Pore Characteristics Of Coal Research Articles

Exploration of Changes in Coal Pore Characteristics and Gas Adsorption Characteristics Based on Influence of Stress

As the mining depth increases, the effect of stress on the gas adsorption of coal gradually becomes significant. There are significant differences in the pore volume, specific surface area, and adsorption characteristics of coal before and after stress. In this study, the porosity variation characteristics of coal were studied using axial and confining pressure loading processes, and volumetric stress was introduced to characterize the pore variation law of coal under triaxial stress. By calculating the stress values at different burial depths, gas isothermal adsorption experiments were conducted on coal under different stress effects. The Langmuir equation, D-A equation, and Freundlich empirical formula were used to fit the adsorption experimental results. Combining experiments and models to predict the adsorbed and free gas content under stress, we described the gas adsorption law of coal under different stress effects.

A novel numerical reconstruction method of coal based on characteristics of the cleat system

To effectively characterize the characteristics of the pore network of coal and to provide a realistic flow channel for flow simulation, a numerical reconstruction method of coal based on characteristics of the cleat system was proposed. Based on the real coal obtained through high-resolution micrometer CT, the cleat system characteristic parameters are defined and extracted. Then, a series of coals with different pore characteristics at the same scale and the same pore characteristics at different scales were reconstructed. Besides, the applicability of box dimension in calibrating the pore characteristics of coals was quantitatively analyzed. The results show that the coals reconstructed based on the method proposed in this paper can truly restore the pore characteristics of the real coal, especially the non-extension features of cleats; When the cleat system characteristic parameters remain consistent, the reconstructed coals maintain the same pore characteristics, with an average error of 3.37 % in the autocorrelation function, 0.78 % in the variation function and 1.94 % in the average percolation probability function. The box dimension can effectively identify the differences in pore characteristics of coals. At the same scale, as the distance between face cleats increases, the value of the box dimension of the reconstructed coals monotonically decreases, with a fitting slope of −0.22; At different scales, when the cleat system characteristic parameters remain the same, the value of the box dimension of the reconstructed coals is consistent, with an average relative error of 0.34 %. The research results provide a reasonable and effective flow channel for the microscopic/mesoscopic flow simulation of coalbed methane and provide a reference for the quantitative calibration of the pore characteristics of coals.

Construction of a microscopic molecular model of Hongqingliang long-flame coal for potential application in adsorption simulation

The present study aims to develop a tailored microscopic molecular model for analyzing the adsorption properties of Hongqingliang (HQL) coal. The chemical structure of the coal was thoroughly analyzed through the utilization of various techniques, including elemental analysis, Carbon-13 Nuclear Magnetic Resonance spectroscopy (13C NMR), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FTIR). Subsequently, a three-dimensional periodic microscopic molecular model for HQL coal was constructed, followed by the development of a 4 nm fracture pore model. To validate the modeling approach, a comprehensive comparative analysis was conducted utilizing nitrogen adsorption isotherms at 77.35 K. The results indicate that the amorphous cell model constructed in Material Studio solely comprises micropores narrower than 1 nm, making it unsuitable for simulating coal's pore characteristics. Conversely, the nitrogen adsorption isotherm of the 4 nm fracture pore model matches actual results. Therefore, to analyze the pore adsorption characteristics of coal, it is necessary to utilize the amorphous cell model to construct a characteristic pore model for coal.

Effect of the pore structure characteristics of coal samples on the dynamic adsorption of water vapor

In order to study the dynamic adsorption process of water vapor in the pore structure of different coal samples (YJL for lignite, SEK for bituminous coal and BJ for anthracite). The pore structure characteristics of the three coal samples were analyzed by mercuric pressure method, liquid nitrogen adsorption method and infrared spectroscopy. Further, the water vapor adsorption capacity of the three coal samples under different humidity conditions was determined by dynamic water vapor sorption (DVS) experiments. In addition, the monolayer adsorption and multilayer adsorption at different humidity were calculated using the Dent model. The results showed that YJL had the largest surface pore volume and oxygen functional group parameter (IO = 12.41), and its water vapor adsorption capacity was also the highest. However, under high humidity conditions, the presence of a large number of pore throats in the YJL coal samples hindered multilayer adsorption, resulting in a water vapor adsorption percentage of only 18.07 %. On the other hand, SEK has a small oxygen functional group parameter (IO = 5.81), poor pore connectivity, and a certain pore throat structure, resulting in a low water vapor adsorption capacity of SEK coal samples, with a water vapor adsorption proportion of only 23.76 %. BJ coal has a large pore volume and a large number of oxygen functional groups on the surface (IO = 8.84), which has a good pore connectivity and the least number of pore throats structure, resulting in a water vapor adsorption ratio is higher at 87.38 %. On this basis, cylindrical and wedge-shaped pore models of coal samples were constructed, and molecular dynamics simulations were carried out to investigate the adsorption characteristics of water vapor in these pore models. The results show that the adsorption process of water molecules in coal develops continuously with “initial-water chain-water bridge-water lock”. By summarizing and analyzing the above experimental results, four control mechanisms of coal pore characteristics affecting water vapor adsorption were clarified. These findings are of great significance for studying the movement of water vapor in coal seams and understanding the degree of water confinement caused by hydraulic control measures.

Periodic action mechanism of soaking on the evolution of lignite pore structure and microactive groups

As the mining of the overlying coal seam advances, the risk of spontaneous combustion (SC) of water-immersed and air-dried coal in the overlying goaf increases. The structure of functional groups in coal is the fundamental factor for the occurrence of oxidation and heat production, and the surface pores are the main sites of oxidation reactions. In order to explore the mechanism of action of water immersion on the macrostructure and micro-group of lignite, the water-immersed coals (WIC) of 30 days (I30), 60 days (I60), 90 days (I90), 120 days (I120) and 150 days (I150) were prepared. The surface pore characteristics of coal and the evolution of active functional group structure were studied by nitrogen adsorption and infrared spectroscopy. The adsorption capacity of pores and surface structure of coal were quantitatively characterized by pore adsorption kinetic equations and fractal methods. The results showed that the fine-necked bottle-shaped pore structure of water-immersed lignite decreased, and the wedge-shaped pores and parallel plate slits increased. After water-soaking, the specific surface area of lignite increased first and then decreased, the pore volume and pore diameter increased gradually, D1 decreased gradually, D2 increased gradually, and the pore adsorption potential increased gradually, which characterized the gradual pore structure complexity and enhanced adsorption capacity. Water-soaking triggered the conversion of active carbon-hydrogen bonds at the α-position of lignite molecules into active carbon–oxygen single bonds with alcohol-oxygen bonds. I90 and I120 have the highest content of active functional groups, indicating that the oxidation activity of lignite immersed in water for 90–120 days is the highest. This study provides a new method for the quantitative characterization of coal adsorption and has reference value for the study of SC mechanism of water-immersed, air-dried coal in the overlying goaf of close distance coal seam.

Effect of supercritical CO2 extraction on pore characteristics of coal and its mechanism

Abundant pore space in coal is not only the place for the accumulation of coalbed methane (CBM), but also the tunnel for gas migration. In this study, five sets of coal samples before and after the second coalification were selected from the eastern margin of Ordos Basin to simulate supercritical CO2 (Sc-CO2) extraction in supercritical extraction equipment. The evolutions of pore structure and porosity were tested by mercury intrusion porosimetry and nuclear magnetic resonance spectroscopy to compare the changes of pore structure and porosity due to the Sc-CO2 extraction, and to explain the related mechanism. The results show that: (1) Pore volume, pore specific surface area, and connectivity characteristics changed significantly due to Sc-CO2 extraction, and the increment of pore volume and pore specific surface area presented a law of increase–decrease–increase with the increase in the coal rank, and the turning point was near the second coalification. (2) The porosity increment change trend due to Sc-CO2 extraction was increase–decrease–increase with increasing coal rank, and the turning point was again near the second coalification, which supports the mercury intrusion porosimetry results. (3) The changes were observed in the porosity characteristics due to Sc-CO2 extraction through pore-increasing and expanding effects. Before the second coalification, the pore-increasing and expanding effects co-existed in the micropores, and after the second coalification, the pore-expanding effect mainly existed in the transitional pores and above. (4) The variation model for the pore structure of coal due to Sc-CO2 extraction was established. The conclusions offer not only important theoretical significance for the CO2-enhanced CBM (CO2-ECBM) mechanism but also important significance for CO2-ECBM engineering.

Coal Facies and Its Effects on Pore Characteristics of the Late Permian Longtan Coal, Western Guizhou, China

The coal facies and their effects on the coal pore characteristics of the Late Permian Longtan Formation, western Guizhou, were studied, using diverse experiments of macerals and minerals compositions, vitrinite reflectance, and pore characteristics. The results show that five coal facies exist in studied samples, and they are shallow-water covered forest peat swamp facies, moist forest peat swamp facies, dry forest peat swamp facies, low peat swamp facies, and wet land herbaceous peat swamp facies. Among them, the moist forest peat swamp facies accounts for the largest proportion, followed by the shallow-water covered forest peat swamp and dry forest peat swamp facies. The order of pore development degree is identical with the order of moist forest peat swamp facies coal > shallow-water covered forest peat swamp facies coal > dry forest peat swamp facies coal. In contrast to shallow-water covered forest peat swamp facies and dry forest peat swamp facies samples, moist forest peat swamp facies samples have higher porosity and larger pore size. Coal facies play an important role in controlling the pore structure of coal reservoir, which have more effect on pore size distribution than coal rank for the samples in this study.

A Study on the Pore Structure and Fractal Characteristics of Briquettes with Different Compression Loads

In order to study the effects of different compression loads on the pore characteristics of coal, taking remolded coal as the research object, the mercury intrusion method was used to determine the pore structures of the briquettes under the compression loads of 50, 70, 90 and 110 MPa, and the Menger sponge model was used to conduct fractal research on the measured parameters. The results show that the compression load has a significant effect on the pore structure parameters of the briquettes. The hysteresis loop generated by the mercury-intrusion and mercury-extrusion curves of raw coal is small, and the pore connectivity is better. After different loads are applied for briquettes, the hysteresis loop becomes larger, and the pore connectivity becomes worse. From the process of the raw coal to the briquettes loaded at 50 and 70 MPa, the pore-specific surface area reduced from 5.069 m2/g to 1.259 m2/g, the total pore volume increased from 0.0553 cm3/g to 0.1877 cm3/g, and the average pore size increased from 43.6 nm to 596.3 nm. When the compression load reached 70 MPa, the specific surface area, total pore volume, and average pore diameter of briquettes remained basically stable with the change in the compression load. The minipores and visible pores and fissures of raw coal contribute 78% of the pore volume, and the micropores and minipores contribute 99% of the specific surface area. After being pressed into briquettes, the volume of mesopores and macropores increases, the volume of visible pores and fractures decreases and the volume of minipores changes little; additionally, the pore surface area contributed by mesopores and macropores increases, and the pore surface area contributed by micropores decreases, indicating that the effect of compression load on pores of 10–100 nm is not obvious, mainly concentrated in the 100–10,000 nm region. The fractal curve of briquettes is fitted into three sections, which are defined as low-pressure sections 1 and 2 and high-pressure section 3, and the fractal dimensions are D1, D2 and D3 respectively. The fractal dimension D1 of briquettes with different compression loads is close to 2, D2 is close to 3 and D3 is greater than 3. The pore structures of briquettes have obvious fractal characteristics in the low-pressure sections 1 and 2 but do not conform to the fractal law in the high-pressure section. Furthermore, in the micropore stage of briquettes, the measured surface area and volume are both negative, indicating that the mercury intrusion method used to test the pore structure of the loaded briquette is more likely to cause the collapse of and damage to the pores in the micropore (<10 nm) stage.

An adsorption model for cylindrical pore and its method to calculate pore size distribution of coal by combining NMR

Coalbed methane (CBM) adsorption is closely related to pore size distribution in coal, the study of its adsorption state and pore characteristics of coal are of great significance to its exploitation and storage. In this paper, an extended simplified local density adsorption (SLD) model is proposed, which can be applied to cylindrical pores. Combining with the nuclear magnetic resonance (NMR) tests, the extended SLD model can predict the adsorption amount and pore size distribution of the whole sample without destroying its original pore structure. Three coal samples collected from different areas are selected for NMR test to measure T2 distribution and Magnetic Resonance Imaging (MRI) image. Then, the adsorption amount of the samples are obtained under constant temperature and different pressures. The fitting coefficients of the extend SLD model and experimental data of the three samples are all greater than 0.99, indicating that the proposed model matches the experimental results well. The two parameters obtained by fitting, transverse surface relaxivity (K) and the total number of pore (N), combined with T2, can get the radius and number of each pore in the sample. The inversion results show that the number summation of micropores and mesopores of the three samples are all exceeds 99%. However, due to the small pore size of micropores and mesopores, the pore volume summation of the three coal samples occupied by fractures and macropores are all over 27%. Further observation of cylindrical pore size and fluid molecular position shows that the distance between fluid-solid molecules is the main factor affecting the adsorption. The results of this paper are beneficial to predict and calculate the adsorption amount and pore size distribution of coal.

Experimental Study on the Pore Structure of Middle- and Low-Rank Coal and Its Influence on Methane Adsorption

The pore characteristics of coal have an important influence on the coal adsorption of methane. The liquid nitrogen adsorption method was used to study the pore structure of low- and middle-rank coal samples from two aspects: pore specific surface area and pore shape. Low-field nuclear magnetic resonance (NMR) technology was used to study the difference in methane adsorption of coal samples under the same adsorption conditions. The influence and mechanism of the pore structure of middle- and low-rank coal samples on gas adsorption are discussed and analyzed. The results show the following: (1) There are differences in the adsorption capacity of medium- and low-rank coal samples. Within 1 h of methane inflation, the methane adsorption capacity of middle-rank coals such as Henan Pingdingshan (PDS) and Shanxi Wangzhuang (WZ) and Xinjiang low-rank coals (XJ) increases by 36.4%, 31.7%, and 35.8%, respectively, and as the inflation time is extended to the cumulative inflation of 10 h, the order of the increase in methane adsorption capacity is still PDS>XJ>WZ. (2) The pore types of the experimental coal samples are mostly wedge-shaped pores and ink bottle-shaped pores. The order of the BET specific surface area of the coal samples is in the order of WZ>PDS> XJ, which means that the WZ samples can provide more adsorption sites for gas molecule adsorption, but under the same adsorption conditions, the WZ sample has the least amount of gas adsorbed. Further analysis shows that the order of the tortuosity of the coal sample is WZ>XJ>PDS, which means that the WZ sample has a large pore tortuosity, a long channel for methane molecules to diffuse into the internal pores of the coal sample, and large diffusion resistance. It is the main reason why the methane adsorption capacity of WZ coal samples is less than that of PDS and XJ coal samples in the same adsorption conditions.

Effects of Pore Structure of Different Rank Coals on Methane Adsorption Heat

Adsorption thermodynamic characteristics are an important part of the methane adsorption mechanism, and are useful for understanding the energy transmission mechanism of coalbed methane (CBM) migration in coal reservoirs. To study the effect of coal pore characteristics on methane adsorption heat, five different types of rank coals were used for low-pressure nitrogen, low-pressure carbon dioxide, and methane adsorption experiments. Pore structure and adsorption parameters, including maximum adsorption capacity and adsorption heat, were obtained for five coal samples, and their relationships were investigated. The results show that the low-pressure nitrogen adsorption method can measure pores within 1.7–300 nm, while the low-pressure carbon dioxide adsorption method can measure micropores within 0.38–1.14 nm. For the five coal samples, comprehensive pore structure parameters were obtained by combining the results of the low-pressure nitrogen and carbon dioxide adsorption experiments. The comprehensive results show that micropores contribute the most to the specific surface area of anthracite, lean coal, fat coal, and lignite, while mesopores contribute the most to the specific surface area of coking coal. Mesopores contribute the most to the pore volume of the five coal samples. The maximum adsorption capacity has a significant positive correlation with the specific surface area and pore volume of micropores less than 2 nm, indicating that methane is mainly adsorbed on the surface of micropores, and can also fill the micropores. The adsorption heat has a significant positive correlation with the specific surface area and pore volume of micropores within 0.38–0.76 nm, indicating that micropores in this range play a major role in determining the methane adsorption heat.

Laboratory investigation on pore characteristics of coals with consideration of various tectonic deformations

Coal structure is highly related to paleo-stress variation and the pore structure of coals can be modified through tectonic activities. This study characterizes the pore structure variations for various coal samples with different tectonic deformation intensities. The low temperature N2 and pressure CO2 adsorption analyses were conducted to quantify the pore structures, and high pressure CH4 adsorption measurements were carried out for the sorption analysis. The pores were classified into ultramicropores (<2 nm), micropores (2–10 nm), mesopores (10–100 nm) and macropores (>100 nm). The results show that with the increase of coal deformation intensity, the proportion of pore size of 50–300 nm decreased, showing that more macropores and mesopores were deformed to the smaller pores (<50 nm). Micropores (2–10 nm) in granulated and mylonitic coals obviously increased. The predominant ultramicropore in four kinds of coal structures were distributed at the range of 0.45–0.6 nm and 0.80–1.0 nm. Tectonic coals formed more ultramicropores lower than 0.65 nm. The adsorption of CH4, N2 and CO2 increased as the coal deformation degree increased, following the order: mylonitic coal > granulated coal > cataclastic coal > intact coal. Fractal dimensions show that tectonic coals characterized the rougher pore surface (higher D1) and more homogeneous pore structures (lower D2), which led to the higher adsorption capacity. The development of micropores was positive with Langmuir VL, but the ultramicropore SSAs were significantly larger than the contribution to SSAs of micropores and mesopores. Thus, ultramicropore provided the main adsorption sites for CH4. The variations of adsorption potential increased with the coal deformation intensity increased, and the smaller the adsorption space volume was, the larger adsorption potential would be, illustrating that adsorption in micropores was higher than mesopores and macropores. Tectonic coals have the higher reduced rate of cumulative surface free energy, which shows that tectonic damages promote the adsorption potential and surface free energy in coals.

Surface fractal dimensions as a characterization parameter for methane adsorption–induced coal strains

Pore network in coal is important for coal bed methane storage, making it necessary for us to further study coal pore characteristics for better studying and exploiting the coal bed methane resource, also reducing the gas outburst accidents during coal mining process. In this paper, adsorption strain experiments were implemented to distinguish the differences of methane adsorption effects of coal samples directly. A series of pore character experiments of coal samples, mercury intrusion porosimetry, and nitrogen/carbon dioxide adsorption experiments were implemented to obtain the pore distribution. Based on mercury intrusion porosimetry and nitrogen adsorption experiments’ data, surface fractal dimensions were calculated by the fractal method. The relation between surface fractal dimensions and coal volumetric strains due to methane adsorption was analyzed. It turns out that the surface fractal dimension, as a comprehensive parameter describing the pore distribution characteristic, is positively correlated with coal adsorption strain and Langmuir adsorption parameters.

Multiscale Experiments and Multifractal Analysis of Bituminous Coals: Dominant Pore Properties for Gas Permeability

Abstract The pore characteristics of coal are highly correlated with gas permeability. In this study, multifractal analysis based on mercury intrusion porosimetry (MIP) was used to investigate the pore spatial distributions and heterogeneity of pore size distributions (PSDs) of three sister coal samples collected from the Xin Zhouyao mine in China. The mercury intrusion data, under pressures of over 10 MPa, were corrected in combination with the gas adsorption results. All CT images were processed by using the Image-Pro Plus® (IPP) software (Media Cybernetics, Inc., Rockville, MD). The pore volume percentage information obtained from the MIP was found to be coincident with the 3D reconstructions. Seepage experiments were also carried out under different gas pressures to analyze the effect of the pore parameters on permeability. The results from these experiments showed that for the three coal samples, the degree of clustering of the pores is the dominant factor for permeability and should be the first factor considered. Variations of μ (q, ϵ) versus ϵ indicated that the PSDs of coals have multifractal behavior. Multifractal analysis was suggested by the extracted parameters from the PSDs, including the capacity dimension D0, the information dimension D1, the correlation dimension D2, the widths of the right side D0–D10, and of the left side D−10–D0 of Dq spectra, and the widths of left side α0–αq+ and right side α0–αq− of the f (α) spectrum. These parameters were further discussed to evaluate the permeability.

Coal pore characteristics in different coal mine dynamic disasters

The pore characteristics of coal have an important influence on the dynamic disaster of coal mine. Considering the disaster caused by large deformation of coal-rock mass, the influence of pore deformation and pore distribution also needs further study simultaneously. In this paper, the pore characteristics of gas outburst coal and bursting liability coal are analyzed and compared. The pore structure, the pore volume, and the pore compressibility associated with different dynamic disasters were comprehensively analyzed. The experimental data of mercury intrusion were corrected by liquid nitrogen adsorption experiment data, and the distribution of pore volume was obtained. Moreover, the fractal dimension of partial micropore was calculated, and the pore compressibility of coal was determined according to the fractal dimension. The results show that there are great differences in the pore characteristics between outburst coal and impact proneness coal, which are also one of the factors leading to different disasters in coal mine.

Coal pore characteristics at different freezing temperatures under conditions of freezing–thawing cycles

Most coal reservoirs in China have low permeability, which causes gas drainage to be inefficient. The method of cyclic cryogenic fracturing basing on freezing–thawing (F–T) fracturing effects is proposed to break coal to increase its permeability. An F–T experiment was carried out at different freezing temperatures using a nuclear magnetic resonance (NMR) test and an ultrasonic test. We investigated the evolution of coal pore structure under different freezing temperature F–T cycles and the mechanism of F–T fracturing. The results indicate that the frost force and the thermal stress in the cyclical process of F–T work together to cause fracture formation and fatigue damage. When the freezing temperature decreases, the network of pores and fissures becomes more developed and the number of mesopores, macropores and micro-fractures increases. This suggests that the network of pore-fractures in coal will be more interconnected and the space available for gas seepage will be larger. Ultimately, this significantly increases the efficiency of gas drainage.

Effect of high-voltage thermal breakdown on pore characteristics of coal

High-voltage thermal breakdown has great potential application in permeability enhancement of coal seam. The characteristics of the breakdown channel, coal element, porosity and microscopic coal petrography of coal under high-voltage electric load were experimentally studied. The coal interior left apparent tracks due to electric current burning with high temperature. The percentage of C, O, Al, Fe, and Si had slightly decreased, while the content of element N increased obviously. Low-pressure nitrogen gas adsorption (LP-N2GA) and mercury intrusion analysis showed that coal porosity increased. The increases of micropores and mesopores are beneficial to promotion of the ability of gas storage, and the increase of macropores could enhance the gas seepage and migration. The results of scanning electron microscope (SEM) show that there are many exogenous fractures in coal, which is also beneficial to gas seepage and migration. The results lay a theoretical foundation for application of high-voltage thermal breakdown in coal mines.

The effects of different experimental conditions on the detected results of coal pore characteristics

Low-temperature nitrogen adsorption-desorption experiment based on static volumetric method is widely used to analyze the pore characteristics of coal. The pore structure of a middle rank coking coal produced in Shanxi Province, China is analyzed. The effects of different experimental conditions including degassing time, degassing temperature, sample weight, and sample particle size on the detected pore characteristics of coal are studied to obtain the best optimized experimental conditions. The results indicate that the optimal experimental conditions include degassing time of at least 8 h, degassing temperature of around 150°C, 5000.0 mg sample weight, and <0.5 mm particle size. Pore size distribution of coal samples is calculated from the adsorption branch and desorption branch isotherms by using the Barrett–Joyner–Halenda (BJH) analysis method and De Boer (DB) method. Moreover, the optimum means are obtained from the BJH method within the adsorption branch and the DB method within the desorption branch.

Effect of magmatic intrusion on coal pore characteristics and fractal research

The pore characteristics in magmatic intruded coals are closely related to the absorption-desorption and the flow of Coalbed Methane (CBM) in coal seams. Coal samples with different degrees of magmatic intrusion are tested using the method of mercury intrusion porosimetry (MIP). A number of parameters, such as the pore diameter, the volume, the connectivity and the specific surface area, are investigated. In addition, the fractal theory is introduced as a new approach to characterize the pore characteristics in intruded coals by calculating the fractal dimensions. The correlation between the fractal dimension and the inherent moisture content is also discussed. The results indicate that 1) when the coal approaches the magma, the pore size, the pore volume, the open pores and pore connectivity increase, but the total specific surface area exhibit decline trends; 2) the calculated fractal dimension can demonstrate the above characteristics; 3) a significant relationship between the inherent moisture content and the fractal dimension can be established. The research findings in this paper provide a useful fundamental knowledge to guide future studies of CBM development or gas outburst for intruded coals.

An investigation of the evaporation behavior of bioliquid in the pores and its application to hybrid coal combining biomass with coal

In this study, the evaporation temperature behaviors of various liquids in silica and activated carbon pores were investigated, and applicability of bioliquid in coal pores was reported. In countries around the world, to reduce the potential carbon dioxide, solid phase biomasses, such as wood chips and pellets, have been mixed with coal to make fuel for coal-fired power plants. However, the liquid phase biomass (bioliquid) has a phase different from coal in atmospheric conditions and evaporates at a relatively low temperature. As a result, it has been difficult to use biomass in the existing coal-fired power plants due to a number of problems, such as fuel injection, the reduction of combustion efficiency in coal, spontaneous combustion, and the risk of explosion during drying. To address these challenges, evaporation behaviors of bioliquids were evaluated using silica and activated carbon that have various pores and surface characteristics. The impregnation of bioliquids was accelerated on a support that had the same hydrophilic or hydrophobic characteristics, and the evaporation temperature increased at the hydrophilic surfaces or in small pores. In addition, evaporation behaviors were assessed by filling bioliquids into coal pores that originated from ash and fixed carbon. These results increase understanding of coal pore characteristics and will enable better choices of bioliquids that can be used together with coal in the existing coal-fired power plants.