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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Middle distillate hydrotreatment zeolite catalysts containing Pt/Pd or Ni

Marin-Rosas, Celia 15 May 2009 (has links)
A study on middle distillate hydrotreatment zeolite catalysts containing Pt/Pd and/or Ni was performed. The effect of the addition of the corresponding CoMo, CoMoPd, CoMoPtPd and CoMoNi in PdNiPt-zeolite, Pt-zeolite, Ni-zeolite, and PdPt-zeolite was studied. The catalysts were characterized physically and chemically by methods and techniques such as Brunauer-Emmett-Teller (BET), Barret-Joyner-Hallenda (BJH), and neutron activation analysis. The structures of the Ni and Pt containing zeolite were studied by X-ray Photoelectron Spectroscopy (XPS). An experimental apparatus was constructed to investigate the activity of the experimental catalysts. The catalysts activity measured in terms of conversion of dibenzothiophene (DBT), substituted dibenzothiophenes (sDBT) and phenanthrene as well as molar-averaged conversion was evaluated in a continuous flow Robinson Mahoney reactor with stationary basket in the hydrodesulfurization and hydrogenation of heavy gas oil which contains sulphur refractory compounds such as 4- methyldibenzotiophene (4-MDBT) and 4,6- dimethyldibenzothiophene (4,6-DMDBT). DBT, 4-MDBT, 3-MDBT, 1-EDBT, 3-EDBT, 4,6-DMDBT, 3,6-DMDBT, 2,8- DMDBT and 4-methylnaphtho[2,1-b]thiophene were selected to calculate the molaraveraged conversion. The conversions of the sulfur containing compounds and phenanthrene were determined as a function of the operating variables: space time (W/Fo DBT), temperature, H2/HC mol ratio and pressure. The Conversions of DBT and 4,6-DMDBT into their reaction products such as Biphenyl (BPH), Cyclohexylbenzene (CHB), Bicyclohexyl (BCH) and 3,4-Dimethylbiyphenyl (3,4-DMBPH) were determined only as a function of space time in the interval of 4000-6000 kgcath/kmol. The results of this work showed that Pt-HY and PdPt-HY are good noble metals catalysts for the hydrodesulfurization of heavy gas oil. Moreover, this study showed that CoMoPd/Pt-HY and CoMoNi/PdPt-HY catalysts are good candidates for deep HDS and hydrogenation of heavy gas oil. It was found that the conversions of sulfur compounds were higher than the conversions provided by the conventional CoMo/Al2O3 catalyst. Also higher hydrogenation of phenanthrene was observed. Deactivation of the catalysts was not observed during the operation. Finally, the study not only contributed to define the technical bases for the preparation of the noble metal catalysts for hydrodesulfurization of heavy gas oil at pilot scale, but also provided technical information for developing the kinetic modeling of the hydrodesulfurization of heavy gas oil with the noble metal catalysts.
2

Análise crítica do ensaio NACE TM-0172 para verificação da agressividade de derivados de petróleo. / Critical analysis of the NACE TM-0172 test to verify the corrosive properties of distillate fuels.

Nagayassu, Vanessa Yumi 08 May 2006 (has links)
Antes de transportar os derivados de petróleo por dutos, a sua corrosividade é verificada por meio do ensaio NACE TM-0172 ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). O referido ensaio, por basear-se na avaliação visual, não tem por objetivo a determinação da taxa de corrosão e nem a verificação do tipo de corrosão e, normalmente, os profissionais que o executam não têm conhecimento da influência das variáveis que interferem nos resultados do ensaio. Desta forma, o presente estudo teve como objetivos: verificar a influência de algumas variáveis (velocidade de agitação, geometria do corpo-deprova, temperatura, teor de água, tempo de ensaio e pH) nos resultados obtidos com o ensaio NACE TM-0172 (NACE, 2001), fazer avaliação quantitativa da taxa de corrosão por meio da determinação da perda de massa dos corpos-de-prova expostos ao meio, correlacionar os resultados da avaliação visual com a perda de massa, verificar se o ensaio, que é realizado em condições aeradas, simula adequadamente as condições internas dos dutos. Para condução do estudo, além do próprio ensaio NACE TM-0172 (NACE, 2001), foram realizados outros ensaios simples utilizando o aço-carbono COPANT 1020 na confecção dos corpos-de-prova metálicos. Com base em todos os ensaios realizados, foi possível fazer uma análise crítica do ensaio NACE TM-0172 (NACE, 2001) e justificar a adoção das diferentes condições de ensaio além de apresentar uma explicação para o mecanismo de corrosão do açocarbono na mistura derivado/água. / Before transporting distillate fuels by pipelines, their corrosive properties are verified by the NACE TM-0172 test ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). This test, being based on a visual evaluation, has as its goal, neither the determination of the corrosion rate nor the verification of the corrosion type; the technicians usually do not know the influence of the variables that interfere in the test results. Thus, this study had as its goals: to verify the influence of some variables (stirring speed, coupon geometry, temperature, water content, test duration and pH of the water phase) in the results obtained with the NACE TM-0172 test (NACE, 2001), to make the quantitative evaluation of the corrosion rate by determination of the coupon mass loss exposed to this condition, to correlate the results of the visual evaluation with the mass loss, to verify if the test, which is made in aerated conditions, simulate properly the internal conditions of pipelines. To conduct the study, besides the NACE TM-0172 (NACE, 2001) test itself, other simple tests were made using the carbon steel COPANT 1020 to prepare the metallic coupons. Based on all the tests, it was possible to make a critical analysis of the NACE TM-0172 (NACE, 2001) test and (to) justify the adoption of different test conditions as well as there being the possibility of presenting an explanation for the mechanism of the carbon steel corrosion in the mixture distillate/water.
3

Análise crítica do ensaio NACE TM-0172 para verificação da agressividade de derivados de petróleo. / Critical analysis of the NACE TM-0172 test to verify the corrosive properties of distillate fuels.

Vanessa Yumi Nagayassu 08 May 2006 (has links)
Antes de transportar os derivados de petróleo por dutos, a sua corrosividade é verificada por meio do ensaio NACE TM-0172 ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). O referido ensaio, por basear-se na avaliação visual, não tem por objetivo a determinação da taxa de corrosão e nem a verificação do tipo de corrosão e, normalmente, os profissionais que o executam não têm conhecimento da influência das variáveis que interferem nos resultados do ensaio. Desta forma, o presente estudo teve como objetivos: verificar a influência de algumas variáveis (velocidade de agitação, geometria do corpo-deprova, temperatura, teor de água, tempo de ensaio e pH) nos resultados obtidos com o ensaio NACE TM-0172 (NACE, 2001), fazer avaliação quantitativa da taxa de corrosão por meio da determinação da perda de massa dos corpos-de-prova expostos ao meio, correlacionar os resultados da avaliação visual com a perda de massa, verificar se o ensaio, que é realizado em condições aeradas, simula adequadamente as condições internas dos dutos. Para condução do estudo, além do próprio ensaio NACE TM-0172 (NACE, 2001), foram realizados outros ensaios simples utilizando o aço-carbono COPANT 1020 na confecção dos corpos-de-prova metálicos. Com base em todos os ensaios realizados, foi possível fazer uma análise crítica do ensaio NACE TM-0172 (NACE, 2001) e justificar a adoção das diferentes condições de ensaio além de apresentar uma explicação para o mecanismo de corrosão do açocarbono na mistura derivado/água. / Before transporting distillate fuels by pipelines, their corrosive properties are verified by the NACE TM-0172 test ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). This test, being based on a visual evaluation, has as its goal, neither the determination of the corrosion rate nor the verification of the corrosion type; the technicians usually do not know the influence of the variables that interfere in the test results. Thus, this study had as its goals: to verify the influence of some variables (stirring speed, coupon geometry, temperature, water content, test duration and pH of the water phase) in the results obtained with the NACE TM-0172 test (NACE, 2001), to make the quantitative evaluation of the corrosion rate by determination of the coupon mass loss exposed to this condition, to correlate the results of the visual evaluation with the mass loss, to verify if the test, which is made in aerated conditions, simulate properly the internal conditions of pipelines. To conduct the study, besides the NACE TM-0172 (NACE, 2001) test itself, other simple tests were made using the carbon steel COPANT 1020 to prepare the metallic coupons. Based on all the tests, it was possible to make a critical analysis of the NACE TM-0172 (NACE, 2001) test and (to) justify the adoption of different test conditions as well as there being the possibility of presenting an explanation for the mechanism of the carbon steel corrosion in the mixture distillate/water.
4

Bränsleövergångar : <em>Miljölagstiftningarnas inverkan på fartygsdriften</em>

Nilsson, Andreas, Mikkelsen, Mattias, Westberg, Jacob January 2010 (has links)
<p>Under vårt sista år var vi intresserade av att ta reda på de problem som vi kan stöta på i våra yrkesroller som fartygsingenjörer. Arbetet tar upp de tekniska problem som uppstår p.g.a. de allt strängare kraven på minskade svavelutsläpp från fartyg. De tekniska problemen härstammar från de olika bränslekvaliteternas vitt skilda egenskaper. Som svar på dessa problem har det utvecklats tekniska lösningar varav två stycken har tagits upp i detta arbete.</p><p>För att ta reda på vilka tekniska problem som kan uppstå tog vi del av den berörda utrustningens tillverkares erfarenheter enligt empirisk modell. Enligt samma modell har vi även utfört en kvalitativ intervju med en teknisk chef för att ta del av dennes erfarenheter.</p><p>Miljölagarna rörande luftföroreningar från fartyg kommer med tiden stramas åt allt mer, varpå de kommer få en än mer betydande inverkan på fartygsdriften i framtiden. Bränsleövergångar ombord kommer att bli ett mer frekvent inslag då destillatbränslen krävs för att följa vissa områdens utsläppsregler men samtidigt nyttja tjockolja i så stor utsträckning som möjligt av ekonomiska skäl.</p> / <p>During our final year, we developed an interest in the difficulties we may encounter as marine engineers. This diploma thesis concerns the technical issues that occur due to new regulations concerning the sulphur emissions from merchant vessels. These technical issues are a consequence of the vast property differences between fuel qualities. As a result of these problems, technical solutions have been developed as a countermeasure, of which two have been presented in this comprehensive report.</p><p>In order to identify the difficulties that may arise we analysed the manufacturers experiences in an empirical method. Using the same method we conducted an in-depth interview with a chief engineer in order to take part of his experiences.</p><p>The environmental legislation concerning air pollution from merchant vessels will in a near future be even stricter, thus they will have an increasing impact on the ships operation. Fuel change-overs will be a more frequent event as in some areas distillate fuels are required to meet the demands on low sulphur emissions. At the same time the economical advantages of heavy fuel oil makes it preferable to use in other areas.</p>
5

Bränsleövergångar : Miljölagstiftningarnas inverkan på fartygsdriften

Nilsson, Andreas, Mikkelsen, Mattias, Westberg, Jacob January 2010 (has links)
Under vårt sista år var vi intresserade av att ta reda på de problem som vi kan stöta på i våra yrkesroller som fartygsingenjörer. Arbetet tar upp de tekniska problem som uppstår p.g.a. de allt strängare kraven på minskade svavelutsläpp från fartyg. De tekniska problemen härstammar från de olika bränslekvaliteternas vitt skilda egenskaper. Som svar på dessa problem har det utvecklats tekniska lösningar varav två stycken har tagits upp i detta arbete. För att ta reda på vilka tekniska problem som kan uppstå tog vi del av den berörda utrustningens tillverkares erfarenheter enligt empirisk modell. Enligt samma modell har vi även utfört en kvalitativ intervju med en teknisk chef för att ta del av dennes erfarenheter. Miljölagarna rörande luftföroreningar från fartyg kommer med tiden stramas åt allt mer, varpå de kommer få en än mer betydande inverkan på fartygsdriften i framtiden. Bränsleövergångar ombord kommer att bli ett mer frekvent inslag då destillatbränslen krävs för att följa vissa områdens utsläppsregler men samtidigt nyttja tjockolja i så stor utsträckning som möjligt av ekonomiska skäl. / During our final year, we developed an interest in the difficulties we may encounter as marine engineers. This diploma thesis concerns the technical issues that occur due to new regulations concerning the sulphur emissions from merchant vessels. These technical issues are a consequence of the vast property differences between fuel qualities. As a result of these problems, technical solutions have been developed as a countermeasure, of which two have been presented in this comprehensive report. In order to identify the difficulties that may arise we analysed the manufacturers experiences in an empirical method. Using the same method we conducted an in-depth interview with a chief engineer in order to take part of his experiences. The environmental legislation concerning air pollution from merchant vessels will in a near future be even stricter, thus they will have an increasing impact on the ships operation. Fuel change-overs will be a more frequent event as in some areas distillate fuels are required to meet the demands on low sulphur emissions. At the same time the economical advantages of heavy fuel oil makes it preferable to use in other areas.
6

Barriers to a biofuels transition in the U.S. liquid fuels sector

O'Donnell, Michael Joseph 05 August 2010 (has links)
Demand for liquid fuels (i.e., petroleum products) has burdened the U.S. with major challenges, including national security and economic concerns stemming from rising petroleum imports; impacts of global climate change from rising emissions of CO2; and continued public health concerns from criteria and hazardous (i.e., toxic) air pollutants. Over the last decade or so, biofuels have been touted as a supply-side solution to several of these problems. Biofuels can be produced from domestic biomass feedstocks (e.g., corn, soybeans), they have the potential to reduce GHG emissions when compared to petroleum products on a lifecycle basis, and some biofuels have been shown to reduce criteria air pollutants. Today, there are numerous policy incentives—existing and proposed—aimed at supporting the biofuels industry in the U.S. However, the Renewable Fuel Standard (RFS) Program stands as perhaps the most significant mandate imposed to date to promote the use of biofuels. Overall, the RFS stands as the key driver in a transition to biofuels in the near term. By mandating annual consumption of biofuels, increasing to 36 bgy by 2022, the program has the potential to significantly alter the state of the U.S. liquid fuels sector. Fuel transitions in the transportation sector are the focus of this thesis. More specifically, the increasing consumption of biofuels in the transportation sector, as mandated by the RFS, is examined. With a well-developed, efficient, and expensive, petroleum-based infrastructure in place, many barriers must be overcome for biofuels to play a significant role in the transportation sector. Identifying and understanding the barriers to a biofuels transition is the objective of this thesis. Although fuel transitions may seem daunting and unfamiliar, the U.S. transportation sector has undergone numerous transitions in the past. Chapter 2 reviews major fuel transitions that have occurred in the U.S. liquid fuels sector over the last half century, including the phasing out of lead additives in gasoline, the transition from MTBE to ethanol as the predominant oxygenate additive in gasoline, and the recent introduction of ULSD. These historical transitions represent the uncertainty and diversity of fuel transition pathways, and illustrate the range of impacts that can occur across the fuel supply chain infrastructure. Many pertinent lessons can be derived from these historical transitions and used to identify and assess barriers facing the adoption of alternative fuels (i.e., biofuels) and to understand how such a transition might unfold. Computer models can also help to explore the implications of fuel transitions. In order to better understand the barriers associated with fuel transitions, and to identify options for overcoming these barriers, many recent research efforts have used sophisticated modeling techniques to analyze energy transitions. Chapter 3 reviews a number of these recent modeling efforts with a focus on understanding how these methodologies have been applied, or may be adapted, to analyzing a transition to biofuels. Four general categories of models are reviewed: system dynamics, complex adaptive systems, infrastructure optimization, and economic models. In chapter 4, scenarios created from a high-level model of the liquid fuels sector (the Liquid Fuels Transition model) are presented to explore potential pathways and barriers to a biofuels transition. The scenarios illustrate different pathways to meeting the requirements of the RFS mandate, and differ based on the overall demand of liquid fuels, how the biofuels mandate is met (i.e., the mix of biofuels), and the status of the ethanol blend limit in the motor gasoline sector. The scenarios are used to evaluate the infrastructure implications associated with a biofuels transition, and illustrate the uncertainty that exists in assessing such a transition. / text
7

Vers un design orienté de nouveaux catalyseurs zéolithiques sélectifs pour l'hydrocraquage / Towards a rational design of new zeolitic selective catalysts for hydrocracking

Francis, Jérémy 07 February 2012 (has links)
L’emploi de cristaux de zéolithe USY comme fonction acide et de phases sulfures de type NiMoS comme fonction hydro/deshydrogénante (H/DH) dispersée sur un liant de type alumine [NiMoS/(_-Al2O3 + USY)] permet l'obtention de catalyseurs bifonctionnels d’hydrocraquage très actifs mais dont la sélectivité en distillats moyens est relativement faible. Une des causes invoquées pour expliquer ces performances est la distance importante entre les sites H/DH et les sites acides qui entraine des réactions secondaires et la formation de produits légers. Dans ce travail, une phase H/DH additionnelle (nickel) a été insérée dans des zéolithes USY par différentes méthodes afin d’obtenir des catalyseurs contenant une phase sulfure localisée au plus proche des sites acides. L’utilisation de zéolithes imprégnées à sec et échangées avec du nickel dans des catalyseurs typiques d’hydrocraquage permet d’obtenir de meilleures activités et sélectivités en distillats moyens en hydroconversion du squalane (2,6,10,15,19,23- hexamethyltetracosane) que l’utilisation de zéolithe ne contenant pas de Ni. L’étude de la relation structure-réactivité des catalyseurs a permis de mettre en évidence que l’amélioration de la proximité entre fonction acide et fonction H/DH est bien à l’origine de l’amélioration des propriétés catalytiques. De plus, l’utilisation d’une zéolithe dans laquelle le nickel a été inséré à la synthèse conduit aussi à des résultats prometteurs. Ce travail ouvre ainsi une voie d’amélioration pour des catalyseurs d'hydrocraquage plus actifs et plus sélectifs en distillats moyens par insertion d’une phase H/DH additionnelle / Hydrocracking bifunctional catalysts can be obtained using USY zeolite crystals as an acid function and NiMoS metal sulfide phase as a hydro/dehydrogenating (H/DH) function dispersed on an alumina binder [NiMoS/(_-Al2O3 + USY)]. These catalysts are very active but have a moderate selectivity towards middle distillates. One of the suggested explanations is the large distance between the two different types of catalytic sites leading to secondary reactions and to the formation of light products. In this work, an additional H/DH phase (nickel) has been inserted in USY zeolites using various methods in order to obtain catalysts in which a sulfided phase is located in the vicinity of the acid sites. The use of impregnated or ion exchanged nickel containing zeolites in a typical hydrocracking catalyst leads to higher activities and middle distillates selectivities in the squalane (2,6,10,15,19,23-hexamethyltetracosane) hydroconversion reaction than the use of bare zeolites. According to the structure-reactivity relation of the catalysts, these enhancements are ascribed to an increased proximity between the H/DH function and the acid sites. Moreover, the use of a synthesized Ni-zeolite leads to promising results. The use of an additional H/DH phase as an optimization route for the production of more active and selective hydrocracking catalysts is then clearly supported by this work
8

Influ?ncia de tensoativos n?o i?nicos na destila??o molecular de petr?leo / Influence of nonionic surfactants in molecular distillation of petroleum

Lucena, Izabelly Larissa 12 July 2013 (has links)
Made available in DSpace on 2015-03-03T15:02:47Z (GMT). No. of bitstreams: 1 IzabellyLL_TESE.pdf: 7496453 bytes, checksum: d39fc896ff5d9d4982952835ef786c26 (MD5) Previous issue date: 2013-07-12 / The molecular distillation is show as an alternative for separation and purification of various kinds of materials. The process is a special case of evaporation at high vacuum, in the order from 0.001 to 0.0001 mmHg and therefore occurs at relatively lower temperatures, preserves the material to be purified. In Brazil, molecular distillation is very applied in the separation of petroleum fractions. However, most studies evaluated the temperature of the evaporator, condenser temperature and flow such variables of the molecular distillation oil. Then, to increase the degree of recovery of the fraction of the distillate obtained in the process of the molecular distillation was evaluated the use nonionic surfactants of the class of nonylphenol ethoxylate, molecules able to interact in the liquid-liquid and liquid-vapor interface various systems. In this context, the aim of this work was to verify the influence of commercial surfactant (Ultranex-18 an Ultranex-18-50) in the molecular distillation of a crude oil. The physicochemical characterization of the oil was realized and the petroleum shown an API gravity of 42?, a light oil. Initially, studied the molecular distillation without surfactant using star design experimental (2H ? ) evaluated two variables (evaporator temperature and condenser temperature) and answer variable was the percentage in distillate obtained in the process (D%). The best experimental condition to molecular distillation oil (38% distillate) was obtained at evaporator and condenser temperatures of 120 ?C and 10 ? C, respectively. Subsequently, to determine the range of surfactant concentration to be applied in the process, was determined the critical micellar concentration by the technique of scattering X-ray small angle (SAXS). The surfactants Ultranex-18 an Ultranex-18-50 shown the critical micelle concentration in the range of 10-2 mol/L in the hydrocarbons studied. Then, was applied in the study of distillation a concentration range from 0.01 to 0.15 mol/L of the surfactants (Ultranex- 18 and 50). The use of the nonionic surfactant increased the percentage of hydrocarbons in the range from 5 to 9 carbons in comparison to the process carried out without surfactant, and in some experimental conditions the fraction of light compounds in the distilled was over 700% compared to the conventional process. The study showed that increasing the degree of ethoxylation of Ultranex18 to Ultranex-50, the compounds in the range of C5 to C9 reduced the percentage in the distilled, since the increase of the hydrophilic part of the surfactant reduces its solubility in the oil. Finally, was obtained an increase in the degree of recovery of light hydrocarbons, comparing processes with and without surfactant, obtained an increase of 10% and 4% with Ultranex-18 and Ultranex-50, respectively. Thus, it is concluded that the Ultranex- 18 surfactant showed a higher capacity to distillation compared with Ultranex-50 and the application of surfactant on the molecular distillation from petroleum allowed for a greater recovery of light compounds in distillate / A destila??o molecular apresenta-se como uma alternativa para separa??o e purifica??o de diversos tipos de materias. O processo ? um caso especial de evapora??o a alto v?cuo, na ordem 0,001 a 0,0001 mmHg, e consequentemente, ocorre ? temperaturas relativamente mais baixas, preservando ao m?ximo o material a ser purificado. No Brasil, a destila??o molecular ? muito aplicada na separa??o de fra??es de petr?leo. No entanto, boa parte dos estudos relacionados a destila??o molecular de petr?leo avalia apenas as vari?veis do processo, tais como: a temperatura do evaporador, temperatura do condensador, vaz?o e etc. Dessa forma, com o prop?sito de favorecer a destila??o molecular, visando aumentar o grau de recupera??o da fra??o do destilado obtido no processo, avaliou-se a aplica??o de tensoativos n?o i?nicos da classe do nonilfenol etoxilado, uma vez que tais mol?culas apresentam a capacidade de interagir na interface l?quido-l?quido e l?quido-vapor de diversos sistemas. Portanto, o objetivo deste trabalho foi verificar a influ?ncia de tensoativo comerciais do tipo Ultranex-18 e Ultranex-50 na destila??o molecular de um petr?leo bruto. Nesse estudo, realizou-se a caracteriza??o f?sico-qu?mica do petr?leo a ser destilado, determinando-se que o mesmo apresentava um grau API de 42?, o que confere a amostra a ser destilada uma caracter?stica de fra??o leve. Na etapa do estudo das destila??es moleculares realizadas sem tensoativo, aplicou-se um planejamento estrela (2K ? ) com duas vari?veis (temperatura do evaporador e temperatura do condensador), tendo como resposta a porcentagem de destilado obtida no processo (%D). Verificou-se que a melhor condi??o experimental para a destila??o molecular do petr?leo estudado foi aplicando uma temperatura do evaporador de 120?C e do condensador de 10?C, obtendo-se uma porcentagem de destilado de 38 %. Posteriormente, para determinar uma faixa de concentra??o de tensoativo a ser aplicado no processo determinou-se a concentra??o micelar critica aplicando a t?cnica de espalhamento de raio-X de baixo ?ngulo (SAXS). Atrav?s da t?cnica, constatou-se que para os tensoativos da classe do nonilfenois etoxilados a concentra??o micelar cr?tica encontra-se na faixa de 10-2 mol/L para os hidrocarbonetos estudados. A partir dessa constata??o, aplicou-se no estudo das destila??es com tensoativo (Ultranex-18 e 50) uma faixa de concentra??o entre 0,01 a 0,15 mol/L. Nesta etapa, verificou-se que a presen?a do tensoativo n?o i?nico aumentou a destila??o de hidrocarbonetos na faixa de 5 a 9 carbonos em compara??o ao processo realizado sem tensoativo, e que em alguns casos a fra??o de compostos leves no destilado do processo foi superior a 700 % em rela??o ao processo convencional. O estudo mostrou que o aumento do grau de etoxila??o do Ultranex-18 para o Ultranex-50, reduziu a porcentagem de compostos destilados na faixa de C5 a C9, uma vez que o aumento da parte hidrof?lica do tensoativo reduz sua solubilidade no petr?leo. Finalmente, verificou-se que o aumento no grau de recupera??o de hidrocarbonetos leves, comparando os processos com o tensoativo e sem tensoativo, resultou em um aumento de 10 % para o processo empregando o Ultranex-18 e 4% para o Ultranex-50. Dessa forma, conclui-se que o Ultranex-18 apresentou maior capacidade de destila??o frente ao Ultranex-50 e que a aplica??o de tensoativo na destila??o molecular de petr?leo favoreceu o processo, j? que houve o aumento da concentra??o de compostos leves obtidos
9

Zařízení pro zahušťování odpadní vody z bioplynových stanic / Equipment for Thickening Waste Water from Biogas Plants

Vondra, Marek January 2017 (has links)
This dissertation thesis deals with the development of technology which could tackle two major issues related to biogas plants. These issues concern the insufficient use of waste heat from biogas combustion and its subsequent processing. It also concerns the use of the fermentation residues which are formed in large quantities and whose use is restricted by law. Based on a literary search of separation methods, a vacuum evaporator was selected as the most suitable technology. Its advantages include its simple construction, operational reliability and robustness, low costs of thickening medium pre-treatment, potential for a quick commercial application and, especially, the chance to use a low-potential waste heat. A primary purpose of this technological unit is the reduction in the volume of fermentation residues. Other benefits include the efficient use of waste heat from a biogas plant, which would otherwise be wasted. Evaporators with a low consumption of electrical energy (which is a main product of a biogas plant) seem to be the best option for applications in the biogas plants. Three of these technologies were subjected to a more thorough analysis, which included the development of computational models and their quantification for conditions in a sample biogas plant. A one-stage evaporator with a forced circulation (680 – 712 kWhth/m3, 25.9 – 30.5 kWhel/m3) was evaluated as the least suitable option in terms of energy demands. The energy intensity of a three-stage evaporator with a falling film (241 – 319 kWhth/m3, 12.0 – 23.6 kWhel/m3) and a nine-stage flash evaporator (236 – 268 kWhth/m3, 13.6 – 18.4 kWhel/m3) is significantly lower. A multi-stage flash evaporator (MSF) was then chosen for development and will form the central focus of this thesis. The reasons for the choice are as follows: the low requirements on the heat transfer surface, good operational experience in the field of desalination, its simple construction, modularity and evaporation outside the heat transfer surface. A thorough technical-economic evaluation was also performed on the integration of the evaporator into the biogas plant. The main part of the work included the experimental development of a MSF evaporator prototype. The main objective of this development was to achieve a stable flow rate of the thickening liquid digestate fraction and the continuous formation of the distillate. This was not an easy objective to achieve, especially due to the properties of the liquid digestate, which has a non-newtonian characteristic and increased density and viscosity compared to water. The tendency of the liquid digestate to form foam was also the subject of analysis. The development of the evaporator and first successful operational test are described in the thesis in detail. This required the use of an anti-foaming product. A fully-developed prototype of the MSF evaporator allowed us to achieve continuous operation with a distillate production, reaching from 5 to 10 kg/h at a liquid digestate flow rate of 0.4–0.5 m3/h. The main drawback of this technology is the pollution of the distillate with ammonia nitrogen, and it is for this reason that the basic procedures of its subsequent elimination was selected for further analysis.

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