Master of Science in Sustainable Process Development

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Browsing Master of Science in Sustainable Process Development by Author "Gunasekera, MY"

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    item: Thesis-Full-text
    Assessment of environmental impact for accidental release of heavy gas
    Gunawardena, YN; Gunasekera, MY; Narayan, M
    An air dispersion model can be used to mathematically simulate air pollutants dispersion in the ambient atmosphere. These dispersion results can be used to predict their environmental impact, concentrations and movement. Such predicted data of hazardous gases released after a chemical accident are valuable since it can be used to provide timely information to emergency response providers as well as to make decisions on siting chemical plants at safe distances from settlements during plant development stages. Dense gas dispersion is the focus of this research as several pressurized dense gas release accidents have happened during the last few years in this country. These gases form clouds heavier than air when released to the atmospheric environment. In this study a mathematical model for the dispersion of heavy gas due to an accidental release is presented in order to determine the environmental impact. The heavy gas model was then used to simulate the dispersion of negatively buoyant and highly toxic chlorine gas to illustrate the use of heavy gas dispersion modeling in hazard analysis. A worst case scenario study with stability class A, was used for an accidental release of 900kg of chlorine from a location in Kaluthara district in Sri Lanka. To determine the impact of the release probit analysis, safe distance and hazardous time period calculations were done. From the model results, for a 900kg chlorine release, safe Immediately Dangerous to Life or Health (IDLH) distance was above 490m. Within this hazardous zone the safe time period starts after 5.44 minutes from the release. Further, this model can be used to predict information, such as concentration variation of the substance released with time and, cloud dimensions such as height and radius. For validation, experimental data in literature were collected and a sensitivity analysis was done to identify the best values for the model parameters.
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    item: Thesis-Abstract
    Chemical process route selection based on assessment of inherent environmental hazard, occupational health and safety
    (2015-03-01) Warnasooriya, S; Gunasekera, MY
    Chemical process route selection is one of the main design decisions that needs to be taken during the preliminary stages of chemical plant design and development. A chemical process route is considered as the raw materials and the sequence of reaction steps that converts them in to desired products. Previously, the most important factor considered in selecting the chemical process route was plant economics. However, now other issues such as safety, environment and occupational health have also become important considerations. Therefore, at early stages of chemical process plant design and development it is necessary to apply methodologies to identify and assess environmental, occupational health and safety hazards involved in the process routes. This work proposes a methodology for assessing chemical process routes to manufacture a chemical based on inherent environmental, occupational health and safety hazards. The method developed in this work can be used during early design stages of a chemical process plant. The process route selection is done based on impacts due to emissions from the ongoing operational conditions of the plant. It considers the potential toxicological impacts on the environment, potential impacts on the occupational health due to fugitive emissions and the potential chemical and process safety impacts within the plant. As the outcome of the methodology, an integrated index called “Inherent Chemical Process Route Index” (ICPRI) is proposed which can be used for the selection of the ‘best’ chemical process route for a chemical process plant, based on inherent environmental hazard, occupational health and safety (IEHS). The lower the ICPRI the more inherently environmentally friendly, inherently occupational healthier and inherently safer the route is. The methodology developed in this work can also rank alternative chemical process routes based on inherent environmental hazard or occupational health hazard and or safety hazard separately. The method was applied on four possible process routes to produce acetone. The propene oxidation route showed the lowest ICPRI value indicating potentially the ‘best’ chemical process route for acetone manufacturing process based on the IEHS assessment. Keywords: Inherent Environmental hazard, occupational health, Inherent Safety, Chemical process route