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Prediction of Flash Point Temperature of Organic Compounds Using a Hybrid Method of Group Contribution+Neural Network+Particle Swarm Optimization
Juan A. Lazzús
   2010, 18 (5): 817-823.  
Abstract3804)      PDF(pc) (219KB)(47)       Save
The flash points of organic compounds were estimated using a hybrid method that includes a simple group contribution method (GCM) implemented in an artificial neural network (ANN) with particle swarm optimization (PSO). Different topologies of a multilayer neural network were studied and the optimum architecture was determined. Property data of 350 compounds were used for training the network. To discriminate different substances the molecular structures defined by the concept of the classical group contribution method were given as input variables. The capabilities of the network were tested with 155 substances not considered in the training step. The study shows that the proposed GCM+ANN+PSO method represent an excellent alternative for the estimation of flash points of organic compounds with acceptable accuracy (AARD=1.8%;AAE=6.2 K).
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Cited: Baidu(62)
Numerical Simulation of Direct-contact Condensation from a Supersonic Steam Jet in Subcooled Water
Ajmal Shah, Imran Rafiq Chughtai, Mansoor Hameed
   2010, 18 (4): 577-587.  
Abstract5389)      PDF(pc) (477KB)(117)       Save
The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics (CFD) simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·(m2·K) -1 for water temperature in the range of 293-343 K.
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Cited: Baidu(53)
Adaptive State Feedback Predictive Control and Expert Control for a Delayed Coking Furnace
ZHANG Weiyong, HUANG Dexian, WANG Yudong, WANG Jingchun
   2008, 16 (4): 590-598.  
Abstract2542)      PDF(pc) (334KB)(1771)       Save
An adaptive state feedback predictive control (SFPC) scheme and an expert control scheme are presented and applied to the temperature control of a 1200 kt·a-1 delayed coking furnace, which is the key equipment for the delayed coking process. Adaptive SFPC is used to improve the performance of temperature control in normal operation. A simplified nonlinear model on the basis of first principles of the furnace is developed to obtain a state space model by linearization. Taking advantage of the nonlinear model, an online model adapting method is presented to accommodate the dynamic change of process characteristics because of tube coking and load changes. To compensate the large inverse response of outlet temperature resulting from the sudden increase of injected steam of a particular velocity to tubes, a monitoring method and an expert control scheme based on heat balance calculation are proposed. Industrial implementation shows the effectiveness and feasibility of the proposed control strategy.
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Cited: Baidu(52)
A Framework for the Systematic Design of Hybrid Separation Processes
Wolfgang Marquardt, Sven Kossack, Korbinian Kraemer
   2008, 16 (3): 333-342.  
Abstract3363)      PDF(pc) (328KB)(968)       Save
The design of optimal separation flow sheets for multi-component mixtures is still not a solved problem. This is especially the case when non-ideal or azeotropic mixtures or hybrid separation processes are considered. We review recent developments in this field and present a systematic framework for the design of separation flow sheets. This framework proposes a three-step approach. In the first step different flow sheets are generated. In the second step these alternative flow sheet structures are evaluated with shortcut methods. In the third step a rigorous mixed-integer nonlinear programming (MINLP) optimization of the entire flow sheet is executed to determine the best alternative. Since a number of alternative flow sheets have already been eliminated, only a few optimization runs are necessary in this final step. The whole framework thus allows the systematic generation and evaluation of separation processes and is illustrated with the case study of the separation of ethanol and water.
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Cited: Baidu(40)
Permeability and Selectivity of Sulfur Dioxide and Carbon Dioxide in Supported Ionic Liquid Membranes
JIANG Yingying, WU Youting, WANG Wenting, LI Lei, ZHOU Zheng, ZHANG Zhibing
   2009, 17 (4): 594-601.  
Abstract3054)      PDF(pc) (293KB)(45)       Save
Permeabilities and selectivities of gases such as carbon dioxide(CO2),sulfur dioxide(SO2),nitrogen(N2)and methane(CH4)in six imidazolium-based ionic liquids([emim][BF4],[bmim][BF4],[bmim][PF64],[bmim][Tf2N]and[emim][CF3SO3])supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45℃ and pressure of N22 has the highest permeability in the tested supported ionic liquid membranes,being an order of magnitude higher than that of CO2,and about 2 to 3 orders of magnitude larger than those of N2 and CH4.The observed selectivity of SO2 over the two ordinary gas components is also striking.It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes,as well as the nature of ionic liquids play important roles in the gas permeation.A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases.By considering the factors that influence the permeabilities and selectivities of CO2 and SO2,it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.
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Cited: Baidu(39)
Sorption of Acid Dyes onto Silica Modified with Cetyltrimethylammonium Cations
Tahir Imran Qureshi, Dong-Ik Song, Young-Woong Jeon, Young-Sup Lee
Abstract2117)      PDF(pc) (2352KB)(742)       Save
The sorption behavior of acid dyes onto cetyltrimethylammonium bromide (CTAB)- modified
silica as a function of pH in the aqueous medium was studied. Single- and multi-solute
sorption equilibria of orange Ⅱ(OR),phenol red (PR) and Eriochrome Black T (EBT) were
studied at pH 3, unbuffered water pH and pH 11. Sorption behavior of EBT could not be
conducted at pH 3 due to its aggregation in acidic medium. All the reaction
conditions,experimental protocols and techniques remained the same throughout the sorption
process. Sorption isotherms for single-solute system were fitted by the Langmuir model,
while Langmuir competitive model (LCM) and the ideal adsorbed solution theory (IAST)
coupled with Langmuir model (IAST/Langmuir) were used for the prediction of multisolute
competitive sorption. Sorption affinities influenced by the factors like physical
interactive forces between the molecules of CTA on silica and sorbate, structural
limitations of the dyes based on their geometrical arrangement were investigated. Sorption
affinity of OR was found to be higher than that of EBT and PR at all the pH values
investigated. Magnitude of the sorption capacities was observed to be higher in acidic
medium but lower in alkaline medium. Trends of the sorption affinities in multisolute
system were similar to those in single-solute system but magnitude of the sorption
capacities was significantly reduced due to the prevailing competition among the sorbates.
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Cited: Baidu(28)
Hydroxyapatite Coatings on Titanium Prepared by Electrodeposition in a Modified Simulated Body Fluid
ZHAO Xuhui, YANG Lingfang, ZUO Yu, XIONG Jinping
   2009, 17 (4): 667-671.  
Abstract2939)      PDF(pc) (481KB)(87)       Save
Hydroxyapatite coatings were directly prepared on anodized titanium by electro-deposition method in a modified simulated body fluid.The configuration,structure and bioactivity of the coating were investigated with scanning electron microscopy(SEM),X-ray diffraction analyzer(XRD)and Fourier transform infrared spectroscopy(FTIR)techniques.The results demonstrated that pure and homogeneous hydroxyapatite coating can be obtained without any post-treatment.The prepared coating showed good bioactivity in simulated body fluid(SBF).The time required for a fully covered dense hydroxyapatite coatings was 4 days immersion in SBF.
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Cited: Baidu(28)
HU Ying, YING Xugen, D.T.Wu, J.M.Prausnitz
Abstract1550)      PDF(pc) (2902KB)(1182)       Save
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Cited: Baidu(24)
GUO Tianmin
Abstract1676)      PDF(pc) (2319KB)(737)       Save
For further improving the representation of mixture VLE data,the local composition version of CCORequation of state has been developed and tested on 42 sets low-pressure and high-pressure as well as polarand nonpolar VLE data.The data reduction results were compared with conventional quadratic mixing ruleand activity coefficient method.The comparison with quadratic mixing rule showed that the local composition version significantly im-proved the data fitting of polar systems,especially for those highly nonideal mixtures where quadratic mixingrule failed to fit satisfactorily.The comparison with the well-known activity coefficient method——Hayden-O’Connell-Wilson model,indicated that this new version gave,in general,better fit to those low-pressure strongly polar systems,which traditionally has to be treated by activity coefficient approach.
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Cited: Baidu(22)
An agent-based service-oriented integration architecture for chemical process automation
Na Luo, Weimin Zhong, Feng Wan, Zhencheng Ye, Feng Qian
Chin.J.Chem.Eng.    2015, 23 (1): 173-180.   DOI: 10.1016/j.cjche.2014.09.047
Abstract2607)      PDF(pc) (1054KB)(32)       Save
In reality, traditional process control system built upon centralized and hierarchical structures presents a weak response to change and is easy to shut down by single failure. Aiming at these problems, a new agent-based service-oriented integration architecture was proposed for chemical process automation system. Web services were dynamically orchestrated on the internet and agent behaviors were built in them. Data analysis, model, optimization, control, fault diagnosis and so on were capsuled into different web services. Agentswere used for service compositions by negotiation. A prototype system of poly(ethylene terephthalate) process automation was used as the case study to demonstrate the validation of the integration.
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Cited: Baidu(22)
A Potential Model for Cylindrical Pores
ZHANG Xianren, WANG Wenchuan
Abstract1891)      PDF(pc) (1812KB)(795)       Save
An analytical potential for cylindrical pores has been derived by introducing a variational
method into the integration for the calculation of the interaction energy between the wall
molecules and a test molecule, all of which are represented by Lennard-Jones potential. The
model proposed gives good fito the results from the cylindrical surface model and the
pseudoatom model. To test the potential proposed rigorously, we have carried out grand
canonical ensemble Monte Carlo(GCMC) simulation of nitrogen in the MCM-41 pore at 77 K, and
compared the simulated adsorption isotherm with the experimental data reported in the
literature. The simulated isotherm from our model is in almost qualitative agreement with
experiment. Consequently, the model proposed provides an explicit and accurate description
of cylindrical pores represented by the Lennard-Jones potential. Moreover, the model can be
easily applied to a variety of cylindrical pores, ranging from cylindrical surface to
finite thickness walls, in both theoretical studies and computer simulations.
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Cited: Baidu(22)
Performance of Inner-core Supersonic Gas Separation Device with Droplet Enlargement Method
MA Qingfen, HU Dapeng, HE Gaohong, HU Shijun, LIU Wenwei, XU Qiaolian, WANG Yuxin
   2009, 17 (6): 925-933.  
Abstract3868)      PDF(pc) (383KB)(76)       Save
To improve the separation performance of a supersonic gas separation device for the treatment of gas mixture with a single heavy component,a novel structure with shorter settlement distance was constructed and a method of droplet enlargement was applied.A series of experiments were carried out in the improved separation device under various conditions,using air-ethanol vapor as the medium and micro water droplets as nucleation centers.The effects of the inlet pressure,temperature and relative humidity,the swirling intensity,and mass flow rate of water on the separation performance were investigated.The separation was improved by increasing the inlet pres-sure and relative humidity.With the decrease of swirling intensity and mass flow rate of water,the separation efficiency increased first and then decreased.The inlet temperature had a slight effect on the separation.The results showed that the separation performance was effectively improved using the proposed structure and method,and the best separation in this study was obtained with the ethanol removal rate about 55% and dew point depression 27 K.The addition of water had little pollution to the air-ethanol vapor system since the water carry-over rate was within the range of-2%-0 in most cases.
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Cited: Baidu(20)
An Investigation on the Void Fraction for upward Gas-Liquid Slug Flow in Vertical Pipe
XIA Guodong, ZHOU Fangde, HU Mingsheng
Abstract1944)      PDF(pc) (1449KB)(1207)       Save
In order to investigate the influence of the entrance effect on the spatial distribution of
phases, the experiments on gas-liquid two-phase slug flow in a vertical pipe of 0.03m ID
were carried out by using optical probes and an EKTAPRO 1000 high speed motion analyzer. It
demonstrates that the radial profile of slug flow void fraction is parabolic. Influenced by
the falling liquid film, the radial profile curve of liquid slug void fraction in the wake
region is also parabolic. Since fully turbulent velocity distribution is built up in the
developed region,the void fraction profile in this region is the saddle type. At given
superficial liquid velocity, the liquid slug void fraction increases with gas velocity. The
radial profiles of liquid slug void fraction at different axial locations are all saddle
curves, but void fraction is obviously high around the centerline in the entrance region.
The nearer the measuring station is from the entrance, the farther the peak location is
away from the wall.
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Cited: Baidu(19)
Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing
Jie XIAO, Jia LI, Cristina Piluso, Yinlun HUANG
   2008, 16 (3): 416-423.  
Abstract2390)      PDF(pc) (405KB)(1009)       Save
Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly.This step involves generating multiple thin layers of polymeric coatings on the vehicle sur-face through paint spray and curing in a multistage,dynamically changing environment.Traditionally,the quality control is solely post-process inspection based,and process operational adjustment is only experience based,thus the manufacturing may not be(highly)sustainable.In this article,a multiscale system modeling and analysis meth-odology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing.By this methodology,the correlations among paint material, application processes and coating performance can be identified.The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material,process,and product in a wide spectrum of length and time.Case studies illustrate the efficacy of the methodology for sustainable manufacturing.
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Cited: Baidu(17)
The Soret and Dufour Effects in Non-thermal Equilibrium Packed Beds with Forced Convection and Endothermic Reactions
LI Mingchun, ZHAO Zhongliang, JING Yu, LIU Jiatao, WU Yusheng
Chin.J.Chem.Eng.    2013, 21 (8): 867-875.   DOI: 10.1016/S1004-9541(13)60502-X
Abstract4066)      PDF(pc) (352KB)(541)       Save
To study the influence of the Soret and Dufour effects on the reactive characteristics of a porous packed bed with endothermic reactions and forced convection, a two-dimensional mathematical model considering the cross-diffusion effects was developed in accordance with the thermodynamics of irreversible processes and the local thermal non-equilibrium model. The simulation results were validated by comparing with experimental data. The influence of the Soret and Dufour effects on the heat transfer, mass transfer and endothermic chemical reaction in the non-thermal equilibrium packed bed is discussed. It was found that when the Peclet number reaches 1865, the maximum relative error of the concentration of gas product induced by the Soret effect is 34.7% and that of the solid fractional conversion caused by the Dufour effect is 10.8% at reaction time 160 s and initial temperature 1473 K. The differences induced by the Soret and Dufour effects are demonstrated numerically to increase gradually with the initial temperature of feeding gas and the Peclet number.
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Cited: Baidu(15)
Mechanism of Off-Bottom Suspension of Solid Particles in a Mechanical Stirred Tank
BAO Yuyun, HUANG Xiongbin, SHI Litian, WANG Yingchen
Abstract2134)      PDF(pc) (1323KB)(872)       Save
The minimum fluid velocity to maintain particles just suspended was deduced, and the
theoretical analysis shows that the minimum velocity is influenced by the properties of the
solid and liquid, not by the operational conditions. For justification, the local minimum
velocity at the bottom of the tank was measured by a bi- electrode conductivity probe, in a
square-sectioned stirred tank (0.75m×0.75m×1.0m) with the glass beads-water system.The
experiments showed that the fluid velocities for the same suspension state were identical
despite that the power dissipated per unit mass was not the same under different
configuration and operation. Both theoretical analysis and experimental results indicate
that the off-bottom suspension is controlled by the local fluid flow over the bottom of the
stirred tank.
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Cited: Baidu(14)
Extraction Behavior and Wastewater Treatment of Amino Sulfonic Acid with Alamine 336
QIN Wei, LI Zhenyu, WANG Min, DAI Youyuan
Abstract2438)      PDF(pc) (1727KB)(1140)       Save
p-Amino benzene sulfonic acid (PABSA) is selected as the solute with amphoteric functional
group,Lewis acid and Lewis base, to be separated from its dilute solutions. An aliphatic,
straight chain amine, Alamine 336, is used as the extractant, and kerosene, 1-octanol,
chloroform, butyl acetate and benzene as the diluent. The effects of pH value of solution,
extractant concentration, salt and types of diluent on the distribution coefficient, D,are
studied. There is a peak of D value with pH value of solution, the polar diluents are
favorable for extracting PABSA, and the salt in aqueous phase reduces values of D
apparently. The extraction equilibrium is described using the mass action law, and the
calculated data according to the proposed model agree with the experimental data well.
Further, the extraction behavior for other amino benzene sulfonic acids, 1-amino-8-naphtol
-3,6-disulfonic acid (H acid) and 4,4′-diaminostilbene-2,2′Cdisulfonic acid (DSD acid),
is investigated in a wide pH value region.Finally, H acid and DSD acid are successfully
removed from wastewater by the extraction with Alamine 336.
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Cited: Baidu(12)
Study on Jet Coflow Packing Tray
LAN Renshui, GAO Changbao, WANG Shuying
Abstract2438)      PDF(pc) (1011KB)(1180)       Save
Experimental study on hydrodynamics and mass transfer efficiency of jet coflow packing tray
(JCPT)was conducted in a φ285 mm column and a φ200 mm column, respectively. Compared with
new vertical sieve traywhich has been applied in the petrochemical industry since 1968, the
JCPT has lower pressure drop, higher capacityand higher mass transfer efficiency, and seems
promising in commercial application.
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Cited: Baidu(12)
Theoretical Investigation on Internal Leakage and Its Effect on the Efficiency of Fluid Switcher-Energy Recovery Device for Reverse Osmosis Desalting Plant
QI Bingwei, WANG Yue, WANG Zhaocheng, ZHANG Yanping, XU Shichang, WANG Shichang
Chin.J.Chem.Eng.    2013, 21 (11): 1216-1223.   DOI: 10.1016/S1004-9541(13)60625-4
Abstract3358)      PDF(pc) (484KB)(46)       Save
This work is focused on the theoretical investigation of internal leakage of a newly developed pilot-scale fluid switcher-energy recovery device (FS-ERD) for reverse osmosis (RO) system. For the purpose of increasing FS-ERD efficiency and reducing the operating cost of RO, it is required to control the internal leakage in a low level. In this work, the internal leakage rates at different leakage gaps and retentate brine pressures are investigated by computational fluid dynamics (CFD) method and validating experiments. It is found that the internal leakage has a linear relationship with the retentate brine pressure and a polynomial relationship with the scale of leakage gap. The results of the present work imply that low internal leakage and high retentate brine pressure bring benefits to achieve high FS-ERD efficiency.
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Cited: Baidu(12)
INVESTIGATION OF CHEMICAL AND ELECTROCHEMICAL CHANGES WITHIN CORROSION CRACKS Ⅱ.Relations between potential and pH in the bulk and occluded cell
ZUO Jingyi, ZHANG Shuxia, XU Yubao, WANG Guangyao
Abstract1684)      PDF(pc) (4215KB)(760)       Save
A simulated occluded cell which can be loaded by lever system was designed to study the changesof potential and pH in it with polarization of hulk specimen for the system "lCrl8NigTi-Cl-".It wasfound that the critical stress corrosion potential lies in the same range as the corrosion potentials ofthe occluded cell.The rule of changes of potentials and pH in the occluded cell could be classifiedinto three categories:1.When the bulk specimen is polarized above the critical potential,the occluded potentials re-main nearly constant within corrosion potential range.Meanwhile,the pH in the occluded cell decreasesrapidly from 7 to 2-3.5.The stress corrosion starts and propagates because a corrosion cell of sufficientvoltage difference is established.2.When the bulk s tyecimen is polarized below the critical potential,the occluded potential alwayskeeps a few mV more positive than the bulk potential,and the pH in the occluded cell increases to higherthan bulk pH (>7).The crevice is cathodically protected.3.When the potential of bulk specimen remained in the range of the critical potential,no changeof pH and potential in the occluded cell took place.By the above relations it would be easy to evaluate occluded potential of pH from the bulk poten-tial,and one may determine whether there is danger of crevice or stress corrosion by measuring the bulkpotential.By controlling the bulk potential one could make the initiation and propagation of crevice orstress corrosion prevented.
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Cited: Baidu(12)