The fan-beam optical sensor is made up of many semiconductor lasers and detectors fixed around the wall alternately at a cross section of pneumatically conveying pipe. When the sensor works, a scanning light source em...The fan-beam optical sensor is made up of many semiconductor lasers and detectors fixed around the wall alternately at a cross section of pneumatically conveying pipe. When the sensor works, a scanning light source emits a 50° lamellar fan-beam through the gas-solid two phase flow, and the projection data resulting extinction effect of solid particles are detected at the same time. With the projection data, the flow rate mass can be calculated, and then the flow image can be reconstructed. In this paper, the design of the sensor including spatial arrangement of the structural parts, basic principle and measurement sensitivity distribution are introduced. The mathematical measurement model of solid mass flow rate is presented together with the testing results.展开更多
Previous studies have indicated that piping erosion greatly threatens the safe operation of various hydraulic structures. However, few mathematical models are available to perfectly describe the erosion process due to...Previous studies have indicated that piping erosion greatly threatens the safe operation of various hydraulic structures. However, few mathematical models are available to perfectly describe the erosion process due to the complexity of piping. The focus of the present work is to propose a new fluid solid coupling model to eliminate the shortcomings of existing work. A 'pseudo-liquid' assumption is suggested to simulate the particle movement in the erosion process. Then, based on the mass and momentum conservations of the moving particles and flowing water, a new two-flow model is established by using the continuity equations and motion equations. In the model, the erosion rate of soil is determined with a particle erosion law derived from tests results of STERPI. And ERGUN's empirical equation is used to determine the interaction forces between the liquid and the solid. A numerical approach is proposed to solve the model with the finite volume method and SIMPLE algorithm. The new model is validated with the tests results of STERPI. And the soil erosion principles in piping are also explored.展开更多
Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid pa...Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid particle movement as well as particle erosion characteristics of the solid-liquid two-phase flow in a choke. The corresponding erosion reduction approach by setting ribs on the inner wall of the choke was advanced. This mathematical model includes three parts： the flow field simulation of the continuous carrier fluid by an Eulerian approach, the particle interaction simulation using the discrete particle hard sphere model by a Lagrangian approach and calculation of erosion rate using semiempirical correlations. The results show that particles accumulated in a narrow region from inlet to outlet of the choke and the dominating factor affecting particle motion is the fluid drag force. As a result, the optimization of rib geometrical parameters indicates that good anti-erosion performance can be achieved by four ribs, each of them with a height （H） of 3 mm and a width （B） of 5 mm equaling the interval between ribs （L）.展开更多
Four waste materials, paper, wood, textile and kitchen garbage, in municipal solid waste were gasified separately with oxygen in a fixed bed reactor. The yields of products char. tar and gas, the composition of gas co...Four waste materials, paper, wood, textile and kitchen garbage, in municipal solid waste were gasified separately with oxygen in a fixed bed reactor. The yields of products char. tar and gas, the composition of gas components H2, CO, CO2 and CH4, and the lower heating value （LHV） were examined at temperatures between 700 and 900 ℃ and equivalence ratio （ER） between 0.14 and 0.32. Characteristics of gas evolution during gasification were inves- tigated. Results show that a higher temperature improves the formation of H2 and CO while lowers the yield of CO2 and CH4. The LHV of syngas increases with temperature and varies in the range of 6-10 MJ. m-3 reaching the maximum at 800 ℃ or above. As ER increases, both combustible gas component and LHV of syngas decrease while the yield of CO2 rises linearly. The appropriate ER for obtaining high quality gas is in the range of 0.18-0.23. Temperature and ER have significant effects on the product distribution. Higher temperature and ER are favorable for higher gas yield and lower yield of char and tar in the gasification of textile and kitchen garbage. At 800 ℃, the gas evolution may be divided into two regions. In the first region, the flow rate of gas increases and then de- creases ranidlv, while in the second reuion the flow rate decreases monotonically to lower level.展开更多
设计了一套空气-活性炭的声发射信号检测装置,结合经典声发射理论与现代信息处理技术,对气固两相流过程中固相的质量流率、粒径以及碰撞速度等因素做细致分析。对4.00,2.80,1.18,085,0.43 mm 5种不同粒径的活性炭颗粒分别在不同质量流...设计了一套空气-活性炭的声发射信号检测装置,结合经典声发射理论与现代信息处理技术,对气固两相流过程中固相的质量流率、粒径以及碰撞速度等因素做细致分析。对4.00,2.80,1.18,085,0.43 mm 5种不同粒径的活性炭颗粒分别在不同质量流率、不同碰撞速度下的声发射信号进行采样,并采用功率谱估计算法对其进行分析。实验发现碰撞速度对信号的频率影响较小,但对信号的功率强度影响较大,此外,功率谱估计的频率、面积与固相颗粒的粒径、质量流率有很好相关性,拟合出二者的相关方程并通过试验验证,得到各参数的相对误差小于5.5%。因此,采用声发射测量技术与功率谱估计相结合的方法对于气固两项流相关参数的检测是可行有效的。展开更多
基金Project (No. 04009469) supported by the Natural Science Foundationof Guangdong, China
文摘The fan-beam optical sensor is made up of many semiconductor lasers and detectors fixed around the wall alternately at a cross section of pneumatically conveying pipe. When the sensor works, a scanning light source emits a 50° lamellar fan-beam through the gas-solid two phase flow, and the projection data resulting extinction effect of solid particles are detected at the same time. With the projection data, the flow rate mass can be calculated, and then the flow image can be reconstructed. In this paper, the design of the sensor including spatial arrangement of the structural parts, basic principle and measurement sensitivity distribution are introduced. The mathematical measurement model of solid mass flow rate is presented together with the testing results.
基金Foundation item： Project（2011BAB09B01） supported by the National Science and Technology Support Program of China Project（cstc2013jcyjA30006） supported by Chongqing Science ＆ Technology Commission, China Project（K J130412） supported by Chongqing Education Commission, China
文摘Previous studies have indicated that piping erosion greatly threatens the safe operation of various hydraulic structures. However, few mathematical models are available to perfectly describe the erosion process due to the complexity of piping. The focus of the present work is to propose a new fluid solid coupling model to eliminate the shortcomings of existing work. A 'pseudo-liquid' assumption is suggested to simulate the particle movement in the erosion process. Then, based on the mass and momentum conservations of the moving particles and flowing water, a new two-flow model is established by using the continuity equations and motion equations. In the model, the erosion rate of soil is determined with a particle erosion law derived from tests results of STERPI. And ERGUN's empirical equation is used to determine the interaction forces between the liquid and the solid. A numerical approach is proposed to solve the model with the finite volume method and SIMPLE algorithm. The new model is validated with the tests results of STERPI. And the soil erosion principles in piping are also explored.
基金supported by the Fund of Innovation Research Group of National Natural Science Foundation of China (Grant NO.5052160450323001)Major Program of National Natural Science Foundation of China (Grant No.50536020)
文摘Chokes are one of the most important components of downhole flow-control equipment. The particle erosion mathematical model, which considers particle-particle interaction, was established and used to simulate solid particle movement as well as particle erosion characteristics of the solid-liquid two-phase flow in a choke. The corresponding erosion reduction approach by setting ribs on the inner wall of the choke was advanced. This mathematical model includes three parts： the flow field simulation of the continuous carrier fluid by an Eulerian approach, the particle interaction simulation using the discrete particle hard sphere model by a Lagrangian approach and calculation of erosion rate using semiempirical correlations. The results show that particles accumulated in a narrow region from inlet to outlet of the choke and the dominating factor affecting particle motion is the fluid drag force. As a result, the optimization of rib geometrical parameters indicates that good anti-erosion performance can be achieved by four ribs, each of them with a height （H） of 3 mm and a width （B） of 5 mm equaling the interval between ribs （L）.
基金Supported by the National Basic Research Program of China(2011CB201505)the National Natural Science Foundation of China(51006023)
文摘Four waste materials, paper, wood, textile and kitchen garbage, in municipal solid waste were gasified separately with oxygen in a fixed bed reactor. The yields of products char. tar and gas, the composition of gas components H2, CO, CO2 and CH4, and the lower heating value （LHV） were examined at temperatures between 700 and 900 ℃ and equivalence ratio （ER） between 0.14 and 0.32. Characteristics of gas evolution during gasification were inves- tigated. Results show that a higher temperature improves the formation of H2 and CO while lowers the yield of CO2 and CH4. The LHV of syngas increases with temperature and varies in the range of 6-10 MJ. m-3 reaching the maximum at 800 ℃ or above. As ER increases, both combustible gas component and LHV of syngas decrease while the yield of CO2 rises linearly. The appropriate ER for obtaining high quality gas is in the range of 0.18-0.23. Temperature and ER have significant effects on the product distribution. Higher temperature and ER are favorable for higher gas yield and lower yield of char and tar in the gasification of textile and kitchen garbage. At 800 ℃, the gas evolution may be divided into two regions. In the first region, the flow rate of gas increases and then de- creases ranidlv, while in the second reuion the flow rate decreases monotonically to lower level.
文摘设计了一套空气-活性炭的声发射信号检测装置,结合经典声发射理论与现代信息处理技术,对气固两相流过程中固相的质量流率、粒径以及碰撞速度等因素做细致分析。对4.00,2.80,1.18,085,0.43 mm 5种不同粒径的活性炭颗粒分别在不同质量流率、不同碰撞速度下的声发射信号进行采样,并采用功率谱估计算法对其进行分析。实验发现碰撞速度对信号的频率影响较小,但对信号的功率强度影响较大,此外,功率谱估计的频率、面积与固相颗粒的粒径、质量流率有很好相关性,拟合出二者的相关方程并通过试验验证,得到各参数的相对误差小于5.5%。因此,采用声发射测量技术与功率谱估计相结合的方法对于气固两项流相关参数的检测是可行有效的。
