146 research outputs found

    Unsolved accidents in fuel storage tanks : Resolution methodology by mathematical modeling under systemic appproach.

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    Storage of mixtures of heavy hydrocarbon fuels with lighter components is a worldwide necessity because of their use for the construction of roads (asphalt diluted), the energy for industrial production (furnaces, boilers, electrical generators) and power for international transportation by ship of huge amounts of goods (big size internal combustion engines). This allows the development of a number of activities, provides the support for the production of goods and services worldwide, although its contribution appears invisible to the life as we know and for the world surrounding us as we perceive it. For its use, the heavy hydrocarbon fuels need to be handled, stored, transported, and transferred. All this operations have high risk of explosion. This thesis focuses on the explosions inside heavy fuel storage tanks. Particularly those that occurred long ago and have not had a full explanation. In this Thesis a generic methodology for determining hazardous atmospheres inside fuel tanks has been set, the modeling the combustion process inside the tank from the ignition in the presence of a spark or flame in the vicinity of an opening of the tank, and the consequences of this combustion ( resulting in a possible explosion ) on persons in the vicinity of the tank. This job was done in the expectative of be making a contribution to the investigation of such kind of unsolved accidents.Las mezclas basadas en hidrocarburos pesados con componentes más livianos se utilizan en la construcción de carreteras (diluido asfáltico), en la energía para la producción industrial (hornos, calderas, generadores eléctricos) y en la generación de potencia de accionamiento para el transporte internacional por barco de enormes cantidades de bienes (motores de combustión interna de gran porte). Esto permite el desarrollo de una serie de actividades, ofrece el apoyo a la producción de bienes y servicios a nivel mundial, aunque su contribución aparece invisible para el mundo que nos rodea tal como lo percibimos. Para su uso, los combustibles de hidrocarburos pesados se manipulan, almacenan, transportan y transfieren. Todas estas operaciones tienen un alto riesgo de explosión. Esta tesis se centra en las explosiones dentro de los tanques de almacenamiento de combustible pesado. Particularmente los que ocurrieron hace mucho tiempo y no han tenido una explicación completa. En la misma se ha establecido una metodología genérica para la determinación de las atmósferas explosivas en el interior de tanques de combustible, el modelado del proceso de combustión en su interior a partir de la ignición ante la presencia de una chispa o llama en el entorno de una abertura del tanque, así como las consecuencias de esta combustión (derivando en una posible explosión) sobre las personas en el entorno del tanque. Este trabajo fue realizado con la expectativa de hacer una contribución a la investigación de este tipo de accidentes no resueltos

    Modelling of Libyan crude oil using artificial neural networks

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    The preparation and analysis of input and model data was carried out. The importance of the correct technique of data filtering was highlighted with particular focus being emphasised on the removal of outliers in raw data. An important process in the use of Artificial Neural Network (ANN) models was identified as being the selection of the right input variables.A comparison between using factor analysis and statistical analysis in the selection of inputs and it was observed that the former gave significantly better results. The training and testing phase of Artificial Neural Network (ANN) model development was shown to be an important step in Artificial Neural Network (ANN) model development. If this phase was wrongly done then the ANN model would not be accurate in its predictions. Optimisation of the ANN model architecture was carried out with the amount of hidden layers, amount of neurons in the hidden layers, the transfer function used and the learning rate identified as key elements in obtaining an Artificial Neural Network (ANN) architecture that gave fast and accurate predictions. Fresh water addition and demulsifier addition were identified as key parameters in the economic performance of the desalting process. Due to a scarcity of water and the high cost of the demulsifier chemical it was important to try and optimise these two input variables thus reducing the cost of operations

    Advanced Testing and Characterization of Bituminous Materials, Two Volume Set

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    Bituminous materials are used to build durable roads that sustain diverse environmental conditions. However, due to their complexity and a global shortage of these materials, their design and technical development present several challenges. Advanced Testing and Characterisation of Bituminous Materials focuses on fundamental and performance testin

    Fundamentals of Delayed Coking Joint Industry Project

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    Advanced Testing and Characterization of Bituminous Materials, Two Volume Set

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    Bituminous materials are used to build durable roads that sustain diverse environmental conditions. However, due to their complexity and a global shortage of these materials, their design and technical development present several challenges. Advanced Testing and Characterisation of Bituminous Materials focuses on fundamental and performance testin

    Understanding Oxidative Aging of Asphalt Binder and it\u27s Effects on Cracking Susceptibility of Asphalt Mix

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    Every year around 400 million tons of asphalt mix is being laid in the United States and a significant portion of it is required for pavement rehabilitation. Cracking is one of the most common pavement distresses that is still not fully understood by the researchers. Very few states mandate tests for cracking resistance during the mix design phase; in addition, the test methods vary a lot from state to state. In the presence of oxygen, the asphalt binder over time undergoes chemical changes and becomes stiff which is known as oxidative aging that makes asphalt pavement more susceptible to cracking. Therefore, proper characterization of asphalt aging is a prerequisite to study the cracking mechanism of asphalt mix. In this dissertation, efforts are given for characterization of oxidative aging, investigation of the effect of aged binder on cracking susceptibility, and development of an antioxidant to reduce the aging-induced cracking. In this study, rheological characterization of laboratory aged binder and extracted binder from asphalt mix was performed using dynamic shear modulus of the binder to understand oxidative aging. Then the correlation between laboratory binder aging and binder aging in asphalt mix was established and a Rolling Thin Film Oven (RTFO) aging test protocol for warm mix asphalt (WMA) was developed. Another factor for cracking susceptibility of asphalt pavement is the excessive content of reclaimed asphalt pavement (RAP). RAP is added to the hot mix asphalt (HMA) for economic and environmental interest but the highly aged binder in RAP makes the mix stiffer and escalates the cracking. Because it is quick and simple, the viability of using a handheld Fourier Transformed Infrared (FT-IR) spectrometer was investigated to detect and quantify the aging of binder by measuring the absorbance intensity of carbonyl groups. An in-situ test method was developed to determine the reclaimed asphalt pavement (RAP) content in the plant mix using a handheld FT-IRS. The use of rejuvenators is the most suitable strategy to accommodate a higher amount of RAP in HMA and bio-based rejuvenators are of high interest. In this study, four types of cracking tests were performed on asphalt mix made with two different categories of rejuvenators: petroleum-based and bio-based oil. It was concluded that petroleum-based aromatic oil performed better to restore the cracking potential of the mix with high RAP content. Sound understanding of the cracking mechanism is necessary to find the right cracking susceptibility test for asphalt mix and design a cracking resistant mix. A finite element model of semi-circular bend (SCB) test of asphalt mix incorporating the cohesive zone material (CZM) model was performed using ANSYS to simulate and predict the fracture potential of asphalt mix as conducted in the laboratory according to ASTM D 8044 test method. The CZM properties of fine aggregate mastic (FAM) needed for ANSYS model of SCB test was determined by a laboratory double cantilever beam test and corresponding finite element model of double cantilever beam test., It was concluded that critical energy release rate (Jc) of asphalt mixture predicted from ANSYS model of SCB test was precise when compared with the laboratory SCB test of asphalt mix. Finally, locally sourced Lignin was used as an asphalt performance enhancer as well as an antioxidant. It was observed that lignin could improve the high-temperature performance grade of the binder and reduce the aging index. Mix made of lignin modified binder showed better cracking resistance by improving the flexibility index. Through this study, understanding oxidative aging helped with developing a revised short-term aging protocol for warm mix asphalt. One of the immediately implementable outcomes of this research is the in-situ application of handheld FT-IR spectrometer for quality control during the mix production at the plant through determining the reclaimed asphalt pavement content. This research will contribute to choosing suitable rejuvenators by understanding the cracking mechanism of asphalt mix through different tests. The finite element cohesive zone material model developed in this study can precisely predict fracture resistance of the mix in semicircular bending test by performing a double cantilever beam test of fine aggregate mastic. Viability of using bio based rejuvenator for RAP mixes and also the suitability of utilizing locally sourced lignin as an oxidant in asphalt binder were addressed in this research and the findings will help implement these environmentally friendly alternatives in resolving cracking related problems in asphalt pavements

    Processing of Heavy Crude Oils

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    Unconventional heavy crude oils are replacing the conventional light crude oils slowly but steadily as a major energy source. Heavy crude oils are cheaper and present an opportunity to the refiners to process them with higher profit margins. However, the unfavourable characteristics of heavy crude oils such as high viscosity, low API gravity, low H/C ratio, chemical complexity with high asphaltenes content, high acidity, high sulfur and increased level of metal and heteroatom impurities impede extraction, pumping, transportation and processing. Very poor mobility of the heavy oils, due to very high viscosities, significantly affects production and transportation. Techniques for viscosity reduction, drag reduction and in-situ upgrading of the crude oil to improve the flow characteristics in pipelines are presented in this book. The heavier and complex molecules of asphaltenes with low H/C ratios present many technological challenges during the refining of the crude oil

    Processing of Heavy Crude Oils

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    Unconventional heavy crude oils are replacing the conventional light crude oils slowly but steadily as a major energy source. Heavy crude oils are cheaper and present an opportunity to the refiners to process them with higher profit margins. However, the unfavourable characteristics of heavy crude oils such as high viscosity, low API gravity, low H/C ratio, chemical complexity with high asphaltenes content, high acidity, high sulfur and increased level of metal and heteroatom impurities impede extraction, pumping, transportation and processing. Very poor mobility of the heavy oils, due to very high viscosities, significantly affects production and transportation. Techniques for viscosity reduction, drag reduction and in-situ upgrading of the crude oil to improve the flow characteristics in pipelines are presented in this book. The heavier and complex molecules of asphaltenes with low H/C ratios present many technological challenges during the refining of the crude oil, such as heavy coking on catalysts. Hydrogen addition and carbon removal are the two approaches used to improve the recovery of value-added products such as gasoline and diesel. In addition, the heavy crude oil needs pre-treatment to remove the high levels of impurities before the crude oil can be refined. This book introduces the major challenges and some of the methods to overcome them

    Processing of Heavy Crude Oils

    Get PDF
    Unconventional heavy crude oils are replacing the conventional light crude oils slowly but steadily as a major energy source. Heavy crude oils are cheaper and present an opportunity to the refiners to process them with higher profit margins. However, the unfavourable characteristics of heavy crude oils such as high viscosity, low API gravity, low H/C ratio, chemical complexity with high asphaltenes content, high acidity, high sulfur and increased level of metal and heteroatom impurities impede extraction, pumping, transportation and processing. Very poor mobility of the heavy oils, due to very high viscosities, significantly affects production and transportation. Techniques for viscosity reduction, drag reduction and in-situ upgrading of the crude oil to improve the flow characteristics in pipelines are presented in this book. The heavier and complex molecules of asphaltenes with low H/C ratios present many technological challenges during the refining of the crude oil

    Investigation of the role of chemical composition on the weathering and emulsification behaviour of North Sea crude oil

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    The exploration, production, transportation and refining of petroleum often pose great technical and environmental challenges to the oil and gas industry. It is therefore extremely important to reliably predict and control fluid behaviour, in order to optimize production cost and for purposes of potential environmental pollution in the oil and gas operational activities. The investigations in this work focuses upon North Sea crude oils. In view of the fact that the North Sea crude oils are derived from the same source rock (Kimmeridge), they would be expected to have the same chemistry, but however, they tend to behave differently. The objectives of the research were to develop a better understanding of the effect of temperature and time on evaporation rate and its role in modifying the rate of weathering of North Sea crude oils on seawater. In this research, the chemistry of the oils was investigated to see the relationship to their emulsification behaviour. In the first part of this thesis, the weathering behaviour of four North Sea crude oils were investigated, in particular the evaporation, using a novel evaporation method. It was observed that the rate of evaporation varied between the North Sea oils. Evaporation of emulsified oil differed to unemulsified oil. North Sea crude oils of different states of weathering were emulsified and their viscosities and water contents measured. The four oils produced emulsion types of different viscosities and states of stability. The effects of degree of weathering of oils on emulsion states were assessed. The chemistry of the four North Sea crudes was investigated using a range of analytical techniques. The oils were fractionated by SARA analysis to produce saturates, aliphatic, resins and asphaltene fractions, prior to chemical analyses, using a range of analytical techniques (The crude oils were fractionated and the fractions analyzed for their chemical compositions). The compositions of the four crude oils differed to one another. From these analyses, a number of parameters were selected to characterize the oils. These were polarity, aromaticity and alkyl side chain. These data were used in a modeling study. The asphaltenes from the North Sea crudes investigated were substituted into both synthetic and model oils to study the effect on emulsification. It was observed that the asphaltenes had an effect on the emulsification behaviour. The behavior of modeled asphaltene structures based on the chemical characterization data was found to correlate with the emulsification behavior of the North Sea crudes investigatedAkwa Ibom State University of Technology (AKUTECH
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