Techno-economic assessment of retrofitting indirect-heated calcium looping using coal and biomass as fuels into an existing cement plant for CO2 capture

Abstract

The indirect-heated calcium carbonate looping (IH-CCL) process is an advanced carbon capture technology. It eliminates the need of an energy-intensive air separation unit that is required in the conventional oxy-fired calcium carbonate looping process, thereby potentially leading to lower energy consumption and cost. The IH-CCL process has not been well studied for application in the existing cement industry with minimized modification to the current plant. This paper presents a techno-economic feasibility assessment of retrofitting IH-CCL into an existing cement plant to better understand the CO2 emission reduction, energy performance, and economic costs. Solid waste-derived fuel (SWDF) containing 90–95% of wood is burnt for pre-calcination. Thermal coal is applied in the rotary kiln at which clinker is formed at a higher temperature. A model for process simulation using Aspen Plus and techno-economic analysis was established to supply options to the current cement plant based on different targets in CO2 capture (>80%) and the capital cost. Three integration scenarios, including the downstream integration, tail-end integration, and the full integration, were analyzed. A sensitivity analysis of the cost of CO2 avoided (CCA) was also performed, which revealed that the IH-CCL tail-end integration is recommended for retrofitting to existing cement plants due to the lowest CCA and very minor impact on the existing cement manufacture process. It was also concluded that although the full integration scenario offers the lowest specific primary energy consumption for CO2 avoided (SPECCA) and clinker cost, it may better suit greenfield cement plants as this option requires significant modifications.