湿法脱硫塔一维传热传质性能模型理论与试验

Experimental and theoretical studies on 1-D model of heat and mass transfer performance for wet flue gas desulfurization scrubber

为预测湿法脱硫系统(wet flue gas desulfurization,WFGD)浆液温度,提出湿烟气绝热饱和温度的概念,推导浆液温度与入口烟气温度及含湿量的函数关系。基于预测的浆液温度,建立脱硫塔内液滴运动、热质传递及压差分布一维耦合数学模型;分析脱硫系统三维不均匀性对于模型准确度的影响;用龙格-库塔法对模型进行迭代求解,探讨脱硫塔内主要运行变量(浆液颗粒直径、烟气入口温度及液气比)对传热传质的影响,获得相关参数的一维分布规律。为验证模型的正确性,分别进行现场测试和物模试验。结果表明,预测的浆液温度与现场实测温度有较好的一致性,最大相对误差为4.56%;浆液颗粒直径是影响传热传质的主要因素;颗粒在下降过程中速度迅速衰减,并趋向于最终不变值;烟气温度沿塔高呈指数规律分布。与模型预测温度及压力相比,物模试验温度分布与压力分布的最大相对误差分别为4.72%和6.46%。模型具有较高的准确度,对脱硫塔的设计、运行及SO2的传质研究有指导意义。

To predict the slurry temperature in wet flue gas desulfurization(WFGD)system,a concept of insulation saturation temperature of wet flue gas was put forward,and the functional relationship between slurry temperature and inlet flue gas temperature and moisture content was deduced.Based on the predicted slurry temperature,a 1-D coupled mathematical model of droplets motion,heat and mass transfer and pressure loss of liquid-gas two phases was established,the influence of three-dimensional inhomogeneity of desulfurization system on model accuracy was analyzed.In terms of the main operating variables in desulfurization system(diameter of slurry particle,inlet temperature of flue gas and ratio of liquid to gas),the 1-D distribution law of the related parameters was obtained by the Runge-Kutta iteration method.In order to verify the model,the field test and physical model test were carried out respectively.The results showed that the predicted slurry temperature was in good agreement with the measured parameters,the maximum error was 4.56%;the diameter of slurry particle was the main factor affecting heat and mass transfer;the velocity of particles decayed rapidly in the process of decline,and tended to the final invariant value;the temperature of the flue gas was distributed exponentially with the height of the tower.Compared with the predicted values,the maximum errors of temperature and pressure distribution from the experimental results were 4.72%and 6.46%respectively.The model had high accuracy,which was of guiding significance to the design,operation and study on mass transfer of SO2 in WFGD system.