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![Figure 1. Erosion damage in a standard elbow [2].](profile/Ali-Farokhi-3/publication/327109573/figure/fig16/AS:722560161427456@1549283175115/Erosion-damage-in-a-standard-elbow-2_Q320.jpg)
In gas and oil industry, erosion damage to pipelines' bends and elbows due to the presence of sand particles has been a challenging issue. In this study, a computational model approach was used to evaluate the erosion rates at different vertical return bends: Sharp bend, standard elbow, 180° pipe bend, and long elbow. The airow in the pipe was simu...
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... study mesh independency, four diierent meshes for standard elbow as listed in Table 3 are used in the simulations. According to Figure 5, the mesh with 2,640 grids on the cross-section is suitable for simulations. The nal cross-section mesh and butterry grid in 3D pipes used in all cases are depicted in Figures 4(b) and 6. ...
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... study mesh independency, four diierent meshes for standard elbow as listed in Table 3 are used in the simulations. According to Figure 5, the mesh with 2,640 grids on the cross-section is suitable for simulations. The enal cross-section mesh and butterry grid in 3D pipes used in all cases are depicted in Figures 4(b) and 6. ...
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is coming from natural gas sources. Apart from endangered the environment, carbon dioxide also affects the caloric
value of the natural gas itself. The presence of carbon dioxide as contaminants is a nuisance for oil and gas industry
as...
Citations
... The equations of continuity, momentum, and energy are as follows [5,11,40]: ...
Steam turbines play a critical role in power generation systems. Therefore, increasing the efficiency of steam turbines is highly desirable, especially in LP stages. One of the suggested techniques to reduce wetness losses in LP stages is the hot steam injection. In the first section of the present study, the effect of 3D turbine blade span length on wet steam flow parameters is investigated. Then, the performance of various arrangements of hot steam injection holes (single slot, in-line no. 1, in-line no. 2, staggered no. 1, and staggered no. 2) is evaluated and compared. The results demonstrated that the in-line no. 1 arrangement is the best design for hot steam injection. In this arrangement, the wetness and condensation loss are reduced by 79% and 44%, respectively, and the kinetic energy loss is less than the other arrangements. However, the kinetic energy is still about 28% lower than in the no-injection case. Ultimately, excessive kinetic energy reduction due to hot steam injection is prevented by decreasing the injection pressure. As the injection pressure is reduced from 160 to 100 kPa, the kinetic energy, wetness, and condensation loss are reduced by 9%, 40%, and 17%, respectively, compared to the no-injection case.
... Erosion and wear occur in pipes, valves, elbows, and cyclones' bodies. The particle wear results from particulate impact with the walls [19][20][21]. Jafari et al. [15] studied the influence of surface roughness on erosion. Farokhipour et al. [22] and Duarte et al. [23] examined the impact of oneway, two-way, and four-way couplings on the erosion rate in plugged tees and bends using CFD tools. ...
In this study, the effect of roughness of cyclone wall on the rate of erosion and cyclone performance was studied using the CFD technique with the aid of the Ansys-Fluent 19.2 software. The Reynolds stress transport model was used to simulate the airflow turbulence in the rotating flows in the cyclone. The validated computational model was used, and the variations of axial velocity, tangential velocity, collection efficiency, cyclone pressure drop, and rate of erosion for different wall roughness were evaluated. For simulating surface erosion, the Oka model was used. The result of this study revealed that the wall roughness significantly affected airflow behavior in the cyclone and the resulting cyclone performance. In addition, when the wall roughness increased, the wear rate decreased. It was also found that the solid loading and inlet gas velocity significantly affect the erosion rate and even more than that of particle size.
... However, most of these studies are gas-dominated flows. For liquid-dominated cases, there are only a few experimental data on liquid-solid or slurry erosion reported in the literature [5][6][7][8][9] and for elbows in series, more attention has been drawn in recent years [10][11][12][13][14]. ...
Erosion of elbows in series has received more attention recently as many facilities have elbows in series with various orientations and installations. It has been observed from experiments that, for liquid-dominated flows when two elbows are placed in series and with a small distance between them, the maximum erosion takes place in the second elbow. However, it is also necessary to study the effect of the orientation of the elbows because in the oil and gas industry, for example, there are all types of combinations of elbows in series in the field. In this work, experiments were conducted in a 50.8 mm diameter experimental facility considering liquid-solid and liquid-gas-solid flows and one configuration of elbows in series: where the first elbow for both configurations is upward vertical-horizontal and the second elbow orientation is horizontal-vertical downward. Also, the distance between elbows was kept constant (being three diameters). Additionally, Computational Fluid Dynamics (CFD) studies were performed and compared with experiments. After validation and sensitivity studies concerning numerical solutions, a comprehensive numerical study was conducted, taking into account different scenarios regarding the orientation of elbows using three configurations of two elbows in series. The results show that the normal and the 180° configuration of two elbows in series are less sensitive to the gravity orientation for liquid-solid flows than the other two configurations investigated. On the other hand, for liquid-gas-solid flows, erosion changes with gravity orientation. The worst-case scenario for liquid-solid flow is suggested to be the 180° configuration, while for the liquid-gas-solid flow, the 90° configuration. Thus, it is important to understand the erosion behavior with the orientation of the elbows, because erosion can be reduced by changing the orientation or the configuration of elbows in series.
... The comparison of erosion rates for return bends was reported by Farokhipour et al. [27] using a computational approach. Their results showed that, among the studied configurations, the 180° J o u r n a l P r e -p r o o f Journal Pre-proof bend experiences the lowest erosion while the sharp return bend has the highest erosion. ...
... Despite the huge amount of investigations examining various aspects of erosion phenomenon in different geometries, little attention has been paid to study the interaction of solid particles at high concentrations. In summary, most of investigators used one-way or two-way coupling models for the interaction between phases [27,[30][31][32]. Farokhipour et al. [33] simulated the erosion rates for plugged tees and standard elbows. ...
Sand erosion occurs in a host of industrial applications and accounts for one of the key factors in equipment failure. This study investigated sand particle erosion performance of different 90-degree fittings. To this end, a CFD-DEM model was employed and the erosion rates of various fittings carrying particle-laden flows were analyzed. Several cases with different mass loadings were simulated using different coupling models and the erosion-related parameters including erosion rate, particle impact angle, impact velocity and frequency were evaluated. The simulation results at high mass loading showed that the four-way coupling predicts much higher erosion along the bend in the elbows compared with one- and two-way coupling models. In sharp bends and plugged tees, however, the four-way coupling model predicts the lowest erosion due to the cushioning effects generated by the incoming high speed particle collisions with the high concentration of low speed particles near the walls. Therefore, at high and moderate mass loadings the four-way coupling model must be used. Furthermore, it was determined that the plugged tee is the most erosion-resistant bend geometry, due to the cushioning effect and low frequency of particle impingements on the end region.
... They found that, for cases with high velocity of carrier fluid, the plugged tees had better performance than elbows for fine particles while, for the large particles, the recirculating region in the plugged section did not affect the particle velocity and resulted in higher erosion rates compared with the standard elbow. Using an Eulerian-Lagrangian approach, Farokhipour et al. [24] evaluated the erosion rates in different vertical return bends including a sharp bend, a standard elbow, a 180°pipe bend and a long-radius elbow. Their results showed that the sharp bends experienced the highest erosion rates, while the 180°bends had the lowest erosion among the bend configurations studied. ...
In many industrial applications, sand erosion wear is the main cause of equipment failure, particularly in the transferring pipeline fittings. In order to reduce the adverse consequences of erosion in bends, in this study the potential usage of plugged tees instead of standard elbows under a wide range of flow conditions is examined. A computational fluid dynamics (CFD) model coupled with discrete element method (DEM) was used and the particle-laden flows with different fluid velocities in the corresponding geometries carrying various entrained particle mass loadings were simulated. The reliability of selected turbulence models as well as rebound and erosion models were verified by comparing the model predictions with the available experimental data. The final simulation model included the E/CRC erosion model, and the Grant and Tabakoff rebound model. The DEM used in the computational model includes the effects of particles rotation and collisions between the particles. The study also considered the effect of modifications of the plugged length of the tee geometries. The simulation results indicated that, as the particle mass loading increases, the effectiveness of plugged tee compared to the standard elbow increases. Moreover, although increasing the plugged length will generally reduce the erosion rate due to the cushioning effect, the rate of reduction depends on mass loading.
Erosion of particles in elbows mounted in series is a detriment in the course of natural gas transmission. The flow and erosion characteristics of π-shaped pipelines were investigated via coupling the computational fluid dynamics (CFD) and the discrete phase model (DPM) method. The effect of pipe orientation on particle erosion was mainly studied. Spiral and asymmetrical trajectories of particles were observed from the second elbow to the downstream straight pipe of the fourth elbow in the non-coplanar π-shaped pipelines. The integral erosion rate of the first elbow increased by 0.35%, and it grew by 72.49% and 87.48% in the second and fourth elbows in non-coplanar structures, respectively, while the integral erosion rate of the third elbow reduced by 32.94%. In the actual transportation of natural gas, it is necessary to make local thickening treatment of the second and fourth elbow of the non-coplanar π-shaped pipelines.
In the oil and gas industry, sand particle erosion damage to elbows is a common problem. The ability to predict erosion patterns is of great importance for sizing lines, analyzing failures, and limiting production rates. Computational fluid dynamics (CFD) can be utilized to study the erosion behavior and mitigate the erosion problem for safety purposes and greater equipment longevity. In order to alleviate the adverse results of sand erosion in elbows, the current study investigated the potential of the geometrically induced swirl flow generated from flow passing through a four-lobed twisted pipe upstream of an elbow. To this end, first, the airflow in a standard elbow equipped with different swirl pipes was simulated using the SIMPLE method, then an Eulerian-Lagrangian approach was employed to track the particles, and finally, the erosion rate was computed. The simulation results indicated that the elbow’s maximum erosion rate with twisted pipes placed upstream of the elbow is lower than the one obtained for the standard pipe. In addition, as the twisted pipe position gets closer to the bend, the erosion rate further reduces. Thus, swirling flows provide a promising prospect as a mechanism to control the erosion rate in elbows.
This contribution presents a numerical analysis based on the effects of aerodynamics of the bump-based humpback whale fins available on the turbine blade edge. In this research, performance comparisons have been made based on dual sequestered blades. One of the blades was sinusoidal in shaped with Bumped Lead Edge (BLE) and the other one with Upright Leading Edge (ULE). However, all the blades are based on a similar cross-sectional profile i.e. NACA-012. This research has been based on simulations of Reynold’s number i.e. 1.8.105 of Attack Angle (AA) i.e. from ‘0º - 30º’. At this angle, especially greater than 10º, the BLE has indicated an enhancement in about 3.5% to 9.0% lift and a reducing drag whereas the negligible variation in lifts and minor drag is displayed for AA less than 10º. The findings in this result for BLE have indicated a substantial achievement in aerodynamic features for particular AA.
