A study of oxy-coal combustion with steam addition and biomass blending by thermogravimetric analysis

摘要

The thermal characteristics of pulverized coal have been studied under oxy-fuel combustion conditions using non-isothermal thermogravimetric analysis (TG). The atmospheres used were 21%O _2/79%N _2, 21%O _2/79%CO _2, 30%O _2/70%O _2, and 35%O _2/65%CO _2. Coal blends of coal with 10 and 20% of biomass were also studied under these atmospheres. The addition of 10 and 20% of steam was evaluated for the oxy-fuel combustion atmospheres with 21 and 30% of O _2 in order to study the effect of the wet recirculation of flue gas. The results obtained were similar for all the different rank coals and indicated that replacing N _2 by CO _2 in the combustion atmosphere with 21% of O _2 caused a slight decrease in the rate of mass loss and delayed the burning process of the coal, biomass and coal/biomass blend samples. When the O _2 concentration was increased to 30 and 35% in the oxy-fuel combustion atmosphere, the rate of mass loss increased, the burning process occurred at lower temperatures and it was shorter in duration. An increase in the rate of mass loss and a reduction in burning time and temperature were observed after the addition of steam to the oxy-fuel combustion atmosphere. No relevant differences between the 10 and 20% steam concentrations were observed.