Operation Window and Carbon Emission of the Blast Furnace with Natural Gas and Pulverized Coal Co-injection

The injection of pulverized coal into blast furnaces has alleviated the demand for metallurgical coke, and co-injection technology combining natural gas and pulverized coal with high oxygen enrichment has the potential to further reduce coke use and hence CO2 emissions. This work presents a steady-state operational model for the co-injection of natural gas and pulverized coal into blast furnaces developed based on mass and energy balance. With the support of industrial data from the commercial blast furnace, the matching relationship between natural gas rate, pulverized coal injection rate, and oxygen enrichment is quantitatively examined under the constraints of raceway adiabatic flame temperature and top gas temperature. The effect of natural gas rate on coke rate and CO2 emission reduction is investigated. The results show that increasing natural gas injection rate, lower pulverized coal rate and higher oxygen enrichment maintains a constant raceway adiabatic flame temperature and coke rate. Under the optimal operating conditions, the pulverized coal, coke rate, and CO2 emissions are reduced by 30.2%, 7.3% and 6.2%, respectively. The model and its results are expected to be helpful for a better understanding co-injection of natural gas and pulverized coal into blast furnaces, as well as contribute to reducing coke rate, pulverized coal rate, and CO2 emissions.