A comparison of analytical and numerical models with experimental data for gas-solid flow through a straight pipe at different inclinations

A model was developed for the flow of gas-solid suspensions through an inclined pipe. The model predicts the ratio of the total pressure drop in the inclined pipe to that of a horizontal pipe. The model also predicts the critical pipe angle, which is defined as the angle at which the maximum pressure drop for a given solids flow rate is achieved. The model is based on the continuum theory for describing the mass and momentum balance equations for the fluid and solid phases. Numerical simulations confirmed that the critical pipe angle for the gas-solid flow is lower than 90°.