石灰石和白云石高温循环脱除CO_2过程分析

Process analysis of cyclic CO_2 capture using limestone and dolomite at high temperature

在N2气氛和高浓度CO2气氛两种典型煅烧气氛下,对石灰石和白云石在循环煅烧/碳酸化捕集CO2过程中的主要系统参数包括长周期循环碳酸化转化率、平均碳酸化转化率、CO2捕集效率和煅烧炉能量需求进行了实验研究和计算分析。结果表明,吸收剂补充流率和吸收剂循环流率对平均碳酸化转化率、CO2捕集效率和煅烧炉所需能量具有直接影响。在相同吸收剂补充流率和循环流率条件下,采用白云石时的平均碳酸化转化率、CO2捕集效率均高于采用石灰石时;在CO2捕集效率为95%和相同煅烧气氛时,采用白云石的煅烧炉所需最小能量至少比石灰石节省82 kJ.(mol CO2)-1。与N2气煅烧气氛相比,在高浓度CO2煅烧气氛下得到的吸收剂平均碳酸化转化率、CO2捕集效率均下降,煅烧炉所需最小能量增加,但采用白云石时主要系统参数的变化均小于石灰石。

The main system parameters,including long-term cyclic carbonation conversion,average carbonation conversion,CO2 capture efficiency and energy requirement for a calciner in the two kinds of typical calcination atmospheres,including pure N2 and high concentration CO2 were investigated by experiment and calculation during the cyclic calcination/carbonation process for CO2 capture using limestone and dolomite.The results showed that fresh sorbent flow ratio and recycled sorbent flow ratio had direct effect on average carbonation conversion,CO2 capture efficiency and energy requirement for the calciner.For the same fresh sorbent and recycled sorbent flow ratios,dolomite exhibited greater average carbonation conversion and CO2 capture efficiency than limestone.At CO2 capture efficiency of 95% and in the same calcination atmosphere,at least 82 kJ·（mol CO2）-1 was saved in the minimum energy requirement for the calciner using dolomite than that using limestone.Compared with the results in pure N2 calcination atmosphere,the two sorbents both showed a decrease in average carbonation conversion and CO2 capture efficiency for the sorbents and exhibited an increase in minimum energy requirement for the calciner in high concentration CO2 atmosphere,however,the changes of these main system parameters for dolomite were less than those for limestone.