No abstract

The pyrolysis tests of Shenhua coal and Shenhua direct liquefaction residue have been carried out using thermogravimetric at the differential heating rate. The kinetic parameters k and E were calculated using DAEM method. Results show DAME model can describe the pyrolysis behavior of Shenhua coal within the range of 20% to 95%, the activation energy of coal pyrolysis ranges from 53.98 to 279.38 kJ/mol, and DAME model can describe the behavior of Shenhua direct liquefaction residue within the range of 10% to 80%, the activation energy of residue pyrolysis is about 170 kJ/mol. The results of which are basically consistent with the experimental data.

The sulfur transformation during pyrolysis and gasification of three kinds of coals was studied and the release of H2S and COS during the process was examined. During pyrolysis, besides the property of coal, reaction temperature is the most important factor that affects the sulfur removal. The main sulfur-containing gases is H2S, the ratio of sulfur-containing gases amount to total sulfur amount in coal reaches 25.8% for LS coal, 31.8% for YT coal and 13.1% for HJ coal, respectively. During CO2 gasification, compared with pyrolysis and steam gasification, there are more COS and less H2S formation, because CO could react with sulfide to form COS. During steam gasification, only H2S formation and no COS detected, because H2 has stronger reducibility to form H2S than CO. And the formation rate of sulfur during gasification is consistent with the gasification reactivity of three coal chars, indicated that coal rank is the major factor which affects the sulfur distribution during gasification.

The CO2 gasification of three coal chars were investigated for determining the gasification reactivity and the kinetic parameters. Experiments were conducted in a fluidized-bed reactor at temperature of 1173 k, 1273 k and 1373 k at atmospheric pressure. Gasification kinetic parameters of the samples were determined using Homogeneous model and shrinking-core model. It is found that the gasification reaction under chemical-reaction-rate control, the gasification reactivity of coal char are strongly dependent on the rank of coals and gasification temperature. Both models could describe CO2 gasification equally well, these kinetic values are comparable with the reported in the literature for the other chars under chemical control conditions.