Displacement behavior of CH4 adsorbed on coals by injecting pure CO2, N2, and CO2–N2 mixture

Gas adsorption isotherms of Akabira coals were established for pure carbon dioxide (CO₂), methane (CH₄), and nitrogen (N₂). Experimental data fit well into the Langmuir model. The ratio of sorption capacity of CO₂, CH₄, and N₂ is 8.5:3.5:1 at a lower pressure (1.2 MPa) regime and becomes 5.5:2:1 when gas pressure increases to 6.0 MPa. The difference in sorption capacity of these three gases is explained by differences in the density of the three gases with increasing pressure. A coal–methane system partially saturated with CH₄ at 2.4 MPa adsorption pressure was experimentally studied. Desorption behavior of CH₄ by injecting pure CO₂ (at 3.0, 4.0, 5.0, and 6.0 MPa), and by injecting the CO₂–N₂ mixture and pure N₂ (at 3.0 and 6.0 MPa) were evaluated. Results indicate that the preferential sorption property of coal for CO₂ is significantly higher than that for CH₄ or N₂. CO₂ injection can displace almost all of the CH₄ adsorbed on coal. When modeling the CH₄–CO₂ binary and CH₂–CO₂–N₂ ternary adsorption system by using the extended Langmuir (EL) equation, the EL model always over-predicted the sorbed CO₂ value with a lower error, while under-predicting the sorbed CH₄ with a higher error. A part of CO₂ may dissolve into the solid organic structure of coal, besides its competitive adsorption with other gases. According to this explanation, the EL coefficients of CO₂ in EL equation were revised. The revised EL model proved to be very accurate in predicting sorbed ratio of multi-component gases on coals.     

夏季长江口潮间带CH4、CO2和N2O通量特征

使用原位静态箱现场采样,对夏季(7月和8月)长江口崇明东滩湿地3种主要温室气体CO2、CH4和N2O的界面通量进行了同步观测.结果表明,夏季低潮滩是大气CH4的排放源(40.2 μg/(m2·h)),CO2和N2O的吸收汇(通量值分别为-86.3 mg/(m2·h),-27.6 μg/(m2·h)).7月和8月中潮滩是3种温室气体的排放源,CH4日平均排放速率达到6.56 mg/(m2·h),CO2为301 mg/(m2·h),N2O为69.9 μg/(m2·h).温度(气温和不同深度地温)、沉积物有机碳含量以及潮滩植被海三棱藨草和沉积物表层藻类的光合和呼吸是决定CH4、CO2、N2O产生、排放和吸收的主要因素.相关分析表明中潮滩气体排放通量与温度(气温和不同深度地温)呈显著正相关关系,但在低潮滩气体通量与温度的相关关系不明显.     

Adsorption kinetics of CO2, CH4, and their equimolar mixture on coal from the Black Warrior Basin,West-Central Alabama

Laboratory experiments were conducted to investigate the adsorption kinetic behavior of pure and mixed gases (CO_2, CH₄, approximately equimolar CO₂ + CH₄ mixtures, and He) on a coal sample obtained from the Black Warrior Basin at the Littleton Mine (Twin Pine Coal Company), Jefferson County, west-central Alabama. The sample was from the Mary Lee coal zone of the Pottsville Formation (Lower Pennsylvanian). Experiments with three size fractions (45–150 µm, 1–2 mm, and 5–10 mm) of crushed coal were performed at 40 °C and 35 °C over a pressure range of 1.4–6.9 MPa to simulate coalbed methane reservoir conditions in the Black Warrior Basin and provide data relevant for enhanced coalbed methane recovery operations. The following key observations were made: (1) CO₂ adsorption on both dry and water-saturated coal is much more rapid than CH₄ adsorption; (2) water saturation decreases the rates of CO₂ and CH₄ adsorption on coal surfaces, but it appears to have minimal effects on the final magnitude of CO₂ or CH₄ adsorption if the coal is not previously exposed to CO₂; (3) retention of adsorbed CO₂ on coal surfaces is significant even with extreme pressure cycling; and (4) adsorption is significantly faster for the 45–150 μm size fraction compared to the two coarser fractions.     

Role of CO2 and CH4 in Hydrothermal Ore-forming System

Please refer to the attachment(s) for more details.     

Strain development in unconfined coals exposed to CO2, CH4 and Ar: Effect of moisture

Field experiments and laboratory studies have shown that swelling of coal takes place upon contact with carbon dioxide at underground pressure and temperature conditions. Understanding this swelling behavior is crucial for predicting the performance of future carbon dioxide sequestration operations in unminable coal seams conducted in association with methane production. Swelling is believed to be related to adsorption on the internal coal surface. Whereas it is well established that moisture influences the sorption capacity of coal, the influence of water on coal swelling is less well-defined. This paper presents the results of laboratory experiments to investigate the effect of moisture on coal swelling in the presence of carbon dioxide, methane and argon. Strain development of an unconfined sample of about 1.0–1.5 mm³ at 40 °C and 8 MPa (and at other pressures) was observed in an optical cell under a microscope as a function of time. Both air dried and moisturized samples were used. Results confirmed different swelling behaviors of coal with different substances: carbon dioxide leads to higher strain than methane, while exposure to argon leads to very little swelling. The experiments on moisturized samples seem to confirm the role of moisture as a competitor to gas molecules for adsorption sites. Adsorption of water could also explain the observed swelling due to water uptake at atmospheric pressure. A re-introduction of carbon dioxide, after intermediate gas release, results in higher strains which indicate a drying effect of the carbon dioxide on the coal. The results of this study show that the role of water cannot be ignored if one wants to understand the fundamental processes that are taking place in enhanced coalbed methane operations.     

Dike intrusions into bituminous coal, Illinois Basin: H, C, N, O isotopic responses to rapid and brief heating

Unlike long-term heating in subsiding sedimentary basins, the near-instantaneous thermal maturation of sedimentary organic matter near magmatic intrusions is comparable to artificial thermal maturation in the laboratory in terms of short duration and limited extent. This study investigates chemical and H, C, N, O isotopic changes in high volatile bituminous coal near two Illinois dike contacts and compares observed patterns and trends with data from other published studies and from artificial maturation experiments. Our study pioneers in quantifying isotopically exchangeable hydrogen and measuring the D/H (i.e., ²H/¹H) ratio of isotopically non-exchangeable organic hydrogen in kerogen near magmatic contacts. Thermal stress in coal caused a reduction of isotopically exchangeable hydrogen in kerogen from 5% to 6% in unaltered coal to 2-3% at contacts, mostly due to elimination of functional groups (e.g., OH, COOH, NH₂). In contrast to all previously published data on D/H in thermally matured organic matter, the more mature kerogen near the two dike contacts is D-depleted, which is attributed to (i) thermal elimination of D-enriched functional groups, and (ii) thermal drying of hydrologically isolated coal prior to the onset of cracking reactions, thereby precluding D-transfer from relatively D-enriched water into kerogen. Maxima in organic nitrogen concentration and in the atomic N/C ratio of kerogen at a distance of ∼2.5 to ∼3.5 m from the thicker dike indicate that reactive N-compounds had been pyrolytically liberated at high temperature closer to the contact, migrated through the coal seam, and recombined with coal kerogen in a zone of lower temperature. The same principle extends to organic carbon, because a strong δ¹³C_kerogen vs. δ¹⁵N_kerogen correlation across 5.5 m of coal adjacent to the thicker dike indicates that coal was functioning as a flow-through reactor along a dynamic thermal gradient facilitating back-reactions between mobile pyrolysis products from the hot zone as they encounter less hot kerogen. Vein and cell filling carbonate is most abundant in highest rank coals where carbonate δ¹³C_VPDB and δ¹⁸O_VSMOW values are consistent with thermal generation of ¹³C-depleted and ¹⁸O-enriched CO₂ from decarboxylation and pyrolysis of organic matter. Lower background concentrations of ¹³C-enriched carbonate in thermally unaffected coal may be linked to ¹³C-enrichment in residual CO₂ in the process of CO₂ reduction via microbial methanogenesis.Our compilation and comparison of available organic H, C, N isotopic findings on magmatic intrusions result in re-assessments of majors factors influencing isotopic shifts in kerogen during magmatic heating. (i) Thermally induced shifts in organic δD values of kerogen are primarily driven by the availability of water or steam. Hydrologic isolation (e.g., near Illinois dikes) results in organic D-depletion in kerogen, whereas more common hydrologic connectivity results in organic D-enrichment. (ii) Shifts in kerogen (or coal) δ¹³C and δ¹⁵N values are typically small and may follow sinusoidal patterns over short distances from magmatic contacts. Laterally limited sampling strategies may thus result in misleading and non-representative data. (iii) Fluid transport of chemically active, mobile carbon and nitrogen species and recombination reactions with kerogen result in isotopic changes in kerogen that are unrelated to the original, autochthonous part of kerogen.     

Effects of water table changes on soil CO2, CH4 and N2O fluxes during the growing season in freshwater marsh of Northeast China

A field control experiment was carried out to determine the influence of water table changes on soil CO₂, CH₄, and N₂O emissions in Calamagrostis angustifolia freshwater marsh in Northeast of China. The results showed that the water depth of 5 cm below the ground surface increased soil CO₂ emission, but there was no significant influence of deeper water table on gas emission. CH₄ emission was accelerated by deep standing water and approached the peak in the plant booming time. This suggests that root activity has influence on CH₄ production. The result also demonstrated that both low water table level and inundated environment would inhibit N₂O emission. Comparing the total global warming potential of three gases under different conditions, it can be concluded that maintaining a comparatively steady water table near the soil surface can benefit soil carbon sequestration in the C. angustifolia marsh, and decrease of the greenhouse gases emissions to the atmosphere.     

开滦矿区低级烟煤大分子结构演化特征及CO成因

针对开滦矿区CO超标现象,进行了煤分子结构演化特征及CO成因研究。通过对22个煤样的工业指标、元素组成、镜质组最大反射率(R_max)、红外光谱和扫描电镜分析,结果发现:煤样的H/C先随R_max增加,在R_max达到0.8%后又迅速减少;煤样中富含C=O、C-O、-O-等含氧基团,通过对芳碳率(f_a)、环缩合度指数(2(R-1)/C)与R_max的关联,发现随着R_max的增加,f_a先增加后减少,2(R-1)/C先减少后增加,拐点均在R_max为0.8%处;煤样孔隙结构为粒间孔。研究认为,开滦矿区煤层赋存CO的成因是,变质作用过程中(R_max为0.8%时),煤分子侧链因构造应力作用断裂、脱落产生大量自由基,进而结合生成CO,并赋存在煤层中保留下来。     

A multi-methodological approach to determine CO2 and CH4 fluxes and concentrations in solid waste disposal

The municipal solid waste （MSW） landfills are the significant sources of atmospheric contamination, due to biogas production by anaerobic decomposition of organic matter via bacterial activity. Biogas released from landfills is commonly composed of a mixture of methane （55%-60%） and carbon dioxide （40%-45%）, with minor contents of N2, H2, CO and traces of toxic and bad smelling inorganic and organic compounds. Particular attention has to be paid to CH4 and CO2 because of their liability for the greenhouse effect. Presently, the U.S. methane emission from landfills is considered to be about 25% of the total methane released to the atmosphere. Accordingly, field measurements should be planned in order to verify and, eventually, optimize the amount of gases released from waste disposals to the atmosphere. Simultaneous measurements of methane and carbon dioxide fluxes are an effective tool to better evaluate： （1） the amount of biogas released, （2） the real efficiency of the impervious cover, and （3） the presence of anomalous degassing zones or of newly formed fractures. Static closed-chamber methods for CH4 and CO2 flux measurements have been developed and used in both natural and artificial systems. Furthermore, portable gas-chromatographers equipped with flame ionization detector （FID） and accumulation chamber connected to infrared detectors （IR） .have been utilized for measuring CH4 and CO2 fluxes, respectively. This paper deals with a detailed investigation that combines （1） CH4 and CO2 flux measurements from solid waste disposal and surrounding areas （determined by an accumulation chamber equipped with two IR detectors, respectively）, （2） chemical composition of soil and piezometer gases （collected in pre-evacuated glass tubes and analyzed by gas-chromatography）, and （3） CO2 linear concentration measurements on optical air paths with IR laser devices. This multi-methodological approach was successfully applied to an active MSW in Tuscany （Central Italy）. The analytical results have shown that the CO2/CH4 ratios of the piezometer gases have large variations, likely related to the different stage of decomposition processes affecting the heterogeneous solid material of the waste landfill. Significant contents of light hydrocarbons and BTX were also detected.     

生物气CO2还原途径中碳同位素分馏作用研究及应用

地质历史中,CO2/H2还原产甲烷作用对生物气的形成具有十分重要的意义。中国柴达木盆地第四系生物气主要为CO2/H2还原型生物气。笔者以CO2/H2还原生气理论为指导,进行不同初始碳同位素值和不同赋存状态碳源的生物模拟实验,研究CO2/H2还原产气过程中发生的碳同位素分馏作用。实验结果表明,产物中δ13CH4值与底物的δ13C值呈很好的正相关关系;在反应母质过量的情况下,碳源的赋存状态可以影响产物甲烷的碳同位素组成。以游离形式CO2还原产生的甲烷δ13C值,相对于以HCO3-、CO23-离子形式产生的甲烷δ13C值轻。通过柴达木盆地东部第四系生物气田实例分析,探讨了该区生物气的主要底物CO2的来源及赋存状态,对评价盆地生物气资源和有利勘探区预测有重要的参考价值。     

CBM and CO2-ECBM related sorption processes in coal: A review

This article reviews the state of research on sorption of gases (CO₂, CH₄) and water on coal for primary recovery of coalbed methane (CBM), secondary recovery by an enhancement with carbon dioxide injection (CO₂-ECBM), and for permanent storage of CO₂ in coal seams.Especially in the last decade a large amount of data has been published characterizing coals from various coal basins world-wide for their gas sorption capacity. This research was either related to commercial CBM production or to the usage of coal seams as a permanent sink for anthropogenic CO₂ emissions. Presently, producing methane from coal beds is an attractive option and operations are under way or planned in many coal basins around the globe. Gas-in-place determinations using canister desorption tests and CH₄ isotherms are performed routinely and have provided large datasets for correlating gas transport and sorption properties with coal characteristic parameters.Publicly funded research projects have produced large datasets on the interaction of CO₂ with coals. The determination of sorption isotherms, sorption capacities and rates has meanwhile become a standard approach.In this study we discuss and compare the manometric, volumetric and gravimetric methods for recording sorption isotherms and provide an uncertainty analysis. Using published datasets and theoretical considerations, water sorption is discussed in detail as an important mechanisms controlling gas sorption on coal. Most sorption isotherms are still recorded for dry coals, which usually do not represent in-seam conditions, and water present in the coal has a significant control on CBM gas contents and CO₂ storage potential. This section is followed by considerations of the interdependence of sorption capacity and coal properties like coal rank, maceral composition or ash content. For assessment of the most suitable coal rank for CO₂ storage data on the CO₂/CH₄ sorption ratio data have been collected and compared with coal rank.Finally, we discuss sorption rates and gas diffusion in the coal matrix as well as the different unipore or bidisperse models used for describing these processes.This review does not include information on low-pressure sorption measurements (BET approach) to characterize pore sizes or pore volume since this would be a review of its own. We also do not consider sorption of gas mixtures since the data base is still limited and measurement techniques are associated with large uncertainties.     

Striated conical structures and related fractures in bituminous coal of the southern Canadian Rocky Mountains

Striated structures, many of which are conical in form, are common mesoscopic features in bituminous and semi-anthracite coals of the southern Canadian Rocky Mountains. The structures are planar, conical to pyramidal in outline and are characterized by striae which radiate from a common apex and bifurcate or “horsetail” to form secondary structures on the master surface. They are up to 20 cm in length, 4 cm in width and have apical angles varying from 10° to 50°. The striated structures occur at numerous localities in both highly sheared and relatively unsheared coal seams.The conical striated structures closely resemble some shatter cones developed in fine-grained rocks, whereas the planar striated structures are somewhat similar to chevron-structured, hackle-marked joints. The pyramidal structures are apparently unique to coal. All three types of structures are considered to be the result of brittle shear fracture based on their occurrence, orientation, and morphology. The apparently restricted occurrence of the structures to coal is likely a function of the homogeneity, and low tensile and compressive strength of bituminous and semi-anthracite coals, possibly augmented by high inter- and/or intra-particle gas pressure resulting from devolatization of the coal during progressive coalification.     

气体(CH4、H2S、CO2等)在水溶液中的溶解度模型

本文介绍一个通过状态方程和特定粒子相互作用理论建立起来的气体在水溶液中的溶解度模型,用以计算气体(CH4、H2S、CO2)在纯水和含盐水溶液中的溶解度、流体包裹体的均一条件、成矿热液沸腾、流体不混溶性、水合物形成条件、CO2地质储藏量等.该模型不仅重现了上百套实验数据(约8000多个数据点),而且具有很强的外延能力.因此适用宽广的温度、压力和盐度范围(CH4:273～523K,1～2000bar,0～6m;H2S:273～500K,0～200bar,O～6m;CO2:273～533K,0～2000bar,0～4.5m),而且精度高、形式简洁.由于使用状态方程和特定粒子相互作用理论相结合的方法,这一模型在无需实验数据的情况下能够拓展到诸如海水和地下热卤水等更为复杂的体系.该模型在国际上得到日益广泛的应用,已被许多国家的同行用以多方面的研究工作,如计算CH4、H2S和CO2气体在水、卤水和海水等天然水溶液不同温度、压力和盐度条件下的溶解度(即水溶液中最大允许的气体含量),分析矿物流体包裹体的PVTX条件(根据包裹体中气体的总含量和均一温度,用该模型就会很方便得到均一化压力,在此基础上还可以迸一步通过状态方程得到密度和等容线)、计算成矿流体的不混溶性或沸腾点、计算CO2地质储藏量、实验校正等方面.相关研究可进行在线计算:www.geochem-model.     

三峡澎溪河水域CO2与CH4年总通量估算

以2010年6月~2011年5月三峡澎溪河回水区CO₂与CH₄通量监测数据为基础,参考澎溪河高阳平湖水域全年4次的24 h昼夜连续跟踪观测结果,对每月各采样点的日通量值进行估算。提出了水下地形划分法和环境因素控制法,将各采样点日通量数据外延至整个回水区水域,并估算了澎溪河回水区水域CO₂与CH₄年总通量值。研究期间,澎溪河回水区全年各采样点CO₂通量均值为(3.05±0.46)mmol/(m2·h);CH₄为(0.050 1±0.009 6)mmol/(m2·h)。以水下地形法为基础,该水域全年CO₂和CH₄总通量分别为40 060.5 t和540.9 t;以环境因素控制法为基础,全年CO₂与CH₄总通量分别为39 073.0 t和467.2 t。以环境要素控制法为参考,该水域CO₂全年平均释放强度为43.26 mmol/(m2·d),在全球水库数据序列中处于中等略偏高水平,CH₄全年平均释放强度为1.42 mmol/(m2·d),在全球水库序列中处于中等水平。     

太湖梅梁湾温室气体(CO2,CH4和N2O)浓度的昼夜变化及其控制因素

营养盐载荷增加、富营养化以及全球增温等对湖泊温室气体的影响目前认识还很有限,原因之一在于对湖泊温室气体产生的动力过程了解不够深入,缺少高时间分辨率的现场观测数据。为了解决这一问题,在富营养的太湖梅梁湾水体,每一小时收集一个样品,直接分析N2 O和CH4饱和度、CO2分压(pCO2)以及其他地球化学参数。在7月份的观测中,N2 O和CH4显示出显著的昼夜变化规律。相关性分析表明,有机质降解是调节湖泊N2 O和CH4变化的重要因素之一。虽然人为活动是控制湖泊温室气体大规模变化的主要因素,但沉积物-水界面的生物地球化学过程对温室气体浓度在短时间尺度上的变化有着重要的影响。研究结果揭示了湖泊温室气体除了受人为活动影响外,湖泊自身的生物地球化学过程也是重要的调控因素之一。     

Carbon-Isotope Characteristics of CO2 and CH4 in Geothermal Springs from the Central Andes

Carbon stable-isotope compositions of coexisting carbon dioxide and methane from geothermal springs across the Central Andes of northern Chile and Bolivia are reported. A total of 60 samples were analyzed for δ¹³C_CO2 and, of these, 10 were selected for δ¹³C_CH4 analyses. The Central Andes are characterized by an active volcanic arc and an unusually thick (up to 75 km) continental crust behind the arc, beneath the high plateau region of the Altiplano. Furthermore, helium-isotope evidence suggests active mantle degassing in a 350-km-wide zone beneath the thick continental crust in the Central Andes (Hoke et al., 1994).

The present results show a wide range of δ¹³C_CO2 (-14.9 to -0.6‰) and a surprisingly heavy δ¹³C_CH4 (?20.9 to ?12.3‰). The difference between δ¹³C_CO2 and δ¹³C_CH4 (δ¹³C_CO2-CH4 ) for individual samples varies between 1.5‰ and 13.5‰. The δ¹³C_CO2 results show wide and overlapping ranges in the samples collected from the Precordillera, the Volcanic Arc (or Western Cordillera), the Altiplano, and the Eastern Cordillera. The widest ranges occur in the Eastern Cordillera (?15.0 to ?4.8‰) and the Altiplano (?20 to ?6‰). The δ¹³C_CO2 results for geothermal samples from the Volcanic Arc range between ?8.0‰ (Surire) and ?0.6‰ (Abra de Nappa), whereas δ¹³C_CO2 measured in gases collected from geothermal springs in the Precordillera range from ?10 to ?5‰.

The relationships between 3He/4He, δ¹³C_CO2 , and δ¹³C_CH4 are used to distinguish between crustal and mantle origins. The wide (21‰) range in the is interpreted to reflect contributions from different CO₂ sources that include organic and inorganic crustal and mantle carbon. Assuming isotopic equilibrium between coexisting methane and carbon dioxide, Δ¹³C_CO2-CH4 suggests very high equilibrium temperatures, in excess of 530°C, for some geothermal systems that also are characterized by a high (up to 63%) mantle-derived helium component.

δ¹³C_CH4 results suggest that methane has not formed by bacteriogenic processes or by thermal decomposition of organic matter, but rather abiogenically through the high-temperature reaction between H₂ and CO₂. The δ¹³C_CH4 results for the samples from the Volcanic Arc and from two CO₂-rich geothermal springs in the Altiplano (Coipasa-2 and Belen de Andamarca) are similar to those reported from hydrothermal fluids emitted from the East Pacific Rise (Welhan, 1988) and White Island, New Zealand (Hulston and McCabe, 1962), suggesting a mantle-derived carbon component in the methane.     

Assessing the potential for CO2 adsorption in a subbituminous coal,Huntly Coalfield,New Zealand,using small angle scattering techniques

Small angle scattering techniques (SAXS and SANS) have been used to investigate the microstructural properties of the subbituminous coals (R_max 0.42–0.45%) from the Huntly Coalfield, New Zealand. Samples were collected from the two thick (> 5 m) coal seams in the coalfield and have been analysed for methane and carbon dioxide sorption capacity, petrography, pore size distribution, specific surface area and porosity.Specific surface area (SSA) available for carbon dioxide adsorption, extrapolated to a probe size of 4 Å, ranged from 1.25 × 10⁶ cm^? 1 to 4.26 × 10⁶ cm^? 1 with total porosity varying from 16% to 25%. Porosity was found to be predominantly composed of microporosity, which contributed the majority of the available SSA. Although considerable variation was seen between samples, the results fit well with published rank trends.Gas holding capacity at the reservoir pressure (approximately 4 MPa) ranged from 2.63 to 4.18 m³/t for methane on a dry, ash-free basis (daf) and from 22.00 to 23.72 m³/t daf for carbon dioxide. The resulting ratio of CO₂:CH₄ ranged from 5.7 to 8.6, with an average of 6.7:1.Holding capacities for both methane and carbon dioxide on a dry ash free basis (daf) were found to be correlated with sample microporosity. However, holding capacities for the two gases on an as analysed (aa) basis (that is including mineral matter and moisture), showed no such correlation. Carbon dioxide (aa) does show a negative correlation with both specific surface area and microporosity. As the coals have low inorganic matter content, the reversal is thought to be related to moisture which is likely concentrated in the pore size range 12.5–125 Å. Methane holding capacity, both daf and aa, correlates with macroporosity, thus suggesting that the holding capacity of micropores is diminished by the presence of moisture in the pores.     

Coal petrographical characterization of the Mecsek bituminous coal basin, with special reference to the contact metamorphism of coal seams

The bituminous coals of the Mecsek Mountains were formed during the Early Lias and are of paralic origin. The limnic complex of the layers consists of sandstone, aleurite and coal, and the upper layer contains marl of marine origin. The 9–15 minable coal seams have a thickness of 1.2–14.0 m. The Mecsek Coal Field and the coal complex within it show a folded and fractured structure, and with regard to their mechanical behaviour, are strongly stressed.75–90% of the coal material is vitrinite, and 1–14% is inertinite. The quantity of liptinite is smaller than 9%. The coal rank is that of gas coal and fat coal with a reflectivity of 0.85–1.5%, respectively. The coal rank differences and variations according to zones are the consequence of forces of various magnitude that occurred in the course of orogenic movements.During the Early Cretaceous, there was some under-sea-bed volcanic activity in this field, the diabasic material of which appeared in the form of a bed vein along the coal seams, and this has exerted a strong metamorphic influence on the coal. It has resulted in thermo-contact alteration, i.e. in the appearance of natural coke and semicoke of various degrees of metamorphism. This alteration badly affected the quality and technological characteristics, especially the cokability of the coal.     

H2O-CH4-H2-CO2-CO-O2在高温、高压和高密度条件下的状态方程

为了计算高温，高压和高密度流体的热力学性质，提出了一个具有19个参数的维里型状态方程，其中参数与温度间的函数关系采用由Sutherland位能函数导出的维里系数近似式。除临界点附近以外，在已报道的pVT数据所覆盖的大部分超临界区域内，该方程均可适用。用该方程对H2O，CH4，H2，CO2，CO和O2等流体pVT关系的计算结果令人满意，其中pVT上限分别为：91-610GPa,1.6-11.0cm^3/mol,4000-5000K。计算体积的平均偏 小于0．8％，最大偏差小于5．4％。     

Effects of coal storage in air on physical and chemical properties of coal and on gas adsorption

This paper investigates changes in the high-volatile bituminous Lower Block Coal Member from Indiana owing to moisture availability and oxidation in air at ambient pressure and temperature over storage time. Specifically, it investigates changes in chemistry, in surface area, and pore structure, as well as changes in methane and carbon dioxide adsorption capacities. Our results document that the methane adsorption capacity increased by 40%, whereas CO₂ adsorption capacity increased by 18% during a 13-month time period. These changes in adsorption are accompanied by changes in chemistry and surface area of the coal.The observed changes in adsorption capacity indicate that special care must be taken when collecting samples and preserving coals until adsorption characteristics are measured in the laboratory. High-pressure isotherms from partially dried coal samples would likely cause overestimation of gas adsorption capacities, lead to a miscalculation of coal-bed methane prospects, and provide deceptively optimistic prognoses for recovery of coal-bed methane or capture of anthropogenic CO₂.