Study On Kinetics And Processes Of Flue Gas Desulfurization By Ferric Sulfate In High Acidic Condition

Good sulfur removal efficiency had been achieved by the process of metal-catalyzed oxidation of sulfur dioxide in aqueous,while valuable byproduct polymeric ferric sulfate can be produced.It reduces costs by selling the high added-value byproduct,and no solid desulfurization product generated compared with traditional method.Study on kinetics and processes of flue gas desulfurization by ferric sulfate has been made,the aim to save the amount of oxidant,as well as good sulfur removal efficiency to be taken in this study.The main contents are as follows:Kinetics of Fe(â…¢) catalyzed oxidation of S(â…£) was studied by investigating the effects of ionic strength,concentration of Fe(â…¡),concentration of Fe(â…¢),temperature,pH on reaction rate.And the results showed that:little effect of ionic strength on reaction rate was observed when in high ferric concentration solution(C(Fe³⁺)≥0.6 mol/L).The reaction rate decreases quickly while a small amount of Fe(â…¡) exists in Fe(â…¢) solution.The reaction rate declined rapidly at higher Fe(â…¢) concentration.The reaction rate increases with the increasing of temperature.The appropriate pH value is 2.0 under certain conditions.The processes with ferric sulfate as absorbent to remove sulfur dioxide in flue gas in the packed absorption column and synthesize PFS with the absorption solution were investigated. The experiments showed that:pH value and Fe(â…¢) are two key factors to sulfur removal efficiency.Lower than 80%SO₂ removal efficiency had been observed when pH＜1.5, satisfied efficiency can be made when pH value was maintained 2.0 around.The SO₂ removal efficiency increases with higher Fe(â…¢) concentration,and 0.2 mol/L of Fe(â…¢) was thought to be moderate for the reason that much more NaOH would be used for adjusting the pH value of the solution when Fe(â…¢) was above 0.2 mol/L.Promotion effect of desulfurization by ferric-catalyzed oxidation was observed after continuing aeration,and the SO₂ removal efficiency increased as well.The optimal superficial gas velocity is 0.15 m/s.More than 90% SO₂ removal efficiency can be achieved when SO₂ concentration under 5700 mg/m³.SO₂ removal efficiency greater than 95%had been observed when liquid-gas ratio was maintained above 15 L/m³.little effect of temperature on SO₂ removal efficiency was observed when temperature was among 20～40℃.SO₂ removal efficiency was kept above 90%in the former 500 min in the continuous desulfurization experiment.Qualified liquid PFS product was produced by NaClO₃ oxidation method and 37.5%amount of oxidant theoretically was saved compared to the original process.