Abstract The laminar combustion characteristics of CH 4 /air premixed flames with CO 2 addition are systemically studied. Experimental measurements and numerical simulations of the laminar burning velocity (LBV) are performed in CH 4 /CO 2 /Air flames with various CO 2 doping ratio under equivalence ratios of 1.0–1.4. GRI 3.0 mech and Aramco mech are employed for predicting LBV, adiabatic flame temperature (AFT), important intermediate radicals (CH 3 , H, OH, O) and NO x emissions (NO, NO 2 , N 2 O), as well as the sensitivity analysis is also conducted. The detail analysis of experiment and simulation reveals that as the CO 2 addition increases from 0% to 40%, the LBVs and AFTs decrease monotonously. Under the same CO 2 doping ratio, the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio, and the maximum of LBV is reached at equivalence ratio of 1.05. The mole fraction tendency of important intermediates and NO x with equivalence ratio and CO 2 doping ratio are similar to the LBVs and AFTs. Reaction H + O 2 ⇔ O + OH is found to be responsible for the promotion of the generation of important intermediates and NO x under the equivalence ratios and CO 2 addition through sensitivity analysis. The sensitivity coefficients of elementary reactions that the increasing of CO 2 doping ratio promotes or inhibits formation of intermediate radicals and NO x decreases. Graphical abstract
{"title":"Effect of CO2 dilution on laminar burning velocities, combustion characteristics and NOx emissions of CH4/air mixtures","authors":"Wenlong Dong, Longkai Xiang, Jian Gao, Bingbing Qiu, Huaqiang Chu","doi":"10.1007/s40789-023-00655-9","DOIUrl":"https://doi.org/10.1007/s40789-023-00655-9","url":null,"abstract":"Abstract The laminar combustion characteristics of CH 4 /air premixed flames with CO 2 addition are systemically studied. Experimental measurements and numerical simulations of the laminar burning velocity (LBV) are performed in CH 4 /CO 2 /Air flames with various CO 2 doping ratio under equivalence ratios of 1.0–1.4. GRI 3.0 mech and Aramco mech are employed for predicting LBV, adiabatic flame temperature (AFT), important intermediate radicals (CH 3 , H, OH, O) and NO x emissions (NO, NO 2 , N 2 O), as well as the sensitivity analysis is also conducted. The detail analysis of experiment and simulation reveals that as the CO 2 addition increases from 0% to 40%, the LBVs and AFTs decrease monotonously. Under the same CO 2 doping ratio, the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio, and the maximum of LBV is reached at equivalence ratio of 1.05. The mole fraction tendency of important intermediates and NO x with equivalence ratio and CO 2 doping ratio are similar to the LBVs and AFTs. Reaction H + O 2 ⇔ O + OH is found to be responsible for the promotion of the generation of important intermediates and NO x under the equivalence ratios and CO 2 addition through sensitivity analysis. The sensitivity coefficients of elementary reactions that the increasing of CO 2 doping ratio promotes or inhibits formation of intermediate radicals and NO x decreases. Graphical abstract","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"6 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136283983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-04DOI: 10.1007/s40789-023-00631-3
Yi Yang, Longxin Li, Xia Wang, Nan Qin, Ruihan Zhang, Yulong Zhao, Ye Tian
Abstract A simulation study was carried out to investigate the temporal evolution of H 2 S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H 2 S (27.2 g/m 3 ), and the lower layer Jia-1 contains a low concentration of H 2 S (14.0 mg/m 3 ). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H 2 S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H 2 S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H 2 S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H 2 S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H 2 S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H 2 S removal. After nine cycles, the produced gas’s H 2 S concentration can be lowered to 20 mg/m 3 . Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H 2 S concentration of the produced gas to 20 mg/m 3 , thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H 2 S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites.
{"title":"Simulation study of hydrogen sulfide removal in underground gas storage converted from the multilayered sour gas field","authors":"Yi Yang, Longxin Li, Xia Wang, Nan Qin, Ruihan Zhang, Yulong Zhao, Ye Tian","doi":"10.1007/s40789-023-00631-3","DOIUrl":"https://doi.org/10.1007/s40789-023-00631-3","url":null,"abstract":"Abstract A simulation study was carried out to investigate the temporal evolution of H 2 S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H 2 S (27.2 g/m 3 ), and the lower layer Jia-1 contains a low concentration of H 2 S (14.0 mg/m 3 ). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H 2 S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H 2 S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H 2 S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H 2 S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H 2 S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H 2 S removal. After nine cycles, the produced gas’s H 2 S concentration can be lowered to 20 mg/m 3 . Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H 2 S concentration of the produced gas to 20 mg/m 3 , thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H 2 S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"24 16","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135774182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-30DOI: 10.1007/s40789-023-00645-x
Canh Le Van, Cuong Xuan Cao, Anh Ngoc Nguyen, Chung Van Pham, Long Quoc Nguyen
Abstract Mining industrial areas with anthropogenic engineering structures are one of the most distinctive features of the real world. 3D models of the real world have been increasingly popular with numerous applications, such as digital twins and smart factory management. In this study, 3D models of mining engineering structures were built based on the CityGML standard. For collecting spatial data, the two most popular geospatial technologies, namely UAV-SfM and TLS were employed. The accuracy of the UAV survey was at the centimeter level, and it satisfied the absolute positional accuracy requirement of creating all levels of detail (LoD) according to the CityGML standard. Therefore, the UAV-SfM point cloud dataset was used to build LoD 2 models. In addition, the comparison between the UAV-SfM and TLS sub-clouds of facades and roofs indicates that the UAV-SfM and TLS point clouds of these objects are highly consistent, therefore, point clouds with a higher level of detail and accuracy provided by the integration of UAV-SfM and TLS were used to build LoD 3 models. The resulting 3D CityGML models include 39 buildings at LoD 2, and two mine shafts with hoistrooms, headframes, and sheave wheels at LoD 3.
{"title":"Building 3D CityGML models of mining industrial structures using integrated UAV and TLS point clouds","authors":"Canh Le Van, Cuong Xuan Cao, Anh Ngoc Nguyen, Chung Van Pham, Long Quoc Nguyen","doi":"10.1007/s40789-023-00645-x","DOIUrl":"https://doi.org/10.1007/s40789-023-00645-x","url":null,"abstract":"Abstract Mining industrial areas with anthropogenic engineering structures are one of the most distinctive features of the real world. 3D models of the real world have been increasingly popular with numerous applications, such as digital twins and smart factory management. In this study, 3D models of mining engineering structures were built based on the CityGML standard. For collecting spatial data, the two most popular geospatial technologies, namely UAV-SfM and TLS were employed. The accuracy of the UAV survey was at the centimeter level, and it satisfied the absolute positional accuracy requirement of creating all levels of detail (LoD) according to the CityGML standard. Therefore, the UAV-SfM point cloud dataset was used to build LoD 2 models. In addition, the comparison between the UAV-SfM and TLS sub-clouds of facades and roofs indicates that the UAV-SfM and TLS point clouds of these objects are highly consistent, therefore, point clouds with a higher level of detail and accuracy provided by the integration of UAV-SfM and TLS were used to build LoD 3 models. The resulting 3D CityGML models include 39 buildings at LoD 2, and two mine shafts with hoistrooms, headframes, and sheave wheels at LoD 3.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"145 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-27DOI: 10.1007/s40789-023-00654-w
Kang Tao, Wengang Dang, Xian Liao, Xingling Li
Abstract The frictional rupture mechanisms of rock discontinuities considering the dynamic load disturbance still remain unclear. This paper investigates the transitional behaviors of slip events happened on a planar granite fracture under cyclic normal stress with different oscillation amplitudes. The experimental results show that the activations of fast slips always correlate with unloading of normal stress. Besides, the intensive normal stress oscillation can weaken the shear strength which is recoverable when the normal stress return to constant. The rupture patterns are quantified by stress drop, slip length and slip velocity. With the effect of small oscillation amplitudes, the slip events show chaotic shapes, compared to the regular and predictable style under constant normal stress. When the amplitude is large enough, the big and small slip events emerge alternately, showing a compound slip style. Large amplitude of the cyclic normal stress also widens the interval differences of the slip events. This work provides experimental supports for a convincible link between the dynamic stress disturbance and the slip behavior of rock fractures.
{"title":"Experimental study on the slip evolution of planar fractures subjected to cyclic normal stress","authors":"Kang Tao, Wengang Dang, Xian Liao, Xingling Li","doi":"10.1007/s40789-023-00654-w","DOIUrl":"https://doi.org/10.1007/s40789-023-00654-w","url":null,"abstract":"Abstract The frictional rupture mechanisms of rock discontinuities considering the dynamic load disturbance still remain unclear. This paper investigates the transitional behaviors of slip events happened on a planar granite fracture under cyclic normal stress with different oscillation amplitudes. The experimental results show that the activations of fast slips always correlate with unloading of normal stress. Besides, the intensive normal stress oscillation can weaken the shear strength which is recoverable when the normal stress return to constant. The rupture patterns are quantified by stress drop, slip length and slip velocity. With the effect of small oscillation amplitudes, the slip events show chaotic shapes, compared to the regular and predictable style under constant normal stress. When the amplitude is large enough, the big and small slip events emerge alternately, showing a compound slip style. Large amplitude of the cyclic normal stress also widens the interval differences of the slip events. This work provides experimental supports for a convincible link between the dynamic stress disturbance and the slip behavior of rock fractures.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"59 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136261552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The physical and chemical properties of the air-dried residual coal after soaking in the goaf will change, resulting in an increase in its spontaneous combustion tendency. This study aimed to look into the features and mechanism of soaked-dried coal's spontaneous combustion. Five samples of coal were dried to various degrees, and the weight loss features during thermal processing were examined. Based on this, the pore structure and chemical structure characteristics of the coal samples with the highest tendency to spontaneous combustion were quantitatively examined, and the mechanism by which soaking-drying affected the spontaneous combustion heating process of the remaining coal in goaf was investigated in turn. The results show that T 1 decreases with the increase of drying time, T 2 –T 6 shows a fluctuating change, and the ignition activation energy of 36-S-Coal is smaller than that of other coal samples. The pore type of 36-S-Coal changes from a one-end closed impermeable pore to an open pore, and the pore group area is large. During the 36 h drying process, the internal channels of the coal were dredged, and a large number of gravels and minerals were precipitated from the pores with the air flow. A large number of gravels were around the pores to form a surface structure that was easy to adsorb various gases. Furthermore, infrared spectroscopy was used to analyze the two coal samples. It was found that soaking and drying did not change the functional group types of coal samples, but the fatty chain degree of 36-S-Coal was reduced to 1.56. It shows that the aliphatic chain structure of coal is changed after 36 h of drying after 30 days of soaking, which leads to the continuous shedding of aliphatic chain branches of residual coal, and the skeleton of coal is looser, which makes the low-temperature oxidation reaction of 36-S-Coal easier. Based on the above results, the coal-oxygen composite mechanism of water-immersed-dried coal is obtained, and it is considered that the key to the spontaneous combustion oxidation process of coal is to provide oxygen atoms and accelerate the formation of peroxides.
{"title":"Time-shift effect of spontaneous combustion characteristics and microstructure difference of dry-soaked coal","authors":"Yikang Liu, Haiyan Wang, Huiyong Niu, Tao Wang, Zhiwen Chen, Yuqi Chen, Qingjie Qi","doi":"10.1007/s40789-023-00616-2","DOIUrl":"https://doi.org/10.1007/s40789-023-00616-2","url":null,"abstract":"Abstract The physical and chemical properties of the air-dried residual coal after soaking in the goaf will change, resulting in an increase in its spontaneous combustion tendency. This study aimed to look into the features and mechanism of soaked-dried coal's spontaneous combustion. Five samples of coal were dried to various degrees, and the weight loss features during thermal processing were examined. Based on this, the pore structure and chemical structure characteristics of the coal samples with the highest tendency to spontaneous combustion were quantitatively examined, and the mechanism by which soaking-drying affected the spontaneous combustion heating process of the remaining coal in goaf was investigated in turn. The results show that T 1 decreases with the increase of drying time, T 2 –T 6 shows a fluctuating change, and the ignition activation energy of 36-S-Coal is smaller than that of other coal samples. The pore type of 36-S-Coal changes from a one-end closed impermeable pore to an open pore, and the pore group area is large. During the 36 h drying process, the internal channels of the coal were dredged, and a large number of gravels and minerals were precipitated from the pores with the air flow. A large number of gravels were around the pores to form a surface structure that was easy to adsorb various gases. Furthermore, infrared spectroscopy was used to analyze the two coal samples. It was found that soaking and drying did not change the functional group types of coal samples, but the fatty chain degree of 36-S-Coal was reduced to 1.56. It shows that the aliphatic chain structure of coal is changed after 36 h of drying after 30 days of soaking, which leads to the continuous shedding of aliphatic chain branches of residual coal, and the skeleton of coal is looser, which makes the low-temperature oxidation reaction of 36-S-Coal easier. Based on the above results, the coal-oxygen composite mechanism of water-immersed-dried coal is obtained, and it is considered that the key to the spontaneous combustion oxidation process of coal is to provide oxygen atoms and accelerate the formation of peroxides.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-26DOI: 10.1007/s40789-023-00605-5
Quanle Zou, Jinfei Zhan, Xin Wang, Zhen Huang
Abstract Gas drainage is an effective technology for gas control in coal mines. A high borehole-sealing quality is the fundamental precondition for efficient gas drainage. The expansibilities of cement pastes used in borehole-sealing processes are critical for the borehole-sealing effect. Nanosized magnesia expansive agents are used to improve the expansibilities of cement pastes and improve the borehole-sealing effect. Nuclear magnetic resonance spectrometry and scanning electron microscopy were adopted to study the effects of nanosized magnesia on the hydration of borehole-sealing cements used with different preparation methods. The results showed that an increase in the mass fraction of the nanosized magnesia promoted cement hydration, and the mass fraction was positively correlated with the promotion effect. The use of different preparation methods did not change the water-phase distribution in the cement. When using the wet-mixing preparation method, nanosized magnesia promoted the induction, acceleration, and deceleration periods of hydration; when using the dry-mixing preparation method, the nanosized magnesia promoted the induction period of cement hydration, and the promotion effect was less obvious than that seen when using the wet-mixing method. When using the wet-mixing preparation method, the nanosized magnesia was uniformly dispersed, thus enlarging the surface area of the reaction, which provided more nucleation sites for the hydration products of the cement and therefore accelerated the hydration reaction. When using the dry-mixing preparation method, the nanosized magnesia powders were dispersed nonuniformly and aggregated. Under these conditions, only a few nanosized magnesia particles on the surfaces of the aggregated clusters took part in hydration, so only a small number of nucleation sites were provided for the hydration products of cement. This led to inconsistent hydration of cement pastes prepared using the dry-mixing method. The surface porosity of the cement prepared with the wet-mixing preparation method first decreased and then increased with increases in the mass fraction of the nanosized magnesia. The cement surface exhibited compact hydration products and few pores, and the surface was relatively smooth. In comparison, the surface porosity of the cement prepared using the dry-mixing method fluctuated with increasing mass fraction of the nanosized magnesia, resulting in a rough cement surface and microfractures on some surfaces. The two preparation methods both reduced the surface porosity of the cement. The wet-mixing preparation was more effective and consistent in improving the compactness of the cement than the dry-mixing preparation. These results provide important guidance on the addition of nanosized magnesia in borehole-sealing engineering and the selection of cement preparation methods, and they also lay a solid foundation for realizing safe and efficient gas drainage.
{"title":"Influence of nanosized magnesia on the hydration of borehole-sealing cements prepared using different methods","authors":"Quanle Zou, Jinfei Zhan, Xin Wang, Zhen Huang","doi":"10.1007/s40789-023-00605-5","DOIUrl":"https://doi.org/10.1007/s40789-023-00605-5","url":null,"abstract":"Abstract Gas drainage is an effective technology for gas control in coal mines. A high borehole-sealing quality is the fundamental precondition for efficient gas drainage. The expansibilities of cement pastes used in borehole-sealing processes are critical for the borehole-sealing effect. Nanosized magnesia expansive agents are used to improve the expansibilities of cement pastes and improve the borehole-sealing effect. Nuclear magnetic resonance spectrometry and scanning electron microscopy were adopted to study the effects of nanosized magnesia on the hydration of borehole-sealing cements used with different preparation methods. The results showed that an increase in the mass fraction of the nanosized magnesia promoted cement hydration, and the mass fraction was positively correlated with the promotion effect. The use of different preparation methods did not change the water-phase distribution in the cement. When using the wet-mixing preparation method, nanosized magnesia promoted the induction, acceleration, and deceleration periods of hydration; when using the dry-mixing preparation method, the nanosized magnesia promoted the induction period of cement hydration, and the promotion effect was less obvious than that seen when using the wet-mixing method. When using the wet-mixing preparation method, the nanosized magnesia was uniformly dispersed, thus enlarging the surface area of the reaction, which provided more nucleation sites for the hydration products of the cement and therefore accelerated the hydration reaction. When using the dry-mixing preparation method, the nanosized magnesia powders were dispersed nonuniformly and aggregated. Under these conditions, only a few nanosized magnesia particles on the surfaces of the aggregated clusters took part in hydration, so only a small number of nucleation sites were provided for the hydration products of cement. This led to inconsistent hydration of cement pastes prepared using the dry-mixing method. The surface porosity of the cement prepared with the wet-mixing preparation method first decreased and then increased with increases in the mass fraction of the nanosized magnesia. The cement surface exhibited compact hydration products and few pores, and the surface was relatively smooth. In comparison, the surface porosity of the cement prepared using the dry-mixing method fluctuated with increasing mass fraction of the nanosized magnesia, resulting in a rough cement surface and microfractures on some surfaces. The two preparation methods both reduced the surface porosity of the cement. The wet-mixing preparation was more effective and consistent in improving the compactness of the cement than the dry-mixing preparation. These results provide important guidance on the addition of nanosized magnesia in borehole-sealing engineering and the selection of cement preparation methods, and they also lay a solid foundation for realizing safe and efficient gas drainage.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134909685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The structural integrity of mine dumps is crucial for mining operations to avoid adverse impacts on the triple bottom-line. Routine temporal assessments of coal mine dumps are a compliant requirement to ensure design reconciliation as spoil offloading continues over time. Generally, the conventional in-situ coal spoil characterisation is inefficient, laborious, hazardous, and prone to experts' observation biases. To this end, this study explores a novel approach to develop automated coal spoil characterisation using unmanned aerial vehicle (UAV) based optical remote sensing. The textural and spectral properties of the high-resolution UAV images were utilised to derive lithology and geotechnical parameters (i.e., fabric structure and relative density/consistency) in the proposed workflow. The raw images were converted to an orthomosaic using structure from motion aided processing. Then, structural descriptors were computed per pixel to enhance feature modalities of the spoil materials. Finally, machine learning algorithms were employed with ground truth from experts as training and testing data to characterise spoil rapidly with minimal human intervention. The characterisation accuracies achieved from the proposed approach manifest a digital solution to address the limitations in the conventional characterisation approach.
{"title":"Spoil characterisation using UAV-based optical remote sensing in coal mine dumps","authors":"Sureka Thiruchittampalam, Sarvesh Kumar Singh, Bikram Pratap Banerjee, Nancy F. Glenn, Simit Raval","doi":"10.1007/s40789-023-00622-4","DOIUrl":"https://doi.org/10.1007/s40789-023-00622-4","url":null,"abstract":"Abstract The structural integrity of mine dumps is crucial for mining operations to avoid adverse impacts on the triple bottom-line. Routine temporal assessments of coal mine dumps are a compliant requirement to ensure design reconciliation as spoil offloading continues over time. Generally, the conventional in-situ coal spoil characterisation is inefficient, laborious, hazardous, and prone to experts' observation biases. To this end, this study explores a novel approach to develop automated coal spoil characterisation using unmanned aerial vehicle (UAV) based optical remote sensing. The textural and spectral properties of the high-resolution UAV images were utilised to derive lithology and geotechnical parameters (i.e., fabric structure and relative density/consistency) in the proposed workflow. The raw images were converted to an orthomosaic using structure from motion aided processing. Then, structural descriptors were computed per pixel to enhance feature modalities of the spoil materials. Finally, machine learning algorithms were employed with ground truth from experts as training and testing data to characterise spoil rapidly with minimal human intervention. The characterisation accuracies achieved from the proposed approach manifest a digital solution to address the limitations in the conventional characterisation approach.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"14 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134908604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Mudstone, as a typical soft rock with wide distribution, has been endangering the slopes containing mudstone by its water-sensitivity of swelling and weakening strength when encountering water. To comprehensively understand the water-sensitivity of mudstone and reveal its influence on slope stability, we took the working slope containing water-sensitive mudstone of Shengli No.1 open-pit coal mine in Xilinhot, Inner Mongolia, China, as an example. Mudstone samples taken from the working slope were remodeled and saturated, and then triaxial tested to obtain the effective cohesion and effective internal friction angle. The filter paper method was used to obtain the soil–water characteristic curve of unsaturated mudstone. The pore structure of mudstone samples with different water contents were analyzed using the mercury intrusion porosimetry tests combined with the fractal dimension. The total pore content of the mudstone sample with lower water content is greater than that of the mudstone sample with higher water content. The mesopores are more in the mudstone sample with lower water content, while the small pores are more in the mudstone sample with higher water content. The variation of water content will change the complexity of mudstone pore structure. The higher the water content, the simpler the mudstone pore structure and the smoother the pore surface. Numerical calculations were conducted on the stability of the working slope under different rainfall conditions. The effective saturation on the mudstone layer surface changed and the plastic strain all occurred on the mudstone steps under different rainfall conditions. The key to preventing landslide of the slope containing water-sensitive mudstone in Shengli No.1 open-pit coal mine is to control the deformation and sliding of the mudstone layer.
{"title":"Stability analysis of a slope containing water-sensitive mudstone considering different rainfall conditions at an open-pit mine","authors":"Guoyu Yang, Yanlong Chen, Xuanyu Liu, Ri Yang, Yafei Zhang, Jialong Zhang","doi":"10.1007/s40789-023-00619-z","DOIUrl":"https://doi.org/10.1007/s40789-023-00619-z","url":null,"abstract":"Abstract Mudstone, as a typical soft rock with wide distribution, has been endangering the slopes containing mudstone by its water-sensitivity of swelling and weakening strength when encountering water. To comprehensively understand the water-sensitivity of mudstone and reveal its influence on slope stability, we took the working slope containing water-sensitive mudstone of Shengli No.1 open-pit coal mine in Xilinhot, Inner Mongolia, China, as an example. Mudstone samples taken from the working slope were remodeled and saturated, and then triaxial tested to obtain the effective cohesion and effective internal friction angle. The filter paper method was used to obtain the soil–water characteristic curve of unsaturated mudstone. The pore structure of mudstone samples with different water contents were analyzed using the mercury intrusion porosimetry tests combined with the fractal dimension. The total pore content of the mudstone sample with lower water content is greater than that of the mudstone sample with higher water content. The mesopores are more in the mudstone sample with lower water content, while the small pores are more in the mudstone sample with higher water content. The variation of water content will change the complexity of mudstone pore structure. The higher the water content, the simpler the mudstone pore structure and the smoother the pore surface. Numerical calculations were conducted on the stability of the working slope under different rainfall conditions. The effective saturation on the mudstone layer surface changed and the plastic strain all occurred on the mudstone steps under different rainfall conditions. The key to preventing landslide of the slope containing water-sensitive mudstone in Shengli No.1 open-pit coal mine is to control the deformation and sliding of the mudstone layer.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135351947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-05DOI: 10.1007/s40789-023-00623-3
A. N. Kozlov, E. P. Maysyuk, I. Yu. Ivanova
Abstract The purpose of this article is to receive environmental assessments of combustion of different types of coal fuel depending on the preparation (unscreened, size-graded, briquetted and heat-treated) in automated boilers and boilers with manual loading. The assessments were made on the basis of data obtained from experimental methods of coal preparation and calculated methods of determining the amount of pollutant and greenhouse gas emissions, as well as the mass of ash and slag waste. The main pollutants from coal combustion are calculated: particulate matter, benz(a)pyrene, nitrogen oxides, sulfur dioxide, carbon monoxide. Of the greenhouse gases carbon dioxide is calculated. As a result of conducted research it is shown that the simplest preliminary preparation (size-graded) of coal significantly improves combustion efficiency and environmental performance: emissions are reduced by 13% for hard coal and up to 20% for brown coal. The introduction of automated boilers with heat-treated coal in small boiler facilities allows to reduce emissions and ash and slag waste by 2–3 times. The best environmental indicators correspond to heat-treated lignite, which is characterized by the absence of sulfur dioxide emissions.
{"title":"Environmental performance assessments of different methods of coal preparation for use in small-capacity boilers: experiment and theory","authors":"A. N. Kozlov, E. P. Maysyuk, I. Yu. Ivanova","doi":"10.1007/s40789-023-00623-3","DOIUrl":"https://doi.org/10.1007/s40789-023-00623-3","url":null,"abstract":"Abstract The purpose of this article is to receive environmental assessments of combustion of different types of coal fuel depending on the preparation (unscreened, size-graded, briquetted and heat-treated) in automated boilers and boilers with manual loading. The assessments were made on the basis of data obtained from experimental methods of coal preparation and calculated methods of determining the amount of pollutant and greenhouse gas emissions, as well as the mass of ash and slag waste. The main pollutants from coal combustion are calculated: particulate matter, benz(a)pyrene, nitrogen oxides, sulfur dioxide, carbon monoxide. Of the greenhouse gases carbon dioxide is calculated. As a result of conducted research it is shown that the simplest preliminary preparation (size-graded) of coal significantly improves combustion efficiency and environmental performance: emissions are reduced by 13% for hard coal and up to 20% for brown coal. The introduction of automated boilers with heat-treated coal in small boiler facilities allows to reduce emissions and ash and slag waste by 2–3 times. The best environmental indicators correspond to heat-treated lignite, which is characterized by the absence of sulfur dioxide emissions.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134976235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.1007/s40789-023-00614-4
Zhongbei Li, Ting Ren, Dennis Black, Ming Qiao, Itmam Abedin, Jessica Juric, Mike Wang
Abstract The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO 2 composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components ( Q 1 , Q 2 , and Q 3 ) of the coal seam. The results show that in-situ total gas content ( Q T ) ranges from 9.48 m 3 /t for the A2 section to 14.80 m 3 /t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q 2 demonstrates the highest contribution to Q T , ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO 2 sorption behavior, with fit coefficients ( R 2 ) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content ( Q 3 ) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q 1 and Q 2 gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of effective gas management strategies and enhance the safety and efficiency of coal mining operations.
矿井瓦斯含量是评价煤与瓦斯突出潜力的关键。本研究重点研究了悉尼盆地具有代表性的A1、A2、A3多段煤层(CO 2成分超过90%)的煤层原煤含气量及瓦斯吸附能力。详细介绍了快速直接解吸法及其配套装置，并应用该方法对煤层中煤层气组分(q1、q2、q3)进行了原位测定。结果表明:A2段现场总含气量(Q T)为9.48 m 3 / T ~ A3段为14.80 m 3 / T，超过了2级突出阈值限值，需要采取抽放瓦斯措施;在气体组分中，q2对Q - T的贡献最大，在55% ~ 70%之间。在此基础上，对各煤层段煤样进行了高压等温气体吸附实验，探索煤样的气体吸附能力。Langmuir模型准确地描述了co2的吸附行为，拟合系数(r2)大于0.99。原位气体含量与Langmuir体积、残余气体含量(q3)与吸附滞回率呈显著正相关。值得注意的是，A3煤层区段q1和q2气体含量较高，吸附滞后较低，煤韧性f值较低，因此具有较高的突出倾向。从研究中获得的见解有助于制定有效的气体管理战略，提高煤矿开采作业的安全性和效率。
{"title":"In-situ gas contents of a multi-section coal seam in Sydney basin for coal and gas outburst management","authors":"Zhongbei Li, Ting Ren, Dennis Black, Ming Qiao, Itmam Abedin, Jessica Juric, Mike Wang","doi":"10.1007/s40789-023-00614-4","DOIUrl":"https://doi.org/10.1007/s40789-023-00614-4","url":null,"abstract":"Abstract The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO 2 composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components ( Q 1 , Q 2 , and Q 3 ) of the coal seam. The results show that in-situ total gas content ( Q T ) ranges from 9.48 m 3 /t for the A2 section to 14.80 m 3 /t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q 2 demonstrates the highest contribution to Q T , ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO 2 sorption behavior, with fit coefficients ( R 2 ) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content ( Q 3 ) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q 1 and Q 2 gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of effective gas management strategies and enhance the safety and efficiency of coal mining operations.","PeriodicalId":53469,"journal":{"name":"International Journal of Coal Science & Technology","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135407011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：