催化剂氢气提升管冲蚀磨损数值研究b外文翻译

1、外文翻译毕业设计题目： 催化剂氢气提升管冲蚀磨损数值研究 原文 1：Ming solid particle erosion in elbows andplugged tees译文 1：弯管和盲三通中的的颗粒冲蚀模型原文 2：The impact angle dependence of erosion damagecaused by solid particle impact译文 2：固体颗粒侵蚀造成的冲击损伤影响的角度依赖性Ming Solid Particle Erosion in Elbows and Plugged TeesPredicted erosion patterns on th

2、e surface of a pipe fitting can now be obtained using atechnique implemented into a computational fluid dynamics (CFD) code. This comprehensiveerosion prediction procedure consists of 1) generation of a flow field simulation,2) computation ofa large number of particle trajectories inside the flow fi

3、eld, and3) erosion mequations appliedas particles impinge the walls of the geometry. Other quantities related to erosion, namely theparticle deposition rate as well as local average impingement angle and velocity components, arealso stored in the procedure. All predicted quantities (flow solution, p

4、article trajectories, anderosion profiles) are analyzed using a three-dimensional visualization tool that was also developed.The current work focuses on two pipe fittings commonly used in the oil and gas productionindustry: elbows and plugged tees. First, the flow field and erosion predictions are e

5、valuatedthrough comparisons with experimental data. Erosion predictions yield trends and locations ofum wear that are consistent with experimental observations. Next, two 90-deg pipe elbowswith centerline curvature-to-diameter ratios of 1.5 and 5.0 are analyzed under prescribed erosiveconditions. Pr

6、edicted erosion results are presented in the form of surface contours. Finally, asimulated plugged tee geometry placed under erosive conditions is studied and erosion rates arecompared to that of the two elbow test cases.IntroductionSolid particle erosion can be a major concern in the production and

7、 transport of petroleumfluids. Entrained solids such as sand particles impinge the inside surfaces of pipes, valves, fittings,and other system components, causing mechanical wear and eventual failure of these devices.Nearly every fluid transport system contains components that are susceptible to ero

8、sion by solidparticles. This phenomenon can be extremely costly, requiring frequent replacement ofcomponents as well as system down time. Certain geometries are more susceptible to erosiondamage than others. For example, fittings such as elbows and tees that redirect the flow field canexperience sev

9、ere erosion under certain conditions.The thrust of this work is to evaluate the performance of elbow and plugged tee geometries inerosive service. These geometries are of particular interest due to their frequent use in oil and gasproduction. Particles entrained in the produced fluid can cross fluid

10、 streamlines and impinge thewalls of the fitting. Particle impingements on the pipe wall can remove wall material causing it tobecome thinner with time, eventually resulting in failure.In order to keep operating costs and system down time at a minimum, it is necessary to combatsand erosion. One way

11、of controlling erosion is to select operating conditions such as flow ratesthat limit erosion to acceptable levels. In addition, wise selection of pipe materials can assist inerosion control. Under highly erosive conditions, alternative methods of erosion control must beemployed. In many cases, a pl

12、ugged tee geometry is installed to accommodate extremely erosiveenvironments. It is anticipated that the layer of nearly stagnant fluid in the plugged section of thegeometry provides a cushion for impinging particles, resulting in significantly reduced amounts oferosion damage.The current research p

13、roject focuses on the application of an erosion prediction procedure thatmakes use of a commercially available computational fluid dynamics (CFD) code. The erosionprediction procedure is designed for use with CFX, developed by AEA Technologies, Inc. CFX isa three-dimensional flow field solver that a

14、lso contains the Lagrangian particle tracking mused in this study. This erosion prediction procedure can be used to better understand howparameters such as inlet conditions, fluid properties, flow rate, particle size and concentration, andgeometry, affect erosion behavior.BackgroundTwo geometries of

15、 particular interest are elbows and plugged tees since they are commonlyused in piping systems. In an elbow, the curved walls of the geometry change the flow direction.Particles can cross fluid streamlines and impinge the walls of the fitting. When erosion rates arelarge, a plugged tee is often subs

16、tituted for an elbow. The reason is that the nearly stagnant regionin the plugged branch of the tee may provide a cushion for incoming particles and thus reducethe erosion rate.Previously, experimental work was performed on elbows and plugged tees; for example, seeBourgoyne and Tolle and Greenwood.

17、However, it is not clear under what conditions it isadvantageous to employ a plugged tee in erosive service. Furthermore, questions regarding theoptimum dimensions of a plugged tee for a given set of flow conditions remain unaddressed. Thus,CFD simulations are being performed in order to help identi

18、fy important parameters that affecterosion in these complex geometries.Investigators are interested in being able to accurately predict erosion behavior for a widerange of geometries and flow conditions. Some simple erosion ms are available for a fewfittings such as elbows and tees. For example, Shi

19、razi. and Sadeveloped simple msto predict erosion in elbows. In another study, Wang et al. used flow ming and particletracking to study the effects of elbow curvature on erosion rates. Nearly all currently availablems only consider erosion as a result of direct impingement; the effects of turbulentf

20、luctuations on elbow erosion are not considered.In the study of particle-fluid interaction and the resulting particle wall impingements, one candistinguish two categories of particle impingements, as depicted in Fig. 1. These two categoriesare: 1) direct impingement, and 2) Random impingementFig.1 D

21、irect and random impingement mechanismsFig.2 Nomenclature for elbow and plugged-tee geometriesmechanisms. If erosion is caused primarily by a direct impingement mechanism, this states thatthe particles tend to be driven to the walls primarily by the momentum of the particle resultingfrom the mean fl

22、ow velocity. Direct impingements can be the dominant type when the particlesare large and dense as compared with the carrier fluid density, or where viscous effects are small,as in the case of sand in air. When velocity fluctuations due to turbulence affect particle motionand cause impingements, the

23、 term random is used to describe the impingement mechanism.Particle impingements that occur in a straight pipe are solely due to the random impingementmechanism. In a straight pipe, even though there is no mean velocity component in the radialdirection that directs particles toward the walls, partic

24、les still impinge since they are affected byturbulent eddies. These eddies can transfer radial momentum to the particles near the wall andcause random impingements.Figure 2 defines the geometry and nomenclature for the elbow and plugged tee geometriesstudied in this work. For the elbow, with diamete

25、r D, the inner and outer wall curvatures aredenoted by ri and r0 , respectively, and the centerline turning radius is denoted by r. Forpresentation of flow field results, the distance from the inner wall is assigned the value h. Thedistance, either upstream or downstream, of the bend is denoted by x

26、. For the plugged teegeometry, also shown in Fig. 2, the pipe diameters are taken to be D1 , D2 , and D3 as shown. Forthe plugged tee geometry considered in this work, all three pipe sizes are equal in diameter.MDescriptionTeralized erosion prediction procedure consists of three separate ms or simul

27、ations:1)flow ming, 2)tracking of a large number of sand particles, and 3)application of empiricalerosion equations. CFX contains the ability to couple the equations governing fluid motion and theparticle equation of motion. This ability has not been employed in this work due to the lowparticle conc

28、entrations that are used.The flow simulation contains the information necessary to perform all subsequent calculations.Velocity components, turbulence quantities (turbulent kinetic energy and dissipation rate), as wellas the carrier fluid properties (density and viscosity) are all contained within t

29、he flow fieldsimulation. Once a simulated flow field is obtained using the CFD code, the solution is seededwith a large number of sand particles at the inlet to the geometry. A large number of particles, onthe order of several thousand, is normally required in order to obtain a reasonable distributi

30、on andto reduce scatter in the erosion predictions. Each particle is tracked separately through the flowfield and particle impingement information (velocity and location) is gathered as particles strikethe walls. For each particle impingement, a set of empirical erosion equations is applied. Thesere

31、lations are used to determine the mass loss resulting from that impingement. These erosionequations account for the impingement speed and angle, as well as the particle shape andmechanical properties of the wall material.In order to visualize erosion predictions in a convenient manner, predicted ero

32、sion data istransferred to a postprocessor. This postprocessor is used to generate contour plots of predictederosion quantities. This allows not only the simultaneous examination of the flow solution,particle trajectories, and erosion predictions, but also provides the ability to identify areas of h

33、igherosion.Flow M. The flow simulation is obtained through use of a commercially availablecomputational fluid dynamics (CFD) code. The code employed in this work is CFX, developed byAEA Technology, Inc. CFX utilizes a finite-volume, multi-block approach to solve the governingequations of fluid motio

34、n numerically on a user-defined computational grid. AEA Technology andPatankar describe the procedure that is used to solve the equations of fluid motion.The flow solution procedure consists of first generating the computational grid. Apre-processor is available in the software that is used to perfo

35、rm this task. Second, solutionoptions such as inlet and boundary conditions, turbulence m, and discretization scheme, arespecified. The final step is running the flow solver to generate the actual flow field simulation.CFX contains several ms for turbulence behavior. Isotropic and nonisotropic turbu

36、lencems are available. In addition, a multitude of discretization schemes are available to obtain themost accurate flow solution possible. Edwards. address the choice of turbulence manddiscretization scheme for both 2-D and 3-D simulations and their effects on the accuracy of theflow field solution.

37、 For this work, a differential Reynolds stress turbulence mand a quadraticupwind discretization scheme were used unless stated otherwise. The quadratic upwinddiscretization scheme is third order for convective terms and second order for diffusion terms.Particle Transport M. The CFD code contains a L

38、agrangian particle tracking algorithmthat numerically predicts trajectories of solid particles, droplets, or bubbles through the flow field.These calculations use information generated by the flow field simulation. The code also has thecapability to couple the particle equation of motion with the fl

39、ow solution. Coupling the governingequations for the fluid and the particles allows effects such as fluid displacement by particles andparticle-induced turbulence to be investigated. In many cases of engineering interest, especiallyliquid/solid flows, this coupling allows the investigation of partic

40、le concentration effects.However, at low particle concentrations, the particles do not affect the flow and this coupling isnot necessary.The equations for the rate of change of velocity of the particle come directly from Newtonssecond law of motiondVpF = mp(1)dtwhere F is the resultant force vector

41、on the particle, Vp is the particle velocity vector, and mp isthe particle mass.The major component of the force acting on a particle is the drag that is exerted on the particleby the fluid. The drag force, FD , takes the formF =(V -V )（2）Dpf8In Eq. (2), V f represents the local fluid velocity vecto

42、r, d p is the particle diameter, and r p isthe particle density. The drag coefficient, CD , is given by24C =(1+ 0.15 Re0 687)（3）DsResand the particle Reynolds number based on the relative（slip）velocity between the particle and thefluid, Res , is defined by(Vp -Vf )dpRes =（4）vWhere v is the kinematic

43、 viscosity of the continuous phase.There are additional forces on the particle, which can be included inthe simulation. Theseadditional forces account for large pressure gradients ( Fp ), buoyancy ( FB ), added mass ( FA ),as well as a rotating coordinates term which accounts for both centrifugal an

44、d Coriolis effects( FR ). Equations (5)-(8) give mathematical representations of these terms.Pressure gradientpd 2F = -p ÑP(5)p4Particle buoyancyp fFB = mp (1- r ) g(6)pAdded massmpr f dVpFp = -(7)2r dtpRotating coordinatesFp = -mp 2w´Vp + w´(w´ X p )(8)pd 2r Cp p DVp -VfIn the p

45、ressure gradient term given by Eq.（5）, P is the pressure in the continuous phase. Thebuoyancy force in Eq. （6）is needed when the particles and fluid have significantly differentdensities and when inclusion of gravitational effects is desired. The added mass force, Eq.（7）,accounts for the inertia of

46、the fluid surrounding the particle. In order for the particle to moverelative to the carrier fluid, some of the fluid must accelerate along with the particle. Equation（8）accounts for both centrifugal as well as Coriolis effects. This term is important when particles arebeing med in a rotating frame

47、of reference, for example, inside a pump impeller or rotatingwrepresents the angular velocity vector of the rotating coordinate system, andturbine. In Eq（. 8）,X p is the particle position relative to the center of rotation.作者：Jeremy K. Edwards; Brenton S. McLaury; Siamack A. Shirazi国籍：America出处：Jour

48、nal of Energy Resources Technology译文一弯管和盲三通中的颗粒冲蚀模型管配件表面上的侵蚀模式，现在可以通过计算流体动力学（CFD）代码技术得到。这一全面侵蚀预报过程包括：1）流场模拟的产生，2）大量的流场的内部的粒子的运动轨迹的计算，和 3）侵蚀模型方程被应用作粒子几何形状的撞击壁面。其他侵蚀有关的数量，即颗粒的沉积速率，以及本地平均冲击角和速度分量，也被在程序中。所有量（流的解决方案，粒子的运动轨迹，侵蚀配置文件）通过三维可视化工具被进行分析。目前的工作专注于两个管件常用于石油和天然气生产行业：弯道。首先，流场和侵蚀通过与实验数据的比较评估。侵蚀产量趋势和位置

49、最大的抗磨损与实验结果是一致的。接着，规定的侵蚀性条件下, 分析两个中心线的曲率与直径的比率为 1.5 和 5.0 的 90 度弯道。侵蚀结果表现在表面轮廓形式。最后，在侵蚀性条件下，侵蚀率同弯道和盲三通管道中测试案例进行对比。介绍固体颗粒侵蚀可能是石油流体的生产和中的一个主要问题。夹带的固体颗粒（如沙粒）撞击管道，阀门，管件，和其它系统组件的内表面，导致机械磨损，和最终这些设备的故障。几乎每一个流体输送系统中含有很容被固体颗粒侵蚀的杂质成分。这种现象可以是非常浪费的，需要频繁重新放置组件以及系统停机的时间。一定的几何形状比其他的更容易受到侵蚀损坏。例如，在一定条件下重定向流场的管件（如弯管和

50、三通接头）遇到严重侵蚀。这项工作的是评估肘管的性能和在侵蚀过程中三通接管。由于频繁被使用于石油和天然气生产，这些几何形引起人们特别的。夹带在产生的流体中的颗粒可以流体流线和撞击配件壁。粒子在管壁上的撞击可以去除墙体材料,使其随着时间的推移变得越来越薄，最终导致破坏。为了保持运营成本和系统停机时间在最小，有必要砂土侵蚀。侵蚀的方法之一是挑选操作条件(如流量)以限制侵蚀到可接受的水平。此外，管道材料明智的选择可以帮助侵蚀。在高度侵蚀的环境下，必须采用侵蚀的替代方法在许多情况下，三通几何被安装以适应极其侵蚀性的环境。近乎停滞的流体层中的封孔部几何体会提供了一个撞击颗粒物缓冲，从而显著着减少侵蚀破坏。

51、目前的研究项目侧重于侵蚀程序的应用，使计算流体动力学（CFD）代码具备商业价值。侵蚀程序被开发以同 CFX 使用，在 AEA 技术公司被发展，CFX 是一个包含了在这项研究中使用的拉格朗日列粒子追踪模型的三维流领域解算器。这一侵蚀程序可用于以更好地了解参数，如进气条件，流体性质，流速，颗粒大小和浓度，和几何形状，影响侵蚀的行为。背景两个有趣的几何体是弯头和插管三通，因为它们广泛应用于管道系统。在弯头，几何体弯曲管壁改变水流方向。颗粒物可以穿过流体的流线撞击配件壁。当侵蚀速率大，往往用三通取代肘管。其是，三通可以在停滞区为进入颗粒可以提供一个“缓冲”，从而减小侵蚀速率。早前，实验工作进行弯道和三

52、通上进行，例如，见 Bourgoyne ，Tolle和 Greenwood。尽管如此，目前尚不清楚在什么条件下有利于在侵蚀性环境中使用三通。此外一组给定条件下三通的最佳最佳，问题仍然没有得到解决。因此，CFD实验正在进行以帮助确认在这些复杂的几何体中影响侵蚀的重要参数。感的是，如何能够准确地几何体的大范围侵蚀行为和侵蚀条件。一些简单的侵蚀模型适用于一些配件，如肘管和三通。例如，Shirazi 等人和 Sa开发的简单的模型来肘管的侵蚀。在另一项研究中，Wang 等人使用建模和粒子追踪研究弯头弯曲在侵蚀速率上的影响。几乎所有目前可行的模型只视侵蚀为直接冲击造成的结果；水流波动对弯头侵蚀的影响不被考

53、虑。我们可以区分颗粒流体之前相互作用和颗粒碰壁影响的研究为两种，一种可以区辨两类颗粒冲击如图 1 所绘。这两类是:1)直接冲击机制 2)随即冲击机制。如果侵蚀主要是由于直接冲击机制，那么这表明颗粒由于平均流速影响被主要趋势影响趋往壁面。当颗粒相对于载带流体规模大和密度高时，或粘性效果较差的环境下，直接冲击能够占据主导地位，就如砂在空气中的情况。随机冲击是当流速由于乱流影响颗粒波动并冲撞时撞击机制的。而在直管发生的粒子冲撞是由于这随机撞击机制。在个直管中，即使没有在径向方向上，指示没有平均流度引导颗粒朝向管壁，颗粒仍旧撞击，因为它们受到涌动漩涡的影响。这些漩涡可以传送径向动势到附近的管壁上的微粒

54、，造成随机冲击。图 2了研究中弯管和盲三通的几何形状和命名法则。图中 D 直径的弯头内外的半径被分别表示为 r1 和 r2，两壁中心线的半径表示为 r。为了表示流场的结果，上游或下游其一从内壁到中心线被表示为量 h，上游或下游其一内外壁间距被表示为量 x。三通的几何形状也如图 2 所示，配管直径分别为 D1，D2，和 D3。在这项研究中，这三个三通几何形的管道直径大小相等。图 1直接和随机冲击理论图 2 弯管和盲三通名法则型号说明广义颗粒侵蚀包括三个模拟：1）流程建模，2）大量的砂颗粒模拟，3）应用经验侵蚀方程。CFX 包含有关流体运动和粒子的运动方程的方程的能力。这种能力由于其所使用的粒子浓

55、度太低已经不在工作中被使用了。模型需包含以下一些必要的信息来执行所有的后续计算：速度分量,变动数量，湍能和耗散率，还有载体的密度和粘度流体性质都包含在流场模拟。一旦使用 CFD 编码获得了模拟模型的字段，那么解决方案就是在一个几何图形的处以大量的砂颗粒集结。一个大型的砂颗粒模型，为了获得一个合理的分配并且减少减少在侵蚀中的散播，几千颗粒通常是需要的。每个粒子是分别按照流场和粒子冲击信息跟踪到的。当粒子撞击墙壁的时候，速度和位置都会开始集结，一组经验侵蚀方程就可以用于研究了。这些关系是用来确定从那些冲所产生的质量损失。这些流失方程解释了相关的冲击的速度和角度,以及颗粒形状和墙体材料的机械性能。为

56、了以一个更方便的方式进行可视化侵蚀,侵蚀数据转移到后处理程序。这个所谓的后处理程序可以用于生成等高线侵蚀数量。这不仅了模型、粒子轨迹、侵蚀的同步检查,而且还提供了能够识别高侵蚀领域的能力。模型模型是通过使用一个计算流体动力学(CFD)的代码。该代码用于这项工作是采用 CFX,由 AEA 技术公司。采用 CFX 利用有限体积、多嵌段的来解决方程的数值的流体运动在一个用户定义的计算网格。阿肯色州教育技术和 Patankar 描述程序,用于解决这个方程的流体运动。过程流体解决方案包含首先生成计算网格。一个预处理程序是可在软件,用于执行该任务。其次,解决方案选项,例如进口和边界条件,湍流模型和离散化方案,被指定。最后一步是运行流场求解生成实际的流场模拟。它包含几个模型对湍流的行为。各向同性和各向非同性湍流模型是可用的。此外,大量的离散化方案可以获得最精确的流量可能的解决方法。爱德华兹等人地址选择湍流模型和离散化方案对于二维和三维及其效果的准确性流场的解决方案。对于这个工作,一个微分雷诺应力湍流模型和二次逆风离散化方案被使用,除非另有规定。二次逆风离散化方案是第三订购条