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1.
Life cycle analysis (LCA) methodology was used to perform a quantitative, comparative analysis and rating of the construction and operation of a wind energy plant. For this case study, the Glacier Hills Wind Park (90 1.8-MW turbines in south-central Wisconsin) was evaluated. Significant environmental and economic benefits are often advertised with the installation of new wind energy facilities, although independent and comprehensive LCA and sustainable energy science are typically not implemented. Hence, a quantitative demonstration with LCA methodology of the life cycle emissions and environmental impact, from construction through operations, can greatly assist in highlighting significant areas of energy consumption and emissions during manufacturing, transportation, and construction of a wind farm. Results portray the amount of greenhouse gas emissions and energy consumption/generation over the life cycle of the wind park. Transportation of large components from overseas led to the consumption of considerable quantities of fossil fuel, responsible for up to 22 % of the total greenhouse gas emissions due to transportation. The energy payback ratio (25.5), energy payback time (12.3 months) and the total grams of equivalent CO2(eq) per kWh of energy (16.9) produced were calculated over the life time of this onshore wind farm.  相似文献   

2.
Deep (> ～800 m) saline water-bearing formations in the United States have substantial pore volume that is targeted for storage of carbon dioxide (CO2) and the associated saline water can be extracted to increase CO2 storage efficiency, manage pressure build up, and create a new water source that, once treated, can be used for power-plant cooling or other purposes. Extraction, treatment and disposal costs of saline formation water to meet added water demands from CO2 capture and storage (CCS) are discussed. This underutilized water source may be important in meeting new water demand associated with CCS. For a representative natural gas combined-cycle (NGCC) power plant, simultaneous extraction of brine from the storage formation could provide enough water to meet all CCS-related cooling demands for 177 out of the 185 (96 %) saline formations analyzed in this study. Calculated total cost of water extraction, treatment and disposal is less than 4.00 US Dollars (USD) m?3 for 93 % of the 185 formations considered. In 90 % of 185 formations, treated water costs are less than 10.00 USD tonne?1 of CO2 injected. On average, this represents approximately 6 % of the total CO2 capture and injection costs for the NGCC scenario.  相似文献   

3.
This paper explores China’s strategies for addressing climate change on the industrial level. Focusing on six energy-intensive industries, this paper applies gray relational analysis theory to the affecting factors to CO2 emissions of each industry after calculating each industry’s CO2 emissions during 2001–2010. Further research based on GM(1, 1) model is conducted to forecast the trend of the factors, the energy consumption and each industry’s CO2 emissions during the 12th Five-Year Plan period. As a breakthrough in previous conclusions, energy consumption structure was divided into the respective proportion of coal, oil, natural gas and electricity in the primary energy consumption, with which industrial output and energy intensity are combined to analyze each of their impacts on the energy-intensive industries. It turns out that all the factors’ impacts on emissions of the six major energy-intensive industries are significant, despite their differentiated extents. It is worth noting that, contrary to previous findings, industrial output is not the leading affecting factor to CO2 emissions of the energy-intensive industries compared with the proportion of coal and electricity in the primary energy consumption. The GM(1, 1) forecast results of energy consumption and CO2 emissions by the end of 2015 show that coal and electricity will remain a large proportion in primary energy consumption. This research may shed some light on China’s adjustment of energy structure under the pressure of addressing climate change and hence provide decision support for the acceleration of renewable energy utilization in the industrial departments.  相似文献   

4.
The United States is one of the world's leaders in electricity production, generating about 4116 billion kWh in 2021, of which coal accounted for 21.8% of the total. This study applies an integrated approach using both terrestrial and satellite data to specifically examine emissions from coal-fired power plants and its spatial extent. The study also highlights the effectiveness of government policies to reduce emissions. It was found that emission of pollutants from the country's energy sector has been steadily declining, with annual emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) decreasing from the US electric power sector between 1990 and 2020 by 93.4% and 84.8%, respectively, and carbon dioxide (CO2) by 37% between 2007 and 2020. Although overall emissions from coal-fired power plants are declining, some individual plants have yet to install environmental equipment to control emissions. According to US government data, major emitters of SO2, NOx, and CO2 in the US are the Martin Lake power plant in East Texas, the Labadie power plant near St. Louis, Missouri, and the James H Miller Jr plant near Birmingham, Alabama. This study also integrates TROPOMI satellite data to detect point emissions from individual power plants. While the highest levels of measured pollutants were over the country's major cities and areas of fossil fuel extraction, TROPOMI could clearly distinguish the pollution caused by power plants in more rural areas. Although the US has made great strides in reducing emissions from coal-fired power plants, these plants still represent a major source of pollution and remain a major concern. Totally eliminating coal as a power source will be difficult with the higher power demands resulting from the transition to electric automobiles.  相似文献   

5.
To stabilize the atmospheric concentration of greenhouse gases (GHG), a huge reduction of carbon dioxide (CO2) emissions is required. Although some people believe that this necessitates a considerable reduction in the use of fossil fuels or fuel switching, other options are available that allow the use of fossil fuels and reduce atmospheric emissions of CO2. Sequestration of CO2 from fossil fuel combustion in the subsurface could prevent the CO2 from reaching the surface for millions of years. Geological sequestration of CO2 in deep aquifers or in depleted oil and gas reservoirs is a mature technology. Despite the huge quantities of CO2 that can be sequestered in this way, this approach does not provide any economic benefit. This paper discusses a third option, which consists of injecting CO2 in deep coal seams to sequester the carbon and enhance the recovery of coalbed methane (CBM). Waste CO2 from CBM-fueled power plants could be injected into CBM reservoirs to produce more methane (CH4) for the power plant. The 2:1 coal-sorption selectivity for CO2 over CH4 supports the feasibility of operating fossil-fueled power plants without atmospheric CO2 emissions. Other CO2 sequestration technologies, such as ocean disposal and biofixation, are briefly discussed and the suitability of these approaches is evaluated for use in Alberta, Canada.  相似文献   

6.
The cylindrical coal samples were subjected to three successive cycles of sorption–desorption processes of a single gas (CO2, CH4). Acoustic emission (AE) and strains were simultaneously recorded during the sorption and desorption processes.Tests were conducted on medium-rank coal from the Upper Silesia Basin, Poland. Follow-up tests for gas sorption–desorption consistently showed significant changes of AE characteristics for re-runs on the same sample. The AE level decreased in each successive test. The most spectacular differences were observed between AE generated during the first cycle of gas sorption and the subsequent cycle. This phenomenon could be due to structural changes in the coal taking place substantially on its first exposure to the sorbate. The AE results indicate, that each cycle of gas sorption–desorption was run on the same coal though with a somewhat different structure.In those tests, the swelling of coal by CO2 or/and CH4 was anisotropic (greater in the direction perpendicular to the bedding plane than parallel) in each cycle of the gas sorption–desorption process.  相似文献   

7.
This study investigates the occurrence of greenhouse gases (GHGs) and the role of groundwater as an indirect pathway of GHG emissions into surface waters in a gaining stretch of the Triffoy River agricultural catchment (Belgium). To this end, nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations, the stable isotopes of nitrate, and major ions were monitored in river and groundwater over 8 months. Results indicated that groundwater was strongly oversaturated in N2O and CO2 with respect to atmospheric equilibrium (50.1 vs. 0.55 μg L?1 for N2O and 14,569 vs. 400 ppm for CO2), but only marginally for CH4 (0.45 vs. 0.056 μg L?1), suggesting that groundwater can be a source of these GHGs to the atmosphere. Nitrification seemed to be the main process for the accumulation of N2O in groundwater. Oxic conditions prevailing in the aquifer were not prone for the accumulation of CH4. In fact, the emissions of CH4 from the river were one to two orders of magnitude higher than the inputs from groundwater, meaning that CH4 emissions from the river were due to CH4 in-situ production in riverbed or riparian zone sediments. For CO2 and N2O, average emissions from groundwater were 1.5?×?105 kg CO2 ha?1 year?1 and 207 kg N2O ha?1 year?1, respectively. Groundwater is probably an important source of N2O and CO2 in gaining streams but when the measures are scaled at catchment scale, these fluxes are probably relatively modest. Nevertheless, their quantification would better constrain nitrogen and carbon budgets in natural systems.  相似文献   

8.
This paper studied the CO2-EGR in Altmark natural gas field with numerical simulations. The hydro-mechanical coupled simulations were run using a linked simulator TOUGH2MP-FLAC3D. In order to consider the gas mixing process, EOS7C was implemented in TOUGH2MP. A multi-layered 3D model (4.4 km × 2 km × 1 km) which consists of the whole reservoir, caprock and base rock was generated based on a history-matched PETREL model, originally built by GDF SUEZ E&P Deutschland GmbH for Altmark natural gas field. The model is heterogeneous and discretized into 26,015 grid blocks. In the simulation, 100,000 t CO2 was injected in the reservoir through well S13 within 2 years, while gas was produced from the well S14. Some sensitivity analyses were also carried out. Simulation results show that CO2 tends to migrate toward the production well S14 along a NW–SE fault. It reached the observation wells S1 and S16 after 2 years, but no breakthrough occurred in the production well. After 2 years of CO2 injection, the reservoir pressure increased by 2.5 bar, which is beneficial for gas recovery. The largest uplift (1 mm) occurred at the bottom of the caprock. The deformation was small (elastic) and caprock integrity was not affected. With the injection rate doubled the average pressure increased by 5.3 bar. Even then the CO2 did not reach the production well S14 after 2 years of injection. It could be concluded that the previous flow field was established during the primary gas production history. This former flow field, including CO2 injection/CH4 production rate during CO2-EGR and fault directions and intensity are the most important factors affecting the CO2 transport.  相似文献   

9.
Summary Continuous gas monitoring has been performed in three development panels at No. 2 Mine, Collinsville, Queensland, Australia to assess seam gassiness at the mining face as an indication of outburst-proneness. The first panel monitored encountered two outbursts during mining of virgin conditions, and a third outburst occurred on the fringe of a gas-drained block, adjacent to a thrust fault. The second panel successfully mined through the thrust fault without outbursting and finally halted due to high gas emissions. The third panel mined through a gas-drained block of coal, where an overall substantial reduction in gas emission was observed.The results from all three panels have been analysed and compared to establish parameters for outburst-proneness assessment, based on a face cut-out cycle (FCC) CO2 emission. For FCC CO2 emissions less than 2.6 m3 t–1, no outbursting occurs, and normal mining proceeds. Up to 3.8 m3 t–1, low-medium outburst-prone conditions exist and mining takes place under controlled procedures. When values exceed 3.8 m3 t–1, high outburst-prone conditions exist and mining is halted.  相似文献   

10.
Siyue Li  X. X. Lu 《Natural Hazards》2012,62(3):1343-1345
Anthropogenic greenhouse gas (GHG) emissions have substantially contributed to intensification of heavy precipitation and thus the risk of flood occurrence, and this anthropogenic climate change is now likely to continue for many centuries. Thus, precise quantification of human-induced GHG emissions is urgently required for modeling future global warming and precipitation changes, which is strongly linked to flood disasters. Recently, GHG evasion from hydroelectric reservoirs was estimated to be 48 Tg C as CO2 and 3 Tg C as CH4 annually, lower than earlier estimate (published in Nature Geoscience; 2011). Here, we analyzed the uncertainties of GHG emissions from hydroelectric reservoirs, that is, reservoir surface area, data paucity and carbon emission relating to ecological zone, and argued that GHG evasion from global hydroelectric reservoirs has been largely under-estimated. Our study hopes to improve the quantification for future researches.  相似文献   

11.
The storage of CO2 in unused coal mines is a viable option for reducing emissions of CO2, whose accumulation in the atmosphere is one of the main contributors to global warming. Understanding CO2 behaviour and storage capacity of the coal is an important first step before injecting the CO2. We used experimental equipment to extract coal from a mine and to obtain a representative sample of both its internal structure (in terms of cleats, macropores, mesopores and micropores) and occluded gases. Storage capacity was studied in terms of variations in gas pressure. The adsorption isotherm was experimentally obtained applying a procedure specifically designed to avoid altering the coal. An unused coal bed was selected to determine how much CO2 it could adsorb and to study the feasibility of storing power plant CO2 in this kind of mine.  相似文献   

12.
Presently many research projects focus on the reduction of anthropogenic CO2 emissions. It is intended to apply underground storage techniques such as flue gas injection in unminable coal seams. In this context, an experimental study has been performed on the adsorption of pure CO2 and preferential sorption behavior of flue gas. A coal sample from the Silesian Basin in Poland (0.68% V Rr), measured in the dry and wet state at 353 K has been chosen for this approach. The flue gas used was a custom class industrial flue gas with 10.9% of CO2, 0.01% of CO, 9% of H2, 3.01% of CH4, 3.0% of O2, 0.106% of SO2 and nitrogen as balance.Adsorption isotherms of CO2 and flue gas were measured upto a maximum of 11 MPa using a volumetric method. Total excess sorption capacities for CO2 on dry and wet Silesia coal ranged between 1.9 and 1.3 mmol/g, respectively. Flue gas sorption capacities on dry and wet Silesia coal were much lower and ranged between 0.45 and 0.2 mmol/g, respectively, at pressures of 8 MPa. The low sorption capacity of wet coal has resulted from water occupying some of the more active adsorption sites and hence reducing the heterogeneity of adsorption sites relative to that of dry coal. Desorption tests with flue gas were conducted to study the degree of preferential sorption of the individual components. These experiments indicate that CO2 is by far the prefered sorbing component under both wet and dry conditions. This is followed by CH4. N2 adsorbs very little on the coal in the presence of CO2 and CH4. It is also observed that the adsorption of CO2 onto coal is not significantly hindered by the addition of other gases, other than dilution effect of the pressure.In addition to the sorption experiments, the density of the flue gas mixture has been determined up to 18 MPa at 318 K. A very good precision of these measurements were documented by volumetric methods.  相似文献   

13.
We estimated CO2 and CH4 emissions from mangrove-associated waters of the Andaman Islands by sampling hourly over 24 h in two tidal mangrove creeks (Wright Myo; Kalighat) and during transects in contiguous shallow inshore waters, immediately following the northeast monsoons (dry season) and during the peak of the southwest monsoons (wet season) of 2005 and 2006. Tidal height correlated positively with dissolved O2 and negatively with pCO2, CH4, total alkalinity (TAlk) and dissolved inorganic carbon (DIC), and pCO2 and CH4 were always highly supersaturated (330–1,627 % CO2; 339–26,930 % CH4). These data are consistent with a tidal pumping response to hydrostatic pressure change. There were no seasonal trends in dissolved CH4 but pCO2 was around twice as high during the 2005 wet season than at other times, in both the tidal surveys and the inshore transects. Fourfold higher turbidity during the wet season is consistent with elevated net benthic and/or water column heterotrophy via enhanced organic matter inputs from adjacent mangrove forest and/or the flushing of CO2-enriched soil waters, which may explain these CO2 data. TAlk/DIC relationships in the tidally pumped waters were most consistent with a diagenetic origin of CO2 primarily via sulphate reduction, with additional inputs via aerobic respiration. A decrease with salinity for pCO2, CH4, TAlk and DIC during the inshore transects reflected offshore transport of tidally pumped waters. Estimated mean tidal creek emissions were ～23–173 mmol m?2 day?1 CO2 and ～0.11–0.47 mmol m?2 day?1 CH4. The CO2 emissions are typical of mangrove-associated waters globally, while the CH4 emissions fall at the low end of the published range. Scaling to the creek open water area (2,700 km2) gave total annual creek water emissions ～3.6–9.2?×?1010 mol CO2 and 3.7–34?×?107 mol CH4. We estimated emissions from contiguous inshore waters at ～1.5?×?1011 mol CO2?year?1 and 2.6?×?108 mol CH4?year?1, giving total emissions of ～1.9?×?1011 mol CO2?year?1 and ～3.0?×?108 mol CH4?year?1 from a total area of mangrove-influenced water of ～3?×?104 km2. Evaluating such emissions in a range of mangrove environments is important to resolving the greenhouse gas balance of mangrove ecosystems globally. Future such studies should be integral to wider quantitative process studies of the mangrove carbon balance.  相似文献   

14.
Facilitated by fuel economy, climate legislation and government policy, sales of light-duty plug-in hybrid and battery electric vehicles are rapidly increasing during the last decade. But their energy and emissions impact have not been fully investigated, particularly accounting for energy and emissions during electricity generation. In this study, we conducted in-use energy consumption and emissions measurements of a plug-in and a battery electric vehicle under real-world city and highway driving conditions. We further compare them with energy consumption and emissions from counterpart conventional vehicles under the same driving conditions, to exclude benefits due to different vehicle specifications. Our results show that both the plug-in hybrid and battery electric vehicles can achieve about 50% energy benefits compared with their counterpart conventional vehicles, mainly through capturing regenerative energy. But when vehicles are tested in high-speed or high-acceleration driving conditions, the distance-normalized life-cycle CO2 emissions of plug-in hybrid and battery electric vehicles are higher to their counterpart gasoline powered vehicles. The CO2 emissions comparison results can vary based on the location and time of electricity generation. Therefore, our results confirm that benefits of promoting electric vehicles should consider temporal and spatial aspects of electricity generation.  相似文献   

15.
While the Intergovernmental Panel on Climate Change classifies coal as anthracite, bituminous coal, and sub-bituminous coal, Korea only distinguishes coal as anthracite and bituminous coal while sub-bituminous coal is considered bituminous coal. As a result, Korea conducted research in the CO2 emission factors of anthracite and bituminous coal, but largely ignored sub-bituminous coal. Therefore, the purpose of this research is to develop the CO2 emission factor of sub-bituminous coal by classifying sub-bituminous coal from resources of bituminous coal activities collected in Korea between 2007 and 2011. The 2007–2011 average carbon content of sub-bituminous coal was analyzed to be 69.63 ± 3.11 %, the average hydrogen content 4.97 ± 0.37 %, the inherent moisture 12.60 ± 4.33 %, the total moisture 21.91 ± 5.45 %, and the dry-based gross calorific value was analyzed to be 5,914 ± 391 kcal/kg; using these analyzed values, the as-received net calorific value was found to be 20.75 ± 7.59 TJ/Gg and the CO2 emission factor was found to be 96,241 ± 4,064 kg/TJ. In addition, the 62.7 million ton amount for the 2009 greenhouse gas emission from sub-bituminous coal as estimated with the analyzed value of this study is an amount that is equivalent to 11.1 % of the 2009 total greenhouse gas emission amount of 564.7 million tons, and this amount is larger than the 9.3 % for the industrial processes sector, 3.3 % for the agricultural sector and 2.5 % for the waste sector. Therefore, it is important to reflect the realities of Korea when estimating the greenhouse gas emission from such sub-bituminous coals.  相似文献   

16.
The devastating effects of fossil fuels on the environment, limited natural sources and increasing demand for energy across the world make renewable energy sources more important than in the past. The 2015 United Nations Climate Change Conference resulted in a global agreement on net zero CO2 emissions shortly after the middle of the twenty-first century, which will lead to a collapse of fossil fuel demand. The focus of the study is to define a cost optimal 100% renewable energy system in Iran by 2030 using an hourly resolution model. The optimal sets of renewable energy technologies, least-cost energy supply, mix of capacities and operation modes were calculated and the role of storage technologies was examined. Two scenarios have been evaluated in this study: a country-wide scenario and an integrated scenario. In the country-wide scenario, renewable energy generation and energy storage technologies cover the country’s power sector electricity demand. In the integrated scenario, the renewable energy generated was able to fulfil both the electricity demand of the power sector and the substantial electricity demand for water desalination and synthesis of industrial gas. By adding sector integration, the total levelized cost of electricity decreased from 45.3 to 40.3 €/MWh. The levelized cost of electricity of 40.3 €/MWh in the integrated scenario is quite cost-effective and beneficial in comparison with other low-carbon but high-cost alternatives such as carbon capture and storage and nuclear energy. A 100% renewable energy system for Iran is found to be a real policy option.  相似文献   

17.
The history of life on Earth is critically dependent on the carbon, sulfur and oxygen cycles of the lithosphere – hydrosphere – atmosphere – biosphere system. An Archean oxygen-poor greenhouse atmosphere developed through: (i) accumulation of CO2 and CH4 from episodic injections of CO2 from volcanic activity, volatilised crust impacted by asteroids and comets, metamorphic devolatilisation processes and release of methane from sediments; and (ii) little CO2 weathering-capture due to both high temperatures of the hydrosphere (low CO2 solubility) and a low ratio of exposed continents to oceans. In the wake of the Sturtian glaciation, enrichment in oxygen and appearance of multicellular eukaryotes heralded the onset of the Phanerozoic where greenhouse conditions were interrupted by periods of strong CO2-sequestration through intensified capture of CO2 by marine plants, onset of land plants and burial of carbonaceous shale and coal (Late Ordovician; Carboniferous – Permian; Late Jurassic; Late Tertiary – Quaternary). The progression from Late Mesozoic and Early Tertiary greenhouse conditions to Late Tertiary – Quaternary ice ages was related to the sequestration of CO2 by rapid weathering of the emerging Alpine and Himalayan mountain chains. A number of peak warming and sea-level-rise events include the Late Oligocene, mid-Miocene, mid-Pliocene and Pleistocene glacial terminations. The Late Tertiary – Quaternary ice ages were dominated by cyclic orbital-forcing-triggered terminations which involved CO2-feedback effects from warming seas and the biosphere and albedo flips due to ice-sheet melting. Since ca AD 1750 human emissions were ～305 Gt of carbon, as compared with ～750 Gt C in the atmosphere. The emissions constitute ～12% of the terrestrial biosphere and ～10% of the known global fossil fuel reserve of ～4000 Gt C, whose combustion would compare to the ～ 4600 Gt C released to the atmosphere during the K – T impact event 65 million years ago, with associated ～65% mass extinction of species. The current growth rate of atmospheric greenhouse gases and global mean temperatures exceed those of Pleistocene glacial terminations by one to two orders of magnitude. The relationship between temperatures and sea-levels for the last few million years project future sea-level rises toward time-averaged values of at least 5 m per 1°C. The instability of ice sheets suggested by the Dansgaard – Oeschinger glacial cycles during 50 – 20 ka, observed ice melt lag effects of glacial terminations, spring ice collapse dynamics and the doubling per-decade of Greenland and west Antarctic ice melt suggest that the Intergovernmental Panel on Climate Change's projected sea-level rises (<59 cm) for the 21st century may be exceeded. The biological and philosophical rationale underlying climate change and mass extinction perpetrated by an intelligent carbon-emitting mammal species may never be known.  相似文献   

18.
Over the past few decades, substantial progress has been made to overcome the technical difficulties of continuously measuring volcanic SO2 emissions. However, measurements of CO2 emissions still present many difficulties, partly due to the lack of instruments that can directly measure CO2 emissions and partly due to its strong atmospheric background. In order to overcome these difficulties, a commonly taken approach is to combine differential optical absorption spectroscopy (DOAS) by using NOVAC scan-DOAS instruments for continuous measurements of crateric SO2 emissions, and electrochemical/NDIR multi-component gas analyser system (multi-GAS) instruments for measuring CO2/SO2 ratios of excerpts of the volcanic plume. This study aims to quantify the representativeness of excerpts of CO2/SO2 ratios measured by Multi-GAS as a fraction of the whole plume composition, by comparison with simultaneously measured CO2/SO2 ratios using cross-crater Fourier transform infrared spectroscopy (FTIR). Two study cases are presented: Telica volcano (Nicaragua), with a homogenous plume, quiescent degassing from a deep source and ambient temperature, and Turrialba volcano (Costa Rica), which has a non-homogeneous plume from three main sources with different compositions and temperatures. Our comparison shows that in our “easier case” (Telica), FTIR and Multi-GAS CO2/SO2 ratios agree within a factor about 3 %. In our “complicated case” (Turrialba), Multi-GAS and FTIR yield CO2/SO2 ratios differing by approximately 13–25 % at most. These results suggest that a fair estimation of volcanic CO2 emissions can be provided by the combination of DOAS and Multi-GAS instruments for volcanoes with similar degassing conditions as Telica or Turrialba. Based on the results of this comparison, we report that by the time our measurements were made, Telica and Turrialba were emitting approximately 100 and 1,000 t day?1 of CO2, respectively.  相似文献   

19.
Interpretation of carbon dioxide diffusion behavior in coals   总被引：3，自引：1，他引：3  
Storage of carbon dioxide in geological formations is for many countries one of the options to reduce greenhouse gas emissions and thus to satisfy the Kyoto agreements. The CO2 storage in unminable coal seams has the advantage that it stores CO2 emissions from industrial processes and can be used to enhance coalbed methane recovery (CO2-ECBM). For this purpose, the storage capacity of coal is an important reservoir parameter. While the amount of CO2 sorption data on various natural coals has increased in recent years, only few measurements have been performed to estimate the rate of CO2 sorption under reservoir conditions. An understanding of gas transport is crucial for processes associated with CO2 injection, storage and enhanced coalbed methane (ECBM) production.A volumetric experimental set-up has been used to determine the rate of sorption of carbon dioxide in coal particles at various pressures and various grain size fractions. The pressure history during each pressure step was measured. The measurements are interpreted in terms of temperature relaxation and transport/sorption processes within the coal particles. The characteristic times of sorption increase with increasing pressure. No clear dependence of the characteristic time with respect to the particle size was found. At low pressures (below 1 MPa) fast gas diffusion is the prevailing mechanism for sorption, whereas at higher pressures, the slow diffusion process controls the gas uptake by the coal.  相似文献   

20.
Carbon monoxide (CO) and carbon dioxide (CO2) emissions during a spontaneous heating event in a coal mine are important gases to monitor for detecting the spontaneous heating at an early stage. However, in underground coal mines, the CO and CO2 concentrations and their related fire ratios may be affected by mine ventilation. In this study, CO and CO2 emissions from spontaneous heating of a U.S. coal sample were evaluated in an isothermal oven under different airflow ventilation rates ranging from 100 to 500 cm3/min. Laboratory experiments were conducted at oven temperatures of 70, 90, and 100 °C. The temperature at the center of the coal sample was continually monitored, while the CO, CO2, and oxygen (O2) concentrations of the exit gas were continually measured. The results indicate that CO was generated immediately after the airflow passed through the coal, while CO2 was generated in a late phase. The amounts of CO generated under different airflow rates were approximately the same at the initial temperature of 70 °C, while the amounts of CO generated increased significantly as the airflow rates and initial temperatures increased. The ratio of CO/CO2 was found to be independent of airflow rate and initial temperature, approaching a constant value of 0.2 quickly if there was no thermal runaway. The value tended to decrease when a thermal runaway took place. The CO/O2 deficiency ratio was dependent on both airflow rates and the initial temperature. The experimental results are in qualitative agreement with some large-scale test and field monitoring results.  相似文献   

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