组合约束型提升管出口段下行颗粒流动特性

发布时间：2018-01-04 23:34

本文关键词：组合约束型提升管出口段下行颗粒流动特性　出处：《河北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在石油炼制领域,“提升管+气固分布器+流化床层”形式反应器得到了较多的研究和应用,“气固分布器+流化床层”形式的出口结构是组合约束型提升管的主要构型特征,而提升管出口段下行颗粒及团聚物的出现不仅是“气固分布器+流化床层”式出口约束的一种直观体现,其自身的流动特性也是影响出口段气固总体流动特性的重要因素。因此,本文选取距出口较近的提升管中上部(统称为“出口段”)为研究区域,以下行颗粒为研究对象,通过对下行颗粒流动参数的测量,及与常规提升管内下行颗粒流动参数进行对比,综合分析组合约束型提升管出口段下行颗粒流动特性,以期为深入揭示“气固分布器+流化床层”的出口约束影响机制提供参考。结果表明,组合约束型提升管出口段沿轴向向下可以分为三个流动区域:①Ⅰ区——出口约束与变径结构协同影响区,②Ⅱ区——出口约束与气体提升协同影响区,③Ⅲ区——气体提升影响区;下行颗粒团聚物与下行颗粒整体的动力学性质是相关的;下行颗粒局部固含率、速度、返混比和下行颗粒团聚物局部固含率、速度、持续时间、尺寸沿径向上由中心到边壁均呈逐渐增大的分布趋势,径向各位置都随表观气速及分布器开孔率的增加而降低,随颗粒循环强度及上部流化床层压降的增加而增加,沿提升管出口轴向向下,均呈先增加再降低,然后再增加的发展趋势,而下行颗粒团聚物频率在径向上的分布趋势以及随条件的变化情况与之相反;下行颗粒团聚物特性参数与其流动参数存在对应关系:随着下行颗粒团聚物尺寸增大,其聚集与解体频率呈减小趋势,下行速度与固含率均呈增大趋势;随着团聚物聚集与解体频率增加,其固含率和速度均呈减小趋势;随着团聚物固含率增加,其下行速度呈增大趋势;综合提升管内表观气速、系统颗粒循环强度、上部流化床层压降、气固分布器开孔率影响,对出口约束与气体提升协同影响区内不同轴径向位置下行颗粒团聚物尺寸进行了关联,其平均相对误差为7.5%。
[Abstract]:In the field of oil refining, "riser + gas solids distributor + fluidized bed reactor form has been researched and applied more," the export structure of gas solid fluidized bed + distributor "form is a combination of constraint to improve the main configuration features of the tube, and improve the exit and downward particle agglomerates only is the gas solid fluidized bed + distributor" export constraints a visual manifestation, an important factor in its flow characteristics also affect the export of gas and solid overall flow characteristics. Therefore, this paper selects from near an exit in the upper part of the riser (collectively referred to as the "exit section") as the study area, the following line particles as the research object, through measuring the downward particle flow parameters, flow parameters and conventional riser descending particles were compared, the flow characteristics of pipe outlet section downstream particle comprehensive analysis with combined restraint in order to improve. To reveal the "export restraint mechanism of the effect of gas solid fluidized bed + distributor" to provide the reference. The results show that the combination of constraint type riser outlet section along the axial direction can be divided into three areas: 1 - flow constraints and variable structure coordinated export affected zone, the zone II - export restriction and the synergistic effect of gas lift the District, District III - gas lift affected zone; particle agglomeration dynamics and downlink downlink particles is related to the overall downward particle; local solid holdup, speed, mixing ratio and downstream aggregates local solid holdup, speed, duration, size along the radial direction from the center to the edge on the wall the distribution is gradually increased, the radial position with the increase of apparent gas velocity and distributor opening rate decreased, increased with the increase of pressure drop of particles and the upper part of the bed circulation intensity, along the riser outlet axial downward, Were all increased first and then decreased, and then increased trend, distribution and trend of downward aggregates in the radial direction and frequency with the conditions on the contrary; down aggregates characteristic parameters and flow parameters are corresponding with the downstream particle group polymer size increased, the aggregation and disintegration of the frequency is the decreasing trend, downward speed and solid holdup increased; with the agglomerate aggregation and disintegration of the increased frequency of solid holdup and velocity decreased; with the agglomerate solid holdup increases, the downstream speed showed increasing trend; comprehensive riser superficial gas velocity, particle circulation system strength. The upper part of the bed pressure drop of gas solids distributor opening rate impact on export restriction and the synergistic effect of gas lift in different axial and radial positions downstream aggregates size were correlated, the average relative error is 7.5%.

【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE96

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