Change of coke structure and behavior of fine generation during gasification of coke sphere in high temperature region

Abstract

According to the pulverized coal injection (PCI) into blast furnace (BF), the fine generation of coke in the lower part of BF especially around raceway has come to an important problem for stable operation. In this study, three kind of spherical cokes were used for gasification experiment simulated to the lower part of BF (1500-1700°C). Each cokes before and after experiments were examined the fine generation using I type tumbler for single particle which was developed by authors. The behavior of fine generation in high temperature can not predict from the conventional industrial tests such as CSR, Df, CRI and JIS-RI, because the industrial tests are carried out around 1000°C and the apparent reaction rate of coke consist of not only a chemical reaction rate but also a diffusion of gas in pore, depending on the reaction temperature. Especially in higher temperature than 1500°C, graphitization behavior will affect significantly on the apparent reaction rate. Then, structure change of coke after experiment was investigated using fluorescent resin and the change of porosity from the surface was clarified. The reaction zone from the surface to the inside was determined by computer aided image analysis. It was found that the amount of coke remained in the reaction zone was in good agreement with that of fine generated from coke.