The Research On The Erosion Of Liquid-Solid Two-phase Flow In The Pipelines

Pipeline plays a very important role to the development of national economy, it is widelyin various industries. In the pipeline, the erosion at the elbow is a few times higher than thestraight pipe, because when solid particle goes through the elbow, it suddenly changes thedirection of movement which is influenced by inertial and centrifugal force, so the wall isworn because of frequent collisions of particles with the pipe wall. The erosion of fluidcontaining particles to pipelines and other equipments easily lead to serious accidents, thisalways plagues the safe operation of every enterprises, especially fast velocity of flow, highhardness, large diameter of solid particles will get more serious erosion to the pipeline. Due tothe complexity of the mechanism of erosion and the bad operating conditions, so it is difficultto accurately grasp the position of erosion. We often use the method of thickening the wall orimproving materials to prevent the erosion, then it greatly increases the production costs, butthe effect is not obvious and pipeline erosion has not been effectively controlled.In this paper, we build a geometric model for pipeline systems, then use turbulencemodel, multiphase flow model and discrete phase model to simulate the erosion of threedifferent bending angles’ pipeline. We finds that particles are mainly concentrated in the outerarch wall at the elbow, at the same time, inside of the wall surface is the position which ismost likely to occur cavitation, and the secondary flow is fully developed at the elbow thatexacerbates the erosion to pipelines. After using Fluent to solve the flow field, we get discretephase particles’ movement and distribution in the pipeline, then determining the most severeabrasion area. It is found that in the90°elbow，most of the particles are concentrated in thecenter of the straight pipe with increasing axial height，and particle velocity near the wallregion is lower than the one in the center. Analyzing and comparing the different angle bend’sparticle distribution, finally we find90°bend’s comprehensive performance is the best.Contrasting and analyzing different solid particles’ characteristics and pipelineconstruction, then investigating the influence of various factors on the pipeline erosion. Theresults show that other conditions remain unchanged, erosion increases with increasing flowrate, decreases with increasing diameter and increases with increasing diameter of the discreteparticles. In addition to simulating on bends of seven different diameter ratio and getting theflow field in the pipeline. It shows that the erosion area and rate are quite different in different diameter ratio bends. when pipeline’s diameter is unchanged, the erosion gradually reduceswith the bend diameter ratio increases, but considering the cost of pipelines, the bend radiusratio is recommended4to6.The simulation results are in good agreement with theexperimental data, this is verifying the applicability of the model. It provides some referencevalue for pipeline system about abrasion failure analysis, structural optimization, locallyenhanced treatment, life prediction and risk assessment in actual production.