Made available in DSpace on 2014-10-09T12:25:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:38Z (GMT). No. of bitstreams: 1 06172.pdf: 5264843 bytes, checksum: a22f14e596334a88838be0798f8a00e9 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

The purpose of this research was to design, fabricate and test a 1 liter per minute pilot plant with a cascading sequence of continuously stirred tank reactors. The object of the research was to chemically decolorize selected reactive-dye bath concentrates resulting from exhaustive dyeing, and to remove metals and DOC using Fenton's Reagent or the reductive chemicals, thiourea dioxide and sodium hydrosulfite. For the Fenton's Reagent studies, ferrous sulfate was premixed with the dye waste concentrate before overflowing to the first reactor. A feedback control system based on color remaining in the discharge was used to regulate reactants added. Transmittance was measured at several wavelengths (590, 540, and 438 nm) and the American Dye Manufacturers Institute (ADMI) value calculated. The results demonstrated that ADMI measurements could not be made on dark solutions (over 3000 ADMI) in the pilot plant and, typically, one wavelength was used for control. DOC removal was used as a means of determining the biological activity in aerated reactors following color removal. The initial pilot plant studies were conducted using Navy 106 jet-dye waste. Reductive pretreatment with thiourea dioxide resulted in 92.2% color removal with color returning upon aeration for an overall color removal of 76.6%. Oxidative pretreatment with Fenton's chemistry resulted in 98.8% color removal with overall color removal after aerobic treatment at 96.8%. Dissolved Organic Carbon (DOC) removal in aerobic treatment improved with oxidative pretreatment relative to reductive pretreatment on Navy 106 jet-dye concentrate. On site operation of the pilot plant on other dye wastes showed color removals above 95% and DOC removals of 38% and 19% for an azo-based red dye waste concentrate and a copper-phthalocyanine-based dye, Ming Jade, respectively. The soluble copper concentration in the Ming Jade was decreased from 19.2 ppm to 4.5 ppm. This corresponded to a 3-fold increase in suspended solids from 0.575 g/L to 1.505 g/L. The results showed that continuous oxidative pretreatment with a 15-minute residence time was controllable and more effective than reductive treatment for color removal. Oxidative pretreatment also decreased the soluble copper concentration in a copper containing waste water, and did not hinder biological activity. / Master of Science

Man has long been hampered in his efforts to grow food plants, raise animals, and carry on other activities of an advancing civilization by obnoxious plants or weeds. Weeds add greatly to man’s labors and resist his efforts of control because they can often survive frost, high temperatures and drought, can grow under widely varying soil and climatic conditions, and produce enormous amounts of seeds that will survive for years. The control of weeds is rapidly becoming of increasing importance throughout all agricultural areas and is playing a part in the broad conservation program. Tillage operations are both time consuming and expensive, often representing from one tenth to one third of the total value of the crops produced. Weeds compete with crops for water, nutrients, and light; they help spread diseases; some are poisonous to animals; some disrupt water distribution and flow along waterways and spread their seeds to irrigated land; and they are hazardous and bothersome to train movements when growth covers the rails. The methods of weed control are many and varied. Among the most common methods of weed control are hand, mechanical, biological, burning and chemical methods. It has been said that even if the cost of application of chemicals is as high as 15 to 20 dollars per acre, it is cheaper than the older hand or mechanical methods. There is no one chemical that will give control of all weeds without undue hazards, and therefore, the use of selective weed killers has become essential. Annual and perennial grasses, such as quack, johnson, and bermuda, are among the most obnoxious of the weeds. Sodium trichloroacetate, arsenical compounds, and chlorates are the only commercial weed killers that will control noxious grasses; since the arsenicals are poisonous and chlorates flammable, sodium trichloroacetate is expected to supplement them in grass control. The demand for this compound is expected to exceed the supply for the next few years. It is the purpose of this investigation to design, construct, and operate a pilot plant for this production of sodium trichloroacetate from acetic acid and chlorine, and further, to study the compounding of chloral hydrate and sodium chlorate to give desirable grass killer formulation. / Master of Science

Submitted in fulfillment of the requirements for the degree of Doctor of Technology in Business Administration, Entrepreneurial Studies & Management Department, Durban University of Technology, Durban, South Africa, 2015.

nÃo hà / Na primeira parte deste trabalho, empregamos uma rede neural artificial (RNA) treinada com algoritmo back-propagation para inferir a volatilidade dos gases liquefeitos de petrÃleo (GLP) produzidos em uma torre de fracionamento de lÃquido de gÃs natural (LGN). Os resultados obtidos indicam que a RNA fornece melhores respostas do que um simulador desenvolvido com base fenomenolÃgica que se encontra em fase de implementaÃÃo na planta em estudo. Na segunda parte da dissertaÃÃo, o nosso objetivo primordial à demonstrar que os fluxogramas de processos de refinarias de petrÃleo podem estar intrinsecamente associados à topologias de redes complexas, que sÃo scale-free, exibem efeitos de mundo pequeno e possuem organizaÃÃo hierÃrquica. A emergÃncia dessas propriedades em redes artificiais à explicada como uma consequÃncia dos princÃpios usados no design de projeto dos processos, os quais incluem regras heurÃsticas e tÃcnicas algorÃtmicas. Esperamos que esses resultados sejam tambÃm vÃlidos para plantas quÃmicas de diferentes tipos e capacidades. / In the first part of this work we apply an artificial neural network (ANN) trained with a back-propagation algorithm to predict the volatility of liquefied petroleum gases (LPG) produced from a fractionation tower of natural gas liquid (NGL). Our analysis indicate that the ANN scheme provides better results than a simulator developed based phenomenological which is currently being implemented in the plant under study. In the second part, our primary objective is to demonstrate that flowsheets of oil refineries can be intrinsically associated to complex network topologies, which are scale-free, display small-word effect and have hierarchical organization. The emergence of these properties artificial networks is explained as a consequence of the design principles used in the processâ design, which include heuristics rules and algorithmic techniques. We expect these results to be also valid for chemical plants of different types and capacities.

La contribución que se pretende con esta tesis se refiere a la implantación de un sistema de diagnosis de fallos en plantas químicas completas integrado al sistema de supervisión, gestión y control de la producción.El sistema de diagnosis de fallos que se presenta consiste en una combinación de un sistema de reconocimiento de patrones basado en redes neuronales artificiales y un sistema de inferencia basado en la lógica difusa. La información necesaria para desarrollar el sistema de diagnosis incluye los datos históricos, un análisis de riesgo y operabilidad y un modelo de la planta química. La entrada al sistema son las mediciones directas o indirectas de la planta y la salida consiste en una señal para cada fallo (0: no fallo; 1: fallo). Primero se definen los fallos posibles. La red neuronal se entrena con datos históricos de fallos ocurridos en el pasado, con el objeto de reconocer los patrones respectivos. En el caso de que no se posean los datos históricos de alguno de los fallos, por ejemplo porque nunca hayan ocurrido, se obtienen los patrones mediante la simulación, usando el modelo de la planta. El sistema de lógica difusa contiene un conjunto de reglas si-entonces que pueden ser de dos tipos: las basadas en el conocimiento de la planta, mediante el análisis de riesgo o la experiencia con la simulación, y las basadas en la experiencia con el uso de la red neuronal, previamente entrenada. Otro aspecto novedoso es la posibilidad de entrenar la red neuronal con "características" extraídas de las variables medidas mediante su pre-procesamiento con wavelets. Esta variante permite obtener un alto rendimiento del sistema de diagnosis en plantas químicas discontinuas y continuas complejas. Para optimizar los parámetros de los componentes del sistema de diagnosis se propone un índice de rendimiento. Además, se utiliza el índice de rendimiento para comparar el sistema propuesto con otros métodos.Las señales dadas por el sistema de diagnosis pueden ser usadas por el sistema de programación de la producción para actualizar el plan de la manera más efectiva, por el sistema de control para actuar en forma automática y por los operadores de planta como soporte para la toma de decisiones. Se han sentado las bases para la traducción de la salida del sistema de diagnosis para su utilización por los demás niveles del soporte informático. Se usa una estrategia basada en el análisis de riesgo y operabilidad de la planta.El sistema propuesto es consecuencia de sucesivas mejoras, al trabajar con diferentes casos de estudio. Los escenarios académicos corresponden a una planta química continua con una corriente de reciclo y un reactor discontinuo. Los casos a escala de planta piloto corresponden a escenarios construidos en la UPC: un reactor de gasificación, un reactor semicontinuo y una planta discontinua multipropósito. Los escenarios industriales corresponden a dos refinerías de azúcar y a un sector de una planta petroquímica.El sistema propuesto muestra ser ventajoso respecto a otros métodos tanto en cuanto a la rapidez de diagnosis como en cuanto a su capacidad para aislar los fallos. La simplicidad del desarrollo y la flexible estrategia de implementación del sistema propuesto auguran un futuro promisorio a la tecnología presentada. Nuevas líneas de investigación se pueden emprender mediante el desarrollo de un sistema de gestión de las alarmas. Otro aspecto importante es la posibilidad de participar en la estandarización de las interfaces del programa de diagnosis. / The pretended contribution of this thesis deals with the implementation of a fault diagnosis system in chemical plants integrated to the monitoring, management and control system. The proposed fault diagnosis system consists in a combination of a pattern recognition approach based on artificial neural networks and an inference system based on fuzzy logic. The information needed to develop the fault diagnosis system includes the historical data, the hazard and operability study and the model of the chemical plant. The inputs to the system are the direct or indirect measurements from the plant and the output consists in a signal for each fault (0: no fault; 1: fault). First, the possible faults are defined. The artificial neural network is trained with historical data of faults occurred in the past, with the aim of recognising the respective patterns. In the case that the corresponding historical data are not available, for example due to the no occurrence of the fault, the patterns are obtained through simulation, using the plant model. The fuzzy logic system contains a set of if-then rules that can be of two types: those based in the process knowledge, by the hazard analysis or by the experience with simulation, and those based on the experience with the use of an artificial neural network, previously trained. Other novel aspect is the possibility of artificial neural network training by using signals features that are extracted by its pre-processing using wavelets. This alternative allows a higher fault diagnosis system performance in batch and complex continuous chemical plants. In order to optimise the parameters of the components of the fault diagnosis system, a performance index is proposed. The performance index is also utilised to compare the proposed fault diagnosis system against other methods.The signals provided by the fault diagnosis system can be used by the scheduling system to update the schedule in the most effective way, by the control system to take automated control actions and by plant's operators as support for decision-making. The basis of the translation of the system output, for its utilisation at other levels in the information system, has been settled.The proposed strategy is based on the hazard and operability analysis.The proposed system is the result of successive improvements, by working with different case studies. The academic scenarios correspond to a continuous chemical plant with a recycle stream and a batch reactor. The pilot plant scale cases correspond to scenarios built at UPC: a reactor gasifier, a fed-batch reactor and a multipurpose batch chemical plant. The industrial scenarios correspond to two sugar refineries and a sector of a petrochemical plant.The proposed system shows to be advantageous with respect to other methods in relation to the fastness of the diagnosis and also its capacity to isolate faults. The simplicity of the development and the flexible strategy of implementation of the proposed fault diagnosis system give a promising future to the presented technology. New research lines can be considered by developing the alarm handling system. Other important aspect is the possibility of the participation in the standardisation of the interfaces of the fault diagnosis program.

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.

M.Phil. / In modern society, professional engineers, technologists and technical managers are responsible for the planning, design, manufacture, maintenance and operation of the processes and systems ranging from simple processes to complex systems. The failure of these can often cause effects that range from inconvenience and irritation to severe impact on the society and its environment. Users, customers and society in general expect that products be reliable and safe at all times (Allan & Ballinton 1992). The biggest investment in any plant is, arguably, on individual plant equipment. It is therefore reasonable to give the greatest attention possible to the health and integrity of equipment that form part of the chemical process plant.Most of plant failures occur without warning and this result in equipment breakdowns, huge production losses and expensive maintenance. The reaction to plant failures has, in most cases, been a reactive maintenance which means that the plant equipment must fail before the cause of fault is investigated and the equipment is repaired. Reactive maintenance has shortcomings in that it is successful in solving problems temporarily but does not guarantee prevention of fault recurrence. Equipment and process failures waste money on unreliability problems. The question that arises is. ‘How reliable and safe is the plant during its operating life?’ This question can be answered, in part, by the use of quantitative reliability evaluation. The growing need to achieve high availability for large integrated chemical process systems demands higher levels of reliability at the operational stage. Reliability is the probability of equipment or processes to function without failure when operated correctly for a given interval of time under stated conditions. This research dissertation is aimed at developing equipment optimisation program for the chemical process plant by introducing a logical approach to managing the maintenance of plant equipment. Some relevant reliability theory is discussed and applied to the Short – Path Distillation (SPD) plant of SASOL WAX. An analysis of the failure modes and criticality helps to identify plant equipment that needs special focus during inspection.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-10-10T18:36:07Z No. of bitstreams: 1 TeseAOC.pdf: 3133234 bytes, checksum: fa3788cc1616002b40bb53fd23954c58 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T12:01:29Z (GMT) No. of bitstreams: 1 TeseAOC.pdf: 3133234 bytes, checksum: fa3788cc1616002b40bb53fd23954c58 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T12:01:36Z (GMT) No. of bitstreams: 1 TeseAOC.pdf: 3133234 bytes, checksum: fa3788cc1616002b40bb53fd23954c58 (MD5) / Made available in DSpace on 2016-10-21T12:01:42Z (GMT). No. of bitstreams: 1 TeseAOC.pdf: 3133234 bytes, checksum: fa3788cc1616002b40bb53fd23954c58 (MD5) Previous issue date: 2016-07-08 / Não recebi financiamento / Chemical plants are increasingly complex and integrated with recycle streams promoting energy integration and increasing process yield. This results in a complex dynamic behavior which can interfer in control systems design. Decentralized control systems are an alternative although this methodologie is not always e ective once that interactions between process units are not considered. In this work, decentralized coordinated optimization with severous methods of coordination is applied to a reactor- ash systems and Williams-Otto plant, getting satisfatory results for these chemical plants. Then, we develop a control system to complex chemical plants that are decomposed in subsystems, combine decentralized coordinated optimization with strategies of plantwide control theory to ensure that processes operate in conditions comply with global and local demands, minimizing the e ect of disturbances in the system and avoiding snowball e ect, characteristics of this type of systems since both methodologies consider the interconnections of the systems. The methodology is applied to design of control systems to Williams-Otto plant, because of complexity of its optimization problem and high f interaction between its process units. The result is a control systems of complex chemical plants with high performance and e ciency, with smooth actions in face of fast disturbances and minimizing their e ects along the plants. Futhermore, there is the importance of applying plantwide control theory in the proposed system, even if decentralized coordinate optimization is used that, alone, does not guarantee the performance and e ectiveness of the designed system. / As plantas químicas industriais estão cada vez mais complexas e integradas, com a presença de correntes de reciclo promovendo a integração energética e o aumento do rendimento do processo. Isto resulta em um comportamento dinâmico complexo, que pode dificultar o projeto de um sistema de controle eficaz para a planta. Sistemas de controle descentralizado são uma alternativa. Porém, esta metodologia nem sempre é eficaz uma vez que as interações entre as unidades de processamento da planta não são consideradas. Neste trabalho, a otimização descentralizada coordenada a partir de diferentes métodos de coordenação é testada para um sistema composto de um reator e um vaso flash e para a planta de Williams-Otto, obtendo resultados satisfatórios para as plantas químicas selecionadas. Posteriormente, desenvolveu-se uma estrutura de controle para Plantas químicas complexas que são decompostas em subsistemas, aliando a otimização descentralizada coordenada com estratégias de controle plantwide, de modo a garantir que o processo opere em condições que atendam as demandas globais e locais, minimizando o efeito das perturbações no sistema e evitando o “efeito bola de neve", característico deste tipo de sistema, uma vez que ambas metodologias consideram as interconexões do sistema que compõem a planta química. A metodologia é aplicada a planta de Williams-Otto em virtude da complexidade de seu problema de otimização e a alta influência das interações entre as unidades de processamento para o comportamento do sistema. Isto resulta em um sistema de controle de plantas químicas complexas com alto desempenho e eficiente, com respostas suaves às perturbações rápidas e minimização da propagação dos efeitos destas na planta. Além disto, verifica-se a importância de se aplicar heurísticas de controle plantwide na eficacia do sistema proposto, mesmo que este utilize a otimização descentralizada coordenada que, de maneira isolada, não garante o desempenho do sistema projetado.

Hot water discharges and potential chemical spills are factors that threaten water quality in cooling reservoirs of chemical and power plants. In this thesis, three models are used to analyze the impact of these factors in a particular case study.