COKE DEGRADATION MECHANISM AND SUPPRESSIO N MEASURES DURING HIGH-RATEPULVERIZED COAL INJECTION

The coke degradation mechanism was considered in order to suppress the fine coke increase during high-rate pulverized coal injection. The fo llowing conclusions were derived as a result of model experiment. (1) The reasons why the fine coke increases at the tuyere level during hig h-rate pulverized coal injection are the degraded coke surface existen ce because of the lack of gasification by O-2 and the increase of gasi fication by CO2 in the raceway. (2) The use of high reactive coke is e ffective in order to suppress the coke degradation. (3) The permeabili ty in the lower part of the blast furnace is controlled by the fine co ke amount at the bosh level during high-rate pulverized coal injection . The decrease of load on the coke bed is effective in order to suppre ss the coke degradation at the bosh level. (4) In order to apply the m odel experimental results to the actual blast furnace, it is necessary to consider the effect of coke strength at room temperature and the d ecrease of coke surface strength after gasification during the use of high reactive coke.