SO2对钙基CO2吸收剂循环煅烧/碳酸化反应的影响

在循环煅烧/碳酸化反应系统中,研究了SO₂对钙基吸收剂CaCO₃捕集CO₂的影响,获得了SO₂对钙基吸收剂碳酸化特性、煅烧特性以及循环稳定性的影响规律,并结合SEM分析结果,从循环煅烧/碳酸化反应角度,分析了可能存在的原因。结果表明,钙基吸收剂吸收CO₂的能力随着循环反应次数的增加逐渐发生衰减,在SO₂影响下,这种衰减会进一步加剧,且衰减程度随着SO₂浓度的增加而增大,经过十次循环后,碳酸化转化率分别为25.5%(0%SO₂)、16.9%(0.1%SO₂)和5.2%(0.2%SO₂)。造成这种衰减加剧的主要原因是反应产生较厚的硫酸化产物层,硫酸化产物层使颗粒表面孔隙发生堵塞,阻碍了CO₂在吸收剂内部的扩散,降低了碳酸化转化率。

Influence of SO2 on the cyclic calcination and carbonation of calcium-based sorbent for CO2 capture

The effects of SO₂ on the cyclic calcination and carbonation characteristics and the cycling stability of calcium-based CaCO₃ sorbent for CO₂ capture were investigated in a cycling calcination/carbonation system. The results indicated that the capacity of CaCO₃ sorbent for CO₂ capture decreases with the increase of the number of calcination/carbonation cycling and the addition of SO₂ will further reduce the capacity for CO₂ capture; moreover, the decrease of the capacity for CO₂ capture may be aggravated at higher SO₂ concentration. After 10th cycling, the carbonation conversions of the sorbent under SO₂ concentration of 0, 0.1% and 0.2% are 25.5%, 16.9% and 5.2%, respectively. SEM characterization results revealed that sulfate products are formed on the surface of CaCO₃ particles in the presence of SO₂; the sulfate products block the sorbent holes and then reduce the diffusion rate of CO₂ into the sorbent, which may then reduce the capacity of the calcium-based sorbent for CO₂ capture.