基于水合物技术的沼气配送工艺研究

以十二烷基硫酸钠(SDS)作为促进剂,开展水合物技术配送沼气的工艺研究,考察了沼气水合物的制备、存储稳定性及分解释放等。结果表明,以浓度为0.03%(v/v)的SDS溶液为工作液,沼气水合物具有接近理论值的储气效果,单位储气量可达170 V/V,制备水合物的最优条件为温度1~3℃,压力3.0~3.5 MPa。沼气水合物在略低于0℃的条件下显示出良好的稳定性。温度越低,压力越高,越有利于沼气水合物的存储,但储运成本增加;在短距离配送中,温度略低于0℃的封闭体系即可满足储运要求。常压敞开条件下,沼气水合物可迅速分解释放,25℃时的释放时间为12 min。沼气水合物分解后的工作液可以回用,且对水合物的制备有促进作用。     

基于层次分析法和熵权法的中小型沼气工程净化提纯技术筛选

文章构建了3层次13指标的沼气提纯技术综合评价体系,并运用层次分析法和熵权法从技术成熟度、产品气性能、设备适应性、环境指标和经济指标5个方面对13个指标进行了权重排序,得出最重要的3项指标分别为产品气纯度、甲烷回收率和对不同来源沼气的适应性,其权重分别为0.179 6,0.111 1和0.105 4。在该评价体系的基础上,采用模糊综合评价法对5种常用沼气提纯技术进行适合中小型沼气工程提纯系统应用的排序,得出其顺序为膜分离法、变压吸附法、化学吸收法、物理吸收法、深冷分离法。层次分析法和熵权法的综合使用,减弱了层次分析法的主观性影响,避免了熵权法偏离实际生产的可能,为沼气提纯技术的筛选提供了一种科学的方法。     

沼气水洗提纯吸收塔的体积吸收系数研究

文章以设计处理量为25 m~3/h的沼气压力水洗提纯装置为实验对象,研究了温度、压力、液气比、进气量和浓度等参数对提纯气CO_2浓度和吸收塔平均体积吸收系数KYa的影响,并提出了优化的操作参数条件。沼气提纯过程具有高浓度和高液气比的特点,文章分析了高CO_2浓度下的KYa理论计算公式,建立了以液、气相速度比UL/UG为基础的KYa数学模型,该模型和实验数据的偏差为-22%～17%。该模型既强调了沼气提纯过程具有高液气比的特点,又为沼气水洗提纯技术提供了合理的吸收性能分析经验公式,具有重要的工程价值。     

生物沼气的应用与提纯

沼气作为一种洁净的能源,除用于传统的供热外,现在主要用于发电及作为车用压缩天然气或管道天然气.沼气的提纯主要包括脱硫、脱水、脱氧、脱碳等过程.变压吸附法脱碳与其他脱碳方法相比,无论从能耗还是工艺都具有很大优势,该方法用于沼气的脱碳具有广阔前景.     

天然气水合物实验检测与分析技术

天然气水合物在资源和环境上的重要性,已引起世界各国的高度关注。目前实验室采用多种检测及分析技术对天然气水合物进行研究,取得了一系列研究成果。光学检测可应用于非沉积物的水合物实验;电阻法将在研究水合物成核机理中发挥重要作用;温压法、超声检测、TDR及CT技术也可有效地检测水合物的生成与分解过程;衍射法、拉曼光谱及核磁共振可用于确定水合物晶体结构;DSC则为研究水合物的分解行为提供了新思路。     

中国石油大学(北京)新能源研究院

<正> 中国石油大学(北京)新能源研究中心已承担国家科技部、农业部、住建部、北京市科委、教委和发改委多项沼气高值利用课题,并己成功完成北京市安定垃圾填埋场垃圾沼气净化纯化高值利用工业开发,正在进行3项沼气生产压缩天然气(CNG)工业示范,1项高浓度H2S沼气脱硫发电工业示范。可提供以下系列成介技术及工业没计沼气生产高值燃气系列技术利用沼气提纯生产天然气特别是     

湿法脱硫技术在沼气内燃机上的应用

沼气作为生物质能源中的一种,已广泛用于内燃机电站发电.但是沼气中H2S对内燃机的腐蚀,严重制约了内燃机的可靠使用.本文通过湿法脱硫技术对某淀粉厂消化沼气进行处理,并对脱硫前后的内燃机部件消耗进行了比较,证明了该方法的有效性和可行性,脱硫后的沼气中硫化氢浓度低于200mg/Nm3,对沼气内燃机的应用具有良好的保护作用.     

全密闭旋涡气泵的设计及用于沼气输送的试验研究

提出了一种可用于沼气等易燃气体加压输送的全密闭旋涡气泵的结构设计,并制造了模型样机。组装了燃气输送测试试验台,以进行其用于沼气输送的可行性验证试验和对其进行性能测试。900 h以上的试验运行表明,全密闭旋涡气泵完全适合作为我国村镇沼气加压输送设备使用。     

大中型沼气工程高压水洗提纯工艺的模拟

沼气高压水洗提纯工艺在我国尚处于起步阶段。针对国外水洗工艺规模适用于250 m3/h以上超大型工程,而我国大中型沼气工程在50 m3/h左右,缺乏合适水洗工艺的现状,文章基于CH4-CO2-H2S-H2O体系ELECNRTL热力学模型,构建了高压水洗全工艺流程,并对工艺关键参数,包括沼气处理量、补水量、沼气中甲烷浓度和H2S含量等对工艺的影响进行分析,在此基础上给出了水洗吸收塔和解吸塔参数。为发展我国沼气高压水洗工艺奠定了理论基础。     

中国农村户用沼气生产及其影响因素分析

对我国农村沼气生产情况进行了分析,认为我国农村沼气生产在取得较快发展的同时,存在较大的地区差异.文中采用面板数据对农村沼气生产影响因素进行分析,指出我国农村沼气生产明显受到该地区大牲畜存栏数量、平均温度、农户收入水平以及制度和技术进步因素的影响,而农户人均受教育程度和沼气的替代能源价格等因素对沼气生产的影响并不明显.     

多孔介质中甲烷水合物的生成特性研究进展

天然气水合物是一种清洁高效的能源,常常在自然界中的海底沉积物多孔介质孔隙中生成,同时水合物在工业上还能与多孔介质材料一起作为储存及分离气体的一种方式,因此开采利用水合物以及发挥水合物工业技术的前提都跟多孔介质有莫大的关系,对多孔介质中天然气水合物生成特性的研究进行总结与分析具有非常重要的意义。本文总结分析了国内外关于不同类型多孔介质中甲烷水合物的生成过程及特性的研究文献,将多孔介质根据其孔径大小进行划分。结果显示,在微孔介质中,甲烷水合物的生成侧重于气体的存储及运输方面;在介孔介质中,甲烷水合物的生成动力学受孔径影响较大;在大孔的沉积物中,甲烷水合物的生成及分布的机理性研究仍比较缺乏。因此,需要进一步的研究来丰富甲烷水合物在多孔介质中的生成动力学理论,本文将在文献调研的基础上为今后的研究方向提出一些展望和思路。     

生物质气化技术面临的挑战及技术选择

生物质气化可实现低品位生物质能的深层次利用,不同地区、不同行业有不同的能源需求和产业结构,应合理选择生物质气化技术。固定床气化技术针对的是中小规模应用,该技术存在的问题包括焦油含量高、规模小、机械化和自动化程度较低、发电效率低等。流化床气化技术针对的是中等及以上规模应用,目前需要解决的问题是热效率低,发电效率低,需要开发高气化效率和无焦油的燃气型气化炉、低热值燃气轮机、高效燃气净化系统,以便采用BIGCC技术。沼气技术是一项生物质综合高效清洁利用的多联产工艺,目前急需开发高效高浓度厌氧消化的沼气发酵工艺和配套的集成设备,培育和筛选高效沼气发酵微生物菌群,简化沼气净化工序,解决沼液、沼渣的利用难题等。生物质快速热解技术是一种高温处理过程,其最大的优点是产物生物油易于储存运输,不存在产品规模和消费的地域限制问题。从工艺特点、经济效益和规模化生产来看,沼气技术更适合处理高含水的养殖业粪便,快速热解技术更适合农作物秸秆的规模化转化,燃气型气化技术更适合社区生活垃圾和农林产品加工废弃物的处理。     

Adsorption technology for the storage of natural gas and biomethane from biogas

As natural gas, biogas has been used for nobler purposes in recent years, such as the use of purified biogas (biomethane) in the transport sector. Currently, natural gas storage for use in transportation is accomplished primarily through compressed natural gas (CNG) technologies and liquefied natural gas (LNG), which require large amounts of energy. In recent years, the storage technology of absorbed natural gas (ANG) on porous materials has been studied, fundamentally highlighted by reduced energy use and increased safety in the transport of gaseous fuel. In this sense, the present study aimed to gather information about the main adsorbent materials which are being studied and the conditions normally employed in surveys that use ANG technology, as well as pointing out the main challenges for the storage of biogas in the adsorbed form at low pressures and room temperature in an attempt to meet the target of 180 V/V established by Department of Energy. Researchers reported high storage capacities in moderate conditions of temperature and pressure; however, the biggest challenge of the research involving methane adsorbed is also achieving high rates of desorption with the lowest possible energy expenditure. Copyright © 2016 John Wiley & Sons, Ltd.     

Economics and greenhouse gas balance of biogas use systems in the Finnish transportation sector

Energy decisions play an essential role in reducing greenhouse gas (GHG) emissions in the transportation sector. Biogas is a renewable energy source and can be used as an energy source for gas-operated cars or for electric cars. This paper compares different ways to use biogas, which is produced on a medium scale anaerobic digestion plants, as an energy source for transportation. The research is conducted from an economic and environmental point of view, and the option to deliver upgraded biogas via a natural gas grid is taken into account. Different processes for the use of biogas for transportation purposes are compared using life cycle assessment (LCA) methods in the Finnish operational environment. It seems that the most economical way is to use biogas in gas-operated cars due to the high price of methane for vehicle fuel use. A new feed-in tariff for electricity produced with biogas will, however, have highly positive economic effects on electricity production from biogas. From the environmental point of view, the highest CO₂ reductions are gained when biogas is used in gas-operated cars or in CHP plants for power and heat production. During the transition stage, it might be reasonable to use biogas in gas-operated cars and most importantly in heavy vehicles to reduce GHG and local pollutants rapidly. If biogas production is located near a natural gas grid, the biogas can be delivered effectively via the natural gas grid. The use of biogas in gas-operated cars is an effective way to reduce carbon dioxide significantly in the transportation sector.     

储气用天然气水合物强化制备的研究进展

天然气是一种清洁、高效的能源，未来的需求量呈增长趋势。以水合物方式储运天然气与传统的储运天然气方式相比，具有经济、安全等优势。采用水合物进行天然气的固态运输具有良好的开发前景。介绍了天然气水合物强化制备的几种方式，有搅拌法、喷雾法、喷射法、鼓泡法，还有加入添加剂以及外场等方式，通过阐述各种方式的工作原理说明这些强化方式可以加快反应速率和增加天然气水合物的储气密度。     

一种新型天然气储存技术及其应用前景

天然气水合物（NGH）是在低温高压的条件下由水和天然气形成的笼形结晶化合物。天然气水合物储气技术是一种新型的天然气储气技术，具有能量密度高、安全可靠、费用低等优点。文章介绍了天然气水合物的制备、储气性能以及应用前景。     

Investigations on the formation kinetics of semiclathrate hydrate of methane in an aqueous solution of tetra-n-butyl ammonium bromide and sodium dodecyl sulfate in porous media

Natural gas hydrate is considered to be an attractive sustainable energy resource for the world. Hydrate as a technology can be of immense importance for various industrial processes, such as multicomponent natural gas separation, gas storage and transportation, and carbon dioxide capture from flue gases and sequestration. A variety of hydrate additives, which includes promoters (thermodynamics and kinetics) and porous media, are being researched to improve the hydrate formation kinetics. However, studies involving the combinations of these are rare in the open literature. In this work, the formation kinetics of methane hydrate/semiclathrate hydrate using tetra-n-butyl ammonium bromide (TBAB) and sodium dodecyl sulfate (SDS) aqueous solutions at various concentrations in a porous medium containing silica sand at initial hydrate formation pressures (7.5 and 5.5 MPa) and temperatures (273.65 and 276.15 K) have been investigated. All the experiments were conducted using 75% water saturation. Various kinetics parameters, such as gas uptake, gas-to-hydrate conversion, and induction time, have been reported. It was found that the combination of TBAB+ SDS showed favorable hydrate formation kinetics in porous media than the TBAB system. This work provides information for further studies involving semiclathrate hydrate applications for various industrial processes.     

天然气水合物开采技术——C02-cH4置换法最新研究进展

C02-CH4置换技术作为-种既可生产CH4又能减少CO2排放的天然气水合物开采方法,近20年来得到了广泛深人的研究。该技术的优势是：当温度低于10℃,CO2水合物较CH4水合物在热力学上更为稳定,两者的置换反应在理论上是自发的,CO2水合物的形成有助于保持气体水合物藏的地质力学稳定性。但该方法也有缺点,CH4水合物周围CO2水合物的形成限制了CH4水合物的分解,孔隙空间中形成的次生水合物会堵塞可用于气体置换的渗透性通道．因此并不是所有的CH4都能被CO。所替换。近年来业界在CO2-CH4置换技术的室内实验、数值模拟和现场试验等方面取得了-些进展。未来主要的研究方向应是全面了解不同生产策略下CO2-CH4-CH4水合物-CO2水合物-水／卤水系统的行为和储层条件;开展更多的现场规模生产项目;数值模拟中需要考虑更多的组分和相态,了解和考虑更多的过程和机理,并结合室内和现场试验结果,考虑地质特性的影响;更深入地了解CO2和N2对CH4的驱替。     

Enhancement of methane hydrate formation using a mixture of tetrahydrofuran and oxidized multi‐wall carbon nanotubes

Methane hydrate is a kind of gas hydrate formed by physical binding between water molecules and methane gas, which is captured in the cavities of water molecules under a specific temperature and pressure. Pure methane hydrate of 1 m³ can be decomposed into methane gas of 172 m³ and water of 0.8 m³ at standard conditions. Methane hydrate has many practical applications such as separation processes, natural gas storage transportation, and carbon dioxide sequestration. For the industrial utilization of this substance, it is essential to find a rapid method of manufacturing it. This work studies the formation of methane hydrates by using tetrahydrofuran (THF) and oxidized carbon nanotubes (OMWCNTs) by testing different fluid mixtures of THF and carbon nanotubes. The results show that when the mixed fluid contained THF, the OMWCNTs showed the gas consumption 5.2 times that of distilled water at 3.4 K subcooling. Also, THF's effects as a thermodynamic phase equilibrium promoter were preserved when it was used with OMWCNTs. Therefore, it can be expected that when OMWCNTs are used with an aqueous mixture of THF, both the favorable phase equilibrium of THF and the high gas consumption of the carbon nanotubes can be obtained. Copyright © 2013 John Wiley & Sons, Ltd.     

Mechanism and control factors of hydrate plugging in multiphase liquid-rich pipeline flow systems: A review

There is nothing illogical in the concept that hydrates are easily formed in oil and gas pipelines owing to the low-temperature and high-pressure environment, although requiring the cooperation of flow rate, water content, gas-liquid ratio, and other specific factors. Therefore, hydrate plugging is a major concern for the hydrate slurry pipeline transportation technology. In order to further examine potential mechanisms underlying these processes, the present paper listed and analyzed the significant research efforts specializing in the mechanisms of hydrate blockages in the liquid-rich system, including oil-based, water-based, and partially dispersed systems (PD systems), in gathering and transportation pipelines. In addition, it summarized the influences of fluid flow and water content on the risk of hydrate blockage and discussed. In general, flow rate was implicated in the regulation of blockage risk through its characteristic to affect sedimentation tendencies and flow patterns. Increasing water content can potentiate the growth of hydrates and change the oil-water dispersion degree, which causes a transition from completely dispersed systems to PD systems with a higher risk of clogging. Reasons of diversity of hydrate plugging mechanism in oil-based system ought to be studied in-depth by combining the discrepancy of water content and the microscopic characteristics of hydrate particles. At present, it is increasingly necessary to expand the application of the hydrate blockage formation prediction model in order to ensure that hydrate slurry mixed transportation technology can be more maturely applied to the natural gas industry transportation field.