Effect of inlet area on the performance of a two-stage cyclone separator

The cyclone separator is an important separation device.This paper presents a new type of embedded two-stage cyclone,which includes a 2 nd-stage cyclone(internal traditional cyclone)with multiple inlets and a 1 st-stage cyclone(outer cylinder)that unifies the 2 nd-stage cyclone inlets into one inlet.The Taguchi experimental method was used to study the two-stage cyclone separator’s inlet area on its performance.Studies have shown that the increase of the 1 st-stage cyclone inlet area and the increase in the number of 2 nd-stage cyclone inlets(N)positively affect reducing the pressure drop and a negative effect on efficiency.It is recommended to use 2 S(the original 1 st-stage cyclone inlet area)of the 1 st-stage cyclone inlet area and 2 N of the 2 nd-stage cyclone inlets when separating fine particles.Compared with a traditional cyclone,the pressure drop is reduced by 1303 Pa,the mass separation efficiency(Eq)is increased by 0.56%,and the number separation efficiency(En)is increased by 2.05%.When separating larger particles,it is recommended to use 2 S of the 1 st-stage cyclone inlet area and 4 N of the 2 nd-stage cyclone inlets.Compared with a traditional cyclone,although Endecreases slightly,the pressure drop is reduced by 3055 Pa,and the Eqis increased by 0.56%.The research results provide new insight into the design of the cyclone.

Cyclone dimensionless pressure drop,cut size,and separation slope:One dimensionless number(Reynolds)to rule them all

The flow field and performance characteristics of the high-efficiency Stairmand cyclone have been computationally investigated at a wide range of Reynolds numbers Reout=84−252876 by varying the cyclone diameter,inlet velocity,operating temperature and pressure using the LES simulations.The effects of these parameters on the dimensionless cyclone performance characteristics(Euler number,square root of Stokes number and slope of the transformed grade efficiency curve)and dimensionless lip flow and lip velocity have been revealed.Five critical Reynolds numbers which correspond to the transition between different regimes and sub-regimes have been determined.All three dimensionless cyclone performance characteristics and two lip flow characteristics are ruled by the Reynolds number.

Pressure Drop in Cyclone Separator at High Pressure

For the design of pressurized circulating fluidized beds, experiments were conducted in a small cyclone with 120 mm in diameter and 300 mm in height at high pressures and at atmospheric temperatures. Influence of air leakage from the stand pipe into the cyclone was specially focused. A semi-empirical model was developed for the prediction of the pressure drop of the cyclone separator at different operate pressures with the effect of air leakage and inlet solid loading. The operate pressure, air leakage and inlet solid loading act as significant roles in cyclone pressure drop. The pressure drop increases with the increasing of pressure and decreases with the increasing of the flow rate of air leakage from the standpipe and with the increasing of the inlet solid loading.

Research on High-Efficiency Cyclone Separators and Their Optimum Design

ＲｅｓｅａｒｃｈｏｎＨｉｇｈＥｆｉｃｉｅｎｃｙＣｙｃｌｏｎｅＳｅｐａｒａｔｏｒｓａｎｄＴｈｅｉｒＯｐｔｉｍｕｍＤｅｓｉｇｎＳｈｉＭｉｎｇｘｉａｎ，ＪｉｎＹｏｕｈａｉ，ＷｕＸｉａｏｌｉｎ，ＣｈｅｎＪｉａｎｙｉ，ＬｉｕＪｕｎｒｅｎ（ＵｎｉｔｅｄＲｅｓｅ...

Control of Collection Efficiency for Axial Flow Cyclone Dust Collectors with Fixed Guide Vanes and with Funnel Shaped Exit Pipes

The experimental result of the collection efficiency of the axial flow cyclone with the fixed guide vanes is lower than that with the tangential inlet pipe to the cyclone body due to the weak angular momentum transfer given by flowing through the guide vanes. However, one of the interesting points is the control of the collection efficiency depended on the funnel shaped exit pipes. The collection efficiencies for these funnel shaped exit pipes are depended on the Froude number. Then, in this paper, the experimental results of the pressure drop and also the collection efficiency using the fly-ash particles and also the comparison of the calculated results of the collection efficiency with the experimental results are described i~ detail.

Collection Efficiency of Cylindrical and Elliptic Cyclone Dust Collectors with Vortex Breaker

The cyclone dust collector is applied to many kinds of industries and also there are many types of cyclones which are selected for the application and the placement of the establishment. However the cross section of these cyclones is the circular cylindrical section for the optimum condition of the turbulent rotational flow. However from the energy consumption and the collection efficiency points of view, the circular cross section of the cyclone is not always recommended but the elliptic cross section is recommended. Therefore in this paper, the detailed experimental results of the collection efficiency for the circular cross section and for the elliptic cross sections of the eccentricity =0.5,0.6and 0.7 are reported. The test dust for these experiments is fly-ash of the mean diameter Xpm=18.0 μm and 18.3 μm. The feed particle concentration is Co=1.0-50 g/m3.

Structural Optimization of a Novel Up-run Gas-solid Separator

A new gas-solid separator dedicated to heavy-oil fast pyrolysis process incorporating inertial and centrifugal separation was designed. Gas and typical fluid catalytic cracking （FCC） catalyst particles （with a density of 1500 kg/m3, and a mean diameter of 45.81 p.m） were used in the study. The inlet gas velocity was kept constant at 13.36 m/s, while the solid loading at the inlet ranged from 0 to 700 g/m3. When the exhaust pipe opening was provided with two narrow-width slots near the inlet without baffles, the solid collection efficiency increased with an increasing solid loading at the inlet and was close to 95% along with a decreasing pressure drop. After increasing the secondary separation structure, the separation efficiency greatly improved. By adjusting the diameter of the secondary exhaust pipe, the separation efficiency and pressure drop could be balanced. Under the experimental conditions, when the diameter of the second exhaust pipe was equal to d=100 mm, the pressure drop was lower than 1400 Pa while the separation efficiency could exceed 99.50%; and when the diameter was equal to d=120 mm, the pressure drop was less than 700 Pa, with the separation efficiency reaching over 99.00%.

Numerical Simulation and Experimental Study on the Performance of Gas/liquid Spiral Separator

The gas/liquid spiral separator, a key component in the compressed air system, was used to remove liquid and oil from gas stream by centrifugal and gravitational forces. To optimize the design of the separator,the relationship between the performance and structural parameters of separators is studied. Computational fluid dynamics (CFD) method is employed to simulate the flow fields and calculate the pressure drop and separation efficiency of air-liquid spiral separators with different structural parameters. The RSM (Reynolds stress model)turbulence model is used to analyze the highly swirling flow fields while the stochastic trajectory model is used to simulate the traces of liquid droplets in the flow field. A simplified calculation formula of pressure drop in spiral structures is obtained by modifying Darcy's equation and verified by experiment.

Characterization of multiphase gas–solid flow and accuracy of turbulence models for lower stage cyclones used in suspension preheaters

This study involved the analysis and characterization of the multiphase flow phenomenon inside the lower stage cyclone separator used in the clinker burning process.The analysis was performed using both CFD and experimental research methods.Very few studies are devoted to such types of cyclone separators,which in addition to their basic functions are also responsible for the technological process.Due to the atypical working conditions of these cyclone separators,they are characterized with a complex geometry,which significantly differs from that of the traditional separators.Furthermore,the evaluation of the accuracy and level of reliability of the two models of turbulence closure—k-e RNG and RSM(RANS),and the LES.The results obtained led to the conclusion that for the lower stage cyclone separators,the LES model proved to be the most accurate(both in the case of forecasting the separation efficiency and pressure drop).The performance parameter(in particular the separation efficiency)values obtained for the RSM model were also characterized by high accuracy.The k-e RNG model was characterized by significantly larger deviations.

水力分级旋流器工艺参数匹配优化研究

针对选煤厂煤泥水处理中的水力分级旋流器存在工艺参数匹配不合理所导致设备分离性能偏低的问题。本文以选煤厂常用的YD350-14水力分级旋流器为研究对象,以分离效率和压力降作为旋流器分离性能的评价指标,基于响应面法与快速非支配排序遗传算法(NSGA-Ⅱ)模型开展对旋流器工艺参数(入料浓度、入料流量、安装角度)间的匹配关系研究。最终根据Perato前沿确定旋流器最佳工艺参数如下:在旋流器入料浓度12 g/L,安装角度80°,入料流量80 m^(3)/h时,可达到分离效率86.07%,压力降1155.62 Pa。对分离效率匹配模型进行现场验证,得出经过匹配后分离效率提高了5.07%,验证了该匹配模型能够有效提高旋流器的分离效率。本文研究为选煤厂中旋流器工艺参数的合理匹配提供理论依据,并为提高旋流器的分离效率开拓一个新的方向。

环栅式动力除尘器分离性能的数值模拟与实验

【目的】为提高环栅式动力除尘器的分离性能,研究结构参数与工况参数对分离效率和压降的影响,确定最优结构参数和工况参数。【方法】采用数值模拟方法研究结构参数对环栅式动力除尘器分离性能的影响,优化除尘器的结构参数,然后依据优化的结构参数设计除尘器,并搭建分离性能测试实验平台,研究不同工况参数对除尘器的分离效率和压降的影响,确定除尘器的最佳工况参数。【结果】净气流以较高气速通过除尘器后部环缝,颗粒的逃逸发生在最后2级环缝处,最后1级环缝处最高气速为57.88 m/s,一般逃逸颗粒的粒径≤22μm。环栅式动力除尘器优化结构尺寸为:筒体直径为150 mm,环厚度为20 mm,环栅数量为20,前16个环间距为8 mm,后4个环间距为2 mm,环高为5 mm,环错位为1 mm。环栅式动力除尘器优化工况参数为:抽气流量分数为20%,气速为15 m/s。【结论】在最优结构参数和工况参数条件下,环栅式动力除尘器分离效率最高,模拟值更接近实验值。颗粒质量浓度的变化对分离效率影响不大,环栅式动力除尘器适用于分离不同质量浓度的粉尘颗粒。

新型双筒体旋风分离器的分离性能和流场

为降低普通逆流式旋风分离器的阻力,设计了一种双筒体旋风分离器(简称双筒体分离器),即在筒体内部增加一个同心内筒、进口移至筒体下端、升气管插入内筒一段长度。通过冷模对比实验和数值模拟研究了该双筒体分离器的分离性能和流场。结果表明:双筒体分离器的效率在低入口气速区低于PV型高效旋风分离器(简称PV型分离器),但当入口气速高于28 m/s时则高于PV型分离器;双筒体分离器的效率总是高于环流式除尘器;压降与环流式除尘器相近但比PV型分离器低约50%。双筒体分离器耦合了常规逆流和直流旋风分离器中的2种旋涡流动,克服了逆流式分离器气体流路长和顶灰环的缺陷,同时还增加了部分细颗粒循环再分离的机会,效率高于直流式旋风分离器,是一种具有较低阻力和较高分离效率的新型旋风分离器,对于入口颗粒稍粗的分离应用具有显著的节能优势。

大型工业化费托合成装置气液分离元件的CFD模拟

为提高费托合成装置关键组分重质烃的气液分离效率,建立了波纹板上气液两相流的三维CFD模型,研究了复杂结构波纹板内流体流动特性,分析了分离器内气相速度场、压力场分布以及雾滴的运动行为,考察了分离器结构参数对压降和分离效率的影响规律,并对两种不同结构的波纹板进行了工业化运行验证。模拟结果表明:带钩波纹板对改善费托合成气相回路气液分离的效果作用明显,分离效率及压降随钩片长度和钩片倾角的增大而增大,随叶片间距的增大而降低;工业化运行验证结果表明:带有钩片的分离元件不适用于费托合成浆态床工艺,与带钩波纹板相比,应用光滑波纹板后,重质烃分离量提高,分离器阻力降降低,循环气量增加,反应转化率增长,重质烃分离性能提高,产物馏程分割更为精细。

针对矿山细粉尘的新型微雾旋风除尘系统

设计、研发一个高效、经济的新型微雾旋风除尘系统,以解决煤矿细颗粒粉尘难以捕集这一难题。采用离散相模型的粒子跟踪技术,对雾滴场与粉尘场进行耦合研究。并从粉尘质量浓度、分离效率和压降等指标对微雾旋风除尘系统和旋风分离器进行对比分析。结果表明:微雾旋风除尘系统的雾化场能够完全捕捉旋风分离器排气口逃逸的细颗粒粉尘,分离效率显著提高;同时,被捕捉沉降至灰斗的粉尘颗粒表面形成一层水膜,使细颗粒粉尘平均粒径增大,避免被气流再次卷起带走,可有效抑制二次扬尘。

天然气净化用多管旋风分离器的分离性能

为了系统评价天然气净化用多管旋风分离器的分离性能,在线测量了入口气速6～24m/s、入口颗粒浓度30～2000mg/m3范围内多管旋风分离器的分离效率和分级效率.结果表明,多管旋风分离器的分离效率和分级效率都随入口气速和入口颗粒浓度增大而提高.与单管旋风分离器相比,在相同实验条件下,多管旋风分离器的分离效率下降2%～15%;单管旋风分离器基本能除净粒径大于10μm的颗粒,而多管旋风分离器只能去除15μm以上的颗粒.多管旋风分离器的压降主要是内部单管旋风分离器的压降,占整个压降的80%～90%.

气液旋流分离器排气管结构试验

通过对气液旋流分离器分离性能的试验研究发现,排气管的结构尺寸对旋流器分离的临界速度及分离效率有显著影响。相对于传统的直管型排气结构,采用扩散锥形的排气管结构可以有效地削弱旋流分离器内短路流的影响,增大排气心管内液膜的形成速度,从而在保证压力降基本不变的前提下提高分离效率。旋流器分离的临界速度受物料含液浓度的影响不大,主要受排气管结构尺寸的影响。

缝隙式排气管对旋风分离器的性能影响

为降低传统旋风分离器工作时排气管内气流高速旋转造成的大量能量损失,将Lapple型旋风分离器的排气管改进为缝隙式排气管,利用数值模拟和实验的方法分析了缝隙式排气管对旋风分离器的性能影响.采用RSM模型对气相流场的切向速度、静压、流动轨迹、湍流强度以及压降进行数值模拟,采用多相流模型中的DPM模型对分离器的分离效率和颗粒运动轨迹进行仿真分析.仿真分析结果与实验验证结果吻合度较好,有较高的预报精度.最终结果表明,缝隙式排气管可使传统旋风分离器的压降下降6.8%,分离效率提升5.5%;当排气管上缝隙长度或宽度增加至一定数值,分离器的分离效率达到最大.随着排气管上缝隙长度或宽度的增加,旋风分离器的分离效率逐渐趋于稳定,压降持续降低;排气管上的矩形缝隙可使排气管内产生旋进涡核(PVC)现象,随着缝隙长度的增加,旋进涡核现象有所减弱,缝隙宽度的变化对旋进涡核现象影响较小;缝隙式排气管可有效抑制普通排气管中心处回流区的产生,并使普通排气管底部以及外旋流的湍流强度降低,从而减少排气管底部的短路流,提高分离效率.通过观察不同颗粒粒径的电石渣颗粒的运动轨迹,可知Lapple型旋风分离器与新型旋风分离器内部流场呈现出有利于固体颗粒分离的组合涡结构,排气管结构的改变并未影响分离腔的原始涡流结构.

PDC型高效旋风管的流场分析及结构改进

在ＰＤＣ型旋风管流场测试研究的基础上，开发了ＰＳＣ型旋风管，对比研究和分析结果表明，ＰＳＣ型旋风管结构简单，对细粉有较高的分离效率，使用性能指标优于ＰＤＣ型旋风管。

旋流板式气液分离器的放大规律

对旋流板式气液分离器在3种规模、18种旋流板结构下进行了模型实验研究,考察了旋流板结构参数(径向角、仰角和叶片数量)对分离效率和压降的影响,并建立了预测分离器压降的关联式,为旋流板结构参数的确定提供了依据. 工业应用的标定结果表明分离器压降预测式是准确的,它可用于工业气液分离器的放大设计.