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You search for char and 19,971 records were found.

Experimental work was carried out to study the kinetics of the carbon dioxide gasification of a coal char. The coal char was prepared from an Australian bituminous coal by pyrolyzing it at 900 °C in a tube furnace for 9 min in inert environment. The coal char was gasified in a thermo-gravimetric analyzer (TGA) with a mixture of carbon dioxide and nitrogen. The effects of gasification temperature (800-875 °C) and carbon dioxide concentration (10-80%) were studied. In the present study the reaction rate of the pyrolyzed coal was obtained and interpreted by Random pore model.
The reduction of FeO from iron-saturated FeO-CaO-Al2O3-SiO2 slags by graphite, coke and coal char at 1 673 K has been investigated using a sessile drop technique. Metallographic analysis of samples quenched from the reaction temperature, and in situ observations of the reaction interface, reveal significant differences in the slag/carbon contact, and in the morphologies of the product iron and its composition; these differences were found to depend on the carbon type used in the reduction. In particular it has been shown that, in the case of graphite and coke, liquid Fe-C droplets were rapidly formed at the slag/C interface. Reactions of the slag with coal chars, in contrast, result predominantly in the formation of solid iron. These observations indicate that the reaction pathways, and hence reaction kinetics, are dependent on c...
The effect of heat treatment on the structure of an Australian semi-anthracite char was studied in detail in the 850-1150degreesC temperature range using XRD, HRTEM, and electrical resistivity techniques. It was found that the carbon crystallite size in the char does not change significantly during heat treatment in the temperature range studied, for both the raw coal and its ash-free derivative obtained by acid treatment. However, the fraction of the organized carbon in the raw coal chars, determined by XRD, increased with increase of heat treatment time and temperature, while that for the ash-free coal chars remained almost unchanged. This suggests the occurrence of catalytic ordering during heat treatment, supported by the observation that the electrical resistivity of the raw coal chars decreased with heat treatment, while th...
A mimetic method based on Monte Carlo simulation is proposed to generate a molecular model of char. This char model consists of crystalline and amorphous phases, which are heated and cooled during the simulation of the carbonization process. Resultant char shows irregular shape and interconnected pores whose pr\operties depend on the percentage of non-organized carbon and the carbonization temperature. These chars were characterized with Monte Carlo integration techniques to obtain the pore size distribution, pore volume, solid density and surface area. These were then compared with the experimental data of two chars, longan seed derived char and coconut shell derived char. The results show that the molecular model captures the trend of the properties with carbonization temperature for both experimental chars. (C) 2008 Elsevier L...
The synthesis of a class of bis(imide-amine) curing agents for epoxy matrix resins is discussed. Glass transition temperatures and char yield data of an epoxy cured with various bis(imide-amines) are presented. The room temperature and 350 F mechanical properties, and char yields of unidirectional graphite fiber laminates prepared with conventional epoxy and imide-modified epoxy resins are presented.
Studies were performed to synthesize a novel class of bis (imide-amine) curing agents for epoxy matrix resins. Glass transition temperatures and char yield data of an epoxy cured with various bis (imide-amines) are presented. The room temperature and 350 F mechanical properties, and char yields of unidirectional graphite fiber laminates prepared with conventional epoxy and imide-modified epoxy resins are presented.
Char and pyrolysis zone depths give physical evidence of peak temperature reached in depth: The pyrolyzing material acts as a temperature indicator within its characteristic thermal decomposition range. A matrix of novel flexible ablators were laser tested in one component of material screening for NASA Entry, Descent and Landing research for future Mars missions. LHMEL tests were run both on virgin materials, and on previously charred materials for a dual pulse simulation of the heating due to aerocapture followed by atmospheric entry. The test models were machined to expose the cross-sections. Char measurements were made at three locations near the center of the exposed area. Data are presented showing the char depths developed in these flexible materials, grouped by reinforcing fiber and pyrolyzing material type.
A model for calculating the char conversion in biomass CFB gasifiers is presented. The approach is simplified and accounts for comminution phenomena, chemical reactions and fluid-dynamics. Theoretical submodels are developed, supported by semi-empirical relations to describe fluid-dynamics and reaction within fuel particles. There is also a discussion on the type of experiments needed to estimate the main input to the model by experiments conducted in lab-scale batch-operated FB. The model is useful for implementation as a submodel in existing CFB gasification models and also as a char conversion estimator in a pseudo-equilibrium model. Keywords: gasification; circulating fluidized bed; biomass conversion
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