INFLUENCE OF PARTICLE SIZE IN A PULVERIZED COAL COMBUSTION PROCESS OF A REAL 160 MW POWER PLANT'S BOILER

Conrado Ermel¹; Leandro Luis Felipetto¹; Gian Marcos Gatti¹; Cristiano Vitorino da Silva¹

¹ Department of Mechanical Engineering - Universidade Regional Integrada do Alto Uruguai e das Missões

doi:10.20906/CPS/COB-2015-0202

Resumo

This article presents the results of numerical simulations of a combustion chamber that uses benefited coal type CE3100 as fuel. To perform the simulations was used the geometry of a steam generator of a full-scale thermal power plant of 160 MW situated in Rio Grande do Sul state, Brazil. Three approaches were undertaken to compare the influence of the particle size in relation to the Ash, Char, chemical species mass fraction and the temperature fields in the combustion process. In the first case, it was considered the particle size range of 50-80 µm, around 55 µm; in the second case, the ranging was of 80-100 µm, around 65 µm; and in the last case, of 100-120 µm, around 75 µm. In all cases there was an Eulerian modeling of the conservation equations of mass, momentum, energy and chemical species, as well as the k- turbulence model in process. The heat transfer by radiation for the gas phase was modeled by Discrete Transfer Radiation Model - DTRM, and the absorption spectrum of the flue gases was modeled by WSGG - Weigthed-Sum-of-Gray-Gases, adopting the latest weighted mean factors obtained from the literature. Was connected to this a Lagrangian modeling for predict the transport, devolatization and oxidation of pulverized coal particles, where the solid phase being patterned with black body. For solving differential equations, the commercial software Ansys CFX V15.0 was used. The main results showing that the size of the coal particles has some influence in coal combustion process, acting directly on the temperature, CO and O2 mass fraction fields in to the boiler.

Palavras-chave: CFD; Pulverized coal; Combustion; Boiler; Size particle