CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O uso de cilindros recheados com carbono ativado para armazenamento e transporte de gÃs natural (GN) a pressÃes moderadas (~3,5 MPa) e a temperatura ambiente (~298 K) tÃm sido estudados como uma potencial alternativa para o armazenamento de GN comprimido a altas pressÃes (~20 MPa). O presente trabalho fornece uma investigaÃÃo experimental de ciclos de carga e descarga de GN em um vaso de armazenamento de gÃs natural adsorvido (GNA) recheado com carbono ativado. à avaliado tambÃm o efeito da composiÃÃo do GN na capacidade de armazenamento. As propriedades de adsorÃÃo foram verificadas a partir de isotermas de cada componente do GN medidas em uma balanÃa de suspensÃo magnÃtica e comparadas com dados de adsorÃÃo medidos no vaso de armazenamento usando GN. As seletividades dos principais componentes do gÃs natural em relaÃÃo ao metano foram determinadas e a influencia da pressÃo nessa seletividade tambÃm foi observada. Apesar de o GN ser composto principalmente por metano (~90% em volume), foi observado que a adsorÃÃo preferencial pelos hidrocarbonetos mais pesados e CO2 deve ser levada em conta para a avaliaÃÃo do comportamento de sistemas GNA ao longo de vÃrios ciclos de carga e descarga. Foi estudado tambÃm para esse trabalho a separaÃÃo de CO2 de misturas de CO2/CH4, que à uma importante questÃo na purificaÃÃo do gÃs natural e biogÃs para aplicaÃÃo em geraÃÃo de energia. Dessa forma, dados de adsorÃÃo de mistura CO2/CH4 em carbono ativado a 293 K foram obtidos pelo mÃtodo volumÃtrico-cromatogrÃfico e comparados com a IAST (Teoria da SoluÃÃo Adsorvida Ideal) e com o modelo de Langmuir estendido (EL). AdsorÃÃo preferencial de CO2 foi observada para a composiÃÃo de mistura de CO2 maiores que 20% aproximadamente. A precisÃo das prediÃÃes foi menor do que a desejÃvel para uma aplicaÃÃo em projetos de engenharia. / The use of vessels filled with activated carbon to store and transport natural gas (NG) at moderate pressures (about 3.5 MPa) and ambient temperature (about 298 K) has been studied as a potential alternative to compressed natural gas storage at high pressures (ca. 20 MPa). The present study provides an experimental investigation of charge and discharge cycles of natural gas in a prototype storage vessel filled with activated carbon and analyses the effect of the gas composition on the adsorption capacity. The adsorption properties were evaluated by measuring isotherms for each component of NG in a magnetic suspension balance and compared with the isotherms measured in a storage vessel using NG. The selectivities of the main constituents of natural gas in relation to methane were determined and the influence of the pressure on the selectivity was also observed. Although NG is composed mainly of methane (ca. 90% vol.), our experimental results indicate that the preferential adsorption of the heavier hydrocarbons and CO2 should be properly taken into account for the evaluation of the behavior of adsorbed natural gas systems along several charge and discharge cycles. In an another context, the separation of CO2 from CO2-CH4 mixtures is an important issue in natural gas and biogas purification/upgrading for energy generation applications and it was also studied in this work. Thus, co-adsorption data of the binary mixture CO2/CH4 on activated carbon at 293 K was obtained by the volumetricchromatographic method and it was compared with the IAST (Ideal Adsorbed Solution Theory) and the Extended Langmuir (EL) predictions. Preferential adsorption of CO2 was observed for the CO2 mixture composition more than around 20%. The accuracy of predictions was less than desirable to an application engineer.

Orientador: Flávio Vasconcelos da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T21:00:26Z (GMT). No. of bitstreams: 1 Rodrigues_Sergio_M.pdf: 4024499 bytes, checksum: 621b50dee12f09a22c121b01b7c3340b (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foi utilizada uma série histórica de dados reais de danos sofridos na rede de distribuição de gás natural da concessionária Comgás, em sua área de concessão no estado de São Paulo abrangendo 177 municípios das regiões metropolitanas de São Paulo, Campinas, Baixada Santista e Vale do Paraíba. Com a análise desses dados foi observado que a ocorrência de danos na rede subterrânea de distribuição de gás natural é composta por harmônicas de diferentes frequências e amplitudes. Através da aplicação da transformada de Fourier a série histórica de dados de danos, identificou-se a presença de quatro harmônicas e seus respectivos períodos e magnitudes. De posse desses coeficientes de Fourier aplicou-se a eles a série de Fourier e construiu-se um modelo matemático que representou a função dano com um intervalo de confiança de 94% tornando assim possível prever sua intensidade no domínio do tempo / Abstract: This study used a real third party excavation damages time series data on a natural gas distribution network that belongs to Comgás in your concession area, Brazil, São Paulo state with 177 cities included in metropolitan areas as São Paulo, Campinas, Santos and Vale do Paraiba, demonstrates that this occurrence is droved by harmonic or cycled forces with different frequencies am magnitudes. Due to the application of Fourier transform at the historical damages time series data there was an identification of four harmonic forces and your periods and magnitudes. With this Fourier coefficients identified was applied to a Fourier series to model the third party damage function in time domain. This model gets a 94% of confidential interval and becomes able to prevent damages or time periods with more incidences of damages / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

This paper sheds light on the differences and similarities in natural gas trading at the National Balancing Point in the UK and the Henry Hub located in the US. For this, we analyze traders' expectations and implement a mechanical forecasting model that allows traders to predict future spot prices. Based on this, we compute the deviations between expected and realized spot prices and analyze possible reasons and dependencies with other market variables. Overall, the mechanical predictor performs well, but a small forecast error remains which can not be characterized by the explanatory variables included.

Please read the abstract (Synopsis) in the section 00front of this document / Dissertation (M Eng (Chemical Engineering))--University of Pretoria, 2007. / Chemical Engineering / MEng / unrestricted

An immediate reduction in global CO2 emissions could be accomplished by replacing coal- or oil-based energy sources with purified natural gas. The most important process involved in natural gas purification is the separation of CO2 from CH4, where Pressure Swing Adsorption (PSA) technology on porous materials has emerged as a less energy demanding technology. Among porous materials which are used or could potentially be used in PSA, Metal Organic Frameworks (MOFs) have attracted particular interest owing to their record-breaking surface areas, high-porosity, and high tunability. However, the discovery of optimal MOFs for use in adsorption-based CO2 separation processes is remarkably challenging, as millions of MOFs can potentially be constructed from virtually limitless combinations of inorganic and organic secondary building units. To overcome this combinatorial problem, this thesis aims to (1) identify important design features of MOFs for CO2/CH4 separation through the investigation of currently existing MOFs as well as the high throughput computational screening of a large database of MOFs, and to (2) develop efficient computational tools for aiding the discovery of new MOF materials. To validate the computational methods and models used in this thesis, the first work of this thesis presents the computational modeling of CO2 adsorption on an experimental CuBDPMe MOF using grand canonical Monte Carlo simulations and density functional theory. The simulated CO2 adsorption isotherms are in good agreement with experiment, which confirms the accuracy of the models used in our simulations throughout this thesis. The second work of this thesis investigates the performance of an experimental MIL-47 MOF and its seven functionalized derivatives in the context of natural gas purification, and compares their performance with that of other well-known MOFs and commercially used adsorbents. The computational results show that introducing polar non-bulky functional groups on MIL-47 leads to an enhancement in its performance, and the comparison suggests that MIL-47-NO2 could be a possible candidate as a solid sorbent for natural gas purification. This study is followed by the compactional study of water effects on natural gas purification using MOFs, as traces of water is present in natural gas under pipeline specifications. From the study, it is found that water has a marginal effect on natural gas purification in hydrophobic MOFs under pipeline specifications. Following the aforementioned studies, a database of 324,500 hypothetical MOFs is screened for their performance in natural gas purification using the general protocol defined in this thesis. From the study, we identify 'hit' materials for targeted synthesis, and investigate the structure-property relationships with the intent of finding important MOF design features relevant to natural gas purification. We show that layered sheets consisting of poly-aromatic molecules separated by a perpendicular distance of roughly 7 Å are an important structural-chemical feature that leads to strong adsorption of CO2. Following the screening study, we develop efficient computational tools for the recognition of high-preforming MOFs for methane purification using Machine Learning techniques. A training set of 32,500 MOF structures was used to calibrate support vector machines (SVMs) classifiers that incorporate simple geometrical features including pore size, void fraction and surface area. The SVM machine learning classifiers can be used as a filtering tool when screening large databases. The SVM classifiers were tested on ~290,000 MOFs that were not part of the training set and could correctly identify up to 70% of high-performing MOFs while only flagging a fraction of the MOFs for more rigorous screening. As a complement to this study, we present ML classifier models for CO2/CH4 separation parameters that incorporate separately the Voronoi hologram and AP-RDF descriptors, and we compare their performance with the classifiers composed of simple geometrical descriptors. From the comparison, it is found that including AP-RDF and Voronoi hologram descriptors into the classifiers improves the performance of classifiers by 20% in capturing high-performing MOFs. Finally, from the screening data, we develop a novel chemiformatics tool, MOFFinder, for aiding in the discovery of new MOFs for CO2 scrubbing from natural gas. It has a user-friendly graphical interface to promote easy exploration of over 300,000 hypothetical MOFs. It enables synthetic chemists to find MOFs of interest by searching the database for Secondary Building Units (SBUs), geometric features, functional groups and adsorption properties. MOFFinder provides, for the first time the substructure/similarity query of porous materials for users and is publicly available on titan.chem.uottawa.ca/moffinger.

This thesis presents the results of an investigation of the differences in combustion between gasoline and natural gas in a spark-ignition engine. Combustion development is influenced by calorific value, specific heat, flame speed and the gaseous or liquid state of the fuel. Simple simulation programs were set up to investigate the effects of low flame speed and higher specific heat of the fuel-air mixture. Actual performance was measured on a single cylinder test engine using ionization probes as flame detectors and a pressure pick-up. The experimental results show that longer ignition delay and limited flame speed at high pressure and temperature are the main reasons for' the power loss of natural gas at high engine speed; this is in addition to the basic loss due to the replacement of air by gaseous fuel in the cylinder. From calculations, it was learned that specific heat and dissociation differences had little effect on power. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The aim of the thesis is to describe structural changes in the U.S. natural gas industry after implementation of hydraulic fracturing method which exploit natural gas from shale. In order to provide a complex description; environmental, market impacts and political interests are taken into consideration. Consequently, cluster analysis looks for a change in relations among various factors arising on the market. Tested periods are carefully chosen according to market events and results of statistical tests. One may conclude, it is a complexity of market, technology improvement and government behaviour which influence natural gas industry in USA.

AN ABSTRACT OF THE DISSERTATION OFSUMAN SAURABH, for the Doctor of Philosophy degree in Engineering Science, presented on August 30, 2019, at Southern Illinois University Carbondale.TITLE: GEOMECHANICAL STATE OF ROCKS WITH DEPLETION IN UNCONVENTIONAL COALBED METHANE RESERVOIRSMAJOR PROFESSOR: Dr. Satya HarpalaniOne of the major reservoir types in the class of unconventional reservoirs is coalbed methane. Researchers have treated these reservoirs as isotropic when modeling stress and permeability, that is, mechanical properties in all directions are same. Furthermore, coal is a highly sorptive and stress- sensitive rock. The focus of this dissertation is to characterize the geomechanical aspects of these reservoirs, strain, stresses, effective stress and, using the information, establish the dynamic flow/permeability behavior with continued depletion. Several aspects of the study presented in this dissertation can be easily extended to shale gas reservoirs. The study started with mechanical characterization and measurement of anisotropy using experimental and modeling work, and evaluation of how the sorptive nature of coal can affect the anisotropy. An attempt was also made to characterize the variation in anisotropy with depletion. The results revealed that the coals tested were orthotropic in nature, but could be approximated as transversely isotropic, that is, the mechanical properties were isotropic in the horizontal plane, but significantly different in vertical direction. Mechanical characterization of coal was followed by flow modeling. Stress data was used to characterize the changes in permeability with depletion. This was achieved by plotting stress path followed by coal during depletion. The model developed was used to successfully predict the permeability variation in coal with depletion for elastic deformations. As expected, the developed model failed to predict the permeability variation resulting from inelastic deformation given that it was based on elastic constitutive equations. Hence, the next logical step was to develop a generalized permeability model, which would be valid for both elastic and inelastic deformations. Investigation of the causes of coal failure due to anisotropic stress redistribution during depletion was also carried out as a part of this study. It was found that highly sorptive rocks experience severe loss in horizontal stresses with depletion and, if their mechanical strength is not adequate to support the anisotropic stress redistribution, rock failure can result. In order to develop a generalized permeability model based on stress data, stress paths for three different coal types were established and the corresponding changes in permeability were studied. Stress path plotted in an octahedral mean stress versus octahedral shear stress plane provided a signal for changes in the permeability for both elastic as well as inelastic deformations. This signal was used to develop a mechanistic model for permeability modeling, based on stress redistribution in rocks during depletion. The model was able to successfully predict the permeability variation for all three coal types. Finally, since coal is highly stress- sensitive, changes in effective stresses were found to be the dictating factor for deformations, changes in permeability and possible failure with depletion. Hence, the next step was to develop an effective stress law for sorptive and transversely isotropic rocks. For development of an effective stress law for stress sensitive, transversely isotropic rocks, previously established constitutive equations were used to formulate a new analytical model. The model was then used to study changes in the variation of Biot’s coefficient of these rocks. It was found that Biot’s coefficient, typically less than one, can take values larger than one for these rocks, and their values also change with depletion. The study provides a methodology which can be used to estimate the Biot’s coefficient of any rock. As a final step, preliminary work was carried out on the problem of under-performing coal reservoirs in the San Juan basin, where coal is extremely tight with very low permeability. An extension of the work presented in this dissertation is to use the geomechanical characterization techniques to unlock these reservoirs and improve their performance. The experimental data collected during this preliminary study is included in the last chapter of the dissertation.

This dissertation addresses the rational design of intrinsically microporous solutionprocessable polyimides and ladder polymers for highly permeable and highly selective gas transport in cornerstone applications of membrane-based gas separation – that is, air enrichment, hydrogen recovery and natural gas sweetening. By virtue of rigid and contorted chains that pack inefficiently in the solid state, polymers of intrinsic microporosity (PIMs) have the potential to unite the solution-processability, mechanical flexibility and organic tunability of commercially relevant polymers with the microporosity characteristics of porous crystalline materials. The performance enhancements of PIMs over conventional low-free-volume polymers have been primarily permeability-driven, compromising the selectivity essential to commercial viability. An approach to unite high permeability with high selectivity for performance transcending the state-of-the-art in air and hydrogen separations was demonstrated via a fused-ring integration of a three-dimensional, shape persistent triptycene moiety optimally substituted with short, branched isopropyl chains at the 9,10-bridgeheads into a highly inflexible backbone. The resulting polymers exhibited selectivities (i.e., O2/N2, H2/N2, H2/CH4) similar to or higher than commercial materials matched with permeabilities up to three hundred times higher. However, the intra-chain rigidity central to such conventional PIM-design principles was not a singular solution to suppression of CO2-induced plasticization in CO2/CH4 mixedgas separations. Plasticization diminishes the sieving capacity of the membrane, resulting in costly hydrocarbon losses that have significantly limited the commercialization of new polymers. Unexpectedly, the most permeable and selective PIMs designed for air and hydrogen separations strongly plasticized in 50:50 CO2/CH4 mixtures, enduring up to three-fold increases in mixed-gas CH4 permeability by 30 bar and strong drops in selectivity. Instead, a paradigm shift emphasizing inter-chain rigidity was demonstrated for the PIM-type polyimides via introduction of a flexible diamine functionalized with hydroxyl groups. Intra-chain flexibility may permit short-range coplanarization of backbone segments which facilitates inter-chain interactions likely comprising charge transfer complexes over the N-phenyl imide bond and hydrogen bonding. Relative to commercial cellulose acetate membranes at a representative 10 bar CO2 partial pressure, the resulting polyimide exhibited two-fold increases in mixed-gas CO2/CH4 selectivity (~50) concurrent with nearly 10-fold higher CO2 gas permeability. Similar design principles were drawn for ladder polymers.

This thesis deals with storage of natural gas in hydrates, forming of hydrate, its transportation and storage. Within the calculation part, three hydrate forming reactors are compared. According to the paramters used in the calculations, a reactor is designed. Basic drawing documentation is also available. The final calculations focus on the nominal evaporation of the storage tank.