A Procedure to Predict Solid Particle Erosion in Elbows and Tees

Abstract

A semi-empirical procedure has been developed for predicting erosion rates in pipe geometries, such as elbows and tees. The procedure can be used to estimate safe operating conditions and velocities in oil and gas production where sand is present. In the proposed procedure, a concept is introduced that allows determination of erosion rate for different pipe geometries. In the procedure, based on empirical observations, the erosion rate is related to the impact velocity of sand particles on a pipe fitting wall. A simplified particle tracking model is developed and is used to estimate the impact velocity of sand particles moving in a stagnation region near the pipe wall. A new concept of equivalent stagnation length allows the simplified procedure to be applicable to actual pipe geometries. The “equivalent stagnation regions” of an elbow and a tee geometry of different sizes are obtained from experimental data for small pipe diameters, and a computational model is used to extend the procedure to larger pipe diameters. Currently, the prediction method applies to mild steel and accounts for the effects of sand size, shape, and density; fluid density, viscosity, and flow speed; and pipe size and shape. The proposed method has been verified for gas and liquid flows through several comparisons with experimental data reported in the literature. The results of the model accurately predict the effects of sand size and fluid viscosity observed in the experiments. Furthermore, predicted erosion rates showed good agreement with experimental data for gas, liquid, and gas-liquid flows in several 50.8-mm (2-in.) elbows and tees.

Solid-particle erosion in the tube end of the tube sheet of a shell-and-tube heat exchanger

“…The results also indicate that the erosion rate is a function of the angle of impact. Prediction of erosion in straight pipes, elbows and tees show the strong in uence of uid properties, sand size and ow velocity on the rate of erosion [17,18,33,39]. There have been many attempts in the past to represent the solid particle erosion process by an analytical formula that could be used to predict erosion under any condition.…”

“…The mass loss for all solid particle impingements was compiled to generate the local penetration rate for each boundary cell. At any given boundary cell, the local penetration rate, P n , was calculated using the following equation [15,17]:…”

“…McLaury et al [8] extended the mechanistic model that was developed earlier for predicting erosion in standard elbows [17,18] to predict erosion in long-radius elbows. In that work, they accounted for the elbow radius of curvature and for the e ect of turbulent uctuations of the 887 ow.…”

Erosion and penetration rates of a pipe protruded in a sudden contraction

“…Particle impingement information (impact angle and impingement velocity) is fed into this erosion equation to calculate local and total erosion rate (mg of material removed/g of particle throughput). An additional equation provided by Shirazi et al [29] which gives an additional measurement of erosion, termed as Penetration Rate (mm/y) was used.…”

“…This model is provided in the following formulae: [29] was used to calculate the penetration rate which is the depth of the eroded material/year of time period as follows:…”