Typical case of carbon capture and utilization in Chinese iron and steel enterprises: CO2 emission analysis

Abstract

The CO2 emission intensity of the iron and steel industry has reached 2.0 tCO2/t steel, whereas the CO2 emission of the global iron and steel industry has exceeded 3.6 billion tons. Reduction of the CO2 emissions of the iron and steel industry is therefore the focus of this study. Based on the first set of tail gas captured from the CO2 converter smelting process of a lime kiln in China, this study compares the CO2 emissions of CO2-capture converter smelting processes after converter gas combustion, devises two system boundaries, and formulates four CO2 capture process paths. Through detailed calculation and analysis, the CO2 emission of chemical absorption is determined to be greater than that of pressure swing adsorption. Furthermore, the participation of CO2 in converter smelting is demonstrated to be able to reduce CO2 emission. An increase in CO2 concentration in the feed gas is conducive to reducing the CO2 emission of the CO2-capture converter smelting process. When the CO2 mixing ratio is 9.68%, a CO2 emission reduction of 25.32 kg CO2/t steel can be achieved. In 2020, China's long industrial processes will produce 954 million tons of crude steel; if the flue gas (80% CO2) is subjected to pressure swing adsorption after converter gas combustion, an annual CO2 emission reduction of 242 million tons can be reached.