Direct Injection of Biofuel in Blast Furnace Ironmaking

摘要

The feasibility of replacing pulverized coal injection in the blast furnace ironmaking process by biofuel for mitigation of greenhouse gas emission was investigated. Heat and mass balance and thermodynamic models were developed to examine the effect of biofuel injection on the behaviour of the blast furnace and of the blast furnace-cokemaking system. Four biofuels, namely eucalyptus, switchgrass, bio-oil and charcoal, were selected for the study. Injection of biofuel with high carbon and low oxygen contents is desirable to significantly reduce the CO_2 emission of the process without affecting the ironmaking ability of the furnace. Among the selected biofuels, charcoal was found most suitable for substituting coal injection. Charcoal injection is capable of reducing the GHG emission associated with Canadian blast furnace ironmaking process from 13.7 Mt/yr to 10.5 Mt/yr or 23.5%. Chemical compositions of the hot metal and slag can be controlled by adjustment of fluxing rate. Moreover, a recent inventory of Canadian biomass availability has revealed that the raw biomass demand for steel industry application of charcoal injection can be met by roadside residues produced by the forest industry.