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The mobility of > 30 trace elements from four Spanish coals was investigated using sequential extraction procedures. The total leachable fractions were obtained by comparing the total trace element content in the bulk coal samples with the extractable content. The high-temperature ash of these coals, and the fly ash and slag produced during the combustion of one of the coals in a large power...
The aim of this study was to determine the appropriate bridging liquid for lignites at selective agglomeration. Kerosene, diesel-oil, fuel-oil, spindle oil, heavy neutral, bright stock, light neutral and various surface active components were used. The best results were obtained with a mixture of 70% fuel-oil + 15% Acorga M5640 + 15% 2-ethyl hexanol or other alcohol type of reagents. It was determined...
The aim of this study was to determine the appropriate bridging liquid for lignites at selective agglomeration. Kerosene, diesel-oil, fuel-oil, spindle oil, heavy neutral, bright stock, light neutral and various surface active components were used. The best results were obtained with a mixture of 70% fuel-oil + 15% Acorga M5640 + 15% 2-ethyl hexanol or other alcohol type of reagents. It was determined...
Modelling coal pyrolysis using conventional kinetic methods demonstrates that at temperatures below 1073K the conversion of coal into coke can be treated as two competitive processes which take place in two apparent areas of the kinetic and diffusion range. The relative arrangement of these areas reflects the coking ability of individual coals. It has been shown that the effect of the ash content...
A VPO system was prepared from boiler-ash. VO(H 2 PO 4 ) 2 phase has been obtained at low temperature and characterized through a combination of techniques including TG-DTA analysis, X-ray powder diffraction and FT-Raman spectroscopy. The thermal decomposition of the precursor material gives a VO(PO 3 ) 2 and V(PO 3 ) 3 phase mixture. Supported...
Fly ash samples collected from two locations in the exhaust stream of a coal-fired power plant differ markedly with respect to the abundance of thin (~0.1μm) sulfur-rich surface coatings that are observable by scanning electron microscopy. The coatings, tentatively identified as an aluminum-potassium-sulfate phase, probably form upon reaction between condensed sulfuric acid aerosols and glass surfaces,...
This paper reports the control methods for mitigating fouling and slagging in brown coal-fired power utilities. Two control methods were investigated, i.e. wet pretreatment of coal and the use of mineral additives. By the first technique, samples of brown coal were treated with aluminium solutions to adjust the levels of Na, Al and Cl. The effect of cleaning was tested under closely controlled conditions...
Coal ashes from 17 mines were analysed in terms of ash yield and percentages of SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, K 2 O, Na 2 O, TiO 2 , P 2 O 5 , MnO, NiO. The composition has been analysed in terms of: (1) contribution to ash contents; (2) acidic, amphoteric and basic oxides; (3) co-ordination number in solid state;...
The purpose of this study was to identify possible events taking place during thermal treatment of biomass residue (bio-sludge) in an oxidative environment. The bio-sludge sample was collected after biological treatment of de-inking waste generated by pulp and paper mills. Combustion tests were conducted in a high-temperature Cahn TG-171 thermogravimetric furnace (TGA) coupled with Mattson Galaxy...
This study deals with curing of mortars in which coal ashes from both PC and FBC boilers were the sole binder components. The work focuses on the hydration products and the hydration results are correlated with the physical properties of the cured beams from 10 formulations of mortar made of sand and ash blends. Curing was extended to two to three years and the beam specimens were cured in water for...
In order to evaluate the environmental impact resulting from co-combustion of oily sludges, a detailed characterisation of the ashes produced was carried out.The main bulk composition and the trace elements were determined, thus allowing a comparison of the ashes produced from coal to those from co-combustion of the residue with and without limestone.The leachability was evaluated with two different...
This paper is part I in a series of two describing the modelling of the ash-chemistry of seven biomass fuels under reducing, pressurised conditions in fluidised bed gasification by means of thermodynamic multi-phase multi-component equilibrium (TPCE) calculations. The fuels considered were Salix, a Scandinavian forest residue, Miscanthus, Reed Canary Grass, Eucalyptus, Arundo Donax and Lucerne.The...
This paper is part II in a series of two. Ash behaviour modelling of the gasification of four biomass fuels is compared with pilot-scale experiments carried out in a pressurised fluidised bed gasifier at the Royal Institute of Technology (KTH) and an atmospheric test rig of Termiska Processer AB (TPS). Experiments were provocative with respect to agglomeration of the bed material. Thus, in the experiments,...
In fluidised bed combustion heterogeneous reactions catalysed by the bed material, CaO, and char are significant for the emission levels for instance of NO, N2O, and CO. The catalysts present in the bed affect significantly the selectivity of HCN and NH3 oxidation, which are known as precursors of NOx (i.e. NO and NO2) and N2O emissions from solid fuel combustion. Thus the catalytic activity of biomass...
Ferrospheres originating during the pulverised fuel firing of brown coals from the Chelyabinsk basin (South Urals, Russia) have been examined for determination of their chemical and phase compositions, morphology and formation conditions. Most of the ferrospheres are close to ideal spheres with dendritic or skeletal structure. The appearance of microsphere inner anatomy is determined by morphology...
The surface properties of coal and solution pH play a major role in determining the adhesion of microorganisms. In this study, three Indian coal samples with different compositions have been used and the adhesion of the bacterium Bacillus polymyxa to these coals has been investigated. It was found that due to the high ash content of coal, the zeta-potential was negative over most of the pH range which...
A by-product fly ash from oil shale processing was converted into zeolite by alkali hydrothermal activation using sodium hydroxide. The activation was performed at different activation temperatures using 8 M sodium hydroxide. The obtained cation exchange capacity (CEC) showed that the best condition for synthesis of zeolite performed in a closed reactor at 160 o C for 24 h. Powder patterns...
The main agricultural residues of Crete are considered to be of premium importance for local energy production through combustion. The thermal behaviour of ashes was predicted by chemical, mineralogical, microscopical and thermal analyses, while the removal of troublesome elements to reduce slagging and fouling in furnaces was tested by leaching these biomass fuels with water. Deposition tendencies...
In this study, the possibility of cleaning Sirnak asphaltite by the agglomeration method was investigated. Experimental studies were conducted on the asphaltite sample with ash, sulphur, volatile matter and fixed carbon contents of 44.8, 6.0, 38.0, and 17.2wt%, respectively. For this purpose, laboratory tests were carried out to investigate the effects of grinding time, bridging liquid type, bridging...
More than half of the recent large-scale FBC installations are designed to burn more than one fuel. Especially the use of various biofuels—as such or besides conventional fuels—is becoming more and more common in the new FBC projects. It is a major challenge to be able to understand and predict the behavior of the FBC system when co-firing of different fuels in different proportions. This paper reviews...
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