High Temperature Gaseous Equilibria—Computation and Graphical Representation

Abstract

A new technique—the constrained chemical potentials method—is presented for calculating high temperature gaseous equilibria and isillustrated on the calculation of the Gibbs triangle composition diagrams of the H-S-O and H-O-C systems taking into account the formation of all possible gaseous species. The influence of composition, temperature and total pressure on these systems is analysed. As well as showing the influence of the common thermodynamic variables upon the equilibrium, the coupling of this technique with the Gibbs triangle composition diagram is useful in resolving practical problems of pyrometallurgical importance such as: which mixture(s) of the common gases prepared at room temperature will produce a required gaseous equilibrium; which gases tend to be good or poor chemical buffers during an experiment; and which gases may pose kinetic problems in attaining equilibrium. The basic algorithm for a three or four component system can be stored in a small desk calculator since the method is dependent on the number of components and independent of the total number of species in the gas phase. The constrained chemical potentials method is general and the algorithm for calculating multicomponent equilibria is also presented.

Résumé

Une nouvelle technique—la méthode des potentiels chimiques imposés—est proposée pour le calcul des équilibres gazeux complexes à hautes températures. La méthode est appliquée au calcul de l'équilibre pour les systémes H-S-O et H-O-C en tenant compte de la formation de tous les composés gazeux. Les résultats sont présentés sous forme d'isobares inscrits dans le triangle de composition de Gibbs. L'examen d'un diagramme permet de voir: l'influence de la composition ou d'un changement de composition sur les pressions partielles (ou activites) de certains composés de la phase gazeuse; quels mélanges gazeux préparés à l'ambiante permettront d'obtenir les conditions à l'équilibre recherchées; quels types de mélanges gazeux possèdent de bonnes ou de mauvaises qualités de tamponnage chimique. Le calcul de tels diagrammes à des températures et des pressions totales différentes montre l'influence de ces variables thermodynamiques sur l'équilibre du système considéré. Un algorithme de la méthode des potentiels chimiques imposés, applicable à un système à plusieurs composants est aussi présenté.     

旧有沥青结构道路基层损坏冲击压实试验分析

较普通压路机相比,冲击式压路机不仅施工速度快、工程费用低,而且施工质量容易得到保证。结合某省道旧有沥青结构道路改造采用的冲击压实技术,得到一系列试验结果,并在此基础之上介绍了冲击压路机冲击压实机理,探讨并建议了在不同道路病害成因的情况下,冲击压路机型号选择、冲压效果的检测标准确定、冲压效果的评定以及相关注意事项。     

泡沫沥青冷再生混合料力学性能与结构参数研究

本文对泡沫沥青冷再生混合料的力学机理与路面维修结构层应用进行了阐述。通过在不同材质界面的粘结力试验对比了泡沫沥青与热沥青在粘结性能上的差异;根据不同混合料级配下的无侧限抗压强度与劈裂强度试验,分析了强度性能指标与混合料级配之间的相关程度,验证了泡沫沥青冷再生混合料在控制指标上的合理性。最后,通过抗压回弹模量的回归方差分析,提出了抗压回弹模量的建议取值,为泡沫沥青冷再生路面结构设计提供参数。     

The steric hardening and structuring of paraffinic hydrocarbons in bitumen

The formation of ordered structures of macro- and microcrystalline waxes during cooling from the melt of bitumen was observed using temperature-modulated differential scanning calorimetry. This process develops in time. It is found that steric hardening of bitumen (gradual hardening at room temperature) is related to the processes of formation of ordered structures of bitumen waxes.     

SBS的结构对改性沥青性能的影响

通过对线型及星型结构SBS对改性沥青稳定性,高低温性能,老化性能等方面影响的研究表明;线型SBS与星型SBS对于改性沥青各方面性能具有不同的影响,线型SBS对于改性沥青的低温性能主要在5℃延伸度可以达到70cm以上,同时改性沥青的稳定性良好,但软化点提高的幅度较小,星型结构的SBS对于改性沥青的高温性能影响较大,软化点比基础沥青提高幅度较大,但影响改性沥青的稳定性。     

深层含沥青白云岩储层岩石物理特征与测井评价方法

近年在川西地区泥盆系观雾山组见到了较好的储层分布,多口井获得工业气流.然而,川西观雾山组岩心缝洞中沥青充填严重,储层沥青含量和储层参数定量计算难度大.为此,从沥青对观雾山组储层定量影响分析入手,通过高温循环沥青溶解实验建立沥青溶解前后的孔隙度—声波时差、孔隙度—电阻率模型,采用纵波时差—横波时差、声波时差—电阻率等模型...     

A Systematic Method to Predict Cloud Point Temperature and Solid Precipitation

Abstract

Thin (1.0 mm) films of bitumens were oxidized at 60 and 80^○C under oxygen partial pressures of 3.1, 62.4, and 300 psi. Changes in the carbonyl and sulphoxide regions of the infrared spectra were monitored by measuring absorbance at 1, 730, 1, 685, and 1, 030 cm^?1. Relative changes in the measured absorbances at differing oxygen pressures were compared by plotting the results against absorbance at 1, 700 cm^?1. The results indicate that, over the pressure range studied, the relative rate of formation of different oxidation products (and by implication, the mechanism of the reaction) is unaffected by oxygen concentration in the film.     

The rheological properties of a bitumen emulsion modified with two types of SBR latex

Bitumen emulsions have recently been taken as one of the most frequently used binders for asphalt surface treatments (AST). Making use of modified bitumen emulsion is necessary to improve AST. Styrene butadiene rubber (SBR) is one of the most commonly used modifiers. The present research study tested the residue of normal and modified bitumen emulsion with different percentages of SBR and X-SBR using ordinary and dynamic shear rheometer methods. The findings revealed that increasing latex SBR led to increasing softening point and needle penetration, so that temperature sensitivity of bitumen residue is reduced. The stiffness of modified bitumen emulsion residue improved significantly by increasing the percentage of SBR. Furthermore, comparing the effect of SBR and X-SBR on bitumen emulsion uncovered that in equal polymer percentage of 6%, X-SBR promoted performance graded for at least one performance grade. Finally, the study is innovative as it dealt with the comparison of high-temperature performance analysis of the impact of polymer percentage simultaneous with that of SBR structure on improving bitumen emulsion.     

EXPERIMENTAL AND THEORETICAL STUDY OF THE PORE STRUCTURE AND DIFFUSION PROPERTIES OF AN EVOLVING HETEROGENEOUS MATERIAL: APPLICATION TO RADIOACTIVE BITUMINIZED WASTE

Placed in a geological repository, radioactive bituminized waste (BW) could be altered in the long term by water, leading to the release of chemical and radioactive elements. The main difficulty, in terms of experimental characterization, comes from the fact that the BW material evolves in time due to the swelling associated to the water osmotic flux. To overcome this difficulty, a new approach is proposed in this work, based on the leaching of BW samples in aqueous solutions where the chemical activity of water is controlled. These specific leaching conditions allow one to control the swelling of the degraded BW matrix. The chemical activity of water being fixed, the pore structure of the leached BW samples was quantitatively studied by ESEM pictures further treated by image analysis. In parallel, diffusion cells using radioactive tracers were used in order to measure mass transfer characteristics in the leached BW. Coupling image analysis with diffusion experiments for each degradation state leads to a diffusion coefficient-porosity relation that is then compared to standard diffusion models in biphasic materials.     

Green synthesis and characterization of SnO2, CuO,Fe2O3/activated carbon nanocomposites and their application in electrochemical hydrogen storage

The goal of this study is to produce environmentally friendly nanomaterials that have a high hydrogen storage capacity. The researchers in this study used inexpensive natural bitumen to produce activated carbon (substratum) and a green solution synthesis combustion method to produce CuO, Fe₂O₃, and SnO₂ nanoparticles using a Mint extract as the source material. Metal oxides such as CuO, Fe₂O₃ and SnO₂ are used to increase hydrogen storage capacity and Columbic efficiency. AC and AC/SnO₂, AC/CuO, and AC/Fe₂O₃ nanocomposites have been confirmed via XRD (X-ray diffraction), TEM (transmission electron microscopy), EDX (energy-dispersive X-rays), FT-IR (fourier transform infrared), scanning electron microscope (SEM), and adsorption and desorption analysis of N₂ (BET). In terms of discharge capacity, AC/CuO, AC/Fe₂O₃, and AC/SnO₂ display respective capacities of 2250, 2500, and 3600 mAh/g after 20 cycles, respectively. Of all the sample materials, the AC/SnO₂ nanocomposite with the highest hydrogen storage capacity has the lowest Columbic efficiency. This implies that a sample with 54% Columbic efficiency, such as AC/CuO nanocomposite, is a more suitable specimen.