Mechanical Analyses on Stability of Particle Flows Near Raceway of Blast Furnace

Abstract

Stability of particle flows near raceway in blast furnace has been mechanically analyzed using model experiments and simulations using Discrete Element Method (DEM). Results obtained are as follows.
(1) Unstable raceway shows that particles above raceway near wall periodically hang and slip.
(2) Unstable raceway has long periodical changes about several seconds in addition to short periodical change about several 10 ms that stable raceway exhibits.
(3) Unstable raceway shows the ratio of the height to the depth is greater than about 1 on the average.
(4) Excess enlargement of tuyere diameter or blast volume could lead to unstable raceway.
(5) Although increase of input energy from gas into bed raises efficiency of energy transfer from gas to particles, the efficiency is independent on raceway stability.
(6) With the objective raceway stability and decreasing generation of fine coke in the raceway, there is appropriate range of conditions in the input gas energy.