セメント製造用流動層仮焼炉のDEM-CFD数値解析および実機検証

摘要

仮焼炉は，炉内において微粉炭を燃焼しセメント原料の主成分である石灰石の脱炭酸反応を行う装置である。三菱式流動層仮焼炉は原料や微粉炭の滞留時間が長く，比較的低い温度で微粉炭燃焼と原料の脱炭酸が行えるといわれているが，熱エネルギーの消費や製造コストをさらに低減するために，仮焼炉の助燃率（単位時間における仮焼炉への投入熱量と焼成工程全体への投入熱量との比率)，微粉炭のチヤー（固定炭素と灰分）反応率および原料の脱炭酸率の向上が求められている。%A numerical calculation method of the fluidized bed calciner for cement production including pulverized coal combustion, raw material decarbonation reaction and heat transfer was developed using the coupling simulation method of DEM - CFD (Discrete Element Method - Computational Fluid Dynamics). In addition, in order to shorten the calculation time, a coarse-grained model for DEM was used in the DEM-CFD. Based on this, the influence of the position and the number of pulverized coal blowing lines into the calciner on the characteristics of pulverized coal combustion and the property of raw material decarbonation was investigated. As a result, a modification plan to change pulverized coal blowing lines to promote pulverized coal combustion and raw material decarbonation was found from the calculation results, and the position and the number of pulverized coal blowing lines were changed from a single pulverized coal blowing line to two blowing lines in a commercial manufacture system. Then, the modified effectiveness and the validity of the numerical calculation method were verified by measuring actual gas composition and temperature distribution in the calciner before and after modifying.