(456a) Predicting Critical Outlet Width of Hopper Systems Using Finite Element Analysis

Guidelines provided by Jenike (1961) are widely used for designing industrial scale hopper systems. One component of these guidelines is the minimum outlet width of the hopper to ensure continuous flow of the stored bulk solid. It has been experimentally observed that in most cases this critical outlet width estimate is conservative. In this work, critical outlet widths predicted by Jenike’s theory, the empirical correlation by McLean (1986), Enstad’s (1971) theory, and predictions from Finite Element Analysis (FEA) are compared. The FEA predictions use the Mohr-Coulomb elasto-plastic constitutive model provided by the ABAQUS commercial software package. Unlike Jenike’s theory and the empirical correlation, Enstad’s theory and the FEA model show that the critical outlet width depends on the material height. The effects of material parameters (internal friction angle, flow function), wall friction angle, and hopper angle on the critical outlet width predicted by the FEA are explored. In addition, comparisons to experimentally-observed critical outlet widths available in the literature are made (Eckhoff and Leversen, 1974). The primary advantage of using an FEA model for critical outlet predictions are that complex hopper systems may be simulated.

Jenike, A. W., “Gravity flow of bulk solids,” Bull. Univ. Utah, vol. 52, no. 29, 1961.

McLean, A., “Empirical critical flow factor equations.,” Bulk Solids Handl., vol. 6, pp. 779–782, 1986.

Enstad, G., “On the theory of arching in mass flow hoppers,” Chem. Eng. Sci., vol. 30, pp. 1273–1283, 1975.

Eckhoff, R. K. and Leversen, P. G., “A further contribution to the evaluation of the Jenike method for design of mass flow hoppers,” Powder Technol., vol. 10, pp. 51–58, 1974.