The hydrodynamic characteristic of a new rotating stream tray (NRST) was investigated. The tests were carried out using an air-water/oxygen experimental system in a column with a diameter of 500 mm. The hydrodynamic p...The hydrodynamic characteristic of a new rotating stream tray (NRST) was investigated. The tests were carried out using an air-water/oxygen experimental system in a column with a diameter of 500 mm. The hydrodynamic parameters studied were dry plate pressure drop, wet plate pressure drop, weeping, entrainment, and Murphree liquid effi ciency. The results showed that the NRST has excellent performance in terms of high operational fl exibility. The pressure drop, weeping rate, and entrainment rate remained low even under a high-capacity operation. Correlations of pressure drop, weeping, and entrainment for the NRST were obtained by regression analysis. The results can provide some important theoretical guidance for the development of this type of trays.展开更多
The intention of this fundamental work is to explore the manipulation of a mixture of benzene,toluene and o-xylene separated from liquid-only transfer divided-wall column(LTS-DWC).First,two control structures are clea...The intention of this fundamental work is to explore the manipulation of a mixture of benzene,toluene and o-xylene separated from liquid-only transfer divided-wall column(LTS-DWC).First,two control structures are clearly proposed,including seven component control loops(CS1)and seven temperature control loops(CS2).However,two control structures can handle ±10% feed disturbances rather than larger feed disturbances.Subsequently,an equivalent four-column model by introducing withdraw ratio is developed to discuss the effect of two liquid-only side-stream on the overall reboiler duty.It is indicated that the second liquid-only side-stream withdraw ratio strongly affects the overall energy consumption.Hence,six-component control loops within the fixed second liquid-only side-stream withdraw ratio(CS3)is proposed and the purity of products returns to set value even as facing ±20% feed disturbances.Finally,based on the above results,it is established a temperature control structure(CS4)for controlling fixed second liquid-only side-stream withdraw ratio,which can cope with ±15% disturbances.Inspired by these findings,an insight into the dynamic control of LTS-DWC promotes the industrial implementation of DWC through new liquid-only side-stream configurations.展开更多
To adhere to the needs of automated supply of collected seedlings for mechanized grafting and cutting machines for enhancing their operational efficiency,herein,a separation system that uses subdivided air streams to ...To adhere to the needs of automated supply of collected seedlings for mechanized grafting and cutting machines for enhancing their operational efficiency,herein,a separation system that uses subdivided air streams to separate the collected seedlings is developed.The separation system comprises a feeder for supplying collected seedlings,a seedling separator that uses subdivided air streams,a picking belt for the separated seedlings,a delivery unit for the separated seedlings,a pneumatic unit,and a control unit.To investigate the complete performance of separation,picking,and delivery of the separation system,several separation experiments were conducted to separate the collected Anthurium seedlings.The results show that the consistency of the moving direction of seedlings floated by subdivided air streams in the separation container and the moving direction of the picking belt have a significant effect on the picking of the separated seedlings by the picking belt.Moreover,the seedling supply timing of the feeder has a significant effect on the stability of the collected seedling separation rate during continuous separation.When this timing is such that the percentage of separated seedlings is 70%,the separation rate of continuous separation operation is 2.24 plant/s(the separation productivity is 8060 plants/h)with 0.12 CV.The operating conditions are 0.5 MPa separation pressure,0.5 s nozzle operation time,and 60 mm seedling thickness in the separation container.Moreover,the staying times of the collected seedlings separated in the separation container are less than 2.5 min.展开更多
Three kinds of rotating-stream tray（RST）separators were designed and designated as S1,S2 and S3.The separator S1 had double flow paths,while S2 and S3 had single flow path.The trays of S1 and S2 were the same of the...Three kinds of rotating-stream tray（RST）separators were designed and designated as S1,S2 and S3.The separator S1 had double flow paths,while S2 and S3 had single flow path.The trays of S1 and S2 were the same of the double-path type,which was different from the conventional outward tray of S3.Measurements of three-dimensional flow in the three RST separators were conducted at the same total gas flow rate and streamlines were given through calculation according to the measured data.Compared with the RST separators S2 and S3,the separator S1 not only reduced the separation distance,but also effectively increased the tangential velocity,especially in the neighborhood of the separator center.The structure of tray vanes had a great effect on the velocity profiles,especially on the axial velocity profiles.The maximal axial velocities of S1 and S2 near the separator wall were much lower than that of S3.The maximal axial velocity of S1 decreased by above 37% against that of S3,which was favorable for reducing the secondary carry-over in the two-phase separation process.Streamlines showed that the separator S3 had vortex rings over the whole axial section,while the separator S1 had vortex ring only near the tray vanes.The separator outlet baffle could increase the tangential velocity,moderate the axial velocity,and reduce the centripetal velocity.展开更多
风作用于水面产生风浪,其中由于波流紊动产生的动量和能量的交换机制是一个很复杂的过程。风应力一般用来描述这种能量交换,可以分为3个部分:水面的剪切力、波生应力以及紊动应力。采用一种有效的非线性波流分离方法——NSFM(Nonlinear ...风作用于水面产生风浪,其中由于波流紊动产生的动量和能量的交换机制是一个很复杂的过程。风应力一般用来描述这种能量交换,可以分为3个部分:水面的剪切力、波生应力以及紊动应力。采用一种有效的非线性波流分离方法——NSFM(Nonlinear Stream Function Method)对波流运动的动量和能量输移进行定性描述。构造能够有效表达非线性波浪的解析流函数,摄动求解使其满足拉普拉斯方程、动力边界条件和运动边界条件,结合实验室风浪数据,分离出波生速度场。通过交叉谱分析,得到波生雷诺应力在不同风速下对风应力的贡献。结果表明:NSFM对不同工况条件下的风浪的处理具有较高的精度,模型适应性良好;且风速越大,波生应力沿着水深衰减得越快,且自由面波生应力在动量输移中的比重会逐渐减弱。展开更多
基金supported by the Shenzhen Science and Technology Research and Development Fund (JCYJ20160331113033413 and JCYJ20150630114140637)
文摘The hydrodynamic characteristic of a new rotating stream tray (NRST) was investigated. The tests were carried out using an air-water/oxygen experimental system in a column with a diameter of 500 mm. The hydrodynamic parameters studied were dry plate pressure drop, wet plate pressure drop, weeping, entrainment, and Murphree liquid effi ciency. The results showed that the NRST has excellent performance in terms of high operational fl exibility. The pressure drop, weeping rate, and entrainment rate remained low even under a high-capacity operation. Correlations of pressure drop, weeping, and entrainment for the NRST were obtained by regression analysis. The results can provide some important theoretical guidance for the development of this type of trays.
基金supported by National Natural Science Foundation of China(21908056)Shanghai Sailing Program(19YF1410800)Science and Technology Commission of Shanghai Municipality(19DZ2271100)。
文摘The intention of this fundamental work is to explore the manipulation of a mixture of benzene,toluene and o-xylene separated from liquid-only transfer divided-wall column(LTS-DWC).First,two control structures are clearly proposed,including seven component control loops(CS1)and seven temperature control loops(CS2).However,two control structures can handle ±10% feed disturbances rather than larger feed disturbances.Subsequently,an equivalent four-column model by introducing withdraw ratio is developed to discuss the effect of two liquid-only side-stream on the overall reboiler duty.It is indicated that the second liquid-only side-stream withdraw ratio strongly affects the overall energy consumption.Hence,six-component control loops within the fixed second liquid-only side-stream withdraw ratio(CS3)is proposed and the purity of products returns to set value even as facing ±20% feed disturbances.Finally,based on the above results,it is established a temperature control structure(CS4)for controlling fixed second liquid-only side-stream withdraw ratio,which can cope with ±15% disturbances.Inspired by these findings,an insight into the dynamic control of LTS-DWC promotes the industrial implementation of DWC through new liquid-only side-stream configurations.
基金This work was supported in part by the National key research and development program(Grant No.2021YFD2000700)Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams(No.2022KJ131).
文摘To adhere to the needs of automated supply of collected seedlings for mechanized grafting and cutting machines for enhancing their operational efficiency,herein,a separation system that uses subdivided air streams to separate the collected seedlings is developed.The separation system comprises a feeder for supplying collected seedlings,a seedling separator that uses subdivided air streams,a picking belt for the separated seedlings,a delivery unit for the separated seedlings,a pneumatic unit,and a control unit.To investigate the complete performance of separation,picking,and delivery of the separation system,several separation experiments were conducted to separate the collected Anthurium seedlings.The results show that the consistency of the moving direction of seedlings floated by subdivided air streams in the separation container and the moving direction of the picking belt have a significant effect on the picking of the separated seedlings by the picking belt.Moreover,the seedling supply timing of the feeder has a significant effect on the stability of the collected seedling separation rate during continuous separation.When this timing is such that the percentage of separated seedlings is 70%,the separation rate of continuous separation operation is 2.24 plant/s(the separation productivity is 8060 plants/h)with 0.12 CV.The operating conditions are 0.5 MPa separation pressure,0.5 s nozzle operation time,and 60 mm seedling thickness in the separation container.Moreover,the staying times of the collected seedlings separated in the separation container are less than 2.5 min.
文摘Three kinds of rotating-stream tray（RST）separators were designed and designated as S1,S2 and S3.The separator S1 had double flow paths,while S2 and S3 had single flow path.The trays of S1 and S2 were the same of the double-path type,which was different from the conventional outward tray of S3.Measurements of three-dimensional flow in the three RST separators were conducted at the same total gas flow rate and streamlines were given through calculation according to the measured data.Compared with the RST separators S2 and S3,the separator S1 not only reduced the separation distance,but also effectively increased the tangential velocity,especially in the neighborhood of the separator center.The structure of tray vanes had a great effect on the velocity profiles,especially on the axial velocity profiles.The maximal axial velocities of S1 and S2 near the separator wall were much lower than that of S3.The maximal axial velocity of S1 decreased by above 37% against that of S3,which was favorable for reducing the secondary carry-over in the two-phase separation process.Streamlines showed that the separator S3 had vortex rings over the whole axial section,while the separator S1 had vortex ring only near the tray vanes.The separator outlet baffle could increase the tangential velocity,moderate the axial velocity,and reduce the centripetal velocity.
文摘风作用于水面产生风浪,其中由于波流紊动产生的动量和能量的交换机制是一个很复杂的过程。风应力一般用来描述这种能量交换,可以分为3个部分:水面的剪切力、波生应力以及紊动应力。采用一种有效的非线性波流分离方法——NSFM(Nonlinear Stream Function Method)对波流运动的动量和能量输移进行定性描述。构造能够有效表达非线性波浪的解析流函数,摄动求解使其满足拉普拉斯方程、动力边界条件和运动边界条件,结合实验室风浪数据,分离出波生速度场。通过交叉谱分析,得到波生雷诺应力在不同风速下对风应力的贡献。结果表明:NSFM对不同工况条件下的风浪的处理具有较高的精度,模型适应性良好;且风速越大,波生应力沿着水深衰减得越快,且自由面波生应力在动量输移中的比重会逐渐减弱。
