Browsing by Author "Ozbayoglu,G."
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Conference Object Citation Count: 1Comparison of gross calorific value estimation of Turkish coals using regression and neural networks techniques(2012) Özbayoğlu, Gülhan; Ozbayoglu,M.E.; Ozbayoglu,G.; Energy Systems EngineeringGross calorific value (GCV) of coals was estimated using artificial neural networks, linear and non-linear regression techniques. Proximate and ultimate analysis results were collected for 187 different coal samples. Different input data sets were compared, such as both proximate and ultimate analysis data, and only proximate analysis data and only ultimate analysis data. It was observed that the best results were obtained when both proximate analysis and ultimate analysis results were used for estimating the gross calorific value. When the performance of artificial neural networks and regression analysis techniques were compared, it was observed that both artificial neural networks and regression techniques were promisingly accurate in estimating gross calorific values. In general, most of the models estimated the gross calorific value within ±3% of the expected value.Conference Object Citation Count: 0Maghemite - a source of heavy medium for coal washeries(2010) Özbayoğlu, Gülhan; Ozbayoglu,G.; Anaç,S.; Bulut,M.; Energy Systems EngineeringUse of magnetite as heavy medium in coal preparation plants has been increasing steadily in recent years. It might be in short supply in some areas or excessively costly in certain times. In Turkey, the cost of heavy medium magnetite has almost tripled since 2003. As a result, alternative sources of heavy medium material have been evaluated. A maghemite ore from Elbistan-Kahramanmaras was found to be an interesting source. Tests showed that the maghemite ore can be enriched via magnetic separation at 1556 gauss to obtain a heavy medium material with 4.93 g/cm3 density and 97.22 per cent magnetic recovery. Further tests were conducted to determine the optimum fi eld strength for magnetic separation, friability and regeneration recovery.Article Citation Count: 8Partitioning of major and trace elements of a Turkish lignite with size and density(2011) Özbayoğlu, Gülhan; Energy Systems EngineeringThis research was devoted to determine the concentration and distribution of major and trace elements in a Turkish lignite and to investigate the partitioning behaviour of them in various size and density fractions to estimate the possibility of removal of trace elements by conventional coal cleaning. Three size fractions which were used in industrial coal cleaning processes were chosen. Each size fraction was separated into various density fractions by float and sink tests, which were evaluated for major and trace elements. These tests showed that by applying the same size and density fractions of industrial coal cleaning processes, more than 70% of Mo, Nb, Nd, W, Hg and Zr could be removed, which were approximately equal to the result achieved for ash removal.Article Citation Count: 0Removal of hazardous air pollutants based on commercial coal preparation plant data(oficyna Wydawnicza Politechniki Wroclawskiej, 2013) Özbayoğlu, Gülhan; Energy Systems EngineeringThis paper investigates the concentration, distribution, and rejection of hazardous air pollutants, specifically identified by the US Clean Air Act Amendments of 1990, based on commercial coal preparation plant data obtained on-site. The samples were collected from the products of the different cleaning circuits of the operating plant. The concentrations of twelve potentially hazardous trace elements, including As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Se, Th and U in those samples were determined. Compared with the average concentration of the trace elements in Turkish coals, the run-of-mine coal fed to the existing plant appears to contain higher concentrations of Cd, Hg, Mn, Th and V. However, the concentrations of As, Cd, Cr, Mn, Se, Th, U and V of the run-of-mine coal are above the world averages. Cd, Cr, Hg, Mn, Pb and Th concentrations of run-of-mine coal were easily removed at commercial coal preparation plant refuse in the range of 51.8% to 77.4 %, while only a small reduction was achieved for U and V as they were concentrated in clean coals. The present study reveals that conventional coal preparation technologies could significantly reduce hazardous air pollutants concentrations in coal.Article Citation Count: 10Removal of hazardous air pollutants based on commercial coal preparation plant data(2013) Özbayoğlu, Gülhan; Energy Systems EngineeringThis paper investigates the concentration, distribution, and rejection of hazardous air pollutants, specifically identified by the US Clean Air Act Amendments of 1990, based on commercial coal preparation plant data obtained on-site. The samples were collected from the products of the different cleaning circuits of the operating plant. The concentrations of twelve potentially hazardous trace elements, including As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Se, Th and U in those samples were determined. Compared with the average concentration of the trace elements in Turkish coals, the run-of-mine coal fed to the existing plant appears to contain higher concentrations of Cd, Hg, Mn, Th and V. However, the concentrations of As, Cd, Cr, Mn, Se, Th, U and V of the run-of-mine coal are above the world averages. Cd, Cr, Hg, Mn, Pb and Th concentrations of run-of-mine coal were easily removed at commercial coal preparation plant refuse in the range of 51.8% to 77.4 %, while only a small reduction was achieved for U and V as they were concentrated in clean coals. The present study reveals that conventional coal preparation technologies could significantly reduce hazardous air pollutants concentrations in coal.