Dissertations / Theses on the topic 'Natural gas/hydrogen mixtures'

The work presented in this thesis was undertaken as part of the safety work package of the NATURALHY project which was an integrated project funded by the European Commission (EC) within the sixth framework programme. The purpose of the NATURALHY project was to investigate the feasibility of using existing natural gas infrastructure to assist a transition to a hydrogen based economy by transporting hydrogen from its place of production to its place of use as a mixture of natural gas and hydrogen. The hydrogen can then be extracted from the mixture for use in fuel cells or the mixture used directly in conventional combustion devices. The research presented in this thesis focused on predicting the consequences of explosions and fires involving natural gas and hydrogen mixtures, using engineering type mathematical models typical of those used by the gas industry for risk assessment purposes. The first part of the thesis concentrated on modifying existing models that had been developed to predict confined vented and unconfined vapour cloud explosions involving natural gas. Three geometries were studied: a confined vented enclosure, an unconfined cubical region of congestion and an unconfined high aspect ratio region of congestion. The modifications made to the models were aimed at accounting for the different characteristics of a natural gas/hydrogen mixture compared to natural gas. Experimental data for the laminar burning velocity of methane/hydrogen mixtures was obtained within the safety work package. For practical reasons, this experimental work was carried at an elevated temperature. Predictions from kinetic modelling were employed to convert this information for use in models predicting explosions at ambient temperature. For confined vented explosions a model developed by Shell (SCOPE) was used and modified by adding new laminar burning velocity and Markstein number data relevant to the gas compositions studied. For vapour cloud explosions in a cubical region of congestion, two models were used. The first model was developed by Shell (CAM2), and was applied using the new laminar burning velocity and other composition specific properties. The second model was based on a model provided by GL Services and was modified by generalising the flame speed model so that any natural gas/hydrogen mixture could be simulated. For vapour cloud explosions in an unconfined high aspect ratio region of congestion, a model from GL Services was used. Modifications were made to the modelling of flame speed so that it could be applied to different fuel compositions, equivalence ratios and the initial flame speed entering the congested region. Predictions from the modified explosion models were compared with large scale experimental data obtained within the safety work package. Generally, (apart from where continuously accelerating flames were produced), satisfactory agreement was achieved. This demonstrated that the modified models could be used, in many cases, for risk assessment purposes for explosions involving natural gas/hydrogen mixtures. The second part of thesis concentrated on predicting the incident thermal radiation from high pressure jet fires and pipelines fires involving natural gas/hydrogen mixtures. The approach taken was to modify existing models, developed for natural gas. For jet fires three models were used. Fuel specific input parameters were derived and the predictions of flame length and incident radiation compared with large scale experimental data. For pipeline fires a model was developed using a multi-point source approach for the radiation emitted by the fire and a correlation for flame length. Again predictions were compared with large scale experimental data. For both types of fire, satisfactory predictions of the flame length and incident radiation were obtained for natural gas and mixtures of natural gas and hydrogen containing approximately 25% hydrogen.

The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.

The interactions between laminar premixed flames and counter-rotating vortex pairs in natural and synthetic gas mixtures have been computationally investigated through the use of Direct Numerical Simulations and parallel processing. Using a computational model for premixed combustion, laminar flames are simulated for single- and two-component fuel mixtures of methane, carbon monoxide, and hydrogen. These laminar flames are forced to interact with superimposed laminar vortex pairs, which mimic the effects of a pulsed, two-dimensional slot-injection. The premixed flames are parameterized by their unstretched laminar flame speed, heat release, and flame thickness. The simulated vortices are of a fixed size (relative to the flame thickness) and are parameterized, solely, by their rotational velocity (relative to the flame speed). Strain rate and surface curvature measurements are made along the stretched flame surfaces to study the effects of additive syngas species (CO and H2) on lean methane-air flames. For flames that share the same unstretched laminar flame speed, heat release, and flame thickness, it is observed that the effects of carbon monoxide on methane-air mixtures are essentially negigible while the effects of hydrogen are quite substantial. The dynamics of stretched CH4/Air and CH4/CO/Air flames are nearly identical to one another for interactions with both strong and weak vortices. However, the CH4/H2/Air flames demonstrate a remarkable tendency toward surface area growth. Over comparable interaction periods, the flame surface area produced during interactions with CH4/H2/Air flames was found to be more than double that of the pure CH4/Air flames. Despite several obvious differences, all of the interactions revealed the same basic phenomena, including vortex breakdown and flame pinch-off (i.e. pocket formation). In general, the strain rate and surface curvature magnitudes were found to be lower for the CH4/H2/Air flames, and comparable between CH4/Air and CH4/CO/Air flames. Rates of flame stretching are not explicitely determined, but are, instead, addressed through observation of their individual components. Two different models are used to determine local displacement speed values. A discrepancy between practical and theoretical definitions of the displacement speed is evident based on the instantaneous results for CH4/Air and CH4/H2/Air flames interacting with weak and strong vortices.

Thesis (M.S.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

The densities of three different natural gas mixtures (Case A, Case B, and Case C) were evaluated at pressures from 14 to 38 MPa (2000 to 5500 psia) and temperatures from 230 K to 350 K by using SonicWare? and NIST-14 software packages. The chosen pressures and temperatures were based on the phase diagrams for each composition and the probability of encountering such conditions in reservoir or pipeline environment. For each isotherm, the heaviest hydrocarbon was varied from 0 to 1 mole percent in increments of 0.001 (Dx=0.001) and the density calculated for each composition. After the densities were obtained, the partial derivatives of the densities with respect to composition, were calculated numerically at fixed pressure and temperature. The results and calculations suggest that it is very difficult to obtain the desired accuracy (+ 0.1 %) in densities when using a combination of composition measurements and equation of state calculations.

Highly accurate data for density measurements are required for engineering calculations as well for developing equations of state (EOS) for use in the custody transfer of natural gas through pipelines. The widely used present industry standard, the AGA8-DC92 EOS, was developed against a database of reference quality natural gas mixtures with compositions containing less than 0.2 mole percent of the heavier C6+ fraction. With the advances in technology in the late nineties, it is possible to produce gas from deep and ultra-deepwater of the Gulf of Mexico where the pressures and temperatures encountered are much higher. Produced gas mixtures have compositions containing higher percentages of the C6+ fraction. As AGA8-DC92 is a statistical fit equation developed for one set of conditions, time has come to evaluate its performance to assess whether it is still viable for gas custody transfer with a new set of conditions encountered. A highly accurate, high pressure and temperature, compact single sinker magnetic suspension densimeter has been used first to determine densities of pure component’s densities for which very reliable data are available. After validating its performance, the densities of four light natural gas mixtures, containing no C6+ fraction and two heavy gas mixtures containing more than 0.2 mole percent of the heavier C6+ fraction, were measured. The light mixtures were measured in the temperature range of 250 to 450 K and in the pressure range of 10 to 150 Mpa (1450 to 21,750 psi); the heavy mixtures were measured in the range of 270 to 340 K and in the pressure range of 3.45 to 34.45 MPa (500 to 5,000 psi). Out of those, the data of only two light natural gas mixtures have been presented in the dissertation. Data on two heavy mixtures have not been published due to reasons of confidentiality. Measured densities of light mixtures, not containing the C6+ fraction show less than expected relative deviations from the AGA8-DC92 EOS predictions except at low temperature. The deviation with the recently developed GERG02 EOS was more pronounced. A force transmission error analysis and uncertainty analysis was carried out. The total uncertainty was calculated to be 0.105 %. The data measured as a part of this research should be used as reference quality data either to modify the parameters of AGA8-DC92 EOS or develop a more reliable equation of state with wider ranges of pressure and temperature.

This research investigates the effect of feed composition on the separation performance of pure polyethersulfone (PES) and different types of PES based mixed matrix membranes (MMMs) in order to develop high performing membranes for CO2/CH4 separation. MMMs were prepared by solvent evaporation method using PES as the polymer matrix with SAPO-34 particles as fillers, and 2-hydroxy 5-methyl aniline (HMA) as the low molecular weight additive. Four types of membranes were used throughout the study, namely pure PES membrane, PES/HMA (4, 10%w/w) membrane, PES/SAPO-34 (20%w/w) MMM, PES/SAPO-34 (20%w/w)/HMA (4, 10%w/w) MMM. The effect of CO2 composition on the performance of the membranes was investigated in detail with a wide feed composition range changing between 0 and 100%. In addition to separating CO2/CH4 binary gas mixtures, the separation performances of these membranes were determined by measuring single gas permeabilities at 35º
C, with a feed pressure of 3 bar. Moreover, the membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analyzer (TGA). The separation selectivities of all types of membranes generally observed to be independent of feed composition. The composition independency of these membranes eliminates the need of investigating at which feed gas composition the prepared membranes are best performing for practical applications. PES/SAPO-34/HMA MMMs with HMA loading of 10% and SAPO-34 loading of 20% demonstrated the highest separation selectivity of about 40, and the ideal selectivity of 44, among the used membranes.

As reserves of conventional crude oil are depleted, there is a growing need to develop unconventional oils such as heavy oil and bitumen from oil sands. In terms of recoverable oil, Canadian oil sands are considered to be the second largest oil reserves in the world. However, the upgrading of bitumen from oil sands to synthetic crude oil (SCO) requires nearly ten times more hydrogen (H₂) than the conventional crude oils. The current H₂ demand for oil sands operations is met mostly by steam reforming of natural gas. With the future expansion of oil sands operations, the demand of H₂ for oil sand operations is likely to quadruple in the next decade. As natural gas reforming involves significant carbon dioxide (CO₂) emissions, this sector is likely to be one of the largest emitters of CO₂ in Canada.

In the current H₂ plants, CO₂ emissions originate from two sources, the combustion flue gases from the steam reformer furnace and the off-gas from the process (steam reforming and water-gas shift) reactions. The objective of this study is to develop a process that captures CO₂ at minimum energy penalty in typical H₂ plants.

The approach is to look at the best operating conditions when considering the H₂ and steam production, CO₂ production and external fuel requirements. The simulation in this study incorporates the kinetics of the steam methane reforming (SMR) and the water gas shift (WGS) reactions. It also includes the integration of CO₂ capture technologies to typical H₂ plants using pressure swing adsorption (PSA) to purify the H₂ product. These typical H₂ plants are the world standard of producing H₂ and are then considered as the base case for this study. The base case is modified to account for the implementation of CO₂ capture technologies. Two capture schemes are tested in this study. The first process scheme is the integration of a monoethanolamine (MEA) CO₂ scrubbing process. The other scheme is the introduction of a cardo polyimide hollow fibre membrane capture process. Both schemes are designed to capture 80% of the CO₂ from the H₂ process at a purity of 98%.

The simulation results show that the H₂ plant with the integration of CO₂ capture has to be operated at the lowest steam to carbon (S/C) ratio, highest inlet temperature of the SMR and lowest inlet temperatures for the WGS converters to attain lowest energy penalty. H₂ plant with membrane separation technology requires higher electricity requirement. However, it produces better quality of steam than the H₂ plant with MEA-CO₂ capture process which is used to supply the electricity requirement of the process. Fuel (highvale coal) is burned to supply the additional electricity requirement. The membrane based H₂ plant requires higher additional electricity requirement for most of the operating conditions tested. However, it requires comparable energy penalty than the H₂ plant with MEA-CO₂ capture process when operated at the lowest energy operating conditions at 80% CO₂ recovery.

This thesis also investigates the sensitivity of the energy penalty as function of the percent CO₂ recovery. The break-even point is determined at a certain amount of CO₂ recovery where the amount of energy produced is equal to the amount of energy required. This point, where no additional energy is required, is approximately 73% CO₂ recovery for the MEA based capture plant and 57% CO₂ recovery for the membrane based capture plant.

The amount of CO₂ emissions at various CO₂ recoveries using the best operating conditions is also presented. The results show that MEA plant has comparable CO₂ emissions to that of the membrane plant at 80% CO₂ recovery. MEA plant is more attractive than membrane plant at lower CO₂ recoveries.

In underground oil reservoirs, Hydrogen sulfide is usually found coexisting with the oil due to bacteria reduction over a long period of time. The amount of H2S in the oil varies from place to place around the globe. When the oil extraction process begins, the presence of Hydrogen sulfide becomes noticeable as drilling tools, piping and other equipment suffer from sulfide stress cracking, electrochemical corrosion and corrosion fatigue. For this reason, the oil industry invests millions of dollars per year trying to find better ways to reduce the amount of H2S in oil. An important part of the current investigations deals with brine (sea water)/oil mixtures. The reasons are two-fold: 1) one way of extracting the petroleum from the reservoir is by injecting brine into it and since it has a higher density than oil, the latter will be ejected up to the surface. Taking into account the complex fluid flow occurring within the reservoir it is easy to understand that some brine will also be present as part of the ejected fluid; 2) brine is already present in the reservoir, so independent of the extraction method used, there will be a brine/oil mixture in the ejected flow. When brine and oil have absorbed H2S under pressure in the reservoir and then suffer a decompression during the extraction process, a certain amount of H2S is released from the liquid phase. In order to have a better prediction of how much Hydrogen sulfide can be liberated a good understanding of H2S absorption by these liquids is necessary. The amount of gas a solvent absorbs is a function of pressure, original gas concentration and temperature as described by Henry's Law. The purpose of this thesis is to experimentally analyze how much of the corrosive gas is absorbed into different brine/oil mixtures, and brine and oil, separately. In order to find sufficient data for a thorough analysis, different reservoir simulation scenarios were created. The liquids were mixed from pure brine to pure oil, resulting in 33% and 66% water cuts. Data were obtained at 2 pressures of 20atm and 70atm at room temperature. H2S concentration was also a variable, changing the original gas concentration through different values: 50, 100, and 300ppm. These experiments were conducted in an autoclave system and will better explain the hydrostatic process that occurs inside the reservoir. It was found that throughout all the water cuts, the role that total pressure plays in the absorption phenomena is of less importance as the original H2S concentration is increased. In the same manner it was observed that the highest mass-absorption ratios are always found between 50 and 100ppm and the lowest at 300ppm, this is observed for all water cuts and total pressures. Another important finding was that the ability to absorb the corrosive gas decreases as the original H2S concentration increases and this proves to be true for all water cuts and system pressures. After conducting these different reservoir scenarios, tests were conducted to simulate 300m of the horizontal section of the pipe that connects the head of the well with the platform. This was done with a high pressure 300-meter long loop. It was found that the corrosive gas is absorbed at a higher rate when there is a flow, opposite to a hydrostatic case. Henry's Law constant was identified for each water cut and each pressure, however, the test procedure could not be validated since the gas being studied was not in its pure form. Understanding the absorption phenomena of Hydrogen sulfide in different water cuts will definitely be of great help to the oil industry to make better forecasts of H2S concentrations being ejected from each well.
M.S.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering MSAE

Doutoramento em Engenharia Química
Among various methods for the separation of hydrogen containing mixtures, membrane technology has received special attention due to its simplicity of operation, moderate energy consumption, cost effectiveness, it is environmentally friendly and can be easily coupled with other separation methods. In particular, inorganic membranes exhibit relevant advantages such as high thermal, chemical and mechanical stabilities, minor plasticization and better control of pore size distribution. They can be divided into five main families: metallic and ceramic proton conducting membranes (dense phases), and silica, zeolite and carbon molecular sieve membranes (porous materials). With more than 200 framework types, zeolites possess uniform molecular pore dimensions and unique properties for catalytic, ion exchange, adsorption and membrane applications. This thesis is essentially devoted to zeolite (titanosilicate) membranes for hydrogen and light gases separation. Titanosilicates offer important benefits over the remaining zeolites: they are usually synthesized without organic templates, can be prepared under moderate pH conditions, exhibit novel possibilities of isomorphous framework substitution, and generally offer strong alkalinity. The main objectives of this dissertation were: (i) synthesis and characterization of titanosilicate membranes. The materials structure and morphology were examined by X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS); the dynamic characterization of membranes was accomplished by permeation assays with pure gases; (ii) deep analysis of experimental results, with the objective to disclose the mass transport mechanisms that prevail in the membrane; (iii) accurate modeling of permeation data using theoretically sound approaches like the generalized Maxwell-Stefan (MS) formalism; (iv) development of new MS thermodynamic factors to represent the surface diffusion of pure and multicomponent gases through microporous membranes. Here, several important (though less studied) isotherms were tested, the influence of the solid loading upon surface diffusivity was deeply evaluated, and the predictive ability of the whole model was validated. The hydrothermal synthesis and characterization of AM-2 and AM-3 powder and supported membranes have been performed. Altogether, ca. thirty and more than one hundred syntheses of AM-2 and AM-3 powder, respectively, have been accomplished, and eight AM-2 and twenty AM-3 membranes have been prepared on tubular -alumina and stainless-steel supports by seeding and secondary growth. All powders were characterized by XRD and/or SEM, and three AM-2 and seven AM-3 membranes were dynamically tested. The permeation of pure gases at programmed temperature and fixed transmembrane pressure drop ( P) was carried out in order to evaluate the membranes quality and identify the governing transport mechanisms (e.g. viscous flow, Knudsen regime, surface diffusion, activated gaseous diffusion). Additionally, more than one hundred permeance measurements were conducted at various temperatures and pressures using different gases (H2, He, N2, O2 and CO2). The best AM-3 membrane was studied in detail at P=0.5, 1.0 and 1.5 bar, at fixed and programmed temperatures between 304 and 394 K, using H2, He, N2, O2 and CO2. The results provided selectivities towards hydrogen up to 3.5, and disclosed in all cases an activated behavior typical of surface diffusion, a small contribution of viscous flow due to macro-defects, and a minor contribution of Knudsen mechanism due to meso-defects. The gas permeation was accurately modeled using Maxwell-Stefan theory, achieving an average deviation of only 3.42 % for all molecules. The rigorous MS thermodynamic factors of various relevant isotherms – Toth, Dubinin-Astakhov (DA) and Dubinin-Radushkevich (DR) – were derived in this work for the first time, with the objective to model the permeation of pure and mixed gases through zeolite membranes. The DA and DR isotherms received special attention, taking into account they are often adopted to represent the adsorption equilibrium of most industrial adsorbents that possess a welldeveloped porous structure, especially of carbonaceous origin. The MS factors for DA and DR isotherms were validated using equilibrium and flux data for methane/silicalite-1, ethane/silicalite-1 and (methane,ethane)/ silicalite-1 systems according to the following procedure: (i) the unary isotherms were fitted to the corresponding data, while their binary expressions were predicted from the previous ones; (ii) the influence of surface loading upon methane and ethane diffusivities was carefully assessed; (iii) the MS diffusion parameters of each gas were obtained from unary permeation data; (iv) the MS counter-sorption diffusivities were then predicted using the Vignes correlation; (v) the separation of methane/ethane mixtures using the silicalite-1 membrane was totally predicted using the new MS thermodynamic factors combined with the binary isotherms. The results demonstrated the validity of this approach, particularly if DA isotherm is selected. Besides the main focus of this PhD on membranes, ion exchange experiments and modeling were also included. The removal of ionic contaminants (Cd2+ and Hg2+) from aqueous solutions was studied using synthesized stannosilicate AV- 6 and titanosilicate ETS-4. In the case of the Cd2+/K+/AV-6 system, the kinetic removal was modeled with Maxwell-Stefan (MS) and Nernst-Plank (NP) equations, while equilibrium was modeled with mass action law and activity coefficients in both solution (Debye-Hu ckel and Pitzer models) and exchanger (Wilson model) phases. The experimental data proved the ion exchange ability of AV-6 to sorb cadmium(II), and excellent results were achieved for the equilibrium isotherm (deviations around 6.6 %) and kinetic modeling (MS, 3.74 %; NP, 3.71 %). It was shown that the solid phase is clearly non-ideal. The investigation of the ternary system (Cd2+,Hg2+)/Na+/ETS-4 confirmed the large capacity of ETS-4 (5.44 meq g-1) and its selectivity towards both toxic metals, particularly Cd2+. However, the trends of the ion exchange kinetics were very distinct, because the internal diffusivity of cadmium(II) is higher than that of mercury(II). These results are in accordance with the effective ionic radius of both species, namely, 102 pm for Hg2+ and only 95 for Cd2+.
Entre diversos métodos de separação de misturas gasosas contendo hidrogénio, os processos membranares têm recebido uma atenção especial devido à sua simplicidade de operação, consumo moderado de energia, boa relação custo-eficiência, vantagens para o meio ambiente, e podem ser facilmente combinados com outros métodos de separação. Em particular, as membranas inorgânicas exibem vantagens relevantes, podendo citar-se as estabilidades térmica, química e mecânica elevadas, plasticização reduzida e um melhor controlo da distribuição do tamanho dos poros. Estas podem ser divididas em cinco famílias principais: metálicas e cerâmicas densas (membranas densas); e de sílica, zeolíticas e de peneiro molecular de carbono (membranas porosas). Com mais de 200 estruturas, os zeólitos possuem poros uniformes de dimensão molecular e propriedades únicas para aplicações catalíticas, de permuta iónica, de adsorção e membranares. Esta dissertação dedica-se fundamentalmente a membranas zeolíticas (titanossilicatos) para a separação de hidrogénio e gases leves. Os titanossilicatos oferecem vantagens importantes em relação aos restantes zeólitos: são geralmente sintetizados sem agentes orgânicos estruturantes e sob condições moderadas de pH, exibem novas possibilidades de substituição isomórfica da matriz, e oferecem geralmente uma forte alcalinidade. Os objetivos principais desta dissertação foram: (i) síntese e caracterização de membranas de titanossilicatos. A estrutura dos materiais e a sua morfologia foram examinadas por difração de raios-X (DRX) e microscopia eletrónica de varrimento acoplada a espectroscopia de energia dispersiva de raios-X (SEM/EDS). A caracterização dinâmica das membranas foi efetuada com ensaios de permeação utilizando gases puros; (ii) análise aprofundada dos resultados experimentais, com o objetivo de compreender os mecanismos de transporte de massa que prevalecem na membrana; (iii) modelação rigorosa dos dados de permeação, seguindo abordagens como o formalismo de Maxwell-Stefan (MS); (iv) derivação de novos fatores termodinâmicos de MS para representar a difusão superficial de gases puros e misturas através de membranas microporosas. Foram investigadas isotérmicas importantes, (mesmo que pouco utilizadas na literatura), a dependência da difusividade superficial com a concentração no sólido, e a capacidade preditiva de todo o modelo. A síntese hidrotérmica e a caracterização dos titanossilicatos AM-2 e AM-3 foram efetuadas com o material na forma de pó e suportado em membranas. Realizaram-se cerca de trinta sínteses de cristais de AM-2 e mais de uma centena de AM-3, para além de oito membranas de AM-2 e vinte membranas de AM-3 suportadas em tubos de -alumina e de aço inoxidável, recorrendo ao método do crescimento secundário. Todos os cristais obtidos foram caracterizados por DRX e/ou S SEM, e testaram-se dinamicamente três SEM membranas de AM-2 e sete membranas de AM-3. A permeação de gases puros a temperatura programada e a pressão transmembranar fixa ( P) foi realizada com o objetivo de avaliar a qualidade das membranas e identificar os mecanismos de transporte envolvidos (fluxo viscoso, regime de Knudsen, difusão superficial, difusão gasosa ativada). Foram concluídas mais de uma centena de medições de permeação a várias temperaturas e pressões usando gases diferentes (H2, He, N2, O2 e CO2). A melhor membrana de AM-3 foi estudada em detalhe para P = 0,5, 1,0 e 1,5 bar, a temperatura fixa e a temperatura programada entre 304 e 394 K, usando H2, He, N2, O2 e CO2. Os resultados obtidos evidenciaram seletividades para o hidrogénio até 3,5, comportamento ativado típico de difusão superficial em todos os casos, uma pequena contribuição de fluxo viscoso devido a macrodefeitos e uma contribuição residual do mecanismo de Knudsen atribuível a meso-defeitos. A permeação gasosa foi modelada rigorosamente usando o formalismo de Maxwell-Stefan, apresentando um desvio médio de apenas 3,42% para todas as moléculas simultaneamente. Os fatores termodinâmicos de MS para as isotérmicas de Toth, Dubinin- Astakhov (DA) e Dubinin-Radushkevich (DR) foram derivados neste trabalho, com o objetivo de modelar a permeação de gases puros e misturas através de membranas zeolíticas. As isotérmicas de DA e DR receberam uma atenção especial, tendo em conta que são frequentemente adotadas para representar o equilíbrio de adsorção da maioria dos adsorventes industriais que têm uma estrutura porosa bem definida, especialmente com origem carbonácea. Os fatores de Maxwell-Stefan para DA e DR foram validados com dados experimentais de equilíbrio e de fluxo dos sistemas metano/silicalite-1, etano/silicalite-1 e (metano,etano)/silicalite-1 de acordo com o seguinte procedimento: (i) os parâmetros das isotérmicas dos gases puros foram ajustados aos dados correspondentes, e as isotérmicas binárias foram previstas a partir das anteriores; (ii) a influência da concentração do sólido sobre as difusividades superficiais do metano e do etano foi analisada cuidadosamente; (iii) os parâmetros de difusão de MS de cada gás foram obtidos a partir dos dados de permeação mono-componente; (iv) os coeficientes de difusão multicomponente de MS foram estimados com a correlação de Vignes; (v) a separação de misturas metano/etano usando uma membrana de silicalite-1 foi totalmente prevista com recurso aos novos fatores termodinâmicos de MS combinados com as isotérmicas binárias. Os resultados comprovaram a validade desta abordagem, especialmente no caso da isotérmica de DA. Apesar de a área principal deste doutoramento estar relacionada com membranas, foram incluídas experiências de permuta iónica e sua modelação. A remoção de contaminantes tóxicos (Cd2+ e Hg2+) de soluções aquosas foi estudada usando o estanhossilicato AV-6 e o titanossilicato ETS-4. No caso do sistema Cd2+/K+/AV-6, a cinética de remoção foi modelada com as equações de Maxwell-Stefan (MS) e de Nernst-Plank (NP), enquanto o equilíbrio foi modelado com a lei da ação das massas expressa em atividades, usando-se coeficientes de atividade na solução (modelos de Debye-Hückel e Pitzer) e no permutador (modelo de Wilson). Os dados experimentais evidenciaram a capacidade de permuta do AV-6 para sorver cádmio(II) e obtiveram-se resultados excelentes para a isotérmica de equilíbrio (desvios de 6,6 %) e para a modelação cinética (MS = 3,74 %; NP = 3,71%). Ficou ainda demonstrado que a fase sólida é claramente não-ideal. A investigação do sistema ternário (Cd2+,Hg2+)/Na+/ETS-4 confirmou a elevada capacidade do ETS-4 (5,44 meq g-1) e a sua seletividade para os dois metais tóxicos, particularmente para o Cd2+. Contudo, o comportamento das cinéticas de permuta iónica foi muito distinto, uma vez que a difusividade interna do cádmio(II) é superior à do mercúrio(II). Estes resultados estão de acordo com o raio iónico efetivo de ambas as espécies, ou seja, 102 pm para o Hg2+ e apenas 95 pm para o Cd2+.

The first part of this essay aims at investigating the already available and promising technologies for the biogas and bio-hydrogen production from anaerobic digestion of different organic substrates. One strives to show all the peculiarities of this complicate process, such as continuity, number of stages, moisture, biomass preservation and rate of feeding. The main outcome of this part is the awareness of the huge amount of reactor configurations, each of which suitable for a few types of substrate and circumstance. Among the most remarkable results, one may consider first of all the wet continuous stirred tank reactors (CSTR), right to face the high waste production rate in urbanised and industrialised areas. Then, there is the up-flow anaerobic sludge blanket reactor (UASB), aimed at the biomass preservation in case of highly heterogeneous feedstock, which can also be treated in a wise co-digestion scheme. On the other hand, smaller and scattered rural realities can be served by either wet low-rate digesters for homogeneous agricultural by-products (e.g. fixed-dome) or the cheap dry batch reactors for lignocellulose waste and energy crops (e.g. hybrid batch-UASB). The biological and technical aspects raised during the first chapters are later supported with bibliographic research on the important and multifarious large-scale applications the products of the anaerobic digestion may have. After the upgrading techniques, particular care was devoted to their importance as biofuels, highlighting a further and more flexible solution consisting in the reforming to syngas. Then, one shows the electricity generation and the associated heat conversion, stressing on the high potential of fuel cells (FC) as electricity converters. Last but not least, both the use as vehicle fuel and the injection into the gas pipes are considered as promising applications. The consideration of the still important issues of the bio-hydrogen management (e.g. storage and delivery) may lead to the conclusion that it would be far more challenging to implement than bio-methane, which can potentially “inherit” the assets of the similar fossil natural gas. Thanks to the gathered knowledge, one devotes a chapter to the energetic and financial study of a hybrid power system supplied by biogas and made of different pieces of equipment (natural gas thermocatalitic unit, molten carbonate fuel cell and combined-cycle gas turbine structure). A parallel analysis on a bio-methane-fed CCGT system is carried out in order to compare the two solutions. Both studies show that the apparent inconvenience of the hybrid system actually emphasises the importance of extending the computations to a broader reality, i.e. the upstream processes for the biofuel production and the environmental/social drawbacks due to fossil-derived emissions. Thanks to this “boundary widening”, one can realise the hidden benefits of the hybrid over the CCGT system.

The inordinate reliance of the United States on the automobile for transportation causes a number of problems for the nation. Finite supplies of petroleum imported from volatile parts of the world place the economy at risk from price spikes and eventual depletion. Pollution from motor vehicle exhaust has public health and environmental consequences. Many politicians, automotive interest groups, and others advocate for the use of alternative fuels to replace fossil fuels. This paper investigates the advantages and disadvantages of the following: Natural Gas, Ethanol, Biodiesel, Hydrogen Fuel Cells, and Hybrid Gasoline Electric Systems. The paper concludes with a discussion of the problems associated with the automobile that will not be addressed through a movement towards alternative fuels: urban sprawl, transportation equity, environmental degradation, and public health.
Master of Urban and Regional Planning

Hydrogen fuel cell systems have many characteristics which are attractive for the heavyduty transport industry, including complementarity with electric vehicles and a cross-benefit from developments in batteries and electric drivetrains. Fuel cells may find their niche in the electrification of heavy-duty drivetrains, where zero emissions are desirable and where duty cycle or payload requirements exceed the capabilities of battery-only vehicles. Three hydrogen fuel cell buses (HFCBs) were trialled in Perth from 2004 to 2007. Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) models were developed based on primary data. The LCA and LCC determine the overall environmental, energetic and economic performance of each technology by enumerating all phases of the complete transportation system including the fuel infrastructure, bus manufacturing, operation, and end-of-life disposal. LCA’s of the existing diesel and natural gas transportation systems were developed in parallel. In 2013 Transperth introduced a diesel-electric hybrid bus, which was incorporated in the study. International state-of-the-art HFCB data was also collected and modelled to determine the performance of a next-generation fleet in Perth. HFCB and Diesel-electric Hybrid technologies are compared to the baseline performance of the current Diesel bus fleet operating in Perth. The HFCB is modelled for several Australian hydrogen production pathways, and finds that electrolysis using grid electricity would increase emissions dramatically across all impact categories, while hydrogen from natural gas reforming provides a modest improvement. Electrolysis from wind dramatically reduces total emissions. The diesel-electric hybrid achieves a significant emissions reduction. However, the LCC finds that both the diesel-electric hybrid and the HFCB are far from costcompetitive with Diesel on a Total Cost of Ownership basis. An uncertainty analysis quantifies the potential LCA error, and several sensitivity analyses are used to understand the key factors that dominate the LCA and LCC outcomes, the breakeven points, and areas for further research.

Orientador: Carlos Alberto Bandeira Guimarães
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Neste trabalho se apresentam argumentos econômicos e de meio ambiente para o uso de GNC em ônibus de transporte público, na forma de gás-diesel. Assim, os objetivos deste trabalho são: Analisar e comparar a experiência real do uso de gás-diesel em outros países e também no Brasil, para oferecer alternativa de combustível Gás Natural Comprimido (GNC) para as empresas de transporte urbano. Fundamentar as vantagens econômicas de reduzir o consumo de combustível diesel em ônibus a gás-diesel, usando como combustível uma mistura de diesel e GNC. Fazer os cálculos de demanda crescente de GNC com a substituição de combustível diesel por GNC nos ônibus urbanos
Abstract: This work presents strong economical and enviromental arguments in favour of the use of CNG (Compress Natural Gas) in the passengers's public transport (buses). The main object of this work is to analyse and compare the real experience in the use of gas/diesel fuel in Brazil and in other countries in an attempt to give an alternative gas fuel system in the public transport. Also it establishes and explains the economical advantage in reducing the consume of diesel fuel in the gas/diesel buses, by the use of a diesel/CNG mixture. Finally, the calculations made show the increasing demand of CNG with the substitution of diesel fuel by CNG in the buses of the public transport
Mestrado
Geotecnia
Mestre em Engenharia Civil

The goal is of this project was to identify principles to guide the development of high performance dense film membranes for natural gas sweetening using hydrogen sulfide and carbon dioxide gas mixtures as models under aggressive sour gas feed conditions. To achieve this goal, three objectives were developed to guide this research. The first objective was to study the performance of cellulose acetate (CA) and an advanced crosslinkable polyimide (PDMC) dense film membrane for H₂S separation from natural gas. The second objective was to engineer those polymers to produce membrane materials with superior performance as measured by efficiency, productivity, and plasticization resistance, and the third objective was to determine the separation performance of these engineered membrane materials under more aggressive, realistic natural gas feeds, and to perform a detailed transport analysis of the factors that impact their performance. Work on the first objective showed that in neat CA, penetrant transport is controlled by both the solubility and mobility selectivity, with the former being more dominant, leading to a high overall CO₂/CH₄ (33) and H₂S/CH₄ (35) ideal selectivities. However, in uncrosslinked PDMC, H₂S/CH₄ selectivity favored sorption only, whereas CO₂/CH₄ selectivity favored both mobility and sorption selectivity, leading to a high CO₂/CH₄ (37) but low H₂S/CH₄ (12) ideal selectivities. However, the latter polymer showed more plasticization resistance for CO₂. In the second objective, both materials were engineered. A new technique referred to as “GCV-Modification” was introduced in which cellulose acetate was grafted using vinyltrimethoxysilane (VTMS), then hydrolyzed and condensed to form a polymer network. PDMC was also covalently crosslinked to enhance its performance. GCV-Modified CA showed significant performance improvements for H₂S and CO₂ removal; the permeability of CO₂ and H₂S were found to be 139 and 165 Barrer, respectively, which represented a 30X and 34X increase compared to the pristine CA polymer. The H₂S/CH₄ and CO₂/CH₄ ideal selectivities were found to be 39 and 33, respectively. Crosslinked PDMC showed a higher CO₂/CH₄ selectivity of 38 with a better plasticization resistance for CO₂ and H₂S. In the third objective, these materials were tested under aggressive ternary mixtures of H₂S/CO₂/CH₄ with both vacuum and nonvacuum downstream. Even under aggressive feed conditions, GCV-Modified CA showed better performance vs. PDMC, and it remained were fairly stable, making it a potential candidate for aggressive sour gas separations, not only because of its significantly higher productivity, which will help decrease the surface area needed for separation, thereby reducing operating costs, but also because of the lower cost of the raw material GCV-Modified CA compared to PDMC.

The exigent need to address climate change and its adverse effects is felt all around the world. As pioneers in tackling carbon emissions, the European Union continue to be head and shoulders above other continents by implementing policies and keeping a tab on its carbon dependence and emissions. However, being one of the largest importers of Natural Gas in the world, the EU remains dependent on a fossil fuel to meet its demands.  The aim of the research is to investigate the barriers and constraints in the EU policies and framework that affects the natural gas decarbonization and to investigate the levelized cost of hydrogen production (LCOH) that would be used to decarbonize the natural gas sector. Thus a comprehensive study, based on existing academic and scientific literature, EU policies, framework and regulations pertinent to Natural gas and a techno economic analysis of possible substitution of natural gas with Hydrogen, is performed. The motivation behind choosing hydrogen is based on various research studies that indicate the importance and ability to replace to natural gas. In addition, Portugal provides a great environment for cheap green hydrogen production and thus chosen as the main region of evaluation.  The study evaluates the current framework based on a SWOT ((Strength, Weakness, and Opportunities & Weakness) analysis, which includes a PESTEL (Political, Economic, Social, Technological, Environmental & Legal) macroeconomic factor assessment and an expert elicitation. The levelized cost of hydrogen is calculated for blue (SMR - Steam Methane Reforming with natural gas as the feedstock) and green hydrogen (Electrolyzer with electricity from grid, solar and wind sources). The costs were specific to Portuguese conditions and for the years 2020, 2030 and 2050 based on availability of data and the alignment with the National Energy and Climate Plan (NECP) and the climate action framework 2050. The sizes of Electrolyzers are based on the current Market capacities while SMR is capped at 300MW. The thesis only considers production of hydrogen. Transmission, distribution and storage of hydrogen are beyond the scope of the analysis.  Results show that the barriers are mainly related to costs competitiveness, amendments in rules/regulations, provisions of incentives, and constraints in the creation of market demand for low carbon gases. Ensuring energy security and supply while being economically feasible demands immediate amendments to the regulations and policies such as incentivizing supply, creating a demand for low carbon gases and taxation on carbon.  Considering the LCOH, the cheapest production costs continue to be dominated by blue hydrogen (1.33 € per kg of H2) in comparison to green hydrogen (4.27 and 3.68 € per kg of H2) from grid electricity and solar power respectively. The sensitivity analysis shows the importance of investments costs and the efficiency in case of electrolyzers and the carbon tax in the case of SMR. With improvements in electrolyzer technologies and increased carbon tax, the uptake of green hydrogen would be easier, ensuring a fair yet competitive gas market.
Det starka behovet av att ta itu med klimatförändringarna och deras negativa effekter är omfattande världen över. Den europeiska unionen utgör en pionjär när det gäller att såväl hantera sina koldioxidberoende och utsläpp som att implementera reglerande miljöpolitik, och framstår därmed som överlägsen andra stater och organisationer i detta hänseende. Unionen är emellertid fortfarande mycket beroende av fossilt bränsle för att uppfylla sina energibehov, och kvarstår därför som en av världens största importörer av naturgas.  Syftet med denna forskningsavhandling är att undersöka befintliga hinder och restriktioner i EU: s politiska ramverk som medför konsekvenser avkolningen av naturgas, samt att undersöka de utjämnande kostnaderna för väteproduktion (LCOH) som kan användas för att avkolna naturgassektorn. Därmed utförs en omfattande studie baserad på befintlig akademisk och vetenskaplig litteratur, EU: s politiska ramverk och stadgar som är relevanta för naturgasindustrin. Dessutom genomförs en teknisk-ekonomisk analys av eventuella ersättningar av naturgas med väte. Valet av väte som forskningsobjekt motiveras olika forskningsstudier som indikerar vikten och förmågan att ersätta till naturgas. Till sist berör studien Portugal. som tillhandahåller en lämplig miljö för billig och grön vätgasproduktion. Av denna anledning är Portugal utvalt som den viktigaste utvärderingsregionen.  Studien utvärderar det nuvarande ramverket baserat på en SWOT-analys ((Strength, Weakness, and Opportunities & Weakness), som inkluderar en PESTEL (Political, Economical, Social, Technological, Environmental och Legal) makroekonomisk faktoranalys och elicitering. Den utjömnade vätekostnaden beräknades i blått (SMR - Ångmetanreformering med naturgas som råvara) och grönt väte (elektrolyser med el från elnät, sol och vindkällor). Kostnaderna var specifika för de portugisiska förhållandena under åren 2020, 2030 och 2050 baserat på tillgänglighet av data samt anpassningen till den nationella energi- och klimatplanen (NECP) och klimatåtgärdsramen 2050. Storleken på elektrolyserar baseras på den nuvarande marknadskapaciteten medan SMR är begränsad till 300 MW. Avhandlingen tar endast hänsyn till produktionen av vätgas. Transmission, distribution och lagring av väte ligger utanför analysens räckvidd.  Resultaten visar att hindren är främst relaterade till kostnadskonkurrens, förändringar i stadgar och bestämmelser, incitament och begränsningar i formerandet av efterfrågan på koldioxidsnåla gaser på marknaden. Att säkerställa energiförsörjning och tillgång på ett ekonomiskt hållbart sätt kräver omedelbara ändringar av reglerna och politiken, såsom att stimulera utbudet, att skapa en efterfrågan på koldioxidsnåla gaser och genom att beskatta kol.  När det gäller LCOH dominerar blåväte beträffande produktionskostnaderna (1,33 € per kg H2) jämfört med grönt väte (4,27 respektive 3,68 € per kg H2) från elnät respektive solenergi. Osäkerhetsanalysen visar vikten av investeringskostnader och effektiviteten vid elektrolysörer och koldioxidskatten för SMR. Med förbättringar av elektrolys-tekniken och ökad koldioxidskatt skulle upptagningen av grön vätgas vara enklare och säkerställa en rättvis men konkurrenskraftig gasmarknad.

Este trabalho tem como objetivo apresentar, através da modelagem de uma planta gásquímica e da identificação das tecnologias disponíveis, a versatilidade do uso do gás natural como insumo para a indústria química, visando à produção de metanol, amônia e hidrogênio, a partir da fração metano, bem como na indústria petroquímica a obtenção do eteno através da fração etano. Baseado nas pesquisas de mercado, determinou-se que dentre os produtos a serem obtidos a partir do metano, o metanol é o que apresenta o cenário interno mais crítico. Esta situação é refletida através do contínuo aumento da importação, sem que haja nenhuma sinalização deste déficit ser sanado, através da construção de novas unidades industriais. Por outro lado, o cenário da amônia se mostra estável e, ainda que haja um déficit na produção nacional, a situação atual não se mostra tão crítica, mesmo quando realizada a projeção da demanda até 2030. Analisando-se o cenário petroquímico, em poucos anos a produção de eteno atingirá o seu gargalo, e o maior entrave diagnosticado, para a expansão das centrais produtoras, está relacionado à disponibilidade do insumo. Dentro da abordagem técnica proposta, a modelagem da planta gás-química aponta ser viável concentrar a produção de amônia, metanol e hidrogênio no mesmo pólo e que, para estes produtos, a tecnologia atual encontra-se madura e em estágio avançado. Já a produção de eteno, a partir do etano, não deve estar diretamente vinculada, a princípio, à obtenção dos demais produtos, pelo alto volume de gás natural necessário para liberar a fração de etano ideal para a sustentabilidade do projeto.
This work has as objective to present, through the modeling of a gas-chemical plant and also, through the identification of the current available technologies, the versatility of the use of natural gas as a raw material for the chemical industry, aiming the production of methanol, ammonia and hydrogen, from the fraction methane, as well as in the petrochemical industry, the attainment of ethene from the ethane fraction. Based in a market research, it was determined that amongst the products to be obtained from methane, methanol is the product that presents the most critical internal scenario. This situation is reflected through the continuous increase of the importation; without it there is no signaling that this deficit can be overcome, unless new industrials units are constructed. On the other hand, the ammonia scenario is steady and, despite presenting a deficit in the national production, the current situation does not reveal to very so critical, carried through the projection of the demand up to 2030. Analyzing the petrochemical scene, in a few years the ethene production will reach its pass and the biggest diagnosed impediment is related to the availability of the feedstock. Considering the technique proposal, the modeling of the gas-chemical plant shows the viability of concentrating the production of ammonia, methanol and hydrogen in the same site and that, for these products, the current technologies are mature and very well developed. Already the ethene production, from ethane, does not have to be directly entailed, in principle, to the attainment of the other products, considering the high volume of natural gas necessary to liberate the necessary amount of ethane for the sustainable of the project.

Orientador: Ennio Peres da Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Diversas estratégias têm sido propostas para a introdução do hidrogênio na economia, especificamente no setor de transportes para se reduzir impactos ambientais em comparação com os combustíveis convencionais. Uma das estratégias implica na utilização de Hidrano (misturas de hidrogênio e Gás Natural Veicular), fazendo uso da infraestrutura de postos de GNV e dos veículos já existentes convertidos para uso de GNV. Dessa forma custos e prazos são reduzidos, tornando a introdução do hidrogênio mais promissora economicamente. Esta tese verifica se o hidrogênio pode ser imediatamente introduzido no mercado energético brasileiro através do Hidrano, com frações molares de hidrogênio de 10%, 20% e 30%. O hidrogênio será gerado através da eletrólise da água nos postos de GNV. Foram então determinados os custos do hidrogênio, os preços e a competitividade do Hidrano de forma a atender o perfil de vendas de um posto de porte médio nos Estados de São Paulo e Rio de Janeiro. O preço do Hidrano ao consumidor depende principalmente do preço de seu maior constituinte, o GNV, vendido na época a 1,308 R$/m3 no Estado de São Paulo e a 1,662 R$/m3 no Estado do Rio de Janeiro. O preço do Hidrano ao consumidor varia entre 1,474 R$/m3 e 2,047 R$/m3, dependendo de sua composição e da região. Em vista de sua competitividade em relação aos outros combustíveis automotivos, o Hidrano 10 apresenta bom potencial de introdução no mercado, inclusive do ponto de vista econômico. A competitividade entre os combustíveis no Estado de São Paulo é de 0,280 R$/km para a gasolina, 0,259 R$/km para o etanol, 0,111 R$/km para o GNV, 0,129 R$/km para o Hidrano 10 com tarifação do Grupo B3 e 0,125 R$/km para o Hidrano 10 com tarifação do Grupo A4 Convencional. No Estado do Rio de Janeiro a competitividade é de 0,300 R$/km para a gasolina, 0,311 R$/km para o etanol, 0,141 R$/km para o GNV, 0,161 R$/km para o Hidrano 10 com tarifação do Grupo B3 e 0,157 R$/km para o Hidrano 10 com tarifação do A4 Convencional. Também foram estimados os impactos dessa proposta em termos energéticos e ambientais. Há redução de emissões de CO2 e CO. As emissões de THC serão possivelmente reduzidas e as de NOx aumentadas. A proposta do Hidrano permite às concessionárias de energia elétrica entrarem no mercado de combustíveis veiculares e aumentar suas vendas. Ao mesmo tempo as concessionárias de gás natural terão reduzidas as vendas de GNV no curto prazo, o que deverá ser revertido no médio e longo prazos com os ganhos de rendimento trazidos pelo Hidrano aos veículos
Abstract: Several strategies have been proposed to introduce hydrogen in the economy specifically in the transport sector in order to reduce environmental impacts of conventional fuels. One of the strategies implies in adding hydrogen to compressed natural gas (HCNG), making use of the existing refueling stations and natural gas fleet. Thus the costs and time for the introduction of hydrogen in the economy will be reduced. This thesis verifies whether hydrogen can be immediately introduced into the Brazilian energy market by means of HCNG, containing mole fractions of 10%, 20% and 30% of hydrogen, employed as fuel for conventional vehicles adapted to CNG. Hydrogen will be generated by water electrolysis in the CNG station. Then the cost of hydrogen and the prices and competitiveness of HCNG were determined to meet the sales profile of a midsize gas station in the states of Sao Paulo and Rio de Janeiro. The final price of HCNG depends mainly on the price of its major constituent, CNG, sold at that time for 1,308 R$/m3 in the State of São Paulo and for 1,662 R$/m3 in the State of Rio de Janeiro. The price of HCNG to the consumer varies between 1,474 R$/m3 e 2,047 R$/m3, depending on its composition and the region. In view of its competitiveness compared to other automotive fuels, HCNG 10 (CNG with 10% molar fraction of hydrogen) shows good potential for marketing. The competitiveness among fuels in the State of Sao Paulo is 0,280 R$/km for gasoline, 0,259 R$/km for ethanol, 0,111 R$/km for CNG, 0,129 R$/km for HCNG 10 with power tariff B3 and 0,125 R$/km for HCNG 10 with power tariff A4 Conventional. In the State of Rio de Janeiro the competitiveness is 0,300 R$/km for gasoline, 0,311 R$/km for ethanol, 0,141 R$/km for CNG, 0,161 R$/km for HCNG 10 with power tariff B3 and 0,157 R$/km for HCNG 10 with power tariff A4 Conventional. The energy and environmental impacts of this proposal were also estimated. There is a reduction of CO2 and CO emissions. THC emissions are likely to be reduced and NOx are likely to increase. The proposal of introducing HCNG allows electric utilities to enter the market for vehicular fuels and increase their sales. At the same time, natural gas utilities will have the sales of CNG reduced in the short term, although this trend may be reversed in the medium and long terms with performance gains brought by HCNG to vehicles
Doutorado
Planejamento de Sistemas Energeticos
Doutor em Planejamento de Sistemas Energéticos

O hidrogênio é considerado uma fonte ideal de energia, pois sua combustão não gera contaminantes, apenas água. Dentre os processos disponíveis para produção de hidrogênio, destaca-se a decomposição catalítica do metano, pois, ao contrário do que ocorre na reforma a vapor e na oxidação parcial, nesta rota não há produção de CO. O objetivo deste trabalho é o estudo cinético e a determinação da taxa da reação de decomposição do metano sobre catalisador tipo óxido misto (Cu-Ni-Al) para obtenção de hidrogênio de alta pureza. O catalisador foi separado em quatro faixas de granulometria a fim de se determinar a influência da difusão interna à partícula na velocidade da reação, e o critério de Mears foi utilizado para avaliar o efeito da difusão externa. Os resultados obtidos mostram que, nas condições estudadas, os efeitos difusivos não influenciam significativamente a velocidade da reação. A seguir, a reação foi realizada sob diferentes temperaturas (500 a 600°C) e concentrações de metano (0,5 a 1,2 mol m-3), para determinação da equação da taxa. Observou-se que a reação é de primeira ordem, com uma energia de ativação de 50655 J mol-1. Além do hidrogênio, a reação forma carbono que se deposita na superfície do catalisador causando sua desativação. Os efeitos da regeneração do catalisador por oxidação deste carbono também foram investigados. Repetidos ciclos de reaçãoregeneração foram executados, sendo a regeneração realizada por oxidação do carbono com ar sintético ou por oxidação e redução. A oxidação foi conduzida a diferentes temperaturas (500 a 600°C) e intervalos de duração (20 a 75 min), com a reação ocorrendo em condições severas (600°C e 1,2 mol m-3 de metano). A melhor condição de regeneração, ou seja, aquela que permite um maior número de ciclos com baixa perda de atividade, foi determinada. Observou-se, também, que o carbono depositado apresenta a forma de nanotubos, os quais têm se tornado um dos campos mais ativos da nanociência e da nanotecnologia, devido a suas propriedades excepcionais. Os nanotubos de carbono formados durante a reação foram analisados, quanto a sua estrutura, por Microscopia Eletrônica de Varredura (MEV).
Hydrogen is considered the ideal source of energy, because its combustion doesn't generate pollutants, just water. The catalytic decomposition of methane stands out among the available processes for hydrogen production because, unlike steam reform and partial oxidation, in this route there is not production of CO. The objective of this work is the kinetic study and the reaction rate determination of methane catalytic decomposition over Cu-Ni-Al catalyst for pure hydrogen production. In order to determinate the limiting step, reaction was conducted using four catalyst particle size ranges and the Mears criterion was applied. The external diffusion effects and diffusion in porous catalysts step do not influence significantly the reaction rate in the studied conditions. The reaction was carried out in a thermobalance with different temperatures (500 to 600°C) and methane concentrations (0.5 to 1.2 mol m-3) to determining the reaction rate. It was observed that the reaction is of first order, with activation energy of 50655 J mol-1. The reaction also forms carbon, which is deposited on the catalyst surface causing deactivation. The carbon oxidation for catalyst regeneration was also investigated. Repeated reaction-regeneration cycles were carried out, being the regeneration composed by oxidation or by oxidation and reduction. The oxidation was carried out at different temperatures (500 to 600°C) and times (20 to 75min), with the reaction happening in severe conditions (600°C and methane concentration of 1.2 mol m-3). The best regeneration condition, that is, the condition that allows a larger number of cycles with low activity loss, it was determined. It was also observed that the deposited carbon is in the nanotubes form, which has exceptional properties. The structure of carbon nanotubes formed during the reaction was analyzed by Scanning Electron Microscopy (SEM).

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CNPQ
A reforma a vapor de metano é a principal via de produção de hidrogênio e de gás de síntese. Industrialmente, esta reação ocorre sobre um catalisador de níquel suportado em alumina que, embora apresente alta atividade e seletividade, além de baixo custo, tem a desvantagem de apresentar uma curta vida útil, devido à deposição de coque. Por outro lado, os metais nobres apresentam mais alta atividade catalítica e mais resistência à deposição de coque e à sinterização do que o catalisador comercial. Além disso, a adição de magnésio à alumina é uma boa opção para evitar a deposição de coque e, também, aumentar a resistência térmica do sólido. Considerando essas vantagens estudou-se, neste trabalho, o efeito da adição de magnésio sobre as propriedades de um catalisador de platina suportada em alumina, a fim de desenvolver novos e eficientes catalisadores para produzir hidrogênio, a partir da reforma a vapor do metano. As amostras com razões molares Al/Mg=0,2, 2 e 5 foram preparadas pelo método de precipitação e impregnadas com 1 % (m/m) de platina. Os sólidos foram caracterizados por análise química, termogravimetria, análise térmica diferencial, espectroscopia de infravermelho com transformadas de Fourier, difração de raios X, redução à temperatura programada, medida da área superficial específica e de porosidade, espectroscopia de infravermelho com transformadas de Fourier usando monóxido de carbono como molécula sonda, dessorção à temperatura programada de amônia adsorvida, espectroscopia fotoeletrônica de raios X e medida do teor de carbono. Os catalisadores foram avaliados a 600 oC e 1 atm, sob uma razão vapor/metano = 4. Os catalisadores mais ricos em alumínio (sem magnésio e com Al/Mg= 5) mostraram a estrutura da γ-alumina, enquanto os demais mostraram a estrutura da periclase. A presença de magnésio diminuiu a área superficial específica da alumina devido à mudança de estrutura. A interação entre a platina e o suporte também aumentou com a quantidade de magnésio, que também alterou a natureza e a quantidade dos sítios ácidos nos sólidos. De modo geral, o magnésio aumentou a quantidade de platina na superfície dos catalisadores e a quantidade de átomos de platina ricos em elétrons, como conseqüência do aumento de sua interação com o suporte. Todos os catalisadores foram ativos na reforma a vapor do metano e seletivos ao hidrogênio. Numa tendência geral, o magnésio favoreceu a atividade e seletividade dos catalisadores. A amostra com Mg/Al= 5 foi o catalisador mais ativo e seletivo, o que pode ser relacionado à sua área superficial específica mais alta, assim como ao teor mais elevado de átomos de platina mais ricos em elétrons na superfície.
Methane steam reforming is the main route to produce hydrogen and synthesis gas. Industrially, this reaction occurs on an alumina-supported nickel catalyst which, although shows high activity and selectivity, besides low price, it has the disadvantage of showing short life because of coke deposition. On the other hand, noble metals show high activity and are more resistant against coke deposition and sintering than the commercial catalyst. Besides, the addition of magnesium to alumina seems to be a good option to prevent coke deposition and also to increase the thermal resistance. Considering these advantages, the effect of magnesium addition on the properties of alumina-supported platinum was studied in this work, aiming to develop new efficient catalysts to produce hydrogen by methane steam reforming. Samples with Al/Mg (molar) = 0.2, 2 and 5 were prepared by precipitation method and impregnated with 1% (w/w) platinum. The solids were characterized by chemical analysis, thermogravimetry, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, temperature programmed reduction, specific surface area and porosity measurement, Fourier transform infrared spectroscopy using carbon monoxide as probe molecule, temperature programmed desorption of ammonia, X-ray photoelectron spectroscopy and carbon content measurement. The catalysts were evaluated at 600 oC and 1 atm, under a steam to methane molar ratio of 4. The catalysts richer in alumina (magnesium-free and with Al/Mg= 5 and 2) showed the γ-alumina structure while the others showed the periclase structure. The presence of magnesium increased the specific surface area of alumina because of the change in the structure. The interaction between platinum and the support also increased with the amount of magnesium which also changed the kind and the amount of acidic sites. As a whole magnesium also increased the amount of platinum on the catalyst surface and of electron-rich platinum atoms, as a consequence of the increase of its interaction with the support. All catalysts were active in methane steam reforming and selective to hydrogen. In a general tendency, magnesium favored the activity and selective of the catalysts. The sample with Al/Mg= 5 was the most active and selective catalyst, a fact that was related to its highest specific surface area as well as to the highest amount of electron-richest platinum atoms on the surface.

The exploitation and development of offshore oil & gas fields continue to be one of the main source to supply energy worldwide. However, existing and new projects may involve specific geographic areas with safety challenges due to the presence of natural gas, mainly Methane (CH4), containing a certain amount of Hydrogen Sulphide (H2S) in the extracted hydrocarbons (sour gas). Indeed, the combined effect of flammability and toxicity of such gases has the critical potential to increase the hazard level in the offshore installation aggravating the consequences for human and assets. The present work aims at the consequences analysis related to the release of sour gas (CH4/H2S) on an offshore production facility, by considering different H2S fractions in the gas composition. The analysis was based on the estimation of safety distances for the physical effects of accident scenarios with respect to personnel, equipment and facility structures. Two different approaches implemented into consequences modelling software, the Process Hazard Analysis Software Tool (PHAST), which is based on integral and lumped parameter model, and the Fire Dynamic Simulator (FDS), which is ascribed to the Computational Fluid Dynamic model, hence based on distributed parameter model. A case study concerning an actual offshore, multi-level platform for gas production was considered. Large releases from two different process equipment were simulated for three mixtures with different amount of H2S, starting from specific release points. The results showed that the H2S content is not an effective factor for the safety distance in the case of ignition of the gas cloud, hence in the case of fires. Also, the presence of obstructions slightly affects the damage distances for fires. On the contrary, the safety distance from the release point can be strongly affected by the presence of H2S concentration higher than 1%v.

Orientadores: Ênnio Peres da Silva, Kamal Abdel Radi Ismail
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Ao avaliar a evolução do uso da energia pelo homem, percebe-se uma tendência à utilização de combustíveis com menos carbono e mais hidrogênio. Atualmente, observa-se um empenho pela utilização de combustíveis gasosos, como o gás natural, que possui uma relação de 4 átomos de hidrogênio para 1 átomo de carbono. Esta evolução permite estimar a utilização do hidrogênio gasoso para o futuro. Por se tratar de um vetor energético e não de uma fonte de energia, o hidrogênio precisa ser extraído de algum composto para ser utilizado. Examinando-se a literatura pertinente dos últimos anos, verifica-se que há em todo o mundo um grande esforço e uma grande expectativa quanto ao uso energético do hidrogênio em células a combustível, já que a eficiência destes equipamentos é superior à eficiência dos dispositivos tradicionais que utilizam à combustão. Sua aplicação se dá em diversos sistemas energéticos, estacionários ou móveis. Devido á exigência de elevada pureza para o hidrogênio utilizado em células a combustível do tipo PEM, a produção de hidrogênio a partir do processo de reforma de gás natural e o sistema de purificação deste hidrogênio tem sido estudado pelos principais centros de pesquisa nacionais. Por se tratar de umas das formas mais baratas para obtenção de hidrogênio para aplicação em células a combustível, o conhecimento desta tecnologia poderá conduzir à competitividade do uso energético do hidrogênio com um menor custo num menor prazo, o que a torna uma tecnologia estratégica. O objetivo geral desta dissertação é apresentar os principais processos de purificação do gás de síntese proveniente da reforma do gás natural para o fornecimento de hidrogênio com pureza suficiente para uso em células a combustível do tipo PEM e apresentar as considerações teóricas e experimentais sobre o funcionamento do sistema de purificação construído pelo Laboratório de Hidrogênio da Unicamp para desenvolvimento desta dissertação
Abstract: Evaluating the evolution of energy use by humanity it is observed a tendency to use fuels with lower carbon content and more hydrogen. Currently, there is a commitment to use fuels such as natural gas that has a ratio of 4 hydrogen atoms to 1 carbon atom. That evolution allows the estimation of gaseous hydrogen use for the future. Hydrogen is an energy vector, not an energy source, and then it must be extracted from a compound to feed fuel cells. The literature of recent years shows that there is a great effort and a huge expectation for the use of fuel cells which achieve higher efficiencies than traditional combustion devices. Fuel cells can be used in stationary, automotive or portable energy systems and its manufacturing technology has left laboratories and research centers is now being developed by companies with large investments. Since PEM fuel cells require high purity hydrogen, the hydrogen production from natural gas reforming process and the hydrogen purification systems have been studied by Brazilian research centers. Because this process is one of the cheapest methods to obtain hydrogen for use in fuel cells, the knowledge of this technology could lead to the competitive use of hydrogen energy at a lower cost in a shorter term, making it a strategic technology. The general objective of this dissertation is to present the main processes for the purification of synthesis gas from the reforming of natural gas to supply hydrogen with sufficient purity for its use in PEM fuel cells and present the theoretical and experimental considerations about the purification system built by the Hydrogen Laboratory at Unicamp for the development of this dissertation
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The compressed natural gas (CNG) is a fossil derivative mostly comprised of light hydrocarbons (methane, ethane, and propane), which has great energy importance for modern society. Considering the growing demand for CNG, it is also necessary to an effective control of the composition of the majority gases, which are mainly responsible for the energy efficiency of this fuel. The composition of these gases in CNG follows a certain pattern of conformity (control group) established by the ANP (National Agency of Petroleum, Natural Gas and Biofuels), to ensure the energy efficiency of CNG sold in Brazil. This work proposes the development of a methodology for automatic preparation of gas mixtures of methane standards, ethane and propane, in order to chromatographic determination of these gases levels in CNG, employing elaborate calibration models and validated by analysis of variance (ANOVA) and test recovery. The automatic system is of the dynamic type and is fully controlled by a program in order to prepare, as programmed by the user, binary mixtures of nitrogen / methane / nitrogen and nitrogen ethane / propane at levels (at fraction mol / mol) ranging in order to obtain good calibration models that consider the concentrations of these gases in the CNG. The evaluation methodology using ANOVA was quite satisfactory, the models built for the three gases methane, ethane and propane showed a high correlation (R2> 0.99) and significant in the regression, and showed no lack of fit and systematic variation at the residual plot. The performance parameters obtained from built models had lower detection and quantification limits 10-2 to 10-1, the analytical frequency was 4 samples per hour. A recovery study , involving three gas mixtures of certified composition and Natural Gas sample Vehicle (NGV) was also performed and the percentage values mean were 99.7 ± 3.1; 100.7 ± 4.4 and 98.0 ± 5.8 for methane, ethane and propane, respectively. The conclusion is based on the recovery values, as well as ANOVA, the proposed method was validated, with satisfactory precision and accuracy.
O gás natural veicular (GNV) é um derivado fóssil composto majoritariamente por hidrocarbonetos leves (metano, etano e propano), que tem grande importância energética para a sociedade moderna. Considerando a crescente demanda de GNV, se faz necessário, também, um efetivo controle da composição destes gases majoritários, que são os principais responsáveis pela eficiência energética deste combustível. A composição destes gases em GNV segue um determinado padrão de conformidade (faixa de controle) estabelecido pela ANP (Agência Nacional do Petróleo, Gás Natural e Biocombustíveis), de modo a garantir a eficiência energética do GNV comercializado no Brasil. Este trabalho propõe o desenvolvimento de uma metodologia para preparação automática de misturas gasosas padrões de metano, etano e propano, visando à determinação cromatográfica dos teores destes gases em GNV, empregando modelos de calibração elaborados e validados por análise de variância (ANOVA) e teste de recuperação. O sistema automático é do tipo dinâmico e é totalmente controlado por um programa de modo a preparar, conforme programado pelo usuário, misturas binárias de nitrogênio/metano, de nitrogênio/etano e de nitrogênio/propano, com teores (em fração mol/mol) que variam de modo a se obter bons modelos de calibração que contemplem as concentrações desses gases no GNV. A avaliação da metodologia por meio da ANOVA foi bastante satisfatória, os modelos construídos para os três gases metano, etano e propano apresentaram uma alta correlação (R2 > 0,99) e significância na regressão, e não demonstraram falta de ajuste e variação sistemática no gráfico dos resíduos. Os parâmetros de desempenho obtidos a partir dos modelos construídos tiveram limites de detecção menores que 10-2 e de quantificação menores que 10-1, a frequência de amostragem foi 4 amostras por hora. Um estudo de recuperação, envolvendo três misturas gasosas de composição certificada e uma amostra de Gás Natural Veicular (GNV), foi também realizado e os valores médios percentuais obtidos foram de 99,7 ± 3,1; 100,7 ± 4,4 e 98,0 ± 5,8 para o metano, etano e propano, respectivamente. Conclui-se com base nos valores de recuperação, bem como na ANOVA, que o método proposto foi devidamente validado, apresentando uma satisfatória precisão e exatidão.

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The natural gas (NG) is a clean energy source and found in the underground of porous rocks, associated or not to oil. Its basic composition includes methane, ethane, propane and other components, like carbon dioxide, nitrogen, hydrogen sulphide and water. H2S is one of the natural pollutants of the natural gas. It is considered critical concerning corrosion. Its presence depends on origin, as well as of the process used in the gas treatment. It can cause problems in the tubing materials and final applications of the NG. The Ag?ncia Nacional do Petr?leo sets out that the maximum concentration of H2S in the natural gas, originally national or imported, commercialized in Brazil must contain 10 -15 mg/cm3. In the Processing Units of Natural Gas, there are used different methods in the removal of H2S, for instance, adsorption towers filled with activated coal, zeolites and sulfatreat (solid, dry, granular and based on iron oxide). In this work, ion exchange resins were used as adsorbing materials. The resins were characterized by thermo gravimetric analysis, infrared spectroscopy and sweeping electronic microscopy. The adsorption tests were performed in a system linked to a gas-powered chromatograph. The present H2S in the exit of this system was monitored by a photometrical detector of pulsing flame. The electronic microscopy analyzes showed that the topography and morphology of the resins favor the adsorption process. Some characteristics were found such as, macro behavior, particles of variable sizes, spherical geometries, without the visualization of any pores in the surface. The infrared specters presented the main frequencies of vibration associated to the functional group of the amines and polymeric matrixes. When the resins are compared with sulfatreat, under the same experimental conditions, they showed a similar performance in retention times and adsorption capacities, making them competitive ones for the desulphurization process of the natural gas
O g?s natural (GN) ? uma fonte de energia limpa encontrada no subsolo de rochas porosas, associado ou n?o ao petr?leo. Sua composi??o b?sica inclui metano, etano, propano e outros componentes, como di?xido de carbono, nitrog?nio, ?cido sulf?drico e ?gua. H2S ? um dos poluentes naturais do g?s natural. ? considerado cr?tico no que se refere ? corros?o. Sua presen?a depende da origem, bem como do processo usado no tratamento do g?s. Ele pode acarretar problemas nas tubula??es e aplica??es finais do GN. A Ag?ncia Nacional de Petr?leo estabelece que a concentra??o m?xima de H2S no g?s natural, de origem nacional ou importado, comercializado no Brasil contenha no m?ximo 10 15 mg/m3. Nas Unidades de Processamento do G?s Natutal, diferentes m?todos s?o usados na remo??o de H2S, por exemplo, em torres de adsor??o recheadas com carv?o ativo, ze?litas e Sulfatreat (s?lido, seco, granular e baseado em ?xido de ferro). Neste trabalho, resinas de troca-i?nica foram usadas como material adsorvente. As resinas foram caracterizadas por an?lise termogravim?trica, espectroscopia de infravermelho e microscopia eletr?nica de varredura. Os ensaios de adsor??o foram realizados em um sistema acoplado a um cromat?grafo a g?s. O H2S presente na sa?da do sistema foi monitorado por um detector fotom?trico de chama pulsante. As an?lises de microscopia eletr?nica demonstraram que a topografia e morfologia das resinas favorecem o processo de adsor??o. Caracter?sticas como comportamento macro, part?culas de tamanhos variados, geometrias esf?ricas, sem a visualiza??o de poros na superf?cie, foram encontrados. Os espectros de infravermelho apresentaram as principais freq??ncias de vibra??o associadas aos grupos funcionais das aminas e matrizes polim?ricas. Quando comparadas ao sulfatreat, sob as mesmas condi??es experimentais, as resinas demonstraram semelhante desempenho em tempos de reten??o e capacidade de adsor??o, tornando-se competitiva para o processo de dessulfuriza??o do g?s natural

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The natural gas (NG) is a clean energy source and found in the underground of porous rocks, associated or not to oil. Its basic composition includes methane, ethane, propane and other components, like carbon dioxide, nitrogen, hydrogen sulphide and water. H2S is one of the natural pollutants of the natural gas. It is considered critical concerning corrosion. Its presence depends on origin, as well as of the process used in the gas treatment. It can cause problems in the tubing materials and final applications of the NG. The Ag?ncia Nacional do Petr?leo sets out that the maximum concentration of H2S in the natural gas, originally national or imported, commercialized in Brazil must contain 10 -15 mg/cm3. In the Processing Units of Natural Gas, there are used different methods in the removal of H2S, for instance, adsorption towers filled with activated coal, zeolites and sulfatreat (solid, dry, granular and based on iron oxide). In this work, ion exchange resins were used as adsorbing materials. The resins were characterized by thermo gravimetric analysis, infrared spectroscopy and sweeping electronic microscopy. The adsorption tests were performed in a system linked to a gas-powered chromatograph. The present H2S in the exit of this system was monitored by a photometrical detector of pulsing flame. The electronic microscopy analyzes showed that the topography and morphology of the resins favor the adsorption process. Some characteristics were found such as, macro behavior, particles of variable sizes, spherical geometries, without the visualization of any pores in the surface. The infrared specters presented the main frequencies of vibration associated to the functional group of the amines and polymeric matrixes. When the resins are compared with sulfatreat, under the same experimental conditions, they showed a similar performance in retention times and adsorption capacities, making them competitive ones for the desulphurization process of the natural gas
O g?s natural (GN) ? uma fonte de energia limpa encontrada no subsolo de rochas porosas, associado ou n?o ao petr?leo. Sua composi??o b?sica inclui metano, etano, propano e outros componentes, como di?xido de carbono, nitrog?nio, ?cido sulf?drico e ?gua. H2S ? um dos poluentes naturais do g?s natural. ? considerado cr?tico no que se refere ? corros?o. Sua presen?a depende da origem, bem como do processo usado no tratamento do g?s. Ele pode acarretar problemas nas tubula??es e aplica??es finais do GN. A Ag?ncia Nacional de Petr?leo estabelece que a concentra??o m?xima de H2S no g?s natural, de origem nacional ou importado, comercializado no Brasil contenha no m?ximo 10 15 mg/m3. Nas Unidades de Processamento do G?s Natutal, diferentes m?todos s?o usados na remo??o de H2S, por exemplo, em torres de adsor??o recheadas com carv?o ativo, ze?litas e Sulfatreat (s?lido, seco, granular e baseado em ?xido de ferro). Neste trabalho, resinas de troca-i?nica foram usadas como material adsorvente. As resinas foram caracterizadas por an?lise termogravim?trica, espectroscopia de infravermelho e microscopia eletr?nica de varredura. Os ensaios de adsor??o foram realizados em um sistema acoplado a um cromat?grafo a g?s. O H2S presente na sa?da do sistema foi monitorado por um detector fotom?trico de chama pulsante. As an?lises de microscopia eletr?nica demonstraram que a topografia e morfologia das resinas favorecem o processo de adsor??o. Caracter?sticas como comportamento macro, part?culas de tamanhos variados, geometrias esf?ricas, sem a visualiza??o de poros na superf?cie, foram encontrados. Os espectros de infravermelho apresentaram as principais freq??ncias de vibra??o associadas aos grupos funcionais das aminas e matrizes polim?ricas. Quando comparadas ao sulfatreat, sob as mesmas condi??es experimentais, as resinas demonstraram semelhante desempenho em tempos de reten??o e capacidade de adsor??o, tornando-se competitiva para o processo de dessulfuriza??o do g?s natural

The awareness of the effect emissions have on the environment and climate has risen in the last decades. This has caused strict regulations of greenhouse gas emissions. Greenhouse gases cause global warming which may have devastating environmental effects. Most of the fuels commercially available today are fossil fuels. There are two major effects of using fuels with fossil origin; the source will eventually drain and the usage results in an increase of greenhouse gases in the atmosphere. Fuels that are created from a renewable feedstock are often referred to as alternative fuels and under ideal conditions they are greenhouse gas neutral, meaning that the same amount of greenhouse gases is released during combustion as the source of the fuel have absorbed during its growth period. This evaluation method is known as a well-to-wheel analysis which besides emissions also evaluates energy efficiencies during both the production and the combustion phases.

By evaluating results of well-to-wheel analyses along with fuel properties and engine concept characteristics, this report presents which driving scenario that is suitable for different powertrain configurations. For example, vehicles operating in high populated areas, as cities, have a driving scenario that includes low velocities and multiple stops while vehicles in low populated areas often travel long distances in higher speeds. This implies that different powertrains are suitable in different regions. By matching favorable properties of a certain powertrain to the properties important to the actual driving scenario this report evolves a fuel infrastructure that is suitable in Sweden.

Porous organic polymers containing nitrogen-rich building units are among the most promising materials for selective CO2 capture and separation applications that impact the environment and the quality of methane and hydrogen fuels. The work described herein describes post-synthesis modification of Nanoporous Organic Frameworks (NPOFs) and its impact on gas storage and selective CO2 capture. The synthesis of NPOF-4 was accomplished via a catalysed cyclotrimerization reaction of 1,3,5,7-tetrakis(4-acetylphenyl)adamantane in Ethanol/Xylenes mixture using SiCl4 as a catalyst. NPOF-4 is microporous and has high surface area (SABET = 1249 m2 g-1). Post-synthesis modification of NPOF-4 by nitration afforded (NPOF-4-NO2) and subsequent reduction resulted in an amine-functionalized framework (NPOF-4-NH2) that exhibits improved gas storage capacities and high CO2/N2 (139) and CO2/CH4 (15) selectivities compared to NPOF-4 under ambient conditions. These results demonstrate the impact of nitro- and amine- pore decoration on the function of porous organic materials in gas storage and separation application.

A presente pesquisa foi desenvolvida para avaliar as potencialidades das células de combustível como tecnologia em si, inclusive os beneficios econômicos que se podem ter por meio do suprimento de energia elétrica se comparada com o aproveitamento da mesma por meio da rede pública. Além de uma parte descritiva do estado de arte da tecnologia, a presente dissertação foi focada em duas partes: a primeira trata de um estudo experimental onde uma célula, a membrana polimérica, foi conectada a um inversor, permitindo assim de fornecer energia elétrica na rede pública. Na segunda parte foi realizada uma avaliação engenhero-econômica com uma Célula de Combustível de Ácido Fosfórico para o aproveitamento da energia elétrica com cogeração de calor para as condições de mercado brasileiro. O primeiro estudo mostrou como seja possível abastecer uma célula (neste caso alimentada por hidrogênio) para fornecer continuamente energia elétrica na rede, onde necessário ou onde seja impossível para o usuário se conectar a rede pública. O segundo estudo, por sua vez, mostrou que atualmente a células de combustível de média temperatura de Ácido Fosfórico (PAFC) não é uma tecnologia ainda madura e que é viável economicamente somente em aplicações de nicho, por exemplo setores indústriais eletro-intensivos e com necessidade de energia termica também. Todavia, projeções futuras baseadas em curvas de aprendizados e a queda do preço do gás natural mostram como a expansão da tecnologia e a possibilidade de acessar um combustível barato podem abrir futuro para a PAFC mundialmente.
This Masters dissertation aims to study technical potentialities of Fuel Cell technology, including the economical benefits that can provide compared with public grid as well. Thus, the dissertation has been focused in two main parts: the first concerns in an experimental approach to supply electrical power to the public grid using a Polymer Electrolyte Membrane Fuel Cell (PEMFC), while the second one presents a global (from an engineering and economic point-of-view) assessment of a Phosphoric Acid Fuel Cell (PAFC) for the co-generation of heat with electrical energy in Brazil. The first study has been accomplished connecting a PEMFC with a power inverter to the public grid. It has been proved experimentally that Fuel Cell is an alternative device that, as long as fuel is fed, may provide electrical energy continuously and more efficiently than traditional devices. The second study has been focused in the so-called Phosphoric Acid Fuel Cell (PAFC) that, being a Medium Temperature Fuel Cell, beyond to supply electrical energy, may be used for co-generation of thermal energy. Through this study it has been showed that, at the current state-of-art, PAFC is is not already a mature technology and it becomes economically viable only for niche market applications, represented by the industrial sectors with high base load power and continuous thermal energy demand. However, accumulated knowledge expressed by learning curve and natural gas shock price caused by possible LNG supplying and shale gas recovery are the two main factors that may turn investment in PAFC profitable worldwide.

The theory of the abyssal abiotic petroleum origin considers oil and natural gas to begenerated in the Earth’s upper mantle. Hydrocarbons migrate further through the deep faults into the Earth’s crust, where they can form oil and gas deposits in any kind of rock in any kind of structural position. Until recently one of the main obstacles for further development of this theory has been the lack of the data covering processes of generation and transformations of hydrocarbons. Experimental data, presented in this thesis, confirms the possibility of hydrocarbons formation from mantle inorganic compounds (water, Fe, CaCO3 or graphite) at temperature and pressure of the upper mantle (1500 K and 5 GPa). Experiments were carried out in CONAC high pressure device and multianvil apparatus BARS. Compositions of received gas mixtures were similar to natural gas. Quantity of hydrocarbons depended on the cooling regime of reaction mixture under pressure. Slow cooling favored higher quantity. We found that donor of carbon (CaCO3 or graphite) determines formation of “dry” (methane-rich) gas or “wet” (light hydrocarbons-rich) gas. Experiments in laser-heated diamond anvil cells showed that methane and ethane partially react under upper mantle thermobaric conditions (2-5 GPa, 1000-1500 K) to form mixture of hydrocarbons: methane, ethane, propane and n-butane – main compounds of natural gas. Similarity of final product mixture obtained from methane and ethane means thermodynamic stability of hydrocarbons in the thermobaric conditions of the upper mantle and equilibrium character of the observed processes.
QC 20101203

Les inclusions fluides naturelles peuvent fournir des informations quantitatives précieuses pour reconstruire les conditions de circulation des paléofluides. CO₂, CH₄ et N₂ sont les espèces gazeuses majoritaires le plus souvent rencontrées dans divers environnements géologiques. Cependant les données d’étalonnage des mélanges constitués de ces espèces pour une quantification de leurs propriétés PVX ne sont pas encore complètement établies. L'utilisation des données de calibration disponible dans la littérature peut donc entraîner des erreurs significatives. L'objectif central de ce travail de thèse est d’apporter des données d’étalonnage du signal Raman des gaz CO₂, CH₄, N₂ et de leurs mélanges, sur une gamme de pression de 5 à 600 bars, afin de pouvoir déterminer simultanément les propriétés PVX à une température fixée. Pour cela, des mélanges de gaz ont été préparés à haute pression par le biais d'un mélangeur (GasMix AlyTech) couplé avec un système de pressurisation développé au laboratoire GeoRessources. Des analyses in situ Raman des mélanges de gaz ont été réalisées dans des conditions contrôlées en utilisant le système HPOC couplé avec un microcapillaire transparent placé sur une platine microthermométrique (Linkam CAP500). L’incertitude des mesures des propriétés PVX à 22 ou 32 °C à partir de nos équations d’étalonnage est de < 1 mol%, ~ ± 20 bars et ~ ± 0,02 g.cm-³ pour la composition, la pression et la densité, respectivement. Un autre objectif du projet est d'interpréter la tendance de variation de la position du pic du N₂ et/ou CH₄ pour une compréhension approfondie. Deux modèles théoriques, i.e., le potentiel de Lennard-Jones 6-12 et le modèle « Perturbed hard-sphere fluid » ont été utilisés pour évaluer quantitativement la contribution des forces d'interaction intermoléculaire attractives et répulsives aux décalages des bandes de CH₄ et N₂. Un modèle prédictif a été proposé pour prédire la tendance de la variation de la position du pic du CH₄ jusqu'à 3000 bars en fonction de la pression et de la composition. En fin, l'applicabilité de nos données d'étalonnage aux autres systèmes gazeux ou dans d’autres laboratoires est discutée et évaluée. Des nouvelles données d’étalonnage universelles applicables dans d’autres laboratoires sont fournies. Un programme de calcul « FRAnCIs » avec une interface utilisateur a été développé pour rendre l'utilisation de nos données d'étalonnage accessibles au plus grand nombre
Quantitative knowledge of species trapped within fluid inclusions provides key information to better understand geological processes as well as to reconstruct the conditions of paleofluid circulation. CO₂, CH₄, and N₂ are among the most dominant gas species omnipresent in various geological environments, but their quantitative PVX calibration data are not fully established yet. Using the previously published data can therefore lead to non-quantified errors, especially when applied to geological fluids containing generally several substances at elevated pressure and density. The aim of this work is to provide accurate calibration data for the simultaneous determination of PVX properties of pure gases or any binary and ternary mixtures of CO₂, CH₄, and N₂ over 5 to 600 bars at a fixed temperature, directly from Raman spectra. For this, gas mixtures were prepared and compressed using a mixer (GasMix AlyTech) coupled with a homemade pressurization system. Raman in situ analyses of gas mixtures were performed at controlled conditions using an improved HPOC system (High-Pressure Optical Cell) with a transparent microcapillary containing the prepared gas mixtures, placed on a heating-cooling stage (Linkam CAP500). Overall, the uncertainty of the measurement of the PVX properties of fluid inclusions from our calibration equations at 22 or 32 °C is < ± 1 mol%, ~ ± 20 bars, and ~ ± 0.02 g.cm-³ for molar proportion, pressure and density, respectively. The ensuing aim of the project is to interpret the variation trends of the peak position of the CH₄ and N₂ ν1 band for an in-depth understanding. Two theoretical models, i.e., Lennard-Jones 6-12 potential energy approximation and Perturbed hard-sphere fluid model were involved to quantitatively assess the contribution of the attractive and repulsive intermolecular interaction forces to the pressure-induced frequency shifts. A predictive model was also provided to predict the variation trend of the CH₄ ν1 band over a pressure range up to 3000 bars as a function of pressure and composition. Furthermore, the applicability of our calibration data to other laboratories and apparatus and to gas mixtures that contain a small amount of other species (e.g., H2, H2S) was discussed and evaluated. New universal calibration data applicable for other laboratories were then provided. A computer program “FRAnCIs” was also developed to make the application of our calibration data as convenient as possible via a user-friendly interface

Cette thèse est une contribution aux travaux en cours sur la valorisation du méthane, compte tenu de son importance potentielle comme matière première de l'industrie chimique. Le but de ce travail est de progresser dans la compréhension de la réaction de couplage thermique du méthane. Ce mémoire peut être divisé en deux parties: expérimentation et modélisation. Nous avons pyrolysé des mélanges CH₄-h₂ dans un réacteur considéré comme fonctionnant en régime piston. La température de pyrolyse varie entre 1200°C et 1400°C avec un temps de séjour compris entre 0,1 et 1 seconde sous 1 atmosphère. Dans ces conditions, la pyrolyse conduit a la formation d'acétylène, d'éthylène, de benzène et d'hydrogène comme produits principaux et à la formation de coke comme produit indiscernable. L'enjeu global de cette étude est donc de trouver le meilleur compromis entre une conversion suffisante du méthane et un taux de coke acceptable. Dans ce but les effets de la température, du temps de séjour, du taux de dilution par l'hydrogène et de la nature du réacteur ont été quantifiés. La réaction du cokage a également été étudiée et nous avons montré l'existence de plusieurs types de coke sur les parois du réacteur. L'effet de l'hydrogène sur les rendements en C₂et en coke a été simulé a l'aide d'un schéma cinétique et d'un code de calcul (chemkin)

L'optimisation de l'exploitation d'un réseau de transport de gaz naturel (RTGN) est typiquement un problème d'optimisation multiobjectif, faisant intervenir notamment la minimisation de la consommation énergétique dans les stations de compression, la maximisation du rendement, etc. Cependant, très peu de travaux concernant l'optimisation multiobjectif des réseaux de gazoducs sont présentés dans la littérature. Ainsi, ce travail vise à fournir un cadre général de formulation et de résolution de problèmes d'optimisation multiobjectif liés aux RTGN. Dans la première partie de l'étude, le modèle du RTGN est présenté. Ensuite, diverses techniques d'optimisation multiobjectif appartenant aux deux grandes classes de méthodes par scalarisation, d'une part, et de procédures évolutionnaires, d'autre part, communément utilisées dans de nombreux domaines de l'ingénierie, sont détaillées. Sur la base d'une étude comparative menée sur deux exemples mathématiques et cinq problèmes de génie des procédés (incluant en particulier un RTGN), un algorithme génétique basé sur une variante de NSGA-II, qui surpasse les méthodes de scalarisation, de somme pondérée et d'ε-Contrainte, a été retenu pour résoudre un problème d'optimisation tricritère d'un RTGN. Tout d'abord un problème monocritère relatif à la minimisation de la consommation de fuel dans les stations de compression est résolu. Ensuite un problème bicritère, où la consommation de fuel doit être minimisée et la livraison de gaz aux points terminaux du réseau maximisée, est présenté ; l'ensemble des solutions non dominées est répresenté sur un front de Pareto. Enfin l'impact d'injection d'hydrogène dans le RTGN est analysé en introduisant un troisième critère : le pourcentage d'hydrogène injecté dans le réseau que l'on doit maximiser. Dans les deux cas multiobjectifs, des méthodes génériques d'aide à la décision multicritère sont mises en oeuvre pour déterminer les meilleures solutions parmi toutes celles déployées sur les fronts de Pareto
The optimization of a natural gas transportation network (NGTN) is typically a multiobjective optimization problem, involving for instance energy consumption minimization at the compressor stations and gas delivery maximization. However, very few works concerning multiobjective optimization of gas pipelines networks are reported in the literature. Thereby, this work aims at providing a general framework of formulation and resolution of multiobjective optimization problems related to NGTN. In the first part of the study, the NGTN model is described. Then, various multiobjective optimization techniques belonging to two main classes, scalarization and evolutionary, commonly used for engineering purposes, are presented. From a comparative study performed on two mathematical examples and on five process engineering problems (including a NGTN), a variant of the multiobjective genetic algorithm NSGA-II outmatches the classical scalararization methods, Weighted-sum and ε-Constraint. So NSGA-II has been selected for performing the triobjective optimization of a NGTN. First, the monobjective problem related to the minimization of the fuel consumption in the compression stations is solved. Then a biojective problem, where the fuel consumption has to be minimized, and the gas mass flow delivery at end-points of the network maximized, is presented. The non dominated solutions are displayed in the form of a Pareto front. Finally, the study of the impact of hydrogen injection in the NGTN is carried out by introducing a third criterion, i.e., the percentage of injected hydrogen to be maximized. In the two multiobjective cases, generic Multiple Choice Decision Making tools are implemented to identify the best solution among the ones displayed of the Pareto fronts

Дипломна магістерська робота присвячена удосконаленню циклічного процесу адсорбційного поділу газової суміші з отриманням водню, аналізу математичної моделі технологічного процесу виробництва водню та обґрунтуванню, розробці і дослідженню автоматизованої системи керування технологічним процесом виробництва водню. Досліджені моделі, методи і алгоритми автоматизованого керування, що забезпечують отримання водню методом адсорбційного поділу газових сумішей з циклічно мінливим тиском при виконанні заданих технологічних обмежень. В дослідженнях використовувались методи системного аналізу, математичного моделювання, оптимізації, теорії керування, теорії процесів і апаратів хімічної технології. За результатами досліджень розроблена структура автоматизованої системи керування технологічним процесом виробництва водню, проведено дослідження закономірностей динаміки адсорбційних процесів з циклічною зміною тиску при дії різних збурень та запропоновано застосування адаптивної системи керування циклічним процесом адсорбційного поділу газової суміші з отриманням водню.
Дипломная магистерская работа посвящена усовершенствованию циклического процесса адсорбционного разделения газовой смеси с получением водорода, анализу математической модели технологического процесса производства водорода и обоснованию, разработке и исследованию автоматизированной системы управления технологическим процессом производства водорода. Исследованы модели, методы и алгоритмы автоматизированного управления, обеспечивающие получение водорода методом адсорбционного разделения газовых смесей с циклически изменяющимся давлением при выполнении заданных технологических ограничений. В исследованиях использовались методы системного анализа, математического моделирования, оптимизации, теории управления, теории процессов и аппаратов химической технологии. По результатам исследований разработана структура автоматизированной системы управления технологическим процессом производства водорода, проведено исследование закономерностей динамики адсорбционных процессов с циклическим изменением давления при воздействии различных возмущений и предложено применение адаптивной системы управления циклическим процессом адсорбционного разделения газовой смеси с получением водорода.
Thesis is devoted to improving the cyclic proccss of adsorption separation of a gas mixture with hydrogen production, analysis of the mathematical model of the technological proccss of hydrogen production and substantiation, development and research of an automated control system for the technological proccss of hydrogen production. Models, methods and algorithms of automated control, which provide hydrogen production by the method of adsorption separation of gas mixtures with cyclically variable pressure at performance of the set technological restrictions, are investigated. The research used methods of systems analysis, mathematical modeling, optimization, control theory, proccss theory and chemical technology. According to the research results, the structure of the automated control system of the hydrogen production proccss was studied, the regularities of the dynamics of adsorption processes with cyclic pressure change under different perturbations were studied and the application of the adaptive control system of the cyclic proccss of adsorption separation of gas mixture with hydrogen production was proposed.

Carbonate minerals play a very important role in nature, they represent some of the most diverse and common mineral species on the Planet. They are directly involved in the carbon dioxide (CO2) cycle acting as relatively stable long term chemical storage reservoirs, moderating both global warming trends and oceanaquatic chemistry through carbonate buffering systems. A range of synthetic metal carbonates have been synthesised for analysis under multiple experimental conditions, in order to study the variation in physical and chemical properties such as phase specificity, metal substitution, hydration/hydroxy carbonate formation under varying partial pressures of CO2 and thermal stability. Synthetic samples were characterised by a variety of instrumental analysis techniques in order to investigate chemical purity and phase specificity. Some of the techniques included, vibrational spectroscopy (IR/Raman), thermal analysis (TGA-MS) (thermal Raman), X-Ray diffraction (XRD) and electron microscopy (SEM-EDX). From the instrumental characterisation techniques, it was found that single phase smithsonite, hydrozincite, calcite and nesquehonite could successfully be synthesised under the conditions used. Minor impurities of other minerals and / or phases were found to form under specific chemical or physical conditions such as in the case of hydrozincite / simonkolleite if zinc chloride was used during hydrothermal synthesis.