| Cleaning of industrial flue gas is important for improving air quality.In this thesis,we researched flue absorbtion abilities of SO2、NOx、CO2 by using steel slag and natural wollastonite CaSiO3(CS)as absorbents.First,SO2 desulfurazation properties of steel slag and CS were researched.The effects of reaction temperature,gas flow rate and absorbents size on removal rate of SO2 were studied and the absorbents after desulfurization were analyzed.The results show that in temperature range 30-80℃,with the increase of reaction temperature,decrease of gas flow rate and absorbents size,the removal rate of SO2 increased.Steel slag and CS’s removal rate of SO2 both reached 98.0%when reaction temperature is 60 ℃、gas flow rate is 4.2 m/h.The effects of reaction temperature and time on the reaction rate of CaO in steel slag were also investigated.The results show that the reaction rate of CaO was improved with the increase of reaction time and temperature and the reaction rate of CaO after reacted at 90 ℃ for 4 h reached 64.0%.Analysis from XRD and TG-DSC indicate that in the desulfurazation process,C2S in steel slag reacted with SO2 and produced CaSO3·0.5H2O,whereas MgO·2FeO in steel slag remained unreacted.With extension of reaction time,the content and the crystallinity of CaSO3·0.5H2O in abosorbent increased.NO2 denitrification properties of steel slag and CS were rsearched.The effects of reaction temperature,gas flow rate and absorbents size on the removal rate of NO2 were studied,and the absorbents after denitrification were analyzed.The results show that in temperature range 30-80℃,with the increase of reaction temperature,decrease of gas flow rate and absorbents size,the removal rate of NO2 increased.Steel slag’s removal rate of NO2 reached 97.0%,CS reached 90.0%when reaction temperature is 80 ℃、gas flow rate is 4.2 m/h.The effects of reaction temperature and time on the reaction rate of CaO in steel slag were also investigated.The results show that the reaction rate of CaO was improved with the increase of reaction time and temperature,and the reaction rate of CaO that steel slagafter reacted at 90℃ for 4 h reached 43.0%.Analysis from XRD and TG-DSC indicate that in the denitrification process,C2S in steel slag reacted with NO2 and produced Ca(NO3)2·4H2O,whereas MgO-2FeO in steel slag remained unreacted.CO2 sequestration by using steel slag powders as absorbent was researched.Furthermore,steel slag powders were pressed into blocks with 2×2×2 cm cubic shape,after they were carbonized we tested their compressive strength and carbon sequestration.The results show that after reacted at 90℃ for 3 h,15.2 g CO2 can be sequestrated by 100 g steel slag,and compressive strength of the slag test block reacted under the same conditions reached 47 MPa.Analysis from XRD and TG-DSC indicate that Calcium mineral in steel slag reaced with CO2 and produced CaCO3;FESEM observation show that a lot of CaCO3 generation.The effect of SO2 on the removal rate of NO2 was investigated under the condition of different reaction temperature and gas flow rate,the results show that SO2 can promote the removal of NO2,when reaction temperature is 80 ℃、gas flow rate is 4.2 m/h the removal rate of SO2 and NO2 is 99.0%and 98.0%. |
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