- Email: [email protected]
00980 The thermal and mechanical behaviour of structural steel piping systems
03 Gaseous fuels (transport, storage) The production and the depletion of mineral resources, and especially oil and fossil fuels, have been the objects of extensive predictive modelling. These predictions are often derived from Hubbert's model, which is based on the fitting of the experimental data to a symmetric, bell-shaped curve. Although this model describes several historical cases, in particular, crude oil production in the lower 48 US states, not all theoretical models for the 'mineral economy' are based on symmetric curves. Also, not much attention has been dedicated so far to the mechanisms that lead to such a behaviour. In particular, scarce attention has been dedicated to the factors that may make the production curve asymmetric, e.g. a decline in production more abrupt than the growth. In the present paper, the author uses a stochastic model to examine factors affecting these phenomena. The results of the simulations indicate that the production curves of a non-renewable resource may be asymmetric in dependence on factors such as the search strategy or the presence of technologicai improvements. Considering worldwide oil production, the simulations indicate that the after-peak downward slope might turn out to be considerably steeper than the upward slope, something that could have unpleasant effects on the economy.
Derived liquid fuels 05/00976 A comparative experimental study on the liquefaction of wood Zhong, C. and Wei, X. Energy, 2004, 29, (11), 1731-1741. Aqueous liquefaction of Cunninghamia lanceolata, Fraxinus mandshurlea, Pinus massoniana Lamb. and Populus tomentosa Carr. was carried out in an autoclave in the reaction temperature range of 553.15-633.15 K, where both non-catalytic and catalytic liquefaction were performed. The experimental results show that the lignin content has a large effect on the yield of liquefaction products in the non-catalytic liquefaction. The addition of K2CO3 as a catalyst can significantly reduce the residue yield for all the woods tested, while its effect on the heavy oil yield becomes weaker with decreasing amounts of lignin. The present study shows that a heavy oil yield of 30% coupled with a residue yield of less than 10% can be obtained for all the wood samples tested in the catalytic liquefaction.
05100977 Towards sustainable production and use of charcoal in Kenya: exploring the potential in life cycle management approach Kituyi, E. Journal of Cleaner Production, 2004, 12, (8-10), 1047-1057. The study seeks to demonstrate the potential role that industrial ecology could play towards energy poverty reduction and environmental conservation in Kenya through sustainable charcoal production and consumption. This is achieved through an exploration of the application of the life cycle management (LCM) concept that identifies various opportunities for technological intervention for energy and environmental conservation and reduction of material and energy losses. It also identifies opportunities for income generation at various stages of the product's life cycle; an aspect critical in poverty reduction in developing countries. The study finds that applying LCM in the charcoal trade in Kenya can deliver social, economic and environmental benefits to developing country communities and should, therefore, be promoted. However, appropriate legal, policy and institutional frameworks must exist in these countries for this to occur.
03
GASEOUS FUELS Sources, properties, recovery, treatment
05•00978 Effect of low pH on the activity of hydrogen utilizing methanogen in bio-hydrogen process Kim, In. S. et al. International Journal of Hydrogen Energy, 2004, 29, (11), 1133 1140. The pH is one of the most important parameters for producing hydrogen in biological processes. The major effect of low pH is the inhibition of the methanogenie activity in anaerobic biological processes for the production of hydrogen and, in general, it is considered that a pH below 5 can inhibit the methanogenic activity. In a semi-continuous reactor for the production of hydrogen, the pH was maintained at 4.5 d=0.2 by fixing the influent alkalinity to 1000 mg/l
as CaCO3. The primary fermentation product in this pH range was butyrate. The rate of hydrogen production stabilized at 35:55 ml/g Glu-day after 35 days. The yield efficiency of hydrogen was relatively low due to the methanogenic activity. The methanogenic activity originated from the hydrogen utilizing methanogen, and was inhibited by the addition of nitrate. At pH 4.3, the butyrate type of fermentation was changed to the butanol type and, simultaneously, the production of hydrogen stopped.
05100979 Oxidative dehydrogenation of ethane on Tecontaining MoVNbO catalysts L6pez Nieto, J. M. et al. Catalysis Today, 2004, 91 92, 241 245. Ethylene has selectively been obtained during the oxidative dehydrogenation of ethane on a Mo-V-Te-Nb-O mixed oxide catalyst. The catalyst was prepared hydrothermally and heat-treated at 600°C for 2 h in a nitrogen stream. For comparison, undoped and Te-doped Mo-VNb-O catalysts and Mo-V-Te-O and Mo-Te-Nb-O mixed oxides have also been prepared. The catalytic performance of the Mo-V-Nb-Te-O mixed oxide catalyst cannot be explained by the incorporation of Te on the surface of a Mo-V-Nb-O mixed oxide but by the presence of an orthorhombic TezM20057 (M = Mo, V, Nb) crystalline phase. The role of tellurium in these catalysts is also discussed.
05100980 The thermal and mechanical behaviour of structural steel piping systems Fonseca, E. M. M. et al. International Journal of Pressure Vessels and Piping, 2005, 82, (2), 145-153. The temperature, the deformation and the stress field in thermomechanical problems play a very important role in engineering applications. This paper presents a finite element algorithm developed to perform the thermal and mechanical analysis of structural steel piping systems subjected to elevated temperatures. The new pipe element with 22 degrees of freedom has a displacement field that results from the superposition of a beam displacement, with the displacement field associated with the section distortion. Having determined the temperature field, the consequent thermal displacement produced in the piping systems due to the thermal variation can be calculated. The temperature rise produces thermal expansion and a consequent increase of pipe length in the structural elements. For small values of the ratio of the pipe thickness to mean radius, the thermal behaviour can be calculated with adequate precision using a onedimensional mesh approach, with thermal boundary conditions of an axisymmetric type across the pipe section. With this condition, several case studies of piping systems subjected to elevated temperatures and mechanical loads are presented and compared with corresponding results from commercial finite element codes. The main advantage of this formulation is associated with reduced time for mesh generation with a low number of elements and nodes. Considerable computational effort may be saved with the use of this finite pipe element.
05/00981 Viscosity correlations for minor constituent fluids in natural gas: n-octane, n-nonane and n-decane Huber, M. L. et al. Fluid Phase Equilibria, 2004, 224, (2), 263-270. Natural gas, although predominantly comprised of methane, often contains small amounts of heavier hydrocarbons that contribute to its thermodynamic and transport properties. In this manuscript, we review the current literature and present new correlations for the viscosity of the pure fluids n-octane, n-nonane, and n-decane that are valid over a wide range of fluid states, from the dilute gas to the dense liquid. The new correlations represent the viscosity to within the uncertainty of the best experimental data and will be useful for engineers working on viscosity models for natural gas and other hydrocarbon mixtures.
Transport, storage 05/00982 Effect of H2-injection on the thermodynamic and transportation properties of natural gas Sehouten, J. A. et al. International Journal of Hydrogen Energy, 2004, 29, (11), 1173-1180. Condensation of hydrocarbons due to temperature and pressure changes in the pipelines plays an important role in the transportation of natural gas. Injection of hydrogen might change this condensation behaviour considerably. The influence of hydrogen on the thermodynamics upon injection, on the Joule-Thomson effect at the pressure reduction stations, on the energy density, on the Wobbe index, and on the pressure drop in the pipelines has been calculated. It has been shown that injection of 25% hydrogen may lead to a temperature drop of several degrees, the temperature drop at the pressure reduction stations reduces by one-third, and the pressure drop in the transport
Fuel and Energy Abstracts
May 2005
151
Derived liquid fuels 05/00976 A comparative experimental study on the liquefaction of wood Zhong, C. and Wei, X. Energy, 2004, 29, (11), 1731-1741. Aqueous liquefaction of Cunninghamia lanceolata, Fraxinus mandshurlea, Pinus massoniana Lamb. and Populus tomentosa Carr. was carried out in an autoclave in the reaction temperature range of 553.15-633.15 K, where both non-catalytic and catalytic liquefaction were performed. The experimental results show that the lignin content has a large effect on the yield of liquefaction products in the non-catalytic liquefaction. The addition of K2CO3 as a catalyst can significantly reduce the residue yield for all the woods tested, while its effect on the heavy oil yield becomes weaker with decreasing amounts of lignin. The present study shows that a heavy oil yield of 30% coupled with a residue yield of less than 10% can be obtained for all the wood samples tested in the catalytic liquefaction.
05100977 Towards sustainable production and use of charcoal in Kenya: exploring the potential in life cycle management approach Kituyi, E. Journal of Cleaner Production, 2004, 12, (8-10), 1047-1057. The study seeks to demonstrate the potential role that industrial ecology could play towards energy poverty reduction and environmental conservation in Kenya through sustainable charcoal production and consumption. This is achieved through an exploration of the application of the life cycle management (LCM) concept that identifies various opportunities for technological intervention for energy and environmental conservation and reduction of material and energy losses. It also identifies opportunities for income generation at various stages of the product's life cycle; an aspect critical in poverty reduction in developing countries. The study finds that applying LCM in the charcoal trade in Kenya can deliver social, economic and environmental benefits to developing country communities and should, therefore, be promoted. However, appropriate legal, policy and institutional frameworks must exist in these countries for this to occur.
03
GASEOUS FUELS Sources, properties, recovery, treatment
05•00978 Effect of low pH on the activity of hydrogen utilizing methanogen in bio-hydrogen process Kim, In. S. et al. International Journal of Hydrogen Energy, 2004, 29, (11), 1133 1140. The pH is one of the most important parameters for producing hydrogen in biological processes. The major effect of low pH is the inhibition of the methanogenie activity in anaerobic biological processes for the production of hydrogen and, in general, it is considered that a pH below 5 can inhibit the methanogenic activity. In a semi-continuous reactor for the production of hydrogen, the pH was maintained at 4.5 d=0.2 by fixing the influent alkalinity to 1000 mg/l
as CaCO3. The primary fermentation product in this pH range was butyrate. The rate of hydrogen production stabilized at 35:55 ml/g Glu-day after 35 days. The yield efficiency of hydrogen was relatively low due to the methanogenic activity. The methanogenic activity originated from the hydrogen utilizing methanogen, and was inhibited by the addition of nitrate. At pH 4.3, the butyrate type of fermentation was changed to the butanol type and, simultaneously, the production of hydrogen stopped.
05100979 Oxidative dehydrogenation of ethane on Tecontaining MoVNbO catalysts L6pez Nieto, J. M. et al. Catalysis Today, 2004, 91 92, 241 245. Ethylene has selectively been obtained during the oxidative dehydrogenation of ethane on a Mo-V-Te-Nb-O mixed oxide catalyst. The catalyst was prepared hydrothermally and heat-treated at 600°C for 2 h in a nitrogen stream. For comparison, undoped and Te-doped Mo-VNb-O catalysts and Mo-V-Te-O and Mo-Te-Nb-O mixed oxides have also been prepared. The catalytic performance of the Mo-V-Nb-Te-O mixed oxide catalyst cannot be explained by the incorporation of Te on the surface of a Mo-V-Nb-O mixed oxide but by the presence of an orthorhombic TezM20057 (M = Mo, V, Nb) crystalline phase. The role of tellurium in these catalysts is also discussed.
05100980 The thermal and mechanical behaviour of structural steel piping systems Fonseca, E. M. M. et al. International Journal of Pressure Vessels and Piping, 2005, 82, (2), 145-153. The temperature, the deformation and the stress field in thermomechanical problems play a very important role in engineering applications. This paper presents a finite element algorithm developed to perform the thermal and mechanical analysis of structural steel piping systems subjected to elevated temperatures. The new pipe element with 22 degrees of freedom has a displacement field that results from the superposition of a beam displacement, with the displacement field associated with the section distortion. Having determined the temperature field, the consequent thermal displacement produced in the piping systems due to the thermal variation can be calculated. The temperature rise produces thermal expansion and a consequent increase of pipe length in the structural elements. For small values of the ratio of the pipe thickness to mean radius, the thermal behaviour can be calculated with adequate precision using a onedimensional mesh approach, with thermal boundary conditions of an axisymmetric type across the pipe section. With this condition, several case studies of piping systems subjected to elevated temperatures and mechanical loads are presented and compared with corresponding results from commercial finite element codes. The main advantage of this formulation is associated with reduced time for mesh generation with a low number of elements and nodes. Considerable computational effort may be saved with the use of this finite pipe element.
05/00981 Viscosity correlations for minor constituent fluids in natural gas: n-octane, n-nonane and n-decane Huber, M. L. et al. Fluid Phase Equilibria, 2004, 224, (2), 263-270. Natural gas, although predominantly comprised of methane, often contains small amounts of heavier hydrocarbons that contribute to its thermodynamic and transport properties. In this manuscript, we review the current literature and present new correlations for the viscosity of the pure fluids n-octane, n-nonane, and n-decane that are valid over a wide range of fluid states, from the dilute gas to the dense liquid. The new correlations represent the viscosity to within the uncertainty of the best experimental data and will be useful for engineers working on viscosity models for natural gas and other hydrocarbon mixtures.
Transport, storage 05/00982 Effect of H2-injection on the thermodynamic and transportation properties of natural gas Sehouten, J. A. et al. International Journal of Hydrogen Energy, 2004, 29, (11), 1173-1180. Condensation of hydrocarbons due to temperature and pressure changes in the pipelines plays an important role in the transportation of natural gas. Injection of hydrogen might change this condensation behaviour considerably. The influence of hydrogen on the thermodynamics upon injection, on the Joule-Thomson effect at the pressure reduction stations, on the energy density, on the Wobbe index, and on the pressure drop in the pipelines has been calculated. It has been shown that injection of 25% hydrogen may lead to a temperature drop of several degrees, the temperature drop at the pressure reduction stations reduces by one-third, and the pressure drop in the transport
Fuel and Energy Abstracts
May 2005
151