Experimental Proof of Concept of Blast Furnace Gas Decarbonisation Via Casoh Process.

Abstract

The decarbonisation of Blast Furnace Gas (BFG) that is the main source of CO2 emissions in an integrated steel making plant, has been experimentally achieved in a lab-scale fixed-bed reactor, through the Calcium Assisted Steel-mill Off-gas Hydrogen production process (CASOH). The three main reaction stages of the CASOH process (H2 production via calcium-assisted water-gas-shift of BFG, Cu oxidation and CO2 sorbent regeneration) have been studied in detail using commercial Ca- and Cu-based materials readily available for scaling-up the process. The suitability of these materials in terms of stability and reactivity has been confirmed after multiple reaction cycles carried in a thermogravimetric analyzer resembling the operating conditions expected in the TRL-7 CASOH plant under construction. In the fixed-bed reactor, a product gas containing 40% vol. H2 in N2 (i.e. the maximum concentration allowed by the equilibrium) has been obtained during the CASOH stage using synthetic BFG mixed with steam (S/CO molar ratios up to 1.6) at pressures between 1 and 4 bar and bed temperatures of 650 ºC. The Cu oxidation carried out at 4 bar and relatively low temperature (675 ºC) has shown to be sufficiently fast to convert completely the O2 contained in the inlet gas giving rise to moderate temperatures in the oxidation front, which has minimized the CO2 leakage during this process stage. Finally, the reduction of CuO with synthetic BFG has provided the energy required to regenerate the CO2 sorbent (via CaCO3 calcination) producing a CO2-rich gas at the reactor exit.

Keywords: Hydrogen, Steel Mill Chemical Looping Combustion, Calcium Looping, Packed-bed Reactor

JEL Classification: Q40