Abstract
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•New concept & process for direct capture of carbon dioxide in lime production.•Use of an aqueous hydrogen peroxide mixture as an oxidiser instead of air.•Adiabatic flame temperature with aqueous hydrogen peroxide mixture as oxidiser.•Process models in Aspen Plus and comprehensive sensitivity analysis.
Lime production is a highly carbon-intensive process for which new technology for carbon dioxide capture is needed, if it is to meet zero-emission targets. Hydrogen peroxide is an oxidant that decomposes exothermically to oxygen and water. That is, it can potentially be used as an alternative oxidant to air for the combustion of the hydrocarbon fuels, thereby avoiding the dilution of the product flue gas with nitrogen, which is otherwise present in air combustion, and enabling the direct capture of carbon dioxide. This paper presents a preliminary thermo-dynamic assessment of this potential use of hydrogen peroxide, here introduced as an aqueous solution The adiabatic flame temperature for the combustion of methane or carbon (as surrogates for natural gas and coal/biomass respectively) is estimated for various concentrations of hydrogen peroxide in water and compared with those for the combustion of methane and carbon with air. Also reported is a plausible approach for heat recovery in the lime-manufacturing process, which provides the enthalpy for vaporisation of the aqueous solution of hydrogen peroxide by heat recovery from the flue gases. The performance of the proposed process was evaluated using Aspen Plus software. The net carbon dioxide captured, emitted and avoided are compared with those from a reference cycle, together with the first law efficiency of the cycle and the fraction of energy supplied from the fuel. Also reported is the sensitivity of the performance to variation in key operating parameters. This reveals the importance of the carbon footprint of the upstream processing options to produce the hydrogen peroxide on the net carbon dioxide emissions of the process. The potential viability and challenges of the proposed system are also discussed.