Metodologia para o estudo da porosidade de dolomita em ensaio de sulfatação interrompida/ Methodology for the study of the dolomite porosity in essay of interrupted sulfation

Ávila, Ivonete; Crnkovic, Paula M.; Milioli, Fernando E.
2010-01-01

Resumo em inglês The aim of this work is to propose a methodology to evaluate the evolution of the pore blockage of limestone during the sulfation reaction. The experiments were performed for a national limestone (dolomite) with average particle size of 545 μm in interrupted sulfation tests were conducted at seven different times and at three different temperatures of the process. The empirical data were obtained from porosimetry tests to establish BET surface area, volume and averag (mais) e size of pore and distribution of pore sizes of the sulfated samples. Thermogravimetric tests were performed to evaluate the preparation methodology of the samples used in the porosimetry tests.

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Interpretação do mecanismo de difusão no processo gás-sólido da reação de dessulfurização/ Interpretation of the mechanism diffusion in the gas-solid process of the dessulfurization reaction

Mortari, Daniela Andresa; Crnkovic, Paula Manoel; Ávila, Ivonete; Milioli, Fernando Eduardo
2010-01-01

Resumo em inglês The present paper aims to interpret the SO2 diffusion mechanism process for two different limestones: a calcite and a dolomite. In previous study, the apparent activation energies for sulfation reaction were between 3.03 and 4.45 kJ mol-1 for the calcite, and 11.24 kJ mol-1 for the dolomite. Using nitrogen porosimetry it was possible to observe that the dolomite presents mesopores of 0.03 μm, while the calcite presents mesopores of 0.01 μm. The evaluation of lim (mais) estones porous structure together with their kinetic parameters, allowed concluding that the diffusion mechanism follows Fick law and Knudsen law for dolomite and calcite, respectively.

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O efeito da granulometria na decrepitação durante a decomposição térmica de calcários e carvão/ The particle size effect on decrepitation during the thermal decomposition of limestones and coal

Crnkovic, Paula Manoel; Polito, Wagner Luiz; Silva Filho, Claudionor Gomes da; Milioli, Fernando Eduardo; Pagliuso, Josmar Davilson
2004-02-01

Resumo em inglês The use of fluidized bed combustors to burn coal is largely studied to permit the addition of limestone to capture SO2. The particle size for coal and limestone is an important parameter in this process. Thermogravimetry (TG) is used to elucidate the combustion and sulfation processes, but the experimental parameters must be evaluated to be representative in fluidized bed combustors. In the present study the effect of particle size is analyzed in the calcination of limest (mais) ones and the combustion of coal through the thermogravimetric curve for limestone and derivative thermogravimetric curve for coal. Small peaks representing mass losses between 400 and 500 ºC are observed due to the jumping of particles out of the crucible. This effect, recognized as decrepitation is observed for mid-sized particles provoked by the release of water vapor trapped within their lattice.

Scientific Electronic Library Online (Portuguese)