排气管偏置分离器分离性能的数值模拟

采用雷诺应力模型（Reynolds stress model,RSM）对旋风分离器排气管中置和偏置时的气相流场进行了数值模拟,并用拉格朗日法模拟了分离器内颗粒的运动轨迹。气相流场模拟结果与实验结果吻合得较好。结果表明：排气管偏置后,分离器内沿排气管偏置方向的切向速度有所提高,排气管下部短路流较小,颗粒离心运动更加强烈,提高了分离效率的同时压降变化不大,分离器经济性更好。     

一种新型气固分离器内两相流动的数值模拟

采用数值模拟的方法对带有切向开缝中心管式气固分离器的气固两相流进行了研究.计算中对气相采用了雷诺应力模型,对颗粒相采用了Lagrange坐标系下的随机轨道模型.结果表明:气相流场总体特征为拱形空间内气流以切向速度为主绕排气管做旋转运动,切向气速随径向位置的增加而减小.大部分气体通过开缝进入中心排气管而从中心管排出,少部分气体由排气管下方空间返回入口区.颗粒相的引入对气相流场有显著的影响,分离器拱形空间内同一径向位置的气体切向速度明显降低.颗粒由于自身惯性向边壁运动的趋势改变了气相流场分布,使气体更易向中心管内运动,从而达到较高的分离效率.计算得到的分离效率与实测值吻合较好,证明了数学模型的合理性,为进一步优化分离器结构提供了可靠依据.     

直流导叶式旋风管性能的数值模拟研究

应用fluent6.3软件,RNG k-ε模型,对直流导叶式旋风管流场进行数值模拟,分析了装置的压降特性;应用欧拉-拉格朗日2相流思想,通过离散颗粒模型（DPM）模型,对装置在不同颗粒粒径下的分离效率进行了模拟.结果表明,直流导叶式旋风管压降和分离效率的影响因素主要包括气流进口流速和装置结构参数2方面.随着进口流速的增大,装置压降增大,分离效果显著提高;对于装置结构,则分剐研究了进口包括导流叶片偏转角及个数,分离段长度和排气管入口结构包括内径、插入深度及形状,得到部分结论为：增大导叶偏转角或增大分离段长度,压降增大,分离效果提高;增大排气管入口内径,压降减少,分离效果减弱;随着直筒、锥形、直筒＋锥形改变,压降逐渐减小.数值模拟结果与实验结果有较好的一致性,因此,数值模拟对于设计过程中压降和分离效果的预测起到了较好作用.     

一种新型气固分离装置结构的优化研究

在已有实验的基础上,结合大型冷模实验、流场实验和计算流体力学(CFD)模拟的结果,以压降和分离效率为综合评价指标,对后置烧焦管出口的气固分离器中心排气管位置(偏心)和中心排气管开缝形式进行了考察。结果表明,保持其它尺寸与基准型分离器一致而中心排气管改为切向开缝形式的分离器,既能保持分离效率不低于基准型分离器,又能降低压降,在实验条件下压降不超过1 900 Pa,分离效率大于98%     

环流预汽提组合旋流快分系统粒级效率的三区计算模型

在大型提升管冷模实验装置上,系统地考查了带有环流预汽提的旋流快分(CVQS)系统的气相流场和粒级效率。结果表明,随着旋流快分系统喷出口气速的增加,粒径小于7μm颗粒的粒级效率的变化较小,7~20μm颗粒的粒级效率逐渐变小,而超过20μm颗粒的粒级效率则逐渐增大。根据CVQS快分系统的气固分离原理和结构特点,建立了计算CVQS系统粒级效率的三区模型。计算结果表明,在颗粒粒径大于20μm时,模型预测的粒级效率与实验值吻合较好,其最大相对偏差不超过6.1%;在颗粒粒径小于20μm时,模型计算的粒级效率与实验值相差较大,其相对偏差在45.7%~80.3%之间变化,并且随着颗粒粒径的减小,其相对偏差逐渐增加。模型对于主要用于分离20μm以上颗粒的CVQS系统的工程设计,具有重要参考价值。     

催化裂化沉降器新型高效旋流快分器内气固两相流动

用CFX软件对催化裂化沉降器新型旋流快分器的气相流场进行了三维模拟,湍流模型采用雷诺应力输运方程模型.计算结果与用五孔探针测试的气相流场实验结果吻合很好.采用离散轨道模型对该旋流快分器内颗粒的运动情况进行了计算,并由此估算了旋流快分器的分级效率和总分离效率.模拟结果表明：该新型旋流头可消除现有旋流头喷出口附近的短路流,更有利于提高旋流快分器的效率.两种结构形式的旋流快分器分离效率的计算对比说明：在旋流头处加入一个内构件,是很有价值的改进.     

环流预汽提组合旋流快分系统粒级效率的三区计算模型

在大型提升管冷模实验装置上,系统地考查了带有环流预汽提的旋流快分(CVQS)系统的气相流场和粒级效率。结果表明,随着旋流快分系统喷出口气速的增加,粒径小于7 μm颗粒的粒级效率的变化较小,7～20 μm颗粒的粒级效率逐渐变小,而超过20 μm颗粒的粒级效率则逐渐增大。根据CVQS快分系统的气固分离原理和结构特点,建立了计算CVQS系统粒级效率的三区模型。计算结果表明,在颗粒粒径大于20 μm时,模型预测的粒级效率与实验值吻合较好,其最大相对偏差不超过6.1%;在颗粒粒径小于20 μm时,模型计算的粒级效率与实验值相差较大,其相对偏差在45.7%～80.3%之间变化,并且随着颗粒粒径的减小,其相对偏差逐渐增加。模型对于主要用于分离20 μm以上颗粒的CVQS系统的工程设计,具有重要参考价值。     

动态旋风分离装置分离效率的理论与实验研究

对普通旋风分离器进行改进,设计了一种带有旋转叶片的逆流式动态旋风分离装置,并对其分离效率进行了实验和理论计算。结合Alexander准自由涡模型、Barth平衡轨道模型及Chmielniak和Bryczkowski对顺流动态旋风分离器的研究,获得了装置的理论分离效率的计算方法,并与实验中通过静电低压旋风颗粒取样器(ELPI)获得的分离效率进行了对比及修正。修正后的理论解与实验获得的分离效率偏差在5%以内,理论方法对装置的分离效率能够进行准确的预测,同时实验数据表明,该种设备分离效率随入口气速和旋转叶片转速的提高而增强,且该装置对于5μm以上的颗粒具有较好的分离效果。     

切流式三旋单管内固相颗粒运动规律的数值研究

采用商用软件Fluent 6.3,利用随机轨道模型对切流式三旋单管内固相颗粒运动轨迹进行了数值模拟,结果表明颗粒运动轨迹随机性较大,对气流的跟随性较好,受湍流脉动的影响较大。颗粒在单管内的逃逸与捕集运动规律的统计结果表明:不大于5μm的颗粒主要在排气管底部和分离筒体发生逃逸,随着粒径的增加,颗粒的分离效率增加,在排气管底部和分离筒体上部逃逸比重增加,而在分离筒体中底部颗粒的逃逸比重减少。总结来说,排气管短路流、分离筒体内旋流夹带逃逸是影响切流式三旋分离性能的主要原因,可以从这些方面进行三旋分离性能的优化与改进。     

FCC内置式四旋分离系统内气固两相流场的数值研究

通过数值模拟的方法,采用RSM湍流模型对FCC内置式四旋分离系统内气固两相流场进行了研究.研究表明,四旋灰斗底部存在错流,不利于排料;储料罐顶部平衡管泄气有利于四旋排料,但同时增加了颗粒逃逸的概率,降低分离系统效率;分离系统内颗粒运动轨迹包括灰斗捕集、排气管逃逸及平衡管逃逸,控制颗粒在平衡管逃逸可通过在储料罐内添加锥形挡板结构实现;四旋环形空间顶部与灰斗底部锥段颗粒浓度较高,易对四旋内壁产生磨损;内置式四旋分离系统优点在于不存在催化剂跑损问题.     

Gas-solids separation model of a novel FCC riser terminator device: super short quick separator (SSQS)

The gas flow field and the separation efficiency of a novel fluid catalytic cracking (FCC) riser terminal device, named as Super Short Quick Separator (SSQS), were studied. On the basis of above investigations, a section-lateral-mixing separation model was proposed, which included both the effect of inertia and structure of gas outlet on particles capture. After final modification, the results predicted with this model could be in good agreement with the cold experimental data. According to this model, the separation efficiency of SSQS is mainly influenced by the difference between the arc radius and the center pipe radius as well as the magnitude of particle tangential velocity.     

Gas-solids separation model of a novel FCC riser terminator device: Super Short Quick Separator (SSQS)

The gas flow field and the separation efficiency of a novel fluid catalytic cracking (FCC) riser terminal device, named as Super Short Quick Separator (SSQS), were studied. On the basis of above investigations, a section-lateral-mixing separation model was proposed, which included both the effect of inertia and structure of gas outlet on particles capture. After final modification, the results predicted with this model could be in good agreement with the cold experimental data. According to this model, the separation efficiency of SSQS is mainly influenced by the difference between the arc radius and the center pipe radius as well as the magnitude of particle tangential velocity. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 22(1): 65–70 [译自: 高校化学工程学报]     

Mechanism of micro-particle motion across falling liquid cylinder for PM2.5 separation (Ⅰ)Trajectory of particle motion towards surface and separation radius

提出了横掠液柱流的速度场和温度场推动PM_2.5微粒附面运动机理,建立了微粒附面运动微分方程和数值积分反演方法,计算粒子运动轨迹并预测可吸收的微粒运动最大分离半径。定义最大分离半径与液柱表面之间附面层的厚度为分离厚度,以气溶胶流体通过该区域的体积流量与横掠单液柱的总体积流量之比代表单液柱吸收效率;热泳推动力是强化吸收效率的主要因素。基于单液柱吸收效率,按串联模型导出规则排列的液柱群整体分离效率计算公式,依据液柱交叉流几何结构、流体流动和气液两相传热传质参数即可确定整体分离效率。对交叉流Reynolds数为170的实例计算显示,直径4 mm的单液柱吸收效率为1.18%,由195排液柱群组成的长度为1170 mm的分离通道整体分离效率达到90%。     

横掠液柱流的微粒运动机理及PM2.5捕获(Ⅰ)附面运动轨迹与分离半径

提出了横掠液柱流的速度场和温度场推动PM_2.5微粒附面运动机理,建立了微粒附面运动微分方程和数值积分反演方法,计算粒子运动轨迹并预测可吸收的微粒运动最大分离半径。定义最大分离半径与液柱表面之间附面层的厚度为分离厚度,以气溶胶流体通过该区域的体积流量与横掠单液柱的总体积流量之比代表单液柱吸收效率;热泳推动力是强化吸收效率的主要因素。基于单液柱吸收效率,按串联模型导出规则排列的液柱群整体分离效率计算公式,依据液柱交叉流几何结构、流体流动和气液两相传热传质参数即可确定整体分离效率。对交叉流Reynolds数为170的实例计算显示,直径4 mm的单液柱吸收效率为1.18%,由195排液柱群组成的长度为1170 mm的分离通道整体分离效率达到90%。     

A new liquefaction method for natural gas by utilizing cold energy and separating power of swirl nozzle

A swirl nozzle with a central body was newly designed to make full use of the cold energy and separating power, and the coupling of swirling flow and condensation was realized based on a condensation model, a droplet surface tension model and a Reynolds stress model turbulence model. The flow and condensation characteristics of methane gas under supersonic swirling flow conditions were studied. The results show that the flow and condensation parameter distribution in the swirl nozzle are similar under varying swirling intensities, but the swirling performance improves with the increase in swirling intensity, and a tangential velocity is beneficial before the gas enters the nozzle. As the inlet temperature decreases or the inlet pressure increases, the liquefaction efficiency increases, and the gas condensation process can be promoted. With the advancement of the initial nucleation position and the increase in the droplet radius, the separation efficiency of the swirl nozzle increases.     

注气对油水分离水力旋流器流场影响模拟分析

采用雷诺应力湍流模型、混合模型和离散相模型对注气型油水分离水力旋流器进行数值模拟,得到其内部流场的速度分布和油滴粒子运动轨迹,分析对比了注气前后进口流量、分流比和充气量对分离效率的影响,数值计算结果与文献实验值进行了比较。结果表明,充气后流场速度增加,油滴粒子逃逸时间缩短,旋流器分离效率提高5%~10%,在一定条件下气浮对旋流分离起到强化作用。     

基于离心与惯性作用的新型气固分离装置的结构

后置烧焦管出口的气固分离装置是实现后置烧焦管式组合再生工艺的关键设备之一. 在对气固分离机理系统分析的基础上,开发了一种基于离心与惯性协同作用机理的新型气固分离装置. 以滑石粉为物料,在相同实验条件下对9种不同结构尺寸的分离器的分离效率和压降进行了实验测定. 结果表明,不加挡板、不加折边、开缝宽度相同、无因次排气管径在0.50~0.55范围内的结构比较合理.     

Investigation on Separation Efficiency in Supersonic Separator with Gas-Droplet Flow Based on DPM Approach

Supersonic separator is a new technology based on the adiabatic expansion of swirling gas flow, and at present it has demonstrated great application potential in separating and processing droplet liquid contained in natural gas. However, its coefficient of performance is still low and there seems to be a large gap in the method that evaluates the separation efficiency in a satisfactory manner. In order to promote the wide application of this technology in the dehydration field, it is necessary to find a new and feasible approach that can be used to predict the flow characteristic and separation performance inside a supersonic separator. In this paper, a comprehensive three-dimensional fluid numerical model to study the flow behavior and separation efficiency in a supersonic separator was established coupled with the discrete particle model (DPM). The mixture of air and water droplets was chosen as working fluid. The gas phase was modeled with compressible Navier–Stokes equations for two-phase flow and the RSM turbulence model was taken into account. The droplet phase was modeled with the discrete particle model (DPM), in which the droplets are assumed to have the same sphere shape and ignore the phase transition and nucleation process. A pilot test facility was carried out to validate the numerical model. The experimental results not only indicate that the new dehydration device can efficiently separate the liquid droplets from wet gas, but also prove that the numerical results were great agreements with the experimental results. Furthermore, based on the proposed numerical approach, the gas-droplet turbulent flow structures were predicted, the effects of different structure parameters and operation conditions on the separation efficiency were also investigated. The current works settle a foundation for further explorations on the supersonic gas–liquid separation flows inside a supersonic separator as well as the possible new applications.     

CFD技术在油气分离器选型和设计中的应用

利用CFD数值模拟方法,气相采用RNGκ-ε湍流模型,油滴相采用随机轨道模型,对油气两相流在一次油份内的流动分布进行研究,分析油滴在分离器内的运动轨迹及分离机理。计算结果表明:油气分离器的长径比越大其分离效果越好;当入口速度较大时,增大分离器容积可提高分离效率;当入口速度较慢时,即使增大容积其分离效果也不会得到明显的改善;分离器入口速度越大分离效果越理想。在工程应用中,利用以上分析结论进行选型和尺寸设计的油气分离器可以满足实际要求,并取得理想的分离效果,同时验证了采用的方法切实可行。     

Improving the efficiency of gas hydrate crystallization due to the application of gas separation membranes

To improve the efficiency in of the separation and purification of gases by the method of gashydrate crystallization, the possibility of combining it with the membrane method has been studied. A mathematical model has been proposed for the hybrid-membrane gas-hydrate method. The application of membrane methods in gas-hydrate crystallization has been shown to prevent admixtures from concentration in a crystallizer and, thus, to considerably improve the efficiency of the gas separation and purification process. The proposed model of gas separation and purification was used to calculate the ratio of freon-12 purification from nitrogen and oxygen. The application of membrane gas separation with the purpose to prevent an admixture from concentration in a crystallizer was shown to increase the efficiency of freon-12 purification from nitrogen and oxygen via gas-hydrate crystallization by more than an order of magnitude at a high product takeoff (no less than 0.6).