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Syftet med det här examensarbetet är att undersöka möjligheter för energieffektivisering i form av ökad värmeåtervinning hos Ahlström-Munksjö Aspa Bruk AB med målet att föreslå åtgärder som minskar behovet av färskånga till uppvärmning i processerna. Detta har gjorts med hjälp av en pinchanalys där de externa behoven, pinchöverträdelser och effektiviseringsmöjligheter har identifierats och analyserats för att avgöra hur effektiv värmeväxlingen på Aspa Bruk är. Strömdata har samlats in på plats på bruket främst genom givare som loggar data kontinuerligt men även genom mätningar, miljöbesiktningsrapporter och antaganden.  Ur pinchanalysen framkom det att de externa värmebehoven potentiellt skulle kunna reduceras med ca 19,2 MW, vid ett så energieffektivt system som möjligt, jämfört med dagens behov av färskånga som ligger på 71,5 MW. I praktiken är det dock inte möjligt att genomföra åtgärder för att minska det externa värmebehovet fullständigt till följd av tekniska- och ekonomiska begränsningar. Pinchöverträdelser står för ca 7,7 MW av de ca 19,2 MW och återfinns i sekundärvärmesystemet då det råder överskott av värme i varmvatten- och hetvattenproduktionen.  De åtgärdsförslag som läggs fram bygger på att effektivisera energianvändningen och avlägsna pinchöverträdelser med åtgärder som anses genomförbara. Tre åtgärder presenteras:  Använda värmeenergin från rökgaserna från sodapannan för att förvärma förbränningsluften till sodapannan och därmed ersätta delar av färskångan som används till detta. Öka andelen flashånga från tank 2 till förbasningsfickan där flisen förvärms innan kokaren istället för terpentinkondensorn. Detta skulle medföra en reducering av färskånga till förvärmningen av flisen.  Eliminera 3 bars ångan till hetvattentanken och kompensera med ett ökat varmvattenflöde genom ett ökat intag av råvatten som ska bli varmvatten.  Totalt skulle dessa åtgärder potentiellt kunna minska förbrukningen av färskånga med ca 12,5 MW. Potentiellt skulle även mer ånga kunna sparas om rökgaserna från sodapannan tilläts kondensera. Åtgärdsförslag nummer 3 är den som bidrar mest till reduceringen av färskånga på Ahlstrom-Munksjö Aspa Bruk AB. / The purpose of this master’s thesis is to investigate opportunities for a higher energy efficiency in terms of increased heat recovery at Ahlstrom-Munksjö Aspa Bruk AB with the goal of suggesting actions that reduces the need for live steam in process heating. In order to do this a pinch analysis was conducted where the utility consumptions, pinch violations and opportunities for increased energy efficiency were identified and analyzed in order to determine how efficient the heat exchange at Aspa Bruk is. Stream data was gathered at the mill mainly through continuously logging sensor data but also through measurements, environmental inspection reports and assumptions.       From the pinch analysis it was discovered that the external hot utility potentially could be reduced by approximately 19,2 MW given that the system would be as energy efficient as possible, compared to the current need of live steam that is 71,5 MW. However, in reality it is not possible to accomplish this reduction due to technical and economic limitations. Pinch violations stand for about 7,7 MW of the 19,2 MW and are located in the secondary heat system since there is an excess of heat in the warm water- and hot water production.  The actions suggested are based on increasing the efficiency of the energy consumption and removing pinch violations and are also considered feasible. Three suggestions are presented:  Recover the heat in the fumes from the recovery boiler and use it to preheat the combustion air in to the recovery boiler and thereby replace some of the live steam used for this.  Increase the amount of flash steam from tank 2 to the preheating of the woodchips before the boiler by reducing flash steam to the turpentine condenser. This would lead to a reduction in live steam used to preheat the woodchips. Eliminate the 3-bar live steam to the hot water tank and compensate it by increasing the amount of cold water that is going to become warm water.  In total, these proposed arrangements will potentially lead to a reduction in the use of live steam of approximately 12,5 MW. Potentially even more live steam can be saved if the fumes from the recovery boiler are allowed to condense. Number 3 amongst the proposed actions is the one that has the biggest influence on the reduction of live steam at Ahlstrom-Munksjö Aspa Bruk AB.

Orientador: Roger J. Zem / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-27T02:36:46Z (GMT). No. of bitstreams: 1 Santos_LucianaCristinados_M.pdf: 3430679 bytes, checksum: 28d163db7620c9a4ecc0df34b7ae538b (MD5) Previous issue date: 2000 / Resumo: Um novo procedimento de estimativa de área e custos de capital para sistemas sob integração energética é proposto. Este método permite que restrições de troca térmica e trocadores com mais de uma passagem nos tubos sejam utilizados. O método desenvolvido resulta em um modelo não linear onde, balanços de energia, restrições de troca térmica e o fator de correção para trocadores do tipo casco e tubo 1-2 (com 1 passagem no casco e duas ou mais passagens pares nos tubos) são incluídos. As dificuldades de convergência decorrentes da adição de restrições não lineares, devido a utilização de trocadores com múltiplas passagens nos tubos, levaram ao uso de uma estratégia nova. Esta estratégia é constituída pela resolução de dois problemas não lineares. O primeiro estima a área para trocadores contracorrente constituindo a primeira aproximação para obtenção dos fatores de correção para trocadores com múltiplas passagens nos tubos, e outro onde é estimado o capital para trocadores 1-2. Os fatores de correção dos trocadores com múltiplas passagens nos tubos são calculados externamente ao modelo e entram como parâmetro conhecido. Este procedimento é repetido até que uma diferença tolerável entre as estimativas de capital seja atingida. Para completar o projeto de recuperação de energia, uma metodologia que fornece o projeto da rede de trocadores de calor considerando restrições de troca térmica é proposto. O modelo de síntese resulta na formulação de um MIP (Mixed Integer Programming), onde o problema é dividido em estágios e submetido a balanços de energia para minimizar o número de trocadores.Uma comparação dos custos de capital entre os métodos da estimativa de área e o de síntese de rede mostrou bons resultados, já que a diferença de capital entre os métodos foi inferior a 10% / Abstract: A new procedure for estimating area and capital cost targets of constrained heat exchanger networks is presented. The method allows for match constrained networks and exchangers with more than one tube passo The procedure is based on modelling the problem as a non-linear formulation where the forbidden exchanger matches are included as constraints and the temperature difference correction due to multipass exchangers is included in the modeI. The difficulty of converging to a solution due to the additional non-linear constraints imposed by the multipass exchangers required the use of a two-Ievel approach: at the inner leveI, the area targets for simple pass exchangers are obtained, and at the outer leveI the temperature difference required for multipass exchangers are computed and fed back to the inner leveI. The procedure is repeated until an appropriate tolerance between two iterations was achieved. A procedure for the authomatic synthesis of contrained heat exchanger network was developed, using a mixed integer programming approach and minimising the overall number of heat exchangers. A comparison between the estimated exchanger areas and costs estimated by the new procedure and the area and costs obtained from the final heat exchanger design shows a very good agreement / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Objetivo: O presente estudo pretendeu avaliar a força de preensão digital em trabalhadores de enfermagem a fim de determinar as médias desta força e correlacionar com os fatores pessoais e ocupacionais Métodos: Estudo descritivo, correlacional, quantitativo, realizado em um hospital de ensino de Ribeirão Preto. Os sujeitos foram categorizados por meio de um questionário que abordou características pessoais e profissionais; para a mensuração da força de preensão digital foi utilizado um dinamômetro hidráulico Preston Pinch Gauge® (North Coast Medical - Estados Unidos), por meio deste foram realizadas três mensurações consecutivas para cada medida de força e utilizou-se a média destas pinças para as análises. As coletas de dados foram realizadas em 2013, este estudo recebeu a aprovação de Comitê de Ética e Pesquisa. Compuseram a amostra 41 profissionais de enfermagem do sexo feminino, que trabalhavam no período matutino. Foram realizados testes estatísticos e o nível de significância considerado foi ? = 0, 05; o programa utilizado nas análises foi a IBM SPSS (Statistical Package for Social Science) versão 22.0. Resultados: As trabalhadoras encontravam-se na faixa etária entre 21 e 60 anos; 56,1% eram casadas e 58,5% possuíam filhos; com relação ao nível de escolaridade 43,9% tinham ensino médio completo.No que diz respeito ao vínculo empregatício atual na enfermagem, 56,1% faziam seis horas semanais e 68,3% horas extras neste vinculo; 7,3% possuíam outro vínculo na área da enfermagem, porém sem realizar horas extras. Já se afastaram do trabalho por motivo de doença 63,4%; referiram sentir dor no dedo da mão 26,8%; 95,1% das trabalhadoras realizavam atividades domésticas em sua própria casa; 70,7% não praticavam atividade física; 58,5% possuíam algum tipo de atividade de lazer, foram observadas ainda doenças osteomusculares (27,3%). Os valores da médias gerais da pinças foram: 3,64 (kgf) polpa-a-polpa,3,85 (kgf), trípode; 6,08(kgf) lateral.Conclusão: Mesmo que não se tenha identificado uma porcentagem alta em relação a carga horária de trabalho associada as horas extras e o duplo vínculo, as variáveis independentes identificadas, influenciaram o desempenho dos testes de preensão de pinça, consequentemente, na diminuição bilateral das forças de preensão das pinças digitais estudadas. Entre as categorias profissionais e as médias de pinça houve correlação positiva e significativa, destacando pinças polpa-a-polpa (mão dominante). A força de preensão digital pode ser um indicador para determinar a função da mão e poder ser usada para indicar o grau de disfunção da extremidade superior acometida, não se pode afirmar que existam alterações relacionadas aos membros superiores das trabalhadoras de enfermagem, mesmo tendo em vista que a literatura infere que muitas das patologias associadas ao membro superior têm como alguns de seus sintomas iniciais a diminuição da força de pinças, fraqueza e dor nos dedos. Seria necessário agregar aos dados avaliados de preensão de digitais mais avaliações, como as clinicas, motoras e sensitivas. Diante do incipiente número de investigações relacionadas à força de preensão digital entre estas trabalhadoras, este estudo pretendeu contribuir na prevenção do desenvolvimento de disfunções ocupacionais, com a sugestão de inserção desta avaliação nos exames médicos admissionais, periódicos, de retorno ao trabalho e demissionais / Objective: This study aimed to evaluate the digital grip strength of nursing staff in order to determine the averages of this strength and correlate it to personal and occupational factors. Methods: Descriptive, co-relational, quantitative study carried out at a teaching hospital in Ribeirão Preto. Subjects were categorised by means of a questionnaire which addressed personal and professional characteristics; for the measurement of digital grip strength the hydraulic dynamometer Preston Pinch Gauge® (North Coast Medical - the United States) was used, with which three consecutive readings were made for each strength measurement and the mean of the pinches was used for the analysis. Data collection was performed in 2013 and this study was approved by the Research and Ethics Committee. 41 female nursing staff members composed the samples, all of whom worked in the morning. Statistical tests were made and the significance level considered was ? = 0.05; the program used for the analysis was IBM SPSS (Statistical Package for Social Science) version 22.0. Results: The workers were aged between 21 and 60 years; 56.1% were married and 58.5% had children; regarding the level of education 43.9% were high- school graduates. Concerning the current nursing employment relationship 56.1% worked six hours per week and 68.3% overtime in such relationship; 7.3% had other nursing labour bonds although not working overtime. 63.4% were away from work due to health complications; 26.8% indicated to suffer from finger pain; 95.1% of the workers performed household chores in their own houses; 70.7% did not do any physical activity; 58.5% had some kind of leisure activity, and osteomuscular conditions were still observed (27.3%). General mean values found were: 3.64 (kgf) pulp to pulp, 3.85 (kgf) three points and 6.08 (kgf) lateral pinch. Conclusion: Although there was not an identification of a higher percentage related to the working hours associated to overtime and double labour bond, the independent variables identified affected the pinch grip test performance, consequently reducing bilaterally the digital pinch grip strengths analysed. There was positive and significant correlation between the professional categories and the pinch means, highlighting pulp to pulp pinch(dominant hand). Digital grip strength can be an indicator to determine hand function and can be used to demonstrate the level of dysfunction of the affected upper limb ends, but it cannot be stated that there are alterations related to the upper limbs of nursing staff, even considering that the literature infers that many pathologies associated to the upper limbs present the reduction of pinch strength and finger weakness and pain as some of their initial symptoms. It would be necessary to add more evaluations to the already analysed data on digital grip, such as clinical, motor and sensitive evaluations. Before the incipient number of investigations related to the digital grip force among these workers, this study intended to contribute to the prevention of the development of occupational dysfunctions, suggesting the further introduction of this evaluation to admission, periodic, return to work and discharge medical examinations

Orientador: Antonio Carlos Bannwart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-25T04:21:28Z (GMT). No. of bitstreams: 1 Higa_Marcio_M.pdf: 7914219 bytes, checksum: c0df34dbad62f75065ad547646e7c5c8 (MD5) Previous issue date: 1999 / Resumo: Através dos métodos do "pinch-point" e da programação linear, foram realizadas diversas simulações e análises térmicas de uma planta típica de produção de açúcar e álcool, visando a máxima recuperação de calor e a redução do consumo de vapor. As simulações foram divididas em três grupos. No primeiro, usou-se o método do "pinch-point" para investigar basicamente a planta de produção de açúcar, analisando também a influência de diversas alternativas (eliminação de sangrias de vapor entre estágios de evaporação, número de efeitos de evaporação, compressão mecânica do vapor do último estágio de evaporação, área e número de trocadores de calor). No segundo grupo, na mesma planta, empregou-se o método de programação linear, a fIm de determinar a distribuição otimizada das sangrias de vapor para pré-aquecimento do caldo. No terceiro grupo de análises, considerando também o consumo na produção de álcool, retomou-se ao método do "pinch-point", onde as sangrias foram primeiramente maxirnizadas nos últimos estágios de evaporação e em seguida ajustadas para satisfazer as áreas dos evaporadores existentes na planta básica. Para tanto, foi desenvolvido um programa de computador específico que permite a simulação do efeito das diversas variáveis, inclusive a razão de produção açúcar/álcool. Diversas alternativas de grande impacto no consumo de vapor são apresentadas / Abstract: Using pinch technology and linear prograrnrning, several simulations of thermal analysis of a typical sugar cane plant and alcohol production were performed. The objective was the maximum heat recovery and the reduction of steam consumption. The simulations were divided into three groups. In the fIrst, pinch technology was applied to analyze only the sugar cane basic plant production and the influence of several alte~natives (elimination of vapor bleed between evaporator effects, number of evaporator effects, mechanical compression of vapor in the last effect of evaporation, area and number of heat exchangers). In the second group, use was made of linear prograrnrningin the same plant to determine the optimized confIguration of vapor bleeds for juice preheating. In the third group, pinch technology was again applied, including the consumption from alcohol production. First of ali, the maximum vapor bleed was assumed at the last effects of evaporation, then adjusted to adapt to the evaporator areas of basic plant. Therefore, a specifIc computer programming was developed to simulate the several variable, including the ratio of production sugar/alcohoL Several alternatives of deep impact in steam consumption were investigated. / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

The purpose of this project is to find an identification tag that can be used in a future automated pinch analysis tool. It can be used to further analyse composite curves and pinch results by tracking the original streams that was converted. In real life situations, retrofitting a process industries streams, can decrease heat demands and costs. A pinch analysis and a heat exchange network is created with fixed and flexible flows to show a recommendation on how the system model can handle this type of situations. The models have been created by hand with support from pinch literature and the calculations validated with mathematical software such as matlab and other graphing tools. The literature study and pinch modelling resulted in a recommendation of tagging Hstart and Hend for each individual stream. By using a geographical tag in a coordinate system the analyst will be able to find the original streams in the pinch analysis and composite curves. The project also resulted in a heating exchange network created from the fixed and flexible data set. The enthalpy differences between the ideal pinch result and the fixed data set is smaller than one might expect because of enthalpy abundance in the specific intervals.

A wide range of unstable current driven MHD modes is present in the re- versed τeld pinch (RFP) conτguration. An ideally conducting wall facing the plasma can stabilize the ideal MHD modes. In the presence of a resistive wall characterized by the wall time τw, fast mode rotation with the frequency exceeding the inverse wall time gives stabilization for resistive MHD modes. The ideal MHD modes in the RFP are non-rotating modes and can not be stabilized by the resistive wall. Instead they are converted into resistive wall modes (RWM) growing with a growth rate proportional to the inverse of the wall time τw. EXTRAP T2R is an RFP device equipped with a thin resistive wall having the wall time shorter than the plasma pulse duration τw < τp. This feature allows the study of non-resonant non-rotating resistive wall modes. Resistive wall modes dynamics has been studied in EXTRAP T2R . RWM growth rates has been measured and compared with linear MHD stability calculations. Quantitative agreement is observed. In the case τw < τp the RWM can cause discharge degradation and should be stabilized. Active feedback is the way to stabilize the RWM in the RFP. An intelligent shell scheme is one possible feedback scenario. An active feed- back system including a set of sensors and discrete active coils is installed in EXTRAP T2R. The intelligent shell tries to keep the magnetic flux zero at the positions of the sensor. The analog PID controller for the intelligent shell feedback scheme has been studied. A model of the active control system was developed and comparison with the experimental results showed good agree- ment. Encouraging experimental results on the active feedback stabilization of multiple RWMs in the RFP plasmas were obtained.

Scope and contents: The static and dynamic electrical characteristics of silicon n-channel MOS FETs are studied down to cryogenic temperatures. Particular emphasis is directed towards the effect of interface states on the temperature dependence of both the pinch-off voltage and 1/f noise. / No abstract included. / Thesis / Master of Engineering (MEngr)

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Ph. D. Thesis / In order to compute more realistic production plans and schedules, techniques using nonlinear programming (NLP) and mixed-integer nonlinear programming (MINLP) have gathered a lot of attention from the industry and academy. Efficient solution of these problems to a proven ε-global optimality remains a challenge due to their combinatorial, nonconvex, and large dimensionality attributes. The key contributions of this work are: 1) the generalization of the inventory pinch decomposition method to scheduling problems, and 2) the development of a deterministic global optimization method. An inventory pinch is a point at which the cumulative total demand touches its corresponding concave envelope. The inventory pinch points delineate time intervals where a single fixed set of operating conditions is most likely to be feasible and close to the optimum. The inventory pinch method decomposes the original problem in three different levels. The first one deals with the nonlinearities, while subsequent levels involve only linear terms by fixing part of the solution from previous levels. In this heuristic method, infeasibilities (detected via positive value of slack variables) are eliminated by adding at the first level new period boundaries at the point in time where infeasibilities are detected. The global optimization algorithm presented in this work utilizes both piecewise McCormick (PMCR) and Normalized Multiparametric Disaggregation (NMDT), and employs a dynamic partitioning strategy to refine the estimates of the global optimum. Another key element is the parallelized bound tightening procedure. Case studies include gasoline blend planning and scheduling, and refinery planning. Both inventory pinch method and the global optimization algorithm show promising results and their performance is either better or on par with other published techniques and commercial solvers, as exhibited in a number of test cases solved during the course of this work. / Thesis / Doctor of Philosophy (PhD) / Optimal planning and scheduling of production systems are two very important tasks in industrial practice. Their objective is to ensure optimal utilization of raw materials and equipment to reduce production costs. In order to compute realistic production plans and schedules, it is often necessary to replace simplified linear models with nonlinear ones including discrete decisions (e.g., “yes/no”, “on/off”). To compute a global optimal solution for this type of problems in reasonable time is a challenge due to their intrinsic nonlinear and combinatorial nature. The main goal of this thesis is the development of efficient algorithms to solve large-scale planning and scheduling problems. The key contributions of this work are the development of: i) a heuristic technique to compute near-optimal solutions rapidly, and ii) a deterministic global optimization algorithm. Both approaches showed results and performances better or equal to those obtained by commercial software and previously published methods.