Numerical Analysis of Coal Combustion in Circulating Fluidized Bed
combustion of coal is used in circulating fluidized bed combustion system. This work is concerned about gas–solid two-phase mixtures flowing upwards through the fast beds. The type of information resulting from various ways of analyzing the pressure variations and the effect of superficial velocity on pressure in fluidized beds are discussed. This paper presents the standard k–є and two-phase turbulence model used to describe the gas–solids flow in a CFB.The analysis of temperature and density in coal combustion is done by discrete phase model (DPM) and non pre mixed combustion in species model through the PDF file creation in DPM model. The flow temperature and density in the system were modeled by solving the continuity and momentum equations of the gas flow by using the CFD analysis. The fluidizing velocity has been taken as 4 m/s and the effects of operating parameters on mole fraction, mean density and mean temperature are discussed in this paper. It is observed that the mean density of minimum and maximum mean mixture fraction along the scaled variance is significant.
Numerical Study Effect of Secondary Air Mass Flow to Characteristics of Circulating Fluidized Bed Boiler
In this paper, computational study of Circulating Fluidized Bed (CFB) combustion is analyzed. The results are concern about volume fraction and velocity distribution along the boiler. Simulation result were present in velocity, volume fraction, and pressure profile in boiler. All discussed result are applicable to all type of fluidized bed boiler. This paper will concern about how fluidization and combustion occur in boiler. Simulation present in unsteady state, multiphase direction, k-ε standard turbulence model, species transport combustion model and DPM. In this simulation, fuel, air, and other input materials are defined by actual data from power plant operation. As a result of analysis, the variation of secondary air does affect the characteristics of fluidization and combustion in CFB system. The superficial velocity is found around 4.1 m/s. The pressure generated is about 6642.3 Pa in the windbox area, and in the middle furnace area about -868.6 Pa. KeywordsCirculating Fluidized Bed Boiler, Secondary Air Mass Flow, Fluidization, Multiphase.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).