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Factors affecting the rheological characteristics of coal-water mixture (CWM) were investigated, including the properties of the coal, the volume fraction of solids and the mean size and size distribution of the coal particles. The apparent viscosity was measured with a Brookfield viscometer, and the non-Newtonian properties based on the power-law model were investigated using a Haake rotational...
The rheological characteristics of coal-water mixture (CWM) were investigated, including the effects of surfactant type and concentration, presence of added electrolytes and slurry temperature. The slurryability of coal could be enhanced considerably by the addition of surfactants and some electrolytes and the slurries almost exhibited shear-thinning behaviour, i.e. were pseudoplastic with n <...
During the carbonization of coal-tar pitch the viscosity of the pitch decreased at 200-360°C, reached a minimum at 360-400°C, and then increased at 400-450°C. The decrease of the viscosity of the pitch after its melting may be attributed to the solubilization of benzene insolubles (BI) (β-resin and quinine insolubles) by the solvation of benzene solubles (BS) to BI, in addition to the increase of...
The influence of the addition of petroleum coke as a micronized fraction to coal-water mixtures (CWM) was observed by rheological characterization at different temperatures. The addition of petroleum coke in this form improves the rheological properties of CWM at room temperature.
Pyrolytic carbon black (CBp), a by-product of scrap tyre pyrolysis, was blended with a 150200 penetration grade bitumen at concentrations ranging from 5 to 30 wt%. The fundamental rheological properties of standard and modified bitumens as well as their classical characteristics were determined. The interactions between CBp and bitumen components using ESCA, i.r. and u.v. spectroscopy were investigated...
A new type of synfuel composed of light oil, fine coal powder and water (OCWF) has been demonstrated as a promising clean fuel for replacement of light liquid fuel. This kind of fuel can offer several advantages over existing alternative fuels to oil such as coal-water mixture and coal-oil mixture in many respects, for example safety in transportation, lower ignition point than coal-water mixture,...
The rheological behaviour of a concentrated coal-water-fuel oil slurry was investigated with a tube viscometer, to optimize its formulation. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele, according to the experimental results obtained. A factorial plan was used and empirical equations were obtained which correlate rheological characteristics with the...
A low-viscosity water-based triplex synfuel composed of heavy oil, pulverized coal and water (HOCWF) was prepared by using a suitable dispersant and emulsifier. The effects of component content, temperature and dispersant content on the rheological properties of HOCWF were investigated. Preliminary combustion tests showed that this kind of synfuel had a high heating value and low soot formation.
Biomass is an often abundant, renewable, low ash and low sulfur fuel. Due to these properties, biofuels are promising alternatives for traditional petroleum-based fuel applications; however, traditional biofuels for internal combustion engines are not cost competitive with gasoline, diesel or fuel oils. One method to reduce the cost of biofuels is to use slurry fuels which have a potential lower...
A kind of oil-based multiphase slurry composed of heavy oil-coal powder-water (synfuel) was prepared by using suitable dispersant and emulsifier. The effects of components content, experiment temperature and dispersant content on its rheological properties have been investigated. It was observed that the synfuel showed pseudoplastic behaviour with apparent yield stress, and the apparent yield stress...
The present study gives a new understanding about bitumen's colloidal behavior, related to its chemical composition, microscopic structure and rheological properties. Bitumens possess a strong temperature dependence of rheological properties, governed by the interaction of the individual constituents. Much importance is given to the colloidal index of the bitumen, based on the ratio of the four main...
Triplex synfuels composed of residual oil, pulverized coal and water (OCWF) have been prepared. The ratio of the components oil (O) to coal (C) to water (W) by weight was O:C:W=4:2:4 for water-based synfuel, and O:C:W=5:2:3 for oil-based synfuel. It has been found that the rheological behaviour of water-based synfuel followed the Herschel-Bulkley model, whereas that of oil-based synfuel followed the...
This paper deals with the characterisation of the linear viscoelastic and steady-state flow properties of commercial pigmentable synthetic binders and unmodified bitumens. From the experimental results obtained, we may conclude that both types of materials show a thermorheologically simple linear viscoelastic behaviour in the temperature range studied (5 o C-50 o C), although synthetic...
Thermoplastic behaviors of 10 coals of various rank were studied by dynamic viscoelastic measurements using a rheometer. Elastic (G′) and viscous (G″) moduli, and tanδ in which δ is a phase delay of a stress to a strain applied to a coal pellet were determined at 300–550°C. The temperatures corresponding to softening, maximum fluidity state, and resolidification of coals could be estimated from a...
Over the past few years, rheology has been extensively used in order to classify and evaluate bituminous binders according to their performance properties. This has led to a better knowledge of bitumen behaviour that occurs when subjected to different thermal and mechanical conditions, as seen during road construction and service in the field.In the present work, rheology has been applied to evaluate...
Investigation methods for characteristics of movement along the tubes, combustion dynamics and gasification of separate drops were developed for the coal-water mixtures (CWM). The following parameters were determined on the basis of laser heating: thermometric, pyrometric and concentration dynamics of single-drop combustion, complete combustion times, duration of temperature phases of combustion,...
Precipitated wax, shear and thermal history have pronounced effects on viscosity and rheological behavior of waxy crudes. On the basis of mechanism of waxy crude rheology, a shear-rate-dependent viscosity model has been developed by applying theory of suspension rheology. This model is characterized by its capability to predict viscosities of crude oils with various thermal and shear history and beneficiated...
Mixing polymers into bitumen has important consequences on the engineering properties of bituminous binders. Thus, structural and chemical changes may be observed during processing of polymer-modified bitumens. Chemical compatibility and processing conditions are crucial to obtain suitable properties. Most polymers occur to be insoluble, in some degree, in the bitumen matrix, and phase separation...
Synthetic mesophase pitches, produced from naphthalene (ARA24, ARA24r), were examined in terms of fluidity and thermal stability in comparison with other mesophase, isotropic pitches, or mesophase pitch/softening molecules blends. Their interest for carbon/carbon (C/C) composites processing by liquid impregnation or vacuum transfer inside three-dimensional carbon preform is discussed. Viscosity versus...
The use of polymers for the modification of bitumen in road paving applications has been growing rapidly over the last decade as government authorities and paving contractors seek to improve road life in the face of increased traffic. Currently, the most commonly used polymer for bitumen modification is the elastomer styrene butadiene styrene (SBS) followed by other polymers such as styrene butadiene...
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