氨法脱硫烟气中气溶胶凝结脱除动力学

Dynamics of Aerosol Condensational Removal in Ammonia Desulfurization Process

针对氨法脱硫烟气中气溶胶的排放特性,建立氨法脱硫后细颗粒凝结长大脱除动力学模型,对细颗粒的凝结长大及脱除规律进行数值预测,并将其与实验结果进行比较。结果表明:细颗粒在过饱和蒸汽条件下迅速长大成液滴,在相同条件下,细颗粒初始数浓度越高,完成凝结长大的时间越短,液滴的最终粒径也越小;细颗粒脱除效率随停留时间增大迅速提高,在50～100ms内达到稳定,与理论计算值比,实验停留时间滞后,约在1.5s后脱除效率趋于稳定;脱硫后细颗粒凝结长大脱除效率与细颗粒物化性质有关,水洗涤时,当过饱和度高于1.4,细颗粒的脱除效率才随过饱和度的增大而迅速提高;氨法脱硫后,细颗粒可在较低的过饱和条件下凝结长大,因而脱除效率随过饱和度增大而提高。

A numerical model for the simulation of the aerosol condensational removal dynamics after ammonia desulfurization was proposed to predict the growth property of fine particles and removal efficiency. The simulation model was applicable for the aerosols discharge property of ammonia desulfurization. The results show that fine particles growth into droplets is very fast in a supersaturation vapor condition. Droplets complete growth time decrease and the final diameters of droplets are smaller at a higher initial particles number concentration. The removal efficiency of fine particles increases rapidly with the residence time, and achieves stability after 50-100 ms. Compared with the simulated values, experimental residence time appeares delate, which tend to stabilize at 1.5 s. Fine particles removal efficiency improved by condensational enlargement is dominated by the particles physicochemical characteristics after desulfurization. Removal efficiency increases with initial supersaturation degree rapidly only when the supersaturation degree higher than 1.4 with water scrubbing. However, condensational growth of fine particles is occurred at an extremely low supersaturation after ammonia desulfurization, and the removal efficiency increases with the supersatration degree continuously.