超疏水蒸馏膜的功能改性研究进展

膜蒸馏技术因具有操作压力低、温差小、蒸馏液纯净、脱盐率高、可直接分离出结晶产物等优点而备受关注。但缺乏优异疏水性能的蒸馏膜是限制其应用的一个重要因素。迄今为止,科研人员在膜材料的疏水理论研究与超疏水蒸馏膜的功能改性方面开展了大量工作,研究者通过向膜面引入含硅或碳的纳米颗粒来提高膜面粗糙度,选用含氟的改性添加剂降低表面能,采用不同溶剂分散原材料并选择不同的成膜方式,使制备出的蒸馏膜疏水性能有了大幅度提高。本文归纳总结了近年来超疏水蒸馏膜功能改性方法的研究进展,并对改性效果进行了对比分析。分类研究结果表明,表面涂覆法适用于不同类型的基膜,可实现对膜骨架和膜表面的同时改性,既增大膜通量又提高膜的抗污染性能,操作简单,可以应用于大规模生产。与涂覆法相比,静电纺丝掺杂法改性的膜可以最大程度地保持稳定性,在提高耐透水性的同时可以减小改性物质对通量的影响,但其应用范围受到基膜的限制。化学沉积法可获得有梯度的沉积物或混合镀层,相比于涂覆法更容易控制涂层的组成和厚度,可进行更加精准的膜表面改性过程。等离子体等非传统方法多为几种方法的联用,从改性剂材料、操作过程、操作条件等方面均为蒸馏膜的改性开辟了新方向。本文分类分析了不同改性方法采用的疏水添加剂、分散剂、操作方法与操作条件,并对比了不同方法改性后的膜通量、孔隙率、脱盐率、过滤周期等指标,结合过滤方式评价了不同改性方法的优缺点,展望了超疏水改性蒸馏膜商业化应用面临的问题及发展前景,旨在为开发成本低廉、操作简单、膜通量高、抗污染能力强的超疏水蒸馏膜提供参考。

疏水膜、疏水性能评价及其自发脱水干燥

介绍了多孔疏水膜的定义、临界润湿值的概念、疏水膜的透水压力值和临界润湿值测试方法。区别于通常的外力加热等方法,介绍了利用疏水膜材料自身特性来实现疏水膜干燥的两种疏水膜自脱水干燥的方法.一种方法是控制膜污染润湿进程,当膜孔被润湿的深度小于该疏水膜材料的临界润湿值时,通过膜清洗实现疏水膜的自发脱水干燥.另一种方法是构建亲疏水双层复合疏水膜,当膜运行至产水电导率明显上升时,停机清洗,利用亲水材料与水之间的吸引力大于疏水材料与水之间的吸引力的特性使疏水膜孔自发脱水干燥.

反渗透系统中的通量失衡现象与通量均衡工艺

指出了膜系统通量严重失衡的原因与危害,提出了膜元件透水压力的概念,分析了透水压力、给水盐量及给水温度与通量失衡之间的关系。描述了淡水背压、段间加压与分段配膜等三项常规通量均衡工艺以及元件位置优化、能回加压透平与梯级加压水泵等三项特殊通量均衡工艺,并较为全面地分析了反渗透系统中的通量失衡现象与各项通量均衡工艺。

控水压裂工艺方法及效果分析

针对不同储层的渗流特征以及压裂裂缝扩展规律,探讨油井控水压裂技术实施效果。分别通过选择性控水支撑剂、透油阻水压裂液、人工隔离层等工艺进行现场先导实验,观察分析控水工艺使用前后含水率与产油量的情况。根据不同高含水井区的工程地质特征,提出控水压裂工艺优化选择方案。

阴极扩散层结构对空气自呼吸式DMFC性能的影响

采用三种碳粉制备了阴极扩散层,对其表面形貌、孔隙率、透水压和透气性进行了表征,并将其应用于空气自呼吸式直接甲醇燃料电池。结果表明,与Vulcan XC-72R和Black Pearls2000碳粉所制备的阴极扩散层相比较,采用Printex XE-2碳粉制备的阴极扩散层具有较高的孔隙率和适中的孔径,具有较高的透气性和较低的透水压,有利于阴极气体扩散和水的排出,提高了空气自呼吸式直接甲醇燃料电池的性能和极限电流密度。

膜式氧合器中聚砜非对称膜的制备及表征

通过L-S相转化法制备了膜式氧合器的聚砜不对称膜,并对其性能进行表征.制膜实验结果表明,随着铸膜液浓度的增加,氧气和二氧化碳渗透通量减小,临界透水压力增大,而湿膜的预挥发时间越长,膜的通量越小,但是临界透水压力变化不大,因此优化的铸膜液浓度为15%和预挥发时间为5s.此外针对膜式氧合器的气液传输测试结果表明,当牛血流速为5L/min时,氧气和二氧化碳通过膜的传输速率分别达到163mL/min和148mL/min,可以满足膜式氧合器气体交换传输能力的要求.

扩散层微观结构对DMFC阳极传质及性能的影响

通过调变微孔层中的PTFE含量,结合亲/憎水孔孔隙率、表面性貌等表征考察了扩散层的微观结构对其透水、透气性能的影响,并进一步研究了该阳极扩散层微观结构对DMFC阳极侧气、液传质和单池性能的影响。结果表明,当微孔层中PTFE含量为30%时,扩散层表面具有丰富且均匀的微米级大孔,亲/憎水孔孔隙率比例适中(3︰4),透水压和气体渗透系数大小合适(分别为0.01075MPa和2.743×10-12m2·s-1);由该扩散层组装的单电池甲醇渗透量较小,单位时间内阳极侧排出的CO2量较多,阳极侧气、液综合传质性能最好,电池性能最优,在80℃、常压、3倍空气剂量比时,最高比功率达90mW/cm2。

Numerical simulation of dynamic pore pressure in asphalt pavement

For studying the driving role of dynamic pressure in water-induced damage of asphalt pavement, based on the fast Lagrangian finite difference method and Biot dynamic consolidation theory, fluid-solid coupling analysis of the pavement is conducted considering asphalt mixtures as porous media. Results reveal that the development and dissipation of the dynamic pore pressure are coinstantaneous and this makes both the positive and negative dynamic pore pressure and seepage force alternate with time. Repetitive hydrodynamic pumping and sucking during moisture damage is proved. The dynamic pore pressure increases with vehicle velocity. Effective stress and deflection of pavement decrease due to the dynamic pore water pressure. However, the emulsification and replacement of the asphalt membrane by water are accelerated. The maximum dynamic pore pressure occurs at the bottom of the surface course. So it is suggested that a drain course should be set up to change the draining condition from single-sided drain to a two-sided drain, and thus moisture damage can be effectively limited.

有机-无机复合型防水剂对砂浆性能的影响及机理分析

研究了不同掺量有机-无机复合型防水剂对基准砂浆抗渗性能和吸水性能的影响,以及在最优掺量下对不同强度等级抹灰砂浆力学性能和抗渗性能的影响,利用压汞试验和扫描电镜等分析了砂浆的防水性能提高的作用机理。结果表明:防水剂的最优掺量为5%,对应的基准砂浆吸水量比为49%、透水压力比为325%,同时抹灰砂浆的抗压强度比均大于105%、抗渗性能至少提高2个等级。机理分析表明,防水剂主要是促进了更多的水化硅酸钙凝胶体和Ca(OH)_(2)的生成,填充材料的孔隙,增大了基材的密实度,进而显著降低孔隙率、窄化了孔结构,在改善砂浆防水性能的同时力学性能也得到显著提高。

基准砂浆抗渗性能检测结果稳定性的探讨和研究

在实验室条件下,通过调整砂浆配合比,采用不同的密实方法、养护手段,掺入外加剂等方式来制备多组基准砂浆试件,并测试其养护至7 d龄期时的透水压力值,目的是寻找合适的配比和方法,使基准砂浆的透水压力值能稳定在0.3～0.5 MPa,以满足各种防水材料性能检测的要求。结果表明,水泥:砂:水:纤维素醚=360:1 350:220:0.5,采用手工插捣密实,浸水养护或入养护箱养护的砂浆试件抗渗性能均较为稳定,且满足检测要求。

Chloride ion penetration into concrete under hydraulic pressure

The lining concrete of subsea tunnel services under combined hydraulic pressure, mechanical and environmental loads. The chloride ion and water penetrations into concrete under hydraulic pressure were investigated. The experimental results indicate that the water penetration depth, chloride ion transportation depth, and the concentration of chloride ion ingression into concrete increase with raised hydraulic pressure and hold press period. But the chloride ion transportation velocity is only 53% of that of water when concrete specimens are under hydraulic pressure. The chloride transportation coefficient of concrete decreases with hold press period as power function. And that would increase 500% 600% in chloride transportation coefficient when the hydraulic pressure increases from 0 to 1.2 MPa. The hydraulic pressure also decreases the bound chloride ion of concrete to about zero. Besides, the low water-cementitions materials and suitable content of mineral admixture(including fly ash and slag) improve the resistance capacity of chloride penetration, and binding capacity of concrete under hydraulic pressure.

Timing of advanced water flooding in low permeability reservoirs

It is very important to design the optimum starting time of water injection for the development of low permeability reservoirs. In this type of reservoir the starting time of water injection will be affected by a reservoir pressure-sensitive effect. In order to optimize the starting time of water injection in low permeability reservoirs, this effect of pressure change on rock permeability of low permeability reservoirs was, at first, studied by physical simulation. It was shown that the rock permeability decreases exponentially with an increase in formation pressure. Secondly, we conducted a reservoir engineering study, from which we obtained analytic relationships between formation pressure, oil production rate, water production rate and water injection rate. After our physical, theoretical and economical analyses, we proposed an approach which takes the pressure-sensitive effect into consideration and designed the optimum starting time of water injection, based on the principle of material balance. Finally, the corresponding software was developed and applied to one block of the Jiangsu Oilfield. It is shown that water injection, in advance of production, can decrease the adverse impact of the pressure-sensitive effect on low permeability reservoir development. A water-flooding project should be preferably initiated in advance of production for no more than one year and the optimum ratio of formation pressure to initial formation pressure should be maintained at a level between 1.05 and 1.2.

钱家营煤矿瓦斯综合治理技术的研究及应用

钱家营矿业分公司坚持以瓦斯区域性治理为核心,以科学调整矿井开拓布局、优化生产系统,提升瓦斯抽采系统装备能力和瓦斯抽采率为切入点,全面增强通风系统稳定性、安全监测监控可靠性。通过实施通风降阻工程,夯实防突基础,建立防突实验室,全面掌握瓦斯基本参数,建立煤与瓦斯突出预警系统,实现动态监测预警,建立煤与瓦斯突出报警系统,健全完善监测监控系统,确保矿井达到本质安全,提升矿井安全保障和抗灾变能力,实现矿井安全高效生产。

ELASTOPLASTIC ANALYSIS OF THICK-WALLCYLINDER CONSIDERING THE MATERIAL'S DILATANCY CHARACTER

Impermeable bentonite or its mixtures have been proposed as candidate materials to be used in the geotechnical disposal of radioactive nuclear waste. These materials are filled in the space between a canister containing radioactive nuclear waste and an underground chamber to absorb the radionuclide emitting from the canister and simultaneously retard its migration accompanying the perrneation of underground water to prevent the surrounding environment from po1lution. On the basis of the established elastoplastic strain-hardening mechanical model considering the material’s dilatancy character,the authors carry out the stress-strain analysis of a thick-wa1l cylinder in a plane strain state subJected to a pressure difference between internal and external pressures. The analysis may be expected to be a theoretical basis for developing a coupled shear and permeability test apparatus for conducting a permeability test along a sheared plane in a specimen. The apparatus will be used to study the effects of shear strain on the variation of geotechnical materials’ permeability coefficient in order to evaluate the influence of shear strain caused by nonuniform deformation and/or earthquake on the long-term safety of the disposal system of radioactive nuclear waste. The theoretlcal analysls methods in this paper can be directly spread to the analysis of the deformation and stability of tunnels or roadways driven in soft soils or high moisture-bearing soft rocks.

Stability Analysing of Unsaturated Soil Slope

The stability of unsaturated soil slope has been the hot point recently. Especially, the seeping rainfall makes losing stability of unsaturated soil slope, and causes enormous loss to the producation and safety of other people. The seeping rainfall makes volumetric water content of unsaturated soil slope changing, and the volumetric water content has directly relationship with matric suction. And matric suction also has directly relationship with the stability of unsaturated soil slope. So the change of matric suction influence the stability changing, that is, safety coefficient has decided relationship with volumetric water content. The profile of dangerous volumetric water content curves of unsaturated soil slope has been obtained. If a volumetric water content curve of some unsaturated soil slope belongs to one of these dongerous curves, the unsaturated soil slope could be in danger. So this is called DVWCCP(dangerous volumetric water content curves profile). By monitoring the volumetric water content curves can obtain the stability information of some soil slope to serve producing and safety.

Characteristics of the Water Steam Turbocompressors Applied in the Concentrator Systems

The main geometrical and operating parameters of the water steam centrifugal compressors working in various concentrator operating conditions are realized in this paper. The interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well the influence of the concentrator system capacity on the dimensions of the centrifugal compressor are determined to obtain the range of reasonable usage of the centrifugal thermocompression systems in the industrial concentrators. The high peripheral impeller speed, high Mach number and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the water steam centrifugal compressor flow field. The calculating methods for 3-D viscid unsteady transonic fluid flows in the turbocompressors are discussed and the results of CFD simulations and experimental investigations are used for optimal design of the water steam centrifugal compressor flow field. The application of the centrifugal compressor in the industrial concentrators with thermocompression systems and the influence on the energy efficiency of the systems are analyzed. Significant increment of the energy efficiency of the industrial concentrators can be achieved by introduction of the thermocompression systems.

Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe(Yellow) River delta

Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe(Yellow) River delta were investigated experimentally and numerically. Laboratory experiments were carried out to explore the response of a layered silty seabed with various saturation conditions under cyclic wave loads,in which the pore pressure and seepage-related phenomena were particularly monitored. Numerical models to simulate wave-induced seepage in the seabed were presented and evaluated,then applied to the Huanghe River delta. The experimental results show that the excess pore pressure decreases more rapidly at the surface layer,while the seepage-related phenomena are more pronounced when large cyclic loads are applied and the underlying layer is less saturated. The proposed numerical models were verified by comparing with the experiments. The calculated seepage depth agreed well with the depth of the pockmarks in the Huanghe River delta. The experimental and numerical results and the existing insitu investigations indicate that the wave-induced seepage may be a direct cause of the pockmarks in the Huanghe River delta. Extreme storm waves and the dual-layered structure of hard surface layer and weak underlying layer are essential external and internal factors,respectively. Wave- or current-induced scour and transport are possible contributors to the reformation of pockmarks at a later stage.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

An Osmotic Pressure Equation of Uncharged Micelle and Oil/Water Microemulsion Systems

1 INTRODUCTIONMicroemulsion and micelle systems are wide-spread in the industry and agriculture applications,e.g.the petroleum exploitation,food industry chemical engineering and biological engineering,but so far,their properties are still not very well understood.Both micelle and microemulsion systems are dispersed systems and consist of the aggregationsof the surfactant.The difference between them is that there is dispered liquid phase in the coreof the aggregation in the case of the microemulsion,but in the micelle there is not any

Pulsating hydraulic fracturing technology in low permeability coal seams

Based on the difficult situation of gas drainage in a single coal bed of high gas content and low perme- ability, we investigate the technology of pulsating hydraulic pressure relief, the process of crank plunger movement and the mechanism of pulsating pressure formation using theoretical research, mathematical modeling and field testing. We analyze the effect of pulsating pressure on the formation and growth of fractures in coal by using the pulsating hydraulic theory in hydraulics. The research results show that the amplitude of fluctuating pressure tends to increase in the case where the exit is blocked, caused by pulsating pressure reflection and frictional resistance superposition, and it contributes to the growth of fractures in coal. The crack initiation pressure of pulsating hydraulic fracturing is 8 MPa, which is half than that of normal hydraulic fracturing; the pulsating hydraulic fracturing influence radius reaches 8 m. The total amount of gas extraction is increased by 3.6 times, and reaches 50 LJmin at the highest point. The extraction flow increases greatly, and is 4 times larger than that of drilling without fracturing and 1.2 times larger than that of normal hydraulic fracturing. The technology provides a technical measure for gas drainage of high gas content and low permeability in the single coal bed.