Gas Permeability Coefficients Research Articles

An Apparatus to Measure Gas Diffusion and Gas Permeability of Unsaturated Cap Barriers Subjected to Distortion

Abstract Landfill cap barriers are commonly designed to limit infiltration into the landfill, sustain deformation, and prevent the migration of landfill gases to the atmosphere. The gas flow through the unsaturated cap barrier could be due to advection, diffusion, or both based on the degree of saturation of the cap barriers. In the present study, a custom-designed test setup is developed to measure the gas permeability and diffusion coefficient of unsaturated cap barriers sequentially under various settlement rate and distortion levels. The apparatus comprises cylindrical lower and upper chambers, perforated overlapping triangular plates, worm gear, screw jack, motor, controller, and sensors. The lower chamber equipped with an oxygen sensor will be used to measure the variation in the oxygen concentration inside the chamber, leading to the measurement of gas diffusion of cap barriers. The measured quantity of nitrogen gas stored in the gas reservoir is allowed to flow through the cap barrier, leading to the measurement of gas permeability by advection. The gas permeability and gas diffusion at various distortion levels can be determined with the help of perforated overlapping triangular plates and a calibrated screw jack-motor system. The usage of this test setup in assessing the gas flow characteristics of the unsaturated cap barrier under the chosen distortion level is briefly illustrated using two types of cap barriers (compacted clay liner and geosynthetic clay liner) at different moisture contents.

Get 210-2019: State Primary Standard of Units of Specific Adsorption of Gases, Specific Surface Area of Pores, Specific Volume of Pores, Dimension of Pores, Open Porosity, and Coefficient of Gas Permeability of Solid Substances and Fabricated Materials

Methods and means of measurement of the characteristics of the porosity and permeability of solid substances and fabricated materials that are incorporated into GET 210-2019, the State Primary Standard of the units of specific adsorption of gases, specific surface area, specific volume, and dimension of pores, open porosity, and coefficient of gas permeability of solid substances and fabricated materials, are described. A comparison between the metrological characteristics of GET 210-2014 and GET 210-2019 is carried out. The basic means of transmission of the units of quantities that characterize the porosity and permeability of solid substances, such as calibration specimens of approved types based on the micro, meso-, and macroporosity of solid substances, are considered. The results of international comparisons are presented, measurement and calibration capacities are confirmed, and a comparison of the metrological characteristics of GET 210-2019 with the standards of other countries is performed.

A permeability evolution model of coal particle from the perspective of adsorption deformation

AbstractAs an important indicator, permeability can predict the gas drainage yield and prevent the mine gas disasters. We first reviewed our previous inversion method to investigate permeability coefficient of gas in coal particles; however, the relationship between permeability and adsorption pressure had not been summarized and explained theoretically. Here, a permeability evolution model including two crucial parameters of initial permeability and deformation coefficient was developed. The inversion gas permeability coefficients were converted into permeability, and then, the permeability of the same coal sample was fitted according to the evolution model. The results show that (i) the modeled results are matched reasonably well with the inversion permeability data, and thus, this model has been validated; and (ii) as volatile matter content increases, the initial permeability decreases exponentially, but the deformation coefficient basically grows in a linear trend. These two parameters are coupling to lead to a negative exponential decrease in permeability as gas pressure rises.

Mixed Matrix Membranes Based on Fluoropolymers with m- and p-Terphenyl Fragments for Gas Separation Applications.

Novel mixed matrix membranes (MMMs) based on fluoropolymers with m- and p-terphenyl fragments and NaX zeolites were prepared. The fluoropolymers were synthesized by a one-pot, room-temperature, metal-free superacid-catalyzed stoichiometric and nonstoichiometric step polymerization of 2,2,2-trifluoroacetophenone with two multiring aromatic nonactivated hydrocarbons (p-terphenyl and m-terphenyl). MMMs were characterized by scanning electron microscopy (SEM) and infrared (Fourier transform infrared (FTIR)) spectroscopy and used in gas permeability tests. SEM analysis showed interfacial voids in MMMs prepared in N-methyl-2-pyrrolidone (NMP), The interfacial adhesion in the polymer–zeolite system was considerably improved when chloroform was used as a solvent. Permeability coefficients for pristine polymer membranes were 1.3-fold higher in CHCl3 than in NMP for p-terphenyl fragment and 2.0 times higher in NMP than in CHCl3 for the polymer with m-terphenyl fragment. The incorporation of NaX zeolites in the polymeric matrices improved the gas permeability coefficients compared to the pristine membranes. The effects of polymer architecture, casting solvent, and interaction between the organic matrix and the inorganic particles on the gas separation performance of the developed MMMs were investigated.

Analysis of Rotary Vibration of Rigid Friction Pipe Pile in Unsaturated Soil

Based on the mixture theory and previous work, the governing equation of the rotary vibration of rigid friction pipe pile in unsaturated soil is established. The analytical solution of this equation can be used to analyze the displacements and the complex stiffness of rotary vibration. The results show that the contribution to stiffness is as follows: solid < liquid < gas; and the contribution to rotational impedance is as follows: solid > liquid > gas. In addition, when the fluid permeability coefficient decreases, the stiffness decreases and the rotational impedance increases, but the influence is not obvious (especially the gas permeability coefficient). Four different kinds of degradation problems are also presented. Relevant conclusions can provide reference for engineering application.

Investigation of the microporous organization of 1,2-disubstituted polyacetylenes using low-temperature argon sorption and small-angle X-ray scattering

The extra free volume of glassy, highly permeable 1,2-disubstituted polyacetylenes is associated with the microporous organization of these polymers. In this work, the microporosity of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) is investigated by two independent methods—convenient low-temperature Ar sorption and less commonly used small-angle X-ray scattering (SAXS). The Ar sorption data were analyzed in connection with the specific surface area, pore volume, and micropore size distribution. It is shown that the higher specific surface area, total pore volume, and micropore volume of PTMSP than those of PMP are associated with higher gas permeability coefficients. It was found that the Brunauer–Emmett–Teller-specific surface values obtained for PTMSP and PMP from argon sorption isotherms correlate with the specific surface values obtained from the SAXS method. The correlation of the specific surface values obtained from fundamentally different methods makes it possible to evaluate the small-angle scattering method as adequate for assessing the microporosity of polymeric materials. The microporosity of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) is investigated by two independent methods—convenient low-temperature Ar sorption and less commonly used small-angle X-ray scattering (SAXS). The Brunauer–Emmett–Teller-specific surface values obtained for PTMSP and PMP from Ar sorption isotherms correlate with the specific surface values obtained from the SAXS method. The correlation of the specific surface values obtained from fundamentally different methods makes it possible to evaluate the small-angle scattering method as adequate for assessing the microporosity of polymeric materials.

Experimental investigation on methane advection and diffusion in geosynthetic clay liners

Geosynthetic clay liners (GCLs) are widely used in landfill and heap-leach facility cover system for mitigating rainfall infiltration and gas migration into atmosphere. Laboratory tests were conducted to investigate methane diffusion and advection through GCLs. Gas permeability coefficient of GCL for the case with moisture content = 47.5% is one and two orders of magnitude greater than the cases with moisture content = 68.5% and 80.9%, respectively, when 20 kPa vertical stress was applied. The batch adsorption tests indicated that adsorption of methane onto bentonite is negligible. The concentration variation for the adsorption of methane onto bentonite can be neglected. However, methane concentration decreased by 14.2% for the test of methane adsorption onto GCL during the first 2–3 days. This is because methane was adsorbed by the geotextiles rather than by the bentonite in GCL. The large porosity and surface area of geotextiles provide lots of micropores for methane adsorption. Analytical model was then developed to analyze the performance of GCL-based liners system with respect to methane transport. The results indicate that methane emission fluxes for the case with SL + GCL are 7.8 and 5.1 times less than the cases with SL + CCL when the moisture contents were 25.9% and 35.1%, respectively. The methane emission fluxes for both of the SL + GCL and SL + CCL can be neglected when they are fully saturated. GCL is recommended to be used in arid and semi-arid regions rather than CCL. GCL is recommended to be used in arid and semi-arid areas rather than CCL. Advection plays a more important role in methane migration through SL + GCL and SL + CCL than that of diffusion. With moisture contents = 25.9% and 32%, methane emission flux attributed to advection accounts for more than 90% of the total emission flux for both cases of SL + GCL and SL + CCL. With the increase of moisture content of SL, the effectiveness of SL in reducing methane emission increases. The saved space for using GCL + SL composite cover compared with using a single SL cover is 0.7 m when the moisture content equals 25.9%, which is 0.5 m greater than the case when moisture content equals 32%. GMB plays a dominant role in inhibiting methane migration and reducing methane emission flux. When moisture content equals 25.9%, the methane emission fluxes for SL + GMB + GCL and SL + GMB + CCL are 343 times and 2643 times less than the cases with SL + GCL and SL + CCL, respectively.

Effect of porous organic polymers in gas separation properties of polycarbonate based mixed matrix membranes

Polycarbonate (PC) based mixed matrix membranes (MMMs) loaded with porous organic polymers as fillers exhibit very good performance in gas separation of industrial interest. Resulting MMMs show excellent compatibility between the two phases.The MMMs were prepared in less time than the reported PC-based MMMs, by controlled addition of the filler under ultrasound stirring and magnetic stirring sequences. PC-based MMM loaded with 20% of un-functionalized and functionalized filler containing NO2 groups (PC@2Ph and PC@2PhNO2) showed very good performance because all gas permeability coefficients increased while the selectivity remained unchanged for most gas pair and even increased significantly respect to pure PC membrane. MMM prepared with the methylamino-functionalized filler (PC@2PhCH2NH2) showed a greater H2/CH4 and CO2/CH4 separation selectivity in comparison with PC, with a slight decrease in permeability coefficients. Compared with the PC-based MMM previously reported, PC@2Ph and PC@2PhNO2 were competitive for O2/N2 and CO2/CH4 and the best for H2/CH4 separation. The PC@KAPs membranes prepared in this work also improved the performance of PC to hydrogen and methane recovery, become in an attractive for petrochemical industry.

Effect of the CO2-philic ionic liquid [BMIM][Tf2N] on the single and mixed gas transport in PolyActive™ membranes

This study reports on the gas transport properties of four different grades of PolyActive™ polyether-co-polyester multi-block copolymer membranes containing different concentrations (4.8, 9.1, 16.7, 23.1 and 28.6 wt%) of the low-viscous CO2-philic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]). Single gas permeability, solubility and diffusion coefficients of He, H2, N2, O2, CH4 and CO2 were determined at 1 bar and 25 °C in a constant-volume time lag setup. Mixed gas permeability measurements of CO2/CH4 and CO2/N2 mixtures containing 35 and 15 vol% CO2, respectively, were carried out at 25 °C in the pressure range from 1 to 6 bar(a). The transport properties were correlated with the ionic liquid content of the samples, the specific PolyActive™ grade (i.e. chain length, copolymer composition), and previously determined microstructure, crystallinity, thermal and mechanical properties. For all PolyActive™ grades, the single gas permeability decreased in the order CO2 ≫ H2 > He > O2 ≈ CH4 > N2 and it typically increased with increasing IL content, whereas the ideal selectivity decreased with IL content for most gas pairs. None of the membranes revealed significant dependence on the feed pressure in both single and mixed gas permeation tests. Such behavior is typical for predominantly rubber-like materials. Samples based on PolyActive™ 4000PEOT77PBT23 had the strongest dependence on the IL concentration due to its higher weight fraction and higher crystallinity of the polyether phase.The specific behavior of the four polymers was illustrated via their different trends with increasing IL concentration in the Robeson diagrams. The study demonstrates how blending with ionic liquid can be used to tailor the permeability and selectivity of the membranes. It provides insight into the influence of ionic liquid and the weight percentages of the PEO blocks and the PBT blocks in the copolymers on the individual contributions of the solubility and diffusion coefficients on the permeability.

Highly Permeable Polyheteroarylenes for Membrane Gas Separation: Recent Trends in Chemical Structure Design

Progress in membrane gas separation is impossible without the synthesis of new polymers with improved gas-transport and gas-separation characteristics. The most promising polymeric membrane materials with the advantageous combination of permeability and selectivity, which form the 2008 and 2015 Robeson “upper bounds,” are polyheteroarylenes, among which are ladder polybenzodioxanes, polymers of intrinsic microporosity (PIM), polyimides, polyamides, and polyisathines. Their specific feature is the presence of moieties in the chemical structure that in any way contribute to the loosened packing of polymer chains and the increase in gas-permeability coefficients. Among such macromolecular design elements are groups with main chain kinks or bulky substituents increasing the rotation barriers and rigidity of macrochains. A high gas permeability of the polyheteroarylenes under consideration is commonly combined with an increased selectivity for many gas pairs (e.g., O2/N2, CO2/CH4) primarily associated with a high diffusion selectivity, which suggests their chain packing order and makes it possible to call them polymeric molecular sieves.

Characterization and gas transport properties of UV-irradiated polydimethylsiloxane (PDMS)-containing polyimide copolymer membranes

The influence of UV irradiation on gas permeation properties of random segmented poly (imide-siloxane) (PIS) copolymer films was investigated. Random segmented copolymers were synthesized via ester-acid imidization from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) in a 7:3 M ratio with 2,4-diamino mesitylene (DAM) and varying amounts of a diamine terminated polydimethylsiloxane (PDMS) oligomer (Mn = 3000 g/mol). Solvent cast films of these copolymers were UV-irradiated on both sides in air at 365 nm, which induced crosslinking and photooxidation. Pure-gas permeabilities of H2, O2, N2, CH4, and CO2 were measured with upstream pressures ranging from 2 to 18 atm at 35 °C. Gas permeability coefficients of a series of PIS copolymers decreased, and selectivity of all gas pairs increased after UV irradiation due to a decrease in free volume by UV crosslinking and photooxidation.

Liquid CO2 phase transition fracturing technology and its application in enhancing gas drainage of coal mines

Liquid CO2 phase transition fracturing (LCO2-PTF) is an effective and economical technology used to improve the permeability of rock and coal. In this study, the working mechanisms of LCO2-PTF were analysed and relevant equipment was designed to develop and promote the application of this technology. It utilized phase transition equipment (PTE) consisting of a liquid gas container, control unit for the current and gas volume, heating tube, and other components. LCO2 blasting experiments were conducted in an airtight container to investigate the released energy, pressure, and other technical parameters. The application of LCO2-PTF for enhancing gas drainage in coal mines was then evaluated. The results of a blasting experiment showed a maximum energy of 947.12 kJ and revealed that the releasing pressure could be easily changed by varying the plate and heat tube. The releasing pressure remained unchanged within an initial distance and then decreased exponentially. The blasting products were gaseous CO2 and water vapor, with no sparks or flames. The surface temperature of the PTE ranged from 269.32 to 277.96 K. Application of LCO2-PTF in coal mines with low permeability showed gas drainage 3.38 times higher than that achieved with conventional technologies, with methane concentration increasing from 55 to 89%. The attenuation coefficient of gas emissions dropped by 94% and the gas permeability coefficient of the coal body increased more than 23 times after fracturing. The shockwave of the high-pressure gas promoted the development and extension of cracks. The influence radius of the pre-cracking coal seam was 8.1 m, which is 6.75 times that of the original coal seam. The experimental results and the engineering applications indicate that LCO2-PTF is a safe and effective technology to enhance gas drainage in coal mines.

Features of measuring absolute permeability of rocks

Aspects of gas permeability measurement on samples of terrigenic and carbonate rocks of oil and gas collectors, as well as artificial samples on the domestic Darsimeter plant are considered. The following types of reservoir rocks were used for the study: pore, fractured, cavernous. The scope of application of the Darcy Law for pore-type rocks was clarified, which is limited to small pore pressures. Permeability coefficients were determined taking into account the gas slip-law effect of Klinkenberg on regression equations. Apparent permeability at low pressure drops was determined. For a number of samples with low permeability, the pore size was calculated to relate to the apparent permeability value. The calculation was carried out on the basis of the obtained values of structural coefficients of rocks by the method of electrical resistivity and on the basis of porosity values determined using the Preobrazhenskiy method.For a number of crack and capillary samples, the relationship between the pressure gradient and the filtration rate became nonlinear, and types of filtration laws were determined. Establishing the applicability of Darcy 's law or nonlinear law was controlled by constructing indicator curves and calculating the Reynolds number. For terrigenic rocks of high permeability, errors of measurement of gas permeability coefficients at different pressure drop intervals were determined: dispersion and coefficient of variation showing low values were calculated.

Novel semi-fluorinated poly(ether imide)s with benzyl ether side groups: Synthesis, physicochemical characterization, gas transport properties and simulation

The present work reports the preparation of several new poly(ether imide)s (PEIs) from the benzyl ether substituted, fluorinated diamine monomer, 4,4′-((2′,5′-bis(benzyloxy)-3,3′'-bis(trifluoromethyl)-[1,1′:4,4′'-terphenyl]-4,4′'-diyl)bis(oxy))dianiline (TADBE) with different fluorinated and non-fluorinated aromatic dianhydrides as the materials for membrane-based gas separation applications. The PEIs were readily dissolved in numerous organic solvents and cast into freestanding flexible films with tensile strength up to 159 MPa and elongation at break up to 106%. The films were optically transparent and showed dielectric constant as low as 2.47 at 1 MHz and 30 °C for the polymer derived from 6FDA (PEI-b). The structural elucidation of the polymers was done by 1H NMR and FTIR studies. The weight average molecular weight of the polymers was as high as about 255000 g/mol, and dispersity values were with the range as expected for condensation polymers (2.1–2.8). The thermal stability of PEIs was tested carefully to judge their ability for membrane-based application. The polymers showed 10% weight loss temperature above 440 °C in the air with high Tg values (as high as 252 °C) under nitrogen. Three independent methods were used to estimated the gas permeability coefficients of the PEIs. The structure-property correlations on gas transport properties and chemical structure and different physical properties of these PIEs were established. The best combination of selectivity and gas permeability (P) value is seen for the polymer with 6FDA fragment (PEI-b). The group contribution method predicts the permeability coefficients exceptionally well in all three PEIs and for different gases. Molecular dynamics provides a better insight on free volume, free volume size distribution, and morphology of the PEIs.

Development of the reference material of nanoporous zeolite

The article is devoted to the development of a reference material of the sorption roperties of nanoporous zeolite, which ensures metrological traceability of measurement results to the State primary measurement standard of units for specific gas adsorption, specific surface area, specific pore volume, pore size, open porosity and gas permeability coefficient of solid substances and materials GET 210-2019.The paper presents the results of theoretical and experimental studies on optimizing the conditions of sample preparation (thermal training) of the reference material using the thermogravimetric method and differential scanning calorimetry, coupled with mass spectrometric detection of the evolved gases (TG-DSC–MS analysis). The results of establishing the metrological characteristics of the reference material are described, including standard uncertainty due to the method of determining the certified value, as well as standard uncertainties from heterogeneity and instability. The GSO 10734–2015 reference material of the sorption properties of nanoporous zeolite (Zeolite SO UNIIM) has certified metrological characteristics: specific surface area (500–1200) m2/g; specific pore volume (0.10.5) cm3/g; the predominant pore diameter (0.4–0.9) nm; specific argon adsorption (0.001–20.0) mol/kg.The reference material is designed to calibrate measuring instruments and to control accuracy of results of sorption characteristics of nanoporous materials measurements; it can be used to certify appropriate measurement procedures, to test measuring instruments and reference materials for type approval and other types of metrological control.

Transport properties of surface layers from full‐scale reinforced concrete member

AbstractThe durability performance of concrete structure is intimately related to the mass transport properties for the surface layers of concrete members. However, due to several effects, such as segregation, jamming effect and so on, the quality of the surface layer for reinforced member might be obviously different from their core material and material prepared and cured in the laboratory (labcrete). This study aims at understanding the mass transport properties of surface layers from reinforced concrete member, and clarifying the differences among them and those for accompanied labcrete. Specimens prepared from both a full‐scale reinforced beam and labcrete are subjected to experimental investigations on their gas permeability, capillary sorptivity, chloride diffusivity, and chloride migration coefficients. It is found that, for the same specimen, the gas permeability is approximately linear to capillary sorptivity. While the chloride diffusivity is smaller than the rapid migration coefficient. The durability potential of surface layers for the reinforced beam is inferior to that of the inner core material. While the latter is further obviously worse than that of labcrete. In engineering practice, special attention should be paid to ensure the quality of surface layer. When making quantification or prediction for the durability potential of concrete structure, it is more appropriate to use specimens from surface layers of field concrete members rather than those from labcrete.

Gas-separation and physical properties of ABA triblock copolymers synthesized from polyimide and hydrophilic adamantane derivatives

In this study, ABA triblock copolymers derived from 4,4’-(hexafluoroisopropylidene)-diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine (6FDA-TeMPD; PI) and 3-hydroxy-1-adamantyl methacrylate (HAdMA) or 3,5-dihydroxy-1-adamantyl methacrylate (DHAdMA) have been synthesized via atom transfer radical polymerization to generate mechanically tough and thermally stable gas-separation membranes with composition-tunable transport properties. Due to the inherent thermodynamic incompatibility between the chemically dissimilar blocks, these two series of triblock copolymers appear microphase-separated. While the gas permeability coefficients of these triblock copolymer membranes are consistently lower than that of PI due to the reduced fractional free volume of HAdMA and DHAdMA, the solubility coefficients of the copolymers are higher than that of PI due presumably to specific interactions between the polar hydroxyl group(s) and penetrant gas molecules. These triblock copolymers synthesized from PI and hydrophilic adamantane derivatives constitute a new class of nanostructured polymeric materials possessing excellent thermomechanical properties in conjunction with designer gas-separation properties.

Synthesis and Characterization of Novel Nanoporous Gl-POSS-Branched Polymeric Gas Separation Membranes.

Novel nanoporous Gl-POSS-branched polymers based on the macroinitiator of anionic nature, 2,4-toluene diisocyanate, and octaglycidyl polyhedral oligomeric silsesquioxane (Gl-POSS) were obtained as gas separation membranes. The synthesis of polymers was carried out using various loads of Gl-POSS. It was found that the main reaction proceeding with 2,4-toluene diisocyanate is the polyaddition, accompanied by the isocyanate groups opening of the carbonyl part. This unusual opening of isocyanate groups leads to the formation of coplanar acetal nature polyisocyanates (O-polyisocyanate). The terminal O-polyisocyanate links initiate the subsequent opening of the epoxide rings in Gl-POSS. As a result, Gl-POSS serves as a hard and bulky branching agent and creates the specific framing supramolecular structure, which leads to the formation of nanopores in the polymer, where the flexible polyether components are located inside the cavities. Thermal, mechanical, physical, and chemical properties of the obtained polymers were studied at various Gl-POSS contents in the polymer matrix. It was found that these polymers show high selectivity of gas transport properties for pure ammonia relative to nitrogen and hydrogen at ambient temperature. Measurements showed that the gas permeability coefficients and the values of ideal selectivity were in a non-additive dependence to the Gl-POSS content.

Permeability of Concrete and Correlation with Microstructure Parameters Determined by 1H NMR

Water and gas permeability coefficients of concrete with different water-binder (w/b) ratios and admixtures were measured by a self-designed test device based on the steady-state flow method for liquid and the method of differential pressure in stability for gas, respectively. In addition, the micropore structure of concrete was determined by 1H nuclear magnetic resonance (NMR). Results indicated that there are good correlations between water and gas permeability of concrete with different w/b ratios, with correlation coefficient greater than 0.90. Better correlations between water permeability and segmental contributive porosity ranged from 10 to 100 nm and 100 to 1000 nm can be identified, but the gas permeability is more relevant to the segmental contributive porosity ranging from 100 to 1000 nm. Moreover, the correlation between water permeability and contributive porosity for each pore diameter is always better than that of gas permeability. The influence of admixtures on the relationship between permeability and pore size distribution of concrete is significant. Moreover, water permeability coefficient is one or two orders of magnitude lower than the gas permeability coefficient.

The method to assess the gas flow of a porous bed product derived from underground coal gasification technology

The article describes the technical and process aspects of the technology resulting from the thermal processing of coal in an unconventional way. Selected methods of assessing gas permeability through a porous bed, which is characterized by hydrodynamic gas flow, are indicated.The presented measurement results indicate a clear impact of the type of material on gas permeability and the impact of flow directivity on the value of the gas stream. A new method of hydrodynamic assessment of the permeability coefficient was pointed out, which was correlated with selected criteria characteristic for porous materials derived from coal gasification technology.Based on the process assessment of the research results, it was found that it is useful to use such hydrodynamic features as horizontal, vertical and effective gas permeability coefficient. These values can be used to identify technological quality indicators for raw gas, which is a product of Underground Coal Gasification.The reason for writing this article is the current nature of this topic, which results from the observed reason for the so-called clean coal technologies and the development of modern clean energy technologies that give rise to alternative energy sources, especially renewable energy sources.