Experimental investigation of thermochemical syngas production in a scrap iron-based oxidizer reactor for industrial decarbonisation

Abstract

The syngas production performance of scrap iron reacting with carbon dioxide and water steam was assessed under different operating conditions in a fixed bed oxidizer reactor. The syngas generation step is part of a novel process scheme encompassing the reutilization of iron scrap from steelmaking and the combined splitting of industrially captured carbon dioxide and steam into a syngas. At 1050 °C, a maximum volume percentage of 37 % carbon monoxide was detected in the product gas with the injection of 1 NL/min carbon dioxide. The carbon dioxide conversion was confirmed to be promoted by temperature. Subsequently, combined tests with carbon dioxide and water steam were carried out to assess the production and quality of the syngas (H2 and CO) by varying the reactants total flow rate, the iron bed mass and the reactants molar ratio. By decreasing the total reactants flow rate, the reactants splitting process was promoted and below a certain flow rate carbon dioxide splitting prevailed on that of water steam. By increasing the H2Ov/CO2 molar ratio, the splitting was enhanced for both species. In particular, for the tested flow rate the water splitting increased by 10% compared to 3.5% of the CO2 splitting. This indicated that a high H2Ov/CO2 ratio optimizes syngas production in the designed system. Finally, with H2Ov/CO2 = 6 and the optimal thermochemical syngas composition was achieved, including 41 % H2 and 12.1 % CO, being the remaining part constituted by CO2 when computed on a dry basis.