Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Typescript. Includes abstract, computer source code, and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 328-337).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vii, 75 p. : ill. Includes abstract. Includes bibliographical references (p. 50-51).

Thesis (M.S. in Operations Research)--Naval Postgraduate School, March 2007. / Thesis Advisor(s): Daniel A. Nussbaum. "March 2007." Includes bibliographical references (p. 95-99). Also available in print.

Made available in DSpace on 2015-03-03T11:52:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-08-19Bitstream added on 2015-03-03T12:06:58Z : No. of bitstreams: 1 000807542.pdf: 1263932 bytes, checksum: 2637784563c12a1f4e37ed4e73907115 (MD5) / Nesse trabalho de tese, estuda-se a produção de biodiesel utilizando óleo de canola, buscandose minimizar o custo deste biocombustível, pela integração do processo de reforma a vapor da glicerina para produzir hidrogênio. Inicialmente, é feita uma revisão bibliográfica da produção de biodiesel num âmbito geral, seguida de um estudo sobre os aspectos gerais da produção da glicerina e suas aplicações. Estuda-se o processo de reforma a vapor da glicerina e suas condições de operação. Logo após, desenvolve-se uma simulação, através do software computacional ASPEN ONE HYSYS V8.0, aplicada a uma planta que produz 122,4 ton/ano de hidrogênio e 8096 ton/ano de biodiesel. A planta utiliza como insumos Ácido Fosfórico, Hidróxido de Sódio, Metanol, Gás Natural e Óleo de Canola e consome como utilidades Vapor de Água e Eletricidade. Em estapa posterior é efetuada uma análise exergética, na qual são determinadas as exergias de entrada e saída em cada componente da planta, além das irreversibilidades e rendimentos exergéticos associados. A análise permite qualificar e quantificar o máximo valor de energia útil aproveitado em cada componente conversor de energia do processo integrado de produção de biodiesel e hidrogênio. Posteriormente é aplicada a metodologia de análise funcional termoeconômica, que permite determinar os incrementos exergéticos e custos marginais de produção de biodiesel e de hidrogênio. Em última etapa, é realizada análise ecológica da planta (com ciclo de carbono e sem ciclo do carbono), considerando as emissões de gases do efeito estufa produzidas desde o plantio da canola até a extração e uso do óleo na planta de produção de biodiesel e hidrogênio. Na análise, são determinadas as emissões de poluentes, o dióxido de carbono equivalente, o indicador de poluição e a eficiência ... (Resumo completo, clicar acesso eletrônico abaixo) / this fuel by incorporation the process of glycerol steam reforming to produce hydrogen. Initially, a scientific review of biodiesel production is performed in a general context, followed by a study on the general aspects of the production of glycerin and its applications. The study of the process of glycerine steam reforming and its operating conditions. After that, a simulation is developed through the computer software ASPEN ONE HYSYS V8.0, applied to a plant that produces 122.4 tons / year of hydrogen and 8096 tons / year of biodiesel. The plant uses as inputs Phosphoric Acid, Sodium Hydroxide, Methanol, Natural Gas and Canola Oil and consumes as utilities Electricity and Water Steam. In the next topic, one exergy analysis is performed, in which are determined the input and output exergies in each component of the plant and the associated exergetic irreversibilities and efficiency. The analysis allows to qualify and quantify the maximum amount of useful energy in each component of the process. In another step, a methodology for thermoeconomic functional analysis is applied, for determination the exergetic increments and marginal production costs of biodiesel and hydrogen. In the final step, the ecological analysis of the plant is performed (with and without Carbon Cycle) considering the emissions of greenhouse gases produced from the planting to the extraction of canola and the use of its oil in biodiesel and hydrogen production plant. In this case the pollutants emissions, the equivalent carbon dioxide, the indicator of pollution and ecological efficiency of the plant are determined. This efficiency value is determined using a mathematical model obtained from the equation developed by Cardu e Baica (1999). Finally, it is concluded that the incorporation of the process of hydrogen production in a biodiesel plant is technically, economically and ... (Complete abstract click electronic access below)

Made available in DSpace on 2014-10-09T12:23:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:22Z (GMT). No. of bitstreams: 1 00324.pdf: 3506156 bytes, checksum: 9eb6171d89823f121dea681a04c09c5a (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Submitted in fulfillment of the requirements for the degree of Master of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2018. / Industrial development is associated with an increase in pollution levels and rising fuel prices. Research on clean energy contributes to reduction of fossil fuel dependency, decrease in ozone layer depletion and reduction in emission of toxic gases. The development of renewable energies increases the energy independence and reduces the impact of environmental pollution from fossil fuels. The biodiesel market is among the fastest growing renewable energy markets and its demand in the energy sector has tremendously increased over the last decade due to its environmental friendly qualities. Biodiesel is considered as a promising diesel fuel substitute based on the similarities of its properties with that of petroleum based diesel fuel. However, the high cost of the feedstock, environmental pollution as a result of wastewater generated from a homogeneous process has limited its full implementation. In addition, other technical challenges encountered during the production such as the immiscibility of the reagents and the reversibility of the transesterification reaction calls for innovative technologies to be developed. One promising solution to these issues is the use of membrane technology to serve as a reaction and separating medium for the production of biodiesel. This study is aimed at optimizing biodiesel production from vegetable oils using heterogeneous catalysts in a ceramic membrane. The objectives were to evaluate the performance of calcium oxide (CaO) as a catalyst supported on activated carbon in a membrane reactor for biodiesel production. Further still, to evaluate the membrane performance regarding permeate quality and to optimize the process using design of experiment. The final objective was to investigate the influence of operating parameters such as temperature, methanol/oil ratio, catalyst amount and reaction time on biodiesel yield. The transesterification of soya bean oil with methanol in the presence of a supported catalyst was carried out on a laboratory scale. The membrane reactor was designed and assembled for this purpose. The membrane reactor integrated many procedures such as combining reaction and separation in a single unit, continuous mixing of raw materials and maintaining high mass transfer between the immiscible phases during the reaction. The effect of the process parameters on the biodiesel production and FAME (fatty acid methyl ester) yields were investigated. One factor at a time (OFAT) experiments were conducted to identify the optimum range of the yield. The membrane reactor produced a permeate stream which separated at room temperature into a FAME rich non-polar phase and a methanol polar phase. The optimum range was between 90% - 94% within a reaction time of 60 – 180 minutes, methanol to oil ratio 3:1 - 9:1 and temperature range of 60 0C - 70 0C. Methyl ester produced met the ASTM D6751 and SANS 1935 specifications. The response surface methodology (RSM) based on the central composite design (CCD) was used to optimize the process. The optimization experiments were conducted around the optimum range established by the OFAT method. The optimum condition for transesterification of soya bean oil to fatty acid methyl ester was obtained at 3 g/L catalyst concentration, 65 0C temperature, 4.5:1 methanol to oil molar ratio and 90 minutes reaction time. At these optimum conditions, the FAME yield was 96.9 %, which is well within the yield of 97.7 % as predicted by the model. In conclusion, this work presents a study of high quality biodiesel production using a ceramic membrane reactor with the advantage of selectively permeating FAME and methanol. This study therefore showed that the use of a membrane for biodiesel production conserved water for other purposes; eliminates the purification step and wastewater generation thereby reducing the cost of biodiesel production. / M

Orientador: Flávio Junior Caires / Banca: Massao Ionashiro / Banca: Claudio Teodoro de Carvalho / Resumo: O biodiesel é um biocombustível que vem substituindo total ou parcialmente o diesel. A sua produção via catálise homogênea vem gerando diversos problemas durante a síntese e nos equipamentos industriais. A fim de solucionar os problemas apresentados pela catálise homogênea e encontrar condições de aplicações viáveis com catalisadores heterogêneos, o presente trabalho teve como objetivo preparar catalisadores heterogêneos a partir de selenatos de cálcio e de níquel suportados e não suportados em nanopartículas de zircônia e caracterizá-lo pelas técnicas TG-DTA, DSC, DSC-fotovisual, DRX, FTIR, MEV/MEV-FEG/TEM e EDS. A caracterização mostrou que a síntese de ZrO2 resultou em nanopartículas de diâmetro médio igual a (6,1 ± 1,1) nm, e a maioria destas nanopartículas encontraram-se na fase tetragonal. Já a caracterização dos selenatos mostrou que o CaSeO4 é dihidratado, enquanto que os compostos NiSeO4 e CaSeO4∙NiSeO4 são hexa e decahidratados, respectivamente. A síntese do material (CaSeO4∙NiSeO4) ∙10H2O resultou em uma mistura de fases, conforme evidenciado pelos resultados obtidos por TG-DTA, DSC, DSC-fotovisual, DRX e MEV; no entanto quando submetido ao aquecimento foi obtido um novo composto como produto de sua decomposição: CaNiO3. Tal resultado foi corroborado pelas técnicas TG-DTA, DRX, MEV e EDS. A impregnação dos selenatos na zircônia em meio etanólico ocorreu de forma satisfatória, como mostrado pelas técnicas TG-DTA e EDS, resultando em compostos cristalinos conforme ob... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The biodiesel is a biofuel which has been used as a partial or total substitute for diesel. Its production by homogeneous catalysis promotes several problems in the synthesis and in equipments. In order to solve the problems caused by homogeneous catalysis and find viable conditions using heterogeneous catalysts, this work aimed to prepare heterogeneous catalysts using calcium and nickel selenates supported and not supported in zirconia and characterize them using the techniques TG-DTA, DSC, DSC-fotovisual, DRX, FTIR, MEV / MEG-FEG / TEM and EDS. The characterization showed that the synthesis of ZrO2 resulted in nanoparticles of an average diameter equal to (6.1 ± 1.1) nm, and most of these nanoparticles were in the tetragonal phase. The characterization of the selenates showed that CaSeO4 is dihydrate, whereas the compounds NiSeO4 and CaSeO4∙NiSeO4 are hexa and decahydrated respectively. The synthesis of the material (CaSeO4∙NiSeO4) ∙10H2O resulted in a mixture of phases, as evidenced by the results obtained by TG-DTA, DSC, DSC-photovisual, XRD and MEV; However, when subjected to heating a new compound was obtained as product of its decomposition: CaNiO3. This result was corroborated by the TG-DTA, DRX, MEV and EDS techniques. The impregnation in ethanolic solution occurred satisfactorily, as shown by TG-DTA and EDS, and resulted in crystalline compounds such as observed by XRD. The catalysts were then applied in the production of biodiesel in laboratory scale, and the prod... (Complete abstract click electronic access below) / Mestre

>Magister Scientiae - MSc / Energy production from coal comes with an environmental cost because of the toxic waste produced during coal combustion such as coal ash and brine which are potential water and soil pollutants. Coal ash and brine contain toxic elements which can leach and contaminate soils and ground water if not properly disposed. This study investigated the mobility of species in coal fly ash co-disposed with brine at Sasol Secunda power station in order to establish if the ash dam could act as a salt sink. The ash was dumped as a slurry with 5:1 brine/ash ratio and the dam was in operation for 20 years. It was hypothesized that the disposed Secunda fly ash was capable of leaching toxic metal elements into the surrounding soils and ground water and therefore could not be used as a long term sustainable salt sink. Weathered fly ash samples were collected along a 51 m depth core at the Secunda ash dam by drilling and sampling the ash at 1.5 m depth intervals. A fresh fly ash sample was collected from the hoppers in the ash collection system at the power station. Characterization of both Secunda fresh ash and Secunda weathered ash core samples was done using X-ray diffraction (XRD) for mineralogy, X-ray fluorescence (XRF) for chemical composition and scanning electron microscopy (SEM) for morphology. Analysis of extracted pore water and moisture content determination of Secunda fresh ash and Secunda weathered ash core samples was done in order to evaluate the physico-chemical properties of the fly ash. The chemical partitioning and mobility of metal species in the ash dam was evaluated using the sequential extraction procedure. The XRD spectra revealed quartz, mullite and calcite as the dominant mineral phases in the weathered Secunda ash core samples while Secunda fresh ash contained quartz, mullite and lime. The major oxides identified by XRF analysis for both Secunda fresh ash and Secunda weathered ash include: SiO₂, Al₂O₃, CaO, Fe₂O₃, MgO, Na₂O, TiO₂ and K₂O. The minor oxides identified for both Secunda fresh ash and Secunda weathered ash were P₂O₅, SO₃ and MnO. The trace elements identified for both Secunda fresh ash and Secunda weathered ash were As, Ba, Ce, Co, Nb, Ni, Pb, Rb, Sr, V, Y, Zr and Th. However, U was detected in some of the Secunda weathered ash samples but not in Secunda fresh ash. Both Secunda fresh ash and Secunda weathered ash was classified as class F based on the sum of the oxides of silicon, aluminium and iron by mass and the CaO content as reported by XRF analysis, and further classified as sialic and ferrocalsialic type highlighting the significant levels of Si, Al, Ca and Fe in the fly ash based on XRF analysis. The XRF analysis further showed that brine codisposal on the ash may have been responsible for the slight enrichment of some species such as Na, SO₄²⁻, Mg, K and V in the disposed Secunda weathered fly ash. However, there was no significant accumulation of these species in the disposed fly ash despite continuous addition of an estimated 117.65 billion litres of brine over the 20 year period that the dam existed. Furthermore, Secunda ash dam showed an overall total salt capture capacity of only -0.01 weight %, a strong indication that the ash dam was incapable of holding salts and would release elements to the environment over time. The scanning electron microscopy (SEM) analysis revealed spherical particles with smooth outer surfaces for Secunda fresh ash while Secunda ash core samples consisted of agglomerated, irregular particles appearing to be encrusted, etched and corroded showing that weathering and leaching had occurred in the ash dam. A decrease in pH, electrical conductivity (EC) and total dissolved solids (TDS) was observed in Secunda ash core samples compared to Secunda fresh ash. While Secunda fresh ash (n = 3) had a pH of 12.38 ± 0.15, EC value of 4.98 ± 0.03 mS/cm and TDS value of 2.68 ± 0.03 g/L, the pH of Secunda ash core (n = 35) was 10.04 ± 0.50, the EC value was 1.08 ± 0.14 mS/cm and the TDS value was 0.64 ± 0.08 g/L. The lower pH in the ash dam created an environment conducive to the release of species through leaching, while the lower EC and TDS in the ash dam implied the loss of ionic species from the ash which resulted from leaching. The moisture content (MC) analysis indicated that Secunda ash dam was very damp with an average MC of 54.2 ± 12.66 % for Secunda ash core creating favourable conditions for leaching of species in the ash dam while Secunda fresh ash had MC of 1.8 ± 0.11 %. The bottom of Secunda ash dam appeared water logged which could cause slumping of the dam. The sequential extraction procedure revealed that the major and trace elements contained in both Secunda fresh fly ash and Secunda weathered fly ash could leach upon exposure to different environmental conditions. The elements showed partitioning between five geochemical phases i.e. water soluble fraction, exchangeable fraction, carbonate fraction, Fe & Mn fraction and residual fraction. The labile phases consisted of the water soluble fraction, exchangeable fraction and carbonate fraction. The % leached out in the labile phases was expressed as a fraction of each element‟s total content e.g. Si (6.15 %) meant that 6.15 % of the total amount of Si in the ash was released in the labile phases. Na was the most labile among the major elements in the ash dam while Si and Al which form the major aluminosilicate ash matrix also showed significant lability. The % leached out in the labile phases for these major elements was as follows: for Secunda fresh ash: Si (6.15 %), Al (7.84 %), Na (11.31 %); for weathered Secunda ash core samples (n = 35): Si (7.53 %), Al (8.12 %), Na (11.63 %). This study showed that the fly ash generated at Sasol Secunda power station could not be used as a long term sustainable salt sink. The wet disposal method used at Sasol Secunda power station poses a high risk of groundwater contamination due to the high liquid to solid ratio used to transport the ash for disposal, which may lead to rapid dissolution of all the soluble components in the fly ash. The large volumes of brine that pass through Secunda ash dam in the wet ash handling system present a greater environmental concern than the dry ash handling system which involves small amounts of brine entering the ash dump.

Made available in DSpace on 2015-07-13T12:10:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-11-05. Added 1 bitstream(s) on 2015-07-13T12:25:32Z : No. of bitstreams: 1 000835159.pdf: 413552 bytes, checksum: 8e2a2f82e97821d98b0a55768ba10124 (MD5) / A busca por sistemas sustentáveis somada à gradual redução das reservas de petróleo, alternativas produtivas vêm sendo estudadas, visando obter sistemas economicamente viáveis, socialmente justos, ecologicamente adequados e energicamente equilibrados. Uma destas alternativas é o biodiesel, sendo que, o pinhão manso, dentre as culturas energéticas apontadas com grande potencial produtivo de óleo para fins combustíveis, é que apresenta cenário mais positivo. O Pinhão Manso tem despertado muito interesse a nível internacional e no Brasil por seu alto conteúdo de óleo (38 a 48% na semente) e baixo custo de produção, entretanto existe ainda falta de informação tecnológica, tanto agronômica como genética. Esta falta de informação limita o aumento de competitividade. O presente trabalho tem como objetivo central realizar uma análise econômica e de investimentosna cultura do Pinhão Manso, na região de Selvíria - MS. Os dados foram levantados a partir dos experimentos de campo, de entrevistas com técnicos e da literatura. Para o cálculo dos custos foi utilizada a estrutura do custo operacional total e estimados indicadores de lucratividade. Para análise de investimentos foram estimados o valor presente líquido, a taxa interna de retorno e o valor anual equivalente. Os resultados mostram que produtor recupera o capital investido no 9o ano de produção. Muito embora a relação B/C tenha sido de 1,3, o que pode considerar que, no horizonte de 15 anos, a atividade é rentável ao produtor, pode-se dizer que a atividade não é uma boa opção de investimento já que a TIR foi de 14,03%, valor esse pouco atrativo. O VAE total foi de 360,93, por se tratar de um valor maior que zero, afirma-se que a alternativa é economicamente viável. Apesar dos avanços no cultivo do pinhão manso ainda demandam muitas pesquisas, relacionadas não apenas a questões técnica como adubação e manejo fitossanitário, mas também... / The search for sustainable systems coupled with the gradual reduction of oil reserves, alternatives production are being studied in order to obtain systems economically viable, socially just, ecologically appropriate and energetically balanced. One of these alternatives is biodiesel, and, Jatropha, among energy crops with great potential productive oil for fuel, is presenting more positive scenario. The Jatropha has attracted much interest internationally and in Brazil for its high oil content (38 to 48% in the seed) and low production cost, however there is still a lack of technological information, both genetic and agronomic. This lack of information limits the increase of competitiveness. The present study aims to conduct an economic and investment analysis of Jatropha in the region of Selvíria - MS. The data were collected from the field experiments, interviews with experts and literature. To calculate the costs was used the structure of total operating cost and estimated profitability indicators. For investment analysis were estimated net present value, internal rate of return and the annual value equivalent. The results show that producer retrieves the capital invested in the 9th year of production. Although the ratio B / C was of 1.3, which may consider that in the 15-year horizon, the activity is profitable to the producer, it can be said that the activity is not a good investment option since the IRR was of 14.03%, a value unattractive. The total EAV was 360.93, because it is a positive value it is stated that the alternative is economically viable. Despite advances in the cultivation of Jatropha still require much research, not only related to technical issues such as fertilization and pest management, but also socioeconomic