CFBC旋风分离器气固两相流

discussion of the near wall treatment and simply standard wall approach is utilized.However main purpose of this tutorial is to show how to relatively easy create structured mesh for the geometry which automatic mesh generator are not able to handle such meshes.One can try to build geometry with different heater alignments and observe how that influence,theflow,pressure drop,and temperature profile at the outlet of the heater.0.2Cyclone.In many industrial processes emerge a need of cleaning gases from dispersed inert particles suspended within gas(eg.removal offlying ash fromflue gases in industrial coalfired boilers).Easiest and most commonly used method of separation takes advantage of gravitation forces.Device which work on this basis is a cyclone.With this tutorial we build simple cyclone geometry,mesh it, and run Fluent simulations.Instead offlue gases we will use air stream polluted with ash.Data for boundary conditions are given in Table2.airflow0.27m3n/sairflow temperature500Cash massflux0.001kg/smin.particle diameter1µmmax.particle diameter300µmmean particle diameter150µmspread parameter 2.8ash density2100kg/m3Table2:Cyclone running parameterFigure9shows cyclone dimensions.Geometry of the cyclone is build in Gambit using volume primitives.Figure10shows all volumes used to build the cyclone which are connected using boolean operations.0.2.1Building geometryProcedure of building the cyclone geometry is very simple.First we create and move in the right position volume primitives presented in Figure10.Next boolean summation and subtraction is used to unite all primitives in order to create one volume representing a cyclone.See below listing of the geometry cre-ation procedure.Listing shows order of operations to be carried out in Gambit. Geometry→Volume→Create Volume→CylinderEnter Height=0.5,Radius1=0.3,Radius2=0.3press Apply11Figure9:Cyclone dimensions. Geometry→Volume→Create Volume→FrustumEnter Height=1.0,Radius1=0.3,Radius2=0.3,Radius3=0.1 press ApplyGeometry→Volume→Move/Copy/AlignSelect with the mouse created frustum:Pick Volume2Check Move,TranslateEnter X=0,Y=0,Z=0.5press ApplyGeometry→Volume→Create Volume→CylinderEnter Height=0.05,Radius1=0.1,Radius2=0.112Figure10:Volume primitives for Cyclone.press ApplyGeometry→Volume→Move/Copy/AlignSelect with the mouse created cylinder:Pick Volume3 Check Move,TranslateEnter X=0,Y=0,Z=1.5press ApplyGeometry→Volume→Create Volume→CylinderEnter Height=0.15,Radius1=0.2,Radius2=0.2press ApplyGeometry→Volume→Move/Copy/AlignSelect with the mouse created cylinder:Pick Volume413Check Move,TranslateEnter X=0,Y=0,Z=1.55press ApplyGeometry→Volume→Create Volume→CylinderEnter:Height=0.8,Radius1=0.1,Radius2=0.1press ApplyGeometry→Volume→Move/Copy/AlignSelect with the mouse created cylinder:Pick Volume5Check Move,TranslateEnter X=0,Y=0,Z=-0.2press ApplyGeometry→Volume→Create Volume→BrickEnter Width=0.2,Depth=0.7,Height=0.2press ApplyGeometry→Volume→Move/Copy/AlignSelect with the mouse created cylinder:Pick Volume6Check Move,TranslateEnter X=0.2,Y=0.35,Z=0.1press ApplyGeometry→Volume→Boolean Operations→UniteSelect with the mouse all the volumes except last created(Volume6):Pick Vol-ume1,Volume2,Volume3,Volume4,Volume5press ApplyGeometry→Volume→Boolean Operations→SubtractSelect with the mouse the volumes which is result of last operation:Volume Volume1Select with the mouse remaining volume:Subtract Volume Volume5Check Retain under Subtract Volumepress ApplyGeometry→Face→Connect/Disconnect Faces→ConnectSelect with the mouse faces aligned between volumes,only this which are at the cover of small cylinder,seefigure11.This operation is needed to force continuum between volumes.It results in deleting one of the face which are aligned at the same position.After operation two volumes are linked by one face forcing later the same mesh to be generated for both volumes at that face. Not connected faces will be by default treated as wall.In our case,side cylinder face of the Volume5will be a wall.press Apply after making selection14Figure11:Faces to be selected for Face Connect oparation.0.2.2Setting boundary condition typesIn order to indicate inlet and outlet of the cyclone we need to specify boundary condition types in Gambit.Additionally ash hopper has to be marked as sepa-rate wall,this is required for dispersed phase modelling.See listing of boundary types setting below.Zones→Specify Boundary TypesCheck(Add)Enter,Name:inSelect Type VELOCITY INLETPick Entity:Faces,face representing inlet to the cyclone,see Figure12press ApplyZones→Specify Boundary TypesCheck(Add)Enter,Name:outSelect Type OUTFLOWPick Entity:Faces,face representing outlet from the cyclone,see Figure12 press Apply15Zones →Specify Boundary Types Check (Add )Enter,Name:ash Select Type WALLPick Entity :Faces ,faces creating ash hopper,see Figure 12pressApplyFigure 12:Boundary condition types.0.2.3Meshing geometryGeneration of appropriate mesh for cyclone geometry is not a trivial task.The flow inside a cyclone is fully 3dimensional and complex.Proper simulation of such flow require careful treatment of the mesh.Since this exercise is only to show possibilities of Fluent and we rather would like to show general procedure of simulating cyclone operation automatic mesh generator will be used.It is advised never to use shown here mesh for simulations of real object.See below16procedure for meshing cyclone geometry.Mesh→FacePick Faces,select all the facesSelect Elements:TriSelect Type:PaveCheck Spacing:ApplyEnter Interval size0.05Press ApplyMesh→VolumePick Volumes,select all the volumesSelect Elements:Tet/HybridSelect Type:TgridUncheck Spacing:ApplyPress ApplyFinal mesh should contain around20000cells.The last task to perform in Gambit is to export generated mesh to thefile.File→Export→MeshPress Browse to select destination folder.Enter name of thefile,extension will be given by default.Press Accept0.2.4Setting Fluent parametersHerewith procedure of setting up cyclone simulations in Fluent.Read meshfile(meshfiles have extension˙msh)created in previous section. File→Read→Case...Define solver settings as default.Define→Models→Solver...Set turbulence modellDefine→Models→Viscous...Select k− RNG turbulence model with option Swirl Dominated FlowIn the Discrete Phase Model panel change Maximum Number of Steps to10000 Set InjectionsSelect Injection Type→surfaceSelect Release From Surfaces→in(in is an inlet face)Select Material→ashSelect Diameter Distribution→rosin-rammler-logarithmicSelect tab Point PropertiesEnter Total Flow Rate(kg/s)equal to0.001Enter Min.Diameter(m)equal to1e-6Enter Max.Diameter(m)equal to300e-617Enter Mean Diameter(m)equal to150e-6Enter Spread Parameter equal to2.8Enter Number of Diameters equal to15Select tab Turbulent DispersionFrom Stochastic Tracking select Discrete Random Walk ModelEnter Number of Tries equal to5Accept settings pressing OKDefine material properties Define→Materials...Change density for airEnter Density(kg/m3)equal to1.094Confirm changes pressing Change CreateChange density for inert-particle ashEnter Density(kg/m3)equal to2100Confirm changes pressing Change CreateDefine operating condition Define→Operating Conditions...Select GravityEnter gravitation acceleration Z(m/s2)equal to9.81Accept settings pressing OKDefine boundary condition Define→Boundary Conditions...Select Zone→in,press SetEnter Velocity Magnitude(m/s)equal to7.98Select Turbulence Specification Method→Intensity and Hydraulic Diameter Enter Hydraulic Diameter(m)equal to0.2Accept settings pressing OKSelect Zone→ash,press SetSelect tab DPMUnder Discrete Phase Model Condition select Boundary Cond.Type→trap Accept settings pressing OKSelect Zone→wall,press SetSelect tab DPMUnder Discrete Phase Reflection Condition select Normal→constantEnter value equal to0.8Under Discrete Phase Reflection Condition select Tangent→constantEnter value equal to0.8Accept settings pressing OKClose Boundary Condition panelset up solver parameters Solve→Controls→Solution...From Discretization select Momentum→Second Order UpwindFrom Discretization select Turbulent Kinetic Energy→Second Order Upwind From Discretization select Turbulent Dissipation Rate→Second Order Upwind Accept settings pressing OKInitialize solution Solve→Initialize→Initialize...Press Init and close Solution Initialization panelSet solution monitoring option Solve→Monitors→Residual...Under Option select PlotFor Residual→continuity→Convergence Criterion enter value equal to10e-918Accept settings pressing OKsave Fluent settings parameter in casefile(casefiles have extension.cas)File →Write→Case...,enterfile name and accept settings pressing OK0.2.5Performing calculationsHerewith we assume that Fluent is open and casefile with cyclone is read. Type in Fluent command window it100,(this command executes100iterations) Observe in Fluent result window residuals of the solved equationsCreating planes for extracting calculated variablesRunning simulations on3D domain we do not have direct access to solved vari-able inside the ing Fluent post processing tools we can display only variables on the external boundary of the domain.In order to access variable inside the domain internal lines or planes needs to be created.The best of the flow visualization is to look at variables(velocity,pressurefield)on the plane inside the domain.Planes can be placed at arbitral position selected by the user.From the number of methods of defining planes position available in Flu-ent we suggest to use3points method described below.Just in case we do not remember size of the domain geometry and its placement in the cartesian system we can display cartesian coordinates on the external boundaries of the domain geometry(see listing below).Select Display→Contours...From Option select FilledFrom Contours of select Grid→X-coordinateFrom Surfaces select wallPress DisplayObserve in Fluent result window boundary of the domain colored by X cartesian coordinateRepeat operation for Contours of→Y-coordinate and Z-coordinateThe cyclone axis is aligned with Z axis and crossing X=0and Y=0cartesian coordinates.Now we create plane crossing cyclone for Y=0.Select Surface→Plane...From Points enter,x0(m)=1,x1(m)=0,x2(m)=0y0(m)=0,y1(m)=0,y2(m)=0z0(m)=0,z1(m)=0,z2(m)=1(exact coordinates are not important,points can not be aligned,and in our case all y variables must be equal to0)19For New Surface Name enter desired name of the surface and press Create Close Plane Surface panel pressing CloseYou can repeat procedure above to create more planes in the arbitral positions inside analyzed domain.You can see created planes by displaying them in the Fluent result window.Select Display→Grid...Select All from Edge TypeFrom Surface select name of the creates palnePress DisplayDisplaying Fluent variables on created planesFluent provide extremely powerful post processing tool.It allows to display on the screen all calculated variables and number of predefined derivatives of these variables.Here we show general procedure of displaying variables on created planes.Select Display→Contours...From Option select FilledFrom Contours of,select Pressure...→Static PressureFrom Surfaces select plane created in previous stepPress DisplayObserve in Fluent result window plane colored by static pressurefield,one can see that the boundary of the domain are not visible,From Option select Draw Grid panel Grid Display pop upsFrom Edge Type select Feature,and from Surfaces select domain boundary you want to displayPress Display,now,when displaying contours of variables simultaneously domain boundary wireframe will be displayedFrom Contours of,select Velocity...→Velocity MagnitudePress DisplayObserve in Fluent result window plane colored by velocity magnitudefield,and the boundary of the domainSimulating ashflying inside a cyclone-particle trackingIn most of the cases mass load of the inert particles is small comparing to trans-port gas.If heat transfer between phases in not involved particle can be,without considerable error,traced within a gas phase in the frame of postprocessing.It means thatfirst we simulatefluidflow of a gas phase.When convergence for continues phase is reached inert particle representing ash are traced employing20Lagrangian model.See below for executing tracing procedure.Select Display→Particle Tracks...From Option activate Draw Grid in order to see boundary of the domain(see section above for explanation)From Release from Injections select injection-0,(name can be different)Select Track Single Particle Stream,(number of particle traced usually exceed thousands and tracking procedure in lengthly even on fast computers,in orderto make this faster and be able to see particle paths on the screen we select this option→particle will be send only from one face at the inlet)Press Display,(Fluent starts tracing procedure,afterfinishing displays particle paths in results window.In the main Fluent window report of the tracing procedure is printed.Report shows how many particles have been traced,trapped,escaped,aborted and in-complete,evaporated for inert particle is meaningless.Trapped are particle col-lected in the ash hopper.Escaped are these which left the cyclone through the outlet.Aborted are not traced by the solver due to numerical error.Incomplete are these for which Max.Number of Steps was not enough to complete tracing. See section0.2.4for changing Max.Number of Steps for particle tracking.) Useful option in particle tracking procedure is summary report.It can helpin assessing efficiency of cyclone which is calculated as ratio of the ash massflux collected inside ash hopper to the ash massflux entering a cyclone.It also informs of the massflux of incomplete traces.The regular report provide only the number of trapped,escaped and incomplete streams which is meaningless in assessing cyclone operation.See procedure below for activating summary report. Within Particle Trucks panel,select Summary from Report TypeDeselect Track Single Particle StreamPress Track,(particle steams will not be displayed in results window)See below example of summary report:number tracked=3300,escaped=419,aborted=0,trapped=2362,evaporated=0,incomplete=519Fate Number Elapsed Time(s)Injection,IndexMin Max Avg Std Dev Min Max ------------------------------------------------------------------------------------------Incomplete519 5.646e-001 4.080e+000 1.130e+000 3.826e-001injection-00injection-0515 Trapped-Zone423627.418e-001 3.770e+000 1.509e+000 3.425e-001injection-0424injection-0203 Escaped-Zone5419 3.792e-001 3.530e+000 1.003e+000 5.647e-001injection-048injection-0275 (*)-Mass Transfer Summary-(*)Fate Mass Flow(kg/s)Initial Final Change----------------------------------Incomplete 2.897e-008 2.897e-0080.000e+000Trapped-Zone49.996e-0049.996e-0040.000e+000Escaped-Zone5 3.562e-007 3.562e-0070.000e+000The most interesting is Mass Transfer Summary which shows massfluxes of Incomplete,Trapped and Escaped particle streams.General report shows only number of incomplete,trapped and escaped particle stream.Sometimes even21large number of escaped particle streams not impose low cyclone efficiency, because these streams could be low diameter particle streams.Hence in order to asses cyclone efficiency massfluxes of trapped and escaped particle streams needs to be compared.Escaped particle stream number indicate how many trace of the particle streams has not been completed.There are neither trapped nor escaped and traced has beenfinished inside domain.If number and massflux of incomplete stream is large we need to increase Max.Number of Steps under Discrete Phase Model panel opened from Define menu.22。

CFB锅炉冷却型旋风分离器浅谈喆刘昕（中石化镇海炼化分公司，浙江 宁波 315207）摘要：旋风分离器是循环流化床锅炉的重要部件，是影响循环流化床锅炉稳定运行的重要因素之一。

它的分离效率是评定的必要条件，而稳定性则关系到锅炉内外物料循环的控制与调节。

关键词：循环流化床；旋风分离器；工作原理；影响；改造1 设备简介某公司公用工程部二电站采用的是汽冷旋风分离器, 其工作原理是气固混合物通过矩形导管切向进入旋风筒，旋风分离器的圆形筒体和气体的切向入口使气固混合物进入围绕旋风分离器的两个同心涡流.外部涡流向下，内部涡流向上，由于固体密度比烟气密度大，在离心力作用下，固体离开外部涡流移向壁面分离的固体沿壁面滑下，在旋风分离器的锥形段底部堆积,再从底部流进循环流化床回路循环管道,相对干净的气体通过内部涡流向上移动，经旋风分离器的顶部的中心，垂直出口离开，中间采用蒸汽冷却。

随着长久使用，设备慢慢的发生了变化，二电站1#锅炉因为旋风分离器清理过大块挂壁结焦物，导致目前床温明显低于另外一台,在850～860度;通过定期的飞灰取样分析，数据表明1#锅炉飞灰中的碳含量明显低于2#，可以证明1#旋风分离器的效果相对较好，就是由于其分离效果太好，导致了目前的现状，下文将具体分析。

2 旋风分离器特点与分析2.1 汽冷式旋风分离器的优点由于汽冷式旋风分离器内壁有较薄的耐磨层，因此防磨层内外壁温差小，抗热冲击能力强，防磨层不易产生裂纹、不易脱落，可靠性高。

对负荷变化、温度变化适应能力强，且汽冷式分离器可有效地吸收循环物料的热量，提高蒸汽温度，降低循环灰温度，避免分离器内二次燃烧，回料器内结焦，影响锅炉连续可靠运行。

并且汽冷式分离器与炉膛之间胀差小，结构简单，具有更可靠的密封性，不漏灰。

2.2 旋风分离器的效率与锅炉负荷及物料循环量的的关系当旋风分离器的效率太高了,其回料量就多了,同时反料中的飞灰量也就多了,其产生的排烟热损失自然也就多了,床温就会下降,导致负荷上升,物料循环量自然也会上升。

旋风分离器气固两相流数值模拟及性能分析共3篇旋风分离器气固两相流数值模拟及性能分析1旋风分离器气固两相流数值模拟及性能分析旋风分离器是一种广泛应用于化工、环保、电力等领域的气固分离设备，其利用离心力将气固两相流中的颗粒物分离出来，一般被用作除尘和粉尘回收设备。

本文将介绍旋风分离器的气固两相流数值模拟及性能分析。

气固两相流是指气体与固体颗粒混合物流动的状态。

旋风分离器中的气固两相流在进入设备后，经过导流装置后便会进入旋风筒，此时气固两相流呈螺旋上升流动状态，颗粒物受到离心力的作用被抛向旋风筒壁，而气体则从旋风筒顶部中心脱离，从出口排放。

因此，旋风分离器气固两相流的流体物理特性显得尤为重要。

本文采用计算流体力学（Computational Fluid Dynamics，CFD）方法对旋风分离器气固两相流进行数值模拟。

对于气体流动部分，采用了二维轴对称的控制方程式，包括连续性方程、动量方程和能量方程，而对于颗粒物流动部分，采用了颗粒物轨迹模型（Particle Tracking Model，PTM）。

在数值模拟过程中，采用了FLUENT软件进行求解，其中的数值算法采用双重电子数法（Electron Electrostatic Force Field，E3F2）。

数值模拟结果显示，在旋风分离器中，气体的流速主要集中在筒壁附近，而在离筒中心较远的地方，则流速较慢，颗粒物则以螺旋线的方式向旋风筒壁移动，并沿着筒壁向下运动。

颗粒物在旋风筒中受到离心力的作用后，其分布状态将随着离心力的变化而变化，最终沉积在筒壁处。

数值模拟结果还表明，旋风分离器的分离效率随着旋风筒直径的增加而增加。

为了验证数值模拟结果的可信度，实验室制作了一个小型旋风分离器进行了实验研究。

实验结果表明，数值模拟与实验结果相比较为一致，通过数值模拟可以较好地描述旋风分离器中气固两相流动的情况并用于性能预测。

综合来看，数值模拟是一种较为有效的旋风分离器气固两相流性能分析方法，可以较好地预测旋风分离器的分离效率和颗粒物的分布状态，为旋风分离器的设计和优化提供了有力支持综上所述，本文利用数值模拟方法和实验研究相结合的方式，对旋风分离器的气固两相流动性能进行了分析。

CHENGSHIZHOUKAN 2019/15城市周刊90催化旋风分离器机械故障的原因分析连　仲　中国石油抚顺石化公司石油二厂罗　茜　中国石油抚顺石化公司烯烃厂摘要：近些年来，随着经济发展，现代化建设水平也突飞猛进。

催化裂化装置旋风分离器的操作条件比较苛刻，其温度比较高、分离催化剂的浓度大。

旋风分离器在长时间运行过程中承受各种机械载荷、高温和压力载荷、介质腐蚀，尤其是颗粒的冲蚀和摩擦等作用，某些零部件的功能不可避免会逐渐失效，最后发生各种各样的机械故障，例如冲蚀、磨损、断裂、堵塞等。

这些故障是影响催化裂化装置长周期运行的主要因素之一。

当旋风分离器发生机械故障后，主要的表现形式是分离效率下降，出口催化剂浓度上升，催化剂跑损量增大，压力降和压力也随之发生变化。

这些外部的表现形式与机械故障之间存在着直接的联系，可以通过旋风分离器跑损催化剂的浓度、粒度变化、入口速度和压力降的增大或减小、压力的波动等，对故障做出诊断，确定产生故障的原因和位置，为后续故障的消除提供支持。

关键词：催化旋风分离器；机械故障；原因分析催化裂化工艺中旋风分离器被用来进行催化剂与油气或与烟气的分离，是保证催化裂化装置长周期安全稳定运行的主要设备。

旋风分离器在高温和高浓度的环境下长时间工作有可能发生各种机械故障，例如冲蚀、磨损、断裂、堵塞等，这些故障是导致分离效率下降，催化剂跑损量增大，压力降减小等的主要原因之一。

这些不同的机械故障所引起的操作参数变化和跑损催化剂的物性变化是有所不同的，有些参数是突变的，有些是渐变的，还有一些是波动变化的，这些变化与机械故障之间存在着密切联系。

可以通过跑损催化剂的浓度和粒度的变化，旋风分离器入口速度和压力降的变化对旋风分离器产生机械故障的原因进行诊断和分析。

一、机械故障和催化剂跑剂催化裂化旋风分离器系统通常是由多组多级并联旋风分离器、翼阀料腿、吊柱和拉杆支架等构成。

旋风分离器系统长期处于高浓度气固两相流的流动环境中，一方面承载着不稳定两相流的诱导振动，另一方面受到流动颗粒的冲蚀磨损。

旋风分离器在工业上的应用已有百年多的历史。

它是利用气固两相流的旋转，将固体颗粒从气流中分离出来的一种干式气-固分离装置[1]。

与其它气固分离设备相比，具有结构简单、设备紧凑、性能稳定和分离效率高等特点。

广泛应用于石油、化工、冶金、建筑、矿山、机械和环保等工业部门。

由于旋风分离器内部流动非常复杂，用试验或者解析的方法研究分离器内部的流动状况比较困难。

近年来，随着计算机硬件及CFD(计算流体动力学)技术的不断进步[2,3]，数值方法成为研究旋风分离器的一种重要手段。

通过对旋风分离器内气固两相进行数值模拟，揭示旋风分离器内部流场，为优化旋风分离器的结构提供思路，也为进一步提高分离性能奠定基础。

1旋风分离器的结构和工作原理一般来说，旋风分离器由进气管、柱段、锥段、排气管和集灰斗等部分组成（图1）。

含尘气流以12m/s ～25m/s 的速度从进气口进入旋风分离器，气流由直线运动变为圆周运动，产生高速旋转的涡旋运动。

旋转气流中的固体颗粒由于离心加速度的作用，向器壁运动，接触器壁后失去惯性力而靠入口速度的动力和向下的重力沿器壁螺旋形向下，经锥段排入灰斗中。

向下旋转的净化气体到达锥段下部某一位置时，由于负压作用，便以相同的旋转方向在分离器内部由下而上螺旋运动，经排气管排出旋风分离器外。

2旋风分离器流场数值模拟研究进展虽然旋风分离器结构简单，但是其内部的三维旋转湍流流场却相当复杂。

工程应用对该流场的数值模拟，基本上是基于求解Reynolds 时均方程及关联量输运方程的湍流模拟方法。

描述湍流运动的数学基础仍然是连续性方程和瞬时N -S 方程。

连续性方程：N -S 方程：收稿日期：2012-04-11；作者简介：韩婕（1984-），女，电邮hanjie854@ 。

旋风分离器两相流动数值模拟研究进展韩婕，刘阿龙，彭东辉，吴文华（上海化工研究院化学工程及装备研究所，上海200062）摘要：介绍了旋风分离器的结构与工作原理，综述了国内外旋风分离器两相流场的数值模拟研究进展，对研究过程所用的研究方法进行了描述，分析比较了研究成果。

气固分离装置气力输送是气固两相流体，输送到尾端时固体散料落进接收设备而气体则排空或者回收再利用，这就需要气固分离设备将固体散料与气体分离开来。

1，正压输送系统所用气固分离装置：是指低中压稀相正压输送和高压密相正压输送，气固分离装置包括布袋除尘器、旋风分离器、沉降式大型料仓（惯性除尘器）、湿法洗涤除尘设备，以上这些设备都是除尘系统的专用设备，气力输送系统中所使用的气固分离设备则借用了这些除尘系统的专用设备，也就是说气力输送中所使用的气固分离设备就是使用了没有经过任何改动的布袋除尘器、旋风分离器、惯性除尘器和湿法洗涤除尘设备。

1.1气固分离装置工作原理：A，布袋除尘器：以针刺毡布袋过滤粉尘，通常采用脉冲反吹进行清灰，详见附录，布袋属于深层过滤，也就是类似“棉被”，粉尘进入“棉被”内部达到一定数量后，“棉被”就会形成依靠粉尘过滤的过滤层将粉尘阻挡在布袋的外面，气体则穿过布袋而排空，以此达到气固分离之目的。

布袋除尘器的处理风量能力正比于其布袋总过滤面积，一般每平方米过滤面积所对应的能够处理输送风量为15~60 Nm3/h，如果粉尘浓度高应该适当加大过滤面积。

如果超细粉尘含量多则应该选择覆膜布袋或加厚布袋。

B, 旋风分离器：含物料的气固两相流体切向进入旋风分离器的圆形筒体，由于离心力的作用密度大的物料流会沿着圆形筒体的内壁旋转并一边旋转一边逐渐下落并由筒体的底部排出，而密度小的气体则被挤压到中部，气体一边旋转一边逐渐上升并由上口排空，以此达到气固分离之目的。

风量不变时增大旋风分离器的直径则离心力减小旋风分离效果变差。

旋风分离器的直径减小则处理量变小且大量物料短路从排空口排出跑灰。

因此使用旋风分离器时其尺寸必须适合所需处理的风量。

具体尺寸应该参考“除尘设备”书籍有关旋风分离器章节选取。

旋风分离器的进口风速一般在10-15米每秒，风速太高则出现混乱的扰流失去依靠离心力进行气固分离的作用，风速太低则离心力减小旋风分离效果变差。

循环流化床锅炉一、循环流化床锅炉概述循环流化床锅炉是一种高效、低污染的新型清洁燃烧设备，它与其他类型的锅炉主要区别在于燃烧方式不同，即炉内燃料在燃烧配风的作用下处于一种特殊的运动状态——流化状态，炉内湍流运动强烈，燃料及脱硫剂经多次循环，反复地进行低温燃烧和脱硫反应，不但能达到低NO X排放、90%的脱硫反应效率和与煤粉炉相近的燃烧效率，而且具有燃烧适应性广、负荷调节性能好、灰渣易于综合利用等优点。

主要优点：1、燃料适应性广2、有利于降低污染气体排放850~950℃有利于脱硫还可以抑制热反应型氮氧化物的形成，由于是分段送人二次风，可以抑制燃料型氮氧化物的产生，NO X的形成量仅为煤粉炉的1/4~1/3。

3、负荷调节性能好（30%~110%）4、灰渣综合利用性能好CFB锅炉燃烧温度低，灰渣不会软化和黏结，活性较好，可用于制造水泥的掺和料或其他建筑材料的原料。

主要缺点：1、大型化问题收技术和辅助设备的限制，与煤粉炉相比，目前CFB锅炉的单机容量还偏小，无法在火力发电领域成为主力炉型2、烟—风系统阻力较高，风机用电量大因为CFB锅炉布风板及床层阻力大，而烟气系统中又增加了气固分离器的阻力，所以烟风系统阻力高。

CFB锅炉需要的风机压头高，风机数量多，故风机用电量大，这会增加电厂的生产成本。

3、自动控制较难实现由于影响CFB锅炉燃烧状况的因素较多，各型锅炉调整方式差异较大，所以采用计算机自动控制比常规锅炉难得多。

4、磨损问题CFB锅炉的燃料粒径较大，并且炉膛内物料浓度是煤粉炉的十到几十倍。

虽然采取了许多防磨措施，但在实际运行中CFB锅炉受热面的磨损速度仍比常规锅炉大得多，受热面磨损问题可能成为影响锅炉长期连续运行的重要原因5、对辅助设备要求高（高压风机、冷渣器的性能和运行问题）6、理论技术问题CFB锅炉虽然已有千余台投入运行，但仍有许多基础理论和设计制造技术问题没有根本解决。

至于运行方面，还没有成熟的经验，更缺少统一的标准，这给电厂设备改造和运行调试带来了诸多困难。

硕士学位论文旋风分离器气固两相流数值模拟及性能分析NUMERICAL SIMULATION AND PERFORMANCE ANALYSIS OF GAS-SOLID TWO PHASE FLOW IN CYCLONE SEPARATOR汪 林哈尔滨工业大学2007年7月国内图书分类号：TU834.6国际图书分类号：626工学硕士学位论文旋风分离器气固两相流数值模拟及性能分析硕士研究生：汪林导师：朱蒙生 副教授申请学位：工学硕士学科、专业：水力学及河流动力学所在单位：市政环境工程学院答辩日期：2007年7月授予学位单位：哈尔滨工业大学Classified Index: TU834.6U.D.C: 626Dissertation for the Master Degree in EngineeringNUMERICAL SIMULATION AND PERFORMANCE ANALYSIS OF GAS-SOLID TWO PHASE FLOW INCYCLONE SEPARATORCandidate:Supervisor:Academic Degree Applied for: Speciality:Affiliation:Date of Defence:Degree-Conferring-Institution:Wang LinAssociate Prof. Zhu Mengsheng Master of Engineering Hydraulics and River Dynamics School of Municipal & Environmental Engineering July, 2007Harbin Institute of Technology摘要摘要近年来，随着人们环境保护意识的加强，以旋风分离器为代表的各类除尘设备已经成为防治大气污染的主力军，在消除大气污染、保障人类健康及生态环境方面发挥着重要作用。