Abstract: According to the gas solid packed bed dynamic theory， the mathematical model of the gas flow in the pellet shaft furnace (PSF) layer was established， and the boundary conditions of the mathematical model were determined. The basic law of the gas flow in PSF was studied by using the manual programming simulation， further more the influences of the structural parameters of PSF on the gas flow were discussed. The results showed that in the structural parameters， the width of the internal vertical air channels and roasting zone， the height of preheating roasting zone were the major factors that influenced the gas flow in PSF. With the increase of the width of internal vertical air channels or the height of preheating roasting zone and the decrease of the width of roasting zone， the upward cooling gas flow tended to decrease， while the downward roasting gas tended to increase. At the same time， the change of the width of internal vertical air channels or the roasting zone and the height of preheating roasting zone， also led to the change of the ratio of the roasting gas and the cooling gas， namely the change of the ratio of air volume， which was the main factor to decide the gas flow in PSF.

Key words: packed bed, pelletizing shaft furnace, gas flow, structural parameters, numerical simulation