Influence of aromatic structure on pyrolysis reactivity of coal

01 Solid fuels (sources, winning, properties) the organic matrix of coal. However, sulphur is responsible of an important variation in the alteration style of the inorganic matrix of coal, modifying the scheme of leaching in some elements (mainly Fe, and in lesser extent, Si, K, P). These elements are preferentially removed from coal, immobilizing other species (Ca, Mg, Mn) by proportion as insoluble sulphates. 02101768 Elucidation of hydrogen behaviour in coal by using a tritium tracer method: Hydrogen transfer reaction of coal with tritiated gaseous hydrogen in a flow reactor Sutrisna, I. er cri. Energy & Fuels, 2001, 15, (5), 1129-l 138. The hydrogen transfer reactions of three Argonne coals with tritiated gaseous hydrogen were carried out using a flow fixed-bed reaction system in the presence of Pt/A1203 catalyst at a temperature range 200300°C and under pressure of 1.5-5.0 MPa to trace the behaviour of hydrogen in coal. In the reactions under a constant pressure of 5.0 MPa, the hydrogen exchange between tritiated hydrogen atoms generated from the Pt catalyst and hydrogen in functional groups such as hydroxy groups proceeded at temperatures as low as 200°C for all coals studied. The hydrogen transfers to decompress ether linkages and reduce carbonyl groups in coal proceeded substantially at temperatures as low as 200°C for lignite Beulah-zap (ND) and middle rank Illinois No. 6 (IL) coals. The amount of functional groups in the tritiated coal achieved a maximum at 250°C for all coals examined. Hydrogen exchanges with hydrogen in the benzylic position and the phenoxy ring were observed at a perceptible extent at 300°C. Substantial decarboxylation of lignite ND coal was also observed at 300°C. When the pressure dependence was investigated at a constant temperature of 25O”C, the amount of hydroxy groups in tritiated coal increased with both the decompression of ether linkages and the reduction of carbonyl groups. 02/01769 Estimation of lignite reserve in the Kalburcayiri field, Kangal basin, Sivas, Turkey Tercan, A. E. and Karayigit, A. I. Internrrtiond Jortrnol of Coal Geology, 2001, 47, (2), 91-100. This paper addresses a case study on global estimation of lignite reserve in the Kalburcayiri field from the Sivas-Kangal basin, which is one of the most productive lignite basins in eastern Anatolia, Turkey. The two lignite seams, which were developed in a fresh-water lacustrine depositional environment during the Pliocene time, are currently being exploited in the Kalburcayiri open-cast mine for feed coal to a power plant with 300-MW capacity. Tonnage, thickness and quality parameters (ash yield, total sulphur content, and calorific value) of the lignite are variables considered in this study. The global estimates of these variables together with 95% confidence limits are obtained using the approximation principle of global estimation. A random stratified grid is fitted to available boreholes; the variograms for thickness and lignite quality parameters are estimated and modelled. The models are used in calculating. estimation error variances that will later be used in constructing 95% confidence intervals for the true values. 02/01770 Geological barrier - a natural rock stratum for preventing confined karst water from flowing into mines in North China Zhou, W. and Li, G. Environ. Geol. (Berlin, Ger.], 2001, 40, (8), lOO31009. Coalfields in North China encompassing more than ten provinces contain six to seven coal seams in the Permian-Carboniferous strata. The lower three seams, accounting for 37% of the total reserves, are threatened with karst water from the underlying Ordovician limestone. Many incidents of water seeping from the limestones have occurred in which a large amount of water suddenly flows into tunnels or working faces under high potentiometric pressure and over 30 mines have been flooded over the last 20 years. Large-scale dewatering or depressurizing of the karst aquifer was considered essential to avoid water inflow and keep the mine operation safe. This practice has caused sinkholes, dry springs, water supply shortage, and groundwater contamination in the surrounding areas, which is environmentally not permitted. One of the alternative water control measures is to make full use of the rock layer between the coal seam and the karst aquifer as a geological barrier. Similar to the application in the nuclear industry where a geological barrier is used to contain radioactive wastes the barrier of this application is considered a hydraulic barrier as well with the objective to prevent or constrain water flow from the underlying aquifer into mines. Its effectiveness to constrain water flow is described by a parameter referred to as hydrofracturing pressure (Phr). When the water pressure in the underlying aquifer exceeds Phf, a wedging effect takes place within the fractures of the geological barrier and, as a result, water upflow occurs. In-situ hydrofracturing tests were used to detect Phf in bauxite and silty sandstone at tunnels. The PI,‘ in the silty sandstone is larger than that in the bauxite but they both vary with depth (distance from the bottom of the tunnel). Based on the test results, a new safety criterion for water influx was derived for mines and it has been successfully applied to mining practices with the

minimum effort of dewatering in the karst aquifer. The same criterion can also be applied to tunnelling and quarrying in areas with similar geological conditions. 02/01771 Influence of aromatic structure on pyrolysis reactivity of coal Takagi, H. er al. Proc. - Annu. Inr. Pittsburgh Coal Conf., 2000, (17),

44-52.

Yallourn coal, which had been oxidized at 60°C with aq. H202 in the presence of I-propanol, was solubilized in ethanol at a yield of 80 wt%. Illinois #6 coal was depolymerized by treatment with trifluoromethanesulfonic acid in methylcyclopentane at 120°C. The yield of THF extracted was increased to 89 wt%. The solubilized coals were further hydrogenated by using Ru catalysts at 120°C for 12-72 h under a hydrogen pressure of 10 MPa. Phenolic resin and polystyrene samples were used as the model polymer and were also hydrogenated over the Ru catalyst under the same conditions. The aromatic structures in coals and model polymers were hydrogenated without cracking the structure. The pyrolysis reactivity of the treated coal and model polymers was evaluated by using a Curie-point pyrolyser at 500-764°C in a stream of helium. The reactivity of the treated coals and model polymers was greatly enhanced as a result of the hydrogenation. A good correlation between the aromaticity (fa) and the yield of volatiles was detected for both the treated coals and phenolic resins, but not for the polystyrenes. This suggests that pyrolysis reactivity was related to the aromatic structures of the main chains, and that those structures were changed by the hydrogenation. 02lO1772 Kinetics of water adsorptionldesorption on bituminous coals McCutcheon, A. L. et al. Energy & Fuels, 2001, 15, (6), 1387-1395. The kinetics of water adsorption and desorption on nine bituminous coals of various ranks have been studied, mainly at 26°C. To quantify the sorption kinetics, isobaric water uptake vs time data have been fitted by an empirical stretched-exponential model. This model provides good fits to water uptake data throughout the entire equilibration process at relative water vapour pressures (relative to saturation pressure) in the range of O-O.9 for all coals investigated. This represents a distinct advantage over simplified Fickian models which are valid for only a portion of the data within the short and long time limits. A flow rate kinetic parameter has been introduced to quantify the rate of water transfer from outside the coal particle to the intraparticle pore structure. Most of the bituminous coals investigated in this study have similar flow rates at relative pressures in the range of 0.2-0.9. However, for two coals of rank approaching that of semianthracites, the flow rate is significantly less than for all other bituminous coals investigated. This difference is caused by differences in the coal structure. Variations between coals in the flow rate at low relative pressures (o-0.2) appear to be caused by variations in the primary adsorption site which is largely detained by the coal oxygen content. The oxygen containing functional groups also influences the flow rate at low relative pressures during water desorption. 02/01773 Method for evaluation of coal quality to predict coke drum strength Saito, K. and Kato, K. Jpn. Kokai Tokkyo Koho JP 2001 324,460 (Cl. GOlN24/08), 22 Nov 2001, Appl. 2000/139,759, 12 May 2000. 7. (In Japanese) The method is carried out by high-temperature measuring coal (single coal, blended coal, treated coal) with H’-NMR imaging, to detect transverse relaxation time at the temperature of softening and melting coal and the coefficient calculated by the its existence degree inside the coal particle, to establish the relationship among the detected values and coke drum strength, for predicting the coke strength after carbonization. 02/01774 Methods for determination of fluorine in coal samples Nemec, J. and Havranek, V. Sbornik Vedeckych Praci Vysoke Skoly Banske-technicke Uniaerzity Ostrava, Rada Hornicko-Geologicka, 46, (3), 83-89. (In Czech)

2000,

Comparison of two methods of detecting fluorine in brown coal samples is presented. A non-destructive PIGE (proton-induced gamma-ray emission) method and a method using a combination of oxygen combustion and ISE (ion-selective electrode) were used. Fluorine values in tested samples vary from 60 to 1330 ppm. A discrepancy of slightly higher extent then expected between the two methods was disclosed. The PIGE method revealed much higher values than the method normalized for detection of fluorine. The reasons for such a divergence as well as the principles upon which the methods are based are also discussed. 02lO1775 Mineralogy and trace element contents Akalin seam, Gelik mine, Zonguldak-Turkey Karayigit, A. I. Energy Sources, 2001, 23, (8), 699-709. Fuel and Energy Abstracts

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