CFB炉内脱硫石灰石的粒径分布及热分解行为

Particle Size Distribution and Thermal Decomposition Behavior of Limestone for Desulfurization of CFB

基于流态化理论和脱硫机理,对破碎后的入炉石灰石、运行过程中的循环灰和飞灰进行粒径分析,得出粒径小于0.088mm的石灰石较难被旋风分离器有效捕捉,容易发生扬析,从而造成脱硫剂的浪费.采用热重分析方法和Coats-Redfern近似法重点研究粒径为0.088 mm～2.500mm石灰石的热分解特性和动力学.结果表明:粒径增大不利于石灰石分解反应的进行,粒径为0.088mm～0.450mm的石灰石具有较好的热分解特性;分解动力学结果表明,由粒径变化引起的石灰石颗粒内外温度变化对活化能无明显影响,但会对频率因子产生影响,这可能与小粒径增加了颗粒的比表面积有关.

Based on the fluidization theory and desulfurization mechanism,particle size analysis was taken to the crushed limestone in the furnace,the circulating ash and fly ash during operation.The results show that limestone of particle size less than 0.088 mm is difficult to be effectively captured by cyclone,which will be prone to elutriate and cause waste of desulfurizer.The thermogravimetric analysis method and Coats-Redfern approximate method are taken for a further study of decomposition characteristics and kinetics of limestone of 0.088 mm-2.500 mm particles.The results show that the increase of particle size is not conducive to the decomposition reaction of limestone,and limestone of 0.088 mm-0.450 mm particle size has better thermal decomposition characteristics.The kinetic curve fitting results show that activation energy do not change significantly with the decrease of the particle size,and frequency factor increase with the decrease of particle size.When the particle size decreases to a certain value,frequency factor begins to decrease.This may be related to the surface microstructure of limestone.