| SO2is one of the most harmful air pollution sources at present.In order to control the emission of SO2exceeding the standard,a variety of desulfurizers have been studied.The desulfurization effect of fly ash modified has been greatly improved.The sink beads is a special kind of microbeads that can be separated from fly ash.They are similar to fly ash in chemical composition and have stronger"pozzolanic activity"than conventional fly ash.In this study,hydrothermal modification was carried out on the sink beads separated from fly ash by physical and chemical method,so that the modified sink beads could achieve the new function of removing SO2from flue gas.The optimal conditions of hydrothermal modification of sink beads were determined by orthogonal test and single factor test:reaction temperature 85℃,reaction time 12 h,pearl calcium ratio 5,water solid ratio 12.The mineral composition and particle morphology of the sink beads before and after hydrothermal modification were compared by physicochemical characterization and simulation test.The results show that the modified sink beads have larger surface area and more pores than the original ones,which was conducive to improving the efficiency of adsorption SO2removal from flue gas.The modified sink beads is formed into porous crystal materials such as calcium silicate hydrate,calcium aluminate hydrate,calcium silicate and aluminate hydrate,which is beneficial to improve its desulfurization efficiency.The effects of relative humidity,flue gas temperature and initial SO2concentration on the adsorption efficiency of modified precipitation sink beads were studied on a self-built simulated dry flue gas desulfurization experimental platform.The optimal conditions of modified sink beads adsorption SO2removal were obtained:relative humidity of 30%,flue gas temperature of 150℃,and initial SO2concentration of 850 mg/m3.Under these conditions,the desulfurization efficiency of 5 g modified sink beads reached 99.65%in 100 min,and the time to reach 100%desulfurization rate lasted 80 min.Finally,by comparing the adsorption efficiency of the modified sink beads and the traditional Ca（OH）2desulfurizer,it is verified that the modified sink beads as desulfurizer have better adsorption and removal performance of SO2.The test results show that:The desulfurization efficiency of Ca（OH）2decreased with time,and the highest desulfurization rate is 93.5%,while the desulfurization efficiency of the modified sink beads is stable,and the highest desulfurization rate is as high as 100%and lasts for 80 min,indicating that the desulfurization effect of the modified sink beads was much better than that of Ca（OH）2.It is concluded that high efficiency desulfurization can be achieved by hydrothermal modification of sinking beads. |
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