Flow Behavior of Plastic Particles in the Lower Part of Blast Furnace

Abstract

Injection of plastics into blast furnaces as an alternative reducing agent has been carried out for the purpose of mitigation of carbon dioxide emissions. Several studies on the pyrolysis of plastic particles have been reported, however flow behavior of plastic particles or unburnt char in actual blast furnace is not clear.In this study, hotmodel experiments and thermogravimetry analysis were conducted for the modeling of gasification and combustion behavior of plastic particles, then flow behavior of plastic particle and unburnt char in a blast furnace was calculated by numerical simulation. According to the observation results of combustion experiment, volatile matter of plastics seems to be evolved at the surface of the particles. Regarding reaction of char derived from plastics, thermogravimetry analysis showed that rate of gasification of unburnt char depended on the rate of heating. Gasification rate in the case of rapid heating condition tended to increase.As the results of numerical simulations, initial diameter of plastics and char diameter determined the flow behavior in the blast furnace. When relatively small plastic was injected or diameter of unburnt char was small, unburnt char went upward along with gas flow and most of it might be consumed at the cohesive zone. On the other hand, when relatively coarse plastics was injected and diameter of unburnt char was relatively coarse, it was suggested that unburnt char accumulated around the deadman.Therefore, it is considered that fine plastics injection is desirable for the stable operation of blast furnace.

Coupled Typical Coke Gasification and Sintering Ore Reduction in CO–N2–H2

“…Therefore, some researchers have proposed a hydrogen metallurgy process represented by blast furnace hydrogen-rich smelting technology, including blast furnace injection of coke oven gas, 1−4 coal manufacturing gas, and natural gas, 5,6 or other hydrogen-containing substances. 7,8 After the blast furnace is rich in hydrogen, the deterioration of coke in the blast furnace is mainly caused by the dissolution reaction. There are two different cases of coke dissolution reaction: one is the carbon dissolution reaction between coke and CO 2 , and the other is the water-gas reaction between coke and H 2 O.…”

“…Hydrogen, as a reducing agent, causes no pollution and is an ideal substitute for carbon. Therefore, some researchers have proposed a hydrogen metallurgy process represented by blast furnace hydrogen-rich smelting technology, including blast furnace injection of coke oven gas, − coal manufacturing gas, and natural gas, , or other hydrogen-containing substances. , …”

Blast furnace injection for minimizing the coke rate and CO2emissions

“…Furthermore, the obtained result depends on the original coke reactivity and strength [46]. Another study revealed that char placed in coke pores can block the gas diffusion there and hinder in such a way the coke conversion [47]. A study on anthracite showed that CO 2 preferentially reacts with char, adhered to the coke surface, making SiC easier to form and wet the slag, which can enter pores and passivate gas from entering.…”

Conversion of injected waste plastics in blast furnace

“…14 Recently, it was reported that coarse particles move along with gas flow, and fine plastic injection is desirable for stable BF operation. 15 This study focuses on the reaction kinetics of the WP under raceway, bird's nest and shaft conditions. A wide range of analytical, laboratory and pilot facilities was applied to gain knowledge on separate stages of WP conversion, its injection behaviour, solution loss reaction and interaction with coke.…”