Made available in DSpace on 2014-10-09T12:24:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:03Z (GMT). No. of bitstreams: 1 00824.pdf: 1967504 bytes, checksum: 68fd26fd058a756733ba846201ba409c (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2014-10-09T12:24:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:03Z (GMT). No. of bitstreams: 1 00824.pdf: 1967504 bytes, checksum: 68fd26fd058a756733ba846201ba409c (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

This research project will investigate the potential business case and technical feasibility of using nuclear generated heat in a crude oil refinery located some distance away. The key design element is an energy transportation mechanism that doesn’t compromise the safety, licensing or operability of the nuclear plant. In a crude oil refinery processing heat is generated by combusting fuels that are generally sellable products. The inherent safety features and high output temperature of a HTGR make it an appropriate replacement heat source for such a processing plant. An opportunity thus exists to replace the refinery hydrocarbon fuel usage with nuclear energy thereby improving refinery profitability. Three alternate proposed were generated. Alt 1: Generation of steam at HTGR, piped to the refinery to replace current supply. Alt 2: Closed loop reversible methanation reaction delivering potential chemical energy to the refinery which is released to the process in heat exchangers. Alt 3: Hydrogen production from water splitting at the HTGR, piped to the refinery and combusted in boilers or used for hydrotreating diesel. Utilizing data from refinery plant historian and journals, a basic engineering study assessed technical feasibility thereof. An economic model for the 2 most promising alternates was set up using quotations and factored data and evaluated against the existing refinery situation. A consistently increasing crude price was assumed. Alternates 1, 2 and 3 proved technically feasible and delivered 86 MW, 59 MW and 48MW to the refinery respectively. Generating steam at the HTGR (Alt 1) demonstrated an attractive business case, strengthened by co-locating the nuclear plant at the refinery. It is therefore concluded that using a HTGR for process heat in a petrochemical plant such as a refinery is techno-economically practical and demands further consideration. If future carbon emission legislation is promulgated this proposal will be key component of the solution. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

This research project will investigate the potential business case and technical feasibility of using nuclear generated heat in a crude oil refinery located some distance away. The key design element is an energy transportation mechanism that doesn’t compromise the safety, licensing or operability of the nuclear plant. In a crude oil refinery processing heat is generated by combusting fuels that are generally sellable products. The inherent safety features and high output temperature of a HTGR make it an appropriate replacement heat source for such a processing plant. An opportunity thus exists to replace the refinery hydrocarbon fuel usage with nuclear energy thereby improving refinery profitability. Three alternate proposed were generated. Alt 1: Generation of steam at HTGR, piped to the refinery to replace current supply. Alt 2: Closed loop reversible methanation reaction delivering potential chemical energy to the refinery which is released to the process in heat exchangers. Alt 3: Hydrogen production from water splitting at the HTGR, piped to the refinery and combusted in boilers or used for hydrotreating diesel. Utilizing data from refinery plant historian and journals, a basic engineering study assessed technical feasibility thereof. An economic model for the 2 most promising alternates was set up using quotations and factored data and evaluated against the existing refinery situation. A consistently increasing crude price was assumed. Alternates 1, 2 and 3 proved technically feasible and delivered 86 MW, 59 MW and 48MW to the refinery respectively. Generating steam at the HTGR (Alt 1) demonstrated an attractive business case, strengthened by co-locating the nuclear plant at the refinery. It is therefore concluded that using a HTGR for process heat in a petrochemical plant such as a refinery is techno-economically practical and demands further consideration. If future carbon emission legislation is promulgated this proposal will be key component of the solution. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The escalating energy prices and the increasing environmental impact posed by the industrial usage of energy have spurred industry to adopt various approaches to conserving energy and mitigating negative environmental impact. This work aims at developing a systematic approach to integrate solar energy into industrial processes to drive thermal energy transfer systems producing power, cool, and heat. Solar energy is needed to be integrated with other different energy sources (biofuels, fossil fuels, process waste heat) to guarantee providing a stable energy supply, as industrial process energy sources must be a stable and reliable system. The thermal energy transform systems (turbines, refrigerators, heat exchangers) must be selected and designed carefully to provide the energy demand at the different forms (heat, cool, power). This dissertation introduces optimization-based approaches to address the following problems: • Design of cogeneration systems with solar and fossil systems • Design and integration of solar-biofuel-fossil cogeneration systems • Design of solar-assisted absorption refrigeration systems and integration with the processing facility • Development of thermally-coupled dual absorption refrigeration systems, and • Design of solar-assisted trigeneration systems Several optimization formulations are introduced to provide methodical and systematic techniques to solve the aforementioned problems. The approach is also sequenced into interacting steps. First, heat integration is carried out to minimize industrial heating and cooling utilities. Different forms of external-energy sources (e.g., solar, biofuel, fossil fuel) are screened and selected. To optimize the cost and to overcome the dynamic fluctuation of the solar energy and biofuel production systems, fossil fuel is used to supplement the renewable forms of energy. An optimization approach is adopted to determine the optimal mix of energy forms (fossil, bio fuels, and solar) to be supplied to the process, the system specifications, and the scheduling of the system operation. Several case studies are solved to demonstrate the effectiveness and applicability of the devised procedure. The results show that solar trigeneration systems have higher overall performance than the solar thermal power plants. Integrating the absorption refrigerators improves the energy usage and it provides the process by its cooling demand. Thermal coupling of the dual absorption refrigerators increases the coefficient of performance up to 33 percent. Moreover, the process is provided by two cooling levels.

Laser cutting is a widely used technology for precision cutting of various materials, in-cluding mild structural steel. It involves the use of a high-powered laser beam to melt, burn, or vaporize the material, resulting in a clean and accurate cut. This doctoral thesis presents a comprehensive investigation of the laser cutting process for mild structural steels. To understand the thermal effects on the steel workpiece, an analytical model for the laser cutting heat source is proposed, which takes into account laser source geometry variation along the cut edge thickness. A modified heat source based on a Gaussian dis-tribution is used to model the heat flux as a combination of laser beam and heat produced by the reaction of oxygen with iron. The proposed model allows the laser cutting process to be simulated as a function of cutting speed, laser power, and shape of the heat flux. The FE method is employed to predict both temperature and stress fields in the cutting section considering the solid-state phase transformation during and after the laser cutting process. Optical microscopy, scanning electron microscopy and microhardness measure-ments are employed to observe morphological and metallurgical changes in the cutting sections, and the stress is detected using the X-ray diffraction methodology. The residual stress field surrounding the cutting edges is experimentally examined, and the results are compared to those anticipated by the developed model. An accurate temperature distri-bution field is obtained and validated by microstructural solid phases of the cut specimens. Consequently, residual stresses are also validated by comparing experimental measure-ments and outputs of the FE model. The study also investigates the optimization of laser cutting parameters for achieving, in agreement with the standard EN ISO 9013, quality cut surface requirements, such as roughness and perpendicularity. The trial-and-error method used in the past is incompat-ible with environment-friendly processes. Hence, to study the effects of cutting parameters on the target parameters and to collect data, an experimental campaign is carried out on a 12 mm thickness low carbon steel grade S235 cut by a 4kW fiber laser. A multi-objective optimization based on both a genetic algorithm and Kriging method is carried out to in-vestigate the correlations between input and target parameters as well as to find the op-timal laser cutting parameters to achieve the minimum roughness and perpendicularity. The applicability of the Kriging method to laser cutting processes is highlighted by the agreement between predicted cut quality and experimental results, provided by additional specimens cut with laser parameter sets obtained by a Pareto front. Overall, the investi-gated model offers important details on the physical procedures that occur during the laser cutting process and provides useful insights for selecting the optimal sets of laser cutting parameters for different applications.

With the rising electricity, raw material and fossil fuel prices, as well as the relatively low selling price of steel, the steel industry has been put under strain to produce steel as cost–effectively as possible. Ideally the industry requires a cost–effective, stable source of energy to cater for its electricity and energy needs. Modern High Temperature Reactors are in a position to provide industries with not only electricity, but also process heat. Therefore, a study was conducted into the economic viability of centering the steel industry on nuclear power. This study considered 3 technology options: a nuclear facility to cater for solely the electricity needs of the steel industry; a nuclear facility producing hydrogen for the process needs of the steel industry; and a nuclear facility co–generating electricity and process heat for the steel industry. An economic model for each of the 3 scenarios was developed that factored in the various cost considerations for each of the 3 options. In general, this included the construction costs, operational and maintenance cost, build time and interest rate of the financed amount. For each option, the model calculated the cost of production per unit output. The outputs were electricity for option 1, hydrogen for option 2, and both electricity and process heat for option 3. Each model was optimised based on a realistic best case scenario for the capital and operational costs and respective best case cost per unit outputs for each of the options were calculated. Using the optimised cost model, it was shown that electricity produced from nuclear power was more cost effective than current electricity prices in South Africa. Similarly, it was shown that a nuclear facility could produce heat at a more cost–effective means than by the combustion of natural gas. Hydrogen proved to be not cost effective compared to reformed natural gas as a reducing agent for iron ore. Based on the cost savings, a cash–flow analysis showed that the payback period for a nuclear power plant that produced electricity for the steel industry would be around 12 years at 0% interest and 15 years at 5% interest. Due to the long payback period and lack of certainty in the steel industry, any steel manufacturer would opt for purchasing electricity from a nuclear based electricity utility rather than building a facility themselves. Savings of over $70 million/year were achievable for a 2 million tonne/year electric arc furnace. Overall this analysis showed that electricity generation is the only viable means for nuclear power to be integrated with the steel manufacturing industry. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.

With the rising electricity, raw material and fossil fuel prices, as well as the relatively low selling price of steel, the steel industry has been put under strain to produce steel as cost–effectively as possible. Ideally the industry requires a cost–effective, stable source of energy to cater for its electricity and energy needs. Modern High Temperature Reactors are in a position to provide industries with not only electricity, but also process heat. Therefore, a study was conducted into the economic viability of centering the steel industry on nuclear power. This study considered 3 technology options: a nuclear facility to cater for solely the electricity needs of the steel industry; a nuclear facility producing hydrogen for the process needs of the steel industry; and a nuclear facility co–generating electricity and process heat for the steel industry. An economic model for each of the 3 scenarios was developed that factored in the various cost considerations for each of the 3 options. In general, this included the construction costs, operational and maintenance cost, build time and interest rate of the financed amount. For each option, the model calculated the cost of production per unit output. The outputs were electricity for option 1, hydrogen for option 2, and both electricity and process heat for option 3. Each model was optimised based on a realistic best case scenario for the capital and operational costs and respective best case cost per unit outputs for each of the options were calculated. Using the optimised cost model, it was shown that electricity produced from nuclear power was more cost effective than current electricity prices in South Africa. Similarly, it was shown that a nuclear facility could produce heat at a more cost–effective means than by the combustion of natural gas. Hydrogen proved to be not cost effective compared to reformed natural gas as a reducing agent for iron ore. Based on the cost savings, a cash–flow analysis showed that the payback period for a nuclear power plant that produced electricity for the steel industry would be around 12 years at 0% interest and 15 years at 5% interest. Due to the long payback period and lack of certainty in the steel industry, any steel manufacturer would opt for purchasing electricity from a nuclear based electricity utility rather than building a facility themselves. Savings of over $70 million/year were achievable for a 2 million tonne/year electric arc furnace. Overall this analysis showed that electricity generation is the only viable means for nuclear power to be integrated with the steel manufacturing industry. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.

Este trabalho tem por objetivo analisar as perspectivas dos gases combustíveis como energia final para a obtenção de energia útil, em aquecimento direto (AD) e calor de processo (CP), identificando e quantificando potenciais como alternativa da eletrotermia. São comparados dois panoramas na avaliação das economias de energia primária pela substituição da eletrotermia: o primeiro considerando que a energia substituída oriunda de energéticos do parque gerador; e o segundo levando em conta que a redução se refletiu nas termelétricas. Para atingir este objetivo, o trabalho se inicia com uma revisão bibliográfica, onde são tratados os aspectos necessários para um melhor entendimento do texto, com os conceitos de eletrotermia, calor e termodinâmica, seguindo-se um capítulo destinado aos gases combustíveis, suas características e disponibilidade futura para a conversão. As informações básicas para a análise dos potenciais nos setores foram tomadas a partir do último Balanço de Energia Útil, além de trabalhos desenvolvidos no mercado industrial pelo autor. O trabalho discorre também sobre configurações tecnológicas usadas nas conversões, incluindo os custos envolvidos. Na conclusão, os cálculos mostraram que significativas economias de energia primária podem ser obtidas com a conversão da eletrotermia para gases combustíveis no setor industrial brasileiro, considerando a eletricidade produzida a partir de plantas termelétricas. / This paper aims to analyze the prospects of fuel gases as final energy in order to get useful energy in direct heating and process heat, identifying and qualifying potentials as the alternative of electrothermy. Two panoramas are compared in the evaluation of primary energy displacement: the first one considering the replaced energy coming from energy generating facilities and the second taking into account that the reduction was reflected in thermoelectric power plants. To achieve this goal, the work begins with a literature review which covers the aspects needed for a better understanding of the text, with the concepts of electrothermy, heat and thermodynamics, followed by a chapter intended for fuel gases, their characteristics and future readiness for conversion. The basic information for the analysis of potential sectors were taken for the last Useful Energy Balance, and work undertaken by the author in the industrial market. The paper also discourses about technological configurations used in conversions, including also the costs involved. In conclusion, the calculations showed that significant primary energy savings can be obtained through the conversion of electrothermy by fuel gases in the Brazilian industrial sector, taking into account the electricity produced from thermoelectric power plants.

Este trabalho tem por objetivo analisar as perspectivas dos gases combustíveis como energia final para a obtenção de energia útil, em aquecimento direto (AD) e calor de processo (CP), identificando e quantificando potenciais como alternativa da eletrotermia. São comparados dois panoramas na avaliação das economias de energia primária pela substituição da eletrotermia: o primeiro considerando que a energia substituída oriunda de energéticos do parque gerador; e o segundo levando em conta que a redução se refletiu nas termelétricas. Para atingir este objetivo, o trabalho se inicia com uma revisão bibliográfica, onde são tratados os aspectos necessários para um melhor entendimento do texto, com os conceitos de eletrotermia, calor e termodinâmica, seguindo-se um capítulo destinado aos gases combustíveis, suas características e disponibilidade futura para a conversão. As informações básicas para a análise dos potenciais nos setores foram tomadas a partir do último Balanço de Energia Útil, além de trabalhos desenvolvidos no mercado industrial pelo autor. O trabalho discorre também sobre configurações tecnológicas usadas nas conversões, incluindo os custos envolvidos. Na conclusão, os cálculos mostraram que significativas economias de energia primária podem ser obtidas com a conversão da eletrotermia para gases combustíveis no setor industrial brasileiro, considerando a eletricidade produzida a partir de plantas termelétricas. / This paper aims to analyze the prospects of fuel gases as final energy in order to get useful energy in direct heating and process heat, identifying and qualifying potentials as the alternative of electrothermy. Two panoramas are compared in the evaluation of primary energy displacement: the first one considering the replaced energy coming from energy generating facilities and the second taking into account that the reduction was reflected in thermoelectric power plants. To achieve this goal, the work begins with a literature review which covers the aspects needed for a better understanding of the text, with the concepts of electrothermy, heat and thermodynamics, followed by a chapter intended for fuel gases, their characteristics and future readiness for conversion. The basic information for the analysis of potential sectors were taken for the last Useful Energy Balance, and work undertaken by the author in the industrial market. The paper also discourses about technological configurations used in conversions, including also the costs involved. In conclusion, the calculations showed that significant primary energy savings can be obtained through the conversion of electrothermy by fuel gases in the Brazilian industrial sector, taking into account the electricity produced from thermoelectric power plants.