Study On Modification Fly Ash And Absorption Of SO₂ In Flue Gas

Coal combustion not only led to seriously SO₂ gas pollution,but also produced a large number of solid waste fly ash,in order to reasonable utilization of fly ash,fly ash used to made into high performance absorbents absorption SO₂ in flue gas,so as to achieve the purpose of resource utilization and waste control by waste.The main components of fly ash were SiO₂ and Al2O3,it was mainly composed of spherical particles with smooth surface,irregular vitreous body and porous carbon particles.Based on the analysis of physical and chemical properties of fly ash,by modified experiments of fly ash to study the influence of four factors of fly ash hydration reaction,the primary and secondary factor order was reaction temperature,reaction time,fly ash-Ca ratio,the ratio of water-solid;the modification of fly ash of optimum conditions for the reaction temperature was 85℃,the reaction time was10 h,fly ash-Ca ratio was 5,the ratio of water-solid was 12,the specific surface area of 64.32 m2/g.Under the effect of activator,enhanced the modification effect of fly ash,the specific surface area and porosity were larger.Scanning electron microscopy（SEM）,X-ray diffraction（XRD）and Full automatic specific surface analyzer（BET）were used to analyze fly ash of before and after modified,the result showed that the effect of Na2SiO3·9H2O on the activity of fly ash was the best one,the fly ash structure was loose after modified,there were a large number of hydration products generation with the network structure.The specific surface area of modification fly ash was up to 106.70 m2/g as the weight of Na2SiO3·9H2O was 2 times as Ca（OH）2.The simulation FGD test showed that when the moisture content of 30%,the flue gas temperature of 110℃,the gas flow rate of300L/h,and the initial concentration of SO₂ was 2000 ppm,the absorption capacity was up to 148.536 mg/g.