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Reactive distillation has enormous potential for the economical synthesis of tertiary ethers. Methyl tert-butyl ether (MTBE) has been commercially produced with this technology since the early 1980s and it appears that the process also has application for Ethyl tert-butyl ether (ETBE) and other ethers. However, the combination of reaction and distillation in a single unit operation produces a process complexity that inhibits expeditious design and tight control, and presents a technology risk for potential developers. This particularly applies to hybrid reactive distillation where both reactive and non-reactive column sections are employed.The steady state simulation of a series of reactive distillation columns and processes for the production of ETBE and MTBE illuminated a number of important issues related to the optimal design techniques. Many of these issues are peculiar to reactive distillation and would not reasonably be anticipated without a priori knowledge of the phenomena involved. For example, the addition of theoretical equilibrium stages and an increase in the reflux ratio do not always have a directionally equivalent effect. The trade-off between energy consumption and capital cost which is the basis for most distillation designs cannot always be applied to reactive distillation. Importantly, the use of standard modelling techniques for equilibrium processes was also validated for reactive distillation design.The use of residue curve diagrams and reactive residue curve diagrams for the design of reactive distillation processes was investigated and shown to provide useful information regarding the feasibility of reaction-separations. Combined with simulation tools (e.g. Pro/II and SpeedUp), these techniques form the basis of a proposed design strategy for hybrid reactive distillation. It is important to apply these design tools appropriately and to ++ / select the correct process for a given application. The optimal design must also consider economics and the relative values of products, reactants and energy. These issues were studied with respect to ETBE production for gasoline oxygenation.The complexity of hybrid reactive distillation not only presents design challenges but potentially makes the process more difficult to control. Dynamic simulations of ETBE and MTBE reactive distillation processes were used to explore some unusual dynamic phenomena and to elucidate the process non-linearity and bidirectionality of reactive distillation. The presence of multiple steady states for some reactive distillation columns has been documented previously but the analysis of this behaviour has been incomplete and somewhat flawed. It was shown that the distinction between molar inputs and physically realisable mass or volumetric inputs is crucial and that multiplicity could be present in one case and not in the other. Multiplicity that is only observed with molar inputs (relatively common) was termed pseudo-multiplicity. Pseudo-multiplicity has few implications for the operation and control of practical reactive distillation processes although most literature examples of multiple steady states fall into this category. Four distinct causes of output multiplicity were identified including one new cause, reaction hysteresis, which is only applicable to hybrid reactive distillation. It was shown, using dynamic simulations, that transitions between parallel steady states are possible for a range of physically realisable and practical disturbances. This contrasts with other work in the area, which examines only unrealisable events and control schemes.An extensive analysis of reactive distillation control was also undertaken with respect to ETBE and MTBE hybrid columns. Manual (open-loop) control was shown to be impractical due to ++ / the need to sustain the operating conditions at close to the optimal values in order to produce acceptable process performance. One-point composition control was found to be relatively easy to implement and effective with either an energy-balance or a material-balance control scheme provided only one steady state was present. Where multiple steady states exist, there are restrictions on the feasible control structures due to unavoidable instability in the inventory controllers. For example, if multiple steady states exist for the one value of the reboiler duty, only the bottoms product draw rate can be used to control the reboiler sump level. Thus, a material-balance control structure that uses the reboiler duty to control the sump level cannot be implemented in practice. Two-point control was also investigated and found to effectively prevent transitions between parallel steady states. Although more complex and difficult to implement than one-point control, a two-point scheme could be used successfully to control both the product composition and the reactant conversion and this could be desirable in some cases.A reactive distillation pilot plant was designed and operated for ETBE synthesis from ethanol and a locally available refinery hydrocarbon stream. The design of the pilot plant was based on simulation studies and the objective of operating in the industrially significant ranges of product purity and isobutene conversion. A fully automatic control system was designed and installed on the pilot plant to permit precise control of the manipulated variables and the framework to implement a range of control structures and schemes.Keywords: reactive distillation; process simulation; process design; process control; dynamic simulation; multiplicity; bidirectionality; distillation control; inferential control; pilot plant design and operation.

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Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T21:48:52Z (GMT). No. of bitstreams: 1 Winter_Alessandra_M.pdf: 1498368 bytes, checksum: d1d4e8f4e6ae77f7e8b03de75e95568d (MD5) Previous issue date: 2007 / Resumo: No Brasil, grandes reservas de petróleo encontradas são de óleos pesados. As altas viscosidades destes óleos dificultam a exploração, escoamento, transferência, processamento primário e refino. Se por um lado, a realidade brasileira de óleos pesados é grande, por outro, a necessidade por produtos mais leves na indústria petrolífera vem aumentando e isto exige novos desenvolvimentos, de forma a agregar valor a estes produtos. Dentro deste contexto, a presente dissertação de mestrado tem como objetivo geral o desenvolvimento de metodologia para caracterização de frações ultra pesadas de petróleo nacional através da tecnologia de destilação molecular. Para atingir este objetivo, foram realizadas as seguintes etapas: familiarização com o processo de destilação molecular, incluindo experimentos com óleos lubrificantes, a fim de se estabelecer metodologia robusta para o funcionamento do equipamento; condução dos experimentos com dois tipos de resíduos de petróleo utilizando o destilador molecular de filme descendente, obtendo-se as frações ultra pesadas; caracterização dos destilados e resíduos (frações ultra pesadas) do processo de destilação molecular por diferentes métodos analíticos e determinação da curva de destilação (porcentagem em massa da corrente de destilado em função da temperatura) a partir dos dados experimentais. Desta forma, a caracterização das frações ultra pesadas do petróleo geradas no destilador molecular representará um considerável avanço no sistema de análise destas frações que, como conseqüência imediata, trará um melhor aproveitamento do óleo cru, além de ganhos na qualidade do produto final / Abstract: In Brazil, large petroleum¿s reserves are of heavy oils. The high viscosity of these oils, complicates its exploration, flowing, transfer, primary processing and refining. If by one side, the Brazilian reality of heavy oils is large, in the other, the need for lighter products in industry is increasing and this demands new developments, adding value to these products. Within this context, this work has as objectives: development of a new methodology for heavy fraction characterizations of the national petroleum through the technology of molecular distillation. In order to meet these objectives, the following steps were carried out: familiarization with the molecular distillation process, including experiments with lubricants oils, conduction of experiments with two types of petroleum residue using the falling film molecular distiller, obtaining ultra heavy fractions (distillate and residue); characterization of distillates and residues, from different analytical methods and determination of the distillation curve (mass percentage of distillate in function of temperature). So, the characterization of petroleum heavy fractions generated from the molecular distiller will represent a considerable advance in the analyses of these fractions and, as an immediate consequence, it will upgrade the crude oil, besides the quality gain in the final product / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Bibliography: leaves 118-127.

Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016. / The water desalination process needs large quantities of energy, either directly from fossil fuel or electricity from the national grid. However, these sources of energy significantly contribute to problems such as global warming in addition to creating a drain on the economy, due to their high cost. This dissertation is a description of the research undertaken with the aim of producing a water desalination prototype; a novel approach that was designed using state-of-the-art solar water heating equipment, incorporating the technologies of evacuated tubes and heat pipes. During the execution of the project, various modifications to the original commercially-available solar water heating system were attempted, each aimed at increasing the production of pure water. Finally, the system proved capable of producing a reasonable amount of pure water after twelve lengthy indoor experiments conducted in a laboratory in the department of Mechanical Engineering at the Cape Peninsula University of Technology, Bellville Campus, Cape Town, South Africa. Each experiment lasted five days on the basis of seven hours of exposure to an average amount of simulated solar radiation, followed by seventeen hours daily of inactivity and partial cooling down of the system.

Orientadores: Maria Regina Wolf Maciel, Rubens Maciel Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-28T09:05:54Z (GMT). No. of bitstreams: 1 CeronRodriguez_AstridLiliana_M.pdf: 3023609 bytes, checksum: d8c7bf657afb8875e9a6b75db8eed4f5 (MD5) Previous issue date: 2015 / Resumo: A metodologia da destilação molecular tem sido usada para caracterizar frações pesadas de petróleo, permitindo estender a curva de ponto de ebulição verdadeiro obtida pelos procedimentos padrão ASTM D 2892 e ASTM D 5236. Visando estabelecer uma metodologia que segue a estrutura das normas ASTM foi usada a correlação DESTMOL para corrigir a temperatura de operação do destilador molecular à temperatura atmosférica equivalente. A correlação foi testada com os diferentes petróleos trabalhados pelo grupo de pesquisa do LOPCA/LDPS/UNICAMP permitindo chegar até temperaturas próximas dos 700°C. Através de ferramentas computacionais foram calculadas as principais propriedades físico-químicas dos petróleos em estudo com a intenção de relacioná-las com os parâmetros do polinômio de terceiro grau que representa a curva PEV estendida. O ajuste de parâmetros foi feito empregando o algoritmo genético PIKAIA o que permitiu minimizar a porcentagem média de desvio absoluto %AAD. Finalmente empregando a Destilação Molecular foram destilados 5 resíduos de petróleo, os quais foram usados para testar o polinômio gerado / Abstract: Molecular Distillation Methodology has been used to characterize heavy oils, allowing the extension of the True Boiling Point (TBP) curve obtained with the ASTM D2892 and ASTM D5236 Standard procedures. In order to establish a methodology similar to an ASTM standard, a molecular distillation correlation (DESTMOL) was used to convert the operation temperature of the molecular distiller in an equivalent atmospheric temperature. This correlation was tested with different oils studied previously by the LOPCA/LDPS/UNICAMP research group, achieving temperatures up to 700°C. The main physicochemical properties of those oils were calculated with a computing tool, in order to correlate one or more properties with the polynomial coefficients that represents the extended TBP curve. The parameter adjustment was done with the PIKAIA genetic algorithm, minimizing the mean absolute deviation percentage (%AAD). Finally, 5 oil residues were distilled using the molecular distillation and their results were used to validate the polynomial previously calculated / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

Data-driven model predictive control framework of semicontinuous distillation process / Distillation technology is one of the most sought-after operations in the chemical process industries. Countless research has been done in the past to reduce the cost associated with distillation technology. As a result of process intensification, a semicontinuous distillation system is proposed as an alternative for purifying the n-component mixture (n>=3) which has the advantage over both batch and continuous process for low to medium production rates. A traditional distillation setup requires n-1 columns to separate the components to the desired purity. However, a semicontinuous system performs the same task by integrating a distillation column with n-2 middle vessel (storage tank). Consequently, with lower capital cost, the total annualized cost (TAC) per tonne of feed processed is less for a semicontinuous system compared to a traditional setup for low to medium throughput. Yet, the operating cost of a semicontinuous system exceed those of the conventional continuous setup. Semicontinuous system exhibits a non-linear dynamic behavior with a cyclic steady state and has three modes of operation. The main goal of this thesis is to reduce the operating cost per tonne of feed processed which leads to lower TAC per tonne of feed processed using a model predictive control (MPC) scheme compared to the existing PI configuration This work proposes a novel multi-model technique using subspace identification to identify a linear model for each mode of operation without attaining discontinuity. Subsequently, the developed multi-model framework was implemented in a shrinking horizon MPC architecture to reduce the TAC/tonne of feed processed while maintaining the desired product purities at the end of each cycle. The work uses Aspen Plus Dynamics simulation as a test bed to simulate the semicontinuous system and the shrinking horizon MPC scheme is formulated in MATLAB. VBA is used to communicate the inputs from MPC in MATLAB to the process in Aspen Plus Dynamics. / Thesis / Master of Science in Chemical Engineering (MSChE)

A waste acid stream is being produced by a local petrochemical company (SASOL) at a rate of 10 000 -12 000 tons per annum and contains approximately 44-mole % butyric acid, 20 % isobutyric acid and 10 % valeric acid. Whilst this stream is currently being incinerated, SASOL has requested an investigation into the possibility of separating and purifying butyric acid and isobutyric acid from this waste acid stream. The goal of this project was to determine a separation and purification route for butyric acid and isobutyric acid from SASOL'S waste acid stream. In order to achieve this, vacuum distillation and freeze crystallization were chosen for the recovery and purification of the acids respectively. Vapour-liquid equilibrium data for key component pairs present in the waste acid stream (propionic acid + butyric acid, isobutyric acid + butyric acid, butyric acid + isovaleric acid and butyric acid + hexanoic acid) were experimentally determined in a dynamic VLE still. The measured VLE data was successfully correlated us ing the gamma-phi approach. with the NRTL activity coefficient model representing the liquid phase and the virial equation of state describing the vapour phase. Using these equations. the VLE data obtained from the experimental work was then regressed to provide interaction coefficients for the NRTL model. which were then used in the Hysys process simulator to explore a range of design alternatives for distillation. Hysys simulations showed that greater than 80 % butyric acid and isobutyric acid can be recovered from the waste acid stream in a single distillation column containing 18 theoretical stages and an optimum reflux ratio of 3.8. The simulation was performed at a pressure of 58kPa and a maximum operating tempe rature of 150°C. Batch distillation experiments performed in a batch rectification column at 250kPa recovered more than 90% of both the butyric acid and isobutyric acid from a 450ml sample of the waste acid stream. A subsequent batch experiment concentrated the recovered acids into a distillate containing more than 95 % butyric acid and isobutyric acid combined. To investigate freeze crystallization as a suitable operation for purifying butyric acid and isobutyric acid a solid-liquid phase equilibrium curve for the system was generated us ing the Van Hoft equation. The generated curve showed that butyric acid and isobutyric acid could be theoretically purified (>98%) by operating two crystallizers at -20°C and -55°C respectively. A simple freeze crystallization experiment produced butyric acid with greater than 94% purity. An economic feasibility study conducted on the process showed that separation and purification of the acids by this process (distillation and crystallization) could create a business opportunity with revenue of approximately R47 million per annum. Preliminary estimates for capital investment amounted to approximately R5.4 million. for which the payback period was estimated at less than one year. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.