Ihwg-��nir: A Miniaturised Near-infrared Gas Sensor Based On Substrate-integrated Hollow Waveguides Coupled To A Micro-nir-spectrophotometer.

A miniaturised gas analyser is described and evaluated based on the use of a substrate-integrated hollow waveguide (iHWG) coupled to a microsized near-infrared spectrophotometer comprising a linear variable filter and an array of InGaAs detectors. This gas sensing system was applied to analyse surrogate samples of natural fuel gas containing methane, ethane, propane and butane, quantified by using multivariate regression models based on partial least square (PLS) algorithms and Savitzky-Golay 1(st) derivative data preprocessing. The external validation of the obtained models reveals root mean square errors of prediction of 0.37, 0.36, 0.67 and 0.37% (v/v), for methane, ethane, propane and butane, respectively. The developed sensing system provides particularly rapid response times upon composition changes of the gaseous sample (approximately 2 s) due the minute volume of the iHWG-based measurement cell. The sensing system developed in this study is fully portable with a hand-held sized analyser footprint, and thus ideally suited for field analysis. Last but not least, the obtained results corroborate the potential of NIR-iHWG analysers for monitoring the quality of natural gas and petrochemical gaseous products.

Optimisation of environmental gas cleaning routes for solid wastes cogeneration systems. Part II - Analysis of waste incineration combined gas/steam cycle

In the first paper of this paper (Part I), conditions were presented for the gas cleaning technological route for environomic optimisation of a cogeneration system based in a thermal cycle with municipal solid waste incineration. In this second part, an environomic analysis is presented of a cogeneration system comprising a combined cycle composed of a gas cycle burning natural gas with a heat recovery steam generator with no supplementary burning and a steam cycle burning municipal solid wastes (MSW) to which will be added a pure back pressure steam turbine (another one) of pure condensation. This analysis aims to select, concerning some scenarios, the best atmospheric pollutant emission control routes (rc) according to the investment cost minimisation, operation and social damage criteria. In this study, a comparison is also performed with the results obtained in the Case Study presented in Part I. (c) 2007 Elsevier Ltd. All rights reserved.

Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any n x 1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters. (C) 2007 Elsevier Ltd. All rights reserved.

Factors controlling the origin of gas in Australian Bowen Basin coals

Open system pyrolysis (heating rate 10 degrees C/min) of coal maturity (vitrinite reflectance, VR) sequence (0.5%, 0.8% and 1.4% VR) demonstrates that there are two stages of thermogenic methane generation from Bowen Basin coals. The first and major stage shows a steady increase in methane generation maximising at 570 degrees C, corresponding to a VR of 2-2.5%. This is followed by a less intense methane generation which has not as yet maximised by 800 degrees C (equivalent to VR of 5%). Heavier (C2+) hydrocarbons are generated up to 570 degrees C after which only the C-1 (CH4, CO and CO2) gases are produced. The main phase of heavy hydrocarbon generation occurs between 420 and 510 degrees C. Over this temperature range,methane generation accounts for only a minor component, whereas the wet gases (C-2-C-5) are either in equal abundance or are more abundant by a factor of two than the liquid hydrocarbons. The yields of non-hydrocarbon gases CO2 and CO are greater then methane during the early stages of gas generation from an immature coal, subordinate to methane during the main phase of methane generation after which they are again dominant. Compositional data for desorbed and produced coal seam gases from the Bowen show that CO2 and wet gases are a minor component. This discrepancy between the proportion of wet gas components produced during open system pyrolysis and that observed in naturally matured coals may be the result of preferential migration of wet gas components, by dilution of methane generated during secondary cracking of bitumen, or kinetic effects associated with different activations for production of individual hydrocarbon gases. Extrapolation of results of artificial pyrolysis of the main organic components in coal to geological significant heating rates suggests that isotopically light methane to delta(13)C of -50 parts per thousand can be generated. Carbon isotope depletions in C-13 are further enhanced, however, as a result of trapping of gases over selected rank levels (instantaneous generation) which is a probable explanation for the range of delta(13)C values we have recorded in methane desorbed from Bowen Basin coals (-51 +/- 9 parts per thousand). Pervasive carbonate-rich veins in Bowen Basin coals are the product of magmatism-related hydrothermal activity. Furthermore, the pyrolysis results suggest an additional organic carbon source front CO2 released at any stage during the maturation history could mix in varying proportions with CO2 from the other sources. This interpretation is supported by C and O isotopic ratios, of carbonates that indicate mixing between magmatic and meteoric fluids. Also, the steep slope of the C and O isotope correlation trend suggests that the carbonates were deposited over a very narrow temperature interval basin-wide, or at relatively high temperatures (i.e., greater than 150 degrees C) where mineral-fluid oxygen isotope fractionations are small. These temperatures are high enough for catagenic production of methane and higher hydrocarbons from the coal and coal-derived bitumen. The results suggests that a combination of thermogenic generation of methane and thermodynamic processes associated with CH4/CO2 equilibria are the two most important factors that control the primary isotope and molecular composition of coal seam gases in the Bowen Basin. Biological process are regionally subordinate but may be locally significant. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

An heuristic approach for optimal location of gas supply units in transportation system

The best places to locate the Gas Supply Units (GSUs) on a natural gas systems and their optimal allocation to loads are the key factors to organize an efficient upstream gas infrastructure. The number of GSUs and their optimal location in a gas network is a decision problem that can be formulated as a linear programming problem. Our emphasis is on the formulation and use of a suitable location model, reflecting real-world operations and constraints of a natural gas system. This paper presents a heuristic model, based on lagrangean approach, developed for finding the optimal GSUs location on a natural gas network, minimizing expenses and maximizing throughput and security of supply.The location model is applied to the Iberian high pressure natural gas network, a system modelised with 65 demand nodes. These nodes are linked by physical and virtual pipelines ��� road trucks with gas in liquefied form. The location model result shows the best places to locate, with the optimal demand allocation and the most economical gas transport mode: by pipeline or by road truck.

Redes de distribui����o de g��s natural: projeto e desenvolvimento

Atualmente o g��s natural �� a principal fonte de energia utilizada pela maioria dos europeus nos setores dom��stico, terci��rio e industrial. �� considerado a alternativa energ��tica do futuro e a mais ecologicamente correta de que podemos dispor, numa escala compat��vel com as elevadas necessidades energ��ticas da Humanidade a n��vel global. Aliado a estes factos, surgem cada vez mais regras de boa pr��tica, normas e legisla����o, nomeadamente especifica����es t��cnicas de forma a regular o setor e dotar as entidades intervenientes na conce����o e controlo de uma instala����o de rede de g��s, de um conhecimento mais detalhado e atualizado sobre esta mat��ria. Esta disserta����o pretende assim contribuir para a melhoria e moderniza����o do desempenho de todos os que exercem fun����es neste setor, com vista ao aperfei��oamento da qualidade e utilidade dos seus servi��os. Este trabalho re��ne o conjunto de informa����o t��cnica presente na legisla����o e normas de forma a preencher a eventual falha do conhecimento neste ramo por parte destes profissionais dotando-os de um conhecimento mais aprofundado, de modo a que possam executar corretamente e de forma eficaz o seu trabalho. Por outro lado, esta disserta����o tem como objetivo o projeto e desenvolvimento de uma rede de distribui����o de g��s natural aplicado a tr��s redes concretas: rede de distribui����o, edif��cio e moradia. A conce����o do projeto de instala����o de g��s inicia-se com a recolha de informa����o, seguindo-se o desenvolvimento do estudo do tra��ado. Assim, est��o reunidas as condi����es para dimensionar e providenciar a escolha de materiais mais adequados para a execu����o da obra. A metodologia de dimensionamento adotada teve por base a equa����o dos gases perfeitos e a f��rmula de Renouard simplificada, encontrando-se implementada numa folha de c��lculo. Esta ferramenta de c��lculo aliada �� metodologia permite realizar de forma expedita o correto dimensionamento de uma rede de g��s, bem como apurar se a velocidade de escoamento se encontra em conformidade com o definido no projeto.

Modeliza����o do despacho econ��mico de G��s Natural

Com as varia����es e instabilidade dos pre��os do petr��leo, assim como as pol��ticas europeias para ado����o de estrat��gias para o desenvolvimento sustent��vel, t��m levado �� procura de forma crescente de novas tecnologias e fontes de energia alternativas. Neste contexto, tem-se assistido a pol��ticas energ��ticas que estimulam o aumento da produ����o e a utiliza����o do g��s natural, visto que �� considerado uma fonte de energia limpa. O crescimento do mercado do g��s natural implica um refor��o significativo das redes de transporte deste combust��vel, quer ao n��vel do armazenamento e fornecimento, quer ao n��vel dos gasodutos e da sua gest��o. O investimento em gasodutos de transporte implica grandes investimentos, que poderiam n��o ser remunerados da forma esperada, sendo um dos motivos para que exista em Portugal cinco distritos se veem privados deste tipo de infraestruturas. O transporte de g��s natural acarreta custos elevados para os consumidores, tanto maiores quanto maior forem as quantidades de g��s transacionadas e quanto maior for o percurso pelo g��s natural percorrido. Assim assume especial import��ncia a realiza����o de um despacho de g��s natural: quais as cargas que cada unidade de fornecimento de g��s ir�� alimentar, qual a quantidade de g��s natural que cada UFGs deve injetar na rede, qual o menor percurso poss��vel para o fazer, o tipo de transporte que ser�� utilizado? Estas quest��es s��o abordadas na presente disserta����o, por forma a minimizar a fun����o custo de transporte, diminuindo assim as perdas na rede de alta press��o e os custos de transporte que ser��o suportados pelos consumidores. A rede de testes adotada foi a rede nacional de transporte, constitu��da por 18 n��s de consumos, e os tipos de transporte considerados, foram o transporte por gasoduto f��sico e o transporte atrav��s de gasoduto virtual ��� rotas de transporte rodovi��rio de g��s natural liquefeito. Foram criados diversos cen��rios, baseados em per��odos de inverno e ver��o, os diferentes cen��rios abrangeram de forma distinta as vari��veis de forma a analisar os impactos que estas vari��veis teriam no custo relativo ao transporte de g��s natural. Para dar suporte ao modelo de despacho econ��mico, foi desenvolvida uma aplica����o computacional ��� Despacho_GN com o objetivo de despachar as quantidades de g��s natural que cada UFG deveria injetar na rede, assim como apresentar os custos acumulados relativos ao transporte. Com o apoio desta aplica����o foram testados diversos cen��rios, sendo apresentados os respectivos resultados. A metodologia elaborada para a cria����o de um despacho atrav��s da aplica����o ���Despacho_GN��� demonstrou ser eficiente na obten����o das solu����es, mostrando ser suficientemente r��pida para realizar as simula����es em poucos segundos. A disserta����o proporciona uma contribui����o para a explora����o de problemas relacionados com o despacho de g��s natural, e sugere perspectivas futuras de investiga����o e desenvolvimento.

Otimiza����o energ��tica �� sec����o das malhas

A presente disserta����o realizada na empresa Continental-Ind��stria T��xtil do Ave, S.A., teve como objetivo a otimiza����o energ��tica da sec����o das malhas. Esta sec����o divide-se em duas ��reas, a tricotagem e a ramulagem. Os artigos produzidos diferem no seu peso espec��fico, composi����o e condi����es de opera����o, sendo os artigos A, B e C compostos por poli��ster e termofixados a 190��C e os artigos D e E compostos por poli��ster e algod��o, com uma temperatura de opera����o de 205��C. Numa primeira etapa estudou-se o funcionamento da m��quina de termofixa����o ��� a r��mula ��� que opera em trabalho cont��nuo a 40 m/min. Esta m��quina tem incorporado um permutador de calor, que aquece o ar fresco de entrada com os gases de exaust��o das estufas. Posteriormente efetuou-se o levantamento energ��tico de cada artigo, para as ��reas de tricotagem e ramulagem. Verificou-se que os artigos D e E, pela sua constitui����o, s��o os que apresentam um consumo espec��fico superior, em tep/ton. Entre as v��rias utilidades consumidas (g��s natural, eletricidade e ar comprimido) o g��s natural representa mais de 50% do consumo de energia total necess��rio para a produ����o de cada artigo. Ap��s a completa an��lise aos consumos energ��ticos da r��mula, foram realizados ensaios de otimiza����o, tendo-se conclu��do que a diminui����o do caudal de exaust��o pode atingir valores de poupan��a anual de g��s natural na ordem dos 3.000 ���. Com o objetivo de avaliar o consumo de g��s natural, n��o sendo poss��vel a realiza����o experimental, foram feitas simula����es com base em altera����es na corrente de entrada de ar fresco no permutador. Foi tamb��m estudada a possibilidade de isolamento e revestimento t��rmico da conduta exterior, projetada para o reaproveitamento do ar dos compressores, tendo-se obtido um or��amento de 2.500 ���. Admitindo-se uma gama de temperaturas entre os 40��C e os 60��C, com um caudal de insufla����o de 30%, obteve-se um payback entre os 0,97 e os 3,28 anos. Numa segunda fase admitiu-se uma temperatura m��dia de 50��C, aumentando o caudal de insufla����o at�� 100%. O per��odo de retorno obtido variou entre os 0,33 e os 1,38 anos, podendo as poupan��as anuais atingirem os 7.600 ���.

Molecular simulation of gas adsorption equilibria in nanoporous materials

This work is divided into two distinct parts. The first part consists of the study of the metal organic framework UiO-66Zr, where the aim was to determine the force field that best describes the adsorption equilibrium properties of two different gases, methane and carbon dioxide. The other part of the work focuses on the study of the single wall carbon nanotube topology for ethane adsorption; the aim was to simplify as much as possible the solid-fluid force field model to increase the computational efficiency of the Monte Carlo simulations. The choice of both adsorbents relies on their potential use in adsorption processes, such as the capture and storage of carbon dioxide, natural gas storage, separation of components of biogas, and olefin/paraffin separations. The adsorption studies on the two porous materials were performed by molecular simulation using the grand canonical Monte Carlo (��,V,T) method, over the temperature range of 298-343 K and pressure range 0.06-70 bar. The calibration curves of pressure and density as a function of chemical potential and temperature for the three adsorbates under study, were obtained Monte Carlo simulation in the canonical ensemble (N,V,T); polynomial fit and interpolation of the obtained data allowed to determine the pressure and gas density at any chemical potential. The adsorption equilibria of methane and carbon dioxide in UiO-66Zr were simulated and compared with the experimental data obtained by Jasmina H. Cavka et al. The results show that the best force field for both gases is a chargeless united-atom force field based on the TraPPE model. Using this validated force field it was possible to estimate the isosteric heats of adsorption and the Henry constants. In the Grand-Canonical Monte Carlo simulations of carbon nanotubes, we conclude that the fastest type of run is obtained with a force field that approximates the nanotube as a smooth cylinder; this approximation gives execution times that are 1.6 times faster than the typical atomistic runs.

Development of new membranes based on ionic liquid materials for gas separation

In the field of energy, natural gas is an essential bridge to a clean, low carbon, renewable energy era. However, natural gas processing and transportation regulation require the removal of contaminant compounds such as carbon dioxide (CO2). Regarding clean air, the increasing atmospheric concentrations of greenhouse gases, specifically CO2, is of particular concern. Therefore, new costeffective, high performance technologies for carbon capture have been researched and the design of materials with the ability to efficiently separate CO2 from other gases is of vital importance.(...)

A structured inventory of spiders (Arachnida, Araneae) in natural and artificial forest gaps at Porto Urucu, Western Brazilian Amazonia

A preliminary survey of the spider fauna in natural and artificial forest gap formations at ��Porto Urucu��, a petroleum/natural gas production facility in the Urucu river basin, Coari, Amazonas, Brazil is presented. Sampling was conducted both occasionally and using a protocol composed of a suite of techniques: beating trays (32 samples), nocturnal manual samplings (48), sweeping nets (16), Winkler extractors (24), and pitfall traps (120). A total of 4201 spiders, belonging to 43 families and 393 morphospecies, were collected during the dry season, in July, 2003. Excluding the occasional samples, the observed richness was 357 species. In a performance test of seven species richness estimators, the Incidence Based Coverage Estimator (ICE) was the best fit estimator, with 639 estimated species. To evaluate differences in species richness associated with natural and artificial gaps, samples from between the center of the gaps up to 300 meters inside the adjacent forest matrix were compared through the inspection of the confidence intervals of individual-based rarefaction curves for each treatment. The observed species richness was significantly higher in natural gaps combined with adjacent forest than in the artificial gaps combined with adjacent forest. Moreover, a community similarity analysis between the fauna collected under both treatments demonstrated that there were considerable differences in species composition. The significantly higher abundance of Lycosidae in artificial gap forest is explained by the presence of herbaceous vegetation in the gaps themselves. Ctenidae was significantly more abundant in the natural gap forest, probable due to the increase of shelter availability provided by the fallen trees in the gaps themselves. Both families are identified as potential indicators of environmental change related to the establishment or recovery of artificial gaps in the study area.

2007 Greenhouse Gas Emissions from Selected Iowa Source Categories

The Department���s 2007 Greenhouse Gas Inventory is a refinement of previous statewide inventories. It is a bottom-up inventory of two sectors ��� fossil fuel combustion at federally-recognized major sources of air pollution and fossil fuel combustion and ethanol fermentation at dry mill ethanol plants. This is the first bottomup greenhouse gas inventory conducted for Iowa and the first bottom-up greenhouse gas inventory of ethanol plants in the nation that the Department is aware of. In a bottom-up inventory, facility-specific activity data is used to calculate emissions. In a top-down inventory, aggregate activity data is used to calculate emissions. For example, this bottom-up inventory calculates greenhouse gas emissions from the fossil fuel combustion at each individual facility instead of using the total amount of fossil fuel combusted state-wide, which would be a top-down inventory method. The advantage to a bottom-up inventory is that the calculations are more accurate than a top-down inventory. However, because the two methods differ, the results from a bottom-up inventory are not directly comparable to a top-down inventory.

Petr��leo y gas en ��frica: viejas realidades, nuevos escenarios

[cat] En els ��ltims temps es parla molt del nou paper dels hidrocarburs d'��frica, fins i tot s'al��ludeix a un oil rush o a un african oil scramble , que inevitablement desembocar�� en una confrontaci�� bipolar entre la Xina i els Estats Units, pel control de les reserves de petroli del subs��l del continent afric��. Aix��, el prop��sit d'aquest text ��s, en primer lloc, realitzar una an��lisi descriptiva que ajudi a valorar la hip��tesi d'aquest african oil scramble. A continuaci��n, amb les dades obtingudes, es discutir�� sobre la possibilitat de que aquest fenomen desemboqui en un escenari de confrontaci�� xinoamericana. Aquesta especulaci�� ens dur�� a concloure que hi ha suficients indicis per a argumentar que el joc petrol��fer afric�� podria desenvolupar-se en un escenari marcat per la multilateralitat.

Petr��leo y gas en ��frica: viejas realidades, nuevos escenarios

[cat] En els ��ltims temps es parla molt del nou paper dels hidrocarburs d'��frica, fins i tot s'al��ludeix a un oil rush o a un african oil scramble , que inevitablement desembocar�� en una confrontaci�� bipolar entre la Xina i els Estats Units, pel control de les reserves de petroli del subs��l del continent afric��. Aix��, el prop��sit d'aquest text ��s, en primer lloc, realitzar una an��lisi descriptiva que ajudi a valorar la hip��tesi d'aquest african oil scramble. A continuaci��n, amb les dades obtingudes, es discutir�� sobre la possibilitat de que aquest fenomen desemboqui en un escenari de confrontaci�� xinoamericana. Aquesta especulaci�� ens dur�� a concloure que hi ha suficients indicis per a argumentar que el joc petrol��fer afric�� podria desenvolupar-se en un escenari marcat per la multilateralitat.

Estudo do nitrog��nio na combust��o do g��s natural

Nitrogen content in natural gas was studied in experimental and computational investigations to identify its influence on the emission level of exhaust gases from combustion facilities. Changes in natural gas composition with different N2 concentrations may result from introducing a new source gas into the system. An industrial burner fired at 75 kW, housed in a laboratory-scale furnace, was employed for runs where the natural gas/N2 proportion was varied. The exhaust and in-furnace measurements of temperature and gas concentrations were performed for different combustion scenarios, varying N2 content from 1-10 %v. Results have shown that the contamination of natural gas with nitrogen reduced the peak flame temperature, the concentration of unstable species, the NO X emission level and the heat transfer rate to the furnace walls, resulting from the recombination reactions.