摘要
燃煤锅炉排放SO2控制技术有多种方式,最有效而得到广泛应用的是湿式石灰/石灰石—石膏法烟气脱硫技术。液柱喷射烟气脱硫技术就是其中先进的一种,其特点是气液交融强烈,运行稳定可靠,烟气脱硫效率高。本论文的研究内容是通过工程试验全面地研究液柱喷射烟气脱硫技术的性能及各种相关的影响因素,以期形成具有自主知识产权并能广泛应用到工程中的成套技术。
通过沈阳化肥总厂烟气脱硫示范工程的性能试验表明,液柱喷射烟气脱硫工艺操作稳定性好,可靠性高,适用于各种规模的入口烟气流量、各种入口烟气SO2浓度的烟气脱硫。影响脱硫装置性能的主要因素有:循环浆液的pH值、入口烟气SO2浓度、入口烟气流量和循环浆液量。而单位体积的循环浆液的脱硫能力可以用 来描述。同时在南宁和杭钢烟气脱硫项目的工程应用中,进一步证实了该式能够很好地描述液柱喷射烟气脱硫的性能,从而为今后的工程优化提供指导性的作用。
通过计算和工程试验表明,在连续运行的脱硫反应塔中,控制脱硫产物氧化速率的是O2的传质过程。而 F-、Cl-离子的大量存在将使脱硫效率下降10%左右;而通过△L定律对石膏的结晶过程建模可以很好地描述石膏结晶动力学过程;浆液沉降试验表明,浆液沉降较快,因此在浆液管道设计中应注意避免淤积堵塞。
为了进一步了解液柱喷射烟气脱硫的化学传质过程,本课题还对液柱喷射烟气脱硫反应塔内气液固三相脱硫反应传质过程进行了建模计算以及反应塔内气液两相流场的数值模拟工作。其中模型的计算结果与试验结果吻合较好,表明所建立的模型能很好地反映实际脱硫反应过程。而通过对工程应用中的脱硫反应塔内气液流场的数值模拟表明,在反应塔内气液分布均匀,气液交融很好,使得脱硫反应能够高效率地进行。
There are many control technologies of pollutant SO2 discharged by coal-fired boiler at the present time, including of wet lime/limestone-gypsum flue gas desulfurization(FGD), which is the most effective FGD technology and used in many fields. Slurry jet FGD is one of the advanced FGD technologies, charactered by strong gas-liquid turbulence mass transfer, credible operation and high-degree desulfurization. The target of this research is to study the overall performance of the slurry jet FGD technology and various influencing factors in pilot plant and other two application plants, with the aim to supply the complete FGD set with own knowledge property right.
Performance engineering tests in Shenyang fertilizer plant indicated that the slurry jet FGD technology operated stably and credibly, and can be applied to various FGD projects with difference flue gas flux and inlet SO2 concentration. The main influencing factors include: pH of recycled slurry, inlet SO2 concentration, inlet flue gas flux and recycled slurry flux. The desulfurization capability of per unit recycled slurry can be described by , which is confirmed by the application of slurry jet FGD technology to Nanning and Hangzhou FGD projects. So it can direct the optimization for the future projects.
Calculation and engineering tests in Shenyang, Nanning and Hangzhou FGD projects indicates that it is the O2 mass transport process which controls the oxidation rate of desulfurization product in consecutive operation of desulfurization tower. Other tests include: the presence of F- and Cl- ions in Hangzhou projects can reduce the desulfurization efficiency by about 10%. The gypsum crystallization kinetics process can be described by the gypsum crystallization model based on △L law. The slurry sedimentation tests indicates that the sedimentaton velocity of slurry is fast, so the attention must be applied to avoid silt and blockade in design of slurry ducts.
With the aim of more information of the chemical reactions and mass transport processes, the further investigations of a detailed model for slurry jet FGD pilot plant are developed. The calculate results accord with test results in pilot plant, which indicates that the model can well describe the desulfurizaiton processes in FGD tower. And the numerical simulation of gas-liquid two-phase flow field in FGD tower in pilot plant indicates that the two phases in tower are uniform distributing and well intermixed, which assures the high desulfurization efficiency in the FGD tower.
引文
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