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Aplicação de um modelo numérico na otimização de fornos alimentícios usando o OpenFOAM® / Application of a numerical model in optimizing food furnaces using OpenFOAM®Verdério Júnior, Sílvio Aparecido [UNESP] 02 September 2015 (has links) (PDF)
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000855350.pdf: 5394081 bytes, checksum: 5f4d040bbbe3297c23997fc77559961e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os fornos contínuos do tipo túnel, dada a sua maior flexibilidade no aquecimento e alta produtividade, tornaram-se a melhor opção para o processamento de produtos alimentícios industrializados. O combustível utilizado nos queimadores é normalmente o gás natural, que apesar das incertezas e oscilações dos custos, vem ganhando espaço na indústria nacional. No presente trabalho foram desenvolvidos diversos modelos físicos tridimensionais - classificados em modelos de testes, de análises paramétricas e de otimização - e utilizados no estudo, modelagem e otimização de fornos alimentícios contínuos do tipo túnel com aquecimento indireto. Utilizou-se o software livre de código aberto OpenFOAM® para a modelagem dos problemas propostos. A geometria e condições operacionais utilizadas foram obtidas junto a uma empresa alimentícia bauruense para o processo de pré-assamento de pizzas. Os efeitos da geometria, malha, condições iniciais e de contorno, algoritmo de acoplamento pressão-velocidade, forças de campo, trocas de calor por radiação através dos modelos fvDOM e view/Factor e modelagem RANS k- E para a turbulência foram avaliados sobre os parâmetros do escoamento. O algoritmo de acoplamento pressão-velocidade mais indicado ao problema proposto é o SIMPLE. A utiilzação do modelo de radição viewFactor mostrou-se mais adequado. As trocas de calor por convecção sobre a esteira mostraram-se pouco significantes em relação as trocas por radiação, demonstrando a importância da correta modelagem desse fenômeno. Testes para diversas geometrias de forno foram realizados. O forno'com menor razão de aspecto geométrico e consequentemente, de menor altura, mostrou-se mais eficiente, embora isto possa provocar, na prática, limitações na sua utilização / Because of the better flexibility in warning and high production, the continuous furnace tunnel is the better option to the processing of industrialized food products. The fuel used in the burners is usually natural gas, which despite the uncertainties and fluctuantions in costs, is becoming more popular in national industry. In this work, several three-dimensional physical models were developed - classified in testing models, parametric analysis and optimization - and used to the study, modeling and optimization of continuous food furnaces of tunnel type with indirect heating. It was chosen the OpenFOAM® opensource software for modeling of proposed problems. The geometry and the operating conditions were based in a bauruense food company to the process of pre-baking of pizzas. The effects of geometry, mesh, initial and boundary conditions, pressure-velocity coupling algorithm, field strengths, radiation heat exchanges using fvDOM and view/Factor, and modeling RANS k - E for turbulence to were evaluated about the flow parameters. The SIMPLE is the most indicated pressure-velocity coupling algorithm to this problem. The use of viewFactor radiation model proved more adequate. The heat exchanges by convection over the treadmill have proved little significant compared the heat exchanges by radiation, demonstrating the importance of correct modeling of this phenomenon. Differents geometries tests were made, and the furnace with the smaller ratio aspect geometric and, consequently, smaller height, showed to be most efficient, although this may result in practice, in limitations in its use
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Aplicação de um modelo numérico na otimização de fornos alimentícios usando o OpenFOAM® /Verdério Júnior, Sílvio Aparecido. January 2015 (has links)
Orientador: Vicente Luiz Scalon / Co-orientador: Alcides Padilha / Banca: Santiago Del Rio Oliveira / Banca: Pedro Miguel Rebelo Resende / Resumo: Os fornos contínuos do tipo túnel, dada a sua maior flexibilidade no aquecimento e alta produtividade, tornaram-se a melhor opção para o processamento de produtos alimentícios industrializados. O combustível utilizado nos queimadores é normalmente o gás natural, que apesar das incertezas e oscilações dos custos, vem ganhando espaço na indústria nacional. No presente trabalho foram desenvolvidos diversos modelos físicos tridimensionais - classificados em modelos de testes, de análises paramétricas e de otimização - e utilizados no estudo, modelagem e otimização de fornos alimentícios contínuos do tipo túnel com aquecimento indireto. Utilizou-se o software livre de código aberto OpenFOAM® para a modelagem dos problemas propostos. A geometria e condições operacionais utilizadas foram obtidas junto a uma empresa alimentícia bauruense para o processo de pré-assamento de pizzas. Os efeitos da geometria, malha, condições iniciais e de contorno, algoritmo de acoplamento pressão-velocidade, forças de campo, trocas de calor por radiação através dos modelos fvDOM e view/Factor e modelagem RANS k- E para a turbulência foram avaliados sobre os parâmetros do escoamento. O algoritmo de acoplamento pressão-velocidade mais indicado ao problema proposto é o SIMPLE. A utiilzação do modelo de radição viewFactor mostrou-se mais adequado. As trocas de calor por convecção sobre a esteira mostraram-se pouco significantes em relação as trocas por radiação, demonstrando a importância da correta modelagem desse fenômeno. Testes para diversas geometrias de forno foram realizados. O forno'com menor razão de aspecto geométrico e consequentemente, de menor altura, mostrou-se mais eficiente, embora isto possa provocar, na prática, limitações na sua utilização / Abstract: Because of the better flexibility in warning and high production, the continuous furnace tunnel is the better option to the processing of industrialized food products. The fuel used in the burners is usually natural gas, which despite the uncertainties and fluctuantions in costs, is becoming more popular in national industry. In this work, several three-dimensional physical models were developed - classified in testing models, parametric analysis and optimization - and used to the study, modeling and optimization of continuous food furnaces of tunnel type with indirect heating. It was chosen the OpenFOAM® opensource software for modeling of proposed problems. The geometry and the operating conditions were based in a bauruense food company to the process of pre-baking of pizzas. The effects of geometry, mesh, initial and boundary conditions, pressure-velocity coupling algorithm, field strengths, radiation heat exchanges using fvDOM and view/Factor, and modeling RANS k - E for turbulence to were evaluated about the flow parameters. The SIMPLE is the most indicated pressure-velocity coupling algorithm to this problem. The use of viewFactor radiation model proved more adequate. The heat exchanges by convection over the treadmill have proved little significant compared the heat exchanges by radiation, demonstrating the importance of correct modeling of this phenomenon. Differents geometries tests were made, and the furnace with the smaller ratio aspect geometric and, consequently, smaller height, showed to be most efficient, although this may result in practice, in limitations in its use / Mestre
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Analysis of blast furnace lining/cooling systems using computational fluid dynamicsJoubert, Hugo 07 September 2012 (has links)
M.Ing. / In this study it is shown that numerical analysis, and more specifically computational fluid dynamics can be used to investigate, compare, predict and design lining/cooling system combinations for blast furnaces’ in order to ensure longer campaign life and better performance. Three currently available cooling systems namely, copper staves are investigated. These combined with four different refractory materials, namely high alumina, silicon carbide, semi-graphite and graphite, stated in order of increasing thermal conductivity.
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'n Ondersoek na die elektromagnetiese verbetering van die induksiesmelting van metaleDorland, Pieter 29 May 2014 (has links)
M.Ing. (Electrical And Electronic Engineering) / The metals manufacturing industry is the link between the mining industry, where the ore is mined, and the manufacturing industries, where metals are utilized to create a wide range of products. Melting processes.are used in the manufacturing of metals from the ore, of which induction melting is one of the possible melting processes. In this study the improvement of induction melting of metals is investigated. A new topology for an induction melting furnace is proposed, and this topology is thoroughly investigated. The induction melting process is influenced by certain user-controlled variables as well as the electromagnetic layout of the furnace. In this study, the influence of these variables on the performance of the furnace are investigated through finite element simulations and insight is also gained into the influence of the electromagnetic layout of the system. An experimental induction melting furnace is described in this study, investigated and compared to the predictions from the simulations. Improvements from structural, thermal and measuring viewpoints are also investigated and implemented.
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Computer vision based method for electrode slip measurement in a submerged arc-furnaceJordan, Dominic Timothy 04 June 2012 (has links)
M. Ing. / The purpose of this study is to investigate the use of computer vision techniques to measure the electrode slip. The study investigates a potential location for camera placement in the furnace housing, as well as the use of computer vision algorithms that could be used to solve the problem. A slip measurement algorithm is then designed, implemented and tested. The implemented slip measurement algorithm is based on the manual slip measurement technique, by measuring relative electrode and slip arm displacement between the electrode and the slip arm. The algorithm uses SURF invariant features to extract the electrode features and slip arm features in one frame, and match these features to the next frame SURF. Scene calibration is then used to relate the pixel slip measurement to a metric distance measurement. The experimental results proved that there is scope for applying computer vision techniques to address the slip measurement problem, using a single HD camera. However, there is room for improvement and the recommendations and future work are also discussed.
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Evaluation of the REAS test for blast furnace charge materialsVan der Vyver, W.F. (Wilhelmina Fredrika) 18 December 2006 (has links)
During the past two decades many efforts have been made to increase the control of blast furnace conditions to ensure a homogeneous product. The dissections on blast furnaces by various iron and steel companies in Japan in the early 70s provided valuable information on the high temperature properties of charging material. Standard tests (ISO) to determine ore, sinter and pellet qualities only provide information of up to 1100°C . By using the REAS apparatus - a high temperature reduction vessel that simulates the blast furnace process from stockline to melting - the high temperature properties of burden materials have been investigated. The REAS process not only provides an insight into the reactions occurring during the softening and melting process but a range of indices with which to judge the blast furnace performance. Since 1993 new developments started and a test method for Iscor blast furnaces was specifically developed. Although certain indices have been established, uncertainties around the melting mechanisms still existed. These uncertainties include: • Why does the maximum pressure over the sample bed vary extensively between different samples? • Why does a temperature decrease occur only in certain samples and what determines the extent of the temperature decrease? • Which low melting phase forms that causes the initial rise in pressure drop over the sample bed? Four tests were performed on a mixture of Sishen and Thabazimbi ore to determine the phase changes in the test sample. During the reduction of the iron ore, five distinct phases are present. Above 1200°C two liquid phases, an alkali rich phase and a liquid phase with a fayalite composition is present. The rest of the iron reports at different stages in various forms of metallic iron and wustite. Small amounts of a high melting oxide phase, hercynite, also occurs. Softening of the sample is said to occur when the ΔP over the sample bed increases by more than 200 mm H2O. For the specific tests evaluated, this occurred at 1200°C. At this temperature, the liquid with a fayalite composition as well as the alkali rich liquid are present. The formation of the low melting fayalite phase with a high viscosity appears to cause the sudden rise in ΔP. A temperature arrest occurs at the same time supporting the suggestion that liquid formation is responsible for the pressure increase. The results indicate that the mechanisms responsible for the observed pressure drop (decreased gas permeability) and dripping may well be different from those given in the literature. The literature mechanisms emphasise the importance of the amount of FeO available to act as flux for the silica which is present as gangue; hence a greater degree of (indirect) reduction below the melting point of fayalite gives poorer fluxing of silica since less FeO is available. However, the charge materials considered in this study appear to be of substantially higher grade than those used in the previous work. For this reason, there does not appear to be any shortage of FeO to act as flux. This abundance of FeO, and the observation that the peak in pressure drop is not associated with any great change in the amount of liquid, together imply that the literature mechanism regarding changes in the amount and composition of the liquid (i.e. becoming more Si02-rich and viscous as the FeO is reduced) cannot explain the pressure fluctuations observed here. Rather, the increase in pressure appears to be a joint effect of liquid being present (giving the first increase in pressure) and compaction of the sample. Loss of voidage in the sample by this substantial amount of compaction appears the likely cause of the pressure increase. The subsequent decrease in the pressure drop is probably associated with lower viscosity as the sample temperature increases. The importance of compaction means that the amount of indirect reduction does playa role in the development of the pressure drop, but not for the reasons cited in the literature. Pure iron is more malleable than the oxides, and reduction gives a porous iron structure which is more easily compacted. F or both these reasons, the metallic product of indirect reduction favours compaction (and hence the pressure increase). The sharp increase in reduction rate close to the peak pressure presumably results from better contact between the remaining iron oxide (in the fayalite-based liquid, and wustite) with the coke reductant, so favouring direct reduction; this increased reduction (endothermic because of the Boudouard reaction) results in one of the noticeable temperature arrests on the sample temperature curve. The correspondence between the temperature arrests and the changes within the sample do imply that these arrests can be used to gain some information on the reduction mechanisms. However, the reliability of the temperature arrests as indicators of the state of the sample and the reaction conditions within the sample must be tested by further work. / Dissertation (MSc (Metallurgy))--University of Pretoria, 1998. / Materials Science and Metallurgical Engineering / unrestricted
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Comparison of a fluidized bed combustor and its scale modelWalsh, John Joseph January 1980 (has links)
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by John Joseph Walsh. / B.S.
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Analysing fly-ash erosion in coal-fired boilers using compational fluid dynamicsKloppers, Johannes Christiaan 16 April 2007 (has links)
Please read the abstract in the section 00front of this document / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted
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The gasification of biomass in a fluidized bed reactorSingh, Satish K January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
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A generic, semi-empirical approach to the stochastic modelling of bath-type pyrometallurgical reactorsEksteen, Jacobus Johannes, Reuter, M. A., Bradshaw, S. M. 03 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2004. / 388 leaves printed on single pages, preliminary pages i- xv and numbered pages 1-371. Includes bibliography, list of tables and figures. / Digitized at 330 dpi black and white and 330 dpi color PDF format (OCR), using KODAK i 1220 PLUS scanner. / ENGLISH ABSTRACT: Bath type furnaces have become an established technology for the intensive smelting,
converting and refining of primary and secondary raw materials. Since these furnaces
normally have large inventories, long time constants and complex metallurgies, a dynamic
model-based prediction strategy is the only feasible approach to operator decision support and
process control. This dissertation presents a semi-empirical approach to the stochastic
modelling of bath-type pyrometallurgical reactors, which leads to a generic model type called
the Equilib-ARMAX model. The modelling approach is applied to three case studies:
• A nickel-copper matte converting operation using a submerged lance injection reactor
• A chromite smelting operation to produce high carbon ferrochrome using a direct current
(DC) plasma smelting furnace
• An ilmenite smelting operation to produce high titania slag and pig iron, using a direct
current (DC) plasma smelting furnace.
In each case, the industrial operations were analysed with regard to the practical and
technological constraints which influence the type and quality of the process data. The
fundamental process phenomena associated with each operation have been analysed to
ascertain which fundamental variables should be included within the overall semi-empirical
approach, without sacrificing model transparency, simplicity, accuracy and calculation time.
It was considered that an overly complex model would be inappropriate given that data from
industrial smelting operations show significant random variance.
The thermochemistry and phase equilibria associated with each operation are discussed in
detail, as they become the fundamental backbone of the semi-empirical models. The equilibria
have been modelled with software that uses non-ideal solutions models and Gibbs free energy
minimisation to predict the phase and chemical equilibria that could be expected for a given
feed recipe and operating temperature. As the thermodynamic modelling software is not stable
within an industrial environment, an artificial intelligent mapping technique has been
developed to map process inputs to equilibrium outputs. A multi-layer perceptron neural
network has been used as the convenient mapping method to represent equilibrium. The
neural networks were trained using tens of thousands of feed recipes, where the feed
component ratios were varied based on a 3N factorial design. The amounts and chemistries of
all equilibrium phases could be calculated with high accuracies (R2 > 0.95) in all cases. Further stochastic analysis and modelling require additional information about the property
distributions associated with each measurement. The homogeneities of the furnace products
(slag, alloy and flue dust) critically influence the level of confidence that one can associate
with plant measurements. The homogeneities were characterised for the DC plasma arc
furnaces and they were benchmarked against a submerged arc furnace. It was found that the
homogeneity varied per element, with silicon and sulphur tending to show highest variations
in the alloy melts. The observation that the variation in these two elements are both high can
partially be attributed to the fact that SiS evaporates from the bath surface, especially in
regions close to the arc attachment zone. A significant negative correlation was found
between the relative standard deviation per tap (using silicon) and the degree of superheat /
subcooling of the alloy, indicating that the homogeneity can be strongly influenced by the
changes in rheology due to subcooling below the liquidus (which leads to the precipitation of
solid phases and increases the observed melt viscosity). Mixedness or homogeneity and data
uncertainty are therefore inseparably linked.
The relative standard deviations associated with the homogeneity characterisation, as well as
known sampling and assaying variances were used to develop reconciled material balances
based on measured plant data. Material balance closure was therefore obtained within the
inherent uncertainties of the plant data. Biases in the plant data were identified simultaneously
with data reconciliation. Moreover, it was shown using Fast Fourier Power Spectra and statespace
analysis that the data reconciliation was a good low-pass filter, as it extracted the major
process trends components in the noisy data and it also improved the overall dynamic
behaviour characteristics of the data.
Finally systems identification techniques were used to develop dynamic transfer function
models that were linear in the parameters to be estimated. These systems models were based
on the reconciled plant data and equilibrium predictions. The final systems models are
therefore equilibrium-autoregressive-moving-average models with exogenous variables
(Equilib-ARMAX). The model parameters can be estimated recursively using a simple least
squares method. The final models could dynamically predict the metallurgy of the subsequent
tap 4-6 hours in advance, based on a given suite of set-points, within the inherent accuracy of
the data. These models may be used to suggest the optimal operating conditions through an
operator guidance system, or more simply, the models are simple enough to be used in a
spreadsheet on a manager's desk. / AFRIKAANSE OPSOMMING: Bad-tipe oonde is reeds 'n gevestigde tegnologie wat algemeen gebruik word vir die
intensiewe smelting, omsetting en raffinering van primere en sekondere roumateriale.
Aangesien hierdie oonde normaalweg groot inventarisse, lang tydkonstantes en komplekse
metallurgiee het, is dinamiese, modelgebaseerde voorspelling die enigste uitvoerbare
benadering tot operateur besluitnemingsteunstelsels en prosesbeheer. Hierdie proefskrif stel 'n
nuwe generiese, semi-empiriese benadering voor om die bad-tipe oonde stogasties te
modelleer en lei tot die sogenaamde Equilib-ARMAX model. Die modelleringsbenadering
word geevalueer deur drie gevallestudies:
• 'n Nikkel-koper swawelsteen omsettingsproses in 'n dompel-Ians inspuit reaktor
• 'n Chromiet smeltingsproses om hoe-koolstof ferrochroom te produseer in 'n gelykstroom
(GS) plasmaboogoond
• 'n Ilmeniet smeltingsproses om hoe titania slak en ruyster te produseer in 'n gelykstroom
(GS) plasmaboogoond.
In elke geval is die industriele prosesse ontleed met betrekking tot die praktiese en
tegnologiese beperkings wat die tipe en die gehalte van die prosesdata beinvloed. Die
fundamentele prosesgedrag van elke proses is ontleed om te bepaal welke fundamentele
veranderlikes ingesluit moet word in die semi-empiriese benadering, sonder om model
deursigtigheid, eenvoud, akkuraatheid en berekeningstyd in te boet. Die ontwikkeling van
oor-komplekse modelle is beskou as ongepas, gegewe dat die data van industriele
smeltingsprosesse beduidende onsekerhede toon.
Die termochemiese en fase-ewewigte geassosieer met elke proses word breedvoerig bespreek,
aangesien dit die fundamente1e grondslag van die semi-empiriese modelle verskaf. Die
ewewigte is gemodelleer met rekenaar simulasie-programmatuur wat nie-ideale oplossingsmodelle
en Gibbs vrye-energie minimering gebruik om die fase en chemiese ewewigte, wat
verwag kan word vir 'n gegewe toevoerresep en bedryfstemperatuur, te voorspel. Aangesien
termodinamiese modelleringsprogrammatuur normaalweg nie stabiele gedrag toon in 'n intydse
industriele omgewing nie, word kunsmatig intelligente projeksietegnieke gebruik om
prosesinsette te projekteer na die ekwavilente ewewigsvoorspellings. 'n Multilaag perseptron
neurale netwerk is gebruik as 'n eenvoudige metode om hierdie ewewigsprojeksies voor te
stel. Die neurale netwerke is afgerig deur van tienduisende toevoer resepte gebruik te maak. Die verhoudings van die komponente in die voer is gewissel gebaseer op 'n 3N
faktoriaalontwerp. Die hoeveelhede en samestelling van al die ewewigsfases kon in alle
gevalle bereken word met hoe akkuraatheid (R2 > 0.95).
Verdere stogastiese analise en modellering is slegs moontlik met kennis oor die
eienskapsverspreidings geassosieer met elke komponent. Die homogeniteite van die
oondprodukte (slak, legering en vlieg-as) bepaal, tot 'n groot mate, die betroubaarheidsvlak
van die aanlegmetings. Homogeniteite is gekarakteriseer vir die GS-plasmaboogoonde en is
vergelyk met die homogeniteite wat in dompelboogoonde gevind word. Die homogeniteite het
gevarieer per komponent. Silikon en swawel neig om die grootste ruimtelike variasies te toon
in die legerings wat bestudeer is. 'n Beduidende negatiewe korrelasie is gevind tussen die
relatiewe standaardafwyking per tap (gebaseer op silikon) en die graad van superverhitting /
onderverkoeling van die legering. Dit dui aan dat die homogeniteit sterk beinvloed word deur
veranderinge in die smelt reologie. Vermenging, reologie, homogeniteit en data onsekerheid
(integriteit) is daarom ten nouste gekoppel.
Die relatiewe standaardafwykings geassosieer met die homogeniteitsbepaling, asook die
monsternemings- en ontledingsvariansies, is gebruik om die aanlegdata te rekonsilieer
onderhewig aan die behoud van die komponent en totale stroom massabalanse. Die
massabalanse is dus gesluit deur aanpassings aan die metings te maak binne die inherente
onsekerhede in die data. Sistematiese foute in die data is gelyktydig met die rekonsiliasie
geidentifiseer. Verder is deur diskrete Fourier energiespektra en toestand-ruimte analises
getoon dat massabalans-rekonsiliasie dien as 'n goeie seinfilter om hoe-frekwensie geraas te
verminder en tergelykertyd die dinamiese gedragseienskappe van die data te verbeter.
Stelsel-identifikasietegnieke is gebruik om dinamiese oordragsfunksiemodelle te ontwikkel
wat linieer is met betrekking tot die modelparameters. Hierdie stelselmodelle is gebaseer op
gerekonsilieerde data, eksogene prosesdata en ewewigsberekeninge, en word vervolgens
ewewigs-autoregressiewe-lopende-gemiddelde modelle met eksogene veranderlikes (Equilib ARMAX)
genoem. Die modelparameters kan deur gewone kleinste-kwadrate metodes beraam
word. Die finale modelle kan die metallurgie van toekomstige tappe 4-6 uur voortydig
voorspel, gebaseer op beskikbare stelpunte en binne die inherente presisie van die data.
Hierdie modelle kan gebruik word om optimale bedryfskondisies vir prosesbeheer te
identifiseer, en is eenvoudig genoeg om in sigbladformaat op 'n aanlegbetuurder se rekenaar
gebruik te kan word.
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