【作者】 赵英春；

【导师】 陈汇龙；

【作者基本信息】 江苏大学 ， 流体机械及工程， 2010， 硕士

【摘要】 湿钙法烟气脱硫因具有脱硫效率高、技术成熟等优势而成为烟气脱硫的主流技术,但该技术存在的喷淋量大、雾滴直径大、运行成本高等问题已是阻碍湿钙法烟气脱硫工艺在我国广泛应用的重要因素之一。石灰浆液荷电喷雾烟气脱硫是将静电喷雾技术应用于湿钙法烟气脱硫的一种新型脱硫方法,该法可以改善浆液雾化质量和SO2吸收条件,从而降低湿钙法烟气脱硫工艺的投资和运行成本。本文在研究荷电两相流及SO2吸收机理的基础上,对实验型石灰浆液荷电喷雾脱硫塔内的流场及SO2浓度场进行数值模拟,分析得到不同充电电压、浆液流量、气液流动方向时的流场和SO2浓度场特性,为石灰浆液荷电雾化脱硫技术的推广应用提供一定的理论基础。本文主要工作及结论如下：1.基于环状电极电位的拉普拉斯方程,通过对商用Fluent6.3计算功能的扩展,对环状电极感应静电场分布特性进行数值计算,结果表明：其电场强度对称分布,最高值出现在喷嘴附近,但离开电极后场强衰减迅速；随着电压的增加或电极间距的减小,电场强度增强,但喷嘴电极处比环状电极处增幅明显,是石灰浆液感应荷电的主要部位。2.采用Euler-Lagrange方法对石灰浆液荷电喷雾两相流场进行数值模拟,选择颗粒随机轨道模型对石灰浆液滴的运动进行追踪,通过Fluent 6.3中的UDF功能,编写并加载电场力应用程序,实现静电场与流场的耦合计算。结果表明：石灰浆液荷电后使烟气速度梯度在射流区内减小,且射流区边界附近烟气的卷吸作用加强,流量增加后这一影响更加明显,有利于烟气中SO2的吸收。3.利用Fluent 6.3中的UDF功能,对以双膜理论建立的SO2吸收模型进行程序编写并导入Fluent进行数值模拟,结果表明,SO2浓度分布与塔内两相流场特性紧密相关；石灰浆液荷电使脱硫效率增加；通过相同工况参数下的脱硫效果的比较可见,较大浆液流量时采取气液同向流动较好；计算脱硫率与实验测量值基本吻合,变化趋势一致。更多还原

【Abstract】 Wet flue gas desulphurization system has been the main technology among flue gas desulphurization industry in the world, as its high desulfurization degree and mature theory. But there are some problems discourage its wild application China, such as the large spraying quantity, the big size droplet and the high cost. Lime slurry charging spraying desulfurization is a new desulfurization method bringing electrostatic spraying into wet flue gas desulphurization system, with a lower investment and operating cost through atomization quantity and SO2 absorption situation improved.In this paper, numerical simulation for charged gas-liquid two phase flow field and SO2 concentration field in experimental lime slurry charging spraying desulfurization tower has been carried out, based on charged two phase flow theory and knowledge about SO2 absorption. From the result, it has been known the affection of charging voltage, slurry flow rate, injection direction and position on flow field and SO2 concentration field. This will make contribuition on extensive application of lime slurry charging spraying desulfurization.1. Electrostatic field generated by ring-like electrode has been simulated, based on Laplace equation, through extending commercial Fluent 6.3 function. The result shows that the electrostatic field is symmetry about z-axis, with the highest electrostatic field strength on nozzle, but electrostatic field strength is weakened quickly away from electrode; electrostatic field strength is strengthened as the charging voltage increased or the distension between electrodes decreased, while electrostatic field around nozzle electrode changes obviously, and it is the main part for lime slurry droplet induction charging.2. Charged two phase flow field in Lime slurry charging spraying desulfurization tower has been simulated based on Euler-Lagrange method, trajectories of lime slurry droplet using discrete random walk (DRW) model, and coupled simulation between electrostatic field and flow field has been achieved through adding electrostatic force procedure to computing process by UDF function in Fluent 6.3. The result shows gas velocity gradient decreases in jet flow zone after lime slurry charged, and gas entrainment is enhanced on bondary of the jet flow zone, which is obviously enhanced while the lime slurry flow rate increased, this will strengthen SO2 absorption process.3. SO2 absorption process has been simulated, adding SO2 absorption model through UDF function in Fluent, the result indicates that SO2 concentration is affected by the gas-liquid two phase flow field, and desulfurization degree calculated has a good agreement with the experimental data, while with the same tendency; desulfurization degree is increased as lime slurry charged; desulfurization performance is better when lime slurry injection and gas motion is in the same direction.更多还原