ABSTRACT

Erosion wear occurs due to repeated impacts of solid particles and even liquid droplets with materials surfaces. The hardness of particles relative to the hardness of the target material is especially important in the mining process and petroleum industries as many types of particles with various shapes and hardness and sizes hit various pipe materials and coatings. The particle impact velocities at the pipe walls and bends are affected by the pipe geometry, fluid properties and velocity, flow patterns, particle size and distribution in the flow. The size and shape variation of particles entrained in fluids in the industry applications cause impact speed and angle variations and crater sizes on the target materials. Materials characteristics are another important, complex and fascinating part in modeling solid particle erosion. Impacting solid particles cause craters, fractures and/or cracks that eventually causes small pieces of materials to be removed. To model the erosion under multiphase flow conditions, local void fraction measurements by Wire Mesh Sensors (WMS) and Computational Fluid Dynamics (CFD) simulations of multiphase flows are being used to aid in predicting gas-liquid-sand velocities in multiphase flows. Erosion experiments and flow visualization experiments are also conducted on elbows in series in 2-inch, 3-inch and 4-inch large-scale multiphase flows. Finally, several interesting and wonderful observations that over the years have helped scientists develop and improve models for solid particle erosion are presented. Additionally, examples of various efforts that are leading to develop better models for predicting solid particle erosion are briefly discussed.

INTRODUCTION AND BACKGROUND

Solid particles entrained in fluids can impact pipelines and equipment causing wear and material removal. Particle impact velocities that are affected by the carrier fluids have the largest effect on the magnitude and distribution of solid particle erosion rates in addition to the mass of impacting particles or the particle rates. In addition to the interaction of particles with the carrier fluids, particles interaction with solid materials makes this process highly complex and produces effects that are interesting and yet important to predict for practical engineering applications. Solid particle erosion of pipelines and equipment depends on many parameters that can be categorized into three interacting components or elements: One element is solid particles themselves that vary in shape, size, hardness and density. Another important element is the materials characteristics such as hardness of materials, ductility, density, and wear characteristics. The last, and certainly not the least element, is the carrier fluid properties and complexity of the flow regimes. Interaction between these three elements is the most difficult to predict and model especially in multiphase gas-liquid-particle flows. Fluids and their interactions with solid particles add another order of magnitude in complexity for the prediction of solid particle erosion.

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