Experimental study on the hung-up regime in hopper–standpipe systems for Geldart-A powders

Experiments are carried out on the hung-up regime in the hopper–standpipe systems for three Geldart-A powders. Experimental results show that the hung-up regime occurs between the unstable flow regime and the slug flow regime; the incipient and terminal conditions of hung-up regime can be predicted by equations presented by Zhang [Powder Technol. 97 (1998) 109] and Steward and Davidson [Powder Technol. 1 (1967) 61], respectively.