火电厂石膏旋流器空气柱特性及结构优化研究

发布时间：2018-05-25 14:13

本文选题：旋流器 + 分股比　；参考：《华北电力大学》2014年博士论文

【摘要】：石膏旋流器是火电厂石灰石-石膏湿法烟气脱硫系统的重要设备,主要作用是对吸收塔中脱硫反应的副产物石膏浆液进行浓缩和分级,经真空皮带机脱水后生成的脱硫石膏广泛应用于水泥、建筑等领域。石膏旋流器在实际生产过程中存在底流夹细、分级效果不理想等问题,不仅干扰整个脱硫系统的正常运行,还会影响生成石膏的品质。因此正确认识旋流器内部的流动特性,设计高效节能的石膏旋流器具有重要意义。本文阐述了旋流器内流场的流动特性,对不同排口比的石膏旋流器进行性能实验,得到了分股比、底流浆液密度、底流排出方式、底流含固量等参数的变化规律,拟合得出分股比与排口比之间的关系式,并对排口比在0.3～1之间时,石膏旋流器的分级效率曲线进行了比较,分析了底流夹细现象的产生原因。利用Fluent软件,选取RSM雷诺应力模型与VOF流体体积模型,对固液旋流器中的重要现象——空气柱进行了数值模拟,包括其形成的整个过程、外观形状、三维速度场随时间、空间的变化,分析了空气柱对旋流器工作性能、能耗的影响,得到了空气柱直径随入口速度、溢流管与底流管直径以及介质密度的变化规律。基于空气柱带来的负面影响,设计倒锥形中心棒并选择合理的安装方式。对插入不同结构尺寸中心棒的石膏旋流器进行性能实验,得到入口压强、生产能力、底流与溢流浆液特性参数的变化情况,分析了中心棒对旋流器分级性能的影响,并以某4×600MW火电厂石膏旋流器的石膏生产情况为基础,通过计算得到了中心棒对整个实验系统的节能效果。为提高石膏旋流器的分级性能,设计具有分离块和隔板的新型旋流器入口结构。采用DPM离散相模型,对不同粒径石膏颗粒在新型入口中的运动情况进行数值模拟,分析了入口结构与入口速度对颗粒运动的影响,并对具有新型入口结构的石膏旋流器进行性能实验,得到了入口结构对指标参数的影响,通过分级效率曲线反映出该入口结构对中等粒度石膏颗粒的分级效率有明显的提高。
[Abstract]:Gypsum cyclone is an important equipment of limestone gypsum wet flue gas desulfurization system in thermal power plant. The main function is to concentrate and classify gypsum slurry which is the by-product of desulfurization reaction in absorber. Desulphurized gypsum produced by dehydration of vacuum belt machine is widely used in cement, building and so on. In the actual production process of gypsum cyclone there are some problems such as fine bottom current clip and unsatisfactory classification effect which not only interfere with the normal operation of the whole desulfurization system but also affect the quality of gypsum formation. Therefore, it is of great significance to correctly understand the internal flow characteristics of hydrocyclone and design high efficiency and energy saving gypsum hydrocyclone. In this paper, the flow characteristics of the flow field in the hydrocyclone are described. The performance experiments of the gypsum cyclone with different discharge ratios are carried out, and the variation rules of the parameters such as the split ratio, the bottom flow slurry density, the bottom flow discharge mode and the bottom flow solid content are obtained. The relationship between split ratio and outlet ratio is obtained by fitting, and the classification efficiency curve of gypsum cyclone is compared when the discharge ratio is between 0.3 and 1, and the causes of the phenomenon of bottom flow clamping are analyzed. Using Fluent software, RSM Reynolds stress model and VOF fluid volume model are selected to simulate the air column, which is an important phenomenon in solid-liquid cyclone, including the whole process of its formation, appearance shape, and three-dimensional velocity field with time. The influence of air column on the performance and energy consumption of hydrocyclone is analyzed. The variation of air column diameter with inlet velocity, overflow tube and bottom flow tube diameter and medium density is obtained. Based on the negative effects of the air column, the inverted conical center rod is designed and the proper installation mode is chosen. The performance experiment of gypsum hydrocyclone with different structure size is carried out, and the change of inlet pressure, production capacity, bottom flow and overflow slurry characteristic parameters is obtained, and the influence of center rod on the classification performance of cyclone is analyzed. Based on the gypsum production of a 4 脳 600MW thermal power plant gypsum cyclone, the energy saving effect of the central rod on the whole experimental system is obtained by calculation. In order to improve the classification performance of gypsum hydrocyclone, a new type of inlet structure with separating block and partition board is designed. The DPM discrete phase model was used to simulate the movement of gypsum particles with different particle sizes in the new inlet. The effects of inlet structure and inlet velocity on the movement of the particles were analyzed. The influence of the inlet structure on the index parameters is obtained through the performance experiments of the gypsum cyclone with a new type of inlet structure. The classification efficiency of the inlet structure on the medium granularity gypsum particles is obviously improved by the classification efficiency curve.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：X773

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