Single coal particle behavior in fluidized bed combustion

Single coal particle behavior in fluidized bed combustion

01 So/id fuels (sources, winning, properties) models can be incorporated into mine planning and scheduling. A case study demonstrates the efficiency o...

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01 So/id fuels (sources, winning, properties) models can be incorporated into mine planning and scheduling. A case study demonstrates the efficiency of the method in assessing risk associated with geological and engineering variables.

predicted from the equation well with the experimentally NMR.

02/01783 Single coal particle behavior in fluidired bed combustion Oka, S. N. ef al. Thermal Sciences 2000. Proceedings of the ASMEZSITS In/ernrr~ional Thermcrl Science Seminar, Bled, Slovenia. June I14, 2000, 2000, (I). 83-91. Edited by Bergles. Arthur E.; Golobic, Wok. This paper was written in order to follow coal particle behaviour and changes, and influence of bed temperature, fluidization velocity and coal characteristics, the following processes were experimentally investigated for coals of different rank: bed to coal particle heat and mass transfer, kinetics of de-volatilization process, particle fragmentation, ignition temperature and start-up temperature, combustion kinetics of parent coal and char, burning particle temperature history and bed to particle temperature difference, SOz self-retention by ash. Experimental research was supported by mathematical modelling of the particle heating and particle temperature distribution and history, particle fragmentation and char combustion-including char particle porosity change. In this paper most important results of this investigations are reviewed and illustrated by a number of experimental results and comparisons with mathematical models and experimental correlations.

02/01787 The coals of Urals Kornilkov, V. N. Izvesriya V.vsshikh Uchehnykh Zuvedenii, Gornyi Zhurnal, 2001, (2), 24-33. (In Russian) Analysis of the conditions and perspective development of coal deposits of Urals and its impact on the economy is presented.

02/01784 Structural analysis of coal through RICO reaction: detailed analysis of heavy fractions Murata, S. er al. Fuel, 2001, 80, (14) 2099-2109. Detailed analyses of RICO (ruthenium ion catalysed oxidation) products of bituminous and brown coals were conducted by using FDiMS and 13C-NMR. These analyses indicate that the aqueous phase fraction (water-soluble products) from RICO of brown coals consists of aliphatic dicarboxylic acids and aromatic polycarboxylic acids with longer alkyl side chains. The presence of benzene tetra-, penta-, or hexacarboxylic acid in the RICO products of brown coals might indicate that brown coals contain relatively large aromatic clusters with three or more rings. On the other hand, a similar fraction form RICO of bituminous coals seems to consist of mainly non-substituted aromatic polycarboxylic acids along with a small amount of aliphatie dicarboxylic acids. These differences could be explained based on the structural features of the sample coals. Bituminous coals contain relatively large condensed aromatic rings with fewer alkyl side chains or bridges, these easily being converted to aromatic polycarboxylic acids, while brown coals are comprised of smaller aromatic clusters with larger numbers of alkyl side chains or bridges, a portion of the aliphatic functional groups being converted to free acids with the remainder attached to the aromatic rings (i.e. production of ring-alkylated benzene polycarboxylic acids). Analysis of organic solubles from brown coals by ‘C-NMR and FD/MS indicates that this fraction contains a large amount of aliphatic carboxylic acids with longer alkyl groups up to carbon number 38, suggesting that brown coals contain longer alkyl side chains (up to 38) on aromatic rings. 02/01785 Structural studies of Permian ‘Gondwana’ coals of Barapukuria by infrared spectroscopy Podder, J. ef al. Indian J. P/y., 1999, 73A, (3), 2X3-293. IR spectroscopy is well suited for the characterization of highly absorbing materials particularly coal as it can provide information on both the organic and inorganic species of the coal matrix. The application of IR technique for the characterization of coal and mineral has been discussed in this paper. From the IR investigations Bangladeshi coals are revealed as higher rank of bituminous type with high calorific value and low ash and minerals are basically silicious nature. Coal samples are carbonized at different temperatures under argon atmosphere and examined by IR. Under carbonization increase in crystallite size or an increase in ordering of aromatic ring occurs, indicating the initial stage of graphitization. Stacking height and crystallite dimensions are also calculated by X-ray diffraction study. 02/01786 Structural studies of vitrinite concentrates of Indian coals by FTIR Bandopadhyay, A. K. ef al. Indian J. Phys.. A, 2000, 74A, (2) 195-198. Indian Association of the Cultivation of Science. Vitrinite rich fractions of Indian coals have been subjected to FTIR examination in order to derive information regarding their unusual features and quantity structural data on hydrogen distribution as aliphatic (H,i), aromatic (Har) and hydroxyl (Ho”). Aliphatic carbon, C,t, has been estimated assuming an aliphatic stoichiometry CHa and aromatic carbon C,,, has been obtained indirectly following Brown Ladner method. Aromaticity, f, (C&Z), has been computed from a knowledge of C,, and C, the total carbon. The correlation of aromaticity and H/C had led to the values regression equation; f, = 1.19 - 0.545*H/C. The aromaticity

for foreign coals have been found to agree detected values obtained from SPE 13C

The study on the petrographic properties and the 02lO1788 purification of Taixi coal, China Wang, Y. and Liu, J. Proc. L Annu. Im. Pir/shurgh Coal Conf., 2000, (17). 21662166. The’petrographic properties and washability of Taixi anthracite and the technological plan and measure for low-ash-coal manufacture from Taixi anthracite are discussed. The results of pilot tests and coal beneficiation after steps of modification are presented. 02/01789 Trace elements in the Lower Pliocene fossiliferous Kangal Iignites, Sivas, Turkey Karayigit, A. I. ef al. Interncrrional Journal of Coul Geology, 2001, 47, (2), 73-89. The Kangal lignite basin, which is one of the most productive lignite basins in eastern Anatolia-Turkey, includes two lignite seams containing abundant gastropoda shells in the Lower Pliocene Kalburcayiri Formation. The seams are currently exploited in an open-cast mine in the Kalburcayiri field and supply feed coal to a power plant with 300MW capacity. The average thickness of each of the two seams in this mine is about 10 m, and they are separated by about 20 m of tuffaceous sedimentary rocks. A 15-20.cm thick tuff bed occurs within the upper seam. The purpose of the study was to understand mineralogy and trace element conclusions of the two lignite seams in the Kalburcayiri Formation which were affected by volcanic ashes. Fifty-nine core samples of the lignites from seven boreholes across the basin, and eight channel samples from the working lignite seams were collected and analysed by proximate analysis, X-ray powder diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), and SEM (SEM) with energy-dispersive X-ray microanalyis techniques. The samples show that the worked lignite seams, on an as-received basis, contain high moisture contents (43.4-57.8%). All the samples on an air-dried basis have high ash yields (from 19.5% to 81.7%) and a broad range of total sulphur contents (from 1.16% to 7.04%), and calorific values (684 to 4621 kcalikg), except for two samples with no temperature rise due to high ash yield. The mineral matter of the studied samples is made up of calcite, quartz, feldspar, pyrite, opal-CT, clay minerals, gypsum and traces of aragonite. The trace element analyses, on a whole-coal dry basis, indicate that most of the borehole samples showed enrichment in specific elements, including Zn (151394 pg/g), MO (13-368 pg./g), and U (5.5-131 pgig), when compared to the range of these elements for most coals in the world. The contents of Zn, MO, and U for the samples from the worked lignite seams are, respectively, 38-187, 54-161 and 28-55 kg/g. The SEM studies show that Zn is hosted mainly in micron-sized Zn-bearing mineral (sphalerite), but no MO- and U-bearing minerals have been detected during these studies, except for monazites containing Th and U traces, The MO and U conclusions are negatively correlated with the ash yields, and these elements are contained mamly within organic matter. ;I;;:0

Trace metals

in coal: where are they and where

Kolker, A. er al. Proc. - Annu. Inr. Pirrshurgh Coal Cotrf., 2000, (17) I6. A review concerning the occurrence of trace metals in coal as detected via selective leaching, electron microprobe, ion microprobe, and X-ray absorption fine structure (XAFS) spectroscopic techniques, used in combination. Topics discussed include: As, Hg, Cr, and water quality. 02101791 X-ray photoelectron spectroscopy determination of the forms of nitrogen in Tongchuan coal and its chars Liu, Y. er al. Xi’an Jiaofong Da.xue Xuehuo, 2001, 35, (7), 661-665. (In Chinese) Pyrolysis experiment is carried out with a coal from Tongchuan, China under 773 K and 1173 K for 7 min in an electric Muffle furnace. The N Is spectra from pulverized Tongchuan coal and obtained chars are evaluated by XPS (XPS). The nitrogen in the coal is pyridinic, pyrrolic, quaternary nitrogen and nitrogen oxides. Dominating species is pyridine accounting for 37%, which is rarely observed. There is no nitrate in it. By heating coal in thin air atmosphere, quaternary nitrogen will be converted into pyridones and pyrrolic nitrogen enriched in coal char. N-oxide in the coal is formed when it is exposed to air and emits as volatile during severe pyrolysis. Fuel and Energy Abstracts

July 2002

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