Oxidative coupling of methane in a bubbling fluidized bed reactor

The oxidative coupling of methane to higher hydrocarbons (C₂₊) was studied in a bubbling fluidized bed reactor between 700°C and 820°C, and with partial pressures of methane from 40 to 70 kPa and of oxygen from 2 to 20 kPa; the total pressure was ca 100 kPa. CaO, Na₂CO₃/CaO and PbO/γ-Al₂O₃ were used as catalytic materials. C₂₊ selectivity depends markedly on temperature and oxygen partial pressure. The optimum temperature for maximizing C₂₊ selectivity varies between 720 and 800°C depending on the catalyst. Maximum C₂₊ selectivities were achieved at low oxygen and high methane partial pressures and amounted to 46% for CaO (T = 780°C; P_CH4 = 70 kPa; P_O2 = 5 kPa), 53% for Na₂CO₃/CaO (T = 760°C; P_CH4 = 60 kPa; P_O2 = 6 kPa) and 70% for PbO/γ-Al₂O₃ (T = 720°C; P_CH4 = 60 kPa; P_O2 = 5 kPa). Maximum yields were obtained at low methane-to-oxygen ratios; they amounted to 4.5% for CaO (T = 800°C; P_CH4 = 70 kPa; P_O2 = 12 kPa), 8.8% for Na₂CO₃/CaO (T = 820°C; P_CH4 = 60 kPa; P_O2 = 20 kPa) and 11.3% for PbO/γ-Al₂O₃ (T 2= 800°C; P_CH4 = 60 kPa; P_O2 = 20 kPa).     

利用“清洁发展机制”促进山西煤层气开发

山西省蕴藏着丰富的煤层气资源,合理利用煤层气资源不仅是对能源的补充,也对减轻温室效应起着重要作用。介绍了山西省正在进行的清洁发展机制CDM项目和CO2减排购买意向项目。分析看出,山西省目前井下瓦斯利用和地面煤层气利用可以产生良好的环境效益,煤层气减排市场可获得巨大的经济效益。指出了目前山西省CDM项目申报中存在的问题及未来发展的方向,分析了未来大规模开采利用煤层气所带来的CO2减排市场的巨大潜力。     

煤层气水合化的基础研究

自行设计制造了一套可用于煤层气水合物生成与分解的可视化实验系统,利用该实验系统研究了阴离子表面活性剂、非离子表面活性剂和多孔介质煤对煤层气水合物生成的影响,进行了煤层气水合物生成相平衡参数和分解热力学方面的研究。结果表明:表面活性剂的加入促进了水合物的生长,但水合物的生成情况与表面活性剂的种类和浓度有关;表面活性剂的加入有效地改变了水合物生成的热力学条件;水合物分解过程所需热量较多,证实了利用煤层气水合化技术预防煤矿煤与瓦斯突出以及进行煤层气固化储运的可行性。     

Evaluation of gas content of coalbed methane reservoirs with the aid of geophysical logging technology

The geophysical logging technology has been employed in connection with field and laboratory tests for coal reservoir evaluation in Huainan and Huaibei coalfields, China. The relationships between coalbed gas content of coal reservoir and characteristics of geophysical logs have been investigated by means of the combined analyses of experimental and geophysical logging data. Coalbed gas content of drilling core samples from coal seams was determined experimentally. The results, together with the log data obtained from geophysical logging technology, have been analyzed by using geological statistics, permitting correlation of the coalbed gas content to the log responses. The correlation developed in this study provides better understanding of the coal reservoir for coalbed methane exploration in given coalfields by an improved prediction of the coalbed gas content.     

煤制合成天然气现状及其发展

随着人们对天然气需求的快速增长,煤制天然气技术受到越来越多的关注,而煤制天然气的核心技术是甲烷化技术。对煤制合成天然气的国内外发展现状进行了介绍,并对甲烷化技术需要解决的关键技术及其发展提出了自己的见解。     

贵州省煤层气地质条件及开发利用现状

贵州煤层气资源丰富,笔者在分析了贵州省煤层气地质条件的基础上,得出影响煤层气开发的主要因素是复杂的地形条件;煤层气开采成本较高,且成品价格较低;煤层气与煤炭矿权没有分离是导致煤层气不能有效利用的主要原因,解决这些问题的主要措施是尝试煤层气的井下液化,国家重点扶持大型企业等。     

地球物理技术在煤层气勘探中的应用

煤层气的勘探对于优化能源结构、保障煤矿安全、减少温室气体排放等具有重要意义。基于煤储层的方位各向异性和双相介质特征,方位AVO、转换横波法和AVO等地震勘探技术能够对煤层气富集区做出有效预测。测井技术具有方法种类多、分辨率高等特点,在煤层气储层识别和储层参数定量解释方面取得了较好的应用效果。开展地震技术和测井技术的综合利用是今后煤层气勘探技术的发展方向。     

Synthesis gas formation by direct oxidation of methane over Rh monoliths

The production of H₂ and CO by catalytic partial oxidation of CH₄ in air or O₂ at atmospheric pressure has been examined over Rh-coated monoliths at residence times between 10^–4 and 10^–2 s and compared to previously reported results for Pt-coated monoliths. Using O₂, selectivities for H₂ ( ) as high as 90% and CO selectivities (S _CO) of 96% can be obtained with Rh catalysts. With room temperature feeds using air, Rh catalysts give of about 70% compared to only about 40% for Pt catalysts. The optimal selectivities for either Pt or Rh can be improved by increasing the adiabatic reaction temperature by preheating the reactant gases or using O₂ instead of air. The superiority of Rh over Pt for H₂ generation can be explained by a methane pyrolysis surface reaction mechanism of oxidation at high temperatures on these noble metals. Because of the higher activation energy for OH formation on Rh (20 kcal/mol) than on Pt (2.5 kcal/mol), H adatoms are more likely to combine and desorb as H₂ than on Pt, on which the O+ H OH reaction is much faster.This research was partially supported by DOE under Grant No. DE-FG02-88ER13878-AO2.     

Catalytic combustion of natural gas as the role of on-site heat supply in rapid catalytic CO2---H2O reforming of methane

Development in highly active catalysts for the reforming of methane with H₂O, CO₂, and H₂O+CO₂, and partial oxidation of methane was conducted to produce hydrogen with high reaction rates. A Ni-based three-component catalyst such as Ni---La₂O₃---Ru or Ni---Ce₂O₃---Pt supported on alumina wash-coated ceramic fiber in a plate shape was very suitable for both reactions. The catalyst composition was set at 10 wt.-% Ni, 5.6 wt.-% La₂0₃, and 0.57 wt.-% Ru for example, or molar ratios of these components were 1:0.2:0.03. Even with such a low concentration, the precious metal enhanced the reaction rate markedly, and this synergistic effect was ascribed to the hydrogen spillover effect through the part of precious metal and it resulted in a more reduced surface of the main catalyst component. In particular, a marked enhancement in the reaction rate of CO₂-reforming of methane was observed by the modification of a low concentration Rh to the Ni---Ce₂0₃---Pt catalyst. Very high space-time yields of H₂ (i.e., 8300 mol/1 h in partial oxidation of methane at 600°C with a methane conversion of 37.5%, and 3585 mol/1 h in CO₂reforming of methane at 600°C with a methane conversion of 58%) were realized in those reactions. By combining the catalytic combustion reaction, methane conversion to syngas was markedly enhanced, and even with a very short contact time (10 ms) the conversion of methane increased more than that at 50 ms. The space-time yield of hydrogen amounted to 2,780 mol/1 h with a methane conversion of 90% at 700°C. Furthermore, in a reaction of CH₄---CO₂---H₂O---O₂ on the four components catalyst, an extraordinarily high space-time yield of hydrogen, 12 190 mol/1 h, could be realized under the conditions of very high space velocity (5 ms).     

煤层气开发利用的制约因素及对策

介绍了中国煤层气资源状况及开发利用现状,在此基础上分析了制约中国煤层气资源开发利用的不利因素,并针对这些制约因素提出了解决对策,为加快中国煤层气开发利用提供了思路。     

大型煤化工企业制冷工艺选择

煤制天然气项目对天然气的净化是一个较大的问题,在这其中如何给低温甲醇洗、甲烷化工序提供冷量是一个关键的因素,对投资额的大小、投产后的经济效益有较大的影响,混合制冷方法是几种制冷手段中比较合适的手段     

Cu/γ-Al2O3 catalyst for the combustion of methane in a fluidized bed reactor

The applicability of a catalyst based on copper dispersed on γ-Al₂O₃ spheres (1 mm diameter) for fluidized bed catalytic combustion of methane has been assessed. Catalyst properties have been determined by physico-chemical characterization techniques and fixed bed activity tests revealing the presence of a surface CuAl₂O₄ spinel phase, still active and stable in methane combustion after repeated thermal ageing treatments at 800 °C. Methane catalytic combustion experiments have been performed in a 100 mm premixed fluidized bed reactor under lean conditions (0.15–3% inlet methane concentration), showing that complete CH₄ conversion can be attained below 700 °C in a fluidized bed of 1 mm solids with a gas superficial velocity about twice the incipient fluidization velocity.     

利用煤层气发展山西化工

煤层气是近30年开始开发与应用的新能源,是非常规天然气,其主要成分为甲烷,山西省地下煤层气可彩资源约9000亿m^3,按热值换算相当于11.7亿t煤炭。利用煤层气制造合成气发展化学工业,成本低,污染轻。     

晋城矿区煤层气发电现状及规划

晋城矿区赋有丰富的煤层气资源 ,为充分利用这部分煤层气资源 ,晋城无烟煤矿业集团利用美国的打钻、压裂、排采技术实施煤层气开发示范工程 ,经潘庄、寺河两矿煤层初步发电试验 ,取得成功 ,2 0 0 2年初运转的 1 1× 1 0 4kW发电示范工程 ,取得良好的经济效益 ,为后续煤层气资源利用积累了宝贵的经验。     

Devolatilization of coals of northeastern India in inert atmosphere and in air under fluidized bed conditions

Devolatilization of five coals having volatile matter in the range of 31 to 41% was studied in argon and in air under fluidized bed conditions. The diameter of the coal particles varied between 4 and 9.5 mm. The variation of devolatilization time with particle diameter was expressed by the correlation, t_v = Ad_vⁿ. The superficial gas velocity was found to have a significant effect on the rate of devolatilization. The devolatilization rate increased with the increase in the oxygen concentration in the fluidizing gas. The correlations developed in this study fitted the mass versus time profiles of the coal particles satisfactorily. The same correlations were found to be appropriate for predicting devolatilization of a batch of coal particles. The correlations developed in the present study will be useful for the design of fluidized bed combustors.     

煤层气发电与机型选择

煤层气作为一种洁净能源进行发电,可根据开采气体的浓度,选择燃气轮机或燃气内燃机,进行热电联产具有很好的效益。     

Enrichment of coal‐bed methane by PSA complemented with CO2 displacement

A PSA cycle complemented with CO₂ displacement was studied for enriching coal‐bed methane (CBM). The column was first pressurized to the adsorption pressure with feed gas, and then N₂ was produced at column top in step 2. The feed gas switched to CO₂ at the end of step 2, and the adsorbed CH₄ was displaced and pushed to column top by CO₂ becoming the second column‐top product in step 3. The CO₂ stream was shut off before it broke through the sorption bed. Then bed regeneration followed. A series of CH₄/N₂ mixtures containing 17.62 to 51.33% CH₄ was used for feed gas. It was experimentally shown that the product concentration was higher than 90%, and methane recovery was higher than 98% even for the feed of low‐methane concentration. Displacement at ambient pressure was shown more efficient than the displacement at adsorption pressure for the enrichment. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Modeling and simulation of simulated countercurrent moving bed chromatographic reactor for oxidative coupling of methane

Oxidative coupling of methane (OCM) is a reaction of industrial importance but per pass equilibrium conversion and product yield in a single reaction column is severely low. The simulated countercurrent moving bed chromatographic reactor (SCMCR) has been reported to significantly improve the methane conversion and C₂-product yield. This paper addresses the mathematical modeling of a five section SCMCR for OCM, which is particularly important for understanding the operation of this SCMCR system. In order to obtain the various process parameters, a realistic and rigorous kinetics was adopted in reactors for OCM and subsequently a kinetic model was developed which can best describe the associated kinetics of OCM in SCMCR. Adsorption isotherm parameters were then derived based on the experimental breakthrough curves acquired using single adsorption column. The proposed mathematical model demonstrated extremely good predictions of the experimental results. Finally, effects of operating parameters, such as switching time, methane/oxygen feed ratio, raffinate flow rate, eluent flow rate, etc., on the behavior of the SCMCR were studied systematically.     

煤化度对煤层气成藏特性影响规律的研究

综述了煤层气的成因类型和成气过程的研究现状,说明生物成因和热成因是煤层气的2种主要成因类型,且煤层气生成过程以热成因为主,生物成因为辅。通过分析不同煤化度煤层气的生成过程,说明在整个煤化作用过程中煤层气的生成大致经历了4个阶段,即由植物遗体转化为泥炭阶段、褐煤转型阶段、长焰煤～瘦煤转化阶段以及贫煤～无烟煤阶段。从煤化度角度阐述了不同煤化度煤层气的贮藏特性,即不同煤化度煤层气存在较大差异,特别是不同煤层气吸附、解吸特征的差异影响了其吸附成藏、解吸、渗流及产出的整个过程;煤吸附CH4的能力随着煤化度的增加呈现先急剧增加后缓慢减小的趋势。最后分析了不同煤化度煤层气存在成藏差异的原因,说明煤化学结构、煤物理结构以及成煤过程中地质条件的差异是导致不同煤化度煤层气富集成藏差异性的主要原因。