Effect of natural gas injection point on combustion and gasification efficiency of pulverized coal under blast furnace condition

The reduction of CO₂ emission from the ironmaking process is an important issue from the view of environmental problems typified by global warming in recent years. Low RAR (reducing agent rate) operation of the blast furnace is one of effective methods for reducing CO₂ emission. Injection of HRA (hydrogenous reducing agents) from the tuyere (where is the lower part of a blast furnace) is also effective measure. In this study, the influence of HRA injection point on combustion and gasification efficiency of pulverized coal (PC) in the case of simultaneous injection of HRA and PC from double-channel lance was examined by small scale combustion furnace and three-dimensional numerical simulation for permeability in the blast furnace. Combustion experimental conditions were in three cases, case 1: injected HRA from the outer side and PC from the inner side of double-channel lance, case 2: injected HRA from inner side and PC from outer side of double-channel lance and case 3: injected HRA and PC premixed. As a result, the combustion and gasification efficiency was increased in the order of case 1, case 2 and case 3. The rate of combustion and gasification of PC was investigated in case1. Not only the oxidation reaction was also accelerated CO₂ and H₂O gasification reaction in the case of simultaneous injection HRA and PC. A three-dimensional numerical simulation of the experimental furnace was conducted, we confirmed the increase of combustion temperature, the acceleration of oxygen consumption and gasification reaction as with the experimental results in the case of simultaneous injection HRA and PC.