碱性吸收剂喷射脱除电厂烟气SO3技术及理论模型

碱性吸收剂喷射技术是一种高效脱除电厂烟气中SO₃的新型技术。为推动国内燃煤电厂烟气SO₃脱除技术的发展，介绍了该技术的特点、系统运行特征和原理，建立了SO₃脱除反应理论模型，并对理论模型进行了实践验证。此外，对加入的碱性吸收剂是否会影响脱硝催化剂的活性进行了论证。研究结果表明：（1）碱性吸收剂颗粒终端沉降速度在0.01~0.10m/s之间，远远小于烟气速度；（2）通过简化气固反应模型得到的理论SO₃脱除效率解析解，与工程实测值偏差在 ±5%以内；（3）SO₃脱除效率与烟气速度、烟气温度，吸收剂颗粒粒径、吸收剂与SO₃摩尔比等因素相关；（4）在工程设计过程中，将吸收剂与SO₃摩尔比设置在1.5以上，吸收剂粒径选择在30μm以下，吸收剂颗粒停留时间不小于4s，可保证SO₃脱除效率在80%以上；（5）碱基吸收剂亚硫酸钠对脱硝催化剂的负面影响可忽略不计。

Theoretical Model for SO3 Removal from Flue Gas Using Alkali Sorbent Injection Technology in Power Plant

Alkaline sorbent injection is a new technology to remove SO₃ from flue gas in power plant. In this paper, the technical features, system operation characteristics and principles of SO₃ removal using alkaline absorbent are introduced. Meanwhile, the theoretical model of SO₃ removal reaction is established and verified through practice. Moreover, the impact of alkaline sorbent on the activity of catalyst is examined. The results show that the terminal settling velocity of absorbent is 0.01~0.1m/s, which is far less than that of flue gas. By simplifying the gas-solid reaction model, the deviation of theoretical SO₃ removal efficiency from engineering measurement value is less than ±5%, and the SO₃ removal efficiency is related to the flue gas velocity, flue gas temperature, particle size, chemical equivalence ratio and so on. In the process of engineering design, in order to ensure the SO₃ removal efficiency above 80%, the stoichiometric ratio must be set higher than 1.5, and the particle size of absorbent must be smaller than 30 μm, while the retention time of absorbent particles should not be less than 4s. The side effects of sorbent sodium sulfite on denitration catalysts is negligible.