生物质燃烧烟气中含K成分生成颗粒物的模拟研究

Modeling on Transforming Behavior and Process of K-containing Species into Particles in Flue Gas from Biomass Combustion

采用一维柱塞流反应器数学模型描述生物质燃烧烟气中含K成分转化生成亚微米颗粒的过程和行为,研究了纯KCl气体生成颗粒物的行为,并研究了 K2SO4颗粒存在和KCl硫酸盐化反应对KCl气体向颗粒物转化的影响。研究结果表明:纯KCl气体在700 ℃左右开始成核,增大冷却速率和减小初始KCl气体体积分数会增大所形成颗粒数浓度、减小颗粒尺寸;一定数浓度的K2SO4颗粒的存在会抑制KCl气体的均相成核;含KCl、SO2、O2和H2O的烟气系统中KCl通过硫酸盐化反应形成K2SO4,其成核形成的颗粒物会抑制KCl气体的均相成核而使其以异相凝结形式向颗粒物转化。

A mathematic model of plug flow reactor was applied to describe the transforming process and behavior of K-containing species into submicron particles in the flue gas from biomass combustion, while a research was conducted on the following aspects, such as the transforming behavior of pure KCl gas into submicron particles, and the influence of the presence of K2SO4 particles and the sulfation of KCl on the transformation of KCl from gas state into solid particles, etc. Research results show that the starting temperature of the homogeneous nucleation of pure KCl gas is approximately 700 ℃, and with the rise of cooling rate and the decrease of initial volume fraction of KCl gas, the number concentration of KCl particles increases and the average particle size decreases. The homogeneous nucleation of KCl gas may be suppressed by the presence of K2SO4 particles at a certain number concentration. In the flue gas containing KCl, SO2, O2 and H2O, the KCl would convert into K2SO4 through sulfation, and the particles formed by nucleation would suppress the nucleation but drive the condensation of KCl gas into submicron particles.