Slopping in BOS-processes poses many problems, most significantly to work environmentand process effectiveness. Due to the current weaknesses in slopping prediction systems afoaming slag suppression system with immediate effect is needed to prevent slopping.This project aims primarily to be a proof of concept for pressurized oxygen gas blowing as amean of foam steady-state height suppression to prevent slopping and secondarily toappreciate the viability of this concept economically.Five nozzles were designed and used to blow pressurized air onto foam made of silicon oil, atdifferent air flows. It was then determined which nozzle was the most effective by comparingheight difference with airflow. The airflow was compared to a life scale scenario to determinethe real flow rate which was used to determine economic viability.Results show that a nozzle with a circular small hole is the most effective nozzle requiring20 [ln min-1] to reduce the foam height by 69.6%. The real flow to achieve this would be0.605 [m3 s-1], however due to the cold models limitations this is not the true value. Theslopping suppression technique shows promise as a concept both economically andpractically. / Överkok i BOF-processen skapar många problem, mest i arbetsmiljön och minskar så väl produktionens effektivitet som takt. Eftersom de kontrollsystem som finns att tillgå idag     har vissa begränsningar så behövs det ett system för att motverka skumtillväxt med direkt inverkan för att hindra överkokning.Det här projektet ämnar huvudsakligen till att bevisa att ett pålagt flöde av syrgas kan trycka ned det skummande slaggets höjd och på så sätt förhindra överkokning och sekundärt till att bedöma konceptets ekonomiska rimlighet. Fem  munstycken designades  och användes till  att  blåsa tryckluft, med olika flöden, på skum bestående av   silikonolja.   Effektiviteten   hos   munstyckena   utvärderades   genom  att jämföra höjdskillnaden mot det pålagda luftflödet. Luftflödet jämnfördes sedan mot ett scenario i industriell skala och det verkliga luftflödet kunde därefter beräknas. Med detta  som  bakgrund gjordes en ekonomisk analys. Resultat visar att munstycket med ett litet cirkulärt håll är mest effektivt då det krävdes ett flöde på 20 [ln min-1] för att reducera skumhöjden med 69,6%. Det verkliga flödet beräknades till 0,605 [m3 s-1], men eftersom den kalla modellen har vissa begränsningar så är detta värde inte  sant.  Den  här  tekniken  för   att  förhindra   överkokning  ser   lovande   utbåde  ur  ett   ekonomiskt men också ur ett praktiskt perspektiv.

Yes / By controlling the crystallization behavior of poly(lactic acid) (PLA) in the presence of a hydrazide nucleating agent (HNA), PLA-HNA foams with enhanced microcellular structures were prepared via supercritical CO2 foaming. It was found that HNA can self-assemble into fibrillar networks, inducing the crystallization of PLA on their surface, and "shish-kebab"crystalline structures with high crystallinity formed, which can be maintained during the whole foaming process. Incorporation of HNA promoted the formation of gt conformers, improved the amount of dissolved CO2, hindered the escape of CO2, and increased the viscoelasticity of PLA. Compared with neat PLA foam, for PLA-HNA foam, the average cell diameter decreased obviously, from 64.39 to 6.59 μm, while the cell density increased up to nearly three orders of magnitudes, from 6.82 × 106 to 4.44 × 109 cells/cm3. Moreover, lots of fibrillar structures appeared and entangled with each other on the cell wall of the foam. By forming such dense micropores and enhanced fibrillar structures, PLA foam was highly reinforced with significantly improved compressive strength. / This research was financially supported by National Natural Science Foundation of China (grant no. 51773122) and State Key Laboratory of Polymer Materials Engineering (grant no. sklpme2019-2-21).

This work is concerned with the production of high performance polymer foams via a benign foaming process. The first goal of this project was to develop a process and the conditions necessary to produce a low density (>80% density reduction) foam from poly(arylene ether sulfone) (PAES). Water and supercritical carbon dioxide (scCO2) were used as the blowing agents in a one-step batch foaming process. Both water and scCO2 plasticize the PAES, allowing for precise control on both the foam morphology and the foam density. To optimize the foaming conditions, both thermogravimetric analysis and differential scanning calorimetery (DSC) were used to determine the solubility and the reduced glass transition temperature (Tg) due to plasticization of the polymer. It was determined that 2 hours was sufficient time to saturate the PAES with water and scCO2 when subjected to a temperature of 220 oC and 10.3 MPa of pressure. Under these conditions, a combination of 7.5% of water and scCO2 were able to diffuse into the PAES specimen, correlating to ~60 oC reduction in the Tg of the PAES. The combination of water and scCO2 produced foam with up to an 80% reduction in density. The compressive properties, tensile modulus, and impact strength of the foam were measured. The relative compressive properties were slightly lower than the commercially available structural foam made of poly(methacrylimide). The second objective of the dissertation was to enhance the compressive properties of the PAES foam, without concern for the foam density. Foam was produced over a range of density, by controlling the cell size, in order to optimize the compressive properties. Carbon nanofibers (CNFs) were also added to the PAES matrix prior to foaming to both induce heterogeneous nucleation, which leads to smaller cell size, and to reinforce the cell walls. Dynamic mechanical thermal analysis (DMTA), on saturated CNF-PAES, was used to determine the reduced Tg due to plasticization and establish the temperature for pressure release during foaming. DMTA proved to be more effective than DSC in establishing quantitative results on the reduction in the Tg. The CNF-PAES foam produced had compressive properties up to 1.5 times the compressive properties of the PAES foam. / Ph. D.

Chemical engineers have routinely used computational tools for modeling, optimizing, and debottlenecking chemical processes. Because of the advances in computational science over the past decade, multivariate statistics and machine learning have become an integral part of the computerization of chemical processes. In this research, we look into using multivariate statistics, machine learning tools, and their combinations through a series of case studies including a case with a successful industrial deployment of machine learning models for fermentation. We use both commercially-available software tools, Aspen ProMV and Python, to demonstrate the feasibility of the computational tools. This work demonstrates a novel application of ensemble-based machine learning methods in bioprocessing, particularly for the prediction of different fermenter types in a fermentation process (to allow for successful data integration) and the prediction of the onset of foaming. We apply two ensemble frameworks, Extreme Gradient Boosting (XGBoost) and Random Forest (RF), to build classification and regression models. Excessive foaming can interfere with the mixing of reactants and lead to problems, such as decreasing effective reactor volume, microbial contamination, product loss, and increased reaction time. Physical modeling of foaming is an arduous process as it requires estimation of foam height, which is dynamic in nature and varies for different processes. In addition to foaming prediction, we extend our work to control and prevent foaming by allowing data-driven ad hoc addition of antifoam using exhaust differential pressure as an indicator of foaming. We use large-scale real fermentation data for six different types of sporulating microorganisms to predict foaming over multiple strains of microorganisms and build exploratory time-series driven antifoam profiles for four different fermenter types. In order to successfully predict the antifoam addition from the large-scale multivariate dataset (about half a million instances for 163 batches), we use TPOT (Tree-based Pipeline Optimization Tool), an automated genetic programming algorithm, to find the best pipeline from 600 other pipelines. Our antifoam profiles are able to decrease hourly volume retention by over 53% for a specific fermenter. A decrease in hourly volume retention leads to an increase in fermentation product yield. We also study two different cases associated with the manufacturing of polyolefins, particularly LDPE (low-density polyethylene) and HDPE (high-density polyethylene). Through these cases, we showcase the usage of machine learning and multivariate statistical tools to improve process understanding and enhance the predictive capability for process optimization. By using indirect measurements such as temperature profiles, we demonstrate the viability of such measures in the prediction of polyolefin quality parameters, anomaly detection, and statistical monitoring and control of the chemical processes associated with a LDPE plant. We use dimensionality reduction, visualization tools, and regression analysis to achieve our goals. Using advanced analytical tools and a combination of algorithms such as PCA (Principal Component Analysis), PLS (Partial Least Squares), Random Forest, etc., we identify predictive models that can be used to create inferential schemes. Soft-sensors are widely used for on-line monitoring and real-time prediction of process variables. In one of our cases, we use advanced machine learning algorithms to predict the polymer melt index, which is crucial in determining the product quality of polymers. We use real industrial data from one of the leading chemical engineering companies in the Asia-Pacific region to build a predictive model for a HDPE plant. Lastly, we show an end-to-end workflow for deep learning on both industrial and simulated polyolefin datasets. Thus, using these five cases, we explore the usage of advanced machine learning and multivariate statistical techniques in the optimization of chemical and biochemical processes. The recent advances in computational hardware allow engineers to design such data-driven models, which enhances their capacity to effectively and efficiently monitor and control a process. We showcase that even non-expert chemical engineers can implement such machine learning algorithms with ease using open-source or commercially available software tools. / Doctor of Philosophy / Most chemical and biochemical processes are equipped with advanced probes and connectivity sensors that collect large amounts of data on a daily basis. It is critical to manage and utilize the significant amount of data collected from the start and throughout the development and manufacturing cycle. Chemical engineers have routinely used computational tools for modeling, designing, optimizing, debottlenecking, and troubleshooting chemical processes. Herein, we present different applications of machine learning and multivariate statistics using industrial datasets. This dissertation also includes a deployed industrial solution to mitigate foaming in commercial fermentation reactors as a proof-of-concept (PoC). Our antifoam profiles are able to decrease volume loss by over 53% for a specific fermenter. Throughout this dissertation, we demonstrate applications of several techniques like ensemble methods, automated machine learning, exploratory time series, and deep learning for solving industrial problems. Our aim is to bridge the gap from industrial data acquisition to finding meaningful insights for process optimization.

M-Tech: Chemistry (Vaal University of Technology) / ABSTRACT The research was aimed to study the causes of excessive foaming in a waste water treatment plant. Although the activated sludge process has been adopted to treat this industrial waste water , lots of problems were experienced by the inhibitory effects of toxic compounds that are found in industrial effluents and the foaming stability that was very high. Industrial waste water treatment using sludge processes was found to be more challenging than the normal municipal waste water treatment although the principle is the same; the foaming tendencies were found to be more in industrial waste water. In this study the composition of influents to the waste water treatment plant and operating parameter’s effects on foaming tendencies were examined. The foaming potential in the plant was found to be chemically related due to high contamination of compounds such as phenols, which played a major role in formation of stable foam. It was recommended that there must be pretreatment of the incoming influents to minimize their impact to waste water treatment.

Wood Plastic Composites (WPC) have advantages over natural wood such as improved stiffness, recyclability, and waste minimization. However, issues such as the difficulty of processing WPC with conventional methods, volatile emission from the wood and the composites’ lack of strength must be addressed. A system for continuous extrusion of rectangular profiles of WPC was developed and some critical processing strategies were identified. The use of a lubricant and a calibrator also improved the profile extrusion of WPC. In this work, glass was also added to improve WPC’s mechanical strength. Generally, a glass content of 2.5% appears to improve the properties but further addition does not have a significant effect. Foaming of WPC, which can enhance their properties, was investigated through studying the effect of heating time and temperature on void fraction and cell density. / UOIT

Metal foams have found increasing applications in a wide range of structural and functional products, due to their exceptional mechanical, thermal, acoustic and electrical properties and offer great potential for lightweight structures for energy absorption in packaging during impact at high velocities. Metal foam structures have densities only fractions of that of a solid structure and have high specific strength and higher stiffness than other contemporary packaging materials. Therefore, the metal foam in particular “Aluminium Foam” has an important application as packaging material for transportation of Reactor fuels and Radioactive samples. Nuclear materials are transported in packages which should meet stringent safety standards like impact resistance, thermal shock etc. Therefore, in the transportation of the above materials, aluminium foam can play a key role in providing a cushion for absorption of shock and impact. The aim of this work is to develop a process for fabrication of aluminum foam. Two methods are experimented to manufacture metal foams. The first method involves mixing of a foaming agent in a liquid aluminium pool and the subsequent cooling of the melt while hydrogen is released from the foaming agent. The second method of metal foaming process is based on a procedure consisting of a base metal and a foaming agent, which are milled for homogeneous mixing and then pre-compacted by cold isostatic pressing. This is followed by cold/warm extrusion. The extruded piece is then heated up to a certain foaming temperature. The heating process leads to partial metal melting as well as to the release of the hydrogen gas and consequently to the formation of metal foam in the semi-solid state. In this thesis, the technology for fabrication of Al foam having a density of around 0.2-0.3 g/cm3 has been made & discussed in detail. The effects of various fabrication parameters like compaction pressure, extrusion ratio and foaming temperature on the formation of the Al foam are discussed. The quality of fabricated Al foams is characterized in terms of density, microstructure, porosity content etc. The various mechanical properties like yield strength, tensile strength and impact energy of the Al foams are evaluated in order to understand their behavior under different conditions. The typical values of Young’s modulus, plateau stress, densification strain and energy absorbed for the foam tested are tabulated. The observations, which are made from the data, can be briefly quoted as under: a) As the length of the specimen increases, plateau stress increases which increases the energy absorption. b) The energy absorption for Al-20% Mg alloy has been found to be minimum. The foam exhibited brittle behaviour and crumbled under load application. c) Young’s modulus varies in the range of 0.057 – 0.13 GPa for the foam. d) As density increases, Young’s modulus also increases and correspondingly the energy absorption value increases for Al-foam. It is found that the variation in the plateau stress with density is marginal. But the strain value was found to be dependent on the alloy composition and the density. The strain obtained for all cases was found to be very near to 75-90%. Al-20%Mg alloy showed an inferior behaviour compared to pure Al. It showed a lesser plateau stress and crumbled while testing. This shows that this alloy is highly brittle in nature. Also, the Al-Mg foam obtained did not exhibited good luster.

Hemp seed proteins (HSP) were investigated for physicochemical and functional properties in model food systems. In addition, the HSP were enzymatically digested and the released peptides investigated as potential therapeutic agents. Membrane isolated HSP (mHPC) were the most soluble with >60% solubility at pH 3-9 when compared to a maximum of 27% for isoelectric pH-precipitated proteins (iHPI). However, iHPI formed emulsions with smaller oil droplet sizes (<1 µm) while mHPI formed bigger oil droplets. The iHPI was subjected to enzymatic hydrolysis using different concentrations (1-4%) of six proteases (pepsin, pancreatin, flavourzyme, thermoase, papain and alcalase) to produce various HSP hydrolysates (HPHs). HPHs had strong in vitro inhibitions of angiotensin converting enzyme (ACE) and renin activities, the two main enzyme systems involved in hypertension. Oral administration of the HPHs to spontaneously hypertensive rats led to fast and persistent reductions in systolic blood pressure. The HPHs also inhibited in vitro activities of acetylcholinesterase (AChE), a serine hydrolase whose excessive activities lead to inadequate level of the cholinergic neurotransmitter, acetylcholine (ACh). Inadequate ACh level in the brain has been linked to neurodegenerative diseases such as dementia and Alzheimer’s disease (AD); therefore, AChE inhibition is a therapeutic target. The 1% pepsin HPH was the most active with up to 54% AChE inhibition at 10 µg/mL peptide concentration. The 1% pepsin HPH (dominated by <1 kDa) was subjected to reverse-phase HPLC peptide purification coupled with tandem mass spectrometry, which led to identification of several peptide sequences. Some of the peptides inhibited activities of both animal and human AChE forms with LYV being the most potent against human AChE (IC50 = 7 µg/ml). Thus the LYV peptide may serve as a useful template for the development of future potent AChE-inhibitory peptidomimetics. In conclusion, several novel AChE-inhibitory peptides were discovered and their amino acid sequences elucidated for the first time. Results from this work identified HSP products that could serve as functional ingredients in the food industry. The work also produced and confirmed the in vitro AChE-inhibitory activities of several new peptide sequences that may serve as therapeutic agents for AD management. / October 2015

Dissolved and Colloidal substances (DSC) and metals are released from woodduring thermomechanical pulp (TMP) production. These components have atendency to accumulate in process waters, as the water circulation systems inintegrated paper mills are closed. Disturbances such as pitch depositions in thepaper machine (pitch problems), specks in the paper, decreased wet and drystrength, interference with cationic process chemicals, and impaired sheetbrightness and friction properties appear when DSC are present. Transition metalions such as manganese results in higher consumption of bleaching chemicals(hydrogen peroxide) and lowers the optical quality of the final product, andaddition of complexing agents, such as EDTA or DTPA, to prevent this is needed.The never ending trends to decrease water consumption and increase processefficiency in pulp and paper production emphasizes that it is very important bothto know the effects of wood substances on pulping and papermaking and to beable to remove them in an efficient way. From a biorefinery point of view, DSCcomponents can be promising renewable raw materials for biofuels, bio‐basedchemicals and materials.In this thesis, a new approach using induced air flotation (IAF) without a cationicpolyelectrolyte addition for the removal of pitch and metal ions from mechanicalpulp mill process waters is presented. The induced air flotation of different processwaters is facilitated by the addition of a chelating surfactant and different foamingagents. The influence of the pH value, temperature and foaming agentconcentration on the flotation efficiency has been investigated. The investigations presented show that the disturbing components can be removed from TMP presswater to a high extent. A 90% decrease in turbidity and a 91% removal of lipophilicextractives (i.e. resin and fatty acids, triglycerides, sterols and steryl esters) fromunbleached and bleached TMP process water can be obtained by addition of acationic surfactant as foaming agent during flotation. Lower amount of foamingagent is needed to purify efficiently bleached TMP process water, than unbleached.Additionally, fibres located in TMP press water are not removed with the foamfraction but purified. A retained concentration of hydrophilic extractives (i.e.hemicelluloses and lignans) in the process water indicates that the flotation isselective. Moreover, by introduction of a new recoverable surface activecomplexing agent, a chelating surfactant, manganese ions in the form of chelatescan be successfully removed from the pulp fibres and separated from the processwater in the same flotation process. Furthermore, from the purified unbleachedTMP process water a 90% recovery of dissolved hemicelluloses by anti‐solventprecipitation was obtained.The findings presented above indicate new possibilities for the internal watercleaning stage to decrease DSC emissions to recipient and for recovery of valuableraw materials from purified process water if flotation technology is applied in anintegrated mechanical pulp mill. / FORE

Cette thèse est dédiée à l’étude de l’effet de la configuration des agitateurs (pales planes) et la nature du tensioactif sur la dispersion de gaz dans un liquide en vue d’obtenir un produit foisonné. Cette étude est menée à deux échelles pilote et locale. Le premier chapitre est dédié à une étude à l’échelle pilote. Les résultats ont montré qu’à conditions opératoires fixées, lorsque les agitateurs sont collés et décalés, l’aspect distributif de la dispersion de gaz est amélioré. L’aspect dispersif (taille des bulles), en revanche, reste peu sensible à la configuration des agitateurs. Les protéines sériques« WPI » comme agent tensioactif améliore l’efficacité de la rétention de gaz alors que le Tween 20 la réduit et provoque l’augmentation de la taille des bulles. Le deuxième chapitre concerne une approche locale qualitative (observation optique) et quantitative (détermination de capillaire critique). L’étude qualitative a montré que l’ajout d’un angle de décalage modifie l’écoulement du liquide et les bulles suivent la trajectoire imposée par le liquide. Lorsque les protéines WPI est utilisé comme agent tensioactif, sous l’action de la contrainte de cisaillement, les bulles subissent une déformation qui se termine par une rupture par extrémité. Un système couette a permis de déterminer un nombre capillaire critique correspondant à cette rupture. Par contre, en présence du Tween 20, la déformation ne conduit jamais à une rupture par extrémité. Le troisième chapitre de ce travail est dédié à une étude numérique de l’hydrodynamique de l’écoulement. Cette étude a permis de confirmer les résultats obtenus par l’approche qualitative. A titre d’exemple, un décalage entre deux agitateurs collés conduit à la multiplication des zones de vortex, à l’apparition des élongations supplémentaires et d’effet venturi favorables à l’aspect distributif de la dispersion. L’étude numérique montre également que le gradient maximal et moyen de vitesse reste indépendant de la configuration, ce qui explique pourquoi la taille moyenne est indépendante de la configuration. / Flat-blad impellers configuration coupled with tensioactif agents have been used to study gas dispersion in foaming process. The work has been conducted at pilot and local scales. The first chapter is devoted to a study at the pilot scale. The results showed that under a given operating conditions, a shift between two glued successive impellers promotes distributive aspect of the gas dispersion. However the dispersive aspect (bubble size), remains independent of the impellers configuration. The pilot-scale experiments have also shown that the "WPI" enhance foaming efficiency, while, Tween 20 reduces it and increases the size of the bubbles. The second chapter links with a qualitative (optical observation) and quantitative (determination of critical capillary) at local scale. It has been observed that shifted-impellers modify the flow pattern and promotes the distributive aspect of the mixture. When the WPI is used as a surfactant, shear stress induces bubble deformation until a tip-breakup occurs. Using a Couette system, it has been shown that there exist a critical capillary number corresponding to this rupture. However, the deformation does never induced tip-breakup when using Tween 20. The third chapter of this work is devoted to a numerical study of liquid hydrodynamics under different configuration. It appears that the configuration where the impellers are glued and shifted induces the multiplication of the vortex, the appearance of additional elongations and venturi effect. These effects seem to improve the distributive aspect of mixing in agreement with the results obtained previously. The numerical study also shows that the maximum and average shear gradient is independent of the configuration. This result explains why the mean bubble size remains independent of the configuration.