CO2浓度对钙基CO2吸收剂循环反应动力学特性的影响

摘要

In order to analyze the effect of CO_2 concentration on kinetic characteristics of the cyclic reactions of Ca-based CO_2 sorbent,the cyclic reaction characteristics of limestone were investigated using the two-stage shrinking-core model.As the results indicate,the change of CO_2 concentration has great influence only on the chemical reaction controlling stage,but the product layer diffusion controlling stage is independent of CO_2 concentration.For single cycle,the increase of CO_2 concentration leads to the shortened time of the chemical reaction controlling stage and the increased apparent chemical reaction rate constant.For multiple cycles,the increase of CO_2 concentration leads to a trend that the apparent chemical reaction rate constant decreases quickly with the increase of cycle numbers.In addition,the CaO carbonation reaction has been saturated at 25% CO_2 concentration,so the further increase of CO_2 concentration can′t improve the final conversion rate.%为分析CO2浓度对钙基CO2吸收剂循环反应动力学特性的影响规律,利用两段的收缩核模型对石灰石循环反应特性进行了研究。结果表明：反应气氛中CO2浓度的变化只对化学反应控制阶段有较大影响,对产物层扩散控制阶段影响不明显。对于单次循环,CO2浓度的增大促使化学反应控制阶段结束时间缩短,表观化学反应速率常数增大;对于多次循环,CO2浓度的增大导致化学反应阶段表观反应速率常数随着循环次数的增加加速衰减。另外,CaO碳酸化反应在25%CO2浓度下已经饱和,继续增大CO2浓度不能提高最终转化率。