The Design of the CASOH Process Pilot to Test the Decarbonisation of Blast Furnace Gas Using the Ca-Cu Chemical Loop
6 Pages Posted: 22 Nov 2022
Date Written: November 21, 2022
Abstract
We present the design features of a TRL7 pilot under construction in the Arcelor Mittal´s Gas Lab site in Asturias (Spain), to demonstrate the viability of the Calcium Assisted Steel-mill Off-gas Hydrogen (CASOH) process to decarbonise Blast Furnace Gases [1,2,3]. The work is carried out within the EU C4U project (https://c4u-project.eu/, [3]). The CASOH process relies on high-temperature solid looping reactions, carried out in a number of packed-bed reactors that continuously switch between three reaction stages. In a first stage (also called CASOH), there is carbonation of CaO by capture the CO2, including the CO2 formed by the catalysed Water Gas Shift of the CO contained in the BFG. In a second reaction stage, there is oxidation of the WGS Cu catalyst with air. In a third and final stage, there is the exothermic reduction of the CuO with a fuel gas, to drive the decomposition of CaCO3 and generate a concentrated CO2 gas stream while regenerating the CaO used in the first reaction stage. The CASOH TRL7 pilot has been designed to have a single reactor (with a thermally insulated bed of functional Ca and Cu materials of 5 m height and 0.5 m inner diameter), capable to alternate between all three reaction stages. The pilot will be operated at close to atmospheric pressure within the C4U project, but has enhanced capabilities to accommodate pressure swings of up to 10 bar in the future. It can treat 300 Nm3/h of BFG (about 0.3 MWth) from the AM industrial site and generate an equivalent amount of decarbonised N2/H2 rich-gas and up to 0.7 MWth of sensitive heat at high temperature in heat removal stages. First experimental results at TRL7 are expected by the end of 2022, but successful set of results have been obtained at smaller scale (TRL3-4) with the chosen functional materials (a commercial Cu-catalyst and a commercial limestone with adequate mechanical and chemical properties) and presented in other communications at GHGT16 [4,5].
Keywords: CO2 capture, calcium looping, chemical looping
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