SCR烟气脱硝技术SO_2催化反应动力学机理分析

Mechanism analysis on SO_2 catalytic reaction kinetics of power of SCR

SCR烟气脱硝中的V_2O_5/AC催化剂能使SO_2反应生成SO_3,而其生成的SO_3与NH_3反应的产物会对空预器造成严重的破坏。为了揭示SO_3与NH_3的反应机理,进而减弱SO_3与NH_3的反应,建立了H2O-SO3和H2SO4-NH3反应动力学模型。通过模型计算,分析了H_2O-SO_3和H_2SO_4-NH_3的反应吉布斯自由能、反应速率常数,以及反应温度对反应速率的影响。模拟结果表明:温度在550K^800K的范围内,H_2O-SO_3和H_2SO_4-NH_3反应能自发进行,且为不可逆反应;在相同的氮硫比、反应温度的条件下,H_2O-SO_3和H_2SO_4-NH_3的反应速率常数逐渐变大,反应温度的升高对于H_2O-SO_3和H_2SO_4-NH_3反应的影响明显。因此在SCR脱硝过程中要抑制(NH_4)_2SO_4或是NH_4HSO_4的生成最关键部分是抑制SO_3的生成。

Reaction of SO2 into SO3 by V2O5/AC catalyst for denitrification technique and the product of SO3 and NH3 can cause serious damage to the air preheater. It established the reaction kinetic models of H2SO4-NH4 and SO3 - H2O in order to reduce reaction of SO3 and NH3. And the accuracy of the model was analysis the Gibbs energy and reaction rate constant of H2SO4 - NH,and SO3 - H2O, and impacting on chemistry rate of temperature. The modeling result demonstrates that H3 SO4 -NH3 and SO3-H2O spontaneous reaction and reversible reaction to a large extent equilibration when the temperature ranges between 550K and 800K. H2SO4, NH3 and SO3-H2O was reaction on similarity concentration and temperature condition that reaction rate constant was gradually becomes smaller. Improving to reaction temperature was obvious influence to reaction rate constant of H2SO4 -NH3 and SO3 -H2O. According to this result indicated that if we want to reduce production of （NH4 ）2SO4 and NH4HSO4, we should be strictly controlled SO3 by the press of SCR denitrification.