Separation of CO2 from Flue Gas by High Reactivity Calcium Based Sorbents PDF Download
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Author: Himanshu Gupta
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 7
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Author: Himanshu Gupta
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 7
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Author: Danny Man-Leung Wong
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 220
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Abstract: Greenhouse gas emissions into the atmosphere have become an issue of concern with the increase in global population and demand for energy. In response to the demand for carbon emissions control, The Ohio State University has developed a novel high temperature multi-pollutant capture process that simultaneously captures carbon dioxide (CO2) and sulfur dioxide (SO2) from fossil fuels combustion flue gas streams. The multi- cyclic Carbonation Calcination Reaction (CCR) process utilizes a calcium-based sorbent in a high temperature reaction (carbonation) to capture the CO2 from the flue gas stream and releases a pure stream of CO2 that can be sequestered in the subsequent calcination reaction. The overall success of the technology depends on the development and optimization of the carbonation and calcination processes to create an integrated, cost and energy efficient process for carbon capture. The development of the CCR technology was further advanced from bench-scale research to an integrated, continuous, sub-pilot scale demonstration. Single-pass carbonation studies demonstrated high CO2 and SO2 removals using commercial calcium hydroxide as the sorbent in an entrained bed reactor. The high inherent pore volume of the commercial calcium hydroxide sorbent resulted in its demonstration of over 4 times the CO2 removal than commercial pulverized lime under similar process conditions. Bench-scale studies of the calcium carbonate (CaCO3) calcination reaction were conducted in the presence of steam and CO2 to effectively regenerate the spent CaCO3 sorbent in a manner suited for a carbon capture system. CaCO3 calcination in the presence of steam in the reactor lowers the partial pressure of CO2 such that complete calcination can be achieved at temperatures of 7500C and greater with significantly reduced calcination residence times. The resultant product CaO surface morphology is comparable to those achieved in calcination conditions of 100% CO2 despite known sintering effects of water vapor on the ionic structure of CaO.
Author:
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Category :
Languages : en
Pages : 2
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Author:
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ISBN:
Category :
Languages : en
Pages :
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In chapter 1, the studies focused on the development of novel sorbents for reducing the carbon dioxide emissions at high temperatures. Our studies focused on cesium doped CaO sorbents with respect to other major flue gas compounds in a wide temperature range. The thermo-gravimetric analysis of sorbents with loadings of CaO doped on 20 wt% cesium demonstrated high CO2 sorption uptakes (up to 66 wt% CO2/sorbent). It is remarkable to note that zero adsorption affinity for N2, O2, H2O and NO at temperatures as high as 600 C was observed. For water vapor and nitrogen oxide we observed a positive effect for CO2 adsorption. In the presence of steam, the CO2 adsorption increased to the highest adsorption capacity of 77 wt% CO2/sorbent. In the presence of nitrogen oxide, the final CO2 uptake remained same, but the rate of adsorption was higher at the initial stages (10%) than the case where no nitrogen oxide was fed. In chapter 2, Ca(NO3)2 · 4H2O, CaO, Ca(OH)2, CaCO3, and Ca(CH3COO)2 · H2O were used as precursors for synthesis of CaO sorbents on this work. The sorbents prepared from calcium acetate (CaAc2-CaO) resulted in the best uptake characteristics for CO2. It possessed higher BET surface area and higher pore volume than the other sorbents. According to SEM images, this sorbent shows 'fluffy' structure, which probably contributes to its high surface area and pore volume. When temperatures were between 550 and 800 C, this sorbent could be carbonated almost completely. Moreover, the carbonation progressed dominantly at the initial short period. Under numerous adsorption-desorption cycles, the CaAc2-CaO demonstrated the best reversibility, even under the existence of 10 vol % water vapor. In a 27 cyclic running, the sorbent sustained fairly high carbonation conversion of 62%. Pore size distributions indicate that their pore volume decreased when experimental cycles went on. Silica was doped on the CaAc2-CaO in various weight percentages, but the resultant sorbent did not exhibit better performance under cyclic operation than those without dopant. In chapter 3, the Calcium-based carbon dioxide sorbents were made in the gas phase by flame spray pyrolysis (FSP) and compared to the ones made by standard high temperature calcination (HTC) of selected calcium precursors. The FSP-made sorbents were solid nanostructured particles having twice as large specific surface area (40-60 m2/g) as the HTC-made sorbents (i.e. from calcium acetate monohydrate). All FSP-made sorbents showed high capacity for CO2 uptake at high temperatures (773-1073 K) while the HTC-made ones from calcium acetate monohydrate (CaAc2 · H2O) demonstrated the best performance for CO2 uptake among all HTC-made sorbents. At carbonation temperatures less than 773 K, FSP-made sorbents demonstrated better performance for CO2 uptake than all HTC-made sorbents. Above that, both FSP-made, and HTC-made sorbents from CaAc2 · H2O exhibited comparable carbonation rates and maximum conversion. In multiple carbonation/decarbonation cycles, FSP-made sorbents demonstrated stable, reversible and high CO2 uptake capacity sustaining maximum molar conversion at about 50% even after 60 such cycles indicating their potential for CO2 uptake. In chapter 4 we investigated the performance of CaO sorbents with dopant by flame spray pyrolysis at higher temperature. The results show that the sorbent with zirconia gave best performance among sorbents having different dopants. The one having Zr to Ca of 3:10 by molar gave stable performance. The calcium conversion around 64% conversion during 102-cycle operations at 973 K. When carbonation was performance at 823 K, the Zr/Ca sorbent (3:10) exhibited stable performance of 56% by calcium molar conversion, or 27% by sorbent weight, both of which are less than those at 973 K as expected. In chapter 5 we investigated the performance of CaO sorbents by flame spray pyrolysis at higher temperature with much shorter duration period. Stable high conversions were attained after 40 cycles The results show that the sorbent could reach high CO2 capture capacity, be completely regenerated in short time and be quite stable even at these severe conditions. Several studies were devoted to identify sorbents which could effectively capture CO2 while survive in SO2 atmosphere. From the group of sorbents we checked, a couple of sorbents showed very promising behavior, namely CO2 uptakes higher than 60% (wt/wt sorbent) while they acquired higher than 95% of their original activity/performance characteristics in a short period of time.
Author: Bartev Boghos Sakadjian
Publisher:
ISBN:
Category :
Languages : en
Pages : 228
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Author: Luca Di Felice
Publisher: Elsevier Inc. Chapters
ISBN: 0128082402
Category : Science
Languages : en
Pages : 46
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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This research effort is designed to investigate the technical feasibility of a high-temperature, high-pressure process for the bulk separation of CO2 from coal-derived gases. The two-year contract was awarded in September 1989. This report describes the research effort and results obtained during the first year of the effort. The overall project consists of 6 tasks, four of which were active during year 01. Tasks 1 and 2 were completed during the year while activity in Tasks 3 and 6 will carry over into year 02. Tasks 4 and 5 will be initiated during year 02. Three primary objectives were met in Task 1. A literature search on the calcination-carbonation reactions of CO2 with calcium-based sorbents was completed. A high temperature, high pressure (HTHP) electrobalance reactor suitable for studying the calcination and carbonation reactions was constructed. This reactor system is now fully operable and we are routinely collecting kinetics data at temperatures in the range of 550-900°C and pressures of 1 to 15 atm. Samples of nine candidate calcium-based sorbents were acquired and tested. These samples were subjected to reaction screening tests as part of Task 2. As a result of these screening tests, chemically pure calcium carbonate, chemically pure calcium acetate, and the commercial dolomite were selected for more detailed kinetic testing. In Task 3, the HTHP electrobalance reactor is being used to study the calcination-carbonation behavior of the three base sorbents as a function of calcination temperature, carbonation temperature, carbonation pressure, and CO2 concentration.
Author: Amoolya Dattatraya Lalsare
Publisher:
ISBN:
Category :
Languages : en
Pages : 67
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Calcium looping is a sorbent based chemical looping process that uses calcium oxide or similar calcium sorbent precursors for pre-/post-combustion carbon dioxide capture. Extensive study of this process at the Ohio State University has led to the development of two variants of this process: Carbonation-calcination reaction (CCR) process for post-combustion carbon capture in electricity generation and calcium looping process (CLP) for pre-combustion carbon capture in hydrogen production and electricity generation. CCR is a cyclic post-combustion carbon capture process, demonstrated at a 120 KWth scale at OSU. This demonstration achieved more than 90% carbon dioxide removal and over 99% sulfur dioxide (SO2) removal. It has been shown through process simulations that CCR process induces less energy penalty than the conventional amine/oxy-combustion based carbon dioxide capture technologies. This process involves carbonation-calcination-steam hydration of calcium sorbents. Steam hydration is a reactivation step which mitigates the effect of sintering of sorbents during calcination, regenerates the sorbent surface, and retains carbon capture capacity over a large number of cycles. High pressure steam reactivation of calcium sorbents was investigated and the dependence of hydration rate on steam pressure is obtained. Higher steam partial pressure allows for higher temperatures (500-550oC) to get higher hydration conversions. The reaction being highly exothermic (-109 kJ/mol), high temperature gives high quality heat which can be used elsewhere in the process. Reaction kinetics of steam hydration for four different limestone based sorbents was studied using high pressure thermogravimetric analysis. Elevated pressures (1-3.5 atm) and high temperature (500-530oC) were used in this study. Steam hydration of PG Graymont limestone sorbent experimentally showed second order w.r.t steam pressure driving force (PH2O – P*H2O). Rate constants for each operating conditions were calculated and activation energy of the reaction was computed from these calculations. The activation energy obtained from this study is 5.18 KJ/mol. Nitrogen physisorption studies were performed for characterization of the sorbents and their reactivity was compared via the steam hydration studies in the TGA at 500oC and PH2O 1.5 atm. CaO sorbent derived after hydration shows the highest surface area and pore volume, which is more than 6-10 times that of the sorbent derived by calcination of CaCO3. This study is a strong indication that hydration with water/steam regenerates the sorbent morphology, in process reactivating the sorbents with high porosity. It is believed, however, that initial particle size has little or no bearing on the reactivation process or sorbent reactivity in the multi-cyclic studies as hydration causes particle breakage. This study is significant in regard to the post-combustion and pre-combustion carbon capture calcium looping processes developed at OSU as the hydration temperature would be comparable to the carbonator temperature as it is expected to make the processes economically viable. There exists a trade-off however for the steam pressure to be used for hydration. Very high steam pressure would incur high compression costs and affect the energy penalty of the process. This could deter the compensating effect of heat recovered from the hydrator and in turn make the process more energy intensive. This study is limits the pressure to 4-5 times the atmospheric pressure and still obtain higher conversions.
Author: Frank C. Schora
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 296
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Book Description
This research effort is designed to investigate the technical feasibility of a high-temperature, high-pressure process for the bulk separation of CO2 from coal-derived gases. The two-year contract was awarded in September 1989. This report describes the research effort and results obtained during the first year of the effort. The overall project consists of 6 tasks, four of which were active during year 01. Tasks 1 and 2 were completed during the year while activity in Tasks 3 and 6 will carry over into year 02. Tasks 4 and 5 will be initiated during year 02. Three primary objectives were met in Task 1. A literature search on the calcination-carbonation reactions of CO2 with calcium-based sorbents was completed. A high temperature, high pressure (HTHP) electrobalance reactor suitable for studying the calcination and carbonation reactions was constructed. This reactor system is now fully operable and we are routinely collecting kinetics data at temperatures in the range of 550-900°C and pressures of 1 to 15 atm. Samples of nine candidate calcium-based sorbents were acquired and tested. These samples were subjected to reaction screening tests as part of Task 2. As a result of these screening tests, chemically pure calcium carbonate, chemically pure calcium acetate, and the commercial dolomite were selected for more detailed kinetic testing. In Task 3, the HTHP electrobalance reactor is being used to study the calcination-carbonation behavior of the three base sorbents as a function of calcination temperature, carbonation temperature, carbonation pressure, and CO2 concentration.
