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Thermodynamic Analysis of Trace Elements Partitioning in AFBC Combustion of Lignite
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SYSNO ASEP 0166457 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Thermodynamic Analysis of Trace Elements Partitioning in AFBC Combustion of Lignite Author(s) Smolík, Jiří (UCHP-M) RID, ORCID, SAI
Ondráčková, Lucie (UCHP-M) RID, ORCID, SAI
Schwarz, Jaroslav (UCHP-M) RID, ORCID, SAI
Leitner, J. (CZ)
Sýkorová, Ivana (USMH-B) RID, ORCIDSource Title Abstracts, Volume., 1 / Wang Ch.-S.. - Taipei, 2002 - ISBN 986-80544-1-9 Pages s. 191-192 Number of pages 2 s. Action International Aerosol Conference /6./ Event date 09.09.2002-13.09.2002 VEvent location Taipei, Country TW - Taiwan, Province of China Event type WRD Language eng - English Country TW - Taiwan, Province of China Keywords combustion aerosols ; fluidised bed combustion ; trace element partitioning Subject RIV CF - Physical ; Theoretical Chemistry R&D Projects GA104/00/1297 GA ČR - Czech Science Foundation (CSF) Annotation In combustion of fosil fuels aerosol particles are formed from volatilised matter and non-volatilised mineral components of ash. As a result many of the potentially toxic trace elements are enriched in the submicrometer aerosol fraction. In this study we used global equilibrium analysis for prediction of trace element behaviour during fluidised bed combustion. The theoretical predictions were compared to the results of experimental scale measurements of trace elements partitioning between bottom ash and coarse and fine fly ashes from the Atmospheric Circulating Fluidised Bed Combustion of lignite. METHODS We combusted lignite from open pit mine Bílina, Czech Republic (proximate analysis: Wa 18.6, Ad 11.5, St 0.9, So 0.61, Q 29.7 MJ/kg; ultimate analysis (): C 70.65, H 5.37, N 0.91, S 0.61, 0 22.46). Main components of ash are silica (49.6) and alumina (36.22). The ash contains further oxides of Fe (4.17), Ti (2.98), Ca (2.49), Mg (1.11), Na (1.23), K (0.81), and Mn (0.02). The elemental compositi on was determined by PIXE and INAA and the following concentrations of trace elements (ppm) were found: As 2.3, Cl 33.1, Co 9.4, Cr, 49.1, Cu 25.3, Hg 0.07, Ni 37.9, Sb 0.25, V 117.8, and Zn 41.4. The experiments were done using 100 kW ACFB boier with sand as a material of bed. The boiler is equipped by a primary recirculating hot cyclone followed by an economizer and secondary cyclone that separates particles larger than about 5 micro m from the flue gas. The smaller particles were separated downstream of the secondary cyclone by a low-pressure BLPI impactor. Combustion was carried out with fuel feed 11 kg/h and air feed 100 m3/h. During the experiment we measured spatial temperature profile in the whole unit and determined flue gas composition.The mean temperatures in the bed, free-board, primary cyclone, secondary cyclone and the temperature of sampling were 900, 750, 650, 300, and 140 degrees C, respectively. After the preliminary calibrations at the temperature of sampling, the impactor should size-segregated f ly ash into 10 size fractions with aerodynamic diameter ranging from 0.016 to 14.3 micro m. But, SEM revealed that overloading of upper stages of impactor occurred (though stages 6-9 were doubled to prevent it) resulting in particle bounce and penetration into the lower stages. Following the SEM micrographs the sample from impactor was therefore divided into two fractions with particle sizes approximately < 1 micro m and > 1 micro m. Trace element concentration in the bottom ash, fly ash separated by the secondary cyclone and two size fractions collected in impactor were determined by PIXE and INAA. Workplace Institute of Chemical Process Fundamentals Contact Eva Jirsová, jirsova@icpf.cas.cz, Tel.: 220 390 227 Year of Publishing 2003
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