Pressure Loss and Hold-up Powders for Gas-Powder Two Phase Flow in Packed Beds

• Published in: ISIJ International Vol. 31; no. 5; pp. 434 - 439
• Main Authors: Shibata, Koichiro, Shimizu, Masakata, Inaba, Shin-ichi, Takahashi, Reijiro, Yagi, Jun-ichiro
• Format: Journal Article
• Language: English
• Published: The Iron and Steel Institute of Japan 1991
• Subjects: blast furnace; blockade; cold model experiment; gas-powder two phase flow; ironmaking; mathematical model; packed bed
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.31.434

Flow characteristics of gas-powder two phase flow in packed beds were experimentally examined for clarifying the aerodynamic behavior of powders in a blast furnace. It was found that two phase flow showed higher pressure loss compared with clean gas flow. Based on the experimental results, a mathematical model for gas-powder two phase flow in packed beds was developed. In this model, three kinds of interaction forces were considered, including: 1) the interaction force between gas and packed particles (Fg-b) 2) the interaction force between gas and powders (Fg-p), and 3) the restraint force of powder motion due to (i) the gravitational force of powders and (ii) the collision and the friction between powders and packed particles Fp-k. Fg-b could be given by the Ergun type gas flow resistance, and (Fg-p) could be expressed by the Stokes flow law and the Richardson-Zaki's voidage function. Finally, Fp-k could be empirically correlated by using the Fanning equation and the Froude number. This model allows satisfactory prediction of the pressure loss and the hold-up of powders in the packed bed. Furthermore, it was confirmed that the increase in the pressure loss was mainly caused by the increase in the hold-up of powders in the region of low gas velocity and by the interaction force between powders and packed particles in the region of high gas velocity.