湿壁塔氨法烟气脱硫模型

摘要

近年来氨法脱硫以其低投入,脱硫率高以及有价值的副产物越来越受到重视.今以并流式湿壁塔脱硫实验装置为例,以氨水作为吸收液,在20℃和常压下研究了氨法烟气脱硫的气液传质与化学反应过程,并且在伴有快速的化学反应吸收的双膜理论的基础上,建立了数学模型.利用该模型对并流式湿壁塔氨法脱硫过程进行了模拟,分析了吸收液pH值、液气比、吸收液浓度、烟气流速以及初始SO2浓度对脱硫效率的影响,并与实验结果进行了对比.结果表明:在进气浓度为2500 mg·m-3时,最佳的工艺条件为液气比为2.2～2.8 L·m-3,吸收液pH值为5.8～6.5,烟气流速为1.5～2.5 m·s-1;该模型的计算值与实验数据基本吻合,为氨法烟气脱硫的工业化应用提供了理论参考.%Ammonia-based wet flue gas desulfurization has drawn increasing attention in China because of its lower investment, higher desulfurization efficiency and useful byproducts. A parallel flow falling film type wet desulphurization column with ammonia as absorbent was set up for studying the gas-liquid mass transfer and chemical reaction of the ammonia desulfurization process at 20℃C and atmospheric pressure. A mathematic model of ammonia desulphurization was established on the base of two-film theory of absorption with fast chemical reaction (the irreversible reaction of SO2 with (NH4)2SO3). Using the established model, the parallel flow falling film wet desulphurization process was simulated, and the factors affecting the desulphurization efficiency, such as the pH value of absorbent, liquid-gas ratio, concentration of absorbent, liquid gas flow rate and the initial SO2 concentration, were investigated. The results show that, when the inlet gas concentration of SO2 is 2500 mg·m-3, the optimal technical parameters are as follows: the liquid-gas ratio of 2.2 to 2.8 L·m-3, the absorbent pH value of 5.8 to 6.5, the flue gas velocity of 1.5 to 2.5 m·s-1. The calculated values agree well with the experimental data, and it indicates that the model established can provide a theoretical reference for the industrial process of ammonia-based flue gas desulphurization.