旋转填充床内硫酸铵溶液脱除二氧化硫的数值模拟

Model of sulfur dioxide removal by ammonia-based solution in rotating packed bed

为降低现有设备在处理二氧化硫过程中存在费用昂贵而且操作困难的问题,遂开发旋转填充床。为进一步揭示其内部的复杂现象及放大过程,通过考虑化学反应、气液传质、持液量和有效比表面积等,建立旋转填充床中硫酸铵溶液脱除二氧化硫的数学模型。模型经过试验验证后,进一步优化超重力因子、液体流率、气体流率、入口质量浓度以及吸收剂浓度,以期得到较高的脱硫效率。结果表明,模型可以很好地描述旋转填充床中的二氧化硫脱除过程。

To further reduce the cost of equipment in the traditional sulfur dioxide removal process and meet the ultra-low emissionstandard, a rotating packed bed(RPB) was developed. Because of the complex sulfur dioxide removal process by ammonium sulfate in the RPB, a theoretical model was developed to support its industrialization. The model was a one-dimensional steady-state, including the mass balance of sulfur dioxide in the gas and liquid phase, gas-liquid mass transfer, and chemical reaction. The unique characteristics in the RPB were also included, such as gas-liquid mass transfer rate, liquid holdup, gas-liquid effective area, etc. These characteristics were greatly enhanced by the rotating packing. After verified by the experimental results, the model was used to optimize the operation conditions.The simulated removal rate can be as high as 97.8% at a high gravity factor of 242.2, liquid flow rate of 340 L/h, the gas flow rate of 115 m^(3)/h, initial sulfur dioxide concentration of 900 mg/m^(3) and absorbent concentration of 0.69 mol/L. With the increase of high gravity factor, liquid flow rate and absorbent concentration, the decrease of gas flow rate and initial sulfur dioxide concentration, the simulated removal rate increases. The factors of turbulent extent, liquid dispersion degree, renew rate and contact opportunity, contact time between absorbent and sulfur dioxide and liquid holdup have much influence on the removal rate. The high gravity factor mainly affects mass transfer rate and efficiency area. The liquid flow rate mainly affects liquid mass transfer rate and liquid holdup. The gas flow rate mainly affects the gas mass transfer rate. The initial sulfur dioxide concentrationand absorbent concentration mainly affect the reaction rate. The deviations between the experimental results and the model data may be due to the use of correlations of gas-liquid mass transfer rate, liquid holdup, and gas-liquid effective area which are not fully the same as those of the experiment.