Fuel enhancement by conversion of hotter waste CO 2 in flue gas with coke

Abstract

Considering the huge losses of high-temperature metallurgical waste heat and gases in steel works and the energy crisis on a worldwide scale, particularly the waste hotter gases in the flue of a converter that are emitted into air, a novel concept where coke is injected into the hotter gases for enhancement of fuel gas and reduction of CO₂ emissions into air is proposed. The effect of the surface structure of coke on the reactions of gas–solid phases was analysed using the t-plot method, and the transient gas products were described during coke injection. The energy change of the flue gas under various injecting schemes was discussed during the tests. The results show that an injecting scheme comprising an injecting pressure of 1.0 MPa, an inserted depth of 500 mm and an injecting mass rate of 18 kg min⁻¹ seems to be better. The value of the specific surface area of coke was 8.36 m² g⁻¹, while the coal was 20.59 m² g⁻¹. With the inserted depth at 400 and 500 mm, the recovery time of the flue gas was 545 and 565 s and the total calorific value accounted for 48.47 and 51.53%, respectively. Without injection, the average contents of CO, O₂ and CO₂ were 48.1, 1.01 and 23.3, whereas after injection the average contents of CO, O₂ and CO₂ were 56, 0.5 and 10.1%, respectively. As a result, this process reduces CO₂ emissions and increases energy of the flue gas.