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

Abstract

The reduction of CO2 emission from the ironmaking process is 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 measures for reducing CO2 emission. Injection of HRA (hydrogenous reducing agents) from the tuyere (where is the lower part of 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 improvement permeability in blast furnace. Combustion experimental conditions were in three cases, case1: injected HRA from outer side and PC from inner side of double-channel lance, case2: injected HRA from inner side and PC from outer side of double-channel lance and case3: injected HRA and PC premixed. As a result, the combustion and gasification efficiency was increase in the order of case3, case2 and case1. 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.