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Abstract: In-situ CO2 capture in coal utilization captures CO2 during coal combustion or gasification such as Oxygen fuel combustion or Chemical looping coal gasification processes. Japan coal energy center (JCOAL) have proposed a chemical looping coal gasification method. This method utilizes a chemical looping with the calcium cycle, in which CaO (or Ca(OH)2) captures CO2 during coal gasification to form CaCO3 and release heat for gasification to produce hydrogen in one gasifier. This paper introduces the current developing status of the method, mainly including the experimental examination of the transition of sorbent particle size distribution, ash and sulfur concentration of materials at several locations of gasification and calcination system for the process. As results it is shown that, the product gases from the chemical looping coal gasification only contained nearly 80% H2 with 20% CH4 with dry base. It was also found that coal ash and sulfur concentrated highly in the process of calcination after cyclone. And the plant cold gas efficiency which should be affected by ash separation was also analyzed. If it is possible, separate and remove ash and sulfur by applying devices like filter or/and cyclone separator, the plant coal gas efficiency may raise 2 points than that in the previous study in which a part of recycled sorbent was rejected without separation. As an application of the chemical looping coal gasification, exergy regeneration type IGFC power generation was proposed. Exhaust heat of FC can be used for reforming of CH4 which produced by coal gasification. This system was analyzed by use AspenPlus. The result shown that, hydrogen cold gas efficiency was about 10% higher than the cold gas efficiency of the chemical looping coal gasification. [Copyright &y& Elsevier]

Abstract: One method for reducing CO2, the green house gas emissions is to capture CO2 before it releases into the atmosphere and then sequestrate it. Active lime (main component, CaO) can be used to capture CO2 in the exhaust gas or in the reactor from fossil fuels utilization effectively. That is calcium oxide (CaO) absorbs CO2 to yield calcium carbonate (CaCO3) (Eq.(1)), then the CaCO3 is thermally decomposed to CaO again and release nearly pure CO2 (Eq. (2)) for sequestration. To obtain a nearly pure CO2 stream from CaCO3 decomposition, the heat for decomposing CaCO3 can be supplied by combusting fossil fuels, such as coal and natural gas, in a calciner with oxygen fuel combustion. The oxygen diluted by CO2 (CO2 cycle) or H2O (steam cycle), in order to obtain near pure CO2 stream from CaCO3 decomposition. In our previous studie s4-6, it was clarified that calcinations of limestone (main component, CaCO3) in a fluidized bed calciner can be performed in CO2 cycle atmosphere when the bed temperature was raised above 1293 K, whereas with 60% steam cycle in atmosphere, limestone can be decomposed at comparatively lower temperature, such as 1173 K. The decomposition conversions of the limestone were about 95% and 98%, in CO2 cycle and in steam cycle atmospheres, respectively. Reducing the calcinations temperature of limestone was helpful to produce more than 30% active CaO as shown in previous stud y4-6. In this study, the energy of CaCO3 calcination process by H2O (steam) cycle was analyzed and compared with CaCO3 calcination process by CO2 cycle. For process calculations, the mass and energy flows were calculated iteratively, based on the input and output balances, until err [(input–output)/input] was <0.01. Analysis showed that, although H2O (steam) cycle calcination had calcination energy more about 3.6% than CO2 cycle due to water evaporation latent heat loss, however, the calcination energy per active CaO was lowest for H2O (steam) cycle. [Copyright &y& Elsevier]

Abstract: In-situ CO2 capture in coal utilization captures CO2 during coal combustion or gasification such as Oxygen fuel combustion or HyPr-RING. coal gasification processes. Regarding Oxufuel combustion, Callide Oxyfuel Project has been being conducted as the world first project to apply the technology to an existing power plant, Callide A Power Station #4 unit (30MWe) with injection of captured CO2 into the underground. This is a Japan-Australia collaboration project and JCOAL participates in it as a supporting collaborator. JCOAL also proposed a novel coal gasification method-,HyPr-RING (Hydrogen Production by Reaction-Integrated Novel Gasification). HyPr-RING method utilizes a chemical looping with the calcium cycle, in which CaO (or Ca(OH)2) captures CO2 during coal gasification completely to form CaCO3 and release heat for gasification to produce near pure hydrogen in one gasifier. This paper introduces the current developing status of the HyPr-RING method, mainly including the experimental examination of the transition of sorbent particle size distribution, ash and sulfur concentration of materials at several locations of gasification and calcination system for the HyPr-RING process. And the plant cold gas efficiency which should be affected by ash separation was also analyzed. As the results, it was found that coal ash and sulfur concentrated highly in the process of calcination after cyclone. If it is possible, separate and remove ash and sulfur by applying devices like filter or/and cyclone separator, the plant coal gas efficiency may raise 2 points than that in the previous study in which a part of recycled sorbent was rejected without separation. One method for reducing CO2, the green house gas emissions is to capture CO2 before it releases into the atmosphere and then sequestrate it. Active lime (main component, CaO) can be used to capture CO2 in the exhaust gas or in the reactor from fossil fuels utilization effectively. That is calcium oxide (CaO) absorbs CO2 to yield calcium carbonate (CaCO3) (Eq.(1)), then the CaCO3 is thermally decomposed to CaO again and release nearly pure CO2 (Eq. (2)) for sequestration. To obtain a nearly pure CO2 stream from CaCO3 decomposition, the heat for decomposing CaCO3 can be supplied by combusting fossil fuels, such as coal and natural gas, in a calciner with oxygen fuel combustion. The oxygen diluted by CO2 (CO2 cycle) or H2O (steam cycle), in order to obtain near pure CO2 stream from CaCO3 decomposition. In our previous studies4−6, it was clarified that calcinations of limestone (main component, CaCO3) in a fluidized bed calciner can be performed in CO2 cycle atmosphere when the bed temperature was raised above 1293 K, whereas with 60% steam cycle in atmosphere, limestone can be decomposed at comparatively lower temperature, such as 1173 K. The decomposition conversions of the limestone were about 95% and 98%, in CO2 cycle and in steam cycle atmospheres, respectively. Reducing the calcinations temperature of limestone was helpful to produce more than 30% active CaO as shown in previous study4−6. In this study, the energy of CaCO3 calcination process by H2O (steam) cycle was analyzed and compared with CaCO3 calcination process by CO2 cycle. For process calculations, the mass and energy flows were calculated iteratively, based on the input and output balances, until err [(input-output)/input] was <0.01. Analysis showed that, although H2O (steam) cycle calcination had calcination energy more about 3.6% than CO2 cycle due to water evaporation latent heat loss, however, the calcination energy per active CaO was lowest for H2O (steam) cycle. [Copyright &y& Elsevier]

Abstract: In this study, the decomposition conditions of limestone particles (0.25–0.50mm) for CO2 capture in a steam dilution atmosphere (20–100% steam in CO2) were investigated by using a continuously operating fluidized bed reactor. The results show that the decomposition conversion of limestone increased with the steam dilution percentage in the CO2 supply gas. At a bed temperature of 920°C, the conversions were 72% without steam dilution and 98% with 60% steam dilution. The conversion was 99% with 100% steam dilution at 850°C of the bed temperature. Steam dilution can decrease not only the decomposition temperature of limestone, but also the residence time required for nearly complete decomposition of CaCO3. The hydration and carbonation reactivities of the CaO produced were also tested and the results show that both the reactivities increased with the steam dilution percentage for decomposing limestone. [Copyright &y& Elsevier]

Abstract: Hydrocarbon can be gasified with steam into fuel gas, including CO, CO2, H2, CH4, etc. For H2 production, it is necessary to separate the other gases from hydrogen. In this study, hydrogen production by removal of carbon oxides during hydrocarbon gasification with CaO and other metal oxides was examined theoretically and experimentally. It was experimentally confirmed that when the hydrocarbon, water, and Ca(OH)2 were set in a micro-autoclave at a temperature of 973K and a pressure of 25MPa, the only gas products were hydrogen along with a small amount of methane. CO was converted to CO2, and CO2 was absorbed by Ca(OH)2 to form CaCO3 completely. CaOSiO2 can absorb CO2 to form CaCO3 under the same experimental conditions. Others such as MgO, SnO, and Fe2O3 were found to be unsuitable sorbents for CO2 absorption in the gasifier at high temperature. By calcination, CaCO3 can reform to CaO. Because the chemical energy contained in CaO can be released during hydrocarbon gasification, H2 production efficiency as high as 70–80% can be expected. [Copyright &y& Elsevier]

Hydrogen generation during the reaction of a coal/CaO mixture with high pressure steam was investigated using a flow-type reactor. Coal, CaO and CO reactions with steam, and CO2 absorption by Ca(OH)2 or CaO occurred simultaneously in the experiment. It was found that H2 was the primary resultant gas, comprising about 85% of the reaction products. CO2 was fixed into CaCO3 and CO was completely converted to H2. Pyrolysis of the coal/CaO mixture carried out in N2 was also examined. The pyrolysis gases were compared with gases produced by general coal pyrolysis. While general coal pyrolysis produced about 14.7% H2, 50.5% CH4, 12.0% CO and 12.0% CO2, the gases produced from coal/CaO mixture pyrolysis were 84.8% H2, 9.6% CH4, 1.6% CO2 and 1.1% CO. [Copyright &y& Elsevier]

The gas-phase reaction dynamics for the C(1D) + H2(D2) → CH(D) + H(D) is investigated on a new ab initio potential energy surface (PES). The initial state-specified integral cross section and rate constant are obtained using the Chebyshev real wave packet method; the low-lying vibrational energy levels are also calculated on this new PES using Lanczos algorithm. The vibrational energy levels agree well with the experimental data and are superior to Bussery-Honvault-Honvault-Launay [B. Bussery-Honvault, P. Honvault, and J.-M. Launay, J. Chem. Phys. 115, 10701 (2001)] surfaces' results. The reaction probabilities display oscillatory structure due to the numerous long-lived resonances supported by the deep potential well. The rate constants show nearly temperature independence at the range of 100 K-350 K. [ABSTRACT FROM AUTHOR]

The gas-phase reaction dynamics for the C((1)D) + H2(D2) → CH(D) + H(D) is investigated on a new ab initio potential energy surface (PES). The initial state-specified integral cross section and rate constant are obtained using the Chebyshev real wave packet method; the low-lying vibrational energy levels are also calculated on this new PES using Lanczos algorithm. The vibrational energy levels agree well with the experimental data and are superior to Bussery-Honvault-Honvault-Launay [B. Bussery-Honvault, P. Honvault, and J.-M. Launay, J. Chem. Phys. 115, 10701 (2001)] surfaces' results. The reaction probabilities display oscillatory structure due to the numerous long-lived resonances supported by the deep potential well. The rate constants show nearly temperature independence at the range of 100 K-350 K.