Effect Of Minerals On Pyrolysis And Combustion Characteristics Of Shenmu Coal

Pyrolysis is the most important reaction in coal technology since it is the basic process for the manufacture of coke, tar and gases from coal and the initial and accompanying reaction of coal hydrogenation, combustion and gasification. Much milder reaction conditions are needed to meet the demand for energy saving and economical coal conversion processes. The catalysts are generally effective in coal pyrolysis and product distribution.Raw, demineralized and with additive of ores(coal/ore=10/1) Shenmu coal samples were used in this work. The effect of atmosphere, temperature and ores on pyrolysis of coal samples was studied in a fixed-bed, and tar compositions from pyrolysis of coal with different ores were analyzed by GC. Thermal gravimetric analysis (TGA) was used to investigate the effect of inherent-mineral and additive ores on coal pyrolysis and combustion characteristics. The effects of ores on gas evolution during pyrolysis were detected by TG-MS, and the kinetic parameters of coal combustion were determined.1) Pyrolysis atmosphere and temperature have great influence on coal pyrolysis. At the same pyrolysis temperature, active atmosphere could promote the pyrolysis reaction, and the relative sequence of char yield as follows:N2>Mix Gas(10%CO,25%CO2,25%CH4,40%H2)>H2. With the increasing temperature tar yield increases, but too high temperature resulted in the decrease of tar yield.2) The TGA study indicated that inherent minerals could promote coal pyrolysis, while inhibit coal combustion activity. The final pyrolysis conversion and the maximum rate of weight loss of demineralized coal are lower than those of raw coal, while the temperature with the maximum combustion rate of demineralized coal is about26℃lower than that of raw coal.3) Ores have great influence on coal pyrolysis and combustion behavior. Char and tar yields of coal with ores are lower than those of raw coal at the same temperature in H2. The low tar yield may belong to the catalysis effect of ores and lead to the tar into small molecular gas. Among three kinds of ores, No.1ore (main composition is FeO(OH)) could improve the volatile yield of coal pyrolysis, which increases by1.88wt.%(daf) compared to that without addition of ore. The GC analysis of tar indicated that the total content of olefin and alkane in tar from coal samples with ores decreases obviously, and the content of light aromatic compounds, such as benzene, toluene and xylene, increases. The No.1ore is the best additive in promoting coal combustion among three ores, which made the temperature of the maximum combustion rate decrease about25℃.4) The research on the effects of inherent-mineral and ores on coal combustion and the kinetic study indicated that the combustion kinetic can be described with a one-order reaction equation, and the demineralized coal has lower activation energy. Different ores have different effects on coal combustion. The No.1ore could promote coal combustion activity, and the effect of No.2ore is not obviously, and the No.3ore could inhibit coal combustion.