【作者】 李佳；

【导师】 杨历；

【作者基本信息】 河北工业大学 ， 热能工程， 2017， 硕士

【摘要】 人类生活环境正在被大量的细颗粒物充斥,它们不但严重影响着大气环境而且危害人体健康。研究表明,细颗粒危害的主要原因在于其体积小,数量大且现有的除尘设备难以脱除。因此,通过一定的物理、化学手段诱导细颗粒物长大为较大粒径颗粒后再进行常规脱除的预处理技术受到了更多的关注。考虑到目前烟煤电厂普遍采用湿法、半干法等烟气处理工艺,烟气具有较大的相对湿度。只需要少量蒸汽加入便能够使环境达到过饱和条件促进细颗粒物异质核化行为的发生,这为蒸汽相变团聚技术的实现创造了良好条件。此外,湍流团聚技术利用涡旋结构引导细颗粒物随涡聚集、碰撞团聚为较大粒径的颗粒,具有装置布局简单,运行成本低的特点,也受到了广泛的关注。本文对细颗粒物脱除技术和流体力学软件的相应模块进行了了解,并对比各种团聚技术以及模拟方法的优缺点。在总结前人对细颗粒物团聚技术研究的基础上,进一步对蒸汽相变团聚和湍流团聚进行深入研究。使用UDF编写了适用于蒸汽相变团聚技术的核函数,并将该技术与湍流团聚技术进行耦合计算。首先,建立了蒸汽相变团聚室,分析了蒸汽添加量、烟气温度对细颗粒物团聚的影响。结果表明,过饱和环境是发生异质核化的必要条件。添加蒸汽越多细颗粒物粒径增加效果越好。烟气与蒸汽温差越大,过饱和程度越高,细颗粒物粒径增长效果越显著。其次,对”|”字型和“C”字型两种扰流元件下细颗粒物的团聚以及团聚室压降效果进行了分析。结果表明,相比于“|”字型涡片,“C”字形涡片能产生对称涡旋结构,且出口大粒径颗粒的数密度较多且“C”字形涡片能够具有更小的压降水平。对“C”字型涡片的排列间距进行分析优化,选定了最佳涡片间距。最后,结合蒸汽相变以及湍流团聚技术,提出了一种新型相变团聚室。分析了新型相变团聚室的流场特点以及团聚效果,并将其与单纯湍流团聚效果进行分析,证实了新型团聚室具有较好的团聚效果。更多还原

【Abstract】 The human living environment is being flooded with a lot of fine particles,which not only seriously affect the atmospheric environment but also endanger human health.Studies have shown that the main reason for the harm of fine particles is that they are small in size and large in number,and the existing dust removing equipment is difficult to remove.Therefore,using certain physical or chemical means to induce fine particles grow larger particles and remove by the conventional pretreatment technology has received more attention.Taking into account the current widespread use of coal-fired power plant wet,semi-dry flue gas treatment process,the flue gas has a greater relative humidity.Only adding a small amount of ste am can create the supersaturated environment required for heterogeneous nucleation of fine particles,which creates favorable conditions for the realization of vapor phase-change agglomeration technology.In addition,the turbulent agglomeration technique uses the vortex structure to guide the fine particles to aggregate with the vortex and agglomerate into agglomeration particles with a larger particle size.The utility model has the advantages of simple device structure and low operation cost,and also attracts extensive attention.In this paper,the corresponding modules of fine particle removal technology and fluid dynamics software are understood,and the advantages and disadvantages of various agglomeration techniques and simulation methods are compared.On the basis of summarizing the previous researches on the agglomeration technology of fine particles,further studies on the techniques of vapor phase-change agglomeration and turbulent agglomeration.The UDF was used to write a kernel function suitable for the vapor phase-change agglomeration technique,and the technique was coupled with the turbulent agglomeration technique.First of all,a vapor phase change reunion chamber was established,and the effect of the amount of steam and flue gas temperature on the agglomeration of fine particles was analyzed.The results show that the supersaturated environment is a necessary condition for heterogeneous nucleation.The more steam is added,the better the fine particle size increases.The greater the temperature difference between flue gas and steam,the higher the degree of supersaturation,the more significant the effect of particle size growth.Secondly,the agglomeration of fine particles and the effect of pressure drop in the agglomeration chamber under the two types of "one" and "C".The results show that the "C"-shaped scroll can produce a symmetric vortex structure compared to the "one" shaped scroll,and the number of outlet large particles is more dense and the "C"-shaped scroll can have a smaller Pressure drop level.The optimal arrangement of the "C"-shaped scroll was optimized and the best vortex spacing was selected.Finally,a new type of phase-change aggregation chamber is proposed based on vapor phase transition and turbulent agglomeration.The characteristics of the flow field and the agglomeration effect of the new phase change reunion chamber were analyzed,and the agglomeration effect was analyzed.It was confirmed that the new agglomeration chamber had good agglomeration effect.更多还原