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271.
This paper deals with the application of a general predictive controller to a pulsed liquid-liquid extraction column. The control purpose is to maintain the column in its optimal behaviour zone in spite or flowrates and physical properties of solvent and solute fluctuations. The complex dynamics of the column is modeled by a low order linear discrete model with time varying parameters which are recursively identified. Based on these estimates, the control policy is adapted on line. The obtained results illustrate the successful application of such an adaptive algorithm. 相似文献
272.
273.
This paper investigates the effect of sparger geometry on flow regime of a bubble column. The experiments presented in this study were performed under atmospheric pressure with water/air in a cylindrical Plexiglas® column of 33.0 cm i.d. and 3.0 m height. Three different perforated plate spargers were employed. Hole diameter was varied in the range of 1–3 mm, while the free area was 1.0%.The theory of linear stability is used for the prediction of regime transitions in the bubble column and a comparison has been presented between the predictions and the experimental observations. A good agreement between the predictions and the experimental values of transition gas holdup has been obtained.In addition, the data from the literature has been analyzed. Experimental values of transition gas holdups and predictions by the theory of linear stability have been compared with those of literature.A correlation based on dimensionless numbers (Archimedes, Froude, Eötvös and Weber) and the group (do/DC) for the prediction of gas holdup in homogeneous regime is proposed. The average error between the correlation predictions and experimental values remains under ±10%.The proposed correlation is compared with the published data and found to be in fairly good agreement. 相似文献
274.
Characterizing the complex two-phase hydrodynamics in structured packed columns requires a power-ful modeling tool. The traditional two-dimensional model exhibits limitations when one attempts to model... 相似文献
275.
276.
针对窑炉电助熔应用不同的电源电缆布置方式,通过专用仪表对电缆电流进行测量并分析对比数据,阐述了电缆错相布置对电缆电流平衡分布的积极意义。举例分析减少电源电缆铜损的可行性,论证玻璃钢桥架和电气绝缘板等电缆支撑方式的必要性,同时对比、分析不同电缆线径和不同电缆数量在实际应用中的效果差异。 相似文献
277.
G. Prakash Narayan Mostafa H. Sharqawy Steven Lam Sarit K. Das John H. Lienhard V 《American Institute of Chemical Engineers》2013,59(5):1780-1790
Carrier gas based thermodynamic cycles are common in water desalination applications. These cycles often require condensation of water vapor out of the carrier gas stream. As the carrier gas is most likely a noncondensable gas present in very high concentrations (60–95%), a large additional resistance to heat transfer is present. It is proposed to reduce the aforementioned thermal resistance by condensing the vapor–gas mixture in a column of cold liquid rather than on a cold surface using a bubble column heat exchanger. A theoretical predictive model for estimating the heat‐transfer rates and new experimental data to validate this model are described. The model is purely physics based without the need for any adjustable parameters, and it is shown to predict heat rates within 0 to ?20% of the experimental values. The experiments demonstrate that heat‐transfer rates in the proposed device are up to an order magnitude higher than those achieved in existing state‐of‐the‐art dehumidifiers. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1780–1790, 2013 相似文献
278.
279.
《溶剂提取与离子交换》2013,31(3):307-317
Abstract The hydrodynamic and mass‐transfer performance of a 75 mm diameter pulsed disc and doughnut column (PDD) and a pulsed sieve‐plate column (PSP) are presented and compared for a toluene–acetone–water system under similar operating conditions. It was found that the pulsed disc and doughnut column flooded earlier than the pulsed sieve‐plate column, indicating that the total throughput per unit cross‐sectional area through the pulsed disc and doughnut column was less. At similar operating conditions (i.e., flowrates, pulse frequency, and amplitude), the mass‐transfer performance of the pulsed disc and doughnut column was higher, and its holdup higher. The mass‐transfer performance of the PSP column, when compared at similar holdup to the PDD, was found to be higher, and so it is concluded that it is a more efficient column for this system. 相似文献
280.
研究了鼓泡塔中臭氧在对硝基苯酚溶液中的吸收传质过程。首先探讨了pH值和气速对对硝基苯酚降解速率的影响。在 298K下,臭氧被连续通入对硝基苯酚溶液中,臭氧的传质速率因为溶解臭氧与对硝基苯酚的快速反应而大大加强。然后运用与实验条件相同的操作参数,进行了臭氧在鼓泡塔中吸收过程的模拟研究,采用MATLAB软件求解吸收过程的质量平衡方程,模拟了吸收过程中臭氧和对硝基苯酚浓度的变化,并与实验值进行了比较。结果表明,在短的鼓泡塔中,应用全混流模型来描述气相和液相的流体状态是可行的,在 80%的对硝基苯酚降解之前,模拟值和实验值能很好地一致。 相似文献