Wall slip is a microscopic phenomenon of cemented paste backfill(CPB)slurry near the pipe wall,which has an important influence on the form of slurry pipe transport flow and velocity distribution.Directly probing the ...Wall slip is a microscopic phenomenon of cemented paste backfill(CPB)slurry near the pipe wall,which has an important influence on the form of slurry pipe transport flow and velocity distribution.Directly probing the wall slip characteristics using conventional experimental methods is difficult.Therefore,this paper established a noncontact experimental platform for monitoring the microscopic slip layer of CPB pipeline transport independently based on particle image velocimetry(PIV)and analyzed the effects of slurry temperature,pipe diameter,solid concentration,and slurry flow on the wall slip velocity of the CPB slurry,which refined the theory of the effect of wall slip characteristics on pipeline transport.The results showed that the CPB slurry had an extensive slip layer at the pipe wall with significant wall slip.High slurry temperature improved the degree of particle Brownian motion within the slurry and enhanced the wall slip effect.Increasing the pipe diameter was not conducive to the formation of the slurry slip layer and led to a transition in the CPB slurry flow pattern.The increase in the solid concentration raised the interlayer shear effect of CPB slurry flow and the slip velocity.The slip velocity value increased from 0.025 to 0.056 m·s^(-1)when the solid content improved from 55wt%to 65wt%.When slurry flow increased,the CPB slurry flocculation structure changed,which affected the slip velocity,and the best effect of slip layer resistance reduction was achieved when the transported flow rate was 1.01 m^(3)·h^(-1).The results had important theoretical significance for improving the stability and economy of the CPB slurry in the pipeline.展开更多
When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpow...When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpower needed for maintenance but also disrupts the use of the waterfalls.Therefore,it is necessary to design a new type of artificial waterfall that is suitable for gardens.The waterfall should incorporate features that make cleaning easier,including filter plates and water funnels to prevent clogging caused by fallen leaves and debris.展开更多
The high number of leak events that took place in recent years at a 25.4 cm (10”)Øpipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a numb...The high number of leak events that took place in recent years at a 25.4 cm (10”)Øpipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.展开更多
In response to the lack of global quantitative research on the potential and scale prediction of CO_(2) capture,utilization and storage(CCUS)in China under the background of carbon peak and carbon neutrality goals,thi...In response to the lack of global quantitative research on the potential and scale prediction of CO_(2) capture,utilization and storage(CCUS)in China under the background of carbon peak and carbon neutrality goals,this study predicts the future economic costs of different links of ccUS technologies and the carbon capture needs of different industries in the scenario of fossil energy continuation.Based on the CO_(2) utilization and storage potential and spatial distribution in China,a cost-scale calculation model for different regions in China in 206o is constructed to predict the whole-process economic cost and its corresponding scale potential of CCUs.The results show that a local+remote storage mode is preferred,together with a local utilization mode,to meet China's 27×10^(8)t/a CO_(2) emission reduction demand under the scenario of fossil energy continuation.Specifically,about 5×10^(8) t CO_(2) emission is reduced by capture utilization,and the whole-process cost is about-1400-200 RMB/t;about 22×10^(8) t CO_(2) emission is reduced by capture storage,and the whole-process cost is about 200-450 RMB/t.According to the model results,it is recommended to develop the chemical utilization industry based on P2X(Power to X,where X is raw material)technology,construct the CcUs industrial cluster,and explore a multi-party win-win cooperation mode.A scheme of national trunk pipeline network connecting areas connecting intensive emission reduction demand areas and target storage areas is suggested.The emission reduction cost of thermal power based on CCUS is calculated to be 0.16 RMB/(kW.h).展开更多
Cemented paste backfill(CPB)has been one of the best practical approaches for tailings management and underground goaf treatment.Paste rheology is a science to study the flow and deformation behaviors of paste or fill...Cemented paste backfill(CPB)has been one of the best practical approaches for tailings management and underground goaf treatment.Paste rheology is a science to study the flow and deformation behaviors of paste or filling body under the effects of stress,strain,temperature,and time during the CPB process.The goal of studying paste rheology is to solve the engineering problems existing in four key processes;that is,paste rheology should meet the engineering demands of thickening,mixing,transportation,and backfilling.However,paste rheology is extremely complicated due to its high concentration,materials complexity,and engineering characteristics of non-stratification,nonsegregation,and non-bleeding.The rheological behavior of full tailings in deep thickening,rheological behavior of paste in mixing and pipeline transportation,and rheological behavior of filling body are introduced and discussed:(1)gel point,compressive yield stress,and the hindered settling function are adopted to characterize the rheological properties of full tailings in deep thickening.Combination of Coe-Clevenger theory and Buscall-White theory can also analyze the thickening performance in the whole area of deep cone thickener;(2)yield stress and viscosity are consistent with the evolution trend of the relative structure coefficient of paste in mixing;(3)coupling effect of wall slip and time-temperature dependency has a significant influence on the rheological properties and pipeline transportation;(4)damage variable is introduced to the Burgers model to describe the creep damage of the filling body.However,in-depth and systematic studies were still needed to establish a complete theoretical system of paste rheology in metal mines.展开更多
Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transpo...Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transportation systems.Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop(SJTU-HMSPD)pipeline-resistance-calculation model,the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system.The said system demonstrates a uniformity coefficient in the 1.26–7.98 range,median particle size of 0.075–4 mm,particle volume concentration of 10–60%,and pipeline diameter of 0.203–0.8 m.The results obtained were successfully verified against existing experimental data.The influence of parameters,such as particle-gradation uniformity coefficient,median particle size,pipe diameter,and particle volume concentration,on the SPC were analysed.The results revealed that the greater is the uniformity coefficient,the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant,median particle size slurry.As observed,the optimal transport concentration for broad-graded sand equalled approximately 48%.These results supplement the conclusions of existing research,indicating that the optimal transport concentration is approximately 30%and provides theoretical support for high concentration transportation of broad graded slurry.展开更多
Super-speed rail (SSR) is a kind of train design based on the theory of vacuum pipeline transportation, having the advantages of superspeed, high safety, low energy consumption, low noise, no vibration and no pollutio...Super-speed rail (SSR) is a kind of train design based on the theory of vacuum pipeline transportation, having the advantages of superspeed, high safety, low energy consumption, low noise, no vibration and no pollution. SSR may be a new generation of trains after cars,ships, trains and aeroplanes. The SSR system includes two parts, namely vacuum pipe technology and magnetic levitation technology.Based on the definition of SSR, the present paper analyses the operation principle of SSR. According to distribution characteristicsof SSR, the evaluation index system of SSR was set up. In analysing the main characteristics of SSR, this paper builds the evaluationmodel by improved value function. The application results validate the feasibility of the new method in comprehensive evaluationfor SSR. It is consistent with the results of other methods. The result reveals that SSR is completely feasible from a theoretical pointof view and it is impossible to build SSR in a short time from the application perspective. The evaluation results can reflect the actualsituation. The comprehensive evaluation model is scientific and the process is simple。展开更多
In a previous work it has been shown that a one-dimensional,hyperbolic,transient five equations twofluid model is able to numerically describe stratified,wavy,and slug flow in horizontal and nearhorizontal pipes.Slug ...In a previous work it has been shown that a one-dimensional,hyperbolic,transient five equations twofluid model is able to numerically describe stratified,wavy,and slug flow in horizontal and nearhorizontal pipes.Slug statistical characteristics can be numerically predicted with results in good agreement with experimental data and well-known empirical relations.In this model some approximated and simplified assumptions are adopted to describe shear stresses at wall and at phase interface.In this paper,we focus on the possibility to account for the cross sectional flow by inserting shape factors into the momentum balance equations of the aforementioned model.Velocity profiles are obtained by a pre-integrated model and they are computed at each time step and at each computational cell.Once that the velocity profiles are known,the obtained shape factors are inserted in the numerical resolution.In this way it is possible to recover part of the information lost due to the one-dimensional flow description.Velocity profiles computed in stratified conditions are compared against experimental profiles measured by PIV technique;a method to compute the velocity profile during slug initiation and growth has been developed and the computed velocity distribution in the liquid phase was compared against the one-seventh power law.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.51774137 and 51804121)。
文摘Wall slip is a microscopic phenomenon of cemented paste backfill(CPB)slurry near the pipe wall,which has an important influence on the form of slurry pipe transport flow and velocity distribution.Directly probing the wall slip characteristics using conventional experimental methods is difficult.Therefore,this paper established a noncontact experimental platform for monitoring the microscopic slip layer of CPB pipeline transport independently based on particle image velocimetry(PIV)and analyzed the effects of slurry temperature,pipe diameter,solid concentration,and slurry flow on the wall slip velocity of the CPB slurry,which refined the theory of the effect of wall slip characteristics on pipeline transport.The results showed that the CPB slurry had an extensive slip layer at the pipe wall with significant wall slip.High slurry temperature improved the degree of particle Brownian motion within the slurry and enhanced the wall slip effect.Increasing the pipe diameter was not conducive to the formation of the slurry slip layer and led to a transition in the CPB slurry flow pattern.The increase in the solid concentration raised the interlayer shear effect of CPB slurry flow and the slip velocity.The slip velocity value increased from 0.025 to 0.056 m·s^(-1)when the solid content improved from 55wt%to 65wt%.When slurry flow increased,the CPB slurry flocculation structure changed,which affected the slip velocity,and the best effect of slip layer resistance reduction was achieved when the transported flow rate was 1.01 m^(3)·h^(-1).The results had important theoretical significance for improving the stability and economy of the CPB slurry in the pipeline.
文摘When artificial waterfalls are built in gardens,leaves from trees or vegetation often fall into the water storage pool and block the pipelines,requiring regular cleaning of pipelines.This not only increases the manpower needed for maintenance but also disrupts the use of the waterfalls.Therefore,it is necessary to design a new type of artificial waterfall that is suitable for gardens.The waterfall should incorporate features that make cleaning easier,including filter plates and water funnels to prevent clogging caused by fallen leaves and debris.
文摘The high number of leak events that took place in recent years at a 25.4 cm (10”)Øpipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.
基金Supported by the National Natural Science Foundation of China(72140006)GEIDCO Independent Research Project(ZY2023008).
文摘In response to the lack of global quantitative research on the potential and scale prediction of CO_(2) capture,utilization and storage(CCUS)in China under the background of carbon peak and carbon neutrality goals,this study predicts the future economic costs of different links of ccUS technologies and the carbon capture needs of different industries in the scenario of fossil energy continuation.Based on the CO_(2) utilization and storage potential and spatial distribution in China,a cost-scale calculation model for different regions in China in 206o is constructed to predict the whole-process economic cost and its corresponding scale potential of CCUs.The results show that a local+remote storage mode is preferred,together with a local utilization mode,to meet China's 27×10^(8)t/a CO_(2) emission reduction demand under the scenario of fossil energy continuation.Specifically,about 5×10^(8) t CO_(2) emission is reduced by capture utilization,and the whole-process cost is about-1400-200 RMB/t;about 22×10^(8) t CO_(2) emission is reduced by capture storage,and the whole-process cost is about 200-450 RMB/t.According to the model results,it is recommended to develop the chemical utilization industry based on P2X(Power to X,where X is raw material)technology,construct the CcUs industrial cluster,and explore a multi-party win-win cooperation mode.A scheme of national trunk pipeline network connecting areas connecting intensive emission reduction demand areas and target storage areas is suggested.The emission reduction cost of thermal power based on CCUS is calculated to be 0.16 RMB/(kW.h).
基金financially supported by the National Natural Science Foundation of China(Nos.52130404 and 51774039)the Project funded by China Postdoctoral Science Foundation(No.2021M690011)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2021A 1515110161)the Postdoctor Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(No.2021BH011)。
文摘Cemented paste backfill(CPB)has been one of the best practical approaches for tailings management and underground goaf treatment.Paste rheology is a science to study the flow and deformation behaviors of paste or filling body under the effects of stress,strain,temperature,and time during the CPB process.The goal of studying paste rheology is to solve the engineering problems existing in four key processes;that is,paste rheology should meet the engineering demands of thickening,mixing,transportation,and backfilling.However,paste rheology is extremely complicated due to its high concentration,materials complexity,and engineering characteristics of non-stratification,nonsegregation,and non-bleeding.The rheological behavior of full tailings in deep thickening,rheological behavior of paste in mixing and pipeline transportation,and rheological behavior of filling body are introduced and discussed:(1)gel point,compressive yield stress,and the hindered settling function are adopted to characterize the rheological properties of full tailings in deep thickening.Combination of Coe-Clevenger theory and Buscall-White theory can also analyze the thickening performance in the whole area of deep cone thickener;(2)yield stress and viscosity are consistent with the evolution trend of the relative structure coefficient of paste in mixing;(3)coupling effect of wall slip and time-temperature dependency has a significant influence on the rheological properties and pipeline transportation;(4)damage variable is introduced to the Burgers model to describe the creep damage of the filling body.However,in-depth and systematic studies were still needed to establish a complete theoretical system of paste rheology in metal mines.
基金This research was supported by the National Natural Science Foundation of China(Grant No.51779143)the Cultivation of Scientific Research Ability of Young Talents of Shanghai jiao Tong University(Grant No.19×100040072).
文摘Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transportation systems.Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop(SJTU-HMSPD)pipeline-resistance-calculation model,the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system.The said system demonstrates a uniformity coefficient in the 1.26–7.98 range,median particle size of 0.075–4 mm,particle volume concentration of 10–60%,and pipeline diameter of 0.203–0.8 m.The results obtained were successfully verified against existing experimental data.The influence of parameters,such as particle-gradation uniformity coefficient,median particle size,pipe diameter,and particle volume concentration,on the SPC were analysed.The results revealed that the greater is the uniformity coefficient,the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant,median particle size slurry.As observed,the optimal transport concentration for broad-graded sand equalled approximately 48%.These results supplement the conclusions of existing research,indicating that the optimal transport concentration is approximately 30%and provides theoretical support for high concentration transportation of broad graded slurry.
基金the National Natural Science Founda-tion of China(Grant No.51178157)the Key Science and Tech-nology Program in Henan province(Grant No.182102310004).
文摘Super-speed rail (SSR) is a kind of train design based on the theory of vacuum pipeline transportation, having the advantages of superspeed, high safety, low energy consumption, low noise, no vibration and no pollution. SSR may be a new generation of trains after cars,ships, trains and aeroplanes. The SSR system includes two parts, namely vacuum pipe technology and magnetic levitation technology.Based on the definition of SSR, the present paper analyses the operation principle of SSR. According to distribution characteristicsof SSR, the evaluation index system of SSR was set up. In analysing the main characteristics of SSR, this paper builds the evaluationmodel by improved value function. The application results validate the feasibility of the new method in comprehensive evaluationfor SSR. It is consistent with the results of other methods. The result reveals that SSR is completely feasible from a theoretical pointof view and it is impossible to build SSR in a short time from the application perspective. The evaluation results can reflect the actualsituation. The comprehensive evaluation model is scientific and the process is simple。
文摘In a previous work it has been shown that a one-dimensional,hyperbolic,transient five equations twofluid model is able to numerically describe stratified,wavy,and slug flow in horizontal and nearhorizontal pipes.Slug statistical characteristics can be numerically predicted with results in good agreement with experimental data and well-known empirical relations.In this model some approximated and simplified assumptions are adopted to describe shear stresses at wall and at phase interface.In this paper,we focus on the possibility to account for the cross sectional flow by inserting shape factors into the momentum balance equations of the aforementioned model.Velocity profiles are obtained by a pre-integrated model and they are computed at each time step and at each computational cell.Once that the velocity profiles are known,the obtained shape factors are inserted in the numerical resolution.In this way it is possible to recover part of the information lost due to the one-dimensional flow description.Velocity profiles computed in stratified conditions are compared against experimental profiles measured by PIV technique;a method to compute the velocity profile during slug initiation and growth has been developed and the computed velocity distribution in the liquid phase was compared against the one-seventh power law.
