Computational Analysis of Flow Characteristics of Iron Ore Slurry in Pipeline and Bend

Abstract

Particulate transport in the form of slurry using pipeline system is continuously gaining popularity as it is economic, ensures real time inventory management, environment friendly and reliable at user’s end. To design the pipelines and its associated facilities designers need accurate information regarding pressure drop, critical velocity, flow regimes, hold up etc. Multi-phase flows are complex and the correlations presently available in open literatures for the above mentioned parameters have a prediction error 25-35%. This much of error in design and slurry operation has serious cost implication and is totally unacceptable. In the present study, an attempt has been made to simulate the mineral (iron ore) slurry flow through horizontal straight pipe and 900 pipe bend for prediction of head loss characteristics. To simulate the slurry flow commercial CFD software FLUENT 15 has been used. An Eulerian model based on kinetic theory of granular flow is used to represent multiphase phenomenon. To describe the turbulence present in the flow RNG k-ɛ turbulent model coupled with standard wall treatment with mixture properties had been employed. The Simulation is performed on pipeline having 50 mm diameter for both straight pipe and elbow. The solid concentration was varied from 20-60% (by weight) with flow velocity range of 2-5 m/s having mean particle size of iron to be 59 μm. The effect of particle size was also studied by varying the particle size range from less than 53, 53-75 and 75-106 μm. Before performing simulation on iron-ore slurry, the simulated results are validated with the experimental data taken from the open literature. The simulated data predicted the relative pressure drop showed fair agreement with the experimental results. The pressure drop increases non-linearly with solid concentration, velocity and particle size for straight pipe and elbow. Increase in solid concentration and velocity results in deposition of solid particles at the lower periphery of straight pipe. The higher solid concentration zone for elbow was at extrados of pipe due to the effect of centrifugal force on solid particles. The variation in radius-to-diameter ratio of elbow resulted in change in floe characteristics. The pressure drop was minimum at r/D 2.5. The disturbance in velocity profiles and concentration profiles was maximum for lower r/D ratio due to sudden change in direction of flow.