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Abstract: The mass produced K2CO3/Al2O3 sorbents were tested for their CO2 sorption capacity by a 2000Nm3/h (0.5MW) CO2 capture pilot plant, which was built for unit 3 of Hadong thermal power station in 2010. After the commissioning, CO2 capture pilot plant was tested with the flue gas from the power station for 60days. To assess the effect of SO x in the flue gas of coal-fired power plant on the sorbent, the new and used K2CO3/Al2O3 sorbents were analyzed by FE-SEM, IC, EPMA, XRD and XPS. The results show that SO x of 10–40ppm in flue gas was reacted with K2CO3, but not with any other support materials, and formed K2SO4. And also, it is proved that the formed K2SO4 was quite stable in the range of 180–550°C. [Copyright &y& Elsevier]

Abstract: Korea Institute of Energy Research (KIER) and Korea Electric Power Research Institute (KEPRI) have developed the carbon dioxide (CO2) capture system using dry regenerable sorbents since 2002. The principle of the CO2 capture with regenerable solid sorbents is the reversible reaction between potassium carbonate and potassium bicarbonate in a thermal-swing process. Based on this reaction, we developed a bench scale unit (BSU) which treated 100 Nm3/h of flue gas in late 2006. The BSU consisted of a transport fluidized-bed carbonator, cyclones, a loop-seal, and a bubbling fluidized-bed regenerator. We have tested the BSU facility using a slip stream of the real flue gas from a coal-fired circulating fluidized bed combustor located at KIER in order to check the performance of CO2 removal, the stability of operation. The results showed that more than 80% of CO2 removal had been maintained during more than 50 hour continuous operation and its maximum reached at the 85% level. Those results indicated that the CO2 capture system using solid sorbents developed here could be applied to coal-fired power plant. In the meanwhile, we set the small scale unit which consists of two bubbling beds for carbonation and regeneration in order to investigate the effect of several operating variables on the CO2 removal. The performance of the small scale unit was investigated through the continuous operation with solid circulation under the same experimental conditions as the BSU facility. The CO2 removal of the small scale unit was reached at the 83% level with the inlet CO2 concentration of 10 vol.%. The CO2 removal increased as the water vapor content in the inlet flue gas stream, regeneration temperature, and solid circulation rate increased while it decreased as the gas velocity of the carbonator and carbonation temperature increased. It was found that the performance of the CO2 removal was very sensitive to the water vapor content in the inlet gas stream and the gas velocity of the carbonator (gas-solid contact time in the carbonator). The construction of 0.5 MW scale pilot plant based on the results of BSU at KIER has been finished in late 2009 at the Hadong Coal-Fired Power Plant, Korea Southern Power Company. The overall performance of pilot plant showed very promising and its CO2 capture performance reached at the 85% level. A 10 MW scale CO2 capture plant next development step after 0.5 MWe at the Hadong Coal-Fired Power Plant will be started to construct at the same site in late 2011. [Copyright &y& Elsevier]

Abstract: Korea Institute of Energy Research (KIER) and Korea Electric Power Research Institute (KEPRI) have been developing a CO2 capture technology using dry sorbents. The CO2 removal in dry sorbent CO2 capture system consists of two reactors for carbonation and regeneration. We used dry sorbent manufactured by spray-drying method contains potassium carbonate, which was supplied by KEPRI in order to investigate the sorbent performance in continuous operation mode with solid circulation between a fast fluidized bed type carbonation reactor (13.5 m tall pipe of 0.075 m i.d.) and a bubbling fluidized bed type regeneration reactor (2 m tall bed of 0.25 m i.d.). We used the real flue gas from 2MW coal-fired circulating fluidized bed combustor to check possibility of deactivation of dry sorbent by contaminants such as SO x and NO x in the real flue gas for the 100 Nm3/hr of flue gas treatment facility. The residence time of the dry sorbents was about 3 seconds and 15 minutes in the carbonation reactor and the regeneration reactor, respectively. The CO2 removal during 2 hrs in the whole experiments and the average CO2 removal was above 70%. From the experiment, it was revealed that the removal of heat of sorption in the carbonation reactor was important to increase CO2 removal. During the experiments continuous and smooth operation were accomplished with solid circulation between two reactors. These results indicate that CO2 capture process using potassium carbonate solid sorbent is applicable for CO2 capture in the coal-fired flue gas. [Copyright &y& Elsevier]

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]

Oxy-combustion with a circulating fluidized bed (Oxy-CFBC) can facilitate the separation of high CO 2 concentration and reduce emissions by biomass co-firing. This study investigated Oxy-CFBC characteristics such as temperature, solid hold-up, flue gas concentrations including CO 2 , pollutant emissions (SO 2 , NO, and CO), combustion efficiency and ash properties (slagging, fouling index) with increasing input oxygen levels (21–29 vol%), and biomass co-firing ratios (50, 70, and 100 wt% with domestic wood pellet). The possibility of bio-energy carbon capture and storage for negative CO 2 emission was also evaluated using a 0.1 MW th Oxy-CFBC test-rig. The results show that combustion stably achieved with at least 90 vol% CO 2 in the flue gas. Compared to air-firing, oxy-firing (with 24 vol% oxygen) reduced pollutant emissions to 29.4% NO, 31.9% SO 2 and 18.5% CO. Increasing the biomass co-firing from 50 to 100 wt% decreased the NO, SO 2 and CO content from 19.2 mg/MJ to 16.1 mg/MJ, 92.8 mg/MJ to 25.0 mg/MJ, and 7.5 mg/MJ to 5.5 mg/MJ, respectively. In contrast to blends of sub-bituminous coal and lignite, negative CO 2 emission (approximately −647 g/kW th) was predicted for oxy-combustion only biomass. • Oxy-combustion with a 0.1 MW th CFB was operated. • Effect on the various O 2 concentrations and biomass firing ratios investigated. • Stable shift from air-to oxy-fired easily achieved above 90% (dry) CO 2 flue gas. • Oxy-fired NO and SO 2 emissions lower than those of air-fired. • CO 2 negative emission from biomass-only oxy-firing expected (−647 g CO 2 /kW th). [ABSTRACT FROM AUTHOR]

For stable carbon capture utilization and storage, highly-pure CO 2 content and low pollutant emissions must be maintained throughout oxy-coal firing operation; however, studies on combining absorbent addition and oxidant staging combustion to eliminate simultaneous nitrogen oxides (NO, N 2 O) and sulfur dioxide (SO 2) have not been reported. Accordingly, the purpose of this study was to investigate the effects of oxidant staging and limestone addition on the reductions of NO, N 2 O, and SO 2 emissions in an oxy-circulating fluidized bed combustor at 25% and 31% input oxygen. The operating parameters considered in this study were: oxidant compositions; corresponding flow rate ratios; primary, secondary, and tertiary oxidants (PO, SO, and TO, respectively); TO supply heights; and limestone addition. The results revealed that compared to the TO supply heights, increasing TO flow rate was more effective at reducing the nitrogen oxide emissions. Under an optimal flow rate ratio (PO:SO:TO = 70:10:20) and TO height (6.4 m), NO, N 2 O, and SO 2 emissions were ≈7.4, 4.2 and 4.1 mg MJ−1, respectively. The increase in SO 2 emission caused by the application of oxidant staging could be effectively decreased by 60.6% without impacting combustion performance via limestone injection into the combustor; effectively facilitating the production of >86 vol% CO 2. These findings can serve as valuable references for future designs, and the efficient operation of oxy-coal combustion plants constructed at larger scales, thereby ensuring highly-pure CO 2 content and low pollutant emissions. • Explored staging combustion in oxy-circulating fluidized bed on emissions reductions. • Tertiary oxidant (TO) flow rate was more effective at reducing NO, N 2 O emissions. • Optimal ratio, TO height reduced NO, N 2 O, and SO 2 by 7.4, 4.2, and 4.1 mg MJ−1 • Limestone injection decreased SO 2 emissions by 60.6% without impacting performance. • Provides a valuable reference for future designs of oxy-coal combustion plants with the EHE. [ABSTRACT FROM AUTHOR]

[Display omitted] • The working capacity and stability of absorbent were studied for CO 2 capture. • MPS-supported epoxide-functionalization of PEHA absorbent was synthesized. • PO-PEHA/MPS adsorbent exhibited the working capacity of 1.8 mmol g−1 in 20 cycle. • When the adsorption time was reduced, the regeneration heat was 2.86 GJ tCO 2 -1. • Adsorbent that is regenerated in 100% CO 2 , not inert (N 2 , He) conditions was developed. N -functionalized solid adsorbents have been studied for post-combustion CO 2 capture. Most studies have focused only on the adsorption condition of the adsorbents. Few studies have focused on the regeneration condition of adsorbents. Regeneration is required under the condition of 100 % CO 2 for high-purity CO 2 separation. Regeneration under inert conditions such as N 2 or He, not under the condition of 100 % CO 2 regeneration are required additional cost for high-purity CO 2 separation. In this study, a macroporous silica (MPS) support, which combined a high surface area, large porosity and large pore volume, was selected as the support to achieve high CO 2 capture performance. Pentaethylenehexamine (PEHA) was selected because of its high amine content, high adsorption capacity, high thermal stability, and low cost. The epoxide functionalization of PEHA was used to suppress the urea formation under regeneration conditions. The working capacity and cyclic stability of epoxide functionalization of MPS-based PEHA adsorbents were investigated. A working capacity of 1.8 mmol g−1 was maintained by repeating adsorption and desorption experiments 20 times under an adsorption condition of 15 % CO 2 and a desorption condition of 100 % CO 2. Additionally, the stability of the adsorbent under a 100 % CO 2 regeneration condition was confirmed by maintaining the working capacity constant during 20 repeated adsorption and desorption cycle experiments. When the adsorption time was reduced to minimize H 2 O adsorption, the regeneration heat of the adsorbent was 2.86 GJ tCO 2 -1. These results demonstrated that the regeneration ability was excellent under the condition of 100 % CO 2 , which is the actual process application condition. This approach is promising for industrial applications of CO 2 capture technology. [ABSTRACT FROM AUTHOR]