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Optimization of pulverised coal combustion by means of CFD/CTA modeling
(National Library of Serbia, 2006)
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Petrovski, Ilija
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Karas, Piotr
<jats:p>The objective of the work presented in this paper was to apply a method for handling two-phase reacting flow for prediction of pulverized coal combustion in large-scale boiler furnace and to assess the ability of the model to predict existing power plant data. The paper presents the principal steps and results of the numerical modeling of power boiler furnace with tangential disposition of the burners. The computational fluid dynamics/computational thermal analysis (CFD/CTA) approach is utilized for creation of a three-dimensional model of the boiler furnace, including the platen superheater in the upper part of the furnace. Standard k-e model is employed for description of the turbulent flow. Coal combustion is modeled by the mixture fraction/probability density function approach for the reaction chemistry, with equilibrium assumption applied for description of the system chemistry. Radiation heat transfer is computed by means of the simplified P-N model, based on the expansion of the radiation intensity into an orthogonal series of spherical harmonics. Some distinctive results regarding the examined boiler performance in capacity range between 65 and 95% are presented graphically. Comparing the simulation predictions and available site measurements concerning temperature, heat flux and combustion efficiency, a conclusion can be drawn that the model produces realistic insight into the furnace processes. Qualitative agreement indicates reasonability of the calculations and validates the employed sub-models. After the validation and verification of the model it was used to check the combustion efficiency as a function of coal dust sieve characteristics, as well as the impact of burners modification with introduction of over fire air ports to the appearance of incomplete combustion, including CO concentration, as well as to the NOx concentration. The described case and other experiences with CFD/CTA stress the advantages of numerical modeling and simulation over a purely field data study, such as the ability to quickly analyze a variety of design options without modifying the object and the availability of significantly more data to interpret the results. .</jats:p>
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VERIFICATION OF METHOD FOR ESTIMATING COMBUSTION EFFICIENCY IN A BUBBLING FB COMBUSTOR
(Vinča Institute of Nuclear Sciences, Belgrade, 2000-11)
Risto V. Filkoski
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Longin Przybylski
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Ilija J. Petrovski
The article refers to a mathematical method for estimating the efficiency of the combustion process in bubbling fluidised bed conditions. The calculation procedure used in this work is given elsewhere [1, 2] and, here, it is only briefly described. The objective of the present investigation is to validate the mentioned method when using brown coal as a fuel in a laboratory fluidised bed combustor. Particular attention is devoted to the subject of elutriation of fuel particles out of the combustor, considering the fact that it is one of the most important factors limiting the combustion efficiency and the furnace design as well. The work presented here contains the conditions and some results of experimental research in heat losses resulting from the phenomenon of elutriation of combustible particles [3]. Experiments were carried out in a combustor with an inner diameter of 200 mm and a height of 1200 mm. A numerical testing of the method for estimating the combustion efficiency was accomplished within a bed temperature range from 780 °C to 900 °C and a fluidising velocity from 1.20 to 1.32 m/s. The results achieved were compared with the experimentally obtained data. Besides the appearance of some deviations, it may be stated that the results are reasonable and in line with the expectations.
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Geometrical analysis and proof of the tangent line of evolvent tooth side on helicoidal gear
(Faculty of Mechanical Engineering, University "Ss. Cyril and Methodius", Skopje, Macedonia, 1990)
Napeska, Sofija
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Using of the dates and special files in the CAD systems
(Faculty of Mechanical Engineering, University "Ss. Cyril and Methodius", Skopje, Macedonia, 1993)
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Software for presentation of the 4D objects
(Faculty of Mechanical Engineering, University "Ss. Cyril and Methodius", Skopje, Macedonia, 1994)
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The model for calculating of concentration of pollutants in urban environments
(1996)
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Filkovski, Risto
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Computer program of Graphic presentation of the 4D objects
(1997)
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Joleski, Tome
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Stereometrical Projecting of three-dimensional and four-dimensional objects in curvilinear projective space
(1998)
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Dukovski, Vladimir
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Stereometrical Projectiong of three-dimensional and four-dimensional objects in hyperboloid projective space
(1998)
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Dukovski, Vladimir
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Stereometric identification of geometry and modelling of objects
(1999)
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Dukovski, Vladimir

Faculty of Mechanical Engineering

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