is. Die robuustheid van die tegniek sou verder verbeter kon word deur gebruik te maak van agtergrondverligting en ‘n lugspuit. Dit word ook aanbeveel dat toekomstige werk op die toetsing van die moniteringstegniek op ‘n industriële hidrosikloon toestel moet fokus.

In the fermentation process for ethanol production, the yeast Saccharomyces cerevisiae are recovered and recycled to a new stage of fermentation. This separation process is a major challenge, because the yeasts are small and low density. For this purpose the hydrocyclone emerges as an interesting alternative, because it uses the same principle of centrifugal separation, requires low maintenance and can be readily sterilized. This study aimed to optimize the separation process of yeast fermentation using hydrocyclones. To this end, was evaluated through experimental studies the influence of geometric and operational variables on the performance of hydrocyclones. A factorial experimental design (34) was applied and the results were used for the determination of empirical mathematical models that describe the capacity, total efficiency of separation, the flow ratio and reduced separation efficiency as a function of different geometric variables (feed inlet diameter, overflow diameter and angle of the hydrocyclone cone) and pressure drop. The geometry "optimum" founded was used in another factorial experimental design which aimed at evaluating the effect of concentration and pressure drop on the performance of the hydrocyclone. The diameters of the feed and overflow pipes studied were 2, 3 and 4 mm, while the angles of the hydrocyclone cone ranged from 6, 8 and 10º. The tests were conducted with suspensions of yeast in water with yeast concentrations from 0.5% to 5.5% by mass. All tests were performed at three different pressure drops (15, 23 and 31 psi). For yeast concentration of 1% was obtained total efficiencies of separation between 36.54 to 92.02%, reduced separation efficiencies from 4.67 to 55.59%, capacities from 0.1183 to 0.4579 m3/h and flow ratios, ranging from 31.74 to 84.30%. It also investigated the centrifugal forces generated within these devices ranging from 291g to 4153g. Analysis and discussion of the results show that the reduction of geometric variables with the increase in pressure drop and use of less concentrated suspensions led, in general, to an increase in total efficiency of separation. For the largest pressure drop conditions, the reduction of viability was checked and presented values below 6.76%. CFD techniques have also been applied in order to simulate the internal flow of a hydrocyclone. / No processo de fermentação para produção de etanol, as leveduras de Saccharomyces cerevisiae são recuperadas e recicladas para uma nova etapa de fermentação. Este processo de separação representa um grande desafio, pois as leveduras são pequenas e com baixa densidade. Para tal finalidade, o hidrociclone surge como uma alternativa interessante pois, além de utilizar o mesmo princípio de separação das centrífugas, requer baixo custo de manutenção e pode ser prontamente esterilizado. O presente trabalho teve como objetivo otimizar o processo de separação de leveduras da fermentação alcoólica utilizando hidrociclones. Para tanto, avaliou-se, através de estudos experimentais, a influência de variáveis geométricas e operacionais sobre o desempenho de hidrociclones. Um planejamento experimental fatorial (34) foi empregado e os resultados foram usados para a determinação de modelos matemáticos empíricos que descrevem a capacidade, eficiência total, a razão de líquido e a eficiência total reduzida como função de diferentes variáveis geométricas (diâmetro da alimentação, diâmetro do overflow e ângulo de tronco de cone) e da queda de pressão. A geometria ótima encontrada foi utilizada em um outro planejamento 3 níveis que visava avaliar o efeito da concentração e da queda de pressão sobre o desempenho deste hidrociclone. Os diâmetros dos dutos de alimentação e overflow estudados foram de 2, 3 e 4 mm, enquanto que os ângulos de tronco de cone analisados foram de 6, 8 e 10º. Os ensaios foram conduzidos com suspensões de leveduras em água, com concentrações de leveduras de 0,5% a 5,5% em massa. Todos os testes foram realizados a três diferentes quedas de pressão (15, 23 e 31 psi). Para uma concentração de leveduras de 1%, foram obtidas eficiências totais de separação entre 36,54 a 92,02%, eficiências totais reduzidas de 4,67 a 55,59%, capacidades de 0,1183 a 0,4579 m3/h e razões de líquido com valores entre 31,74 a 84,30%. Investigaramse também as forças centrífugas geradas no interior destes equipamentos que variaram de 291g a 4153g. Da análise e discussão dos resultados, pôde-se identificar que a diminuição das variáveis geométricas junto ao aumento na queda de pressão e utilização de suspensões menos concentradas levou, de um modo geral, a um aumento na eficiência total de separação. Para as maiores condições de queda de pressão foram verificadas as quedas de viabilidade que se situaram abaixo de 6,76%. Técnicas de CFD também foram aplicadas no intuito de simular o escoamento interno de um hidrociclone. / Mestre em Engenharia Química

Microfibers, textile fibres shorter than 5 mm, and are shed from fabrics during wear and released into the laundry effluent during washing. When passed through the wastewater treatment plant (WWTP), they adsorb toxins, heavy metals and pathogens before being released into the environment. Synthetic microfibers persist for long periods of time in aquatic environments and very little is known about the degradation of processed natural fibres. Hydrocyclonic separation was studied as a way to separate the microfibers from the effluent before being they get additionally contaminated at the WWTP. A hydrocyclone has no moving parts and functions by utilizing centrifugal force and the difference in specific gravity between the fluid and the particles that are to be separated. The separation efficiency is dependent on its dimensional and operation parameters. No previous studies on hydrocyclonic separation of microfibres were found. Polyester fleece blankets were washed. The effluent was filtered, and the filters weighed to determine the mass of the separated fibres. Sampling of the inhomogeneous effluent presented a challenge and larger sample volumes would be needed to adequately represent the population. Using a Büchner funnel, filter fouling led to filtration times of up to 6 h for 1 l of effluent. Dividing the 1 l samples into two 0.5 l samples, filtering separately and adding the weight reduced filtration time to 2 h and the results were not significantly different from filtering the whole 1 l sample with one filter. The hydrocyclones tested separated around 11% of the total weight of microfibers in the effluent, too low to be deemed viable. As only a few dimensional variables were tested, it could possible that a higher fraction could be separated with this method. Given that the commercially available filtration systems separate 30-80%, refining existing methods may yield better results.

Both Part I and Part II are included. / The separation of a mixture of glass spheres in water using 2 inch hydrocyclones was studied. <p> Three operating parameters were investigated: feed concentration, volume split and feed flow rate. In addition, three design parameters were cone angle, inlet diameter, and vortex finder length. The performance criterion parameters were the efficiency with which the solids were separated from the liquid, and the energy required per unit mass flowing through the hydrocyclone. </p> <p> First the experimental data were analyzed by three different statistical methods and the results compared in an attempt to determine which statistical method was most suitable for this two criteria system. The three methods were principal component analysis, canonical correlation analysis and multiple regression analysis. The theory behind these methods is briefly outlined. Our conclusion is that using all three methods give much more insight than could be obtained from any individual method. </p> <p> Second, an analysis of the above eight hydrocyclonc parameters of hydrocyclones with cylindrical sections indicated that for the range of parameters covered in this work, feed flow rate and inlet diameter influenced the energy loss most; volume split influenced the separation efficiency the most. Energy loss and separation efficiency are quite independent; this means that it is possible to design and run a hydrocyclone with high separation efficiency and low energy loss. The dilute concentrations used in this work indicate that a hydrocyclone of conventional design can be used in waste water treatment. When the parameters were correlated, a power model gave more consistent interpretation than a linear model. </p> <p> Third, the effect of the three operating parameters on hydrocyclones with three different body shapes suggested that the most efficient cyclone was one with a straight cone and no cylindrical section. The body shape dictated which parameters would significantly affect performance. </p> / Thesis / Master of Engineering (ME)

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Hydrocyclones are stationary separating machines that separate materials based on centrifugal separation and are widely used in chemical engineering and mineral processing industries. Their design and operation, compact structure, low running costs and versatility all contribute to their applications in liquid clarification, slurry thickening, solid washing and classification. With any of these operations, the overall profitability of the process relies on the effective control of the process equipment. However, in practice, hydrocyclones are difficult to monitor and control, owing to the complexity and difficulty in measuring internal flows in the equipment. Several studies have indicated that hydrocyclone underflow images can be used to monitor process conditions. The research described in this thesis considers the use of image analysis to monitor particle size and solids concentration in the underflow discharge of a hydrocyclone. The experimental work consisted of laboratory and industrial-based case studies. The laboratory cyclone used was a 76 mm general laboratory cyclone. A Canon EOS 400D digital camera was used for the underflow imaging. Image features such as pixel intensity values, underflow discharge width and grey level co-occurrence matrix (GLCM) were extracted from the images using MATLAB Toolbox software. Linear discriminant analysis (LDA) and neural network (NN) classification models were used to discriminate between different PGM ore types based on features extracted from the underflow of the hydrocyclone. Likewise, multiple linear regression and neural network models were used to estimate the underflow solids content and mean particle size in the hydrocyclone underflow. The LDA model could predict the PGM ore types with 61% reliability, while the NN model could do so with a statistically similar 62% reliability. The multiple linear regression models could explain 56% and 40% of variance in the mean particle size and solids content respectively. In contrast, the neural network model could explain 67% and 45% of the variance of the mean particle size and solids content respectively. For the industrial system, a 100% correct classification was achieved with all methods. However, these results are regarded as unreliable, owing to the insufficient data used in the models. / AFRIKAANSE OPSOMMING: Hidrosiklone is stasionêre skeidingsmasjiene wat materiale skei op grond van sentrifugale skeiding en word algemeen gebruik in die chemiese ingenieurswese en mineraalprosessering industrieë. Hul ontwerp en werking, kompakte struktuur, lae bedryfskoste en veelsydigheid dra by tot hul gebruik vir toepassings in vloeistofsuiwering, slykverdikking, vastestof wassing en klassifikasie. In enige van hierdie prosesse hang die oorhoofse winsgewendheid van die proses af van die effektiewe beheer van die prosestoerusting. In die praktyk is hidrosiklone egter moeilik om te monitor en beheer weens die kompleksiteit en moeilikheidsgraad daarvan om die interne vloei in die apparaat te meet. Verskeie studies het aangedui dat hidrosikloon ondervloeibeelde gebruik kan word om die proseskondisies te monitor. Die navorsing beskryf in hierdie tesis maak gebruik van beeldanalise moniteringstegnieke om die ertstipes en grootte- verspreidingsgebiede/ klasse van die ondervloei afvoerpartikels te bepaal. Sodoende word ‘n grondslag gelê vir verbeterde sikloon monitering en beheer. Die eksperimentele werk het bestaan uit beide laboratorium en industrieel-gebaseerde studies. Die laboratorium sikloon wat gebruik is, was ‘n 76 mm algemene laboratorium sikloon. ‘n Canon EOS 400D digitale kamera is gebruik om die hidrosikloon ondervloei beelde vas te vang. Beeldeienskappe soos beeldelement intensiteitswaardes, ondervloei afvoerwydte en grysvlak mede-voorkoms matriks is onttrek uit die beelde deur gebruik te maak van MATLAB Toolbox sagteware. Lineêre diskriminantanalise (LDA) en neural netwerk (NN) klassifikasiemodelle is gebou om te onderskei tussen die verskillende PGM ertse en gebaseer op veranderlikes wat afgelei is uit beelde van die ondervloei van die sikloon. Net so is daar ook gebruik gemaak van lineêre regressie- en neural netwerkmodelle om die vasestofkonsentrasie en gemiddelde partikelgrootte in die ondervloei van die sikloon te beraam. Die LDA model kon die PGM ertstipes met 61% betroubaarheid voorspel, terwyl die neural netwerkmodel dit kon doen met statisties dieselfde betroubaarheid van 62%. Die lineêre regressiemodelle kon onderskeidelik 56% en 40% van die variansie in die gemiddelde partikelgrootte en vastestofkonsentrasie verduidelik. In teenstelling iermee, kon die neurale netwerkmodel 67% en 45% van die variansie in die gemiddelde partikelgrootte en vastestofkonsentrasie verduidelik. In die nywerheidstelsel kon beide tipe modelle perfekte onderskeid tref tussen die partikelgroottes wat gemeet is op opeenvolgende dae van die bedryf van die siklone. Hierdie resultate is egter nie betroubaar nie, a.g.v. die beperkte hoeveelheid data wat beskikbaar was vir modellering.

Submitted by Andrea Pereira (andrea.pereira@unipampa.edu.br) on 2017-03-13T17:19:12Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertacao_artur_mestrado_engenharia.pdf: 3325844 bytes, checksum: b863f8afcb5e72944fca004924293530 (MD5) / Approved for entry into archive by Andrea Pereira (andrea.pereira@unipampa.edu.br) on 2017-03-13T17:20:18Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertacao_artur_mestrado_engenharia.pdf: 3325844 bytes, checksum: b863f8afcb5e72944fca004924293530 (MD5) / Made available in DSpace on 2017-03-13T17:20:18Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertacao_artur_mestrado_engenharia.pdf: 3325844 bytes, checksum: b863f8afcb5e72944fca004924293530 (MD5) Previous issue date: 2015-12-03 / O descarte de efluentes industriais e residenciais em corpos hídricos ganha cada vez mais atenção da fiscalização dos órgãos ambientais. Assim, é crescente a contribuição de grupos de pesquisas científicas em desenvolver novas tecnologias que contribuam para que esses descartes sejam menos prejudiciais à natureza. A indústria têxtil contribui com uma grande geração de poluentes que quando não são devidamente tratados se tornam agravante problema ambiental. Uma das matérias primas da indústria têxtil é a lã de ovinos. Devido às condições como são criadas as ovelhas, para o processamento industrial dessa lã é indispensável a retirada da maior parte possível de impurezas por meio da lavagem, para então ser transformada em fio pelo processo de cardar e por fim ser fiada e tingida. A alta temperatura e pH que são utilizados na lavagem contribuem significativamente para a geração dos lodos como efluente e a alta quantidade de água utilizada faz com que este efluente fique bastante úmido. O método mais comum de tratamento desse tipo de efluente se dá por meio da decantação ou sedimentação através de tratamento biológico via sistema de lodos ativados. Apesar de apresentar uma boa eficiência, esse método não é suficiente para remoção de compostos orgânicos dissolvidos, além de produzir grande volume de lodo. Algumas opções como a secagem ou hidrociclonagem, contribuem para o espessamento dos lodos gerados durante o tratamento do efluente. Os parâmetros geométricos dos hidrociclones dependem da família a qual ele pertence, as configurações da família Rietema e Bradley são os que aparecem com mais frequência nos trabalhos da literatura quando se trata de equipamentos com boa eficiência para separação de sólido-líquido. O Rio Grande do Sul, dentre os estados brasileiros, se destaca tanto na produção têxtil como no cenário da pecuária, em especial na produção de lãs de ovinos, por isso o objetivo desse trabalho foi projetar, analisar e simular a fluidodinâmica de hidrociclones do tipo Rietema e Bradley para o espessamento do lodo produzido por uma indústria têxtil da cidade de Bagé – RS. Primeiro, foi realizado a caracterização física do lodo do efluente através da obtenção da temperatura, da massa específica da fase fluida e da parte sólida, da sua viscosidade, da sua concentração de sólidos, e da sua distribuição do tamanho médio de partículas. Também foi feita a caracterização química através das medidas do pH, da DQO, da quantidade de matéria orgânica e condutividade elétrica. Com base nesses resultados e nas equações que relacionam a eficiência com diâmetro de corte e com o diâmetro da secção cilíndrica do hidrociclone, foi possível projetar e analisar o comportamento das eficiências dos hidrociclones de configuração Rietema e Bradley. Também foi verificado com base nas relações de Euler e Reynold qual dos hidrociclones tem menor gasto energético para uma mesma faixa de eficiência. Por fim, foi realizada a análise numérica por meio de simulação computacional, por CFD utilizando o programa ANSYS para descrever os perfis de velocidade, pressão e o comportamento da fase líquida e sólida no interior dos hidrociclones. Os resultados da caracterização física demostraram que o lodo possui massa específica de 1000,05 kg/m3 e o sólido contido no lodo possui uma massa específica de 1002,64 kg/m3 e diâmetro de partícula de 586 e uma concentração volumétrica de sólidos de 4,2 %. Na sensibilidade paramétrica, os hidrociclones de configuração Rietema e Bradley se comportaram de maneira bastante semelhante. Os resultados das simulações auxiliaram no conhecimento e na interpretação gráfica de como ocorre o movimento do fluido e a separação das fases no interior do hidrociclone. Na visualização dos perfis de velocidade tangencial, foi observado que esta é maior na região central do hidrociclone, onde retornará por movimento helicoidal ascendente, à fase menos densa. As correntes de pressão mostraram que essa variável é maior próxima nas paredes do hidrociclone, o que provoca a separação das fases. Para análise da eficiência foi utilizado o modelo Lagrangeano com curva de dispersões de sólido em água com mediana de distribuição de 586 . Ambos hidrociclones projetados apresentaram uma eficiência de separação de 74 %. / The disposal of industrial and residential wastewater into water bodies has gained increasing attention of surveillance of environmental agencies. So it is increasing the contribution of scientific research groups to develop new technologies to help ensure that these discharges are less harmful to nature. The textile industry contributes a great generation of pollutants that are not properly treated when they become aggravating environmental problem. One of the raw materials of the textile industry is the sheep wool. Due to the sheep conditions are created for the industrial processing of such wool is essential that the largest possible removal of impurities by washing, then to be transformed into yarn by carding process and finally be spun and dyed. The high temperature and pH which are used in the wash contribute significantly to the generation of effluent and sludge as high amount of water used makes this effluent becomes moist enough. The most common method of treatment of this effluent is through decantation or sedimentation through biological treatment through activated sludge system. Despite presenting a good efficiency, this method is not sufficient for removing dissolved organic compounds, besides being very susceptible to the effluent composition and produce large amounts of sludge. Some options like, drying or hydrocycloning, contribute to the thickening of sludges generated during treatment of the effluent. The geometric parameters of hydrocyclones depend on the family to which it belongs, Rietema and Bradley Family settings are appearing more frequently in the work of literature when it comes to equipment with good efficiency for solid-liquid separation. The Rio Grande do Sul, among the Brazilian states, it is so prominent in the textile production and in livestock scenario, especially in wool production of sheep, so the aim of this study was to design, analyze and simulate the fluid dynamics of hydrocyclones type Rietema and Bradley for sludge thickening produced by a textile city of Bage - RS. First the physical characterization was carried effluent sludge by raising the temperature, the density of the fluid phase and the solid part of its viscosity, its solids concentration and its distribution of the average particle size. Also the chemical characterization was done by raising the pH, COD, the amount of organic matter and conductivity. Based on these results and the equations that relate efficiency with cutting diameter and the diameter of the cylindrical section of the hydrocyclone, it was possible to design and analyze the behavior of the efficiencies of Rietema and Bradley configuration hydrocyclones. It also found based on the relationship of Euler and Reynold which the hydrocyclones has lower energy expenditure for the same range of efficiency. Finally, a numerical analysis was carried out through computer simulation by CFD ANSYS software to describe the velocity profile, pressure and performance of liquid and solid phase within the hydrocyclones. The results of the physical characterization showed that the sludge has a specific weight of 1000.05 kg / m3 and the solid contained in the sludge has a specific weight of 1002.64 kg / m3 and a particle diameter of 586 m and a volume concentration of 4 ,2 %. In parametric sensitivity, the configuration hydrocyclones Rietema and Bradley behaved in much the same way. The simulation results helped in knowledge and graphic interpretation of how occurs the fluid motion and phase separation inside the hydrocyclone. In view of the tangential velocity profiles, it was observed that this is higher in the central region of the hydrocyclone, which returns ascending helical movement, the less dense phase. The pressure currents shown that this variable is greater near the walls of the hydrocyclone, which causes phase separation. To analyze the efficiency we used the Lagrangian model with solid dispersions curve in water with a median of distribution of 586 micrometers. Both hydrocyclones designed showed a 74% separation efficiency.

The increase of the industrial pollution has been carrying the organs of environmental control to review the legislation in force and to limit in a more rigorous form the discards of industrial effluent. As opposed, the companies have been improving the treatment systems of their effluent, applying new technologies. In the petroleum industry, in the oil-water separation, are used floatation chamber and hydrocyclones. The floatation seeks to recover the oil residue through gravitational separation, while the hydrocyclones try to accelerate this process with the use of the centrifugal force. The hydrocyclones in study are equipment constituted of a cylindrical part and two conic parts joint, in which the supply is constituted by two entrances involute, diametrically opposite, presenting a normal axis to the equipment and positioned tangentially to the lateral wall of the cylinder. The separator has two openings for exit, axis positioned to the equipment, one of them, called overflow, placed near to the supply section and to another, called underflow, placed near to the vertex of the conic body of the hydrocyclone. The analysis of the fluid-dynamic behavior of the hydrocyclone was led through the numeric simulation of the treatment of water produced, applying methods of Computational Fluid-dynamic (CFD). In the used computational tool, CFX, it is possible to build the geometry, draw the numeric mesh, adjust the simulation parameters, solve and to analyze the results, being able to be applied for several kinds of flow. It accomplished an experimental planning with the goal of analyzing the influence of the geometry in the separation efficiency of the hydrocyclone, in other words, know which variables were more important for the separation efficiency. To evaluate the performance of the equipment were calculated the Flow Ratio (Rf) and the Reduced Grade Efficiency (G ), for each geometry. Due to the great number of tested variables, whatever Dc, Do, Du, Hc, VF e L1 it opted to not analyze the effect of each one in separated, but the interactions of these. The different numeric simulations were considered as computational experiments. In all the 19 computational experiments, the simulations were initiated with the turbulence model k-e, these last used as initial values for the simulations with the turbulence model SSG, because this last is what best represents the flow in the hydrocyclone. The analyses done in the Essential Regression show that the variables which the most influence the separation efficiency are the overflow and underflow diameters. The reduced grade efficiencies stayed well distributed in the range 0-96%, what shows that the choice of the size of tried drop (250 mm) was adequate. The greatest reason values of fluid were obtained for Do/Du @ 1.0 and the minors, excluding Rf = 0, for Do/Du @ 0.2. In the studied intervals, the greatest Reduced Grade Efficiency values are obtained with the biggest values of Do and the smallest of Du. The smallest results of Flow Ratio are obtained with the smallest values of Do and the biggest values of Du. / O aumento da poluição industrial tem levado os órgãos de controle ambiental a rever a legislação em vigor e a limitar de forma mais rigorosa o descarte de efluentes industriais. Em contrapartida, as empresas têm melhorado os sistemas de tratamento de seus efluentes, aplicando novas tecnologias. Na indústria de petróleo, na separação óleo-água, são usados flotadores e hidrociclones. A flotação procura recuperar o resíduo de óleo através de separação gravitacional, enquanto que os hidrociclones procuram acelerar este processo com o uso da força centrífuga. Os hidrociclones em estudo são equipamentos constituídos de uma parte cilíndrica e duas partes cônicas justapostas, nas quais a alimentação é constituída por duas entradas em voluta, diametralmente opostas, apresentando um eixo normal ao do equipamento e posicionada tangencialmente à parede lateral do cilindro. O separador tem duas aberturas para saída, posicionadas axialmente ao equipamento, uma delas, chamada overflow, situada próxima à seção de alimentação e a outra, chamada underflow, situada próxima ao vértice do corpo cônico do hidrociclone. A análise do comportamento fluidodinâmico do hidrociclone foi conduzida através da simulação numérica do tratamento da água produzida, aplicando-se métodos de Fluidodinâmica Computacional (CFD). Na ferramenta computacional utilizada, CFX, é possível construir a geometria, desenhar a malha numérica, ajustar os parâmetros de simulação, resolver e analisar os resultados, podendo ser aplicado para diversos tipos de escoamento. Realizou-se um planejamento experimental com o objetivo de analisar a influência da geometria na eficiência de separação do hidrociclone, ou seja, saber quais variáveis eram mais relevantes para a eficiência de separação. Para avaliar o desempenho do equipamento foram calculadas a Razão de Fluido (Rf) e a Eficiência Granulométrica Reduzida (G ), para cada geometria. Devido ao grande número de variáveis testadas, quais sejam Dc, Do, Du, Hc, VF e L1 optou-se por não analisar o efeito de cada uma em separado, mas a interações destas. As diferentes simulações numéricas foram consideradas como experimentos computacionais. Em todos os 19 experimentos computacionais, as simulações foram iniciadas com o modelo de turbulência k-, estas últimas utilizadas como valores iniciais para as simulações com o modelo de turbulência SSG, pois este último é o que melhor representa o escoamento no hidrociclone. As análises feitas no Essential Regression mostram que as variáveis que mais influenciam a eficiência de separação são os diâmetros de overflow e de underflow. As eficiências granulométricas reduzidas ficaram bem distribuídas na faixa 0-96%, o que mostra que a escolha do tamanho de gota testado (250 mm) foi adequada. Os maiores valores de razão de fluido foram obtidos para Do/Du @ 1,0 e os menores, excluindo-se Rf = 0, para Do/Du @ 0,2. Nos intervalos estudados, os maiores valores de Eficiência Granulométrica Reduzida são obtidos com os maiores valores de Do e os menores de Du. Os menores resultados de Razão de Fluido são obtidos com os menores valores de Do e os maiores valores de Du.

Abstract Plant fibres are an important part of modern daily life. The most obvious consumer products manufactured from them are paper, cardboard and the fibreboards used in the construction and furniture industries. Plants producing a woody stem are the most widely used raw materials for these fibre products but fibres originating from other plants, i.e. non-wood fibres, are used too. One of the most promising potential non-wood fibre resource categories is that of grasses, of which the cereals are the most important plants grown worldwide. A huge amount of straw is generated as an agricultural by-product annually, but the amount used as an industrial raw material is low because it contains components that are detrimental either to processability or to product quality. The purpose of pulp fractionation is to divide pulp into fractions with distinct properties. Industrially feasible fractionation methods are pressure screening, hydrocyclone fractionation and flotation. In pressure screening, separation is based on a mechanical barrier and particles are fractionated according to their dimensions, while a hydrocyclone fractionates particles according to their density and specific surface area and flotation fractionates particles according to their surface chemistry. These methods are traditionally used for removing impurities from pulp but numerous reports on pulp fractionation can also be found. Previous fractionation experiments were performed using wood-based pulps, whereas no previous studies are available concerning the fractionation of pulps manufactured using grasses. The aim of the present work was to determine whether it is possible to fractionate wheat straw pulp by methods that are feasible on an industrial scale. The experimental part was concerned with wheat straw pulp fractionation by pressure screening, hydrocyclone fractionation and flotation. The results show that all these fractionation methods were able to divide the wheat straw pulp into fractions with different cell properties and cell types, e.g. distinct cell lengths, cell wall thicknesses or surface chemistries. Likewise, fractionation can be used to remove detrimental components or to optimize pulp properties according to their end use or to optimize pulp processing sequences. Due to the uniform structure of grasses, it is likely that the results can be generalized to other grasses than that employed here. / Tiivistelmä Kasvisoluja sisältävät tuotteet ovat laajalti mukana ihmisten jokapäiväisessä elämässä. Kaikista näkyvimpiä tuotteita ovat paperi- ja kartonkituotteet sekä rakennus- ja huonekaluteollisuuden käyttämät kuitulevyt. Perinteisesti kasvikuidut näihin tuotteisiin on saatu puuvartisista kasveista, mutta raaka-aineena käytetään muitakin kasveja, niin kutsuttuja non-wood kasveja. Yksi potentiaalinen kasviryhmä teollisuuden raaka-aineeksi ovat heinäkasvit. Muun muassa tärkeimmät viljakasvit ovat heinäkasveja, ja maatalouden sivutuotteina syntyy korsimateriaalia maailmanlaajuisesti huomattava määrä. Heinäkasvien teollinen hyödyntäminen on kuitenkin vähäistä sillä ne sisältävät komponentteja, jotka haittaavat materiaalin prosessointia tai ovat lopputuotteen ominaisuuksia heikentäviä. Kuitususpension fraktioinnin tarkoituksena on jakaa suspensio kahteen tai useampaan jakeeseen, joiden kuituominaisuudet tai solukoostumus ovat erilaiset. Teollisesti käytettävissä olevia fraktiointilaitteita ovat painelajitin, hydrosykloni ja flotaatio: painelajittimessa erottuminen perustuu mekaaniseen esteeseen ja partikkelit erottuvat pääasiassa partikkelin dimensioiden perusteella, hydrosyklonissa erottuminen tapahtuu partikkelien tiheyden ja ominaispinta-alan mukaan kun taas flotaatiolla voidaan erottaa pintakemialtaan erilaisia partikkeleita. Näitä laitteita on perinteisesti käytetty epäpuhtauksien poistamiseen kuitususpensiosta, mutta laitteiden käyttöä puusta valmistettujen massojen fraktiointiin on tutkittu laajasti. Heinäkasveista valmistettujen massojen fraktiointiin näitä menetelmiä ei ole sovellettu. Tämän tutkimuksen tarkoituksena oli selvittää vehnämassan sisältämien solujen fraktiointia teollisuuden käyttöön soveltuvilla menetelmillä. Työn kokeellisessa osassa fraktiointiin vehnäsellua painelajittimella, hydrosyklonilla ja flotaatiolla. Työn tulokset osoittavat, että kaikki tutkitut fraktiointimenetelmät pystyvät jakamaan vehnämassan jakeisiin, joilla on erilaiset solujen ominaisuudet sekä solukoostumukset. Fraktioinnin avulla on mahdollista tuottaa jakeita, joiden kuitupituudet, seinämäpaksuudet sekä pintakemia eroavat. Näin ollen massasta voidaan poistaa jokin haitallinen solujae, tai vaihtoehtoisesti fraktiointia voidaan käyttää optimoitaessa massan ominaisuuksia lopputuotteen ominaisuuksien parantamiseksi, tai optimoitaessa massan prosessointia. Koska heinäkasvit ovat rakenteeltaan samanlaisia, ovat tulokset hyvin todennäköisesti yleistettävissä muidenkin heinäkasvien fraktiointiin.

<p>This thesis presents a method of measuring the distribution of fiber bonding ability in mechanical pulp furnishes. The method is intended for industrial use, where today only average values are used to describe fiber bonding ability, despite the differences in morphology of the fibers entering the mill. Fiber bonding ability in this paper refers to the mechanical fiber’s flexibility and ability to form large contact areas to other fibers, characteristics required for good paper surfaces and strength.</p><p> </p><p>Five mechanical pulps (Pulps A-E), all produced in different processes from Norway spruce (<em>Picea Abies)</em> were fractionated in hydrocyclones with respect to the fiber bonding ability. Five streams were formed from the hydrocyclone fractionation, Streams 1-5. Each stream plus the feed (Stream 0) was fractionated according to fiber length in a Bauer McNett classifier to compare the fibers at equal fiber lengths (Bauer McNett screens 16, 30, 50, and 100 mesh were used).</p><p> </p><p>Stream 1 was found to have the highest fiber bonding ability, evaluated as tensile strength and apparent density of long fiber laboratory sheets. External fibrillation and collapse resistance index measured in FiberLab^TM, an optical measurement device, also showed this result. Stream 5 was found to have the lowest fiber bonding ability, with a consecutively falling scale between Stream 1 and Stream 5. The results from acoustic emission measurements and cross-sectional scanning electron microscopy analysis concluded the same pattern. The amount of fibers in each hydrocyclone stream was also regarded as a measure of the fibers’ bonding ability in each pulp.</p><p> </p><p>The equation for predicted Bonding Indicator (BIN) was calculated by combining, through linear regression, the collapse resistance index and external fibrillation of the P16/R30 fractions for Pulps A and B. Predicted Bonding Indicator was found to correlate well with measured tensile strength. The BIN-equation was then applied also to the data for Pulps C-E, P16/R30, and Pulp A-E, P30/R50, and predicted Bonding Indicator showed good correlations with tensile strength also for these fibers.</p><p> </p><p>From the fiber raw data measured by the FiberLab^TM instrument, the BIN-equation was used for each individual fiber. This made it possible to calculate a BIN-distribution of the fibers, that is, a distribution of fiber bonding ability.</p><p> </p><p>The thesis also shows how the BIN-distributions of fibers can be derived from FiberLab^TM measurements of the entire pulp without mechanically separating the fibers by length first, for example in a Bauer McNett classifier. This is of great importance, as the method is intended for industrial use, and possibly as an online-method. Hopefully, the BIN-method will become a useful tool for process evaluations and optimizations in the future.</p> / <p>Den här studien presenterar en metod för att mäta fördelning av fiberbindning i mekaniska massor. Metoden hoppas kunna användas industriellt, där i dagsläget enbart medelvärden används för att mäta fiberbindnings-fördelning, trots råvarans (fibrernas) morfologiska skillnader.</p><p> </p><p>Fem mekaniska massor (Massa A-E) från olika massaprocesser men från samma råvara, norsk gran (<em>Picea Abies</em>), har fraktionerats i hydrocykloner med avseende på fiberbindningsförmåga. Från hydrocyklon-fraktioneringen bildades fem strömmar, Ström 1-5. Varje ström plus injektet (Ström 0) fraktionerades också med avseende på fiberlängd i en Bauer McNett för att kunna jämföra fibrerna vid samma fiberlängd (Bauer McNett silplåtarna 16, 30, 50 och 100 mesh användes).</p><p> </p><p>Fiberbindingsförmåga i den här studien härrör till fiberns flexibilitet och förmåga att skapa stora kontaktytor med andra fibrer, vilket bidrar till papprets yt- och styrkeegenskaper.</p><p> </p><p>Ström 1 visade sig ha den högsta fiberbindningsförmågan, utvärderat som dragstyrka och densitet av långfiberark, samt yttre fibrillering och kollaps resistans index mätt i den optiska analysatorn FiberLab^TM. Akustisk emission och tvärsnittsanalyser visade samma resultat. Ström 5 visade sig ha den lägsta fiberbindningsförmågan, med en avtagande skala från Ström 1 till Ström 5. Andelen fibrer från injektet som gick ut med varje hydrocyklon-ström ansågs också vara ett mått på fibrernas bindningsförmåga i varje massa.</p><p> </p><p>Genom att kombinera fiberegenskaperna kollaps resistans och yttre fibrillering från den optiska mätningen på varje fiber genom linjär regression, kunde Bindnings Indikator (BIN) predikteras. Medelvärdet av Bindnings Indikator för varje hydrocyklon-ström korrelerar med dragstyrka för långfiber-labark.</p><p> </p><p>Det visade sig att predikterad Bindnings Indikator inte bara fungerade för Massa A och Massa B P16/R30 fraktionen, som var de fraktioner som användes i den linjära regressionen, utan även för Massa C-E, P16/R30, och Massa A-E P30/R50 som också visade goda korrelationer med långfiber-dragstyrka när de sattes in i BIN-formeln.</p><p> </p><p>BIN-formeln användes sedan för varje enskild fiber, i den rådata som levererats från FiberLab^TM. Detta gjorde det möjligt att få en BIN-distribution av fibrerna, d.v.s. en fördelning av fiberbindningsförmåga.</p><p> </p><p>Den här rapporten visar också hur det går att få BIN-distributioner också från mätningar på hela massan, för valbara fiberlängder, utan att först mekaniskt separera massan efter fiberlängd. Det är viktigt, då metoden är tänkt att användas som en industriell metod, och eventuellt som en online-metod. Förhoppningsvis kommer BIN-metoden att bli ett användbart verktyg för processutveckling- och optimering i framtiden.</p> / FSCN – Fibre Science and Communication Network / Bonding ability distribution of fibers in mechanical pulp furnishes