传质控制下宽分布石膏颗粒群溶解特性

Dissolution characteristic of gypsum particles with wide size distribution under mass transfer controlling

烟气CO_2直接与工业固废磷石膏矿化反应生成碳酸钙与硫酸铵的控速步骤是磷石膏的溶解。在传质控制下,准确表达溶解特性是矿化反应器设计的理论依据。采用种群平衡模型预测传质控制下粒径宽分布石膏颗粒群溶解特性,采用矩积分法和特征线法对模型进行数值求解并与传统的平均粒径模型表达进行对比。结果显示:种群平衡模型反映了粒径分布对溶解速率的影响,计算得到溶解过程中总容积传质系数的变化,与实验结果吻合良好,证实了种群平衡模型预测的可靠性。与之相比,平均粒径模型预测溶解速率值比实验值偏大,由此解释了工业反应器中物料实际停留时间大于模型计算值的原因。

The rate-control step of the direct reaction of flue gas CO2 with industrial solid waste phosphogypsum mineralization to form calcium carbonate and ammonium sulfate is the dissolution of phosphogypsum.Expressing exactly the dissolution characteristics provides theory basis for designing mineralize reactor under mass transfer controlling.In this study,the dissolution characteristics of gypsum particles which had wide size distribution were predicted through population balance model.The results were compared with classical average size model showed the influence of size distribution on dissolution rate.The variation of total volumetric mass transfer coefficient was calculated and in agreement with the experimental data to confirm the reliability of population balance model.In contrast,the average particle size model predicts that the dissolution rate value is larger than the experimental value,thereby explaining why the actual residence time of the material in the industrial reactor is greater than the calculated value of the model.