H2-rich syngas generated from forestry waste gasification by recycling hot blast furnace gas

Abstract

H2-rich syngas injection and decarbonization of blast furnace gas are the main technical routes for achieving low-carbon iron-smelting in the iron and steel industry. In this study, a novel process of H2-rich syngas generated from forestry waste (FW) gasification by hot recycling blast-furnace gas (BFG) is proposed. A model of FW gasification by the hot BFG in an entrained-flow gasifier is constructed using Aspen Plus with a focus on minimizing Gibbs free energy. Meanwhile, the techno-economic analysis of H2-rich syngas generated from FW gasification is also evaluated via taking 36 tones/hr of FW gasification as the objective. The model is experimentally validated with gasification results derived from published studies. The technology analysis reveals that the optimum performance for H2-rich syngas generated from FW gasification by the hot BFG with total energy efficiency of 74.75 % is observed at a gasification temperature of 850 °C, steam/FW ratio of 0.18 kg/kg, and BFG/FW ratio of 2 m3/kg. The economic analysis indicated that the net present value (NPV), payback period (PBR), and internal rate of return (IRR) are in sequence as 336.70 M$, 2.40 yr, and 71.19 % assuming the cost of H2-rich syngas is 0.11 $/Nm3. Meanwhile, 1.67 kg syngas production yield and 1.9 kg CO2 recycled per kg of FW gasification by the proposed process. The proposed process is not only a competitive technology for H2-rich syngas generation, but also an effective strategy to reduce carbon-emitting.