AN EXTENSION OF THE METHOD FOR PREDICTING PERMEABILITY THROUGH POLYMER MEMBRANES FROM SIMPLE GASES TO WATER VAPOR

It is found that there is a linear relationship between log P-w, and the parameter term V-f/0.5 E(coh) [1+(delta(w) - delta(p))(2)/delta(p)(2), from the water permeability (P-w) data of 21 polymers covering 4 orders of magnitude. This correlation may be useful in choosing membrane materials for dehumidification of gases.

Temperature Dependency of Water Vapor Permeability of Shape Memory Polyurethane

Solution-cast films of shape memory polyurethane have been investigated.Differential scanning calorimetry, DMA, tensile test, water vapor permeability and the shape memory effect were carried out to characterize these polyurethane membranes. Samples cast at higher temperatures contained more hard segment in the crystalline state than a sample cast at lower temperature. The change in the water vapor permeability (WVP) of SMPU films with respect to the temperature follows an S-shaped curve, and increases abruptly at T m of the soft segment for the fractional free volume (FFV, the ratio of free volume and specific volume in polymers) increased linearly with temperature. The water vapor permeability dependency of the temperature and humidity contribute to the result of the change of diffusion and solubility with the surrounding air condition. The diffusion coefficient (D) are the function of temperature and show good fit the Arrhenius form but show different parameter values when above and below T g. The crystalline state hard-segment is necessary for the good shape memory

Synthesis of Hyperbranched Polymers and Its Effect on Water Vapor Permeability of Microfiber Synthetic Leather

A series of hyperbranched poly(amine-ester)polyols were synthesized by the polycondensation of N,N-diethylol-3-amine-methylpropionate(prepared by Michael addition reaction of methyl acrylate with diethanolamine)as an AB2-type monomer with trimethylol propane as the core moiety,proceeding in one-step procedure in the melt with p-toluenesulfonic acid as catalyst.The obtained monomer and polymers were characterized by FTIR and 1H-NMR spectroscopy.The solubility and surface activity in aqueous solution of the polymers were also examined.The gas permeability,water vapor permeability,and moisture absorption of microfiber synthetic leather treated by hyperbranched polymer were studied.The optimum conditions were that the dosage of dye and hyperbranched polymer was 5% and 10%,respectively.The water vapor permeability and moisture absorption of microfiber synthetic leather reached to 0.525 4 mg/(10 cm2·24 h)and 0.046 7 mg/(10 cm2·24 h).Compared with blank samples,they increased by 15% and 35%,respectively.However,the dosage of hyperbranched polymer has little influence on gas permeability of microfiber synthetic leather.SEM results show that the fiber of microfiber synthetic leather treated by hyperbranched polymer is incompact.

Experimental determination and prediction of the compressibility factor of high CO_2 content natural gas with and without water vapor

In order to study the effect of different CO2 contents on gas compressibility factor（Z-factor）,the JEFRI-PVT apparatus has been used to measure the Z-factor of dry natural gas with CO2 content range from 10.74 to 70.42 mol%at the temperature range from 301.2 to 407.3 K and pressure range from 7 to 44 MPa.The results show that Z-factor decreases with increasing CO2 content in natural gas at constant temperature and increases with increasing temperature for natural gas with the same CO2 content.In addition,the Z-factor of water-saturated natural gas with high CO2 content has been measured.A comparison of the Z-factor between natural gas with and without saturated water vapor indicates that the former shows a higher Z-factor than the latter.Furthermore,Peng-Robinson,Hall-Yarborough,and Soave-Benedict-Webb- Rubin equations of state（EoS）are used for the calculation of Z-factor of high CO2 content natural gas with and without water vapor.The optimal binary interaction parameters（BIP）for PR EoS are presented.The measured Z-factor is compared with the calculated Z-factor based on three models,which shows that PR EoS combined with van der Waals mixing rule for gas without water and Huron-Vidal mixing rule for water-saturated gas,are in good agreement with the experimental data.

Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties(e.g.suction and water retention)of soil.However,variations in densities alter the properties of the soil ebiochar mix.Such density variations are observed in agriculture(loosely compacted)and engineering(densely compacted)applications.The influence of biochar amendment on gas permeability of soil has been barely investigated,especially for soil with different densities.The major objective of this study is to investigate the water retention capacity,and gas permeability of biochar-amended soil(BAS)with different biochar contents under varying degree of compaction(DOC)conditions.In-house produced novel biochar was mixed with the soil at different amendment rates(i.e.biochar contents of 0%,5%and 10%).All BAS samples were compacted at three DOCs(65%,80%and 95%)in polyvinyl chloride(PVC)tubes.Each soil column was subjected to dryingewetting cycles,during which soil suction,water content,and gas permeability were measured.A simplified theoretical framework for estimating the void ratio of BAS was proposed.The experimental results reveal that the addition of biochar significantly decreased gas permeability kg as compared with that of bare soil(BS).However,the addition of 5%biochar is found to be optimum in decreasing kg with an increase of DOC(i.e.k_(g,65%)>k_(g,80%)>k_(g,95%))at a relatively low suction range(<200 kPa)because both biochar and compaction treatment reduce the connected pores.

Permeability evolution and gas flow in wet coal under non-equilibrium state:Considering both water swelling and process-based gas swelling

Accurate knowledge of gas flow within the reservoir and related controlling factors will be important for enhancing the production of coal bed methane.At present,most studies focused on the permeability evolution of dry coal under gas adsorption equilibrium,gas flow and gas diffusion within wet coal under the generally non-equilibrium state are often ignored in the process of gas recovery.In this study,an improved apparent permeability model is proposed which accommodates the water and gas adsorption,stress dependence,water film thickness and gas flow regimes.In the process of modeling,the water adsorption is only affected by water content while the gas adsorption is time and water content dependent;based on poroelastic mechanics,the effective fracture aperture and effective pore radius are derived;and then the variation in water film thickness for different pore types under the effect of water content,stress and adsorption swelling are modeled;the flow regimes are considered based on Beskok’s model.Further,after validation with experimental data,the proposed model was applied to numerical simulations to investigate the evolution of permeability-related factors under the effect of different water contents.The gas flow in wet coal under the non-equilibrium state is explicitly revealed.

Optimized water vapor permeability of sodium alginate films using response surface methodology

The water vapor permeability （WVP） of films is important when developing pharmaceutical applications. Films are frequently used as coatings, and as such directly influence the quality of the medicine. The optimization of processing conditions for sodium alginate films was investigated using response surface methodology. Single-factor tests and Box-Behnken experimental design were employed. WVP was selected as the response variable, and the operating parameters for the single-factor tests were sodium alginate concentration, carboxymethyl cellulose （CMC） concentration and CaClz solution immersion time. The coefficient of determination （R2） was 0.97, indicating statistical significance. A minimal WVP of 0.389 8 g-mm/（m^2.h.kPa） was achieved under the optimum conditions. These were found to be a sodium alginate concentration, CMC concentration and CaCl2 solution immersion time at 8.04%, 0.13%, and 12 min, respectively. This provides a reference for potential applications in manufacturing film-coated hard capsule shells.

Effect of cobalt oxide on performance of Pd catalysts for lean-burn natural gas vehicles in the presence and absence of water vapor

Pd-based catalysts modified by cobalt were prepared by co-impregnation and sequential impregnation methods,and characterized by X-ray powder diffraction （XRD）,N2 adsorption/desorption （Brunauer-Emmet-Teller method）,CO-chemisorption and X-ray photoelectron spectroscopy （XPS）.The activity of Pd catalysts was tested in the simulated exhaust gas from lean-burn natural gas vehicles.The effect of Co on the performance of water poisoning resistance for Pd catalysts was estimated in the simulated exhaust gas with and without the presence of water vapor.It was found that the effect of Co significantly depended on the preparation process.PdCo/La-Al2O3 catalyst prepared by co-impregnation exhibited better water-resistant performance.The results of XPS indicated that both CoAl2O4 and Co3O4 were present in the Pd catalysts modified by Co.For the catalyst prepared by sequential impregnation method,the ratio of CoAl2O4/Co3O4 was higher than that of the catalyst prepared by co-impregnation method.It could be concluded that Co3O4 played an important role in improving water-resistant performance.

The Effect of Plasticizers on Mechanical Properties and Water Vapor Permeability of Gelatin-Based Edible Films Containing Clay Nanoparticles

The effects of glycerol and sorbitol as two plasticizers on mechanical properties, water vapor permeability, thermal properties, color and capability of heat sealing of gelatin films (of phytophagous fish, bovine gelatin with high gel-forming ability, and bovine gelatin with low gel-forming ability) containing clay nanoparticles were studied in this research. For this purpose, 6 × 2 × 3 factorial experiments using the completely randomized design and comparison of the means at 95% confidence level (α = 0.05) were performed. Higher concentrations of plasticizers increased percentage elongation to the breaking point. When glycerol concentration was raised to over 20%, flexibility of the layers improved but their water vapor permeability increased. The minimum passage of water vapor was that of fish-skin gelatin films containing clay nanoparticles and 30% sorbitol, and the maximum that of bovine gelatin films with high gel-forming ability which contained nanoparticles but no plasticizers (p 0.05). All samples had heat sealing capability, and fish-skin gelatin films containing clay nanoparticles had better heat sealing capability compared with the other samples so that fish-skin gelatin films containing clay nanoparticles with 25% glycerol and 5% sorbitol had the highest flexibility and tensile strength, and remained attached to where they were heat sealed. Electron microscope images showed that films without plasticizers had uniform surfaces, but that samples containing glycerol at concentrations of over 0.20 g/g gelatin exhibited cavities between gelatin chains and that water vapor permeability in gelatin films containing clay nanoparticles.

Adaptability of Development Methods for Offshore Gas Cap Edge Water Reservoirs under Different Permeability Levels

The BZ 34-1 oilfield is a typical gas cap edge water reservoir in the Bohai oilfield. The main characteristics of the oilfield were multi-phase sand body stacking and the sand body was composed of three parts: gas cap, oil reservoir, and edge water. The actual production site results show that the permeability difference of multi-layer sand bodies has a serious impact on the development effect. This article establishes a typical reservoir model numerical model based on the total recovery degree of the reservoir and the recovery degree of each layer, and analyzes the impact of permeability gradient. As the permeability gradient increases, the total recovery degree of all four well patterns decreases, and the total recovery degree gradually decreases. The recovery degree of low permeability layers gradually decreases, and the recovery degree of high permeability layers gradually increases. As the permeability gradient increases, the degree of recovery gradually decreases under different water contents. As the permeability gradient increases, the reduction rate of remaining oil saturation in low permeability layers is slower, while the reduction rate of remaining oil saturation in high permeability layers was faster. By analyzing the impact of permeability gradient on the development effect of oil fields, we could further deepen our understanding of gas cap edge water reservoirs and guide the development of this type of oil field.

The primary controlling parameters of porosity, permeability,and seepage capability of tight gas reservoirs:a case study on Upper Paleozoic Formation in the eastern Ordos Basin,Northern China

Tight sandstone gas(hereafter"tight gas")has become a subject of unconventional gas exploration globally.The large-scale development and use of tight gas resources in the USA,in particular,facilitated the rapid rebound of natural gas production in the USA,in addition to driving the rapid development of tight gas worldwide.In the eastern Ordos Basin,the Upper Paleozoic feature includes multiple layers of gas,a shallow depth,and notable potential for exploration and development.However,the reservoirs in the area are relatively tight,exhibit strong heterogeneity,and possess a complex micropore structure,thus restricting the eff ective economic development of oil and gas.Thus,research on the primary parameters controlling pore throat structure and the seepage capability of low-permeability reservoirs will be beneficial for the effcient exploration and development of natural gas in the eastern Ordos Basin.The parameters of reservoir porosity and percolation ability,as well as permeability,were analyzed using systematic sampling of the of the Upper Paleozoic Benxi,Taiyuan,and Shanxi Formations in the eastern Ordos Basin,constant-rate mercury injection experiments,nuclear magnetic resonance analysis,and gas–water-phase experimental studies.The results indicate that reservoir porosity is controlled by the effective pore volume and number,whereas permeability is controlled by the largest throat radius,rather than the average.The effective pore volume controls the movable fluid saturation,while reservoir percolation capability is controlled by the effective pore volume,irreducible water saturation,and size of the gas–water two-phase seepage zone.

Self-sealing of fractures in indurated claystones measured by water and gas flow

Self-sealing of fractures in the indurated Callovo-Oxfordian(COX)and Opalinus(OPA)claystones,which are considered as host rocks for disposal of radioactive waste,was investigated on artificially fractured samples.The samples were extracted from four lithological facies relatively rich in clay mineral,carbonate and quartz,respectively.The self-sealing of fractures was measured by fracture closure,water permeability variation,gas penetration,and recovery of gas-induced pathways.Most of the fractured samples exhibited a dramatic reduction inwater permeability to low levels that is close to that of intact rock,depending on their mineralogical composition,fracture intensity,confining stress,and load duration.The self-sealing capacity of the clay-rich samples is higher than that of the carbonate-rich and sandy ones.Significant effects of sample size and fracture intensity were identified.The sealed fractures become gas-tight for certain in-jection pressures.However,the measured gas breakthrough pressures are still lower than the confining stresses.The gas-induced pathways can recover when contacting water.These important findings imply that fractures in such indurated claystones can effectively recover to hinder water transport but allow gas release under relatively low pressures without compromising the rock integrity.

Deformation and water/gas flow properties of claystone/bentonite mixtures

As a potential engineered barrier material for disposal of radioactive waste in clay formations,claystone aggregate excavated from the Opalinus clay(OPA),its mixture with bentonite MX80 in a mass ratio of 7/3,and pure bentonite were extensively investigated with respect to the hydro-mechanical properties and performances.With these materials,a series of parallel experiments was performed under sequentially applied conditions of hydration with synthetic porewater of the clay formation,consolidation and water flow under increased stresses,and gas injection into the water-saturated and compacted materials under loading.Significant responses of the clay mixtures were observed.Main findings include:(1)the hydration and induced swelling of the mixtures are mainly dominated by bentonite content and dry density;(2)the consolidation decreases the porosity and water permeability exponentially by 2-3 orders of magnitude to low values of 10^(-18)-10^(-20) m^(2) at stresses of 2-5 MPa,depending upon bentonite content;and(3)the gas penetration in the water-saturated and compacted bentonite is characterised by a cyclic pressure rising/dropping process limited in between the upper breakthrough and lower shut-off boundaries,whereas the compacted claystone and claystone/bentonite mixture allow for gas release at low and moderate pressures.The results are helpful for design of the engineered barriers for safe isolation of radioactive waste in repositories.

Influence of water vapor on the separation of volatile organic compound/nitrogen mixture by polydimethylsiloxane membrane

In the industrial treatment of waste volatile organic compound(VOC)streams by membrane technology,a third impurity,generally,water vapor,coexists in the mixture of VOC and nitrogen or air,and can affect membrane performance and the design of the industrial process.This study focused on the investigation of the effect of water vapor on the separation performance of the separation of VOC/water/nitrogen mixtures by a polydimethylsiloxane(PDMS)membrane.Three types of VOCs:water-miscible ethanol,water-semi-miscible butanol,and water-immiscible cyclohexane,were selected for the study.Different operating parameters including,concentration of the feed VOC,feed temperature,and concentration of the feed water were compared for the separation of binary and ternary VOC/nitrogen mixtures.The interaction between the VOC and water was analyzed to explain the transportation mechanism after analyzing the difference in the membrane performance for the separation of binary and ternary mixtures.The results indicated that the interaction between the VOC(or nitrogen)and water is the key factor affecting membrane performance.Water can promote the permeation of hydrophilic VOC but prevent hydrophobic VOC through the membrane for the separation of ternary VOC/water/nitrogen mixtures.These results will provide fundamental insights for the design of the recovery application process for industrial membrane-based VOCs,and also guidance for the investigation of the separation mechanism in vapor permeation.

Induced drill-spray during hydraulic slotting of a coal seam and its influence on gas extraction

Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes the effects of water jet damage during slotting.A simulation of the stresses around the drill hole and slot was prepared using FLAC-3D code.It helps explain the induction of drill spray during hydraulic slotting.The stress concentration around the bore increases as the diameter of the hole increases.As the hole enlarges the variation in stress also increases,which introduces an instability into the coal.This allows easy breaking and removal of the coal.Destruction of the coal structure by the water jet is the major factor causing drill spray.Energy stored as either strain or gas pressure is released by the water jet and this causes the coal to fracture and be expelled from the hole.Field tests showed the effect on gas extraction after slotting with drill spray.The concentration of gas increases after drilling.Compared to conventional techniques,the hydraulic slotted bore gives a gas concentration three times higher and has an effective range twice as far.This makes the gas extraction process more efficient and allows reduced construction effort.

Hydraulic drill hole reaming technology with large flow and draining of coal mine gas

This paper takes Zhaozhuang mine in Shanxi province as an example to study the technology of hydraulic reaming drill hole for improving the gas extraction.The influence of the physical properties of coal seam on the hydraulic reaming drill holes and the draining of coal mine gas were analyzed and discussed for different coal structure areas,and the following conclusions were made.Hydraulic drill hole reaming has had a positive impact in Zhaozhuang Mine,and can improve the efficiency of gas extraction to different degrees.The water jet pressure used in hydraulic drill hole reaming mainly depends on the structure of the coal.When the coal seam basically becomes integrated,the critical water jet pressure increases,the discharge becomes relatively easy to achieve,the blocking effect on the gas extraction decreases,and the gas extraction significantly increases after the reaming process.When the coal seam is broken,the critical water jet pressure decreases,the discharge becomes difficult to achieve,the blocking effect on the gas extraction becomes obvious,and the gas extraction changes slightly after reaming.

Progress on the hydraulic measures for grid slotting and fracking to enhance coal seam permeability

A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.

Pd catalysts supported on modified Zr_(0.5)Al_(0.5)O_(1.75) used for lean-burn natural gas vehicles exhaust purification

Composite supports Zr0.5Al0.5O1.75 modified by metal oxides, such as La2O3, ZnO, Y2O3 or BaO, were prepared by co-precipitation method, and palladium catalysts supported on the modified composite supports were prepared by impregnation method. Their properties were characterized by X-ray diffraction （XRD）, NH3 temperature-programmed desorption （NH3-TPD）, He temperature-programmed reduction （He-TPR）, N2 adsorption/desorption, and CO-chemisorption. The catalytic activity and the resistance to water poisoning of the prepared Pd catalysts were tested in a simulated exhaust gas from lean-burn natural gas vehicles with and without water vapor. The results demonstrated that the modified supports had an apparent effect on the performance of Pd catalysts, compared with the Pd catalyst supported on the unmodified ZrA1. The addition of ZnO or Y203 promoted the conversion of CH4. In the absence of water vapor, Pd/ZnZrA1 exhibited the best activity for CH4 conversion with the light-off temperature （Tso） of 275 ℃ and the complete conversion temperature （T90） of 314 ℃, respectively. However, in the presence of water vapor, Pd/YZrA1 was the best one over which the light-off temperature （Tso） of methane was 339 ℃ and the complete conversion temperature （T90） was 371 ℃. These results indicated that Pd catalyst supported on the modified composite ZrA1 support showed excellent catalytic activity at low temperature and high resistance to H20 poisoning for the exhaust purification of lean-burn natural gas vehicles.

A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system

A micro-nano pore three-dimensional visualized real-time physical simulation of natural gas charging, in-situ pore-scale computation, pore network modelling, and apparent permeability evaluation theory were used to investigate laws of gas and water flow and their distribution, and controlling factors during the gas charging process in low-permeability(tight) sandstone reservoir. By describing features of gas-water flow and distribution and their variations in the micro-nano pore system, it is found that the gas charging in the low permeability(tight) sandstone can be divided into two stages, expansion stage and stable stage. In the expansion stage, the gas flows continuously first into large-sized pores then small-sized pores, and first into centers of the pores then edges of pores;pore-throats greater than 20 μm in radius make up the major pathway for gas charging. With the increase of charging pressure, movable water in the edges of large-sized pores and in the centers of small pores is displaced out successively. Pore-throats of 20-50 μm in radius and pore-throats less than 20 μm in radius dominate the expansion of gas charging channels at different stages of charging in turn, leading to reductions in pore-throat radius, throat length and coordination number of the pathway, which is the main increase stage of gas permeability and gas saturation. Among which, pore-throats 30-50 μm in radius control the increase pattern of gas saturation. In the stable stage, gas charging pathways have expanded to the maximum, so the pathways keep stable in pore-throat radius, throat length, and coordination number, and irreducible water remains in the pore system, the gas phase is in concentrated clusters, while the water phase is in the form of dispersed thin film, and the gas saturation and gas permeability tend stable. Connected pore-throats less than 20 μm in radius control the expansion limit of the charging pathways, the formation of stable gas-water distribution, and the maximum gas saturation. The heterogeneity of connected pore-throats affects the dynamic variations of gas phase charging and gas-water distribution. It can be concluded that the pore-throat configuration and heterogeneity of the micro-nanometer pore system control the dynamic variations of the low-permeability(tight) sandstone gas charging process and gas-water distribution features.

Low Density Wood Impregnation with Water-Repellent Organosilicic Compounds

Many protective treatments for low density wood are applied by impregnation to give waterrepellency and to control pathologies that usually have this substrate. The properties of Araucaria angustifolia, chemically modified by impregnation with methyltriethoxysilane, n-octyltriethoxysilane and mixtures of both in several ratios, were investigated to achieve mainly high dimensional stability, low capillary water absorption as well as satisfactory water vapor permeability. The aforementioned impregnants produce the wood chemical modification, involving the reaction of hydroxyl groups of the wood with the hydrolysis products of alcoxysilanes. It is concluded that the organosilicon polymers allow improving important characteristics of wood: 1) the non-occlusive coating keeps the water vapor permeability unaltered;2) the alkoxysilane type defines the hydrophobicity and the continuity of coating formed on the pore wall and finally;3) the polymeric structure formed after finishing solgel process incises both on the capillary water absorption and the dimensional stability. In addition, the studied treatments have the advantage of allowing that the water vapor, which permeates through the orga-nosilicon coating placed on cell wall, can exit by hydrophobic repulsion and thus, prevent faults appearance generated by the condensed water inside of wood.