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1.
Lingmei Yang Pengmei Lv Zhongming Wang Zhenhong Yuan Wen Luo Huiwen Li 《International Journal of Green Energy》2017,14(9):784-791
A series of heterogeneous KF/CaO catalysts modified with transition metals (lanthanum, cerium, and zirconium) were prepared via wet impregnation method and applied to the trsansesterification process of waste cooking oil (WCO) as feedstock with methanol to biodiesel production. The structure, performance of the solid catalysts was characterized by X-ray diffraction (XRD), temperature programmed desorption of CO2 (CO2-TPD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The effect of methanol/oil molar ratio, 1reaction time, reaction temperature, catalyst amount, and stability was investigated. The results showed that 10 wt% of lanthanum, cerium, and zirconium improved the catalytic activity of KF/CaO catalyst. The maximum catalytic activity using the lanthanum doping of 10wt% on KF/CaO catalyst was reached 98.7% under the optimal reaction condition of methanol/oil molar ratio of 12:1, reaction for 1 h at reaction temperature of 65°C, and 4% (wt/wt oil) catalyst amount. In addition, the FAME yield of KF/CaO/La catalyst remained higher than 95% after 10 cycles. The promotional effect of lanthanum doping could be attributed to the enhancement of the basicity strength of KF/CaO catalyst and block the leach of Ca2+ in the transesterification reaction. 相似文献
2.
Ye Wu Xiaoping Chen Chuanwen Zhao 《International Journal of Greenhouse Gas Control》2011,5(5):1184-1189
With thermogravimetric apparatus (TGA), X-ray diffraction (XRD) and barium sulfate gravimetric methods, the carbonation reactivities of K2CO3 and K2CO3/Al2O3 in the simulated flue gases with SO2 are investigated and the reaction equations are inferred. Results show that there are KHCO3 and K2SO3 generated. The generation K2SO3 reduces the utilization ratio of the sorbent. H2O may accelerates the sulfation reaction of AR K2CO3 as K4H2(CO3)3·1.5H2O is generated in the reaction among K2CO3, SO2 and H2O. K2SO3 is directly generated from sulfation reaction of K2CO3/Al2O3, because there are K2CO3·1.5H2O and K2SO3 generated in the reaction among K2CO3/Al2O3, SO2 and H2O. K2CO3·1.5H2O does not react with SO2, and K2CO3·1.5H2O/Al2O3 reacts with SO2 slowly. Compare with the reaction process without H2O pretreatment, the reaction rates of KAl30 increased after H2O pretreatment and the failure ratio is about a half of that without H2O pretreatment. So, K2CO3/Al2O3 shows good carbonation and anti-sulfation characteristic after H2O pretreatment. 相似文献
3.
Yuki Kano Toru Sato Jun Kita Shinichiro Hirabayashi Shigeru Tabeta 《International Journal of Greenhouse Gas Control》2009,3(5):617-625
A numerical study was conducted to predict pCO2 change in the ocean on a continental shelf by the leakage of CO2, which is originally stored in the aquifer under the seabed, in the case that a large fault connects the CO2 reservoir and the seabed by an earthquake or other diastrophism. The leakage rate was set to be 6.025 × 10−4 kg/m2/sec from 2 m × 100 m fault band, which corresponds to 3800 t-CO2/year, referring to the monitored seepage rate from an existing EOR field. The target space in this study was limited to the ocean above the seabed, the depth of which was 200 or 500 m. The computational domain was idealistically rectangular with the seabed fault-band perpendicular to the uniform flow. The CO2 takes a form of bubbles or droplets, depending on the depth of water, and their behaviour and dissolution were numerically simulated during their rise in seawater flow. The advection–diffusion of dissolved CO2 was also simulated. As a result, it was suggested that the leaked CO2 droplets/bubbles all dissolve in the seawater before spouting up to the atmosphere, and that the increase in pCO2 in the seawater was smaller than 500 μ atm. 相似文献
4.
An environmentally benign, simple, and efficient process has been developed for biodiesel production from waste olive oil in the presence of a catalytic amount of TiO2 nanoparticles at 120°C with a conversion of 91.2% within 4 h. The present method affords nontoxic and noncorrosive medium, high yield of biodiesel, clean reaction, and simple experimental and isolation procedures. The catalyst can be recycled by simple filtration and reused without any significant reduction in its activity. 相似文献
5.
J.P. Jakobsen G. Tangen
. Nordb M.J. Mlnvik 《International Journal of Greenhouse Gas Control》2008,2(4):439-447
The paper presents a methodology for CO2 chain analysis with particular focus on the impact of technology development on the total system economy. The methodology includes the whole CO2 chain; CO2 source, CO2 capture, transport and storage in aquifers or in oil reservoirs for enhanced oil recovery. It aims at supporting the identification of feasible solutions and assisting the selection of the most cost-effective options for carbon capture and storage. To demonstrate the applicability of the methodology a case study has been carried out to illustrate the possible impact of technology improvements and market development. The case study confirms that the CO2-quota price to a large extent influence the project economy and dominates over potential technology improvements. To be economic feasible, the studied chains injecting the CO2 in oil reservoirs for increased oil production require a CO2-quota price in the range of 20–27 €/tonne CO2, depending on the technology breakthrough. For the chains based on CO2 storage in saline aquifers, the corresponding CO2-quota price varies up to about 40 €/tonne CO2. 相似文献
6.
Global warming is a result of increasing anthropogenic CO2 emissions, and the consequences will be dramatic climate changes if no action is taken. One of the main global challenges in the years to come is therefore to reduce the CO2 emissions.Increasing energy efficiency and a transition to renewable energy as the major energy source can reduce CO2 emissions, but such measures can only lead to significant emission reductions in the long-term. Carbon capture and storage (CCS) is a promising technological option for reducing CO2 emissions on a shorter time scale.A model to calculate the CO2 capture potential has been developed, and it is estimated that 25 billion tonnes CO2 can be captured and stored within the EU by 2050. Globally, 236 billion tonnes CO2 can be captured and stored by 2050. The calculations indicate that wide implementation of CCS can reduce CO2 emissions by 54% in the EU and 33% globally in 2050 compared to emission levels today.Such a reduction in emissions is not sufficient to stabilize the climate. Therefore, the strategy to achieve the necessary CO2 emissions reductions must be a combination of (1) increasing energy efficiency, (2) switching from fossil fuel to renewable energy sources, and (3) wide implementation of CCS. 相似文献
7.
Hailong Li Øivind Wilhelmsen Yuexia Lv Weilong Wang Jinyue Yan 《International Journal of Greenhouse Gas Control》2011,5(5):1119-1139
Accurate experimental data on the thermo-physical properties of CO2-mixtures are pre-requisites for development of more accurate models and hence, more precise design of CO2 capture and storage (CCS) processes. A literature survey was conducted on both the available experimental data and the theoretical models associated with the transport properties of CO2-mixtures within the operation windows of CCS. Gaps were identified between the available knowledge and requirements of the system design and operation. For the experimental gas-phase measurements, there are no available data about any transport properties of CO2/H2S, CO2/COS and CO2/NH3; and except for CO2/H2O(/NaCl) and CO2/amine/H2O mixtures, there are no available measurements regarding the transport properties of any liquid-phase mixtures. In the prediction of gas-phase viscosities using Chapman–Enskog theory, deviations are typically <2% at atmospheric pressure and moderate temperatures. The deviations increase with increasing temperatures and pressures. Using both the Rigorous Kinetic Theory (RKT) and empirical models in the prediction of gas-phase thermal conductivities, typical deviations are 2.2–9%. Comparison of popular empirical models for estimation of gas-phase diffusion coefficients with newer experimental data for CO2/H2O shows deviations of up to 20%. For many mixtures relevant for CCS, the diffusion coefficient models based on the RKT show predictions within the experimental uncertainty. Typical reported deviations of the CO2/H2O system using empirical models are below 3% for the viscosity and the thermal conductivity and between 5 and 20% for the diffusion coefficients. The research community knows little about the effect of other impurities in liquid CO2 than water, and this is an important area to focus in future work. 相似文献
8.
Virenkumar Shah Daniel Broseta Gerard Mouronval Franois Montel 《International Journal of Greenhouse Gas Control》2008,2(4):594
Acid gas geological disposal is a promising process to reduce CO2 atmospheric emissions and an environment-friendly and economic alternative to the transformation of H2S into sulphur by the Claus process. Acid gas confinement in geological formations is to a large extent controlled by the capillary properties of the water/acid–gas/caprock system, because a significant fraction of the injected gas rises buoyantly and accumulates beneath the caprock. These properties include the water/acid gas interfacial tension (IFT), to which the so-called capillary entry pressure of the gas in the water-saturated caprock is proportional. In this paper we present the first ever systematic water/acid gas IFT measurements carried out by the pendant drop technique under geological storage conditions. We performed IFT measurements for water/H2S systems over a large range of pressure (up to P = 15 MPa) and temperature (up to T = 120 °C). Water/H2S IFT decreases with increasing P and levels off at around 9–10 mN/m at high T (≥70 °C) and P (>12 MPa). The latter values are around 30–40% of water/CO2 IFTs, and around 20% of water/CH4 IFTs at similar T and P conditions. The IFT between water and a CO2 + H2S mixture at T = 77 °C and P > 7.5 MPa is observed to be approximately equal to the molar average IFT of the water/CO2 and water/H2S binary mixtures. Thus, when the H2S content in the stored acid gas increases the capillary entry pressure decreases, together with the maximum height of acid gas column and potential storage capacity of a given geological formation. Hence, considerable attention should be exercised when refilling with a H2S-rich acid gas a depleted gas reservoir, or a depleted oil reservoir with a gas cap: in the case of hydrocarbon reservoirs that were initially (i.e., at the time of their discovery) close to capillary leakage, acid gas leakage through the caprock will inevitably occur if the refilling pressure approaches the initial reservoir pressure. 相似文献
9.
食物生产不仅依赖水资源,同时产生大量二氧化碳排放,这种资源环境影响存在于食物系统整个产业链。为促进食物系统节水降碳,本文构建了包含5大类共23种具体食物部门的混合生命周期评价模型,对各类食物系统的完全水资源消耗和二氧化碳排放进行了核算与比较。结果表明:(1)不同食物的水资源消耗和二氧化碳排放差异明显,动物性食物的平均水资源消耗和二氧化碳排放强度分别为植物性食物的1.9~15.0倍和1.9~2.7倍;(2)食物系统直接和间接水资源消耗占比较为接近,但二氧化碳排放主要源自上游产业链的间接排放,占比高达80.9%;(3)食物系统间接水资源消耗主要来自农业部门,而间接碳排放主要来自电力生产和供应业、基础化工原料制造业、非金属矿产品行业和交通运输业;(4)从营养元素供给看,动物性食物提供蛋白质和脂肪的资源环境影响高于植物性食物,蔬菜和主食分别在提供维生素C和碳水化合物上具有最小的环境成本。基于本文结果,食物系统节水应主要提高生产环节用水效率,而降碳则主要依靠上游产业减排,特别是发电和化肥生产等行业的协同节水减碳潜力。同时,本文结果也可为未来基于环境影响制定膳食指南提供数据支撑。 相似文献
10.
Semere Solomon Michael Carpenter Todd Allyn Flach 《International Journal of Greenhouse Gas Control》2008,2(4):502
Enhanced oil recovery (EOR) through CO2 flooding has been practiced on a commercial basis for the last 35 years and continues today at several sites, currently injecting in total over 30 million tons of CO2 annually. This practice is currently exclusively for economic gain, but can potentially contribute to the reduction of emissions of greenhouse gases provided it is implemented on a large scale. Optimal operations in distributing CO2 to CO2-EOR or enhanced gas recovery (EGR) projects (referred to here collectively as CO2-EHR) on a large scale and long time span imply that intermediate storage of CO2 in geological formations may be a key component. Intermediate storage is defined as the storage of CO2 in geological media for a limited time span such that the CO2 can be sufficiently reproduced for later use in CO2-EHR. This paper investigates the technical aspects, key individual parameters and possibilities of intermediate storage of CO2 in geological formations aiming at large scale implementation of carbon dioxide capture and storage (CCS) for deep emission reduction. The main parameters are thus the depth of injection and density, CO2 flow and transport processes, storage mechanisms, reservoir heterogeneity, the presence of impurities, the type of the reservoirs and the duration of intermediate storage. Structural traps with no flow of formation water combined with proper injection planning such as gas-phase injection favour intermediate storage in deep saline aquifers. In depleted oil and gas fields, high permeability, homogeneous reservoirs with structural traps (e.g. anticlinal structures) are good candidates for intermediate CO2 storage. Intuitively, depleted natural gas reservoirs can be potential candidates for intermediate storage of carbon dioxide due to similarity in storage characteristics. 相似文献
11.
Zhongqing Yang Li Zhang Jin Peng Mingnv Guo 《International Journal of Green Energy》2015,12(10):1046-1053
The gasification reaction of Nantong inferior coal was investigated in a laboratory fixed-bed reactor under CO2 and O2/H2O atmospheres. The effects of the bed temperature and inlet-gas concentration on the yields of CO, H2, and CH4 were studied. The effects of coal ash and particle size on the fixed-carbon conversion were also investigated, and kinetic analysis was conducted with a homogeneous model. The product-gas-heating value and fixed-carbon conversion increased when the temperature was increased from 950 °C to 1100 °C under CO2 atmosphere. When the inlet-CO2 concentration was increased from 50 to 100 vol.%, the low heating value of the product gas and carbon conversion ratio slightly increased. During the gasification of inferior coal under the O2/H2O atmosphere, the CO concentration increased rapidly with increasing temperature. The H2 and CH4 concentrations increased initially and then decreased. The maximum gas heating value of 7934 kJ/m3 was obtained under the O2 concentration of 70 vol.% at a bed temperature of 1050 °C. The cold-gas efficiency increased with increasing temperature and became 40.6% and 86.4% at 1100 °C under the CO2 and O2/H2O atmospheres, respectively. The gasification reaction of the Nantong inferior coal strongly depended on the content of inherent inorganic matter. The gasification rates for both the CO2 and O2/H2O atmospheres were independent of the particle size. The activation energy for the CO2 and O2/H2O gasification reactions were 137 and 81 kJ/mol, respectively. The gasification reactions of the Nantong coal, which was performed under two different atmospheres, were compared and the reaction activity of the gasification reaction under CO2 atmosphere was found to be much lower than that under the O2/H2O atmosphere. 相似文献
12.
Michael Zettlitzer Fabian Moeller Daria Morozova Peter Lokay Hilke Würdemann the COSINK Group 《International Journal of Greenhouse Gas Control》2010,4(6):952-959
The onshore CO2-storage site Ketzin consists of one CO2-injection well and two observation wells. Hydraulic tests revealed permeabilities between 50 and 100 mD for the sandstone rock units. The designated injection well Ktzi 201 showed similar production permeability. After installation of the CO2-injection string, an injection test with water yielded a significantly lower injectivity of 0.002 m3/d kPa, while the observation wells showed an injection permeability in the same range as the productivity. Several possible reasons for the severe decline in injectivity are discussed. Acidification of the reservoir interval, injection at high wellhead pressure, controlled mini-fractures and back-production of the well are discussed to remove the plugging material to re-establish the required injectivity of the well. It has been decided to perform a nitrogen lift and analyse the back-produced fluids. Initially during the lift, the back-produced fluids were dark-black. Chemical and XRD analyses proved that the black solids consisted mainly of iron sulphide. Sulphate-reducing bacteria (SRB) were detected in fluid samples with up to 106 cells/ml by fluorescent in situ hybridisation (FISH) indicating that the formation of iron sulphide was caused by bacterial activity. Organic compounds within the drilling mud and other technical fluids were likely left during the well completion process, thus providing the energy source for strong proliferation of bacteria. During the lift, the fraction of SRB in the whole bacterial community decreased from approximately 32% in downhole samples to less than 5%. The lift of Ktzi 201 succeeded in the full restoration of the well productivity and injectivity. Additionally, the likely energy source of the SRB was largely removed by the lifting, thus ensuring the long-term preservation of the injectivity. 相似文献
13.
M. Olivares-Marín S. García C. Pevida M.S. Wong M. Maroto-Valer 《Journal of environmental management》2011
Adsorption is one of the most promising technologies for reducing CO2 emissions and at present several different types of sorbents are being investigated. The use of sorbents obtained from low-cost and abundant precursors (i.e. solid wastes) appears an attractive strategy to adopt because it will contribute to a reduction not only in operational costs but also in the amount of waste that is dumped and burned in landfills every year. Following on from previous studies by the authors, in this work several carbon-based adsorbents were developed from different carpet wastes (pre-consumer and post-consumer wastes) by chemical activation with KOH at various activation temperatures (600–900 °C) and KOH:char impregnation ratios (0.5:1 to 4:1). The prepared materials were characterised by chemical analysis and gas adsorption (N2, −196 °C; CO2, 0 °C), and tested for CO2 adsorption at temperatures of 25 and 100 °C. It was found that both the type of precursor and the conditions of activation (i.e. impregnation ratios, and activation temperatures), had a huge influence on the microporosity of the resultant samples and their CO2 capture capacities. The carbon-based adsorbent that presented the maximum CO2 capture capacities at 25 and 100 °C (13.8 wt.% and 3.1 wt.%, respectively), was prepared from a pre-consumer carpet waste and was activated at 700 °C using a KOH:char impregnation ratio of 1:1. This sample showed the highest narrow microporosity volume (0.47 cm3 g−1), thus confirming that only pores of less than 1 nm are effective for CO2 adsorption at atmospheric pressure. 相似文献
14.
This research article demonstrates biodiesel synthesis through the methanolysis of the oily contents (4.02 ± 0.27% w/w on dried basis) of Dictyota dichotoma collected from the coast of Hawksbay, Pakistan. The metal oxides (CaO, MgO, ZnO, and TiO2) used as nanocatalysts were refluxed (5% K2SO4), calcinated (850 °C) and characterized by Atomic Force Microscopy (AFM) which produced 93.2% w/w FAME (biodiesel) at relatively mild condition (5% catalyst, 65 °C, 3 h, 18:1 molar ratio) using CaO. Whereas, MgO, ZnO, and TiO2 produced 92.4%, 72.5%, and 31.8% w/w FAME, respectively at elevated condition (225 °C). Thus, CaO was considered to be the best catalyst among the others. This tri-phase reaction require continuous fast mixing and the yield depends on the reaction parameters like catalyst amount, temperature, reaction time and molar ratio (methanol: oil). The reusability of these heterogeneous catalysts simplified the purification step, reduced the waste generation and make the final product technically and economically viable. 相似文献
15.
Monitoring of the microbial community composition in saline aquifers during CO2 storage by fluorescence in situ hybridisation 总被引:1,自引:0,他引:1
Daria Morozova Maren Wandrey Mashal Alawi Martin Zimmer Andrea Vieth Michael Zettlitzer Hilke Würdemann the COSINK Group 《International Journal of Greenhouse Gas Control》2010,4(6):981-989
This study reveals the first analyses of the composition and activity of the microbial community of a saline CO2 storage aquifer. Microbial monitoring during CO2 injection has been reported. By using fluorescence in situ hybridisation (FISH), we have shown that the microbial community was strongly influenced by the CO2 injection. Before CO2 arrival, up to 6 × 106 cells ml−1 were detected by DAPI staining at a depth of 647 m below the surface. The microbial community was dominated by the domain Bacteria that represented approximately 60% to 90% of the total cell number, with Proteobacteria and Firmicutes as the most abundant phyla comprising up to 47% and 45% of the entire population, respectively. Both the total cell counts as well as the counts of the specific physiological groups revealed quantitative and qualitative changes after CO2 arrival. Our study revealed temporal outcompetition of sulphate-reducing bacteria by methanogenic archaea. In addition, an enhanced activity of the microbial population after five months CO2 storage indicated that the bacterial community was able to adapt to the extreme conditions of the deep biosphere and to the extreme changes of these atypical conditions. 相似文献
16.
Hilke Würdemann Fabian Mller Michael Kühn Wolfgang Heidug Niels Peter Christensen Günter Borm Frank R. Schilling the COSINK Group 《International Journal of Greenhouse Gas Control》2010,4(6):938-951
The CO2SINK pilot project at Ketzin is aimed at a better understanding of geological CO2 storage operation in a saline aquifer. The reservoir consists of fluvial deposits with average permeability ranging between 50 and 100 mDarcy. The main focus of CO2SINK is developing and testing of monitoring and verification technologies. All wells, one for injection and two for observation, are equipped with smart casings (sensors behind casing, facing the rocks) containing a Distributed Temperature Sensing (DTS) and electrodes for Electrical Resistivity Tomography (ERT). The in-hole Gas Membrane Sensors (GMS) observed the arrival of tracers and CO2 with high temporal resolution. Geophysical monitoring includes Moving Source Profiling (MSP), Vertical Seismic Profiling (VSP), crosshole, star and 4-D seismic experiments. Numerical models are benchmarked via the monitoring results indicating a sufficient match between observation and prediction, at least for the arrival of CO2 at the first observation well. Downhole samples of brine showed changes in the fluid composition and biocenosis. First monitoring results indicate anisotropic flow of CO2 coinciding with the “on-time” arrival of CO2 at observation well one (Ktzi 200) and the later arrival at observation well two (Ktzi 202). A risk assessment was performed prior to the start of injection. After one year of operations about 18,000 t of CO2 were injected safely. 相似文献
17.
Yemane Wolde-Rufael Eyob Mulat Weldemeskel 《International Journal of Green Energy》2020,17(10):568-582
ABSTRACT The aim of this paper is to investigate the relationship between environmental policy stringency and CO2 emissions in BRIICTS (Brazil, Russia, India, Indonesia, China, Turkey and South Africa) for the period 1993–2014 after controlling for renewable energy, fossil energy, oil prices and income. We believe that this is the first attempt to use the recently OECD-developed environmental policy stringency index to test the effectiveness of environmental stringency policy in reducing CO2 emission in these countries. Applying the Panel Pooled Mean Group Autoregressive Distributive Lag (PMG-ARDL) estimator, we found an inverted U–shaped relationship between environmental policy stringency and CO2 emissions. This suggests that initially strict stringent environmental policy does not lead to improvements in the environment but after a certain level or a threshold point, environmental stringency policy leads to improvement in environmental quality. Renewable energy consumption was negatively related to CO2 emissions while fossil energy consumption and real oil prices and income were positively and significantly related to CO2. Our findings suggest that strengthening the stringency of environmental policies and promoting renewable energy are effective ways of preventing environmental degradation in BRIICTS countries. 相似文献
18.
The goal of this paper is to find methodologies for removing a selection of impurities (H2O, O2, Ar, N2, SOx and NOx) from CO2 present in the flue gas of two oxy-combustion power plants fired with either natural gas (467 MW) or pulverized fuel (596 MW). The resulting purified stream, containing mainly CO2, is assumed to be stored in an aquifer or utilized for enhanced oil recovery (EOR) purposes. Focus has been given to power cycle efficiency i.e.: work and heat requirements for the purification process, CO2 purity and recovery factor (kg of CO2 that is sent to storage per kg of CO2 in the flue gas). Two different methodologies (here called Case I and Case II) for flue gas purification have been developed, both based on phase separation using simple flash units (Case I) or a distillation column (Case II). In both cases purified flue gas is liquefied and its pressure brought to 110 atm prior to storage.Case I: A simple flue gas separation takes place by means of two flash units integrated in the CO2 compression process. Heat in the process is removed by evaporating the purified liquid CO2 streams coming out from both flashes. Case I shows a good performance when dealing with flue gases with low concentration of impurities. CO2 fraction after purification is over 96% with a CO2 recovery factor of 96.2% for the NG-fired flue gas and 88.1% for the PF-fired flue gas. Impurities removal together with flue gas compression and liquefaction reduces power plant output of 4.8% for the NG-fired flue gas and 11.6% for the PF-fired flue gas. The total amount of work requirement per kg stored CO2 is 453 kJ for the NG-fired flue gas and 586 kJ for the PF-fired flue gas.Case II: Impurities are removed from the flue gas in a distillation column. Two refrigeration loops (ethane and propane) have been used in order to partially liquefy the flue gas and for heat removal from a partial condenser. Case II can remove higher amounts of impurities than Case I. CO2 purity prior to storage is over 99%; CO2 recovery factor is somewhat lower than in Case I: 95.4% for the NG-fired flue gas and 86.9% for the PF-fired flue gas, reduction in the power plant output is similar to Case I.Due to the lower CO2 recovery factor the total amount of work per kg stored CO2 is somewhat higher for Case II: 457 kJ for the NG-fired flue gas and 603 kJ for the PF-fired flue gas. 相似文献
19.
CO2 transportation for carbon capture and storage: Sublimation of carbon dioxide from a dry ice bank
Alberto Mazzoldi Tim Hill Jeremy J. Colls 《International Journal of Greenhouse Gas Control》2008,2(2):210-218
Climate change is being caused by greenhouse gases such as carbon dioxide (CO2). Carbon capture and storage (CCS) is of interest to the scientific community as one way of achieving significant global reductions of atmospheric CO2 emissions in the medium term. CO2 would be captured from large stationary sources such as power plants and transported via pipelines under high pressure conditions to underground storage. If a downward leakage from a surface transportation system module occurs, the CO2 would undergo a large temperature reduction and form a bank of “dry ice” on the ground surface; the sublimation of the gas from this bank represents an area source term for subsequent atmospheric dispersion, with an emission rate dependent on the energy balance at the bank surface. Gaseous CO2 is denser than air and tends to remain close to the surface; it is an asphyxiant, a cerebral vasodilator and at high concentrations causes rapid circulatory insufficiency leading to coma and death. Hence a subliming bank of dry ice represents safety hazard. A model is presented for evaluating the energy balance and sublimation rate at the surface of a solid frozen CO2 bank under different environmental conditions. The results suggest that subliming gas behaves as a proper dense gas (i.e. it remains close to the ground surface) only for low ambient wind speeds. 相似文献
20.
Veith Becker Anssi Myrttinen Philipp Blum Robert van Geldern Johannes A.C. Barth 《International Journal of Greenhouse Gas Control》2011,5(5):1250-1258
Stable carbon isotopes are important tools to assess potential storage sites for CO2, as they allow the quantification of ionic trapping via isotope mass balances. In deep geological formations high p/T conditions need to be considered, because CO2 dissolution, equilibrium constants and isotope fractionation of dissolved inorganic carbon (DIC) depend on temperature, pressure and solute composition. After reviewing different approaches to account for these dependencies, an expanded scheme is presented for speciation and carbon isotope fractionation of DIC and dissolution of CaCO3 for pCO2 up to 100 bar, pH down to 3 and temperatures of up to 200 °C. The scheme evaluates the influence of respective parameters on isotope ratios during CO2 sequestration. The pCO2 and pH are the dominant controlling factors in the DIC/δ13C/pH system. The fugacity of CO2 has major impact on DIC concentrations at temperatures below 100 °C at high pCO2. Temperature dependency of activities and equilibrium dominates at temperatures above 100 °C. Isotope ratios of DIC are expected to be about 1–2‰ more depleted in 13C compared to the free CO2 at pCO2 values above 10 bar. This depletion is controlled by carbon isotope fractionation between CO2 and H2CO3* which is the dominant species of DIC at the resulting pH below 5. 相似文献