Ammonium sulfate residue is a particulate solid and is produced during the manufacture of ammonium sulfate fertilizer. The residue used in this study contained a large portion of calcium carbonate, from which active l...Ammonium sulfate residue is a particulate solid and is produced during the manufacture of ammonium sulfate fertilizer. The residue used in this study contained a large portion of calcium carbonate, from which active lime （CaO） was recovered via thermal decomposition. We used a purpose-built device to decom- pose the residue in a semi-suspension state. We found that CaO had the highest activity when residue was decomposed at 850-900 ~C. Our experiments indicated that ammonium sulfate residue should be decom- posed in a suspension state to produce active CaO. Based on our laboratory test findings, an industrial-scale production line with a high solid/gas ratio in a suspension state was devised. The optimal operating con- ditions for the decomposition of the ammonium sulfate residue to produce high quality CaO were also investigated.We found that the CaCO3 decomposition rate was high and the CaO product was highly active, averaging 170 s by the citric acid method. Morphology measurements showed that the CaO product had a porous structure and a large specific surface ensuring high activity.展开更多
YTB block in Sichuan basin is a favorable area to exploit oil and gas in shallow tight rock. 3D seismic project of this zone has two characteristics. Firstly, it has high requirements for the tolerance rate of the con...YTB block in Sichuan basin is a favorable area to exploit oil and gas in shallow tight rock. 3D seismic project of this zone has two characteristics. Firstly, it has high requirements for the tolerance rate of the construction process and the acquisition of high signal-to-noise ratio seismic data;Second, there are widely obstacles and noises that lead to difficult acquisition construction organization. In acquisition practice, high signal-to-noise ratio seismic data was obtained by reasonable design of construction scheme, optimization of excitation parameters, improvement of receiving conditions and optimization of obstacle crossing observation system. .展开更多
The dissolution kinetics of calcined ulexite in ammonium chloride solutions at high solid-to-liquid ratios were investigated. In the experiments, calcination temperature, solution concentration, reaction temperature, ...The dissolution kinetics of calcined ulexite in ammonium chloride solutions at high solid-to-liquid ratios were investigated. In the experiments, calcination temperature, solution concentration, reaction temperature, and pre-hydration were chosen as parameters. It was observed that the dissolution rate increased with increasing calcination temperature, solution concentration, and reaction temperature, whereas it was not affected by pre-hydration. Employing graphical and statistic methods, the dissolution rate, based on homogeneous reaction model, can be given as: (1-X(B2O3))-1-1= k(c(NH4Cl))1.982t. The activation energy for the dissolution of the ulexite sample calcined at 160 ℃ was found to be 84.04 kJ·mol-1.展开更多
In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of ...In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.展开更多
This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperatur...This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion.The ablation rate of ethylene-propylene-diene monomer(EPDM)insulator was measured after the experiment.Experimental results were analyzed through scanning electron microscopy and microcomputed tomography.The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results.The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform.The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation,and the ablation characteristic region is easily formed with the exfoliation of the charred layer.The ablation rate difference of the insulator increases with gas velocity.展开更多
A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,d...A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.展开更多
Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were carried out in an experimental test facility with the conveying pressure up to 4 MPa and the solid-gas ratio up to 450 kg·m-3....Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were carried out in an experimental test facility with the conveying pressure up to 4 MPa and the solid-gas ratio up to 450 kg·m-3.The influences of conveying differential pressure,gas volume flow rate and superficial velocity on the solid-gas ratio were investigated.The Shannon entropy analysis of pressure fluctuation time series was developed to reveal the flow characteristics.Through the investigation on the distribution of Shannon entropy in different conditions,the flow stability and evolutional tendency of Shannon entropy in different regimes and regime transition processes were discovered.The relationship between Shannon entropy and flow regimes was also established.The results indicated that solid gas ratio and Shannon entropy increased with increasing conveying differential pressure.Shannon entropy was different for different flow regimes,and was able to identify the flow regimes.Shannon entropy analysis is a feasible approach to researching the characteristics of flow regimes and flow regime transitions in dense-phase pneumatic conveying under high pressure.展开更多
基金Wengfu Phosphate Fertilizer Plant(WPFP),WengFu(Group) Co.,Ltd,Guizhou,China for financial supportgrants from National Science and Technology Support Program(No.2012BAA08B00)Science and Technology Integrated Innovation Project of Shaanxi Province(No.2012KTZB03-04)
文摘Ammonium sulfate residue is a particulate solid and is produced during the manufacture of ammonium sulfate fertilizer. The residue used in this study contained a large portion of calcium carbonate, from which active lime （CaO） was recovered via thermal decomposition. We used a purpose-built device to decom- pose the residue in a semi-suspension state. We found that CaO had the highest activity when residue was decomposed at 850-900 ~C. Our experiments indicated that ammonium sulfate residue should be decom- posed in a suspension state to produce active CaO. Based on our laboratory test findings, an industrial-scale production line with a high solid/gas ratio in a suspension state was devised. The optimal operating con- ditions for the decomposition of the ammonium sulfate residue to produce high quality CaO were also investigated.We found that the CaCO3 decomposition rate was high and the CaO product was highly active, averaging 170 s by the citric acid method. Morphology measurements showed that the CaO product had a porous structure and a large specific surface ensuring high activity.
文摘YTB block in Sichuan basin is a favorable area to exploit oil and gas in shallow tight rock. 3D seismic project of this zone has two characteristics. Firstly, it has high requirements for the tolerance rate of the construction process and the acquisition of high signal-to-noise ratio seismic data;Second, there are widely obstacles and noises that lead to difficult acquisition construction organization. In acquisition practice, high signal-to-noise ratio seismic data was obtained by reasonable design of construction scheme, optimization of excitation parameters, improvement of receiving conditions and optimization of obstacle crossing observation system. .
文摘The dissolution kinetics of calcined ulexite in ammonium chloride solutions at high solid-to-liquid ratios were investigated. In the experiments, calcination temperature, solution concentration, reaction temperature, and pre-hydration were chosen as parameters. It was observed that the dissolution rate increased with increasing calcination temperature, solution concentration, and reaction temperature, whereas it was not affected by pre-hydration. Employing graphical and statistic methods, the dissolution rate, based on homogeneous reaction model, can be given as: (1-X(B2O3))-1-1= k(c(NH4Cl))1.982t. The activation energy for the dissolution of the ulexite sample calcined at 160 ℃ was found to be 84.04 kJ·mol-1.
基金Supported by the Scientific Research Funds from China University of Petroleum(Beijing)(No.2462014YJRC018)partially supported by the National Natural Science Foundation of China(No.21506253 and No.91534204)
文摘In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.
基金financially supported by the National Natural Science Foundation of China,under grant numbers 51876177,51276150,and 51576165。
文摘This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion.The ablation rate of ethylene-propylene-diene monomer(EPDM)insulator was measured after the experiment.Experimental results were analyzed through scanning electron microscopy and microcomputed tomography.The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results.The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform.The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation,and the ablation characteristic region is easily formed with the exfoliation of the charred layer.The ablation rate difference of the insulator increases with gas velocity.
基金the National Key Research and Development Program of China(grant No.2022YFC2904401)Guangxi Science and Technology Major Project(grant No.GuiKe AA23023033).
文摘A full-cycle numerical simulation of a circulating fluidized bed(CFB)by the use of the computational particle fluid dynamics(CPFD)method has been developed.The effects of the presence or absence of the secondary air,different secondary air positions,and different secondary air ratios on the gas–solid flow characteristics were explored.The results show that the presence of the secondary air makes a core-annular structure of the velocity distribution of particles in the fluidized bed,which enhances the uniformity of particles’distribution and the stability of fluidization.The position and the ratio of the secondary air have a significant impact on the particle distribution,particle flow rate,and gas flow rate in the fluidized bed.When the secondary air position and ratio are optimal,the particles,particle flow rate,and air flow rate in the CFB are evenly distributed,the gas–solid flow state is good,and the CFB can operate stably.
文摘Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were carried out in an experimental test facility with the conveying pressure up to 4 MPa and the solid-gas ratio up to 450 kg·m-3.The influences of conveying differential pressure,gas volume flow rate and superficial velocity on the solid-gas ratio were investigated.The Shannon entropy analysis of pressure fluctuation time series was developed to reveal the flow characteristics.Through the investigation on the distribution of Shannon entropy in different conditions,the flow stability and evolutional tendency of Shannon entropy in different regimes and regime transition processes were discovered.The relationship between Shannon entropy and flow regimes was also established.The results indicated that solid gas ratio and Shannon entropy increased with increasing conveying differential pressure.Shannon entropy was different for different flow regimes,and was able to identify the flow regimes.Shannon entropy analysis is a feasible approach to researching the characteristics of flow regimes and flow regime transitions in dense-phase pneumatic conveying under high pressure.
