Numerical Investigation on Effects of Deadman Structure and Powder Properties on Gas and Powder flows in Lower Part of Blast furnace

摘要

Deposition of excessive amount of fine powder in the lower part of blast furnace deteriorates permeability of packed bed for reacting gas and liquid products, and causes operation instability. Powder behavior in the lower part of blast furnace has been attracting technical and scientific interests with increase in injection rate of pulverized coal into blast furnace. This study performed numerical experiments on effects of dead-man structure and properties of generated powder on gas and powder flow behavior in the lower part of blast furnace by using two-dimensional axisymmetric mathematical model for flow and heat transfer in blast furnace based on multi-fluid theory. Among the packed bed properties, voidage has greater effect than coke diameter on penetration of high temperature gas and powder into the deadman zone and pressure drop in the furnace. The deadman having extremely low voidage is possibly to cause formation of low temperature zone in the deadman. Thus it is preferable to repress powder accumulation within deadman packed bed to keep its permeability. Increase in powder diameter raises the maximum value of volume fraction of powder within the deadman, and heavier particles tend to leave from the gas stream. Such particles are considered easy to accumulate in the deadman. Therefore decrease in generation of larger and heavier particles and increase in their consumption are effective to realize permeable deadman.