Research On The Erosion Mechanism Of Cyclone Separator's Wall Caused By Gas-Solid Two-Phase Flow

Cyclone separator has obvious advantages of simple structure, high temperature resistant, high pressure resistant and convenient maintenance. These make cyclone separator share a wide range of applications in many industries. However, some problems have revealed in the actual operation, especially the erosion of cyclone separator's surface wall, which seriously restricts the cyclone's development and application. At present, previous researches don't have an adequate understanding of the wall erosion mechanism of cyclone separator. Most of existing conclusions are obtained from field experience rather than systemic theoretical analysis. In this paper, theoretical analysis and numerical simulation were adopted to study the serious erosion problem of cyclone separator. The advanced computational fluid dynamics was applied to investigate wall erosion of cyclone separator caused by gas-solid two-phase flow and discuss the erosion mechanism further.Firstly, the theories of CFD-based erosion prediction model were introduced in this paper. Usually this model consists of three main sections: internal flow field modeling, particle trajectory tracking, and erosion computing modeling. On this basis, using this method compute the erosion of cyclone separator's surface wall caused by gas-solid two-phase flow. Through calculation find that the eroded surface wall of cyclone separator is mainly local erosion. Several severe erosion regions are the annular space near the roof, the cyclone barrel which is in the direct line-of-sight of the inlet, the helical-shaped grooves in separated barrel space and the lower cone. Erosion rate of annular space increases first and then decreases along circumferential direction. At separated barrel space, the trend of erosion rate distribution along the axial direction is"wave"shape; there are clear sharp crests and troughs appearance. At separated cone space, erosion increases rather strongly with axial distance down the cone section and reaches its maximum value in the lower or lowermost section of the cone and then lower apparently.Secondly, in this paper the erosion law of cyclone separator's surface wall was studied under different structure parameters (vortex finder diameter ratio, dust exit diameter ratio, and inlet area ratio), different inlet structure, different operation parameters (inlet velocity and operation temperature) and different particle diameter. The results show that these parameters have varying degrees influence on the erosion location and erosion rate of cyclone separator's wall.Finally, based on the laboratory and industrial field application of cyclone separator, observe macro and micro morphology of local wear parts wall, study its failure analysis and establish wall erosion model. At the same time, the erosion mechanisms of different parts of cyclone separator and micro mechanisms of severe local erosion zone caused by particles impingent are also studied in this section. Research results show that the failure of cyclone separator's wall is not the uniform erosion of surface wall, but the local erosion caused by particles seriously impact. The local eroded regions have obviously plastic deformation and appear plough troughs. Grinding strips are uniform on the surface wall, grinding mark cardinally identical direction. There are pits appear accompanied with the local eroded regions. Plastic deformation and extrusion is observed at the tip of the leading edge of the large trough. In terms of gas-solid two-phase flow characteristics, there are three main mechanisms: the directional impingement of solid particles, the random impingement of particles in turbulent motion, and the friction of a sliding bed pressing onto the wall. The micro mechanism of local erosion on surface wall of cyclone separator's is scousr-cutting-impingement-scousr-exfoliation. That is to say, micro-cutting arises primarily from the small collision angle of particle and surface, while collision exfoliation arises from the bigger collision angle.