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A dry sorbent post-combustion CO 2 capture process using a circulating fluidized bed (CFB) was developed to a 10 MWe scale. Particle attrition is a major challenge for many CFBs owing to the loss of particles and increased operating costs. Furthermore, predicting and alleviating the rate of particle attrition in an entire CFB is difficult owing to limited information on attrition in the riser and cyclone. This study experimentally investigated particle attrition in risers and cyclones and the effect of system scale-up using CO 2 adsorbent particles used in a 10 MWe scale CFB. Experiments were conducted in two types of CFBs to measure the attrition rate in the riser and cyclone for 22 and 12 h for each experimental condition. To verify the scaled-up effect, internals were added to the riser to measure the effect of the surface-area-to-volume ratio. Correlations for the attrition rate of CO 2 adsorbent particles in riser and cyclone were proposed, and a model for the scale-up effect was suggested. In the 10 MWe scale system, particle attrition mainly occurred in the cyclone (58.0 %) and riser (37.3 %) according to the calculation, and the calculated overall attrition rate reasonably matched the operational data. Figure: (a) Calculated attrition rate of CO 2 adsorbent particles in the circulating fluidized bed of 10 MWe scale CO 2 capturing process, and (b) effect of cyclone inlet gas velocity on the particle attrition rate in cyclone. [Display omitted] • Particle attrition mainly occur in the cyclone and riser of a CFB. • Attrition rate in cyclone was proportional to the square of the gas velocity. • The top size of fines formed by attrition in riser increased with gas velocity. • Attrition rate in the riser increases by increasing surface area. • Correlation for particle attrition rate in the riser and cyclone are proposed. [ABSTRACT FROM AUTHOR]

• No degradation of sorbent performance even after 128 h testing (168 cycles). • The best results were a CO 2 removal of 55%, regeneration heat energy of 4.2 GJ/tCO 2. • Sensitivity analysis was conducted with the goal of improving performance. • To achieve 90% CO 2 removal, the reaction rate should be at least twice as fast. • With improved reaction rates, a regeneration heat energy of 2.9 GJ/tCO 2 was achievable. Greenhouse gases, particularly carbon dioxide, have increased the Earth's average temperature by 1 °C, which has resulted in significant consequences for human life. To prevent further global warming and maintain a stable lifespan, it is imperative to achieve carbon neutrality. Post-combustion capture using an amine-based aqueous solvent is an advanced technology that has gained attention, but there are challenges such as corrosion, environmental impact, and energy consumption associated with it. This study aims to evaluate the performance of a polyethyleneimine-based sorbent in a circulating fluidized bed carbon dioxide capture unit and to determine the optimal operating conditions through sensitivity analysis. Various variables, including carbon dioxide concentration, water vapor content, desorber temperature, and sorbent residence time, were analyzed. The unit was continuously operated for 128 h even under challenging conditions with higher oxygen concentrations than the actual flue gases, and sorbent degradation was negligible. The results showed a 55 % carbon dioxide removal efficiency, a dynamic sorption capacity of 0.041 g-CO 2 /g-sorbent, and a regeneration heat energy of 4.2 GJ/tCO 2. Sensitivity analysis revealed that there was minimal improvement even with changes in the absorber structure and physical properties of the sorbent. Only an increase in the sorbent reaction rate had a significant effect. If the reaction rate were to double, the carbon dioxide removal efficiency would reach 90 %, with a dynamic sorption capacity of 0.068 g-CO 2 /g-sorbent and regeneration heat energy of 2.9 GJ/tCO 2. [ABSTRACT FROM AUTHOR]

This study aimed to provide a design and operational approach for a loop-seal, which is the heart of a circulating fluidized bed (CFB). Thousands of CFB systems use this non-mechanical valve to optimize performance by controlling the solids circulation rate while preventing gas mixing between reactors. Nevertheless, its design and operating guidance remains unclear because of its intricate flow characteristics, causing confusion in design and operation of the entire CFB. This study experimentally investigated the three most important elements while designing and operating loop-seal: conditions for initiating solids flow, the maximum obtainable solids flow rate, and quantitative control of solids flow rate. Experiments were conducted in a CFB, which simulated 3 MWth chemical looping combustion (CLC) system that is currently being developed. The onset of solids flow occurs when the gas drag force in horizontal passage overcomes the resistance force generated by the bed of particles. The maximum solids circulation rate was determined by solids height in the supply chamber and pressure around CFB loop. A correlation for quantitative control of solids flow in loop-seal was proposed by the relationship between the gas drag force and particle velocity. Finally, operational conditions for the loop-seal in 3 MWth CLC were proposed. Operating conditions of the loop-seal in 3 MWth chemical looping combustion system derived in this study. [Display omitted] • Flow characteristics in loop-seal was analyzed and design factors were confirmed. • Solid flow started after overcoming resistance force by solid in horizontal path. • Particle velocity in horizontal path increased linearly by drag force of gas. • Solid height in standpipe determined the maximum solid circulation rate. • 3 Nm3/hr of Q sup,in was required for solid circulation of 15 kg/s in 3 MWth CLC. [ABSTRACT FROM AUTHOR]