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<正>筛板塔是应用历史最久的塔型之一。至今人们仍在对筛板塔进行大量的研究,但对筛板塔处于不同鼓泡层的结构及筛板塔各操作状态之间的划分这一课题,还基本上限于一些定性的直观描述。筛板塔的各操作状态之间主要由两点速度划分,即漏液气速和喷射转变气速。在他们之间筛板处于泡沫工况,当气速高于喷射转变气速时,筛板塔处于喷射工况。这两种工况是人们最感兴趣的,这不仅因为在工业上这两种工况用得最多,而且还因为在流动泡沫工况下气体为分散相,液体为连续相,一旦转变为喷射工况就发生了相变,气体变为连续相,原来是连续相的液体则被气体吹散为小液滴的分散相。这种工况的转变必然强烈地影响着两相间的传质,要掌握塔板上两相间的传质规律,首先要确定它是处于何种工况。 相似文献
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前已对大孔筛板传质的液膜控制点效率进行了测定,本文将讨论板上流动工况、操作参数及塔板结构参数对液膜控制的传质单元数的影响及其数学模型。 一、板上流动工况对点效率的影响 在筛板塔的操作过程中,当气速由小增大时,一般经历下列四种工况:鼓泡工况、蜂窝状鼓泡、泡沫工况及喷射工况。通 相似文献
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旋流塔板有复杂的气液接触状态。对应于一定的气液接触现象,气液接触状态可分为倾泻区、泡花区、喷射区和全喷射区。在四种接触状态下,塔板有效压降与气速的关系有明显的差别。以有效压降随气速变化规律的转化点作为气液接触状态的转化点,确定了塔板上各种气液接触状态的区域,并关联了接触状态转化点的操作条件。对喷射区有效压降的分析得到,有效压降主要决定于塔板上液体产生的静压降,气体径向速度可以忽略,而使喷射区内有效压降不受气速影响。全喷射区内,气速影响溢流管和溢流锥的溢流能力,而使气速明显地影响塔板有效压降。泡花区内,漏液量随气速的增大而减小;因此,气速影响塔板有效压降。适当地简化流况,提出了有效压降关联式,利用实验数据确定了其中的参数。 相似文献
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新型垂直筛板是以气相为连续相,液相为分散相的高效喷射型塔板与通常在泡沫状态下操作的浮阀、筛板、泡罩塔板有根本性的区别,它具有高效率、大通量、低压降等优点,具有广泛的工业应用前景。 相似文献
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塔板上两相操作工况与雾沫夹带量的变化相关。在某气速下连续改变液流速率,雾沫夹带量呈马鞍形的变化,最低点所对应的清液深度,Zc约30—40mm,定义为“雾沫夹带转变点”。 当清液深度低于转变点,两相处于喷射或喷射主导工况;反之,两相处于泡沫或泡沫主导工况,雾沫夹带转变点即两种工况的过渡点。工况过渡不是突变而是渐变。文中对影响雾沫夹带变化的因素及工况过渡的特点进行了讨论。 作者提出,流行的雾沫夹带计算式——Hunt公式一般只适用于泡沫工况而不适用于喷射工况的操作过程。 相似文献
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一种具有机械消泡功能的新型塔板 总被引:3,自引:0,他引:3
研究开发了一种具有机械消泡功能的新型塔板。该塔板是在普通塔板上放置一种特制的新型机械消泡构件。该构件由相互平行的波纹消泡板组成,构件下半部分沉浸在塔板泡沫层中,起削弱泡沫层波峰高度和降低泡沫层高度的作用,上半部分处于泡沫层上部的气相空间,起惯性除沫的作用。实验结果表明:对于易起泡物系,机械消泡构件能降低雾沫夹带量61%~76%,并大幅削弱泡沫层表面过高的泡沫波峰;对不易起泡物系,机械消泡构件还能降低泡沫层高度15.2%~17.1%。因此,该塔板可以起到延缓塔板泡沫层过高液泛和过量雾沫夹带液泛的作用,具有良好的消泡效果。 相似文献
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Based on the results of the gas flow field, the droplet size distribution and the droplet initial flow rate distribution on a Φ300 mm rotating stream tray (RST), a three-dimensional droplet projection trajectory model, and a mass transfer model have been developed. The calculation of the models was carried out by a finite-difference procedure. The predicted results of the tray efficiency agree quite well with the experimental data measured with absorbing NH3 or SO2 in water on a Φ300 mm RST column and with the industrial data from a Φ3600 mm RST column. Meanwhile, the influence of absorbing system and the RST structure on the tray efficiency is discussed. 相似文献
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APPLICATIONANDFUNDAMENTALRESEARCHOFROTATINGSTREAMTRAYTanTianen;ShiHuixiang;ChenJianmeng;ShiXiaorong(DepartmentofChemicalEngin... 相似文献
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采用LSA-Ⅲ型激光粒度仪对一种常用的小流量空气雾化喷嘴的液滴雾化性能进行实验研究。实验主要测定了不同气液比、气相压力和液相压力情况下沿喷雾轴向不同位置处的液滴粒径分布。测定结果表明气液比和气相压力对雾化液滴粒径影响均较大,其中气相压力影响最大,气液比其次,液相压力影响最小。在本实验测定条件下,经过喷嘴雾化后在轴向100、200、300、400和500 mm位置处液滴的表面积平均直径(SMD)和体积平均直径(D43)出现波动性变化。通过对实验测得液滴粒径分布数据的分析,可以得到Rosin-Rammler分布函数中的特征参数和n,为定量计算液滴粒径提供理论基础。 相似文献
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A comprehensive three-dimensional model of droplet-gas flow was presented to study the evolution of spray in the effervescent atomization spray with an impinging plate.For gas phase,the N-S equation with the k-ε turbulence model was solved,considering two-way coupling interaction between droplets and gas phase.Dispersed droplet phase is modeled as Lagrangian entities,accounting for the physics of droplet generation from primary and secondary breakup,droplet collision and coalescence,droplet momentum and heat transfer.The mean size and statistical distribution of atomized droplets at various nozzle-to-plate distances were calculated.Some simulation results were compared well with experimental data.The results show that the existence of the impinging plate has a pronounced influence on the droplet mean size,size distribution and the droplet spatial distribution.The air-to-liquid ratio has obvious effects on the droplet size and distribution. 相似文献
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Size distribution of droplets above a rotating stream tray and model of droplet motion therein 总被引:1,自引:0,他引:1
Droplet size distributions have been investigated with a two-probe system above a rotatingstream tray of 300 mm diameter.The measured distributions are found to follow the upper limitedlognormal distribution with three parameters dependent primarily on gas hole F-factor.A probabilitymethod is used to describe the initial state of the droplet population above the tray,and a model fordroplet motion is presented.The results computed with model agree well with experimental data. 相似文献
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Sina Amini Dariush Mowla Mahdi Golkar Feridun Esmaeilzadeh 《Chemical Engineering Research and Design》2012
In this study, a mathematical model is developed to predict the efficiency of a down-hole oil–water separation hydrocyclone. In the proposed model, the separation efficiency is determined based on droplet trajectory of a single oil droplet through the continuous-phase. The droplet trajectory model is developed using a Lagrangian approach in which single droplets are traced in the continuous-phase. The droplet trajectory model uses the swirling flow of the continuous-phase to trace the oil droplets. By applying the droplet trajectory, a trial and error approach is used to determine the size of the oil droplet that reaches the reverse flow region, where they can be separated. The required input for the proposed model is hydrocyclone geometry, fluid properties, inlet droplet size distribution and operational conditions at the down hole. The model is capable of predicting the hydrocyclone hydrodynamic flow field, namely, the axial, tangential and radial velocity distributions of the continuous-phase. The model was then applied for some case studies from the field tested DOWS systems which exist in the literature. The results show that the proposed model can predict well the split ratio and separation efficiency of the hydrocyclone. Moreover, the results of the proposed model can be used as a preliminary evaluation for installing a down-hole oil–water separation hydrocyclone system in a producing well. 相似文献
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采用空气-水体系,对折板式汽液分离元件进行冷态模拟实验,研究了气速、液滴粒径、折板形式、间距及安装方式等参数对折板分离效率和压降的影响. 结果表明,气速控制在1~6 m/s,液滴粒径控制在50~80 mm,折板采用立式和卧式安装,形式采用V形和W形,间距为10~50 mm,对分离性能均有一定的影响,折板间距为20 mm的分离元件具有较高的分离效率. 通过对冷态实验数据进行数学回归分析,获得描述折板性能的经验公式,与实验值误差在10%内,同时在海水淡化中试试验装置中验证了折板式汽液分离元件的分离性能. 相似文献
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用实验和模拟的方法研究了直径为3.2 mm的单个蒸馏水液滴与冷板面(温度低于273 K)撞击铺展和固化过程,分析了撞击高度(100、250、500 mm)、板面温度(253、268 K)、板面倾角(0°、30°和60°)对撞击过程的影响以及液滴在冷板面上冻结过程。并模拟了单个普鲁兰多糖溶液液滴在撞击高度为100 mm、板面温度为253 K的过程。结果表明,撞击高度与板面温度对液滴在水平冷板面的铺展过程起到重要作用,板面倾角会影响液滴撞击倾斜板面时的冷冻沉积。物料的黏度会影响液滴冷冻沉积时的铺展速率及铺展直径,而对于较高黏度物料,温度并不起决定作用。模拟和实验结果吻合较好,反映了液滴铺展冻结过程中的温度变化,有利于直观解释液滴发生冻结的状况。 相似文献