The Experimental Study And The Numerical Simulation Of Vaporization Of Refractory Oxides SiO₂During High-silicon Coal Combustion

The power plant which use coal will release a great deal of waste, includingsubmicron particle emissions which is harm to the enviroment, so it is interesting to studythe rule of emission of submicron particle. Siliceous minerals is the main mineral in thecoal, which can form submicron particle during thegasification-condensation, therefore, thispaper chose three high-silicon coals produced in yunnan xuanwei area, analyse the rule oftransformation of the siliceous minerals and the evaporation of silicon during thehigh-silicon coal combustion.At last this paper builds up a new model for the vaporizationof the refractory oxides-SiO₂in the coal and discusses the influence for the vaporization.This paper prepare the low temperature ash and high temperature ash, at the sametime used XRD and XRF analyse the compositions of mineral mattera in the coal. Thereport showed the main compositions of the mineral matters in the low temperature ash isquartz, kaolinite and a few of other mineral matter. The compositions of high temperatureash is quarze and anhydrite,however, the content of quarze increased and the kaolinitedisappeard. The next, the three kinds of low temperature ash was analysed byThermogravimetric Analysis to get the rule of transformation of the mineral matter in thecoal. The analysis showed that the kaolinite decomposed at590℃，calcite decomposed atthe850℃and anahydrite was gasification at1170℃。With the aim of better understanding the informationg of the gasification ofSiO₂duiring coal combustion, three kinds of coal was investigated by Fixed bedexperimental. It showed that SiO₂was more easily vaporization in the reducing atmosphere;when at the same concentration of O₂, SiO₂was more easely vaporization in the N2/O₂atmosphere than O₂/CO₂atmosphere; SiO₂was more easely vaporization with theconcentration of O₂rise in the O₂/CO₂atmosphere; at last, the coal is the highest rate ofSiO₂-vaporization, the second is low temperature ash and the last is pure SiO₂. At the end, this paper made the thermodynamic calculation of the refractoryoxides-SiO₂in the coal and the results show the vaporization of SiO₂be bound up withtemperature and atmosphere. At the same time, This paper builds up a new model for thevaporization of the refractory oxides-SiO₂in the coal and discusses the influence for thevaporization.