The recent works on the development of computational mass transfer (CMT) method and its applications in chemical process simulation are reviewed. Some development strategies and challenges in future research are also discussed.

Microreaction technology is one of the most innovative and rapid developing fields in chemical engineering, synthesis and process technology. Many expectations toward enhanced product selectivity, yield and purity, improved safety, and access to new products and processes are directed to the microreaction technology. Microfluidic mixer is the most important component in microfluidic devices. Based on various principles, active and passive micromixers have been designed and investigated. This review is focused on the recent developments in microfluidic mixers. An overview of the flow phenomena and mixing characteristics in active and passive micromixers is presented, including the types of physical phenomena and their utilization in micromixers. Due to the simple fabrication technology and the easy implementation in a complex microfluidic system, T-micromixer is highlighted as an example to illustrate the effect of design and operating parameters on mixing efficiency and fluid flow inside microfluidic mixers.

Surfactants and builders are the two most important ingredients in laundry, household and personal-care cleaning products. They play a key role in washing processes. The development of various surfactants (e.g., anionic, nonionic, cationic, zwitterionic, and silicone surfactants) and builders (inorganic, organic and polymeric builders) used in the detergent compositions are reviewed and their detergency performance and biodegradability are discussed. In the future, the development of the surfactants and builders used in detergent compositions should be based on economic and environmental considerations. The use of the eco-friendly surfactants and builders derived from inexpensive renewable resources (e.g., alkyl polyglucosides and bio-based polyesters) in detergent compositions is the developing trends in detergent industry.

The design method of small-flow high-head centrifugal-vortex pump was presented. This pump, configured with inducer, complex-centrifugal impeller and open-vortex impeller, was put forward to deliver gas-liquid two-phase mixture. An HTB-5/60 type sample pump was developed and tested on a closed-loop test rig. Experimental studies on performance and cavitation tests for gas-liquid two-phase mixture were carried out compared with pure-water experimental results. Also the effect of gas phase on pump was analyzed and discussed. The experimental results show that performance and cavitation characteristics of the sample pump deteriorates progressively with increasing volume fraction of gas. When the total capacity Q_m is between 4.5 m³·h^-1 and 6 m³·h^-1 and the gas flow rate q_g below 0.66 m³·h^-1, or q_g/Q_m is lower than 15%, the characteristic curves are approximately parallel to those in pure water test, but the performance deteriorates sharply until an abrupt flow-cutting at a critical volume fraction of gas. This pump is found suitable for transporting gas-liquid two-phase mixture when working around rated capacity of 5 m³·h^-1 with q_g/Q_m below 15%.

An experimental study was conducted to investigate the fouling process of calcium carbonate on the heat transfer surface, during forced convective heat transfer. The dynamic monitoring apparatus of fouling resistance was set up for the present experiments. The fouling behaviors were examined under different factors including fluid velocity, hardness, alkalinity, solution temperature, and wall temperature. Asymptotic fouling curves varying with time were obtained. The fouling rate and asymptotic fouling resistance increased and the induction periods were shortened with the fluid velocity decreasing, hardness and alkalinity increasing, and solution temperature and heat transfer surface temperature increasing. The components of fouling that formed on the heat transfer surface included crystallization fouling and particulate fouling. The thermal performance parameter of fouling, ρ_fλ_f, varied from 380 to 2600 kg·W·(m⁴·K)^-1, increasing with growing velocity and decreasing solution temperature, hardness or alkalinity. Furthermore, the thermal conductivity of fouling, λ_f, varied from 1.7 to 2.2 W·(m·K)^-1.

A three-dimensional computational fluid dynamics (CFD) model for gas flow through a serrated valve tray was presented. The flow field, as well as the dry-pressure drop of the valve under the full-opening condition was simulated based on the proposed model by using FLUENT 6.0 software. Compared with the values of dry-pressure drop in different turbulent models, the simulated results using RNG k-ε model are in reasonable agreement with experimental data, indicating that RNG k-ε model is suitable in simulating gas flow through the serrated valve tray. Then the CFD model combining RNG k-ε model was used to study the three-dimensional gas flow through the considered serrated valve tray. The simulated results showed that various eddies existed on the serrated valve tray, and both the eddy and the non-eddy areas were nearly equal. The existence of addendum can decrease the eddy area caused by gas passing through the lateral outlet slots. The size of eddies can be reduced by optimizing the distance between valves.

Enhancing the chemical reaction processes by means of the energy released in the collapse of micro bubbles or cavities in the cavitation flow is a new research area. In the previous work, a new approach of measuring concentration of free hydroxyl radicals induced in cavitation flow by using methylene blue as the indicator was developed and used to study concentration of free radical induced in Venturi cavitation flow under various experimental conditions. In the present research, the radial evolution of a cavity bubble and the corresponding collapse pressure in sonic cavitation field are obtained by solving three different bubble dynamics equations[0]: Rayleigh equation, Rayleigh-Plesset equation and Gilmore equation. By comparing with the experimental data on the radial evolution of a cavity bubble in the literature, it is found that the predicted results by the Gilmore equation, which takes account of the compressibility of fluid in addition to the viscosity and interfacial tension, agree with the experimental ones better than those by other two equations. Moreover, the theoretically predicted collapse pressures are consistent with the concentration of the free hydroxyl radical induced in the experimental venture. Thus, the concentration of the liberated free hydroxyl radical not only influences the reaction rate but also is used as an available parameter for measuring collapse intensity of cavities.

A new technique for ice slurry production was explored. Multiple small water-drops were formed in another immiscible chilled liquid by a single-nozzled atomizer and frozen in the fluidized bed by direct contact heat transfer. Experiments were conducted to investigate the dynamic behaviors of the ice crystal making system. The results demonstrate that the ice crystals could be produced continuously and stably in the vertical bed with the circulating coolant of initial temperature below -5℃. The size distribution of the ice crystals appears non-uniform, but is more similar and more uniform at lower oil flow rate. The mean ice crystal size rests seriously with the jet velocity and the oil flow rate. It decreases with decreasing the oil flow rate, and reaches the maximum at an intermediate jet velocity at about 16.5 m·s^-1. The ice crystal size is also closely related to the phenomenon of drop-coalescing, which can be alleviated considerably by reducing the flow rate or lowering the temperature of the carrier oil. However, optimization of liquid-liquid atomization is a more effective approach to produce fine ice crystals of desired size.

The Reynolds stress transport model and the Eulerian two-fluid model provided by the FLUENT code were applied to evaluate the gas-particle two-phase flow in the ceramic filter vessel. The ceramic filter vessel contains six candle filters, which are arranged in the form of equilateral hexagon. The variation of the areal density of the filter cake during the filtration and the back-pulse process were analyzed. The coupling effect between filters, gas and solid, filtration and pulse cleaning process were investigated, respectively. The numerical results show a good approach to predict the particle distribution in the vessel and the particle deposition on the filter element. This study provides the base for the intensive study on the analysis of the gas-particle flow in the filter vessel.

A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles. The desalting and dewatering results of the ultrasonic-electric united process are compared with those of the electric process. For high salt-contenting crude oil (40-70 mg·L^-1), the salt content is still above 10.0 mg·L^-1 after crude oil has been treated by two-stage electric desalting process in refinery, which cannot meet the need of refinery. Ultrasonic-electric united process is a novel technology for treating the high salt-contenting oil. On the optimal operating conditions of the ultrasonic-electric united process, the salt content of crude oil can be reduced from 67.5 mg·L^-1 to 3.97 mg·L^-1 by one-stage ultrasonic-electric united process, and the water content falls below 0.3% (by volume). The results show that the ultrasonic-electric united process is more effective than the electric process in high salt-contenting oil desalting. This technology should be useful in the refinery process.

Copper incorporated MCM-48 molecular sieve adsorbents with different Cu content have been hydrothermally synthesized. The samples have been characterized by various physicochemical methods, including X-ray diffraction (XRD), nitrogen adsorption (N₂) and X-ray photoelectron spectroscopy (XPS). The results reveal that Cu-MCM-48 with mass fraction of copper up to 10% can still retain the uniform mesoporous framework of MCM-48. The copper in the framework of MCM-48 was easily auto-reduced to Cu(I) in N₂ at high temperature, which did not alter the mesoporous structure of MCM-48. The adsorption equilibrium isotherms of ethylene and ethane on these molecular sieve adsorbents have been measured at 30℃. At 100 kPa, the adsorption capacities of ethylene on 5Cu-MCM-48 and 10Cu-MCM-48 are higher than those on MCM-48. The 10Cu-MCM-48 molecular sieve adsorbent has a higher selective adsorption ratio of ethylene to ethane, the separation factor is 3.8, and the amount of ethylene adsorbed is 11.1 ml·g^-1.

The catalytic effects of single and mixed catalysts, i.e. single 3%Ca and 5%Na-BL(black liquor) catalysts and mixed 3%Ca+5%Na-BL catalyst, on carbon conversion,gasification reaction rate constant and activation energy,relative amount of harmful pollutant like sulphur containing gases have been investigated by thermogra-vimetry in steam gasification under temperature 750℃ to 950℃ at ambient pressure for three high-metamorphous anthracites (Longyan, Fenghai and Youxia coals in Fujian Province). The mixed catalyst of 3%Ca+5%Na-BL increases greatly the carbon conversion and gasification rate constant by accelerating the gasification reaction C+H₂O→CO+H₂ due to presence of alkali surface compounds [COM], [CO₂M] and exchanged calcium phenolate and calcium carboxylate (COO)₂. By adding CaCO₃ into BL catalyst in gasification, in addition to improving the catalyst function and enhancing the carbon conversion, the effective desulphurization is also achieved, but the better operating temperature should be below 900℃. The homogenous and shrinking core models can be successfully employed to correlate the relations between the conversion and the gasification time and to estimate the reaction rate constant. The reaction activation energy and pre-exponential factor are estimated and the activation energy for mixed catalyst is in a range of 98.72-166.92 kJ·mol^-1, much less than 177.50-196.46 kJ·mol^-1 for non-catalytic steam gasification for three experimental coals.

To improve the detection and identification performance of the Statistical Quality Monitoring (SQM) system, a novel quality based Prioritized Sensor-Fault Detection (PSFD) methodology is proposed. Weighted by the V_p (variable importance in projection) index, which indicates the importance of the sensor variables to the quality variables, the new monitoring statistic, Q_v, is developed to ensure that the most vital sensor faults be detected successfully. Subsequently, the ratio between the Detectable Minimum Faulty Magnitude (DMFM) of the most important sensor and of the least important sensor is only V_pmin/V_pmax<<1. The Structured Residuals are designed according to the V_p index to identify and then isolate them. The theoretical findings are fully supported by simulation studies performed on the Tennessee Eastman process.

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.

Speed of sound data for butyl acetate+benzene, or toluene, or o-xylene,or m-xylene,or p-xylene binary mixtures have been measured over the entire range of mole fraction at 308.15 K. The excess isentropic compressibilities (K_S^E) were computed from speed of sound and density data, derived from molar excess volume data. The K_S^E values were analyzed by using graph theoretical approach. The K_S^E values evaluated by graph theory compared reasonably well with their corresponding experimental values. The K_S^E data were also expressed in terms of Redlich-Kister polynomial equation to derive the coefficients and the standard deviation.

Vapor-liquid equilibrium (VLE) data for copolymer solutions are necessary for several chemical processes. However, VLE data for copolymer solutions in the published report are rare. In this study, experimental VLE data for binary systems copolymer+solvent were obtained using a gravimetricsorption apparatus. The studied systems were hexane+poly (21% acrylonitrile-co-butadiene), hexane+poly (33% acrylonitrile-co-butadiene), hex-ane+poly (51% acrylonitrile-co-butadiene), hexane+poly (23% styrene-co-butadiene), hexane+poly (45% styrene-co-butadiene), and benzene+poly (44% styrene-co-methyl methacrylate) in the range 50-70℃. The experimental data were correlated with the UNIFAC and Elbro-FV group contribution models for the activity coefficient. Two sets of functional groups had been used to represent the monomers in copolymers:literature groups and new proposed groups. The mean deviations between experimental and calculated mass fractions about 2.4% with Elbro-FV and 13.3% with Zhong were observed when the groups proposed in this study were used, and of 3.5% for Elbro-FV and 13.2% for Zhong when literature groups were used.

Complexation and interaction between silver and amino group were applied to induce an efficient immobilization of papain on silica spheres. The silver nanoparticles were deposited on the silica spheres before papain was coupled to the silica spheres. The silica spheres with silver nanoparticles were characterized by high resolution transmission electron microscopy (HR-TEM), Fournier transform infrared spectroscopy (FT-IR), and UV-Vis scanning spectrometer. FT-IR spectrum was also used to characterize the immobilized and free papain. Effect of some factors on the activities of the immobilized papain was investigated. It was observed that the coupled yield and relative activity of the papain on Ag/SiO₂ were 1.17 and 1.86 times of those on the bare SiO₂, respectively. At an optimum concentration of silver, the observed activity of the immobilized papain was 2.1 times of that on the bare silica. In addition, the maximum specific activity of papain immobilized on Ag/SiO₂ was 819.9 U·mg^-1, which is slightly lower than that of the free papain, 906.2 U·mg^-1. Stability of the immobilized papain was also examined. The results indicate that the silver nanoparticles successfully induce a fine immobilization of papain.

In ethanol fermentation of Saccharomyces cerevisiae (S. cerevisiae), glycerol is one of the main by-products. The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPS1 encoding a channel protein that mediates glycerol export and GPD2 encoding one of glycerol-3-phosphate dehydrogenase were knocked-out using one-step gene replacement. GLT1 and GLN1 that encode glutamate synthase and glutamine synthetase, respectively, were overexpressed using two-step gene replacement in fps1Δgpd2Δ mutant. The fermentation properties of ZAL69(fps1Δ::LEU2 gpd2Δ::URA3) and ZAL808 (fps1Δ::LEU2 gpd2Δ::URA3 _PPGK1-GLT1 _PPGK1-GLN1) under microaerobic conditions were investigated and compared with those of wild type(DC124). Consumption of glucose, yield of ethanol, yield of glycerol, acetic acid, and pyruvic acid were monitored. Compared with wild type, the ethanol yield of ZAL69 and ZAL808 were improved by 13.17% and 6.66%, respectively, whereas glycerol yield decreased by 37.4% and 41.7%. Meanwhile, acetic acid yield and pyruvic acid yield decreased dramatically compared to wild type. Our results indicate that FPS1 and GPD2 deletion of S. cerevisiae resulted in reduced glycerol yield and increased ethanol yield, but simultaneous over-expression of GLT1 and GLN1 in fps1Δgpd2Δ mutant did not have a higher ethanol yield than fps1Δgpd2Δ mutant.

A fluorine-containing polyacrylate copolymer emulsion was synthesized by a seed emulsion polymerization method, in which methyl methacrylate (MMA) and butyl acrylate (BA) were used as main monomers and hexafluorobutyl methacrylate (HFMA) as fluorine-containing monomer. The structure and properties were characterized by Fourier transform infrared spectrum (FT-IR), transmission electron microscopy (TEM), particle size analysis, X-ray photoelectron spectroscopy (XPS), contact angle (CA), differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. The FTIR and TEM results showed that HFMA was effectively involved in the emulsion copolymerization, and the formed emulsion particles had a core-shell structure and a narrow particle size distribution. XPS and CA analysis revealed that a gradient concentration of fluorine existed in the depth profile of fluorine-containing emulsion film which was richer in fluorine and more hydrophobic in one side. DSC and TG analysis also showed that a clear core-shell structure existed in the fluorine-containing emulsion particles, and their film showed higher thermal stability than that of fluorine-free emulsion.

The mesoporous molecular sieve (MCM)-41 using ionic liquid as template has been prepared. The typical template of ionic liquid was [C₁₆mim]X. In this article, the use of 1-alkyl-3-methylimidazolium ([C_nmim]Br, where n=12,14,16,18,20) salts as templates in the synthesis of MCM-41 is reported. The results showed that the synthesized MCM-41 had uniform pore diameter, high surface area and stable framework. The largest surface area of MCM-41 was the one prepared with [C₁₄mim]Br as template. When using [C₁₈min]Br as template, the narrowest pore distribution sample was obtained and the effect of surface tension of template solution to MCM-41 was first discussed.

Accurate solid concentration measurement plays a key role in the process industry. Measurements analyzed offline can be used to estimate process efficiencies, to identify problems in a flow, and to validate computational models. Online measurements can be used for active control. Electrical capacitance tomography (ECT) is a unique measuring technique with great potential in multiphase flow measurement. Experimental studies are carried out on a solid concentration measurement in a cyclone separator dipleg, using ECT. In this experiment eight electrodes are selected for the ECT sensor that is placed on the straight tube of the dipleg. The fluctuating characteristics according to the screw feeder and the effect of the airflow rate from the top of the cyclone are analyzed. The feasibility and reliability of the method are verified by the experimental results.

In this article, poly(2-hydroxyethylmethacrylate-co-acrylamide) hydrogels were synthesized by bulk free-radical copolymerization of 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) for soft contact lens(SCL)-based ophthalmic drug delivery system. The copolymer was characterized with FT-IR and SEM, the swelling property of the hydrogels were studied by gravimetrical method, and chloramphenicol was used as a model drug to investigate drug release profile of the hydrogels. The results showed that poly(2-hydroxyethylmethacrylate-co-acrylamide) hydrogels were transparent and useful SCL biomaterial, the water content increased as AAm content increase and pH decrease, and in the same way, hydrogel composition affected chloramphenicol release process too. Migration rate of chloramphenicol increased as the AAm content in the hydrogels increased in the first stage of diffusion process, whereas there was no significant difference thereafter.

The enrichment of chloride anion within the occluded cell (OC) for Type 304 austenitic stainless steel in low chloride concentration solution has been investigated by means of a simulated OC. The influence of the enrichment of chloride anion on stress corrosion crack (SCC) of Type 304 stainless steel has been studied. It was observed that the amount of chloride anion migration was proportional to the charge flowing through the anode. Owning to the effects of enrichment of chloride anion, low chloride concentration solution could induce SCC for Type 304 stainless steel.

Decreasing the acetic acid consumption in purified terephthalic acid (PTA) solvent system has become a hot issue with common concern. In accordance with the technical features, the electrical conductivity is in direct proportion to the acetic acid content. General regression neural network (GRNN) is used to establish the model of electrical conductivity on the basis of mechanism analysis, and then particle swarm optimization (PSO) algorithm with the improvement of inertia weight and population diversity is proposed to regulate the operating conditions. Thus, the method of decreasing the acid loss is derived and applied to PTA solvent system in a chemical plant. Cases studies show that the precision of modeling and optimization are higher. The results also provide the optimal operating conditions, which decrease the cost and improve the profit.

The performance of a rotating packed bed (RPB) with three kinds of packings was investigated using alcohol/water solution under continuous distillation conditions at atmospheric pressure. The effects of average high gravity factor (β), reflux ratio (R), and feedstock flux (F) on mass-transfer in distillation were examined separately. Experimental results indicated that the total number of theoretical units (NTU) of RPB increased with β, R, and F. Of the three kinds of packings, the wave thread packing of stainless steel (Packing Ⅲ) had the best mass transfer efficiency with the height equivalent of a theoretical plate (HETP) of approximately 7.35 mm-23.58 mm, whereas the corrugated disk packing of stainless steel (Packing I) had the worst one with the HETP of about 13.4 mm-48.07 mm. Correlations were developed to describe the mass transfer efficiency for packings. Comparing experimental data with the data calculated by correlation, the average deviate obtained for each packing was 0.72%, 1.98%, and 2.7%, respectively, implying that the accuracy of correlations developed was reasonable.