【作者】 王伟之；

【导师】 张书廷；

【作者基本信息】 天津大学 ， 环境工程， 2007， 博士

【摘要】 目前常用的烟气脱硫技术普遍存在着设备投资及运行成本高的问题,严重地制约了脱硫措施的实施。在对膜电解和钠碱脱硫法进行深入研究的基础上,本课题组开发了一种解决烟气脱硫问题的新工艺——低价态膜电解超声波协同钠碱再生循环烟气脱硫工艺。本文即以该工艺为背景,通过理论模型模拟与实验研究相结合的方法,研究了钠碱烟气脱硫吸收过程中的气液传质及反应特性。根据液相化学平衡原理对SO₂吸收过程分析计算得出吸收平衡时吸收液的脱硫容量及饱和pH与气相SO₂分压关系,明确了钠碱脱硫中吸收的极限条件参数;进一步以Na₂SO₃为吸收剂进行了填料塔内烟气脱硫模拟实验研究,重点考察了吸收液pH、液气比（L/G）、空塔气速、烟气中SO₂初始浓度、吸收液温度及吸收剂初始浓度等对脱硫率的影响。结果表明,脱硫率随吸收液pH、L/G和吸收剂浓度的增加而提高,随吸收液温度、烟气温度、进气SO₂浓度及空塔气速的升高而降低;其中pH值对脱硫效率影响很大;而当液气比L/G大于3L/m3时,对脱硫效率的影响幅度明显变小。基于双膜传质理论,建立了填料塔内钠碱脱硫中气液反应的数学模型,根据工艺研究中的实验条件对模型赋初值,结合模型参数确定适宜的边界条件后,采用MATLAB对模型方程进行求解,得到了液膜内各组分的浓度分布曲线,以及气相分压、pH值、传质阻力、传质速率及吸收增强因子等沿塔高的分布特性。按化学吸收速率计算方法得出钠碱脱硫吸收塔中填料层高度的计算公式,经验证后,以钠碱脱硫系统中吸收塔的工业设计为例,针对工业烟气脱硫中化学吸收塔提出了完整的设计程序。本论文通过对钠碱脱硫吸收过程的气液反应特性进行系统研究,掌握了填料塔内钠碱溶液吸收烟气中低浓度SO₂的操作特性及其气液反应及传质规律,为推广低价态膜电解超声波协同钠碱再生循环烟气脱硫工艺这一湿法烟气脱硫技术提供了有价值的设计依据和理论指导,本研究也可为其它钠碱法脱硫工艺中实现低成本、高效率的吸收提供有益的参考。更多还原

【Abstract】 Due to the high capital cost and the lack of technology support, the study of desulfurization in China is left behind. A novel wet FGD （Flue Gas Desulfurization） process is presented on the base of study of sodium alkali FGD and membrane electrolysis, which utilizing traditional ion-exchange membrane electrolysis and ultrasonic to regenerate sodium alkali fertile liquor and to reclaim sulfur dioxide as sulfuric acid. The absorption of SO₂ into sodium alkali solutioh is one of the key technics in the FGD technology. So in the thesis gas-giquid mass transfer and reaction characteristic of SO₂ absorption process in sodium alkali FGD was systematically investigated by both simulation and experiment.Based on the chemical equilibrium theory in liquid, the relationship between saturated pH of sodium alkaline solution, desulfurization capacity and partial pressure of SO₂ was obtained,which definitudes the ultimate parameters of absorption. Further the sodium alkali（Na₂SO₃） FGD process in a packing column was studied experimentally. Main parameters affecting SO₂ removal efficiency were studied for this process. These parameters include pH value of the absorption solution, liquid-gas ratio, superficial gas speed, inlet SO₂ concentration, temperature of absorption solution and initial Na₂SO₃ molar concentration. The experimental results show that SO₂ removal efficiency may be improved with the increase of pH,liquid-gas ratio and Na₂SO₃ molar concentration.And it may be dropped with the increase of other operating conditions. The effect of pH on the desulfurization efficiency is more obvious and the influence of L/G is not significant while L/G is more than 3L/m³.Based on the two-film mass transfer theory, a model for SO₂ absorption into Na₂SO₃ solution was put forward and established. The model was validated using experimental conditions in packed column. The equations in the model could be solved using MATLAB with boundary conditions obtained by rational estimation of the parameters involved. Then the solution of the model was used to calculate concentration profiles in the liquid film, SO₂ partial pressure, mass transfer rate, pH profiles, enhancement factor and individual resistances along the column. The calculated results were compared to experimental data and a good agreement was achieved.The formula to caculate the tower height of packed column in sodium alkali FGD was advanced based on the rate of chemical absorption. Making use of the method the optimized design of packed column in industrial FGD process was stated. Thus an integrated design process to the industrial chemical absorber in FGD was summarized in the paper.The results described the mass transfer-reaction mechanism and operating parameters characteristic of SO₂ absorption into Na₂SO₃ solution in packed column. The study in this paper provide a basic study for theoretical analysis and engineering design of the process of SO₂ absorption into sodium alkali solution and other wet FGD process, which is very inportant to the practical application of desulfuriation equipments.更多还原