造纸白泥循环碳酸化/煅烧捕集CO_2后的硫酸化特性

Sulfation Behavior of White Mud from Paper Mill after Carbonation/Calcination Cycles

在热重仪上研究了经历不同碳酸化/煅烧循环反应后白泥的硫酸化特性、微观结构及硫酸化反应动力学.结果表明,在典型循环流化床锅炉温度范围内(850～950℃),提高反应温度有利于循环碳酸化/煅烧后白泥的硫酸化反应,但对于100次循环反应后的白泥,温度对其硫酸化转化率影响不大.未循环白泥取得了最高硫酸化转化率,此后随着碳酸化/煅烧循环次数增加,硫酸化转化率衰减,但50次循环后白泥取得了更高的硫酸化转化率,高于15次和100次循环后的转化率.这与白泥在循环碳酸化/煅烧中的孔隙结构有关.碳酸化/煅烧循环次数对白泥硫酸化时的活化能有较大影响.经历了不同循环次数的白泥,在硫酸化时化学反应活化能介于15～50kJ/mol之间,而产物层扩散活化能则介于40～168kJ/mol之间.

The sulfation behavior, microstrucmre and sulfation kinetics of white mud after various carbona- tion/calcination cycles were investigated in a thermo-gravimetric analyzer. The results show that at the typical CFB boiler temperatures （850--950 ℃）, higher sulfation temperature is beneficial for the sulfation of white mud after various carbonation/calcination cycles. However, the effect of sulfation temperature on the sulfation conversion of white mud after 100 cycles is little. The uncycled white mud achieves the highest sulfation conversion. The sulfation conversion of white mud decreases with the increase of the number of cycles, but it achieves a higher conversion after 50 cycles, which is greater than that after 15 and 100 cycles. The sulfation behavior of white mud after various cycles is related to pore structure. The carbonation/calcination cycle number has an important effect on the activation energy for sulfation of white mud. The chemical reaction activation energy for sulfation of white mud after various carbonation/calcination cycles is within the range of 15--50 kJ/mol, and the activation energy for product layer diffu- sion is within the range of 40--168 kJ/mol.