基于区块链技术电子健康档案信息系统设计的探讨

通过设计以区块链技术为基础的电子健康档案信息系统,说明如何应用区块链技术保证电子健康档案的安全性和完整性,保护个人隐私,促进电子健康档案的共享,从而实现促进电子健康档案的利用。

Research progress in hydrate-based technologies and processes in China:A review

Natural gas hydrate(NGH) is considered as an alternative energy resource in the future as it is proven to contain about 2 times carbon resources of those contained in the fossil energy on Earth. Gas hydrate technology is a new technology which can be extensively used in methane production from NGH, gas separation and purification, gas transportation, sea–water desalination, pipeline safety and phase change energy storage, etc. Since the 1980s, the gas hydrate technology has become a research hotspot worldwide because of its relatively economic and environmental friendly characteristics. China is a big energy consuming country with coal as a dominant energy.With the development of the society, energy shortage and environmental pollution are becoming great obstacles to the progress of the country. Therefore, in order to ensure the sustainable development of the society, it is of great significance to develop and utilize NGH and vigorously develop the gas hydrate technology. In this paper,the research advances in hydrate-based processes in China are comprehensively reviewed from different aspects,mainly including gas separation and purification, hydrate formation inhibition, sea–water desalination and methane exploitation from NGH by CH4–CO2 replacement. We are trying to show the relevant research in China, and at the same time, summarize the characteristics of the research and put forward the corresponding problems in a technical way.

Hydrate-based carbon dioxide capture from simulated integrated gasification combined cycle gas

The equilibrium hydrate formation conditions for CO2/H2 gas mixtures with different CO2 concentrations in 0.29 mol% TBAB aqueous solution are firstly measured.The results illustrate that the equilibrium hydrate formation pressure increases remarkably with the decrease of CO2 concentration in the gas mixture.Based on the phase equilibrium data,a three stages hydrate CO2 separation from integrated gasification combined cycle （IGCC） synthesis gas is investigated.Because the separation efficiency is quite low for the third hydrate separation,a hybrid CO2 separation process of two hydrate stages in conjunction with one chemical absorption process （absorption with MEA） is proposed and studied.The experimental results show H2 concentration in the final residual gas released from the three stages hydrate CO2 separation process was approximately 95.0 mol% while that released from the hybrid CO2 separation process was approximately 99.4 mol%.Thus,the hybrid process is possible to be a promising technology for the industrial application in the future.

Methane hydrate formation and dissociation behaviors in montmorillonite

The methane hydrate formation and the methane hydrate dissociation behaviors in montmorillonite are experimentally studied. Through the analyses of the microstructure characteristic, the study obtains the porous characteristic of montmorillonite. It is indicated that methane hydrate in montmorillonite forms the structure I (si) crystal. Meanwhile, molecular dynamics simulation is carried out to study the processes of the methane hydrate formation and the methane hydrate dissociation in montmorillonite. The microstructure and microscopic properties are analyzed. The methane hydrate formation and methane hydrate dissociation mechanisms in the montmorillonite nanopore and on the montmorillonite surface are expounded. Combining the experimental and simulating analyses, the results indicate the methane hydrate formation and methane hydrate dissociation processes have little influence upon the crystal structure of porous media from either micro- or macro-analysis. It is beneficial to the fundamental researches on the exploitation and security control technologies of natural gas hydrate in deep-sea sediments.

Advances of experimental study on gas production from synthetic hydrate reservoir in China

China has entered the area of new normal economy which requires the harmonious development of energy consumption,environmental protection and economic development.Natural gas hydrate is a potential clean energy with tremendous reserve in China.The successful field test of marine hydrate exploitation in South China Sea created a new record of the longest continuous gas production from natural gas hydrate.However,the corresponding fundamental research is still urgently needed in order to narrow the gap between field test and commercial production.This paper reviewed the latest advances of experimental study on gas production from hydrate reservoir in China.The experimental apparatus for investigating the performance of hydrate dissociation in China has developed from one dimensional to two dimensional and three dimensional.In addition,well configuration developed from one tube to complicated multi-well networks to satisfy the demand of different production models.Besides,diverse testing methods have been established.The reviewed papers preliminary discussed the mechanical properties and the sediment deformation situation during the process of hydrate dissociation.However,most reported articles only consider the physical factor,the coupled mechanism of physical and chemical factor for the mechanical properties of the sediment and the sand production problem should be studied further.

Decomposition behaviors of methane hydrate in porous media below the ice melting point by depressurization

The decomposition behaviors of methane hydrate below the ice melting point in porous media with different particle size and different pore size were studied.The silica gels with the particle size of 105–150μm,150–200μm and 300–450μm,and the mean pore diameters of 12.95 nm,17.96 nm and 33.20 nm were used in the experiments.Methane recovery and temperature change curves were determined for each experiment.The hydrate decomposition process in the experiments can be divided into the depressurization period and the isobaric period.The temperature in the system decreases quickly in the depressurization process with the hydrate decomposition and reaches the lowest point in the isobaric period.The hydrate decomposition in porous media below ice-melting point is very fast and no self-perseveration effect is observed.The hydrate decomposition is influenced both by the driving force and the initial hydrate saturation.In the experiments with the high hydrate saturation,the hydrate decomposition will stop when the pressure reaches the equilibrium dissociation pressure.The stable pressure in the experiment with high hydrate saturation exceeds the equilibrium dissociation pressure of bulk hydrate and increases with the decrease of the pore size.

Experimental investigation in the permeability of methane hydratebearing fine quartz sands

The permeability is one of the intrinsic parameters that determines the fluid flow in the porous media.The permeability in hydrate-bearing sediments affects the gas recovery and production of hydrate reservoirs significantly.The irregular permeability characteristics are challenging for fine-grained hydratebearing sediments.In this study,a series of experiments was conducted using an one-dimensional pressure vessel to investigate the hydrate formation characteristics and the permeability in hydratebearing fine quartz sands(volume weighted mean diameter was 36.695 mm).Hydrate saturations(0 e26%in volume)were controlled and calculated precisely based on the amount of injected water and gas,the system pressure and temperature.The results indicated that the hydrate nucleation induction period was completed during gas injection,and the average time of hydrate formation was within 500 min.The permeability of methane hydrate-bearing fine quartz sands was investigated by steady gas volume flow.For hydrate saturation lower than 13.94%,the hydrate mostly formed in grain-coating,the permeability reduction exponent calculated by Parallel Capillary,Kozeny Grain Coats and Simple Cubic Filling models were 2.00,2.10 and 1.74 respectively,and Simple Cubic Filling model was in accordance with the experimental data best.However,for hydrate saturation ranged from 13.94%to 25.91%,the permeability increased due to the flocculation structure formation of fine quartz sands and hydrate,which caused the increase of effective porosity.A new relationship among hydrate saturations,effective porosity,the ratio of permeability in the presence and the absence of hydrate was developed.This study developed the mathematical models for predicting the permeability with hydrate saturation in fine quartz sands,which could be valuable for understanding the characteristics of hydrate-bearing finegrained sediments.

水合物法分离低浓度煤层气中的甲烷

向模拟煤层气(13.11vol%CH4+86.89vol%N2)中添加5.8mol%四氢呋喃(THF)-0.03mol%十二烷基硫酸钠(SDS)促进剂溶液分离提纯煤层气,考察了压力、温度、反应时间对气体消耗量、反应速率、分解气中甲烷浓度、甲烷回收率和甲烷分离因子的影响,采用色谱分析法分别测定了CH4在剩余气相和分解气相中的浓度。结果表明,压力增加,CH4回收率增大,CH4分离因子增大,CH4分离效果越好;温度是影响甲烷分离因子的关键因素,温度降低,氮气和甲烷竞争进入水合物晶体中,导致水合物相中甲烷浓度降低;温度升高有利于提高水合物对甲烷的选择性。甲烷回收效率最高可达98.65%,分离因子最大为14.83。随反应时间增加,分解气中CH4浓度升高。

含盐蒙脱石中甲烷水合物的生成/分解特性及离子分布研究

目前,天然气水合物成藏和开采是新能源开发应用的热点,但海域沉积物中天然气水合物的形成/分解特性,及盐离子对水合物稳定性的影响等关键问题亟待解决。利用天然气水合物原位取样技术对甲烷水合物在含盐多孔介质中生成和分解过程进行原位扫描电镜(Scanning Electron Microscopy,SEM)测试和能谱分析(Energy Dispersive Spectrometry,EDS),系统研究了含0.5 mol/L NaCl溶液的蒙脱石中甲烷水合物生成、分解过程中形貌的变化及离子分布特征。研究发现水合物生成和分解过程元素分布发生明显改变,水合物生成的排盐效应使得NaCl在水合物颗粒与颗粒交结处以水合盐离子的形成存在,并且Na^(+)和Cl^(-)在蒙脱石表面分层排布。水合物生成后蒙脱石表面呈独立颗粒状,水合物分解后蒙脱石表面凹陷并形成微小的气体通道,并且水合物分解后蒙脱石的骨架堆积结构发生改变。研究得出水合物成核、生长、分解过程均在特定基元颗粒间是独立进行的,并且生长与分解过程与水合物晶胞结构有关。

盐离子对蒙脱石水化膨胀特性的影响

采用热失重法与经离心法、直接烘干法、冷冻干燥法结合对蒙脱石样品水含量进行测量,分析了NaCl浓度对蒙脱石中结合水与自由水含量的影响,探讨了蒙脱石中总含水量及结合水含量随NaCl溶液浓度变化的规律,研究了NaCl溶液中蒙脱石的水化膨胀特性及盐离子的抑制作用。结果表明,蒙脱石的水化膨胀受盐离子的抑制,盐离子的存在减小了渗透水化力,影响了水分子间的范德华力及水分子和蒙脱石表面间的氢键力和静电引力,总含水量随盐离子浓度增加而降低,盐离子浓度为0.2 mol/L时趋近最低值,样品膨胀程度由6.6缩小至1.6,盐离子对蒙脱石水化膨胀的抑制作用达峰值。盐离子浓度大于0.2 mol/L时,随盐离子浓度增加,自由水与结合水含量变化不明显。