An important process-design problem in multicomponent separations is separation sequencing, which is concerned with the selection of the best method and sequence for a separation system. Essentially all of the published work on this subject has been limited to high-recovery or sharp separations, in which each component to be separated appears in one and only one product stream. In industrial practice, however, it is often useful to permit components that are being separated to appear in two or more product streams. This type of separation results in products that have overlapping components and is called nonsharp or sloppy separations. The present work proposes and demonstrates a simple and practical approach to the systematic synthesis of sloppy multicomponent separation sequences. The task of synthesizing sloppy multicomponent separation sequences is inherently more complicated than that of synthesizing sharp separation sequences as identification of infeasible splits and stream splitting, and transformation of infeasible product sets into equivalent feasible product sets are examples of some difficult tasks involved. A successful synthesis strategy calls for the development of an effective and flexible framework for representing the synthesis problem and for analyzing the feasibility of component splits. In this thesis, we propose a "component assignment diagram (CAD)" for problem representation. It is shown that the use of a CAD allows the design engineer to consider many alternative solutions (or sequences) and eliminate all infeasible component splits. Further, a "separation specification table (SST)" is proposed for feasibility analysis. In particular, the use of an SST provides a means to : (i) properly define and specify key and nonkey components; (ii) quickly identify feasible and infeasible splits; (iii) effectively deal with fuel products with unmatched compo- nent specifications; and (iv) systematically consider sloppy separations with multiple split points. One difficult problem arising from the design of multicomponent distillation columns for sloppy separations is to appropriately specify the distributions of non-key components in both overhead and bottoms products. Despite the importance of these specifications, there is very little information available on this subject in the literature. This thesis reports the results from a comparative study of rigorous simulation and shortcut modeling of multicomponent distillation columns for sloppy separations. One objective was to obtain improved quantitative understanding and practical design insights into the characteristics of nonkey distributions through a shortcut modeling based upon the Fenske equation. One method proposed in this work for synthesizing sloppy multicomponent products is a heuristic method that involves a two-phase approach. The first phase is concerned with the feasibility analysis of splits pertinent to a CAD with the aid of an SST. The second phase is to specify systematically a subsequent split by applying heuristics, an activity that involves the sequential application of several "rank-ordered" heuristics. A unifying approach is proposed and demonstrated for the synthesis of sloppy multicomponent product sets. Its objective is to generate equally good initial separation schemes, featuring as many as three characteristically different sequences, including all-sharp, all-sloppy, and both sharp and sloppy (i.e., mixed separation). The proposed methods have been applied to a number of industrial separation problems. The results show that the new methods offer an extremely useful means for design engineers to generate a number of good initial sequences for obtaining sloppy multicomponent product sets prior to the ultimate separator optimization and heat integration. / Ph. D.

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

Abstract not available

The use of carbon from fossil-based resources result in changes in the earth’s climate due to emissions of greenhouse gases. Biomass is the only renewable source of carbon that may be converted to transportation fuels and chemicals, markets now fully dominated by traditional oil supply. The biorefinery concept for upgrading and refinement of biomass feedstocks to value-added end-products has the potential to mitigate greenhouse gas emissions and replace fossil products. Most biorefineries use biochemical conversion processes and may have by-product streams suitable as feedstocks for thermal conversion and production of syngas. Further synthesis to value-added products from the syngas could increase the product output from the biorefinery. The application of thermal conversion processes integrated into an existing biorefinery concept has been evaluated in this licentiate thesis work. Two by-product streams; hydrolysis (lignin) residue from an ethanol plant and biogas from wastewater treatment, have been investigated as gasification/reforming feedstocks. Also, the pre-treatment method torrefaction has been evaluated for improved gasification fuel characteristics and integration aspects. A new process and system concept (Bio2Fuels) with potential carbon negative benefits has been suggested and evaluated as an alternative route for syngas production by separating biomass into a hydrogen rich gas and a carbon rich char product. The evaluation demonstrated that hydrolysis residue proved a suitable feedstock for gasification with respect to syngas composition. Biogas can be further reformed to syngas by combined biomass gasification and methane reforming, with promising results on CH4 conversion rate and increased H2/CO ratio at temperatures ≥1000°C. The pre-treatment method torrefaction was demonstrated to improve fuel qualities and may thus significantly facilitate entrained flow gasification of biomass residue streams. Also, integration of a torrefaction plant at a biorefinery site could make use of excess heat for drying the raw material before torrefaction. The Bio2Fuels concept was evaluated and found feasible for further studies. The application of thermal conversion processes into an existing biorefinery, making use of by-products and biomass residues as feedstocks, has significant potential for energy integration, increased product output as well as for climate change mitigation.

Thesis submitted in fulfilment of the requirements for the degree of Master of Technology: Chemical Engineering, In the Faculty of Engineering, Cape Peninsula University of Technology 2014 / Energy efficiency has become an important feature in the design of process plants due to the rising cost of energy and the more stringent environmental regulations being implemented worldwide. In South Africa as in other African countries, most of the chemical plants were built during the era of cheap energy with little emphasis placed on energy efficiency due to the abundance of cheap utility sources such as coal and crude oil. In most of these plants, there exists significant potential for substantial process heat recovery by conceptual integration of the plant’s heat exchangers. Pinch Technology (PT) has been demonstrated to be a simple and very effective technique for heat integration and process optimization. This study applies the PT approach to retrofit the heat exchangers network of the Crude Distillation Unit (CDU), of a complex petroleum refinery with the aim to reduce utilities requirement and the associated gaseous pollutants emission. This objective is accomplished by firstly conducting an energy audit of the unit to scope for potential energy saving. The existing Heat Exchanger Network (HEN) was re-designed using the remaining problem analysis (RPA) to achieve improved process energy recovery while making maximum use of the existing exchangers. The aim is to maintain the existing plant topology as much as possible. This network was later relaxed trading heat recovery with number of heat transfer unit so as to optimize the capital cost. These were implemented in AspenPlus v7.2 environment. The cost implications of the retrofitted and evolved networks including the capital and operating costs were determined on a 5 years payback time basis. The Problem Table (PT) analysis revealed that the minimum utilities requirements are 75 MW and 55 MW for the hot and cold utilities respectively. Compared to the existing utilities requirements of 103 MW for hot utility and 83 MW for cold utility, this represent a potential savings of about 26 % and 33 % savings for the hot and cold utilities respectively. The target utilities usage in the re-designed network after applying Remaining Problem Analysis (RPA) was found to be 55 MW for the cold utility and 75 MW for hot utility. The relaxed HEN required a cold utility of 62.5 MW and hot utility of 81 MW. From the total cost estimation, it was found that, although an energy saving of 34% can be achieved by the re-designed network before relaxation, the capital cost, US$ 1670000 is significantly higher than for the existing network (about US$ 980000). The final relaxed network gave an energy saving of 34% and with total cost of US$ 1100000. It was recommended from the study after cost comparisons of the four different networks (the original network, the MER network, the relaxed network and a grass-root design) that the best network for the retrofit purpose was the relaxed HEN, because there is no major shift in deviation from the topology of the original network. From the analysis it was found that a 34% saving in energy cost could be achieved from this retrofit. The Total Annual Cost (TAC) for this network gives credence to the fact that this retrofit which applied the rules of pinch analysis can bring about real saving in energy usage.

Orientadores: Rubens Maciel Filho, Caliane Bastos Borba Costa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-16T03:17:15Z (GMT). No. of bitstreams: 1 Gratiere_Ederson_M.pdf: 1433987 bytes, checksum: 0ad688b829ff34696ff6b641a96ae000 (MD5) Previous issue date: 2010 / Resumo: Este trabalho teve como objetivos principais avaliar o comportamento dinâmico de um cristalizador batelada operado por resfriamento, para o caso de estudo da cristalização de ácido adípico, de grande interesse industrial, e propor estruturas de controle para o mesmo. O trabalho é oportuno, uma vez que este tipo de processo é amplamente utilizado industrialmente, porém com baixo grau de automação, sendo utilizado muitas vezes o controle manual. Inicialmente foram realizadas simulações promovendo variações nas principais variáveis do processo, com a finalidade de analisar a dinâmica do mesmo. Posteriormente, foi desenvolvida uma estrutura de controle preditivo com matriz dinâmica (Dynamic Matrix Controller - DMC) com a finalidade de controlar a temperatura do cristalizador, manipulando a temperatura do fluido refrigerante que passa através de uma jaqueta. Esta estrutura de controle apresentou-se eficiente para o controle do cristalizador. Por fim foi desenvolvido um controlador DMC com o objetivo de controlar a supersaturação do sistema. Este controle exige a leitura em tempo real de duas variáveis do processo, temperatura e concentração do soluto em solução. Com essas duas variáveis é possível estimar a supersaturação do sistema em tempo real e compará-la com o setpoint. Para promover o controle da supersaturação é utilizada como variável manipulada a temperatura do fluido refrigerante. Esta estrutura de controle consegue promover maior repetibilidade para o sistema batelada e garante as mesmas condições de operação para todas as bateladas, gerando produtos mais uniformes, o que é bastante vantajoso. / Abstract: This study aimed to evaluate the dynamic behavior of a batch cooling crystallizer for the case of adipic acid crystallization, and to propose control structures for the system. This work is appropriate, since this type of process is widely used industrially, but with a low degree of automation, being often used the manual control. Initially simulations were carried out changing the process main variables, in order to analyze the dynamics of the process. In a second stage a control structure with predictive dynamic matrix controller (DMC) was developed in order to control the temperature of the crystallizer, manipulating the temperature of the refrigerant fluid passing through a jacket. This control structure was effective for the control of the crystallizer. Finally it a DMC controller with the objective of controlling the supersaturation of the system was developed. This control requires real-time aquisition of two process variables: temperature and concentration of solute in solution. With the two variables, it is possible to estimate the supersaturation of the system in real time and compare it with the setpoint. To promote the control of supersaturation the temperature of the refrigerant fluid is used as the manipulated variable. This control structure can promote greater repeatability for the batch system and provides the same operating conditions for all batches, producing more uniform products. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientadores: Maria Regina Wolf Maciel, Martin Aznar / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T22:03:29Z (GMT). No. of bitstreams: 1 Machado_AlexBarreto_M.pdf: 1251594 bytes, checksum: 12614335c44f56e98288ed9de32033db (MD5) Previous issue date: 2007 / Resumo: Observa-se que, nos últimos anos, a procura por novos processos de separação para a recuperação de ácidos orgânicos, dentre eles o ácido acrílico, a partir de seu caldo de fermentação, tem sido intensa. O processo de extração líquido-líquido apresenta-se como uma alternativa das mais viáveis para sistemas diluídos, quando se utiliza solventes apropriados e de baixa toxicidade. Na parte computacional do trabalho em questão, inicialmente, realizou-se um estudo do software Aspen Plus no que se refere à obtenção de dados termodinâmicos (parâmetros binários) e curvas binodais. Realizou-se, também, a validação do software obtendo regressões de dados experimentais envolvendo fenol e alguns solventes retirados da literatura. Algumas curvas de extração (curvas binodais), testando diferentes solventes para extração do ácido acrílico, foram construídas. As curvas binodais simuladas no Aspen também auxiliaram na escolha dos pontos experimentais, uma vez que, desta maneira, já se conhecia a região de formação de duas fases dos sistemas em estudo e pôde-se orientar a coleta destes dados laboratoriais sem o consumo excessivo de reagentes e de tempo. A parte experimental deste projeto envolve a obtenção de dados de ELL dos sistemas ternários ácido acrílico - água e os seguintes solventes: diisopropil éter, isopropil acetato, 2-etil 1-hexanol, 4- metil 2-pentanona; além do levantamento dos dados de ELL dos sistemas quaternários: ácido acrílico+água+diisopropil éter+sal, usando como sais MgCl2 e CaCl2 de concentrações de 5 e 10%, respectivamente, e ácido acrílico+água+isopropil acetato+sal, usando como sais MgCl2 e CaCl2 de concentrações de 5 e 10% respectivamente. Os resultados encontrados foram muito satisfatórios, permitindo-se construir curvas de solubilidades e realizar as regressões utilizando os modelos de coeficiente de atividade UNIQUAC e NRTL, determinando-se os parâmetros binários. Foram realizadas comparações entre os 4 solventes de extração e entre os sistemas quaternários envolvendo sais. / Abstract: It is observed that, in the last years, the search for new separation processes for recovering organic acids, such as acrylic acid produced from renewable sugar, has been intense. The liquid-liquid extraction process appears as the most viable alternative for diluted systems, since suitable solvents are used. Related to the computational part of this work, initially, a study using the software Aspen Plus for obtaining thermodynamic data (binary parameters) and binodal curves were carried out. Some extraction curves (binodal curves), testing different solvents for acrylic acid extraction, were obtained. Binodal curves simulated with Aspen Plus were very important in choosing experimental points, since, in this way, it was possible to know the region where there are immiscible two phases and, so, to facilitate the obtention of experimental data without excessive consumption of reagents and time. In the experimental section of this work, experimental data of liquid liquid equilibria (LLE) were obtained for the ternary systems acrylic acid + water + solvents (diisopropyl ether, isopropyl acetate, 2-ethyll 1-hexanol, 4 - methyl 2-pentanona), beyond obtain LLE data for the quaternary systems acrylic acid + water + diisopropyl ether + salt (using MgCl2 or CaCl2, with concentrations of 5 and 10%, respectively) and system acrylic acid + water + isopropyl acetate + salt (using MgCl2 and CaCl2 with concentrations of 5 and 10%, respectively). The results obtained were very satisfactory. Experimental solubility curves and regressed curves, using UNIQUAC and NRTL models for the activity coefficient calculations, through the binary parameters, were carried out. The results obtained with four solvents were compared and the ternary and quaternary systems (involving salts) also were compared among themselves. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientador: Maria Regina Wolf Maciel / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T22:53:00Z (GMT). No. of bitstreams: 1 Vasconcelos_ClaudiaJovitaGarcia_D.pdf: 8017563 bytes, checksum: dec61d2c1c5b8497e070bd8166b7a606 (MD5) Previous issue date: 2006 / Resumo: A otimização de processes em tempo real tem como objetivo o estudo de técnicas para a integração dos objetivos de controle aos interesses econômicos em aplicações industriais. Neste trabalho, o problema da otimização em tempo real foi abordado para um sistema complexo, com correntes de reciclo de massa e integração energética...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The goal of real-time processes optimization studies is the way to integrate control objectives and economic aspects. In this work, the real-time optimization problem was applied to a high complex system, including mass recycle streams and heat integration...Note: The complete abstract is available with the full electronic document / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

The replacement of fossil resources through renewable alternatives is one way to mitigate global climate change. Biomass is the only renewable source of carbon available for replacing oil as a refining feedstock. Therefore, it needs to be utilized not just as a fuel but for both biochemical and thermochemical conversion through biorefining. Optimizing and combining various conversion processes using a system perspective to maximize the valorization, biomass usage, and environmental benefits is of importance. This thesis work has evaluated the integration opportunities for various thermochemical conversion processes within a biorefinery system. The aim for all evaluated concepts were syngas production through gasification or reforming. Two potential residue streams from an existing biorefinery were evaluated as gasification feedstocks, thereby combining biochemical and thermochemical conversion. Torrefaction as a biomass pretreatment for gasification end-use was evaluated based on improved feedstock characteristics, process benefits, and integration aspects. A system concept, “Bio2Fuels”, was suggested and evaluated for low-temperature slow pyrolysis as a way to achieve simultaneous biomass refinement and transport driven CO2 negativity. Syngas was identified as a very suitable intermediate product for residue streams from biochemical conversion. Resulting syngas composition and quality showed hydrolysis residue as suitable gasification feedstock, providing some adjustments in the feedstock preparation. Gasification combined with torrefaction pretreatment demonstrated reduced syngas tar content. The co-gasification of biogas and wood in a FBG was successfully demonstrated with increased syngas H2/CO ratio compared to wood gasification, however high temperatures (≥1000°C) were required for efficient CH4 conversion. The demonstrated improved feedstock characteristics for torrefied biomass may facilitate gasification of biomass residue feedstocks in a biorefinery. Also, integration of a torrefaction unit on-site at the biorefinery or off-site with other industries could make use of excess low-value heat for the drying step with improved overall thermal efficiency. The Bio2Fuels concept provides a new application for slow pyrolysis. The experimental evaluation demonstrated significant hydrogen and carbon separation, and no significant volatilization of ash-forming elements (S and Cl excluded)  in low-temperature (<400°C) pyrolysis. The initial reforming test showed high syngas CH4 content, indicating the need for catalytic reforming. The collective results from the present work indicate that the application of thermochemical conversion processes into a biorefinery system, making use of by-products from biochemical conversion and biomass residues as feedstocks, has significant potential for energy integration, increased product output, and climate change mitigation.

Orientadores: Osvaldir Pereira Taranto, Flavio Vasconcelos da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T20:04:54Z (GMT). No. of bitstreams: 1 Pavanelli_PaulaEdilene_M.pdf: 1842381 bytes, checksum: ae8746d54834e8c938141f3e78903477 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta o controle e monitoramento em tempo real do regime de jorro estável através do método de identificação dos regimes de contato gás-sólido por medidas de pressão no leito de jorro. O trabalho foi realizado em duas etapas: 1) identificação em tempo real dos regimes fluidodinâmicos no processo em leito de jorro baseada na análise espectral das flutuações de queda de pressão do leito e 2) controle do processo em regime estável por malha PI. O sistema constitui-se de um leito construído em acrílico com dimensões de 0,70m de altura de coluna e 0,143m de diâmetro interno, operando com três diferentes partículas, esferas de vidro (dp = 2,59mm e Pp = 2,487 g/cm3), poliestireno (dp = 2,19mm e Pp = 1,196 g/cm3) e ABS (dp = 3,08mm e Pp = 1,029 g/cm3). Determinou-se a faixa da freqüência dominante 7,2-7,9 Hz, característico do regime de jorro estável, através do algoritmo da Transformada Rápida de Fourier (FFT) para cada partícula. Todas as medidas de pressão do leito durante o processo foram coletadas pelo sistema de aquisição através da placa PCI 6024E (National Instruments) utilizando o software LabView 7.1TM. Com o intuito de controlar o regime de jorro estável no processo em leito de jorro foram definidas como variáveis controlada e manipulada a freqüência dominante do espectro de potência (Hz) e o sinal de comando para o inversor de freqüência (V), respectivamente. A freqüência dominante foi determinada pela análise espectral das flutuações de queda de pressão no leito. O sinal de comando para inversor de freqüência atuava na variável de processo vazão de ar. Aplicaram-se perturbações degrau em malha aberta na variável manipulada para determinar os parâmetros do controlador e implementou-se a malha de controle no processo. Nos experimentos em malha fechada foram aplicadas perturbações na carga como adição de partículas e alteração na posição de abertura da válvula de ar de entrada no leito afim de testar o desempenho do controlador. Os resultados obtidos mostraram que o controlador PI manteve o sistema operando em regime estável mesmo quando aplicadas perturbações na carga, atingindo assim o objetivo do trabalho proposto / Abstract: This work describes the control and on line monitoring of the spouted bed steady regime using the gas-solid contact regimes identification method by pressure measurements. The work presents two main features: 1) the on line identification of fluid dynamic regimes in the spouted bed process based in the spectral analysis of the pressure fluctuations and 2) the process control using PI controllers. Experiments were performed in an acrylic cylindrical column 0.70m high and with 0.143m of internal diameter. The bed was made of three different particles: glass spheres (dp = 2.59mm and Pp = 2.4873 g/cm3), polystyrene (dp = 2.19mm and Pp = 1.1962 g/cm3) and ABS (dp = 3.08mm and p = 1.0286 g/cm3). The dominant frequency band was determined: 7.2-7.9 Hz for steady regime, through the algorithm of the Fast Fourier Transform (FFT), for each particle. All the measurements of pressure during the process were collected by a data acquisition system and using software LabView 7.0TM. The procedure to control the steady regime in the spouted bed process was: define the dominant frequency as the controlled variable and the signal of command for frequency inverter as the manipulated variable. The dominant frequency was determined by the spectral analysis of pressure fluctuations in the spouted bed. The command signal for frequency inverter affected the air flow variable. Step disturbances were applied in open loop in the manipulated variable to determine the parameters of the controller and control system was implemented in the process. Step disturbances like addition of particles in the spouted bed and change the position of opening of the air valve were applied in closed-loop to test the performance of the controller. The results show that PI controller was able to maintain the system operating in steady regime when disturbances were applied in the feed stream, which was the goal of this research / Mestrado / Engenharia de Processos / Mestre em Engenharia Química