Organic esters are an important class of industrial and commercial chemicals that can be found in solvents, plasticizer, food flavours, detergents, agrochemicals, and pharmaceuticals. The most common way to synthesis organic esters is with esterification or transesterification. Where esterification was the chosen method in this thesis.  This thesis provides a techno-economic assessment on the production of propyl acetate and glycerol trivalerate through different continuous routes that is than compared with batch production under the same conditions. Simulations was done on trivalerate due to limited literature and data on pentaerythritol tetravalerate. Different continuous technologies that have been assessed in this thesis was plug flow reactor (PFR), Reactive Distillation (RD), and Reactive – Extractive Distillation (RED). The production of mono- and polyol esters with different unit operators was simulated in Aspen Plus V.14. Techno-Economic analysis was conducted with APEA (Aspen Process Economic Analyzer), where cost of raw materials, products, and utilities was inserted to evaluate annual operating cost and product sale. Reaction kinetic for esterification of trivalerate was estimated by obtained values from simulations of a Gibbs reactor in Aspen Plus at four different temperatures. Kinetics was estimated by applying the relation between the chemical equilibrium constant and the Arrhenius equation. Where rate constant and activation energy for forward and revers reaction was obtained by varying min and max values for lsqcurvefit in MATLAB and then validate results with published kinetics.  Results from production of propyl acetate with batch, PFR and RED provides an annual profit of approximately 1 M$ at a capacity of 41.65 kton/year. The three different process provides also approximately an equal capital cost, operating cost, equipment cost, and installed cost according to APEA. RED provided the lowest propyl acetate yield at 93%, batch and PFR provided a propyl acetate yield of 94%.  Results from production of trivalerate with batch, PFR, and RD provides an annual profit of 5.4, 5.78, and 9.2 M$ at a capacity of approximately 5 kton/year. Where RD process provides the lowest capital cost, operating cost, equipment cost, and installed cost compared to batch and PFR processes according to APEA. Obtained results from production of trivalerate can be used to evaluate the economic and technical feasibility of a continuous production plant for pentaerythritol tetravalerate (PETV). Where initial simulations show a good economic and technical viability of a continuous ester production plant.

Orientador: Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:34:50Z (GMT). No. of bitstreams: 1 Maia_JulioPereira_D.pdf: 8705466 bytes, checksum: e604d7a471ca19eb99492912d431174b (MD5) Previous issue date: 2013 / Resumo: Esta tese apresenta um estudo de estratégias de esquemas de controle em unidades de destilação a vácuo de refinarias de petróleo, com o uso de dados e informações de uma refinaria brasileira, de modo a se desenvolver uma simulação representativa do processo, onde uma diferença global máxima de 5% entre os resultados de simulação e os dados de saída reais foi obtida. A simulação foi executada com alto nível de detalhamento, com cálculos de queda de pressão, dimensionamento de sistemas de bombeamento e uso de internos de coluna comerciais. Uma análise paramétrica foi executada para a verificação das variáveis mais influentes do processo. A simulação em estado estacionário resultante foi então convertida para o regime dinâmico, onde um esquema de controle equivalente ao esquema de controle da planta real foi implementado. Este esquema de controle foi submetido a um conjunto de perturbações usuais ao processo real, produzindo respostas dinâmicas do processo para cada perturbação aplicada. Pela análise das dinâmicas destas respostas e das respostas do sistema em malha aberta, um esquema de controle alternativo foi proposto e verificado da mesma maneira que o esquema de controle equivalente. Malhas de controle específicas para quantificar a qualidade dos produtos, tendo por base o índice ASTM D86 foram inseridas. A comparação entre os dois esquemas de controle por meio das respostas dinâmicas na qualidade dos produtos, considerando como parâmetro o ISE (Integral Squared Error) das malhas de cada esquema para comparação, apresentou uma redução média do erro em 70% na qualidade dos produtos principais / Abstract: A petroleum vacuum distillation unit study on control scheme strategies is developed in this work. Real plant data and information is gathered from a Brazilian Refinery to develop a representative simulation of the process, which had achieved a maximum 5% overall difference from the plant results. The simulation was set to be highly detailed, including pressure drop calculations, pumping system and the use of commercial column internals (packing and plates) in it. A parametric analysis was carried in order to verify the most influent variables in the process, with respect to temperature profiles, product flows and product qualities. The resultant steady state simulation was then converted into dynamic regime, when a control scheme equivalent to the real plant control scheme was implemented. This control scheme was then subjected to a set of common perturbations that occur in the real process, producing the dynamic response of the process to each perturbation applied. By analyzing the dynamics of these responses and the open loop responses, an alternative control scheme is proposed and verified in the same manner the later one was. A specific control loop was proposed to account a petroleum product quality index, such as ASTM D86 95% recovery. The comparison of the control schemes by means of the dynamic responses considering the correlated ISE (integral squared error) of each scheme has shown an average error reduction of 70% in the main products quality / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Le développement du bois énergie est un des principaux leviers dans la lutte contre le changement climatique. Cependant son utilisation à grande échelle n’est pas sans risque pour l’environnement. Afin de quantifier les impacts environnementaux de la filière bois énergie, nous avons, dans un premier temps, développé un modèle systémique de la filière, depuis la forêt jusqu’à la production d’énergie. Deux technologies ont été considérées pour la co-production d’électricité et de chaleur à partir de biomasse forestière : l’une, traditionnelle, par combustion directe, et l’autre, plus avancée mais moins mature, par gazéification. Dans le cas de la gazéification, nous avons défini les conditions opératoires les plus favorables du procédé en tenant compte des rendements énergétiques et exergétiques ainsi que de la qualité du syngas. Dans un deuxième temps, nous avons calculé les flux de carbone et de minéraux exportés lors de la récolte du bois ainsi que le nombre d’hectares requis, puis les ressources et rejets liées au fonctionnement des centrales biomasses. Nous avons noté qu’une intensification des pratiques sylvicoles résultait en une augmentation des exportations de minéraux. Enfin, nous avons évalué les performances environnementales des deux filières à l’aide d’une Analyse de Cycle de Vie (ACV). Dans le contexte énergétique français, les deux systèmes offrent des performances très similaires, avec un léger avantage à la combustion. Du point de vue du changement climatique, il serait plus particulièrement bénéfique de développer ces procédés biomasse afin de remplacer les technologies de production d’énergie basées sur les combustibles fossiles / Biomass is one of the most promising renewable energy source in Europe. Its use as a substitute to fossil energy is expected to mitigate climate change. However, potential drawbacks are also feared with large scale development. In order to assess the environmental impacts of the biomass-to-energy chain, we firstly developed a model of the bioenergy system, from the forest to the energy production. We focused on two biomass power plants for combined heat and power (CHP) production: one is based on the conventional direct combustion process while the other is based on the more advanced gasification process. Gasification offers higher electrical efficiency, but its development is still facing technical difficulties. In case of the gasification process, we defined the best operating conditions regarding energetic and exergetic efficiencies, as well as the syngas quality requirements. Secondly, we calculated the carbon and mineral flows taken from the forest through energy wood harvesting, along with the forested area required to feed the CHP plant. The other resources and emissions related to the plant operation were also predicted. We observed that more extensive forestry practices led to an increase in the mineral exports. Finally, we evaluated the environmental performance of the two biomass CHP plants using life cycle assessment (LCA). Within French energy context, we found that both CHP technologies had very similar impacts with a slight advantage toward the combustion process. It appears of particular benefit to replace current fossil energy systems with biomass CHP plants to reduce climate change

Ce travail de recherche porte sur la modélisation mathématique des principaux procédés sidérurgiques en suivant une approche systémique. L’objectif est d’élaborer un outil de modélisation de l’ensemble de la filière destiné à l’optimiser du point de vue énergétique et environnemental. Nous avons développé des modèles physico-chimiques du haut fourneau, de la cokerie, de l’agglomération et du convertisseur. Ces modèles ont ensuite été reliés entre eux sous forme d’un diagramme de flux unique en utilisant le logiciel ASPEN Plus. Dans une première partie, nous nous sommes particulièrement intéressés au haut fourneau à recyclage, une variante innovante du haut fourneau dans laquelle les gaz de gueulard sont recyclés et réinjectés aux tuyères après capture du CO2. Nous avons testé une réinjection à un niveau (aux tuyères) et à deux niveaux (tuyères et ventre). Les résultats ont été comparés avec succès à des données expérimentales issues d’un réacteur pilote et montrent que le recyclage permet une baisse de plus de 20 % des émissions de CO2 du haut fourneau. Le recyclage à deux niveaux ne semble pas plus performant que celui à un seul niveau. Dans un deuxième temps, nous avons simulé le fonctionnement d’une usine sidérurgique intégrée dans son ensemble. Différentes configurations ont été testées, pour un haut fourneau classique ou un haut fourneau à recyclage, en considérant un éventuel recyclage du laitier de convertisseur à l’agglomération, et en étudiant l’influence de la teneur en silicium de la fonte sur toute la filière. On montre notamment qu’il est possible de réduire le prix de revient de la tonne d’acier en substituant et recyclant différents sous-produits / This research study deals with mathematical modeling of the main steelmaking processes following a systems approach. The objective was to build a modeling tool of the whole steelmaking route devoted to its energetic and environmental optimization. We developed physical-chemical models for the blast furnace, the coke oven, the sintering plant and the basic oxygen furnace. These models were then linked together in a single flow sheet using the ASPEN Plus software. First, we focused on the top gas recycling blast furnace, a novel variant of the blast furnace in which the top gas is recycled and re-injected into the tuyeres after CO2 removal and capture. We tested both a reinjection at one level (tuyeres only) and at two levels (tuyeres and shaft). The results were successfully compared with experimental data from a pilot reactor and demonstrate that recycling can lower the blast furnace CO2 emissions by more than 20%. Recycling at two levels does not seem more efficient than at a single level. Second, we simulated the operation of an entire integrated steelmaking plant. Different configurations were tested, using a conventional blast furnace or a top gas recycling blast furnace, considering a possible recycling of the converter slag to the sintering plant, and studying the influence of Si content in the hot metal on the entire steelmaking plant operation. We show that it is possible to reduce the cost of producing steel by substituting and recycling various by-products

The waste heat recovery technologies have become very relevant since many industrial plants continuously reject large amounts of thermal energy during normal operation which contributes to the increase of the production costs and also impacts the environment. The simulation programs used in industrial engineering enable development and optimization of the operational processes in a cost-effective way. The company Chematur Engineering AB, which supplies chemical plants in many different fields of use on a worldwide basis, was interested in the investigation of the possibilities for effective waste heat recovery from the hydrogenation of dinitrotoluene, which is a sub-process in the toluene diisocyanate manufacture plant. The project objective was to implement waste heat recovery by application of the Organic Rankine Cycle and the Absorption Refrigeration Cycle technologies. Modeling and design of the Organic Rankine Cycle and the Absorption Refrigeration Cycle systems was performed by using Aspen Plus® simulation software where the waste heat carrier was represented by hot water, coming from the internal cooling system in the hydrogenation process. Among the working fluids investigated were ammonia, butane, isobutane, propane, R-123, R-134a, R-227ea, R-245fa, and ammonia-water and LiBr-water working pairs. The simulations have been performed for different plant capacities with different temperatures of the hydrogenation process. The results show that the application of the Organic Rankine Cycle technology is the most feasible solution where the use of ammonia, R-123, R-245fa and butane as the working fluids is beneficial with regards to power production and pay-off time, while R-245fa and butane are the most sustainable choices considering the environment.

The objective of this study is to evaluate and compare, both technically and economically, various glucose feeding concentrations and different redox potential settings on ethanol production under very-high-gravity (VHG) conditions. Laboratory data were collected for process modeling and two process models were created by two individual process simulators. The first one is a simplified model created and evaluated by Superpro Designer. The second one is an accurate model created by Aspen Plus and evaluated by Aspen Icarus Process Evaluator (Aspen IPE). The simulation results of the two models were also compared. Results showed that glucose feeding concentration at 250±3.95 g/L to the fermentor resulted in the lowest unit production cost (1.479 $/kg ethanol in the Superpro model, 0.764 $/kg ethanol in the Aspen Plus model), with redox potential control effects accounted. Controlling redox potential at -150 mV increased the ethanol yield under VHG fermentation conditions while no significant influences were observed when glucose feeding concentration was less than 250 g/L. Results of product sales analysis indicated that for an ethanol plant with a production rate of 85~130 million kg ethanol/year, only maintaining the glucose feeding concentration to the fermentor at around 250 g/L resulted in the shortest payout period of 5.33 years in average,, with or without redox potential control. If 300±6.42 g/L glucose feeding concentration to the fermentor is applied, it is essential to have the redox potential only controlled at -150 mV in the fermentor to limit the process payout period within 6 years. In addition, fermentation processes with glucose feeding concentration at around 200 g/L to the fermentor were estimated to be unprofitable under all studied conditions. For environmental concerns, two disposal alternatives were presented for CO2 produced during fermentation process rather than emission into atmosphere. One is to sell CO2 as byproduct, which brought 1.52 million $/year income for an ethanol plant with a capacity of 100 million kg ethanol/year. Another option is to capture and transport CO2 to deep injection sites for geological underground storage, which is already a safe and mature technology in North America, and also applicable to many other sites around the world. This would roughly add 4.78 million dollars processing cost annually in the studied scenario. Deep injection of captured CO2 from ethanol plants prevents emission of CO2 into the atmosphere, thus makes it environmental friendly.

The objective of this study is to evaluate and compare, both technically and economically, various glucose feeding concentrations and different redox potential settings on ethanol production under very-high-gravity (VHG) conditions. Laboratory data were collected for process modeling and two process models were created by two individual process simulators. The first one is a simplified model created and evaluated by Superpro Designer. The second one is an accurate model created by Aspen Plus and evaluated by Aspen Icarus Process Evaluator (Aspen IPE). The simulation results of the two models were also compared. Results showed that glucose feeding concentration at 250±3.95 g/L to the fermentor resulted in the lowest unit production cost (1.479 $/kg ethanol in the Superpro model, 0.764 $/kg ethanol in the Aspen Plus model), with redox potential control effects accounted. Controlling redox potential at -150 mV increased the ethanol yield under VHG fermentation conditions while no significant influences were observed when glucose feeding concentration was less than 250 g/L. Results of product sales analysis indicated that for an ethanol plant with a production rate of 85~130 million kg ethanol/year, only maintaining the glucose feeding concentration to the fermentor at around 250 g/L resulted in the shortest payout period of 5.33 years in average,, with or without redox potential control. If 300±6.42 g/L glucose feeding concentration to the fermentor is applied, it is essential to have the redox potential only controlled at -150 mV in the fermentor to limit the process payout period within 6 years. In addition, fermentation processes with glucose feeding concentration at around 200 g/L to the fermentor were estimated to be unprofitable under all studied conditions. For environmental concerns, two disposal alternatives were presented for CO2 produced during fermentation process rather than emission into atmosphere. One is to sell CO2 as byproduct, which brought 1.52 million $/year income for an ethanol plant with a capacity of 100 million kg ethanol/year. Another option is to capture and transport CO2 to deep injection sites for geological underground storage, which is already a safe and mature technology in North America, and also applicable to many other sites around the world. This would roughly add 4.78 million dollars processing cost annually in the studied scenario. Deep injection of captured CO2 from ethanol plants prevents emission of CO2 into the atmosphere, thus makes it environmental friendly.

Les risques sont inhérents à l’activité industrielle. Les prévoir et les maîtriser sont essentiels pour la conception et la conduite en sécurité des procédés. La réglementation des risques majeurs impose aux exploitants la réalisation d’études de sécurité quantitatives. La stratégie de maîtrise des risques repose sur la pertinence des analyses de risques. En marche dégradée, la dynamique des événements est déterminante pour quantifier les risques. Toutefois, de nos jours cette connaissance est difficilement accessible. Ce travail propose une méthodologie d’analyse de risques quantitative qui combine la méthode HAZOP, le retour d’expérience et la simulation dynamique de dérives de procédés. Elle repose sur quatre grandes étapes : La première étape est l’étude du fonctionnement normal du procédé. Pour cela, le procédé est décrit de façon détaillée. Des études complémentaires de caractérisation des produits et du milieu réactionnel sont menées si nécessaires. Ensuite, le procédé est simulé dynamiquement en fonctionnement normal. Lors de la seconde étape, parmi les dérives définies par l’HAZOP et le retour d’expérience, l’analyste discrimine celles dont les conséquences ne sont pas prévisibles et/ou nécessitent d’être quantifiées. La troisième phase fournit une quantification du risque sur la base de la simulation dynamique des scenarii retenus. Lors de la dernière étape, des mesures de maîtrise des risques sont définies et ajoutées au procédé lorsque le niveau de risque est supérieur au risque tolérable. Le risque résiduel est ensuite calculé jusqu’à l’atteinte de la cible sécurité. Le logiciel Aspen Plus Dynamics est sélectionné. Trois études de cas sont choisies pour démontrer d’une part, la faisabilité de la méthodologie et d’autre part, la diversité de son champ d’application : · la première étude de cas porte sur un réacteur semi-continu siège d’une réaction exothermique. L’oxydation du thiosulfate de sodium par le peroxyde d’hydrogène est choisie. Ce cas relativement simple permet d’illustrer la diversité des causes pouvant être simulées (erreur procédurale, défaut matériel, contamination de produits, …) et la possibilité d’étudier des dérives simultanées (perte de refroidissement du milieu et sous dimensionnement de la soupape de sécurité). · le deuxième cas concerne un réacteur semi-batch dans lequel une réaction exothermique de sulfonation est opérée. Elle est particulièrement difficile à mettre en œuvre car le risque d’emballement thermique est élevé. Cette étude montre l’intérêt de notre approche dans la définition des conditions opératoires pour la conduite en sécurité. · le troisième cas d’étude porte sur un procédé continu de fabrication du propylène glycol composé d’un réacteur et de deux colonnes de distillation en série. L’objectif est ici d’étudier la propagation de dérives le long du procédé. Sur la base du retour d’expérience, deux dérives au niveau du rebouilleur de la première colonne sont étudiées et illustrent les risques de pleurage et d’engorgement. La simulation dynamique illustre la propagation d’une dérive et ses conséquences sur la colonne suivante.

Biomass to Liquids via Fischer-Tropsch synthesis (BTL-FT) is regarded as one of the most promising routes for providing alternative solution to growing demand for energy and environmental protection. In Chapter I, the development and key issues of BTL-FT process (especially Fischer-Tropsch synthesis) were reviewed and identified. In Chapter II, Mo/HZSM-5 catalyst was synthesized using Incipient Wetness Impregnation method and tested in nitrogen rich model bio-syngas. Different operation parameters (temperature, pressure, and GHSV) were tested to investigate their influence on the catalytic performance. Those parameters were found to affect the performance significantly. Liquid samples from conversion were mainly composed of C8 to C10 range hydrocarbons. The catalyst characterization revealed that molybdenum species were well distributed on the catalyst support, while dealumination, agglomeration and coke deposition were observed in spent catalyst. The top layer of the spent catalyst had the most coke deposition. A Three-Dimensionally Ordered Macro-porous (3DOM) Fe based Fischer-Tropsch catalyst was developed using a facile in-situ Nitrate Oxidation-PMMA templating technique in Chapter III. Several techniques (including SEM, BET, TPR, HRTEM, XRD, XPS, and DRIFTS) were combined to characterize the morphology, textural properties and microstructures of 3DOM Fe catalysts at different stages. The effects of bio-syngas composition on carbonaceous species formation, iron phase transformation and catalytic performance were investigated and correlated. A novel hybrid bio-refinery process co-converting biomass and natural gas into liquid fuels via FTS with a CO2 recycle loop was developed, modeled and simulated by using Aspen Plus in Chapter IV. The Aspen Plus model utilized experimental data from the 3DOM Fe catalyst. Economic analysis was performed on different scenarios based on the simulation results to determine profitability of the process. Results indicated that 102.65 t/h gasoline and 22.93 t/h diesel can be produced with the co-processing of 100.00 t/h biomass and 112.3 t/h natural gas using 307.78 t/h of recycled CO2 in the process simulation. The carbon conversion rate was estimated to be 81.23% for the hybrid process. Economic analysis revealed that the process can be profitable when using at least 10.00 t/h biomass and 11.23 t/h natural gas.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Data on the process performance at different operating conditions are required to determine the feasibility of a separation process. Such data can be experimentally measured, but due to the time and costs associated with pilot plant scale experiments, the use of predictive process models are often preferred. The main aim of this project is to establish a working process model in Aspen Plus® that can be used to predict the separation performance of a supercritical fluid fractionation process aimed at the separation of mixtures of detergent range alkanes and alcohol isomers where similar boiling points or low relative volatilities can occur. Currently, an azeotropic distillation process is employed for the separation of detergent range alkanes and alcohols. Although this process shows good separation performance, some concerns regarding the operating conditions are raised: the preferred entrainer, diethylene glycol, is toxic to humans; very low operating pressures of 0.016 – 0.031 MPa and high temperatures of 473 K are required; additional processing units and materials are required to remove the entrainer from the product streams. An alternative process, supercritical fluid fractionation, is proposed in this work after previous studies have reported that this process have potential for the separation of alkanes and alcohols. The supercritical fluid fractionation process addresses the concerns of the azeotropic distillation process in the following ways: a non-toxic solvent, CO2, is used as the separating agent; mild temperatures of 344 K is proposed, but at the cost of the low operating pressures of the azeotropic process; and a single process unit and no additional material is required to separate the solvent from the product streams. A process model was developed in Aspen Plus® to evaluate the separation performance of the newly proposed supercritical fluid fractionation process and compare it to the current azeotropic distillation process. The development of the process model included the development of an accurate thermodynamic model in Aspen Plus®. After thorough evaluation of a number of cubic equations of state, the RK-ASPEN model was found to be superior in its representation and prediction of phase transition pressures for multi-component mixtures of detergent range alkanes and alcohols in the temperature range 318 – 348 K. Phase transition pressures could be predicted with an error of less than 6 % with the inclusion of regressed polar parameters and binary solute-solvent interaction parameters for two multi-component mixtures: CO2 + (20 % n-dodecane + 70 % 1-decanol + 10 % 3,7-dimethyl-1-octanol) and CO2 + (25 % n-decane + 25 % 1-decanol + 25 % 3,7-dimethyl-1-octanol + 25 % 2,6-dimethyl-2-octanol). Polar parameters were regressed from pure component vapour pressure data predicted with correlations available in Aspen Plus®. Binary interaction parameters were regressed from experimental bubble and dew point data. Binary bubble and dew point data were measured for a number of systems containing ethane or CO2 and a C10-alkane or C10-alcohol isomer at temperatures between 308 K and 353 K, and compositions ranging between 0.01 and 0.7 mass fraction solute. A comparison between the phase equilibrium data measured for these systems revealed that the structure of the molecule, and not only the molecular weight, influences its solubility in the supercritical solvent. The phase transition pressures of n-decane, 2-methylnonane, 3-methylnonane and 4-methylnonane did not differ significantly in CO2 or ethane, and these compounds will in all likelihood not be separated in a supercritical fluid fractionation process. The phase transition pressures measured for the C10-alcohol isomers decreased in both CO2 and ethane in the following order: 1-decanol, 3,7-dimethyl-1-octanol, 2-decanol, 2,6-dimethyl-2-octanol and 3,7-dimethyl-3-octanol. The position of the hydroxyl group and the number, length and position of the side branches, all influence the solubility behaviour and phase transition pressures of the isomeric alcohols in the supercritical solvent. Since the use of ethane did not show any significant benefits with regard to selectivity, the use of the less harmful and less expensive solvent, CO2, in further investigations was justified. The RK-ASPEN thermodynamic model, with the inclusion of the regressed polar and binary solute-solvent interaction parameters, was implemented in the process model and the separation performance of the process was simulated at different operating conditions for the CO2 + (25 % n-decane + 25 % 1-decanol + 25 % 3,7-dimethyl-1-octanol + 25 % 2,6-dimethyl-2-octanol) mixture. A comparison to experimental pilot plant data revealed that the model cannot be used to predict the separation performance at low fractionation temperatures (316 K) due to shortcomings in the thermodynamic model. However, the performance of the process at high fractionation temperatures (344 K) could be predicted well, with an error of 10 – 36 %. Simulations for the CO2 + (25 % n-decane + 25 % 1-decanol + 25 % 3,7-dimethyl-1-octanol + 25 % 2,6-dimethyl-2-octanol) and CO2 + (20 % n-dodecane + 70 % 1-decanol + 10 % 3,7-dimethyl-1-octanol) mixtures showed that the composition of the feed mixture have a significant effect on the location and size of the operating window and optimum operating conditions. The optimum operating conditions were defined as the conditions where an acceptable selectivity ratio and alcohol recovery occurred simultaneously. Since the selectivity ratio and alcohol recovery have opposing optimization approaches, a number of possible optimum operating conditions exist, based on the product specifications. When an alcohol and an alkane with similar phase behaviour exist in a mixture, a distinct minimum selectivity ratio will occur at a point within the extract-to-feed ratio limits of the process. When the alkanes and alcohols present in a mixture do not have similar or overlapping phase transition pressures, the minimum selectivity ratio will typically cover a small range of extract-to-feed ratios at the high end limit of the extract-to-feed ratio range. To summarize: A process model was established in Aspen Plus® that can be used to determine the feasibility and separation performance of a supercritical fractionation process for a feed mixture of detergent range alkane and alcohol isomers. The model was used to prove that an SFF process is a feasible alternative process to consider for the removal of alkanes from mixtures of detergent range alcohol isomers, even where overlapping boiling points or low relative volatilities occur. During the development of the process model, the following significant novel contributions were made: · New phase equilibrium data were measured for C10-alkane and C10-alcohol isomers in supercritical ethane, as published in The Journal of Supercritical Fluids 58 (2011) 330 – 342. · New phase equilibrium data were measured for C10-alkane and C10-alcohol isomers in supercritical CO2, as published in The Journal of Supercritical Fluids 59 (2011) 14 – 26. · A thermodynamic model was developed in Aspen Plus® that can accurately predict the phase transition pressures of binary, ternary and multi-component mixtures of detergent range alkanes and alcohols in supercritical CO2, as published in The Journal of Supercritical Fluids 84 (2013) 132 – 145. · A process model was developed in Aspen Plus® that can be used to predict the separation performance of a supercritical fluid fractionation process for the separation of mixtures of detergent range alkanes and alcohols. · Experimental and simulated results indicated that a supercritical fluid fractionation process can be implemented successfully to separate an alkane from a mixture of alcohol isomers, as was shown for two mixtures: CO2 + (25 % n-decane + 25 % 1-decanol + 25 % 3,7-dimethyl-1-octanol + 25 % 2,6-dimethyl-2-octanol) and CO2 + (20 % n-dodecane + 70 % 1-decanol + 10 % 3,7-dimethyl-1-octanol). / AFRIKAANSE OPSOMMING: Data oor die omvang van skeiding by verskillende bedryfstoestande word benodig om die lewensvatbaarheid van ’n skeidingsproses te bepaal. Sulke data kan eksperimenteel gemeet word, maar as gevolg van die tyd en kostes geassosieer met eksperimente op loodsaanlegskaal, word die gebruik van prosesmodelle verkies. Die hoofdoel van hierdie projek is om ’n werkende prosesmodel, wat daarop gemik is om C8 – C20 alkane en alkohol isomere te skei, in Aspen Plus® tot stand te bring om die omvang van die skeiding van ’n superkritiese fraksioneringsproses te meet. Tans word azeotropiese distillasie gebruik vir die skeiding van C8 – C20 alkane en alkoholisomere. Alhoewel goeie skeiding met hierdie proses bewerkstellig word, is daar sekere eienskappe van die proses wat aandag vereis: die voorgestelde skeidingsagent, dietileen glikol, is giftig vir mense; baie lae bedryfsdrukke van 0.016 – 0.031 MPa en hoë temperature van 473 K word benodig; addisionele proseseenhede en materiaal is nodig om die skeidingsagent van die produkte te verwyder. Die gebruik van ’n alternatiewe proses - superkritiese fraksionering - word in hierdie werk voorgestel nadat vorige studies getoon het dat hierdie proses die potensiaal het om alkane en alkohole te skei. Die superkritiese fraksioneringsproses spreek al die kommerwekkende eienskappe van azeotropiese distillasie aan soos volg: ’n veilige oplosmiddel, CO2, word as die skeidingsagent gebruik; gemiddelde temperature van 344 K word voorgestel, maar ten koste van lae bedryfsdrukke; ’n enkele proseseenheid en geen addisionele materiaal word benodig om die oplosmiddel van die produkte te skei nie. ’n Prosesmodel is in Aspen Plus® ontwikkel om die omvang van die skeiding wat deur die voorgestelde superkritiese fraksioneringsproses teweeggebring is, te evalueer en te vergelyk met die azeotropiese distillasieproses wat tans in gebruik is. Die ontwikkeling van die prosesmodel sluit die ontwikkeling van ’n akkurate termodinamiese model in Aspen Plus® in. Na deeglike evaluasie van ’n aantal kubiese toestandsvergelykings is gevind dat die RK-ASPEN-model die faseoorgangsdrukke van multi-komponentmengsels van C8 – C20 alkane en alkohole die beste voorspel binne die temperatuurbereik van 318 – 348 K. Faseoorgangsdrukke kon voorspel word met ’n fout van minder as 6 % met die insluiting van voorafbepaalde polêre parameters en binêre interaksie-parameters vir twee multi-komponentmengsels: CO2 + (20 % n-dodekaan + 70 % 1-dekanol + 10 % 3,7-dimetiel-1-oktanol) and CO2 + (25 % n-dekaan + 25 % 1-dekanol + 25 % 3,7-dimetiel-1-oktanol + 25 % 2,6-dimetiel-2-oktanol). Polêre parameters is bepaal met dampdruk data, wat voorspel is met korrelasies in Aspen Plus®. Binêre interaksieparameters is van eksperimentele faseoorgangsdata bepaal. Binêre faseoorgangsdata is vir ’n aantal sisteme wat uit etaan of CO2 en ’n C10-alkaan- of C10-alkohol-isomeer bestaan, gemeet by temperature tussen 308 K en 353 K en samestellings van tussen 0.01 en 0.7 massafraksie van die opgeloste stof. ’n Vergelyking tussen die gemete fase-ewewigsdata het onthul dat die struktuur van die molekuul, en nie net die molekulêre massa nie, die oplosbaarheid van die stof in die superkritiese oplosmiddel beïnvloed. Die faseoorgangsdrukke van n-dekaan, 2-metielnonaan, 3-metielnonaan en 4-metielnonaan het geen skynbare verskille getoon in etaan of CO2 nie en dus sal hierdie stowwe in alle waarkynlikheid nie met ’n superkritiese fraksioneringsproses geskei kan word nie. Die faseoorgangsdrukke wat vir die C10-alkohol gemeet is, het in beide etaan en CO2 afgeneem in die volgende volgorde: 1-dekanol, 3,7-dimetiel-1-oktanol, 2-dekanol, 2,6-dimetiel-2-oktanol en 3,7-dimetiel-3-oktanol. Die posisie van die hidroksielgroep en die aantal, lengte en posisie van die sytakke beïnvloed die oplosbaarheidsgedrag van die alkohol-isomere in die superkritiese oplosmiddel. Aangesien die gebruik van etaan nie enige voordele ten opsigte van selektiwiteit inhou nie, is die gebruik van die minder skadelike en goedkoper oplosmiddel, CO2, vir verdere ondersoeke geregverdig. Die ontwikkelde termodinamiese model, met die insluiting van die polêre parameters en binêre interaksieparameters, is in die prosesmodel ingesluit en die omvang van die skeiding van die proses is gesimuleer by verskillende bedryfstoestande vir die CO2 + (25 % n-dekaan + 25 % 1-dekanol + 25 % 3,7-dimetiel-1-oktanol + 25 % 2,6-dimetiel-2-oktanol) mengsel. ’n Vergelyking tussen die gesimuleerde data en die eksperimentele loodsaanlegdata het onthul dat die model nie die omvang van die skeiding kan voorspel by lae fraksioneringstemperature (316 K) nie as gevolg van die tekortkominge in die termodinamiese model. Die omvang van die skeiding by hoë temperature (344 K) kon egter goed voorspel word met ’n fout van 10 – 36 %. Simulasies van die CO2 + (25 % n-dekaan + 25 % 1-dekanol + 25 % 3,7-dimetiel-1-oktanol + 25 % 2,6-dimetiel-2-oktanol) en CO2 + (20 % n-dodekaan + 70 % 1-dekanol + 10 % 3,7-dimetiel-1-oktanol) mengsels het getoon dat die samestelling van die voermengsel ’n beduidende effek op die grootte van die bedryfsvenster en optimum bedryfstoestande het. Die optimum bedryfstoestande word gedefinieer as die toestande waar ’n aanvaarbare selektiwiteitsverhouding en alkoholherwinning terselfdertyd voorkom. Aangesien die selektiwiteitsverhouding en alkoholherwinning teenstrydige optimeringsbenaderings het, bestaan daar ’n aantal optimum bedryfstoestande gebaseer op die produkspesifikasies. Wanneer ’n alkohol en ’n alkaan met ooreenstemmende fasegedrag saam in ’n mengsel voorkom, bestaan daar ’n duidelike minimum selektiwiteitsverhouding by ’n punt binne die ekstrak-tot-voer-verhoudingslimiete van die proses. Wanneer die alkane en alkohole in ’n mengsel nie ooreenstemmende fasegedrag toon nie, sal die minimum selektiwiteitsverhouding oor ’n reeks ekstrak-tot-voer-verhoudings voorkom, tipies by die hoë limiet van die ekstrak-tot-voer-verhoudingsreeks. Om op te som: ’n Prosesmodel is in Aspen Plus® tot stand gebring wat die lewensvatbaarheid en omvang van die moontlike skeiding van ’n superkritiese fraksioneringsproses vir voermengsels van C8 – C20 alkane en alkohol-isomere kan voorspel. Die model is gebruik om te bewys dat ’n superkritiese proses ’n lewensvatbare alternatiewe proses is om te oorweeg vir die verwydering van alkane uit mengsels van alkohol-isomere, self waar ooreenstemmende kookpunte of lae relatiewe vlugtigheid tussen komponente voorkom. Tydens die ontwikkeling van die prosesmodel is die volgende beduidende nuwe bydraes gemaak: · Nuwe fase-ewewigsdata is gemeet vir C10-alkaan- en C10-alkohol-isomere in superkritiese etaan, soos gepubliseer in The Journal of Supercritical Fluids 58 (2011) 330 – 342. · Nuwe fase-ewewigsdata is gemeet vir C10-alkaan and C10-alkohol isomere in superkritiese CO2, soos gepubliseer in The Journal of Supercritical Fluids 59 (2011) 14 – 26. · ’n Termodinamiese model is ontwikkel in Aspen Plus® wat die faseoorgangsdrukke van binêre, ternêre en multi-komponent mengsels van C8 – C20 alkane en alkohol-isomere in superkritiese CO2 akkuraat kan voorspel, soos gepubliseer in The Journal of Supercritical Fluids 84 (2013) 132 – 145. · ’n Prosesmodel is ontwikkel in Aspen Plus® wat die omvang van die moontlike skeiding van ’n superkritiese fraksioneringsproses, gemik op die skeiding van mengsels van C8 – C20 alkane en alkohol-isomere, kan voorspel. · Eksperimentele en gesimuleerde resultate toon aan dat ’n superkritiese fraksioneringsproses suksesvol geïmplementeer kan word vir die skeiding van ’n alkaan vanuit ’n mengsel van alkohol-isomere, soos bewys vir twee mengsels: CO2 + (25 % n-dekaan + 25 % 1-dekanol + 25 % 3,7-dimetiel-1-oktanol + 25 % 2,6-dimetiel-2-oktanol) en CO2 + (20 % n-dodekaan + 70 % 1-dekanol + 10 % 3,7-dimetiel-1-oktanol).