Towards decarbonisation of sugar refineries by calcium looping: Process integration, energy optimisation and technoeconomic assessment

Abstract

The sugar refinery process as a food industry is at the pinnacle of the energy hierarchy. Depending on the source of carbon in this industry that could be either from biomass or fossil fuel hydrocarbons, this sector has the potential to become a carbon–neutral or negative industry depending on the type of fuel for power generation. This work will deliver a new proof of concept model for simultaneous sugar refining and carbon capture, thereby transforming sugar into the carbon negative commodity which relies on the utilisation of CO2 and fresh lime in the sugar refineries carbonisation tanks and in return byproduction of calcium carbonate that can be converted in the calciner of a calcium looping process. This study begins with the design and development of the calcium looping (CaL) process for the integration to the sugar refineries using various coupled and decoupled scenarios for the boiler units based on the type of the fuel, continues with an energy optimisation and techno-economic assessment of the proposed process, and finally culminates with the parametric study on the thermodynamic and economic performance of the sugar refinery retrofitted with the calcium looping. The process simulations revealed that the integrated CaL-sugar refinery can support the electricity exporter by installation of an onsite steam cycle which is able to generate electricity from surplus carbonation heat. The cost of CO2 avoided for integration of CaL to the reference sugar refinery for natural gas boilers and calciner will be 62 £/tCO2 which drops to 25 £/tCO2 if the carbon tax is considered in the analysis and negative carbon emissions are credited. This is equivalent to 61% costs reductions associated refining sugar combined together with carbon capture and storage (CCS).