Simulation of a Moving Bed Chemical Looping System for Electricity Production from Coal Via Chemical Looping Water Splitting

Coal is an essential energy source for modern industry. However, being the most carbon-intensive fossil fuel, the combustion of coal for power generation contributes to a significant proportion of greenhouse gas emissions. To reduce CO₂ emissions from coal-fired power plants, various approaches can be adopted, such as the pre-combustion CO₂ capture and the post-combustion CO₂ capture methods. However, these CO₂ capture methods are usually energy intensive. For example, the energy penalty of an amine-based post-combustion CO₂ absorption system can reach up to 20-30% of the total power production from the plant.

Chemical looping technology is a versatile platform for industrial material and energy conversions, and it provides promising alternatives for CO₂ capture from coal-fired power plants. This work studies the application of chemical looping water splitting (CLWS) technology to replace the gasification unit and pre-combustion CO₂ separation units in a conventional integrated gasification combined cycle (IGCC) process for electricity production. The CLWS system consists of a reducer, an oxidizer and a combustor. In the reducer, coal reacts with metal oxides to be converted into CO₂. The reduced metal oxides react with water in the oxidizer to produce H₂. Finally, the metal oxides are fully regenerated in the combustor by reacting with air. H₂ is then combusted in a combined cycle to generate electricity. The CLWS process is simulated in ASPEN Plus, and the operating parameters such as the metal oxides composition and the system pressure are adjusted to maximize the power production. Process simulations indicate that the CLWS process can achieve an 18% improvement (relative percentage) in electrical efficiency compared to conventional IGCC systems, demonstrating the great potential of the CLWS technology for electricity generation with a higher energy efficiency and minimal CO₂ emissions.