Research On Thermochemical Kinetic Mechanism And Pollutant Emission Characteristics During Low Temperature Oxidation Of Blended Coals

With the development of port, coal mining, grain, chemical and power, the consumption of coal in China progressive increased year by year which leads China to become one of a few countries which take coal as the main source of energy. The problems existed in the usage of coal play a big role in power generation industry while it’s a kind of non-renewable mineral resources. For example, the low temperature oxidation of coal caused by the exothermic interaction between coal and oxygen in the air in the process of pileup lead to tremendous coal loss. The pollution emissions (CO, CO2,SOx, NOx,etc.) precipitated out from the low temperature oxidation process, has a significant effects on the environment. The reaction of low temperature oxidation takes places as long as the carbon material contact with oxygen in the air and lasts in the whole period until the coal pile heats up to approximately 300 ℃ which leads to the spontaneous combustion of coal.The study on thermochemical kinetic mechanism and pollutant emission characteristics during low temperature oxidation of blended coals was presented on the facts that the researches of low temperature oxidation in coal done by the former domestic and foreign scholars was confined to a single kind of coal’s thermochemical kinetic mechanism and pollutant emission characteristics.In this paper, three kinds of typical fire coal in southern-China area, coal from Australia, Indonesia and Shenhua, were selected to be analyzed by Switzerland-MettlerTM simultaneous thermal analyzer to get the thermodynamics characteristics. Through the analysis of thermos gravimetric curve (TG, DTG curves), research the individual, different types of coal mixing ratio and different coal ratio (1:9,3:7,7:3,9:1) thermodynamic properties of mixed; According to experimental results, the paper analyzes the the interaction rule of mixed coal low temperature oxidation process, blending ratio on the effects of low temperature oxidation process, choose a suitable model for the thermal dynamic analysis. And further application of thermos gravimetric-infrared spectrometry (TG-FTIR) technology of mixed coal low temperature oxidation process gas phase (precipitation characteristics were studied.Through the above experiment and calculation analysis, this paper mainly to the following conclusion:in the process of low temperature oxidation, collaborative interaction between different classes, with high volatile bituminous coal blending can to a certain extent, reduce the integrated oxidation properties of blend; High volatile bituminous coal blending of low temperature oxidation inhibition effect increased with the increase of the mixing proportion is not positively than trend, Indonesia coal and Shenhua coal mixing ratio to achieve best inhibitory effect of low temperature oxidation; Oxygen from the first stage of coal low temperature oxidation stripping stage of the reaction model for G(a)=[(1-α)-2-1]/2, the apparent activation energy between 62-83 kJ/mol, and the second stage of the reaction mechanism of oxygen increase heavy stage model for G(a)=[1-(1-α)1/3]2 the apparent activation energy (195-226 kJ/mol). Mixed gas phase precipitation characteristics of sample coal low temperature oxidation process of generation rate increases with the increase of mixed coal moisture content, Indonesia coal and Shenhua coal blending ratio 6:4,4:6 to suppress and emissions; The higher the volatile flux, the greater the activity of carbon more conducive to the reduction; Gas phase HCl with chlorinated organics, mainly from mixed coal pile has inhibitory effect on emissions of HCN and HCl.