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The effects of extraction temperature and density on the characteristics of the extracts from supercritical fluid extraction (SCFE) of a high-ash Brazilian coal, with toluene as primary solvent, were experimentally investigated. The influence of addition of 5 mol% ethanol on the characteristics of the extracts was also studied. The experimental conditions ranged from 593 to 673 K and 4.7 to 11.5...
Acid-catalysed reaction of selected coal model compounds in trifluoromethanesulfonic acid (TFMS) in the presence of isopentane at 30-150°C was studied, to clarify the catalytic function of TFMS in coal depolymerization reactions. Diphenylmethane (DPM) and benzyl phenyl ether (BPE) were almost completely converted, producing alkylated monocyclic compounds at 30°C. Compounds with a phenolic hydroxyl...
The mechanism of coke strength development in coking of a conventional coal blend was investigated to find the preferred heating pattern for the production of coke of homogeneous quality. Relations of some coke properties to maximum coke temperature (MCT) (850-1040°C) or heating rate (2.5-13.2 K min -1 in the head zone next to the oven wall, 3.3-7.5 K min -1 in the tail...
A series of palladium-promoted Mo catalysts was prepared by two-step impregnation procedure using an ultrastable HY zeolite carrier. The mutual effect of Pd and Mo phases and zeolitic support was investigated in hydrodesulfurization (HDS) of dibenzothiophene (DBT) and diesel oil (1.1 wt% S). Pd/HY was more active than its binary PdMo/HY counterparts, suggesting an inhibitory effect of Mo on Pd....
Some relations between the ash yield (db) and the mineral and chemical composition of coals and their high-temperature ashes were studied. Low-ash coals (< 10 wt%) are enriched in moisture, volatile matter, fixed carbon and minerals such as montmorillonite, Fe, Al and Mg oxyhydroxides, dolomite, witherite and Fe sulfates, while their ashes are abundant in MgO, CaO, Na 2 O and TiO 2...
The sulfur removal potential of the water-soluble fraction of fly ash in oxydesulfurization of coal was investigated using some high-sulfur Turkish lignites. The effects of the amount of fly ash used, temperature, partial pressure of oxygen and time were studied in the ranges 5-40 g, 403-498 K, 0.0-1.5 MPa and 15-90 min respectively. The extents of pyritic and organic sulfur removal and recoveries...
Electron paramagnetic resonance in the X-band (9.3 GHz) was used for investigations of petrographically complex coal samples (densities 1.24-1.28 and 1.30-1.36 g cm -3 ) from Polish medium-rank coal (85.6 wt% C) heated in an inert atmosphere at 300-650°C. A strong increase in total concentration of paramagnetic centres in the sample of lower density at 300-350 and 450-550°C was measured...
The aim of this work is to present a new strategy for daily quality control in kerosene production. Exploratory data analysis of kerosene batches monitored during 5 years allowed extraction of nine essential variables from a total set of 26. A new 5 year period was used for confirmatory purposes, revealing good agreement between conclusions from both data sets. Once essential variables were...
A semi-empirical gasification kinetic model is developed and the most common rate models are reviewed. Comparisons are made with experimental data for lignite char and published data on chars of coal, peat and biomass. In the gasification experiments, finely ground lignite char samples of 0.5-1 g were gasified in a thermobalance at atmospheric and elevated pressures, at temperatures between 750...
A new classification of crude oils was developed using gas chromatography. With the LSER equation of Abraham et al., five parameters (intermolecular interaction terms) were obtained characterizing physicochemically 47 crude oils. This classification is in good agreement with the crude oil chemical composition and constitutes a first step in the explanation of their behaviour in the production steps.
A coal liquefaction extract was hydrocracked in the presence of several metal carbonyls, organometallic catalyst precursors and a mixture of fullerites. Hydrocracking conversions and product quality achieved when using these materials (a set of metal carbonyls, Mo and Ni octoates and Mo naphthenate) were compared with the performance of a commercial presulfided NiMo/Al 2 O 3 supported...
The determination of the average molecular parameters of bitumens represents an important step in describing the skeletons of asphalt cements. A new investigation method is presented, based only on the analysis of 13 C nuclear magnetic resonance (n.m.r.) data and molecular weights. This method is proved to be an efficient procedure to give independent parameters and to try to define...
Two coal tar pitches and a petroleum pitch were fractionated by extrography on a preparative scale. The chemical composition of the fractions was determined by elemental analysis, FT-i.r., 1 H n.m.r. and solidstate 13 C n.m.r. spectroscopies and number-average molecular weight, M n , and their thermal behaviour was studied using thermal analysis techniques (t.g., d.t...
This paper presents a comprehensive numerical modelling of the strongly swirling gas-particle turbulent flow and pulverized coal combustion in a novel vortex combustor (VC) recently developed for commercial heating applications. A comprehensive two-dimensional coal combustion model is developed which incorporates a new algebraic Reynolds stress turbulence model (ASM). The numerical results for an...
The effect of the presence of limestone and dolomite in coal, and calcium in lignite, on atmospheric-pressure temperature-programmed reduction (AP-TPR) analysis was studied. AP-TPR experiments were carried out on a bituminous coal with added limestone and dolomite and on a demineralized lignite. The results showed that both calcium minerals captured the gaseous H 2 S formed under AP-TPR...
Residual tar from a coal gasification plant was characterized using a wide array of analytical techniques. Structural comparisons were made with a coke oven tar and a crude oil flash-column residue. The gasification tar residue was found to have a carbon aromaticity >94%, with extensively dealkylated aromatic structures and only small amounts of oxygenates, compared with the 56% carbon aromaticity...
Oxidative pyrolysis of mixed solid wastes by both sand bed and freeboard reaction in a fluidized bed reactor was investigated. Air was the fluidizing gas (i.e. primary air, injected into the dense solids region) and secondary gas (i.e. injected into the freeboard). The effects were examined of (1) pyrolysis temperature (in both main and secondary combustion chambers) and (2) dimensionless air factor...
The effects of heating programmes, varied charge density and the insertion of partitions parallel to the wall of the oven chamber were investigated as means of obtaining coke of homogeneous quality in the direction of the oven width. The following results were obtained. (1) The difference in the strength after gasification with CO 2 at 1100°C (CSR) was reduced by increasing the heating rate...
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