摘要
采用热分析法研究了贝壳和石灰石固硫反应过程，用等效粒子模型对固硫反应过程进行了表征，计算分析了其固硫反应动力学参数．结果表明，贝壳比石灰石含有较多的碱金属盐，其作用是提高了贝壳固硫反应速率常数和有效扩散系数．贝壳固硫反应中存在补偿效应．根据等动力学温度判别固硫剂活性适用于不同反应控制区的活性判断．碱金属成分对钙基固硫剂活性有正负两个方面的影响，含量过大或过小都会削弱固硫剂活性，因而存在最适含量．在1073—1273K温区固硫时，钙基固硫剂中碱金属离子与钙离子摩尔比为1：50左右时固硫活性较高．
The general desulfurization sorbent, limestone is limited in sulfation temperature range and suffers from rapid loss of reactivity and incomplete utilization. However, plentiful shells are generally abandoned as garbage especially in coastal area, which consist of CaCO3 similar to limestone. Desulfurization with shell shows a higher calcium utilization and better sulfation property than limestone under various experimental conditions. The desulfurization reaction process of calcium-based sorbent including four species of shell and a sort of limestone were investigated by thermogravimetric analysis method. The kinetic behavior was expressed by the modified grain model. The activation energy （ Ea ） and the pre-exponential factor （ k0 ） of surface reaction, the activation energy （ Ep ） and the pre-exponential factor （ D0） of product layer diffusion reaction were calculated and explained according to the model. It is shown that the modified grain model can describe the desulfurization course of shells and limestone. Additions of alkali metal salts may improve microstructure and product diffusion of sorbent during high temperature sulfation, and enhance the initial reaction rate and the final CaO conversion of sorhents. The kinetic parameters of shell desulfurization show a compensation effect. There are linear relationships between logarithms of the pre-exponential factor Ink0, InD0 and activation energies Ea, Ep respectively. The method based on the isokinetic temperature T, to estimate sorbent activity is applied to different control stage. Alkali metal salts can enhance the initial reaction rate, at the same time can accelerate the high temperature sintering of sorbent, so there is optimal content in sorbent. The advisable molar ratio of alkali metal cations （mainly Na^＋ and K^＋ ） to Ca^2＋ in the sorbent is best kept to 2% approximately at the desulfurization temperature range of 1 073 -1 273 K.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第2期327-331,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:59976019)
山东省自然科学基金(批准号:Y2003F07)资助
关键词
固硫
动力学
钙基固硫剂
补偿效应
贝壳
Desulfurization
Kinetics
Calcium-based sorbent
Compensation effect
Shell
