共查询到20条相似文献，搜索用时 31 毫秒
1.
V. Kress 《Contributions to Mineralogy and Petrology》2000,139(3):316-325
We present a new formulation to describe the thermodynamics of liquids in the system O-S-Fe. The model is based on an associated
regular solution formulation. According to this model, liquids in the O-S-Fe ternary are made up of an equilibrium solution
of the six melt species S, Fe, FeO, FeO1.5, FeS and FeOS. The model presented here represents oxygen and sulfur fugacities as well as phase equilibria with stoichiometric
solid phases better than models from the literature on O-Fe and S-Fe binaries. Furthermore, this model represents a substantial
improvement on the model of Kress (1997), which is the only other thermodynamic model available in the ternary system. Asymmetric
regular solution parameters are required along the FeO join in order to reproduce experimental data with the chosen list of
species. Symmetric regular solution parameters are required along the Fe-S binary. Mixing between any of the species considered
and FeOS close to ideal. The associated solution model presented here will serve as a more solid foundation for future models
in O-S-Fe- Ni-Cu liquids. Efficient and robust strategies for calculating equilibrium speciation and estimating model parameters
are presented.
Received: 15 June 1999 / Accepted: 5 February 2000 相似文献
2.
This paper presents a simple analytical solution to Fredlund and Hasan's one‐dimensional (1‐D) consolidation theory for unsaturated soils. The coefficients of permeability and volume change for unsaturated soils are assumed to remain constant throughout the consolidation process. The mathematical expression of the present solution is much simpler compared with the previous available solutions in the literature. Two new variables are introduced to transform the two coupled governing equations of pore‐water and pore‐air pressures into an equivalent set of partial differential equations, which are easily solved with standard mathematical formulas. It is shown that the present analytical solution can be degenerated into that of Terzaghi consolidation for fully saturated condition. The analytical solutions to 1‐D consolidation of an unsaturated soil subjected to instantaneous loading, ramp loading, and exponential loading, for different drainage conditions and initial pore pressure conditions, are summarized in tables for ease of use by practical engineers. In the case studies, the analytical results show good agreement with the available analytical solution in the literature. The consolidation behaviors of unsaturated soils are investigated. The average degree of consolidation at different loading patterns and drainage conditions is presented. The pore‐water pressure isochrones for two different drainage conditions and three initial pore pressure distributions are presented and discussed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
The goal of this paper is to present an analytical solution to have a first insight of the impact of ice formation on the surrounding porous rock on underground cavities like reservoir, pipes, tunnels or wellbores. Among the other analytical solutions found in the literature on this topic, the originality of this work resides in the rigorous theoretical framework of poromechanics, which considers the coupling between liquid water and ice crystal under thermodynamic equilibrium. Liquid water transport, thermal conduction, and elastic properties of the phases are also considered. Two analytical solutions are presented, based on a linearization of the system of governing equations. The first one deals with a spherical cavity within an infinite porous medium leading to an exact analytical solution. It allows validating the Stehfest’s algorithm on the numerical inversion of Laplace Transform, used in the second analytical solution, which considers a cylindrical excavation. The validity of this solution is assessed by comparing its results to that issued from a numerical resolution of the nonlinear system of equations. The analytical solution is then ultimately used to identify the influence of key parameters like the thermal/hydraulic conductivities, the amount of ice formed and the thermal dilatation coefficients on the mechanical response of a cylindrical cavity submitted to an internal frost. 相似文献
4.
Mark S. Ghiorso Ian S. E. Carmichael Mark L. Rivers Richard O. Sack 《Contributions to Mineralogy and Petrology》1983,84(2-3):107-145
The compositions of liquids coexisting with experimentally grown crystals of olivine, plagioclase, clinopyroxene, orthopyroxene, leucite, spinel, rhombohedral oxide, melilite and potassium feldspar are used to define, through mass action expressions of liquid/solid equilibrium, compositional derivatives of the Gibbs free energy of mixing of naturally occuring silicate liquids as a function of temperature, pressure and the fugacity of oxygen. The available experimental data describe these derivatives over a range of compositions which includes basic magmas. Therefore, for silicate liquids in this composition range, the topology of the Gibbs free energy of mixing can be approximated from experimental determinations of its derivatives. The majority of the existing thermodynamic data on the liquid phase is consistent with the application of regular solution theory to model the free energy of mixing. Strictly symmetric, temperature and pressure independent, regular solution interaction parameters are calibrated from this phase equilibrium data using regression techniques which have their basis in inverse theory. These techniques generate numerically stable interaction parameters which incorporate inter-variable correlation and account for experimental uncertainty. The regular solution model fits the available data on anhydrous silicate liquids to within the accuracy of the thermodynamic database +/?550 cals). Extensions to regular solution theory allow water solubility in more silica rich liquids to be modelled somewhat less accurately (+/?750 cals). The topology of the excess free energy of mixing surface is strongly asymmetric, possessing a single multicomponent saddle point which defines a spinodal locus. Given this prediction of a multicomponent spinode, a mathematical procedure based upon minimisation of the Gibbs free energy of mixing is developed for the calculation of the compositions of coexisting immiscible liquids. Predicted binodal compositions substantially agree with elemental liquid/liquid partitioning trends observed in lavas. Calculations suggest that an immiscible dome, in temperature-composition space, intersects the liquidus field of the magma type tholeiite. Immiscible phenomena are predicted at sub-liquidus temperatures for the bulk compositions of more basic or alkalic lavas, but are absent in more siliceous rock types for temperatures of the metastable liquid down to 900 K. The regular solution model is used in four petrological applications. The first concerns a prediction of the binary olivine-liquid phase diagram. The calculated geometry exhibits a minimum near Fa75, which, though not in accord with experimental results on the pseudobinary system, compares quite favorably with olivine-liquid phase equilibria interpreted from rhyolites, namely that the olivine phenocrysts of rhyolites are more iron rich than their coexisting liquids. The second petrological example concerns estimating the depth of the source regions of several basic lavas whose compositions cover a range from ugandite to basaltic andesite. The third application is a calculation of the saturation temperatures and compositions of plagioclase and olivine in four experimental basaltic liquids and a prediction of the liquidus temperatures and first phenocryst compositions of the Thingmuli lava series of Eastern Iceland. Lastly, enthalpies of fusion are computed for a variety of stoichiometric compounds of geologic interest. These demonstrate good agreement with calorimetrically measured quantities 相似文献
5.
This paper presents a theoretical approach to analyse coupled, linear thermoporoelastic fields in a saturated porous medium under radial and spherical symmetry. The governing equations account for compressibility and thermal expansion of constituents, heat sink due to thermal dilatation of water and thermal expansion of the medium, and thermodynamically coupled heat–water flow. It has been reported in the literature that thermodynamically coupled heat–water flows known as thermo-osmosis and thermal filtration have the potential to significantly alter the flow fields in clay-rich barriers in the near field of a underground waste containment scheme. This study presents a mathematical model and examines the effects of thermo-osmosis and thermal-filtration on coupled consolidation fields in a porous medium with a cavity. Analytical solutions of the governing equations are presented in the Laplace transform space. A numerical inversion scheme is used to obtain the time-domain solutions for a cylindrical cavity in a homogeneous or a non-homogeneous medium. A closed form time-domain solution is presented for a spherical cavity in a homogeneous medium. Selected numerical solutions for homogeneous and non-homogeneous media show a significant increase in pore pressure and displacements due to the presence of thermodynamically coupled flows and a negligible influence on temperature. © 1998 John Wiley & Sons, Ltd. 相似文献
6.
A. U. Zaman 《International Journal of Environmental Science and Technology》2013,10(3):455-464
Application and development of municipal solid waste treatment technology depends on various socio-economic and environmental factors. All those factors are work as development drivers for waste management systems. The study aims to identify key drivers from case studies of waste management development trend in Sweden. Social, economic and environmental drivers are identified and presented in this study. The study identifies personal behaviour, local waste management practice, consumption and generation of waste as the key social drivers. Resource value of waste, economic benefit from waste treatment facilities and landfill tax have been acknowledged as economic drivers for developing waste treatment technology. Moreover, global climate change, environmental movement and awareness have been working as environmental drivers for developing various waste treatment methods in Sweden. In addition, the study aims to analyse emerging waste treatment technologies based on a number of literature review and questionnaire survey. Dry composting, pyrolysis-gasification, plasma arc, and anaerobic digestion have been identified as potential emerging technologies for waste management systems in Sweden. 相似文献
7.
地下水微量有机污染 总被引：9，自引：1，他引：9
在简要评述其污染特征与研究特点的基础上，总结介绍了地下水微量有机污染的分布，污染物种类、性质、危害和来源，有机物的物化特征及其在环境中的迁移转化，以及污染控制技术。非极性难溶挥发性有机物（ＶＯＣ＇ｓ）是地下水中危害最大而又最为常见的有机污染物，主要由氯代脂肪烃（ＣＨＣ）和单环芳香烃（ＢＴＥＸ）构成。多数水溶相ＶＯＣ＇ｓ不易被吸附，在地下环境具有很强的迁移性，但在适当条件下可生物降解。非水溶相ＣＨＣ常在地下水中积聚潜伏于含水层底板，迁移不受地下水流向的控制；非水溶相ＢＴＥＸ则漂浮于地下水表面。非水溶相ＶＯＣ＇ｓ很难产生生物降解。ＶＯＣ＇ｓ的去除过程复杂，许多领域有待探索。 相似文献
8.
J. M. Anderson 《Geotechnical and Geological Engineering》1988,6(1):41-61
Summary This paper examines the methods presently available to apply refrigeration to a longwall district of a coal mine with particular reference to both the sources of heat and humidity around a district, and the specific locations which require cooling. Other methods to improve climatic conditions are also investigated and computer-predicted results from a district temperature prediction program are used for discussion.An approach to the solution of a climatic problem is explained with reference to other coal mine contaminants and an environmental design philosophy for deep high production districts in British coal mines is described. 相似文献
9.
The decomposition of solid waste materials in sanitary landfills produces liquids and gases which are deleterious to human beings, animals, plants and inorganic geologic materials. This paper presents a summary of leachate characteristics and discusses the effects of leachate on groundwater quality and carbonate strata. A system for site evaluation for purposes of sanitary landfill is also presented. The characteristics of the soil and rock at a site are included in the evaluation system through assessment of their infiltration potential, permeability, filtering capability and absorption potential. The characteristics of the groundwater at a site are taken into consideration through assessment of the substrate potential, buffering capacity and distributive potential (for contaminants). Formulae are stated to allow determination of evaluation parameters, and an example of the application of the rating system is presented. Use of the site-evaluation system will improve the quality of site selection and will reduce contamination and pollution problems created by construction of refuse landfills at unsuitable locations. 相似文献
10.
Robert G. Berman 《Geochimica et cosmochimica acta》1984,48(4):661-678
A thermodynamic model is proposed for calculation of liquidus relations in multicomponent systems of geologic interest. In this formulation of mineral-melt equilibria, reactions are written in terms of the liquid oxide components, and balanced on the stoichiometry of liquidus phases. In order to account for non-ideality in the liquid, a ‘Margules solution’ is derived in a generalized form which can be extended to systems of any number of components and for polynomials of any degree. Equations are presented for calculation of both the excess Gibbs free energy of a solution and the component activity coefficients.Application to the system CaO-Al2O3-SiO2 at one atmosphere pressure is achieved using linear programming. Thermodynamic properties of liquidus minerals and the melt are determined which are consistent with adopted error brackets for available calorimetric and phase equilibrium data. Constraints are derived from liquidus relations, the CaO-SiO2 binary liquid immiscibility gap, solid-solid reactions, and measured standard state entropies, enthalpies, and volumes of minerals in this system.Binary and ternary liquidus diagrams are recalculated by computer programs which trace cotectic boundaries and isothermal sections while checking each point on a curve for metastability. The maximum differences between calculated and experimentally determined invariant points involving stoichiometric minerals are 17°C and 1.5 oxide weight per cent. Because no solid solution models have been incorporated, deviations are larger for invariant points which involve non-stoichiometric minerals.Calculated heats of fusion, silica activities in the melt, and heats of mixing of liquids compare favorably with experimental data, and suggest that this model can be used to supplement the limited amount of available data on melt properties. 相似文献
11.
Compressed air energy storage (CAES) is a potential energy storage technology. The gas phase and short cycle period are two key factors affecting heat transfer loss in the wellbore of CAES. A semi-analytical solution was developed by using the convolution method considering gas movement in this study to describe the transient behavior of heat transfer with a short cycle period. The comparative analysis of the presented solution with two published solutions showed that the solution matched well with the previous solutions under steady state. Parametric studies were carried out to investigate the impact of injection rate, overall heat transfer coefficient and thermal diffusivity of the formation on heat loss in the wellbore. The results indicated that a low overall heat transfer coefficient and thermal diffusivity of the formation with an appropriate injection rate can efficiently reduce the heat loss. A hypothetical case study with a short cycle period of injection and production was conducted to demonstrate the applicability of the developed solution in CAES. The results suggest that the semi-analytical solution is applicable for heat transfer in the wellbore of CAES. 相似文献
12.
13.
An overview of fast pyrolysis of biomass 总被引：15，自引：0，他引：15
Biomass fast pyrolysis is of rapidly growing interest in Europe as it is perceived to offer significant logistical and hence economic advantages over other thermal conversion processes. This is because the liquid product can be stored until required or readily transported to where it can be most effectively utilised. The objective of this paper is to review the design considerations faced by the developers of fast pyrolysis, upgrading and utilisation processes in order to successfully implement the technologies. Aspects of design of a fast pyrolysis system include feed drying; particle size; pretreatment; reactor configuration; heat supply; heat transfer; heating rates; reaction temperature; vapour residence time; secondary cracking; char separation; ash separation; liquids collection. Each of these aspects is reviewed and discussed. A case study shows the application of the technology to waste wood and how this approach gives very good control of contaminants. Finally the problem of spillage is addressed through respirometric tests on bio-oils concluding with a summary of the potential contribution that fast pyrolysis can make to global warming. 相似文献
14.
R. V. P. Ferreira E. A. Silva R. L. S. Canevesi E. G. A. Ferreira M. H. T. Taddei M. C. Palmieri F. R. O. Silva J. T. Marumo 《International Journal of Environmental Science and Technology》2018,15(8):1629-1640
The treatment of radioactive liquid waste containing organic compounds was always a cause for concern to radioactive waste management facilities because the processes available are expensive and difficult to manage. Biosorption has been studied as a new process in simulated wastes as an alternative to treating them. Among the potential biomass, the coconut fiber has very attractive features that allow the removal of radionuclides using a low-cost biosorbent. The aim of this study was to evaluate the capacity of coconut fiber to remove uranium, americium, and cesium from real radioactive liquid organic waste. Experiments with the biosorption of these radionuclides in coconut fiber were made including (1) preparation, activation, and characterization of biomass and (2) biosorption assays. The biomass was tested in raw and activated form. Biosorption assays were performed, adding the biomass to real waste solutions. The solutions contain natural uranium, americium-241, and cesium-137. The contact times and the concentrations range were varied. The radioisotopes remaining concentration in the solutions was determined by inductively coupled plasma optical emission spectrometry and gamma spectrometry. The results were evaluated by maximum experimental sorption capacity and isotherm and kinetics ternary models. The highest sorption capacity was observed with the activated coconut fiber, with values of 2 mg/g of U (total), 70E?06 mg/g of Am-241 and 40E?09 mg/g of Cs-137. These results suggest that biosorption with activated coconut fiber can be applied in the treatment of radioactive liquid organic wastes containing uranium, americium-241, and cesium-137. 相似文献
15.
Rebecca A. Lange 《Contributions to Mineralogy and Petrology》1997,130(1):1-11
A revised model for the volume and thermal expansivity of K2O-Na2O-CaO-MgO-Al2O3-SiO2 liquids, which can be applied at crustal magmatic temperatures, has been derived from new low temperature (701–1092 K) density
measurements on sixteen supercooled liquids, for which high temperature (1421–1896 K) liquid density data are available. These
data were combined with similar measurements previously performed by the present author on eight sodium aluminosilicate samples,
for which high temperature density measurements are also available. Compositions (in mol%) range from 37 to 75% SiO2, 0 to 27% Al2O3, 0 to 38% MgO, 0 to 43% CaO, 0 to 33% Na2O and 0 to 29% K2O. The strategy employed for the low temperature density measurements is based on the assumption that the volume of a glass
is equal to that of the liquid at the limiting fictive temperature, T
f
′. The volume of the glass and liquid at T
f
′ was obtained from the glass density at 298 K and the glass thermal expansion coefficient from 298 K to T
f
′. The low temperature volume data were combined with the existing high temperature measurements to derive a constant thermal
expansivity of each liquid over a wide temperature interval (767–1127 degrees) with a fitted 1 error of 0.5 to 5.7%. Calibration
of a linear model equation leads to fitted values of Vˉ
i
±1 (cc/mol) at 1373 K for SiO2 (26.86 ± 0.03), Al2O3 (37.42±0.09), MgO (10.71±0.08), CaO (15.41±0.06), Na2O (26.57±0.06), K2O (42.45 ± 0.09), and fitted values of dVˉ
i
/dT (10−3 cc/mol-K) for MgO (3.27±0.17), CaO (3.74±0.12), Na2O (7.68±0.10) and K2O (12.08±0.20). The results indicate that neither SiO2 nor Al2O3 contribute to the thermal expansivity of the liquids, and that dV/dT
liq is independent of temperature between 701 and 1896 K over a wide range of composition. Between 59 and 78% of the thermal
expansivity of the experimental liquids is derived from configurational (vs vibrational) contributions. Measured volumes and
thermal expansivities can be recovered with this model with a standard deviation of 0.25% and 5.7%, respectively.
Received: 2 August 1996 / Accepted: 12 June 1997 相似文献
16.
This study describes the development of a green and sustainable strategy for the remediation of a contaminated site located in Chicago (IL, USA) to comply with the applicable federal and state environmental regulations. According to the site investigation results, many of the contaminant concentrations have been found to exceed the applicable regulatory limits that are protective of public health and local ecology. Polynuclear aromatic hydrocarbons, pesticides and heavy metals were found in the vadose zone soils throughout the site. Groundwater was found contaminated with lead or selenium in some locations. First, potential technologies to remediate the contaminated soils and groundwater at the site are identified. The most promising technologies are then systematically evaluated for sustainability based on qualitative and quantitative analyses. Sustainability considerations include greenhouse gases and other air pollutant emissions, water use, and personal injury, among others. Phytoremediation is selected to treat the majority of the site by utilizing existing and new plant species to reduce the concentrations of the contaminants. Solidification/stabilization is selected for “hot spot” treatment (high concentration area treatment) only at certain specific areas that have high concentrations of metals in the vadose zone. Monitored natural attenuation is selected for groundwater treatment. 相似文献
17.
Drop calorimetry measurements made between 900 and 1800 K are reported for six MO-SiO2 liquids (M = Li2, K2, SrandBa) and two titanium alkalisilicate melts. These results, together with data from the literature, are used to derive a model for calculating the heat capacity of Al-free silicate melts as a function of temperature and chemical composition. Twenty-one major or minor oxides have been considered and, except for K2O-bearing melts, the available data do not indicate deviations of the heat capacities from an additive function of composition. Simple energy calculations show that large variations of the temperature of the liquids result in structural changes of a magnitude similar to those of crystal-liquid transitions. It is suggested that network-modifier cations play an important role in changing the configuration of the liquid in response to temperature variations. The specificity of the behavior of the cations is shown by the lack of a simple relationship between the heat capacities of the liquids and characteristics of the alkali and alkaline-earth cations such as ionic potential or field strength. 相似文献
18.
An analytical solution for one-dimensional contaminant diffusion through multi-layered media is derived regarding the change
of the concentration of contaminants at the top boundary with time. The model accounts for the arbitrary initial conditions
and the conditions of zero concentration and zero mass flux on the bottom boundary. The average degree of diffusion of the
layered system is introduced on the basis of the solution. The results obtained by the presented analytical solutions agree
well with those obtained by the numerical methods presented in the literature papers. The application of the analytical solution
to the problem of landfill liner design is illustrated by considering a composite liner consisting of geomembrane and compacted
clay liner. The results show that the 100-year mass flux of benzene at the bottom of the composite liner is 45 times higher
than that of acetone for the same composite liner. The half-life of the contaminant has a great influence on the solute flux
of benzene diffused into the underlying aquifer. Results also indicates that an additional 2.9–5.0 m of the conventional (untreated)
compacted clay liner under the geomembrane is required to achieve the same level of protection as provided by 0.60 m of the
Hexadecyltrimethylammonium (HDTMA)-treated compacted clay liners in conjunction with the geomembrane. Applications of the
solution are also presented in the context of a contaminated two-layered media to demonstrate that different boundary and
initial conditions can greatly affect the decontamination rate of the problem. The method is relatively simple to apply and
can be used for performing equivalency analysis of landfill liners, preliminary design of groundwater remediation system,
evaluating experimental results, and verifying more complex numerical models. 相似文献
19.
20.
钼是典型的环境敏感元素，同时也是潜在的稀有金属元素，为了查明钼元素在原煤和煤灰中含量特征及其在固（体）液（体）间的迁移规律，选取陕南石煤及煤灰样为研究对象，利用电感耦合等离子体质谱仪（ICP-MS）分析样品中钼元素含量，通过浸泡实验模拟纯水、酸性、碱性和矿井水4种溶液中石煤及煤灰中钼元素浸出率。结果显示:石煤中钼元素含量为315.4~785.4 μg/g，煤灰中钼元素含量675.5~1 005.1 μg/g，燃烧后钼元素具有向石煤灰中富集（迁移）的趋势；不同类型溶液对石煤中钼元素均呈现不同程度的浸出率，总体特征为酸性溶液中钼元素的浸出率普遍偏低，低于其他3种类型溶液；而石煤灰中钼元素在不同溶液中浸出率不同于石煤样，总体特征为酸性溶液中钼元素的浸出率较高。结合浸出量进一步分析表明，酸性条件抑制了石煤中钼元素的迁出能力，而石煤灰样在酸性溶液中的钼浸出率与浸出量普遍高于其他类型溶液。分析认为，有氧燃烧使有机质释放钼元素、含钼矿热解、对钼的吸附能力等方面发生了变化，导致石煤灰中钼元素的迁移能力有所提升。研究认识具有环境保护和钼元素提取利用双重指导意义。 相似文献