模拟烟气碳化绿液脱硅固碳及对白泥品质的影响

Simulated flue gas carbonization green liquid desilication and carbon fixation and its impact on white mud quality

为了解决蔗渣浆白泥硅含量高、品质差,影响下游利用的难题,同时减少锅炉烟气CO_(2)释放,利用CO_(2)和空气混合模拟锅炉烟气对蔗渣浆绿液进行酸化脱硅固碳处理,并对脱硅后绿液进行苛化反应.结果表明:在反应温度为80℃、时间为6h、通气速率为500 L·L^(-1)·h^(-1)(CO_(2)体积分数为10%)、膨润土加入量为0.15g/L的条件下,绿液脱硅效率为75.34%±2.74%.脱硅后绿液苛化率提高4.5%以上,但氧化钙耗量增加约20%,苛化生成的白泥中碳酸钙质量分数由89.49%提高到98.80%,SiO_(2)质量分数由2.63%下降至0.63%,同时镁、硅、氯、水溶性盐等杂质含量均有所下降,显著改善了白泥品质.蔗渣浆绿液的理论固碳潜力为25.69 kg/m^(3),吨纸浆所产生的绿液固碳量占锅炉烟气碳释放量4.46%;实际固碳量为15.47 kg/m^(3),占锅炉烟气碳释放量2.68%.

To solve the problem of high silica content and poor quality of bagasse pulp white mud,which could affect the downstream utilization,and at the same time to reduce the release of CO_(2) from the boiler flue gas,the acidification desilication and carbon fixation of bagasse pulp green liquor was carried out by using a mixture of CO_(2) and air to simulate the boiler flue gas,and the causticizing reaction was carried out on the desiliconized green liquor.Results show that the desilication efficiency of green liquor is 75.34%±2.74% under the conditions of reaction temperature of 80℃,time of 6 h,aeration rate of 500 L·L^(-1)·h^(-1)(CO_(2) volume fraction of 10%) and bentonite addition of 0.15 g·L^(-1).After desilication,the causticizing rate of green liquor increases by more than4.5%,but the consumption of calcium oxide increases by about 20%.The mass fraction of calcium carbonate in the white sludge produced by causticizing increases from 89.49% to 98.80%,the mass fraction of SiO_(2) decreases from 2.63% to 0.63%,and meanwhile the contents of magnesium,silica,chlorine,water-soluble salts and other impurities all decrease,improving the quality of white sludge.The theoretical carbon sequestration potential of bagasse pulp green liquor is 25.69 kg/m^(3),and the carbon sequestration of green liquor produced by tons of pulp accounts for 4.46% of carbon release from boiler flue gas;the actual carbon sequestration is 15.47 kg/m^(3),accounting for 2.68% of carbon release from boiler flue gas.