共查询到20条相似文献,搜索用时 15 毫秒
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Qunsheng Li Manxia ZhangXiaofei Tang Lun LiZhigang Lei 《Chemical Engineering Research and Design》2013
Flow-guided sieve tray (FGST) has been widely used as column internal for mass and energy transfer between gas and liquid, or liquid and liquid, due to its low pressure drop, high efficiency, and high capacity. But as sieve tray, improving the operation flexibility is the urgent task which has to be resolved. Flow-guided sieve-valve tray (FGS-VT) was designed to overcome the shortcoming of FGST by putting some valves onto the FGST, which do not change the original structure before the valves are open. Comparison of the hydrodynamic and mass transfer performances of FGS-VT, FGST, and Glitsch V1 valve tray was done, using air–water–oxygen system in a 0.6 m diameter plexiglass column, and the mathematical model of dry-plate pressure drop for FGS-VT was established. The results showed that the FGS-VT has higher operation flexibility and tray efficiency than FGST and Glitsch V1 valve tray. 相似文献
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Sieve trays are widely used in fractionating devices like tray distillation towers existing in separation and purification industries. The weeping phenomenon that has a critical effect on the efficiency of tray towers was studied by a numerical model and some experiments. The experiments were carried out in a pilot scale column with the diameter of 1.22 m that includes two test trays and two chimney trays. Weeping rates and some hydraulic parameters were measured in sieve trays with the hole area of 7.04%. Furthermore, the total weeping rate and weeping rate in inlet and outlet halves of the test tray were determined. It was also used an Eulerian–Eulerian computational fluid dynamics (CFD) method for the present study. The model was able to predict the dry tray pressure drop, total pressure drop, clear liquid height, froth height, and weeping rate simultaneously. Furthermore, the obtained CFD results were in a good agreement with the experimental data in terms of pressure drop and the model properly predicted several hydraulic parameters like the liquid weeping behavior along the tray. 相似文献
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Qun Shen Li Chun Ying Song Hai Long Wu Hui Liu Yi Qiu Qian 《Korean Journal of Chemical Engineering》2008,25(6):1509-1513
With a particular focus on the distillation of highly viscous or self-polymerized mixtures, this study reports the hydrodynamic
and mass transfer performance of two flow-guided sieve trays, including their pressure drop, entrainment, weeping and tray
efficiency, obtained experimentally with an air-water/oxygen system in a Φ600 mm plexiglass column. The results show that the 8 mm hole flow-guided sieve tray tested shows better characteristics than
the 7 mm flow-guided hole tray in terms of pressure drop and mass transfer. Then we present practical industrial examples
of applications of the flow guided trays for distillation of viscous mixtures, i.e., the separation of vinyl acetate (VAC)
from a polyvinyl acetate (PVAC) polymer solution with dynamic viscosity μ=50,000 mPas, the separation of highly unsaturated
C5 mixtures by extractive distillation, and the distillation of thick, condensed and highly viscous fermentation mixtures
made from fermented mash. It is demonstrated that flow-guided sieve trays with relatively large holes are an excellent candidate
for distillation of mixtures with suspended solids, or concentrated/self-polymerized polymer solutions. 相似文献
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This study presents a new and innovative sieve tray design for a more flexible operation of separation columns in terms of possible throughput. The advantage of this new tray design is to ensure an optimal operation for varying feed flow rates and constant separation efficiencies for different load ranges. The aim of this work is to give a short introduction and an outlook to the investigation of the functionality of the designed trays. Moreover, the general design of the new trays, first results for CFD simulations of the dry pressure drop and the experimental setup are presented. 相似文献
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A 3‐D two‐fluid CFD model in the Eulerian‐Eulerian framework was developed to predict the hydrodynamics and heat and mass transfer of sieve trays. Interaction between the two phases occurs via interphase momentum and heat and mass transfer. The tray geometries are based on the large rectangular tray of Dribika and Biddulph and FRI commercial‐scale sieve tray of Yanagi and Sakata. In this work a CFD simulation is developed to give predictions of the fluid flow patterns, hydraulics, and mass transfer efficiency of distillation sieve trays including a downcomer. The main objective has been to find the extent to which CFD can be used as a design and prediction tool for real behavior, concentration and temperature distributions, and efficiencies of industrial trays. Despite the use of simple correlations for closure models, the efficiencies obtained are very close to experimental data. The results show that values of point efficiency vary with position on the tray because of variation of affecting parameters, such as velocities, temperature and concentration gradients, and interfacial area. The simulation results show that CFD can be used as a powerful tool in tray design and analysis, and can be considered as a new approach for efficiency calculations and as a new tool for testing mixing models in both phases. CFD can be used as a “virtual experiment” to simulate tray behavior under operating conditions. 相似文献
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A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified two equations formulation for closing the differential turbulent mass transfer equation with improvement by considering the vapor injected from the sieve hole to be three dimensional. The predicted concentration distributions by using proposed model were checked by experimental work conducted on a sieve tray simulator of 1.2 meters in diameter for de-sorbing the dissolved oxygen in the feed water by blowing air. The model predictions were confirmed by the ex-perimental measurement. The validation of the proposed model was further tested by comparing the simulated re-sult with the performance of an industrial scale sieve tray distillation column reported by Kunesh et al. for the strip-ping of toluene from its water solution. The predicted outlet concentration of each tray and the Murphree tray effi-ciencies under different operating conditions were in agreement with the published data. The simulated turbulent mass transfer diffusivity on each tray was within the range of the experimental result in the same sieve column re-ported by Cai et al. In addition, the prediction of the influence of sieve tray structure on the tray efficiency by using the proposed model was demonstrated. 相似文献
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网填筛板流体力学性能研究 总被引:2,自引:0,他引:2
在直径为600mm有机玻璃塔内,以水-空气系统对放置网孔填料层的筛板(称网填筛板)和普通筛板进行了流体力学性能对比实验。研究发现,在普通筛板上加一层厚度为15mm的网孔填料,可以使雾沫夹带明显减少,负荷上限提高50%~80%。同时,塔板压降和漏液有所增加。 相似文献
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Shuo Yang Jilong Zhang Jiaxing Xue Qingpeng Wu Qunsheng Li Hongkang Zhao Liqun Zhang 《中国化学工程学报》2021,39(11):59-67
Distillation is the most common separation technology utilized in the petroleum and chemistry industries. Due to the wide usage of the distillation column, even a small improvement in performance may result in significant energy cost savings. Aiming to improve the hydrodynamics and mass transfer performance, the flow-guided trapezoid spray-packing tray (FTS-PT) was designed by combining flow-guided holes and trapezoidal caps with structured packing. And the experimental measurements of the FTS-PT, including pressure drop, clear liquid height, weeping, entrainment, and tray efficiency, were conducted in a 500 mm diameter plexiglass column with the air-water-oxygen system. Moreover, the performance of the FTS-PT was compared with that of new vertical sieve tray (New VST) and F1 valve tray. The results show that FTS-PT has a significant advantage in pressure drop, entrainment, and capacity. Furthermore, the calculation model of the pressure drop was derived and used for the FTS-PT with a relative deviation of less than 5%. 相似文献
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The hydrodynamic parameters of a Nye tray were investigated by performing experiments in a tower with a diameter of 1.22 m. Air was used as the gas phase and water was used as the liquid phase. A number of parameters such as the dry pressure drop, the total pressure drop, the clear liquid height, the froth height, and the entrainment were measured. A tray stability factor was obtained using the amount of weeping, the clear liquid height, the dry pressure drop, and the Froude number. All experiments were repeated for the matching sieve tray under the same conditions. Ultimately, advantages and disadvantages were compared, and the results demonstrated that the Nye tray has a couple of advantages over the sieve tray, except that the sieve tray is slightly more stable. 相似文献
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Taleb Zarei Rahbar Rahimi Mortaza Zivdar 《Korean Journal of Chemical Engineering》2009,26(5):1213-1219
The flow pattern and hydraulics of a Mini V-Grid valve (MVG) tray is predicted by using computational fluid dynamics simulation.
A 3-D CFD model in the Eulerian framework was used. The simulation results for MVG tray are compared with that of sieve tray.
The sieve tray geometry and operating conditions are based on the Solari and Bell’s sieve tray [1]. The MVG tray differs from
that of Solari and Bell’s sieve tray solely by the difference in design of available openings for the flow of gas. The simulation
results show that the clear liquid height and the pressure drop of MVG tray are lower than that of sieve tray whereas the
liquid velocity is higher and contacts of phases are good. The simulation results of sieve tray are in agreement with the
experimental data of Solari and Bell [1]. 相似文献
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以FCC催化剂颗粒研究垂直筛板流化床内构件对气固两相流化性能的影响,考察了板孔气速、颗粒循环量和帽罩开孔比等筛板结构对流化床压降和提升量强度的影响. 结果表明,气固两相总体逆流流动条件下,帽罩内气速达4 m/s,气固高速并流喷射无气泡,两相接触好、返混小,属快速流态化. 由于没有气泡,床层压力波动小,在塔板上颗粒返混小. 垂直筛板压降随板孔气速、帽罩底隙高度增大而增大,随帽罩开孔比、板孔径增大而减小,颗粒提升量大,床层压降大. 提升量强度随板孔气速、帽罩底隙高度、颗粒循环量增加而增大,随帽罩高度与塔节高度比增大而减少,随帽罩筛孔孔径变化存在最大值. 当帽罩开孔比为1.2~2.5、板孔面积与帽罩截面积比为0.42、帽罩底隙高与板孔孔径比为0.36~0.64时帽罩流化性能较好. 相似文献
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Anand N. Vennavelli James R. Whiteley Michael R. Resetarits 《Chemical Engineering Research and Design》2014
Existing literature models for predicting the mass transfer efficiencies of binary hydrocarbon, distillation columns employing moving valve trays are evaluated. Only four models for predicting valve tray efficiencies exist in the open literature. All of these models use data from valve trays. The last theoretical model was published in 1972, 42 years ago. By comparison, sieve tray efficiency models are numerous and recent. Sieve tray models were developed from large databases. There are no valve tray equivalents to the fundamental mechanistic models available for sieve trays. Despite the differences between valve and sieve trays, many of the phenomena on sieve and valve trays are similar. Consequently, sieve tray models can be employed to provide estimates for valve trays. In this work, using public FRI data on round moving valves, the performance of the Chen and Chuang sieve tray mechanistic model is compared to the performance of four valve tray models. It appears that, in the absence of fundamental (and qualified) valve tray models, the sieve tray models present a potential alternative for valve tray efficiency predictions. 相似文献