催化劑氫氣提升管沖蝕磨損數(shù)值研究b外文翻譯

1、外文翻譯畢業(yè)設(shè)計題目： 催化劑氫氣提升管沖蝕磨損數(shù)值研究 原文 1：Ming solid particle erosion in elbows andplugged tees譯文 1：彎管和盲三通中的的顆粒沖蝕模型原文 2：The impact angle dependence of erosion damagecaused by solid particle impact譯文 2：固體顆粒侵蝕造成的沖擊損傷影響的角度依賴性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國籍：America出處：Jour

48、nal of Energy Resources Technology譯文一彎管和盲三通中的顆粒沖蝕模型管配件表面上的侵蝕模式，現(xiàn)在可以通過計算流體動力學（CFD）代碼技術(shù)得到。這一全面侵蝕預(yù)報過程包括：1）流場模擬的產(chǎn)生，2）大量的流場的內(nèi)部的粒子的運動軌跡的計算，和 3）侵蝕模型方程被應(yīng)用作粒子幾何形狀的撞擊壁面。其他侵蝕有關(guān)的數(shù)量，即顆粒的沉積速率，以及本地平均沖擊角和速度分量，也被在程序中。所有量（流的解決方案，粒子的運動軌跡，侵蝕配置文件）通過三維可視化工具被進行分析。目前的工作專注于兩個管件常用于石油和天然氣生產(chǎn)行業(yè)：彎道。首先，流場和侵蝕通過與實驗數(shù)據(jù)的比較評估。侵蝕產(chǎn)量趨勢和位置

49、最大的抗磨損與實驗結(jié)果是一致的。接著，規(guī)定的侵蝕性條件下, 分析兩個中心線的曲率與直徑的比率為 1.5 和 5.0 的 90 度彎道。侵蝕結(jié)果表現(xiàn)在表面輪廓形式。最后，在侵蝕性條件下，侵蝕率同彎道和盲三通管道中測試案例進行對比。介紹固體顆粒侵蝕可能是石油流體的生產(chǎn)和中的一個主要問題。夾帶的固體顆粒（如沙粒）撞擊管道，閥門，管件，和其它系統(tǒng)組件的內(nèi)表面，導(dǎo)致機械磨損，和最終這些設(shè)備的故障。幾乎每一個流體輸送系統(tǒng)中含有很容被固體顆粒侵蝕的雜質(zhì)成分。這種現(xiàn)象可以是非常浪費的，需要頻繁重新放置組件以及系統(tǒng)停機的時間。一定的幾何形狀比其他的更容易受到侵蝕損壞。例如，在一定條件下重定向流場的管件（如彎管和

50、三通接頭）遇到嚴重侵蝕。這項工作的是評估肘管的性能和在侵蝕過程中三通接管。由于頻繁被使用于石油和天然氣生產(chǎn)，這些幾何形引起人們特別的。夾帶在產(chǎn)生的流體中的顆?？梢粤黧w流線和撞擊配件壁。粒子在管壁上的撞擊可以去除墻體材料,使其隨著時間的推移變得越來越薄，最終導(dǎo)致破壞。為了保持運營成本和系統(tǒng)停機時間在最小，有必要砂土侵蝕。侵蝕的方法之一是挑選操作條件(如流量)以限制侵蝕到可接受的水平。此外，管道材料明智的選擇可以幫助侵蝕。在高度侵蝕的環(huán)境下，必須采用侵蝕的替代方法在許多情況下，三通幾何被安裝以適應(yīng)極其侵蝕性的環(huán)境。近乎停滯的流體層中的封孔部幾何體會提供了一個撞擊顆粒物緩沖，從而顯著著減少侵蝕破壞。

51、目前的研究項目側(cè)重于侵蝕程序的應(yīng)用，使計算流體動力學（CFD）代碼具備商業(yè)價值。侵蝕程序被開發(fā)以同 CFX 使用，在 AEA 技術(shù)公司被發(fā)展，CFX 是一個包含了在這項研究中使用的拉格朗日列粒子追蹤模型的三維流領(lǐng)域解算器。這一侵蝕程序可用于以更好地了解參數(shù)，如進氣條件，流體性質(zhì)，流速，顆粒大小和濃度，和幾何形狀，影響侵蝕的行為。背景兩個有趣的幾何體是彎頭和插管三通，因為它們廣泛應(yīng)用于管道系統(tǒng)。在彎頭，幾何體彎曲管壁改變水流方向。顆粒物可以穿過流體的流線撞擊配件壁。當侵蝕速率大，往往用三通取代肘管。其是，三通可以在停滯區(qū)為進入顆?？梢蕴峁┮粋€“緩沖”，從而減小侵蝕速率。早前，實驗工作進行彎道和三

52、通上進行，例如，見 Bourgoyne ，Tolle和 Greenwood。盡管如此，目前尚不清楚在什么條件下有利于在侵蝕性環(huán)境中使用三通。此外一組給定條件下三通的最佳最佳，問題仍然沒有得到解決。因此，CFD實驗正在進行以幫助確認在這些復(fù)雜的幾何體中影響侵蝕的重要參數(shù)。感的是，如何能夠準確地幾何體的大范圍侵蝕行為和侵蝕條件。一些簡單的侵蝕模型適用于一些配件，如肘管和三通。例如，Shirazi 等人和 Sa開發(fā)的簡單的模型來肘管的侵蝕。在另一項研究中，Wang 等人使用建模和粒子追蹤研究彎頭彎曲在侵蝕速率上的影響。幾乎所有目前可行的模型只視侵蝕為直接沖擊造成的結(jié)果；水流波動對彎頭侵蝕的影響不被考

53、慮。我們可以區(qū)分顆粒流體之前相互作用和顆粒碰壁影響的研究為兩種，一種可以區(qū)辨兩類顆粒沖擊如圖 1 所繪。這兩類是:1)直接沖擊機制 2)隨即沖擊機制。如果侵蝕主要是由于直接沖擊機制，那么這表明顆粒由于平均流速影響被主要趨勢影響趨往壁面。當顆粒相對于載帶流體規(guī)模大和密度高時，或粘性效果較差的環(huán)境下，直接沖擊能夠占據(jù)主導(dǎo)地位，就如砂在空氣中的情況。隨機沖擊是當流速由于亂流影響顆粒波動并沖撞時撞擊機制的。而在直管發(fā)生的粒子沖撞是由于這隨機撞擊機制。在個直管中，即使沒有在徑向方向上，指示沒有平均流度引導(dǎo)顆粒朝向管壁，顆粒仍舊撞擊，因為它們受到涌動漩渦的影響。這些漩渦可以傳送徑向動勢到附近的管壁上的微粒

54、，造成隨機沖擊。圖 2了研究中彎管和盲三通的幾何形狀和命名法則。圖中 D 直徑的彎頭內(nèi)外的半徑被分別表示為 r1 和 r2，兩壁中心線的半徑表示為 r。為了表示流場的結(jié)果，上游或下游其一從內(nèi)壁到中心線被表示為量 h，上游或下游其一內(nèi)外壁間距被表示為量 x。三通的幾何形狀也如圖 2 所示，配管直徑分別為 D1，D2，和 D3。在這項研究中，這三個三通幾何形的管道直徑大小相等。圖 1直接和隨機沖擊理論圖 2 彎管和盲三通名法則型號說明廣義顆粒侵蝕包括三個模擬：1）流程建模，2）大量的砂顆粒模擬，3）應(yīng)用經(jīng)驗侵蝕方程。CFX 包含有關(guān)流體運動和粒子的運動方程的方程的能力。這種能力由于其所使用的粒子濃

55、度太低已經(jīng)不在工作中被使用了。模型需包含以下一些必要的信息來執(zhí)行所有的后續(xù)計算：速度分量,變動數(shù)量，湍能和耗散率，還有載體的密度和粘度流體性質(zhì)都包含在流場模擬。一旦使用 CFD 編碼獲得了模擬模型的字段，那么解決方案就是在一個幾何圖形的處以大量的砂顆粒集結(jié)。一個大型的砂顆粒模型，為了獲得一個合理的分配并且減少減少在侵蝕中的散播，幾千顆粒通常是需要的。每個粒子是分別按照流場和粒子沖擊信息跟蹤到的。當粒子撞擊墻壁的時候，速度和位置都會開始集結(jié)，一組經(jīng)驗侵蝕方程就可以用于研究了。這些關(guān)系是用來確定從那些沖所產(chǎn)生的質(zhì)量損失。這些流失方程解釋了相關(guān)的沖擊的速度和角度,以及顆粒形狀和墻體材料的機械性能。為

56、了以一個更方便的方式進行可視化侵蝕,侵蝕數(shù)據(jù)轉(zhuǎn)移到后處理程序。這個所謂的后處理程序可以用于生成等高線侵蝕數(shù)量。這不僅了模型、粒子軌跡、侵蝕的同步檢查,而且還提供了能夠識別高侵蝕領(lǐng)域的能力。模型模型是通過使用一個計算流體動力學(CFD)的代碼。該代碼用于這項工作是采用 CFX,由 AEA 技術(shù)公司。采用 CFX 利用有限體積、多嵌段的來解決方程的數(shù)值的流體運動在一個用戶定義的計算網(wǎng)格。阿肯色州教育技術(shù)和 Patankar 描述程序,用于解決這個方程的流體運動。過程流體解決方案包含首先生成計算網(wǎng)格。一個預(yù)處理程序是可在軟件,用于執(zhí)行該任務(wù)。其次,解決方案選項,例如進口和邊界條件,湍流模型和離散化方案,被指定。最后一步是運行流場求解生成實際的流場模擬。它包含幾個模型對湍流的行為。各向同性和各向非同性湍流模型是可用的。此外,大量的離散化方案可以獲得最精確的流量可能的解決方法。愛德華茲等人地址選擇湍流模型和離散化方案對于二維和三維及其效果的準確性流場的解決方案。對于這個工作,一個微分雷諾應(yīng)力湍流模型和二次逆風離散化方案被使用,除非另有規(guī)定。二次逆風離散化方案是第三訂購條