Abstract:

A new method to improve the CO₂ capture performance of carbide slag during the cyclic calcination/carbonation process by adding HCl intermittently(indirect chlorination) was proposed in this work. The effects of intermittent addition of HCl on the cyclic carbonation characteristics of carbide slag under different reaction conditions such as cycle number when HCl was added, carbonation temperature and volume ratio of CO₂/HCl were investigated in a dual fixed-bed reactor by adding HCl into carbonation atmosphere. The results showed that the CO₂ capture performance of carbide slag during the cyclic calcination/carbonation process can be improved by adding HCl intermittently during the carbonation. The optimum CO₂ capture performance of carbide slag was achieved when HCl was only added during the first 4 cycles and the CO₂ capture capacity after 10 cycles was 51% higher than that without addition of HCl. Chlorination happened between HCl and CaCO₃, which decreased CO₂ diffusion resistance through the compact product layer of CaCO₃, and thus higher carbonation conversion was obtained. The optimum carbonation temperature was still 700℃ in the presence of HCl. As the volume ratio of CO₂/HCl increased, the positive effect of HCl on the CO₂ capture performance of carbide slag decreased.

Key words: carbide slag, indirect chlorination, calcium looping, CO₂ capture

摘要：

提出在碳酸化气氛中间歇加入HCl（间歇氯化）提高电石渣在循环煅烧/碳酸化反应中捕集CO₂性能的新思路。在双固定床反应器上，在不同循环次数加入HCl、碳酸化温度、CO₂/HCl体积比等条件下，研究HCl间歇加入对电石渣循环碳酸化特性的影响。结果表明，在循环煅烧/碳酸化反应中间歇加入HCl使电石渣间歇氯化能提高其循环捕集CO₂性能。在前N次循环碳酸化时加入0.1% HCl，当N=4时能使电石渣获得最优CO₂捕集性能，第10个循环时的CO₂吸收量比无HCl时提高了51%。HCl与CaCO₃发生氯化反应，破坏致密产物层对CO₂扩散的阻碍，提高了电石渣的碳酸化转化率。在碳酸化气氛加入HCl时，最佳碳酸化温度仍为700℃。随CO₂/HCl体积比增大，HCl对电石渣捕集CO₂性能的促进作用减弱。

关键词: 电石渣, 间歇氯化, 钙循环, CO₂捕集