Operação do sistema ibérico de gás natural: localização das fontes de abastecimento

Em consequência do acentuado crescimento da procura do gás natural, é essencial a organização de uma eficiente infra-estrutura de abastecimento de gás. O local certo para instalar as UFGs - Unidades de Fornecimento de Gás, assim como a afectação óptima dessas fontes às cargas de gás da rede, devem ser convenientemente planeados, de forma a minimizar os custos totais do sistema. Este estudo foi efectuado com o desenvolvimento de uma metodologia de cálculo baseada na aplicação do problema das P-medianas, resolvido pela abordagem Lagrangeana. A heurística Lagrangeana desenvolvida foi aplicada ao caso concreto da rede Ibérica primária de gás natural, modelizada em 65 nós de carga, ligados quer por gasodutos físicos quer por gasodutos virtuais. São apresentados os resultados computacionais gráficos que apoiam a decisão da escolha das UFGs, para um cenário previsível de evolução da procura do combustível até 2015.

Modelização do despacho económico de Gás Natural

Com as variações e instabilidade dos preços do petróleo, assim como as políticas europeias para adoção de estratégias para o desenvolvimento sustentável, têm levado à procura de forma crescente de novas tecnologias e fontes de energia alternativas. Neste contexto, tem-se assistido a políticas energéticas que estimulam o aumento da produção e a utilização do gás natural, visto que é considerado uma fonte de energia limpa. O crescimento do mercado do gás natural implica um reforço significativo das redes de transporte deste combustível, quer ao nível do armazenamento e fornecimento, quer ao nível dos gasodutos e da sua gestão. O investimento em gasodutos de transporte implica grandes investimentos, que poderiam não 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 gás natural acarreta custos elevados para os consumidores, tanto maiores quanto maior forem as quantidades de gás transacionadas e quanto maior for o percurso pelo gás natural percorrido. Assim assume especial importância a realização de um despacho de gás natural: quais as cargas que cada unidade de fornecimento de gás irá alimentar, qual a quantidade de gás natural que cada UFGs deve injetar na rede, qual o menor percurso possível para o fazer, o tipo de transporte que será utilizado? Estas questões são abordadas na presente dissertação, por forma a minimizar a função custo de transporte, diminuindo assim as perdas na rede de alta pressão e os custos de transporte que serão suportados pelos consumidores. A rede de testes adotada foi a rede nacional de transporte, constituída por 18 nós de consumos, e os tipos de transporte considerados, foram o transporte por gasoduto físico e o transporte através de gasoduto virtual – rotas de transporte rodoviário de gás natural liquefeito. Foram criados diversos cenários, baseados em períodos de inverno e verão, os diferentes cenários abrangeram de forma distinta as variáveis de forma a analisar os impactos que estas variáveis teriam no custo relativo ao transporte de gás natural. Para dar suporte ao modelo de despacho económico, foi desenvolvida uma aplicação computacional – Despacho_GN com o objetivo de despachar as quantidades de gás natural que cada UFG deveria injetar na rede, assim como apresentar os custos acumulados relativos ao transporte. Com o apoio desta aplicação foram testados diversos cenários, sendo apresentados os respectivos resultados. A metodologia elaborada para a criação de um despacho através da aplicação “Despacho_GN” demonstrou ser eficiente na obtenção das soluções, mostrando ser suficientemente rápida para realizar as simulações em poucos segundos. A dissertação proporciona uma contribuição para a exploração de problemas relacionados com o despacho de gás natural, e sugere perspectivas futuras de investigação e desenvolvimento.

Sistema Híbrido de Inferência Baseado em Análise de Componentes Principais e Redes Neurais Artificiais Aplicado a Plantas de Processamento de Gás Natural

Nowadays, where the market competition requires products with better quality and a constant search for cost savings and a better use of raw materials, the research for more efficient control strategies becomes vital. In Natural Gas Processin Units (NGPUs), as in the most chemical processes, the quality control is accomplished through their products composition. However, the chemical composition analysis has a long measurement time, even when performed by instruments such as gas chromatographs. This fact hinders the development of control strategies to provide a better process yield. The natural gas processing is one of the most important activities in the petroleum industry. The main economic product of a NGPU is the liquefied petroleum gas (LPG). The LPG is ideally composed by propane and butane, however, in practice, its composition has some contaminants, such as ethane and pentane. In this work is proposed an inferential system using neural networks to estimate the ethane and pentane mole fractions in LPG and the propane mole fraction in residual gas. The goal is to provide the values of these estimated variables in every minute using a single multilayer neural network, making it possibly to apply inferential control techniques in order to monitor the LPG quality and to reduce the propane loss in the process. To develop this work a NGPU was simulated in HYSYS R software, composed by two distillation collumns: deethanizer and debutanizer. The inference is performed through the process variables of the PID controllers present in the instrumentation of these columns. To reduce the complexity of the inferential neural network is used the statistical technique of principal component analysis to decrease the number of network inputs, thus forming a hybrid inferential system. It is also proposed in this work a simple strategy to correct the inferential system in real-time, based on measurements of the chromatographs which may exist in process under study

Matrizes poliméricas puras e modificadas para adsorção do gás sulfeto de hidrogênio

The underground natural gas found associated or not with oil is characterized by a mixture of hydrocarbons and residual components such as carbon dioxide (CO2), nitrogen gas (N2) and hydrogen sulfide (H2S), called contaminants. The H2S especially promotes itself as a contaminant of natural gas to be associated with corrosion of pipelines, to human toxicity and final applications of Natural Gas (NG). The sulfur present in the GN must be fully or partially removed in order to meet the market specifications, security, transport or further processing. There are distinct and varied methods of desulfurization of natural gas processing units used in Natural Gas (UPGN). In order to solve these problems have for example the caustic washing, absorption, the use of membranes and adsorption processes is costly and great expenditure of energy. Arises on such findings, the need for research to active processes of economic feasibility and efficiency. This work promoted the study of the adsorption of sulfide gas in polymer matrices hydrogen pure and modified. The substrates of Poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA) and sodium alginate (NaALG) were coated with vanadyl phosphate compounds (VOPO4.2H2O), vanadium pentoxide (V2O5), rhodamine B (C28H31N2O3Cl) and ions Co2+ and Cu2+, aiming to the adsorption of hydrogen sulfide gas (H2S). The adsorption tests were through a continuous flow of H2S in a column system (fixed bed reactor) adsorption on a laboratory scale. The techniques used to characterize the adsorbents were Infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), X-ray fluorescence (XRF), the X-ray diffraction (XRD) electron microscopy (SEM). Such work indicates, the results obtained, the adsorbents modified PMMA, PVC and NaALG have a significant adsorptive capacity. The matrix that stood out and had the best adsorption capacity, was to ALG modified Co2+ with a score of 12.79 mg H2S / g matrix

Estudo do desempenho de resinas poliméricas para remoção de H2S do gás natural

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 Agência Nacional do Petróleo 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

Estudo do desempenho de resinas poliméricas para remoção de H2S do gás natural

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 Agência Nacional do Petróleo 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

Modelagem e simulação de sistemas de geração de energia para o setor de petróleo e gás

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)