The energy consumption and carbon emission of the integrated steel mill with oxygen blast furnace

•A comprehensive model including the stack and bosh model, combustion model and gas recycling system model is developed for the new ironmaking process.•The material and energy flows of the integrated steel mill were developed on the basis of the real operation parameters.•The energy consumption and carbon emission of the integrated steel mill with oxygen blast furnace are investigated by the material and energy flows.

As an energy intensive industry, China's iron and steel industry is faced with the challenges of energy saving and carbon emission reduction. The oxygen blast furnace with top gas recycling (TGR-OBF), as a new iron-making process, can significantly reduce CO2 emission. To obtain parameters on the material and energy flows of this process, a TGR-OBF model was established, which comprises the oxygen blast furnace, the top gas removal process and the preheating units. The energy consumption and carbon emission of the integrated steel mill (ISM) with the TGR-OBF was analyzed based on the material and energy flows. The analysis concluded that TGR-OBF significantly decreased the generation and consumption of metallurgy gas. Due to the consumption of large amount of oxygen and the removal of CO2, the ISMs with the TGR-OBF purchased 2.8 times more electricity than the conventional ISM, while the energy consumption of the ISM with the TGR-OBF was reduced to 14.4 GJ per ton crude steel, thanks to the reduction of coking coal consumption. Compared with the conventional ISM, the direct CO2 emission from the ISM with the TGR-OBF was reduced by 26.2%, and it could be reduced by 56.5% when CO2 capture and storage realized. If the net CO2 emission from the ISM with the TGR-OBF is calculated based on the world average CO2 emission factors, it would be 1.75 t/t crude steel (without CO2 capture and storage) and 1.17 t/t crude steel (with CO2 capture and storage).