The effect of pipe length on the gravity flow of granular materials in vertical standpipes

Abstract

In an earlier publication [1], a theory of motion of particulate materials in hopperfed vertical standpipes was developed. It was used to predict the performance of a pipe in response to changes in the restriction imposed by a valve at its lower end, and to changes in the back-pressure of gas below this valve. The theoretical predictions were compared with experimental observations on a laboratory standpipe of fixed length. The present paper supplements this by presenting experimental data on the influence of standpipe length on performance, and comparing these with predictions of the theory. It is found that most of the qualitative features observed are also predicted, and that quantitative agreement between theory and observations is also encouragingly good.