41 results on '"Calcium Looping"'
Search Results
2. Thermochemical Energy Storage Performances of Steel Slag‐Derived CaO‐Based Composites
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Shengbin Bai, Chuanwen Zhao, Yuning Chen, Yue Zhou, Zhiqiang Wang, and Jian Sun
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Materials science ,General Chemical Engineering ,Concentrated solar power ,General Chemistry ,Composite material ,Industrial and Manufacturing Engineering ,Energy storage ,Calcium looping - Published
- 2020
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3. A thermochemical reaction and kinetic characteristic study of municipal sludge in the atmosphere of treated flue gas from calcium looping (Ca‐L)
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Xiaojun Yang, Lihui Zhang, Songshan Cao, Feng Duan, Yuyi Liu, Zhi Li, and Jun Cao
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Flue gas ,Environmental Engineering ,Chemistry ,020209 energy ,Thermal decomposition ,Analytical chemistry ,02 engineering and technology ,Activation energy ,Kinetic energy ,Decomposition ,Atmosphere ,020401 chemical engineering ,Thermal ,0202 electrical engineering, electronic engineering, information engineering ,Environmental Chemistry ,0204 chemical engineering ,Calcium looping - Abstract
In this study, an in situ weighting system was used to study the thermal behavior of dried municipal sludge (MS) in the flue gas exiting from calcium‐looping (Ca‐L) process. The results showed that mass loss peak, initial decomposition temperature, and decomposition complete temperature moved to high‐temperature zone with increased heating rate. However, they moved to low‐temperature zone at higher O2 and CO2 concentrations. Apparent activation energy (E) and preexponential factor (A) increased with the increase of heating rate and O2 concentration and decreased with the increase of CO2 concentration. The heating rate has the greatest effect on the thermal decomposition of dried MS. With the heating rate increasing, the maximum mass loss peak occurred from 301 to 493°C, the corresponding E and A increased from 36.14 to 45.69 kJ mol−1 and from 29.58 to 321.4 min, respectively. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2020
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4. Kinetic analysis about the CO 2 capture capacity of lime mud from paper mill in calcium looping process
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Rongyue Sun, Jiangming Ye, and Rui Xiao
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Materials science ,lime mud ,lcsh:T ,business.industry ,calcium looping process ,Kinetic analysis ,Paper mill ,engineering.material ,Pulp and paper industry ,complex mixtures ,CO2 capture ,lcsh:Technology ,General Energy ,kinetics ,Scientific method ,parasitic diseases ,engineering ,lcsh:Q ,lcsh:Science ,Safety, Risk, Reliability and Quality ,business ,Calcium looping ,Lime - Abstract
Lime mud, a kind of industrial waste that produced in paper mill, was proposed as CO2 sorbent in calcium looping process. The carbonation performance of the lime mud was investigated in a dual‐fixed bed reactor (DFR) and a thermogravimetric analyzer (TGA). The carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by a surface reaction‐controlled kinetic model. The results show that the lime mud presents much poorer carbonation performance during the chemical reaction controlled stage compared with the limestone, mainly due to the high content of chlorine in the lime mud. A prewash treatment process was used to decrease the chlorine content to mitigate the sintering of the lime mud when calcined at high temperature. After prewash treatment, the prewashed lime mud shows much higher CO2 capture capacity during the chemical reaction controlled stage compared with the lime mud. A prolonged carbonation process successfully further enhances the microstructure and improves the carbonation performance of the prewashed lime mud in the chemical reaction controlled stage. The lime mud can be effectively used as CO2 sorbent in calcium looping process after prewash treatment and the following prolonged carbonation treatment.
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- 2020
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5. Coupled CO 2 capture and thermochemical heat storage of CaO derived from calcium acetate
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Tao Wang, Jianli Zhao, Chaoying Sun, Zeyan Wang, Yingjie Li, and Xianyao Yan
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Acetic acid ,chemistry.chemical_compound ,Environmental Engineering ,Materials science ,chemistry ,Chemical engineering ,Environmental Chemistry ,chemistry.chemical_element ,Calcium ,Thermal energy storage ,Calcium looping - Published
- 2020
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6. Enhancement of CaO‐based sorbent for CO 2 capture through doping with seawater
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Belén González, John Kokot-Blamey, Paul S. Fennell, and Commission of the European Communities
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Environmental Engineering ,Sorbent ,Materials science ,Chemical engineering ,Doping ,Environmental Chemistry ,Seawater ,0401 Atmospheric Sciences ,0502 Environmental Science and Management ,Calcium looping - Abstract
Limestone can be used to generate a sorbent suitable for CO2 capture via the reversible carbonation of CaO, in a process often referred to as calcium looping. This sorbent loses reactivity to CO2 upon cycles of carbonation and calcination (the reverse of carbonation). Several methods of improving sorbent performance have previously been investigated, including by generating synthetic sorbents or simple doping. Here, we demonstrate, for the first time, that sorbent performance can be enhanced by simple doping with seawater. This effect is consistent across five different limestones investigated and can be enhanced by steam addition. This would be a simple and inexpensive method for improving sorbent performance in calcium looping processes. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2020
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7. Pore and fractal descriptions of a modified CaO‐based sorbent for sequence SO 2 /CO 2 capture behavior
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Feng Duan, Qing Wu, Liu-Qing He, and Lihui Zhang
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Environmental Engineering ,Materials science ,Fractal ,Sulfation ,Sorbent ,Chemical engineering ,Environmental Chemistry ,Fractal dimension ,Calcium looping ,Sequence (medicine) - Published
- 2019
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8. A study of the synergistic effects of Mn/steam on CO 2 capture performance of CaO by experiment and DFT calculation
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Zeyan Wang, Wan Zhang, Xiaotong Ma, Jianli Zhao, and Yingjie Li
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Environmental Engineering ,Materials science ,Carbonation ,Doping ,technology, industry, and agriculture ,food and beverages ,02 engineering and technology ,010501 environmental sciences ,Combustion ,complex mixtures ,01 natural sciences ,humanities ,law.invention ,Periodic density functional theory ,020401 chemical engineering ,X-ray photoelectron spectroscopy ,Chemical engineering ,law ,Environmental Chemistry ,Calcination ,0204 chemical engineering ,Porosity ,Calcium looping ,0105 earth and related environmental sciences - Abstract
Novel Mn‐doped CaO was prepared by the combustion method. The CO2 capture performance of Mn‐doped CaO, carbonated in the presence of steam and under severe calcination conditions (950°C and 70% CO2/30% N2) during calcium looping cycles, was investigated in a dual fixed‐bed reactor. The intercoupling effects of Mn and steam on CO2 capture by CaO were also studied. Doping of Mn in CaO by the combustion method greatly improved the CO2 capture capacity of CaO. The carbonation conversions of Mn‐doped CaO increased with increasing steam concentration from 0 to 15%. When the molar ratio of Mn/Ca was 0.75 : 100, Mn‐doped CaO achieved the highest CO2 capture capacity. Under severe calcination conditions, the carbonation conversion of Mn‐doped CaO, where the molar ratio of Mn to Ca = 0.75 : 100 in the presence of 15% steam, was about 0.4 after ten cycles (carbonation for 5 min at 650°C under 15% CO2/15% steam/N2), which was 4.38 times as high as that of the original CaO in the absence of steam. The cyclic CO2 capture capacities of CaO were improved by Mn and steam. Synergistic enhancement effects of Mn and steam on the CO2 capture capacities of CaO were also found. The effect of steam on the carbonation conversion of Mn‐doped CaO was stronger than that of the original CaO. Mn in the presence of steam showed a more positive effect on CO2 capture by CaO. X‐ray photoelectron spectroscopy analysis showed that doping of Mn in CaO enhanced the transport of electrons in the carbonation of CaO, which helped to increase the carbonation rate. When steam was present in the carbonation, Mn‐doped CaO possessed a more porous structure and smaller CaO grains than the original CaO during the cycles. Simulation calculations using periodic density functional theory (DFT) showed that CO2 molecules were easier to absorb on CaO owing to the doping of Mn and the presence of steam. The synergistic enhancement effects of Mn and steam on CO2 captured the performance of CaO. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2019
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9. CO2 capture and attrition performance of competitive eco-friendly calcium-based pellets in fluidized bed
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Edward J. Anthony, Lunbo Duan, and Chenglin Su
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Cement ,Environmental Engineering ,Materials science ,Abrasion (mechanical) ,Pellets ,02 engineering and technology ,010501 environmental sciences ,engineering.material ,Elutriation ,021001 nanoscience & nanotechnology ,01 natural sciences ,Breakage ,Fluidized bed ,engineering ,Environmental Chemistry ,Composite material ,0210 nano-technology ,Calcium looping ,0105 earth and related environmental sciences ,Lime - Abstract
A system incorporating spent bleaching clay (SBC) into the calcium looping (CaL) process has been proposed. In this paper, prepared sorbents doped with regenerated SBC and cement were tested in a bubbling fluidized bed (BFB) to examine in detail their cyclic CO2 capture capacity and attrition properties. The results revealed that the cyclic CO2 capture capacity of pellets modified by pyrolyzed SBC and/or cement showed significantly better performance than limestone, which is consistent with the thermogravimetric analyzer (TGA) results. This is due to the improvement of pore structure and enhanced sintering resistance created by adding support materials to the sorbent. The elutriation rates of the composites prepared with pyrolyzed SBC and/or cement were consistently lower than for crushed limestone. Scanning electron microscopy (SEM) images indicated that the pellets possessed higher sphericity than limestone particles, thus reducing surface abrasion. Limestone exhibited a high attrition rate (diameter reduction rate) of 10.7 μm/cycle, which could be eliminated effectively by adding regenerated SBC and/or cement. ‘L‐5PC‐10CA’ (85% lime/5% pyrolyzed SBC/10% cement) exhibited an attrition rate of only 7.9 μm/cycle. Based on the analysis of breakage and probability density function (PDF) for particle size distribution, it appeared that pellets without cement experienced breakage (mostly chipping and disintegration) and surface abrasion, whereas ‘L‐10CA’ (90% lime/10% cement) and ‘L‐5PC‐10CA’ mainly suffered surface abrasion, combined with some chipping. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2018
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10. Explaining steam-enhanced carbonation of CaO based on first principles
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Lunbo Duan, Hongjian Tang, Tianyi Cai, Peng Yang, and Zhao Sun
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education.field_of_study ,Flue gas ,Environmental Engineering ,Materials science ,Carbonation ,Population ,02 engineering and technology ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,Co2 adsorption ,01 natural sciences ,Adsorption ,Chemical engineering ,Environmental Chemistry ,Molecule ,Density functional theory ,0210 nano-technology ,education ,Calcium looping ,0105 earth and related environmental sciences - Abstract
Calcium‐based sorbents have been regarded as effective agents for capturing CO2 from industrial flue gas. Recent studies have shown that steam can enhance the carbonation performance of calcium‐based sorbents. In this paper, a CaO (001) surface was made to investigate the micro‐level mechanism of steam‐enhanced carbonation based on first principles calculations. Charge transfer and bond population were calculated to evaluate an interaction effect between adsorbates and the CaO (001) surface. Individual adsorption of CO2 and H2O was compared with binary adsorption and co‐adsorption of the two molecules on the CaO (001) surface, based on dispersion‐corrected density functional theory (DFT‐D) calculations. First, the predicted adsorption energies suggest the O‐top site is the best site. It forms carbonate‐like structure and hydroxyl‐like structure for the individual adsorption of CO2 and H2O. Binary adsorption calculations indicate that H2O is more easily adsorbed by the CaO (001) surface than CO2. The adsorption of H2O and CO2 adsorption are promoted in comparison with their individual adsorption on the CaO (001) surface. Moreover, the analysis of adsorption energies and partial density of states (PDOS) suggests that a H2O‐CaO (001) surface (CaO (001) surface that has already adsorbed H2O) is more reactive than the clean CaO (001) surface for CO2 adsorption, which further supports the idea that the steam‐enhanced mechanism is an Eley–Rideal (E–R) mechanism, which means H2O is adsorbed on the CaO surface, and then CO2 is adsorbed. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2018
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11. Estimation of the carbonation reaction kinetic parameters for dilute methane and carbon dioxide conditions in a calcium looping process
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Savankumar Patel, James Sandford, Kalpit Shah, Priscilla Tremain, and Behdad Moghtaderi
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Flue gas ,Environmental Engineering ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Carbonation ,Environmental engineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Combustion ,Methane ,chemistry.chemical_compound ,020401 chemical engineering ,chemistry ,Chemical engineering ,Anaerobic oxidation of methane ,Carbon dioxide ,Environmental Chemistry ,0204 chemical engineering ,0210 nano-technology ,Waste Management and Disposal ,Chemical looping combustion ,Calcium looping ,General Environmental Science ,Water Science and Technology - Abstract
Experimental investigations were carried out to determine the intrinsic kinetic parameters of the carbonation reaction of limestone (CaCO3) in a calcium looping (CL) process for (1) dilute carbon dioxide conditions (1 vol % CO2 in air) and (2) dilute methane conditions (1 vol % CH4 in air). The random pore model (RPM) was applied to estimate the gas-solid heterogeneous kinetic parameters and further used to study the effects of bed temperature, fluidizing velocity and inventory size on carbon dioxide capture and methane combustion. Experiments were conducted in a single lab-scale bubbling fluidized bed reactor on calcined limestone at a range of temperatures (450–600°C) and inventory sizes (8–16 g). The activation energy determined for the carbonation reaction in dilute CO2 and dilute CH4 conditions were found to be 25.7 × 103 kJ/kmol and 22.3 × 103 kJ/kmol, respectively. These values were compared with the conventional calcium looping process (12–15% CO2 in flue gas). © 2017 American Institute of Chemical Engineers Environ Prog, 2017
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- 2017
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12. Carbonation kinetics of fly-ash-modified calcium-based sorbents for CO2 capture
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Lunbo Duan, Huichao Chen, Changsui Zhao, and Fang Wang
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Reaction mechanism ,Environmental Engineering ,Chromatography ,Chemistry ,Diffusion ,Carbonation ,Kinetics ,02 engineering and technology ,Activation energy ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Chemical engineering ,law ,Fly ash ,Environmental Chemistry ,Calcination ,0210 nano-technology ,Calcium looping ,0105 earth and related environmental sciences - Abstract
Calcium looping technology is one of the most promising technologies for CO2 capture. Nevertheless, one of the major problems for this technology is the rapid decay in CO2 capture performance of calcium-based sorbents during the calcination/carbonation cycles. It is essential to improve the sorbents’ CO2 capture capacity and maintain their long-term performance during the cycles, especially in a cost-effective and environmentally benign method for further development of the technology. Calcium-based sorbents modified with fly ash present great potential for enhancing CO2 capture capacity. Carbonation kinetics of the modified sorbents, an important factor for CO2 capture system design, is critical for exploring its application. The carbonation rate of the modified sorbents has been investigated and the main parameters such as activation energy and pre-exponential factor have been calculated. Logistic and Avrami fractional kinetics models show better fitting regression, as indicated with a high regression coefficient R2 of 0.987–0.999. The models well describe the CO2 carbonation kinetics behavior of the modified sorbents, since they have considered the multi-step reaction mechanisms including film diffusion, intra-particle diffusion, and the interaction with active sites, and have an acceptable average relative error between calculated and experimental data, for example 0.618–6.39% and 4.24–5.39% for the modified sorbents at chemical-controlled reaction and diffusion-controlled reaction, respectively. Activation energy and pre-exponential factor at chemical-controlled reaction are E1 = 15.019 kJ/mol, k01 = 5.940 mol/(m2s) and E2 = 12.252 kJ/mol, k02 = 3.195 mol/(m2s) for modified sorbents CaO/FA Hyd (50%AC) and CaO/PFA(cal)Hyd, respectively. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2017
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13. CaO-Based CO2 Sorbents Effectively Stabilized by Metal Oxides
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Muhammad Awais Naeem, Andac Armutlulu, Qasim Imtiaz, and Christoph R. Müller
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Sorbent ,Materials science ,Carbonation ,Inorganic chemistry ,Oxide ,Sintering ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Calcination ,Particle size ,Physical and Theoretical Chemistry ,0210 nano-technology ,Calcium oxide ,Calcium looping - Abstract
Calcium looping (i.e., CO2 capture by CaO) is a promising second-generation CO2 capture technology. CaO, derived from naturally occurring limestone, offers an inexpensive solution, but due to the harsh operating conditions of the process, limestone-derived sorbents undergo a rapid capacity decay induced by the sintering of CaCO3 . Here, we report a Pechini method to synthesize cyclically stable, CaO-based CO2 sorbents with a high CO2 uptake capacity. The sorbents synthesized feature compositional homogeneity in combination with a nanostructured and highly porous morphology. The presence of a single (Al2 O3 or Y2 O3 ) or bimetal oxide (Al2 O3 -Y2 O3 ) provides cyclic stability, except for MgO which undergoes a significant increase in its particle size with the cycle number. We also demonstrate a direct relationship between the CO2 uptake and the morphology of the synthesized sorbents. After 30 cycles of calcination and carbonation, the best performing sorbent, containing an equimolar mixture of Al2 O3 and Y2 O3 , exhibits a CO2 uptake capacity of 8.7 mmol CO2 g-1 sorbent, which is approximately 360 % higher than that of the reference limestone.
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- 2017
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14. Enhanced CO2 Capture Performance of Limestone by Industrial Waste Sludge
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Minghou Xu, Jian Sun, Yuandong Yang, Yingchao Hu, Wenqiang Liu, and Zijian Zhou
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Inert ,Sorbent ,Waste management ,General Chemical Engineering ,Sintering ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,Raw material ,Reuse ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,Industrial waste ,Metal framework ,Environmental science ,0210 nano-technology ,Calcium looping ,0105 earth and related environmental sciences - Abstract
Although inert supports have been proved effective to enhance CO2 capture performance of CaO sorbents, more commonly used supports are derived from expensive raw materials (such as nitrates and organometallic precursors). This work utilized cheap waste sludge from the steel plant, which is of a high daily output and has not received effective reuse, to promote the CO2 capture performance. The results showed that the sludge effectively promoted the performance of limestone. Homogeneously dispersed inert material of MgO, acting as the metal framework to resist sintering, was responsible for the enhanced performance. The introduction of waste sludge into the calcium looping could not only improve the sorbent performance, but also provide a potentially effective way to reuse the waste sludge.
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- 2017
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15. SO2 removal characteristics using waste CaO from calcium looping CO2 capture process
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Jingyu Ran, Li Zhang, Donglin He, Yan Shao, and Changlei Qin
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Pollution ,Engineering ,Environmental Engineering ,Waste management ,business.industry ,media_common.quotation_subject ,Dolomite ,Sorption ,02 engineering and technology ,Chemical industry ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,01 natural sciences ,Flue-gas desulfurization ,Scientific method ,Environmental Chemistry ,Particle size ,0210 nano-technology ,business ,Calcium looping ,0105 earth and related environmental sciences ,media_common - Abstract
Calcium looping (CaL) has been identified to be a valuable candidate for CO2 capture and has entered a stage of large-scale experiment and application. However, the serious loss-in-capacity problem will result in the production of a large amount of waste CaO, which not only increases the economic cost of the capture process, also generates a huge risk of secondary pollution. In this work, the waste CaO from CaL was first proposed to be used for SO2 removal by wet desulfurization and the SO2 sorption characteristics were comprehensively studied. Through experimental test and analysis, it is found that CaL-spent CaO derived from dolomite can achieve higher efficiency than that from the limestone in SO2 removal. The effect of CaL cycle on the SO2 removal performance is observed to be small when the cycle number is under 40. Beyond that, the SO2 removal capacity decreases quickly, which is thought to be due to the variation in slaking rate determined by the compromise between the surface area and pore size distribution of the material. Furthermore, sulfation performance of waste CaO is found to be superior with a particle size smaller than 0.4 mm. This work proves the feasibility of the utilization of CaL-spent CaO in wet SO2 removal, and could be beneficial for understanding the SO2 sorption characteristics of CaL-spent materials. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.
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- 2017
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16. Derivation of Kinetics and Design Parameters for a Carbonator Reactor in a Greenhouse Calcium Looping Process
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Elham Doroodchi, Behdad Moghtaderi, Mohammad Ramezani, Kalpit Shah, and Priscilla Tremain
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General Energy ,Waste management ,Chemistry ,020209 energy ,Scientific method ,Carbonation ,Kinetics ,0202 electrical engineering, electronic engineering, information engineering ,Greenhouse ,02 engineering and technology ,Calcium looping - Published
- 2017
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17. Investigation of Y 2 O 3 /MgO‐modified extrusion–spheronized CaO‐based pellets for high‐temperature CO 2 capture
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Jingyu Ran, Changlei Qin, Donglin He, Shuai Pi, and Zonghao Zhang
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Materials science ,Extrusion spheronization ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Metallurgy ,Pellets ,Extrusion ,Waste Management and Disposal ,Calcium looping - Published
- 2019
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18. Simulation of a calcium looping CO2 capture process for pressurized fluidized bed combustion
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Poupak Mehrani, Robin W. Hughes, Arturo Macchi, Edward J. Anthony, Robert T. Symonds, and Benoit Duhoux
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Materials science ,business.industry ,General Chemical Engineering ,Scientific method ,Fluidized bed combustion ,Process simulation ,pressurized FBC ,Process engineering ,business ,Carbon capture ,process simulation ,Calcium looping ,calcium looping - Abstract
The Canadian regulations on carbon dioxide emissions from power plants aim to lower the emissions from coal‐fired units down to those of natural gas combined cycle (NGCC) units. Since coal is significantly more carbon intensive than natural gas, coal‐fired plants must operate at higher net efficiencies and implement carbon capture to meet the new regulations. Calcium looping (CaL) is a promising post‐combustion carbon capture (PCC) technology that, unlike other capture processes, generates additional power. By capturing carbon dioxide at elevated temperatures, the energy penalty that carbon capture technologies inherently impose on power plant efficiencies is significantly reduced. In this work, the CO2 capture performance of a calcium‐based sorbent is determined via thermogravimetric analysis under relatively high carbonation and low calcination temperatures. The results are used in an aspenONE™ simulation of a CaL process applied to a pressurized fluidized bed combustion (PFBC) system at thermodynamic equilibrium. The combustion of both natural gas and coal are considered for sorbent calcination in the CaL process. A sensitivity analysis on several process parameters, including sorbent feed rate and carbonator operating pressure, is undertaken. The energy penalty associated with the capture process ranges from 6.8 –11.8 percentage points depending on fuel selection and operating conditions. The use of natural gas results in lower energy penalties and solids circulation rates, while operating the carbonator at 202 kPa(a) results in the lowest penalties and drops the solids circulations rates to below 1000 kg/s.
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- 2019
19. Natural Calcium-Based Sorbents Doped with Sea Salt for Cyclic CO2Capture
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Liqi Zhang, Haoran Ding, Zhou Dong, Cong Luo, Yongqing Xu, and Ying Zheng
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food.ingredient ,General Chemical Engineering ,Sea salt ,Doping ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Calcium ,021001 nanoscience & nanotechnology ,Industrial and Manufacturing Engineering ,chemistry.chemical_compound ,food ,Adsorption ,020401 chemical engineering ,chemistry ,Carbon dioxide ,Calcium Compounds ,0204 chemical engineering ,0210 nano-technology ,Calcium looping - Abstract
Calcium looping is used for post‐combustion carbon dioxide capture. A simple method was applied to modify calcium‐based sorbents for this purpose. The precursors were extremely cheap, readily available materials. Results showed that the CO 2 ‐capture capacity of sea‐salt‐doped limestone was 40 % higher than that of natural limestone sorbents.
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- 2017
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20. Mechanochemically Activated, Calcium Oxide-Based, Magnesium Oxide-Stabilized Carbon Dioxide Sorbents
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Marcin Broda, Javier Pérez-Ramírez, Davood Hosseini, Christoph R. Müller, Sharon Mitchell, and Alexey Kurlov
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Materials science ,General Chemical Engineering ,Carbonation ,Inorganic chemistry ,chemistry.chemical_element ,Sintering ,Context (language use) ,02 engineering and technology ,Calcium ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Drug Stability ,Environmental Chemistry ,General Materials Science ,Calcium oxide ,Calcium looping ,Mechanical Phenomena ,Magnesium ,Oxides ,Calcium Compounds ,Carbon Dioxide ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,General Energy ,chemistry ,Carbon dioxide ,Magnesium Oxide ,0210 nano-technology - Abstract
Carbon dioxide capture and storage (CCS) is a promising approach to reduce anthropogenic CO2 emissions and mitigate climate change. However, the costs associated with the capture of CO2 using the currently available technology, that is, amine scrubbing, are considered prohibitive. In this context, the so-called calcium looping process, which relies on the reversible carbonation of CaO, is an attractive alternative. The main disadvantage of naturally occurring CaO-based CO2 sorbents, such as limestone, is their rapid deactivation caused by thermal sintering. Here, we report a scalable route based on wet mechanochemical activation to prepare MgO-stabilized, CaO-based CO2 sorbents. We optimized the synthesis conditions through a fundamental understanding of the underlying stabilization mechanism, and the quantity of MgO required to stabilize CaO could be reduced to as little as 15 wt %. This allowed the preparation of CO2 sorbents that exceed the CO2 uptake of the reference limestone by 200 %.
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- 2016
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21. Energy Consumption for CO2Capture by means of the Calcium Looping Process: A Comparative Analysis using Limestone, Dolomite, and Steel Slag
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Ricardo Chacartegui, Jose Manuel Valverde, and C. Ortiz
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Thermogravimetric analysis ,Materials science ,020209 energy ,Carbonation ,Metallurgy ,Dolomite ,02 engineering and technology ,Combustion ,law.invention ,General Energy ,020401 chemical engineering ,law ,0202 electrical engineering, electronic engineering, information engineering ,Carbon capture and storage ,Calcination ,0204 chemical engineering ,Chemical looping combustion ,Calcium looping - Abstract
The calcium looping (CaL) process, based upon the dry carbonation/calcination of CaO/CaCO3, is at the center of a potentially low-cost, second-generation technology for CO2 capture. This manuscript analyzes the energy penalty that arises from the integration of the CaL process into a coal-fired power plant using cheap and abundantly available CaO precursors such as natural limestone, dolomite, and steel slag. Experimental results on their multicycle capture capacity behavior obtained from thermogravimetric analysis (TGA) at realistic CaL conditions for CO2 capture are used to this end. This work shows that the specific energy consumption for CO2 avoided (SPECCA) is reduced by using either dolomite or steel slag, whose carbonation kinetics in the diffusive phase are accelerated as compared to limestone. Thus, the use of dolomite as CaO precursor would yield a low SPECCA value of approximately 2 MJ kg−1 CO2 for a residence time of the solids in the carbonator of approximately 10 minutes, which is clearly below the SPECCA value usually reported for conventional amine-based CO2 capture systems.
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- 2016
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22. CO2 capture and attrition performance of competitive eco-friendly calcium-based pellets in fluidized bed
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Su, Chenglin, Duan, Lunbo, and Anthony, Edward J.
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attrition ,CaO‐based sorbent ,CO 2 capture ,spent bleaching clay regeneration ,calcium looping - Abstract
A system incorporating spent bleaching clay (SBC) into the calcium looping (CaL) process has been proposed. In this paper, prepared sorbents doped with regenerated SBC and cement were tested in a bubbling fluidized bed (BFB) to examine in detail their cyclic CO2 capture capacity and attrition properties. The results revealed that the cyclic CO2 capture capacity of pellets modified by pyrolyzed SBC and/or cement showed significantly better performance than limestone, which is consistent with the thermogravimetric analyzer (TGA) results. This is due to the improvement of pore structure and enhanced sintering resistance created by adding support materials to the sorbent. The elutriation rates of the composites prepared with pyrolyzed SBC and/or cement were consistently lower than for crushed limestone. Scanning electron microscopy (SEM) images indicated that the pellets possessed higher sphericity than limestone particles, thus reducing surface abrasion. Limestone exhibited a high attrition rate (diameter reduction rate) of 10.7 μm/cycle, which could be eliminated effectively by adding regenerated SBC and/or cement. ‘L‐5PC‐10CA’ (85% lime/5% pyrolyzed SBC/10% cement) exhibited an attrition rate of only 7.9 μm/cycle. Based on the analysis of breakage and probability density function (PDF) for particle size distribution, it appeared that pellets without cement experienced breakage (mostly chipping and disintegration) and surface abrasion, whereas ‘L‐10CA’ (90% lime/10% cement) and ‘L‐5PC‐10CA’ mainly suffered surface abrasion, combined with some chipping.
- Published
- 2018
23. The Role of Water on the Performance of Calcium Oxide-Based Sorbents for Carbon Dioxide Capture: A Review
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Bo Zhang, Zhongqing Yang, Mingnv Guo, and Li Zhang
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Sorbent ,Materials science ,Waste management ,Carbonation ,food and beverages ,complex mixtures ,law.invention ,chemistry.chemical_compound ,General Energy ,chemistry ,law ,Carbon dioxide ,Calcination ,Calcium oxide ,Water vapor ,Calcium looping - Abstract
A technology using calcium oxide (CaO)-based sorbents for CO2 capture has been identified to be the optimal candidate for capturing CO2 at high temperature. Realistic gases always contain water vapor and many other components, and it has been reported that these wet conditions have a non-negligible influence on the performance of the sorbent. This Review outlines the role of H2O during the CO2 capture process using CaO-based sorbents. The role of steam/H2O in sorbent reactivation, the effect of steam on carbonation and calcination, and the influence of steam when simultaneously existing in both carbonation and calcination stages are discussed. It is suggested that injection of steam in both carbonator and calciner is a good strategy to achieve better reactivity of the CaO-based sorbent for CO2 capture. The mechanisms of the effect of steam in carbonator and calciner on CO2 capture are also discussed. The Review concludes with future research directions.
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- 2014
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24. Cyclic CO2capture of carbide slag modified by pyroligneous acid in calcium looping cycles
- Author
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Changtian Liu, Yingjie Li, Shuimu Wu, and Rongyue Sun
- Subjects
Materials science ,Sorbent ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Carbonation ,Metallurgy ,Slag ,Carbide ,law.invention ,chemistry.chemical_compound ,chemistry ,Acetylene ,Pyroligneous acid ,law ,visual_art ,visual_art.visual_art_medium ,Calcination ,Waste Management and Disposal ,Calcium looping - Abstract
Carbide slag is a kind of industrial waste obtained in the production of acetylene that is the raw material of polyvinyl chloride in chlor-alkali plants. The carbide slag modified by pyroligneous acid was proposed as a CO2 sorbent at high temperature. The CO2 capture capacity of the carbide slag modified by pyroligneous acid in the calcium looping cycles was investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The modified carbide slag exhibits better CO2 capture capacity than the carbide slag. The modified carbide slag releases the organic substances whose combustion leads to a drop in CO2 capture capacity. The pre-calcination treatment of the modified carbide slag at 400 °C before the first calcination was employed to avoid the combustion of the organic substances. The pre-calcined modified carbide slag exhibits higher carbonation conversions, compared with the modified carbide slag without pre-calcination treatment. The pre-calcined modified carbide slag achieves higher carbonation conversions at 950 °C and shows larger surface area and pore volume than the modified carbide slag in the cycles. It indicates that combining the modification by pyroligneous acid with the pre-calcination treatment apparently improves cyclic CO2 capture capacity of the carbide slag in the multiple cycles. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
- Published
- 2014
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25. Synthesis of a Porous Nano-CaO/MgO-Based CO2Adsorbent
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Peiqiang Lan and Sufang Wu
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Materials science ,Magnesium ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Sorption ,General Chemistry ,Industrial and Manufacturing Engineering ,law.invention ,Adsorption ,chemistry ,Chemical engineering ,law ,Specific surface area ,Slurry ,Calcination ,Porosity ,Calcium looping - Abstract
A porous nano-CaO/MgO-based adsorbent was prepared using MgO as a support in order to increase the sorption capacity and durability. The magnesium sol prepared by reacting MgO slurry with citric acid was added to nano-CaCO3 slurry and the mixture was calcinated to obtain the nano-CaO/MgO-based adsorbent. The influence of MgO content on the structure and sorption performance of the resulting adsorbent was studied in detail. The pore radius and specific surface area of the adsorbent increased with higher MgO content. The adsorbent exhibited superior sorption performance during calcium looping and maintained a good durability at the calcination temperature, thus being an interesting candidate for future work.
- Published
- 2014
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26. Sulfation Rates of Particles in Calcium Looping Reactors
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Jose M. Cordero, Borja Arias, Juan Carlos Abanades, and Mónica Alonso
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Flue gas ,Sorbent ,Waste management ,Chemistry ,General Chemical Engineering ,Carbonation ,General Chemistry ,complex mixtures ,Industrial and Manufacturing Engineering ,law.invention ,Reaction rate ,Sulfation ,Chemical engineering ,law ,Particle ,Calcination ,Calcium looping - Abstract
The sulfation reaction rate of CaO particles in three reactors comprising a post-combustion calcium looping system is discussed: a combustion chamber generating flue gases, a carbonator reactor to capture CO2 and SO2, and an oxy-fired calciner to regenerate the CO2 sorbent. Due to its strong impact on the pore size distribution of CaO particles, the number of carbonation/calcination cycles arises as a new important variable to understand sulfation phenomena. Sulfation patterns change as a result of particle cycling, becoming more homogeneous with higher number of cycles. Experimental results from thermogravimetric tests demonstrate that high sulfation rates can be measured under all conditions tested, indicating that the calcium looping systems will be extremely efficient in SO2 capture.
- Published
- 2013
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27. Carbon capture in molten salts
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Espen Olsen and Viktorija Tomkute
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Flue gas ,Carbonation ,Inorganic chemistry ,Extraction (chemistry) ,Halide ,Chloride ,chemistry.chemical_compound ,General Energy ,chemistry ,Carbon dioxide ,medicine ,Molten salt ,Safety, Risk, Reliability and Quality ,Calcium looping ,medicine.drug - Abstract
Capture and storage of fossil carbon emitted to the atmosphere from anthropogenic sources has been identified as a key technology for keeping human-induced global warming below 2°C. Available technologies have not achieved widespread impact due to costs related to increased energy consumption and expensive, large process equipment. Here, we show how molten inorganic halide salt-based mixtures containing CaO may be utilized for selective capture and subsequent controlled release of carbon dioxide from diluted flue gases. Highly efficient absorption is demonstrated in a fluoride-based liquid, absorbing close to 100% of the CO2 from a simulated flue gas with an absorbing column height of only 10 cm. Greater than 90% carbonation with >80% regeneration to CaO was recorded. Excellent cyclability has been achieved with a chloride-based liquid with 60% carbonation and 100% regeneration to CaO during four cycles. The high efficiencies may enable extraction of CO2 from highly diluted gas mixtures.
- Published
- 2013
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28. The role of membranes in post-combustion CO2capture
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Patricia Luis and Bart Van der Bruggen
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Environmental Engineering ,Waste management ,business.industry ,Chemistry ,Post combustion ,Permeation ,Membrane technology ,Adsorption ,Membrane ,Chemical products ,Environmental Chemistry ,Absorption (chemistry) ,Process engineering ,business ,Calcium looping - Abstract
There are several technological options for post-combustion CO2 capture. Absorption with novel solvents, adsorption, conversion of CO2 into chemical products, calcium looping, and membrane technology are the main alternatives to the conventional absorption process based on amines. In this review, an overview of these technologies is presented and the role that membranes play is evaluated considering two approaches: (i) processes based on selective membranes (gas permeation and supported liquid membranes), and (ii) processes based on non-selective membranes (membrane contactors). The process performance demonstrated by recent research shows that membrane technology can fulfi ll the technical requirements for CO2 capture but a closer interaction with the industrial partners and membrane manufacturers is needed to implement this technology in the industry.
- Published
- 2013
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29. Ca(OH)2-Based Calcium Looping Process Development at The Ohio State University
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William Wang, Nihar Phalak, and Liang-Shih Fan
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Sorbent ,Waste management ,Chemistry ,business.industry ,Process development ,General Chemical Engineering ,chemistry.chemical_element ,General Chemistry ,Calcium ,Industrial and Manufacturing Engineering ,law.invention ,law ,Calcination ,Process engineering ,business ,Calcium looping - Abstract
The cyclic calcium oxide-calcium carbonate (CaO-CaCO3) process is a promising option for large-scale CO2 control. Important advantages include high-temperature operation, inexpensive sorbent feedstock, and high CO2 capture capacity of CaO. However, decreasing sorbent reactivity over multiple cycles, due to high-temperature sintering, presents a major challenge for further progress. The Ohio State University (OSU) has led the development of a novel three-step calcium looping (CaO-Ca(OH)2-CaCO3) process for post- and precombustion CO2 capture. An overview of OSU's work is provided, highlighting the differences in this approach when compared to competing efforts in this field.
- Published
- 2013
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30. Design and Experimental Investigation of Calcium Looping Process for 3-kWthand 1.9-MWthFacilities
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Cheng-Hsien Shen, Chin-Ming Huang, Jui-Yen Cheng, Wei-Cheng Chen, Liu Wan-Hsia, T.-W. Wen, Hsu Heng-Wen, Chen Wang, Chang Ming-Hui, and Shoung Ouyang
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Engineering ,Sorbent ,Waste management ,business.industry ,General Chemical Engineering ,General Chemistry ,Industrial and Manufacturing Engineering ,law.invention ,chemistry.chemical_compound ,Pilot plant ,chemistry ,Fluidized bed ,law ,Carbon capture and storage ,Calcination ,business ,Process engineering ,Calcium oxide ,Calcium looping ,Rotary kiln - Abstract
The calcium looping CO2 capture process using calcium oxide as a regenerable solid sorbent has been under development at the Industrial Technology Research Institute (ITRI) of Taiwan for several years. The 3-kWth test facility built at ITRI is mainly composed of a fluidized-bed carbonator and a rotary kiln calciner. The calcination efficiency, the CO2 capture efficiency, and operating stability were investigated. In addition, a cold model test facility has been constructed and a 1.9-MWth pilot plant designed by ITRI is currently being erected. The combination of calcium looping and cement manufacturing process reduces the cost of adsorbent and calcination energy consumption.
- Published
- 2013
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31. CaO-Based CO2Sorbents: From Fundamentals to the Development of New, Highly Effective Materials
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Agnieszka M. Kierzkowska, Christoph R. Müller, and Roberta Pacciani
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Sorbent ,Waste management ,business.industry ,General Chemical Engineering ,Fossil fuel ,Oxides ,Calcium Compounds ,Carbon Dioxide ,Absorption ,Nanostructures ,Kinetics ,Important research ,General Energy ,Electricity generation ,Greenhouse gas ,Thermodynamics ,Environmental Chemistry ,Environmental science ,General Materials Science ,business ,Calcium looping - Abstract
The enormous anthropogenic emission of the greenhouse gas CO2 is most likely the main reason for climate change. Considering the continuing and indeed growing utilisation of fossil fuels for electricity generation and transportation purposes, development and implementation of processes that avoid the associated emissions of CO2 are urgently needed. CO2 capture and storage, commonly termed CCS, would be a possible mid-term solution to reduce the emissions of CO2 into the atmosphere. However, the costs associated with the currently available CO2 capture technology, that is, amine scrubbing, are prohibitively high, thus making the development of new CO2 sorbents a highly important research challenge. Indeed, CaO, readily obtained through the calcination of naturally occurring limestone, has been proposed as an alternative CO2 sorbent that could substantially reduce the costs of CO2 capture. However, one of the major drawbacks of using CaO derived from natural sources is its rapidly decreasing CO2 uptake capacity with repeated carbonation-calcination reactions. Here, we review the current understanding of fundamental aspects of the cyclic carbonation-calcination reactions of CaO such as its reversibility and kinetics. Subsequently, recent attempts to develop synthetic, CaO-based sorbents that possess high and cyclically stable CO2 uptakes are presented.
- Published
- 2013
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32. Combined calcium looping and chemical looping combustion for post‐combustion carbon dioxide capture: process simulation and sensitivity analysis
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Dennis Y. Lu, Arturo Macchi, Edward J. Anthony, Benoit Duhoux, Robert T. Symonds, and Poupak Mehrani
- Subjects
Work (thermodynamics) ,Materials science ,Thermodynamic equilibrium ,02 engineering and technology ,010501 environmental sciences ,Combustion ,01 natural sciences ,chemistry.chemical_compound ,020401 chemical engineering ,chemical looping ,0204 chemical engineering ,Process simulation ,Calcium oxide ,Process engineering ,Calcium looping ,0105 earth and related environmental sciences ,calcium ,business.industry ,carbon storage ,process simulation ,General Energy ,chemistry ,Heat of combustion ,business ,Chemical looping combustion ,combustion - Abstract
In this work, a combined calcium looping and chemical looping combustion (CaL--CLC) technology is simulated at thermodynamic equilibrium conditions and the results in terms of efficiency, power production, and solids circulation rates are compared with the case of using CaL alone. In addition, a new solids looping configuration in the CaL--CLC process is proposed with the purpose of mitigating the loss of calcium oxide conversion after high cycle numbers. Simulations show an improved process efficiency of the CaL--CLC method compared with CaL alone (34.2 vs. 31.2 % higher heat value) and an increased power output (136 vs. 110 MWe additional power) due to the higher energy requirement to preheat the reactants. A sensitivity analysis of the process operating parameters highlights the particular importance of the temperature difference between reactors, which has a strong impact on the required mass of solids circulating in the loops. Finally, partial carbon dioxide capture scenarios are considered and indicate that lower capture levels are suitable to match regulation targets.
- Published
- 2016
33. ChemInform Abstract: The Calcium-Looping Technology for CO2Capture: On the Important Roles of Energy Integration and Sorbent Behavior
- Author
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Yolanda Lara, Ana Martínez, Antonio Perejón, Luis M. Romeo, Jose Manuel Valverde, and Pilar Lisbona
- Subjects
Energy demand ,Sorbent ,Chemistry ,business.industry ,Process (engineering) ,Carbonation ,General Medicine ,law.invention ,law ,Fluidized bed ,Energy integration ,Calcination ,Process engineering ,business ,Calcium looping - Abstract
The Calcium Looping (CaL) technology, based on the multicyclic carbonation/calcination of CaO in gas–solid fluidized bed reactors at high temperature, has emerged in the last years as a potentially low cost technology for CO2 capture. In this manuscript a critical review is made on the important roles of energy integration and sorbent behavior in the process efficiency. Firstly, the strategies proposed to reduce the energy demand by internal integration are discussed as well as process modifications aimed at optimizing the overall efficiency by means of external integration. The most important benefit of the high temperature CaL cycles is the possibility of using high temperature streams that could reduce significantly the energy penalty associated to CO2 capture. The application of the CaL technology in precombustion capture systems and energy integration, and the coupling of the CaL technology with other industrial processes are also described. In particular, the CaL technology has a significant potential to be a feasible CO2 capture system for cement plants. A precise knowledge of the multicyclic CO2 capture behavior of the sorbent at the CaL conditions to be expected in practice is of great relevance in order to predict a realistic capture efficiency and energy penalty from process simulations. The second part of this manuscript will be devoted to this issue. Particular emphasis is put on the behavior of natural limestone and dolomite, which would be the only practical choices for the technology to meet its main goal of reducing CO2 capture costs. Under CaL calcination conditions for CO2 capture (necessarily implying high CO2 concentration in the calciner), dolomite seems to be a better alternative to limestone as CaO precursor. The proposed techniques of recarbonation and thermal/mechanical pretreatments to reactivate the sorbent and accelerate calcination will be the final subjects of this review.
- Published
- 2016
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34. Sol-Gel-Derived, Calcium-Based, Copper-Functionalised CO2Sorbents for an Integrated Chemical Looping Combustion-Calcium Looping CO2Capture Process
- Author
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Christoph R. Müller and Agnieszka M. Kierzkowska
- Subjects
Magnesium ,Carbonation ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Calcium ,Redox ,law.invention ,chemistry.chemical_compound ,Calcium carbonate ,chemistry ,law ,Calcination ,Chemical looping combustion ,Calcium looping - Abstract
Using a sol–gel technique, new copper-functionalised, calcium-based CO2 sorbents were developed to integrate chemical looping combustion into the calcium looping scheme. In this process, the exothermic reduction of copper oxide with methane, carbon monoxide or hydrogen is used to provide the heat required to calcine (regenerate) calcium carbonate. The materials contained CuO and CaO in a molar ratio of either 1.3:1 or 3.3:1, were supported on Al2O3, MgO or MgAl2O4 and were characterised by means of X-ray diffraction, N2 physisorption, scanning electron microscopy and temperature-programmed reduction. All materials, independent of the precursors and support material used, possessed excellent cyclic oxygen-carrying capacities. However, it was found that the presence of magnesium in the support stabilised the CO2 uptake and minimised carbon deposition. CuCa-MgAl-1.3:1 was the material that possessed the highest CO2 uptake of 0.13 g gmaterial−1 after 15 cycles of repeated carbonation/calcination–redox reactions.
- Published
- 2012
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35. Morphological Changes of Pure Micro- and Nano-Sized CaCO3 during a Calcium Looping Cycle for CO2 Capture
- Author
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Cong Luo, Qiuwen Shen, Zhixiang Feng, Chuguang Zheng, Ning Ding, and Ying Zheng
- Subjects
Sorbent ,Materials science ,Chemical engineering ,General Chemical Engineering ,Carbonation ,Sintering ,Mineralogy ,General Chemistry ,Crystallite ,Grain boundary migration ,Nano sized ,Industrial and Manufacturing Engineering ,Calcium looping - Abstract
Cyclic CO capture using CaO-based sorbents derived from commercial pure micro-sized CaCO and nano-sized CaCO was investigated, focusing on the different characteristics of carbonation conversions, carbonation rates, surface areas, pore volumes, morphological changes, and microstrains of two sorbents during high-temperature reactions. The results indicated that the CaO-based sorbent derived from nano-sized CaCO (NC-CaO) provided higher carbonation conversions and carbonation rates than the CaO-based sorbent derived from micro-sized CaCO (MC-CaO) in the cyclic CO capture reactions. Furthermore, NC-CaO retained its fast carbonation rate at the beginning of each cycle for several tens of seconds. In contrast, the carbonation rate of MC-CaO diminished with an increase in the cycle number. Unfortunately, NC-CaO sintered more easily. Its grains, which were composed of numerous spherical nanocrystallites, suffered from dramatic morphological changes during high-temperature reactions. A mechanism of grain boundary migration was employed to explain the sintering of CaO-based sorbent. The smaller crystallites were more susceptible to be merged by the bigger crystallites during high-temperature reactions.
- Published
- 2012
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36. Thermodynamic Simulation of CO2 Capture for an IGCC Power Plant using the Calcium Looping Cycle
- Author
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Chuanwen Zhao, Yingjie Li, and Qiangqiang Ren
- Subjects
Materials science ,Waste management ,Power station ,General Chemical Engineering ,Integrated gasification combined cycle ,General Chemistry ,Thermodynamic simulation ,Industrial and Manufacturing Engineering ,Calcium looping - Published
- 2011
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37. Reduction of greenhouse gas emissions by integration of cement plants, power plants, and CO2 capture systems
- Author
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Ana Martínez, Luis M. Romeo, David Catalina, Pilar Lisbona, and Yolanda Lara
- Subjects
Engineering ,Environmental Engineering ,Waste management ,Primary energy ,Power station ,business.industry ,Process flow diagram ,Chemical industry ,Clinker (cement) ,Greenhouse gas ,Industrial symbiosis ,Environmental Chemistry ,business ,Calcium looping - Abstract
Cement plants and power plants are two of the most significant sources of greenhouse gases emissions. Many CO2 reduction options have been proposed in literature for both sectors. They are mainly focused on CO2 capture in power plants, but, in the short-term, industrial processes are going to play an important role in achieving this objective. In particular, one of the disadvantages in cement plants is that CO2 has two sources: fuel combustion and lime calcination. For this reason, proposed solutions could partially reduce a limited quantity of emissions. The sector is forced to use CO2 capture systems for further reductions. Preliminary results about the implementation of post-combustion and oxyfuel combustion systems for CO2 capture show low energetic penalties and important emissions reduction. Nevertheless, a detailed analysis, not only of CO2 emissions, but of raw materials and its disposal, primary energy and waste energy, could give optimum results from an environmental, energetic, and economic perspective. The combination/integration by industrial symbiosis of a power plant, a cement plant and a CO2 capture system is proposed in this work. Calcium-looping is chosen as the most suitable CO2 capture option for this application. The re-use of waste CaO coming from CO2 capture in the cement plant, and the utilization of waste energy from a clinker cooling and capture system to produce additional power are the main advantages of this proposal. Process flow diagrams and heat and mass balances are calculated and presented in this work. Results show a low value of the CO2 avoided cost, 12.4 €/t, that is smaller than in any other combination of power plant with capture system or cement plant plus capture system, making this proposal economically very attractive. Moreover, an important amount of CO2 emissions is avoided - 94% - due to the energetic efficiency augmentation, the reduction of raw and decarbonizated materials, and the CO2 capture system. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
- Published
- 2011
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38. Ca looping technology: current status, developments and future directions
- Author
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Edward J. Anthony
- Subjects
Flue gas ,Engineering ,Environmental Engineering ,Lead (geology) ,Waste management ,business.industry ,Environmental Chemistry ,Chemical industry ,Current period ,Biochemical engineering ,Current (fluid) ,business ,Calcium looping - Abstract
Calcium looping technology is a promising new technique for high-temperature scrubbing of CO2 from flue gas and syngases. Current economic projections suggest it might be able to capture CO2 at costs of ∼$20/ton of avoided CO2. Nonetheless there are questions about the long-term behavior of natural sorbents in such systems, and there is substantial R&D being done on this technology worldwide to answer questions about whether the performance of natural sorbents can be improved, or whether it would be better to use synthetic ones. The current period is particularly interesting as the first pilot plants and demonstration units capable of operating continuously are now coming on stream, and if successful these will lead to large-scale industrial demonstrations of the technology in the next 10 to 15 years. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
- Published
- 2011
- Full Text
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39. The reversibility of the reaction CaCO3 ⇄ CaO+CO2
- Author
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Ronald Barker
- Subjects
chemistry.chemical_compound ,Calcium carbonate ,chemistry ,Diffusion ,Carbon dioxide ,Inorganic chemistry ,Oxide ,Carbonate ,Reactivity (chemistry) ,Decomposition ,Calcium looping - Abstract
The reversibility of the reaction CaCO3 ⇌ CaO+CO2 has been examined through a large number of cycles (up to 40), mainly at 866 °C. The decomposition to the oxide is always 100% but the reactivity of the oxide so formed to carbon dioxide falls off markedly after a rapid initial reaction. There is a large increase in surface area on going from the non-porous calcium carbonate to the oxide and this is due to the formation of pores, mostly very small (< 4 nm). The fast component of the back reaction is a surface reaction and the subsequent slow reaction is controlled by the slow diffusion of carbon dioxide through the newly formed carbonate layer. The reversibility of the reaction decreases with the number of cycles, rapidly at first and then more slowly: the first effect is probably due to loss of pore volume in the oxide and the second to sintering of the carbonate.
- Published
- 2007
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40. Capture of CO2 from combustion gases in a fluidized bed of CaO
- Author
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Diego Alvarez, Dennis Y. Lu, Edward J. Anthony, J. Carlos Abanades, and Carlos Salvador
- Subjects
Flue gas ,Environmental Engineering ,Sorbent ,Waste management ,Chemistry ,General Chemical Engineering ,Carbonation ,Nuclear engineering ,Combustion ,Fluidized bed ,Fluidized bed combustion ,Calcium looping ,Chemical looping combustion ,Biotechnology - Abstract
Experiments in a pilot-scale fluidized-bed reactor have been carried out to investigate the carbonation reaction of CaO, as a potential method for CO2 capture from combustion flue gases at high-temperatures. Results show that CO2 capture efficiencies are very high, while there is a sufficient fraction of CaO in the bed reacting in the fast reaction regime. The total capture capacity of the bed decays with the number of carbonation-calcination cycles. The experimental CO2 concentration profiles measured inside the bed during the fast reaction period are interpreted with the KL fluid bed model, by supplying information on sorbent deactivation from laboratory tests. It is concluded that a fluidized bed of CaO can be a suitable reactor to achieve very effective CO2 capture efficiencies from a combustion flue gas. © 2004 American Institute of Chemical Engineers AIChE J, 50:1614–1622, 2004
- Published
- 2004
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41. ChemInform Abstract: The Calcium Looping Cycle for CO2Capture from Power Generation, Cement Manufacture and Hydrogen Production
- Author
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John Blamey, Mohamad J. Al-Jeboori, Charles Dean, Paul S. Fennell, and Nick Florin
- Subjects
Cement ,Flue gas ,Electricity generation ,Sorbent ,Power station ,business.industry ,Chemistry ,Fossil fuel ,General Medicine ,Process engineering ,business ,Calcium looping ,Hydrogen production - Abstract
Calcium looping is a CO 2 capture scheme using solid CaO-based sorbents to remove CO 2 from flue gases, e.g., from a power plant, producing a concentrated stream of CO 2 (∼95%) suitable for storage. The scheme exploits the reversible gas–solid reaction between CO 2 and CaO(s) to form CaCO 3 (s). Calcium looping has a number of advantages compared to closer-to-market capture schemes, including: the use of circulating fluidised bed reactors—a mature technology at large scale; sorbent derived from cheap, abundant and environmentally benign limestone and dolomite precursors; and the relatively small efficiency penalty that it imposes on the power/industrial process (i.e., estimated at 6–8 percentage points, compared to 9.5–12.5 from amine-based post-combustion capture). A further advantage is the synergy with cement manufacture, which potentially allows for decarbonisation of both cement manufacture and power production. In addition, a number of advanced applications offer the potential for significant cost reductions in the production of hydrogen from fossil fuels coupled with CO 2 capture. The range of applications of calcium looping are discussed here, including the progress made towards demonstrating this technology as a viable post-combustion capture technology using small-pilot scale rigs, and the early progress towards a 2 MW scale demonstrator.
- Published
- 2012
- Full Text
- View/download PDF
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