Carbonate Looping For Intermediate Temperature Co2 Capture: Evaluating The Sorption Efficiency Of Mineral-Based Mgo Promoted With Caco3 And Alkali Nitrates

This work focused on enhancing the CO2 capture kinetics of magnesite-derived MgO via alkali nitrate and mineral CaCO3 promoters for its application in the Carbonate Looping technology at intermediate temperatures (≤400°C). Alkali salts had a prominent role by shifting into molten state to offer a favorable carbonation pathway and allow a significantly higher CO2 uptake than non-promoted MgO, while their synergy with CaCO3 bestowed even better sorption activity. MgCO3 and CaMg(CO3)2 were detected as the main carbonate products, with the latter exhibiting faster formation rate. The sorbent with CaCO3 and alkali salts to MgO molar ratios of 0.05 and 0.20 respectively attained an uptake of 7.2 moles CO2/kg of sorbent when exposed to a 30%CO2 flow at 300°C with only 6% activity loss after 50 carbonation cycles, proving the applicability of the materials. Despite the cyclic sorption activity loss due to sintering and dewetting, alkali salts redistribution enabled a stable performance under proper conditions

One-Dimensional Heterogeneous Reaction Model of a Drop-Tube Carbonator Reactor for Thermochemical Energy Storage Applications

Calcium looping systems constitute a promising candidate for thermochemical energy storage (TCES) applications, as evidenced by the constantly escalating scientific and industrial interest. However, the technologically feasible transition from the research scale towards industrial and highly competitive markets sets as a prerequisite the optimal design and operation of the process, especially corresponding reactors. The present study investigates for the first time the development of a detailed, one-dimensional mathematical model for the steady-state simulation of a novel drop-tube carbonator reactor as a core equipment unit in a concentrated solar power (CSP)-thermochemical energy storage integration plant. A validated kinetic mathematical model for a carbonation reaction (CaO(s) + CO2(g) → CaCO3(s)) focused on thermochemical energy storage conditions was developed and implemented for different material conditions. The fast gas–solid reaction kinetics conformed with the drop-tube reactor concept, as the latter is suitable for very fast reactions. Reaction kinetics were controlled by the reaction temperature. Varying state profiles were computed across the length of the reactor by using a mathematical model in which reactant conversions, the reaction rate, and the temperature and velocity of gas and solid phases provided crucial information on the carbonator’s performance, among other factors. Through process simulations, the model-based investigation approach revealed respective restrictions on a tailor-made reactor of 10 kWth, pointing out the necessity of detailed models as a provision for design and scale-up studies