製銑システムにおけるエクセルギー消費とCO₂排出量の解析

抄録

Exergy and CO₂ analyses were carried out for three ironmaking systems of blast furnace with pulverized coal injection, SC system proposed by Smitomo Metal and smelting reduction. Blast furnace and SC ironmaking systems were analysed based on operating data reported. For smelting reduction system, operating data was calculated by using the kinetic mathematical model under the various condition of prereduction degree, rate of post combustion and heat recovery efficiency. The exergy loss among the systems have been compared for obtaining detail information on the system evaluation from the point of view of energy consumption. Emission of carbon dioxide discharged from the systems were also compared for environmental preservation.
The results obtained are as follows ;
1) Exergy loss in a conventional ironmaking system of 10 000 t/d was decreased from 9.3 GJ/thm to 8.0 GJ/thm by injecting 110 kg/thm pulverized coal.
2)Exergy loss in SC system of 2 400 t/d was 7.1 GJ/thm.
3)Exergy loss in smelting reduction system depended remarkably on prereduction degree in a shaft furnace or a fluidized bed. As prereduction degree increased from 0 to 80%, exergy loss in the system decreased from 11.8 GJ/thm to 6.2 GJ/thm.
4) Conventional ironmaking system discharged about 520 kg-C/thm, while CO₂ emitted from the smelting reduction system depended considerably on ratio post combustion and heat efficiency.