Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Includes bibliographical references. / M.S.

Thesis (Ph. D.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--University of North Texas, May, 2008. / Title from title page display. Includes bibliographical references.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: Ref 1-Ref 7. / by Walter Herbert Strohmayer. / Ph.D.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2006. / A small scale steam jet ejector experimental setup was designed and manufactured. This ejector setup is of an open loop configuration and the boiler can operate in the temperature range of Tb = 85 °C to 140 °C. The typical evaporator liquid temperatures range from Te = 5 °C t o 10 °C while the typical water cooled condenser presure ranges from Pc = 1 . 70 kPa t o 5. 63 kPa (Tc = 15 °C to 35 °C). The boiler is powered by by two 4kW electric elements, while a 3kW electric element simulates the cooling load in the evaporator. The electric elements are controlled by means of variacs. The function ... / Centre for Renewable and Sustainable Energy Studies

The presence of deposits on the secondary side of pressurized water reactor (PWR) steam generator systems is one of the main contributors to the high maintenance costs of these generators. Formation and transport of corrosion products formed due to the presence of impurities, metals and metallic oxides in the secondary side of the steam generator units result in formation of deposits. This research deals with understanding the deposit formation and characterization of deposits by studying the samples collected from different units in secondary side system at Comanche Peak Steam Electric Station (CPSES). Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have been used for studying the phases, morphologies and compositions of the iron oxides formed at Unit 1 and Unit 2 of secondary side of steamgenerator systems. Hematite and magnetite were found to be the dominant phases of iron oxides present in the units. Fe, Cr, O, Ni, Si, Cl and Cu were found in samples collected from both the units. A qualitative method was developed to differentiate iron oxides using laser induced breakdown spectroscopy (LIBS) based on temporal response of iron oxides to a high power laser beam. A quantitative FTIR technique was developed to identify and quantify iron oxides present in the different components of the secondary side of the steam generator of CPSES. Amines are used in water treatment to control corrosion and fouling in pressurized water reactors. CPSES presently uses an amine combination of dimethylamine (DMA), hydrazine and morpholine to control the water chemistry. Along with the abovementioned amines, this study also focuses on corrosion inhibition mechanismsof a new amine DBU (1, 8-diazabicyclo [5.4.0] undec-7-ene). Electrochemical impedance spectroscopy and polarization curves were used to study the interaction mechanism between DBU solution and inconel alloys 600 and 690 at steamgenerator operating temperatures and pressures. Of all the amines used in this study (DMA, DBU, ETA, and morpholine), DMA was more effective at keeping the passive film formed on the alloy 600 surface from failing at both ambient and high temperatures. Morpholine was found result in higher corrosion resistance compared to the other amines in case of alloy 690.

Este trabalho propõe desenvolver um projeto de controle de um sistema de geração de vapor composto por múltiplas caldeiras que contemple a otimização do consumo de combustível do sistema. Para atingir este objetivo, deve-se combinar um controle regulatório eficiente de uma caldeira e um mecanismo divisor de carga eficiente para que cada caldeira opere com a confiabilidade normalmente requerida, aliado a um ponto ótimo de consumo de combustível. Esta dissertação apresenta: a modelagem dinâmica de uma caldeira aquatubular industrial; a implementação computacional do modelo dinâmico de uma caldeira aquatubular em Matlab; o projeto de controle de uma caldeira aquatubular no sistema de automação 800xA envolvendo a definição de estratégias de controle, a comunicação do sistema de automação com o modelo da planta no Matlab, uma avaliação sobre algumas técnicas de sintonia, bem como a sua simulação dinâmica e resultados; o problema de otimização para minimização do consumo de total de combustível de um sistema de geração de vapor com múltiplas caldeiras, bem como a avaliação de sua resolução com modelagem por uma abordagem de Programação Linear Inteira Mista; e o projeto de controle de um sistema com múltiplas caldeiras, envolvendo também a simulação dinâmica. Com base nos experimentos simulados considerou-se que a estratégia de controle proposta neste trabalho tem desempenho satisfatório, principalmente pelo fato de que a inclusão do bloco divisor de carga não acarretou prejuízo na característica de rejeição de perturbações, o que encoraja estudos posteriores com o objetivo de se ter uma utilização prática. / This study proposes to develop a control project for a multiple boilers steam generation system that includes fuel optimization. To achieve that, it must combine an efficient boiler regulatory control and an efficient mechanism for load allocation to each boiler in order to operate with normally required reliability and combined with optimum fuel consumption. This dissertation presents: dynamic modeling of an industrial watertube boiler; computational implementation of the dynamic watertube Boiler model in Matlab, the control design of a watertube Boiler in 800xA automation system involving the definition of control strategies, communication of the 800xA automation system with the plant model in Matlab, an evaluation of some techniques for PID tuning including dynamic simulation results, the optimization problem to minimize the total fuel consumption of a multiple boilers steam generation system, as well as the assessment of their resolution with Mixed Integer Linear Programming modeling approach, and control design of a multiple boilers system, also involving dynamic simulation. Based on simulated experiments it was found that the control strategy proposed in this work has satisfactory performance, mainly because of the inclusion of the divider block load did not affect the rejection of disturbances characteristic, which encourages further studies with objective of practical use.

Este trabalho propõe desenvolver um projeto de controle de um sistema de geração de vapor composto por múltiplas caldeiras que contemple a otimização do consumo de combustível do sistema. Para atingir este objetivo, deve-se combinar um controle regulatório eficiente de uma caldeira e um mecanismo divisor de carga eficiente para que cada caldeira opere com a confiabilidade normalmente requerida, aliado a um ponto ótimo de consumo de combustível. Esta dissertação apresenta: a modelagem dinâmica de uma caldeira aquatubular industrial; a implementação computacional do modelo dinâmico de uma caldeira aquatubular em Matlab; o projeto de controle de uma caldeira aquatubular no sistema de automação 800xA envolvendo a definição de estratégias de controle, a comunicação do sistema de automação com o modelo da planta no Matlab, uma avaliação sobre algumas técnicas de sintonia, bem como a sua simulação dinâmica e resultados; o problema de otimização para minimização do consumo de total de combustível de um sistema de geração de vapor com múltiplas caldeiras, bem como a avaliação de sua resolução com modelagem por uma abordagem de Programação Linear Inteira Mista; e o projeto de controle de um sistema com múltiplas caldeiras, envolvendo também a simulação dinâmica. Com base nos experimentos simulados considerou-se que a estratégia de controle proposta neste trabalho tem desempenho satisfatório, principalmente pelo fato de que a inclusão do bloco divisor de carga não acarretou prejuízo na característica de rejeição de perturbações, o que encoraja estudos posteriores com o objetivo de se ter uma utilização prática. / This study proposes to develop a control project for a multiple boilers steam generation system that includes fuel optimization. To achieve that, it must combine an efficient boiler regulatory control and an efficient mechanism for load allocation to each boiler in order to operate with normally required reliability and combined with optimum fuel consumption. This dissertation presents: dynamic modeling of an industrial watertube boiler; computational implementation of the dynamic watertube Boiler model in Matlab, the control design of a watertube Boiler in 800xA automation system involving the definition of control strategies, communication of the 800xA automation system with the plant model in Matlab, an evaluation of some techniques for PID tuning including dynamic simulation results, the optimization problem to minimize the total fuel consumption of a multiple boilers steam generation system, as well as the assessment of their resolution with Mixed Integer Linear Programming modeling approach, and control design of a multiple boilers system, also involving dynamic simulation. Based on simulated experiments it was found that the control strategy proposed in this work has satisfactory performance, mainly because of the inclusion of the divider block load did not affect the rejection of disturbances characteristic, which encourages further studies with objective of practical use.

The presence of deposits leading to corrosion of the steam generator (SG) systems is a major contributor to operation and maintenance cost of pressurized water reactor (PWR) plants. Formation and transport of corrosion products formed due to the presence of impurities, metallic oxides and cations in the secondary side of the SG units result in formation of deposits. This research deals with the characterization of deposit samples collected from the two SG units (unit 1 and unit 2) at Comanche Peak Steam Electric Station (CPSES). X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques have been used for studying the compositional and structural properties of iron oxides formed in the secondary side of unit 1 and unit 2. Magnetite (Fe3O4) was found to be predominant in samples from unit 1 and maghemite (g-Fe2O3) was found to be the dominant phase in case of unit 2. An attempt has been made to customize FTIR technique for analyzing different iron oxide phases present in the deposits of PWR-SG systems.

Flow accelerated corrosion (FAC) is a major concern in the power industry as it causes thinning of the pipes by the dissolution of the passive oxide layer formed on the pipe surface. Present research deals with comparing the protection offered by the magnetite (Fe3O4) versus maghemite (γ-Fe2O3) phases thickness loss measurements. Fourier transform infrared spectroscopy (FTIR) is used in distinguishing these two elusive phases of iron oxides. Representative pipes are collected from high pressure steam extraction line of the secondary cycle of unit 2 of Comanche Peak Steam Electric Station (CPSES). Environmental scanning electron microscopy (ESEM) is used for morphological analysis. FTIR and X-ray diffraction (XRD) are used for phase analysis. Morphological analysis showed the presence of porous oxide surfaces with octahedral crystals, scallops and "chimney" like vents. FTIR revealed the predominance of maghemite at the most of the pipe sections. Results of thickness measurements indicate severe thickness loss at the bend areas (extrados) of the pipes.