Journal Sciences News
Zeitschrift fur Evidenz, Fortbildung und Qualitat im Gesundheitswesen
August 2018
Optimal design of an intensified column with side-reactor configuration for the methoxy-methylheptane process
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Arif Hussain, Moonyong Lee In an effort to diminish energy consumption and improve economic performance, a distillation column coupled with an adiabatic side-reactor column configuration is proposed. The production of 2-methoxy-2-methylheptane is examined to show the promising potential of process intensification using the proposed side-reactor column configuration. In order to design a side-reactor that restricts the temperature of catalyst activity to 423K, the pressure of the column and the flow rate of the feed stream withdrawn for the side-reactor are examined. An economic steady-state flowsheet is developed that minimizes the total annual cost by optimizing the column pressure, side-stream flowrate, side-stream withdrawn location, and reactor effluent reentry location. For the 2-methoxy-2-methylheptane process, the proposed side-reactor column configuration appears overwhelmingly superior in terms of capital, energy, and total annual cost compared to that of a conventional energy-intensive scheme. In addition, compared to a reactive distillation process, the proposed configuration reduces total capital investment by decreasing column diameter with a smaller catalyst load. Furthermore, additional benefits such as less expensive hardware requirement, easy catalyst removal/regeneration could be achieved. Finally, a multi-effect heat integration sequence is suggested to improve the energy and economic performance of the proposed configuration.

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August 2018
Complementary methods for the determination of the just-suspended speed and suspension state in a viscous solid–liquid mixing system
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Olivier Bertrand, Bruno Blais, Fran
August 2018
Gas holdup and liquid velocity distributions in the up flow jet-loop reactor
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Yongxiang Gao, Du Hong, Haoran Lu, Youwei Cheng, Lijun Wang, Xi Li Hydrodynamics in an up flow jet-loop reactor (JLR) is experimentally investigated. The overall gas holdup, radial and axial distributions of local gas holdup and liquid velocity are presented. A modified drift-flux model was developed for correlating the “S-shape” relationship of overall gas holdup and gas velocity. Experiments show that the gas–liquid co-injection mode results in larger gas holdup and liquid circulation velocity than those of the gas jet alone mode. Liquid velocity distribution is more prone to reach the fully developed regime than the gas holdup, and the gas–liquid co-injection promotes the flow development. Comparison of JLR with the conventional bubble column (BC) and airlift reactor (ALR) shows that the JLR has a largest liquid circulation velocity, which is mostly beneficial to liquid mixing and solid suspension.

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August 2018
CFD simulation for the effect of the header match on the flow distribution in a central-type parallel heat exchanger
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Jian Zhou, Ming Ding, Haozhi Bian, Yinxing Zhang, Zhongning Sun The present study numerically investigates the effect of the header match on the flow distribution in a central-type heat exchanger. Past studies have shown that the appropriate choice in two different header diameters (header match) will significantly help improve the flow distribution in the Z-type and U-type parallel heat exchangers. Under this circumstance, investigations are carried out on the central-type heat exchangers. According to our previous work on the effect of the geometric parameters on the flow distribution in a central-type exchanger (Zhou et al., 2017), three different types flow distribution have been pointed out. Considering the differences in characteristics among three types of the flow distribution. The investigations have been separately made on each type of flow distribution. The results indicate that for the different types of the flow distribution, the best choice of the cross-sectional area ratio of dividing header to combining header (DCR) is different. Besides, for all of three types of the flow distribution, when the DCR values less than 1, a great deal of flow maldistirbution will be brought. The present study is intended to figure out the effect of the header match on the flow distribution and provide constructive suggestions for the design of a central-type heat exchanger.
August 2018
Equal split of gas–liquid two-phase flow at variable extraction ratio
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Fachun Liang, Shitao Sun, Jifeng Gao, Luyuan Han, Guobin Shang In this work, a special distributor is proposed to distribute gas–liquid two-phase flow equally at different extraction ratio. A swirl vane is inserted at the entrance to achieve uniform swirling annular flow and ensure all the splitting holes have identical inlet conditions. A balance pipe is also applied to balance the pressure difference between the sample fluid loop and main fluid loop. Experiments were conducted in an air–water two-phase flow loop. The effect of gas and liquid superficial velocity, inlet flow pattern and splitting hole’s diameter were investigated. The results demonstrate that the extraction ratio is only dependent on the ratio of sample fluid hole number to that of main fluid. The fraction of gas and liquid taken off is not influenced by flow gas and liquid velocity, inlet flow pattern and size of the splitting hole. The desired extraction ratio can be obtained by regulating the number of sample fluid holes.

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August 2018
The interaction of confined swirling flow with a conical bluff body: Numerical simulation
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Nabil Kharoua, Lyes Khezzar, Mohamed Alshehhi Large Eddy Simulations LES were conducted to study single-phase flow in a geometry with a bluff body inserted into a long pipe as a simplified case of a more complex separator. Two configurations, without bluff body and without swirl generator, were considered for comparison. While studies on swirling flows inside pipes do exist in the literature and plenty of information is available, the present simulations address the case where the swirling flow interacts with a bluff body which was scarcely considered hitherto. The results showed a persisting core flow reversal till the bluff body location under the flow conditions considered. The swirling flow has a Rankine-vortex structure with more turbulence at its core. The bluff body undergoes the effects of recirculation zones at its front and wake regions which affect the corresponding drag and lift forces considerably. The swirl number decays from 1.5 to unity close to the bluff body. No dominant frequency was noticed in the core region. All these findings represent a starting point for an optimization work on the appropriate location and shape of the bluff body for the real separator.
August 2018
Fabrication and investigation of PEBAX/Fe-BTC, a high permeable and CO2 selective mixed matrix membrane
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Fatereh Dorosti, Asghar Alizadehdakhel Mixed matrix membranes comprising commercial poly (ether-block-amid) or PEBAX® (1657) as continues phase and Fe-BTC metal organic framework as disperse phase are fabricated via phase inversion method. To investigate membrane structure various analysis including SEM, TGA, DLS and FTIR are performed. CO2 and CH4 permeability and Selectivity are measured for all membranes at 25°C and different pressures from 3 to 25bar. Moreover, mixed gas tests are implemented for 10/90 CO2/CH4 mixture. Cross section SEM images showed proper particles distribution and good interaction between polymer and particles. The replacement of various bounds in FTIR test confirmed the good compatibility of Fe-BTC with polymer matrix too. TGA results showed acceptable thermal resistance of all membranes. Membranes permeability increased with increase in particles loading percent due to high porosity of particles and also high adsorption capacity especially for CO2 molecules. The highest CO2 permeability was belong to PEBAX/Fe-BTC 40wt.% membrane which was 425.4 Barrer. Mixed matrix membranes showed selectivity enhancement too. However, PEBAX/Fe-BTC 20wt.% membrane had the best selectivity of 22.19, in membrane with higher loading percent particles agglomeration made interfacial voids which caused selectivity decrement specially in 40wt.% loading percent. All membranes showed permeability and selectivity growth till 7bar pressures however, selectivity decreased due to plasticization effect at higher pressures of 15 and 25bar. Membrane with 25wt.% loading percent showed 50% and 9% increase in CO2 permeability and selectivity at 7bar compare to base pressure of 3bar.
August 2018
Impact of operating parameters on values of a volumetric mass transfer coefficient in a single-use bioreactor with wave-induced agitation
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Maciej Pilarek, Pawe
August 2018
Second law analysis for flow of a nanofluid containing graphene–platinum nanoparticles in a minichannel enhanced with chaotic twisted perturbations
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Mehdi Bahiraei, Nima Mazaheri The second law and entropy generation characteristics of a new hybrid nanofluid containing graphene nanoplatelets decorated with platinum nanoparticles are evaluated in a chaotic twisted channel. Although several investigations have been carried out on flows inside chaotic channels in the relevant literature, very few studies have employed nanofluids as working fluids in such configurations. The geometrical perturbations cause formation of counter rotating Dean roll-cells which intensify mixing in the flow and disturb the boundary layer. The intensity of perturbations considerably enhances at higher Dean numbers. The maximum velocity is shifted toward the outer wall due to the centrifugal force, and the maximum frictional entropy generation occurs there. Because the roll-cells lead to more uniform temperature distribution, thermal entropy generation reduces with increase of distance from the inlet of each bend. Moreover, by increasing concentration and Dean number, thermal entropy generation and Bejan number decrease while frictional entropy generation intensifies, however, due to dominance of thermal entropy generation, overall irreversibility of the nanofluid flow reduces. Besides, the temperature gradients become greater at higher wall heat fluxes which lead to the more intense thermal entropy generation. In addition, the difference between the Bejan numbers related to different wall heat fluxes is more noticeable at higher concentrations.
August 2018
Effect of shear rate on primary nucleation of para-amino benzoic acid in solution under different fluid dynamic conditions
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Valentina Nappo, Rachel Sullivan, Roger Davey, Simon Kuhn, Asterios Gavriilidis, Luca Mazzei The influence of shear rate on the primary nucleation of para-amino benzoic acid in water has been investigated via a series of cooling crystallization experiments. For each experiment, we recorded the induction time at various temperatures and supersaturation ratios, employing two flow devices: a capillary tube in which the solution was divided into hundreds of monodisperse droplets and a set of stirred vials. The capillary tube was used to perform experiments in stagnant conditions (motionless droplets) and low shear rate conditions (flowing droplets), while the stirred vials were used to perform experiments at relatively high shear rates. In this way, a wide range of shear rates was investigated. Comparing the results obtained for the motionless and flowing droplets, we saw that the nucleation rate is significantly increased (by several orders of magnitude) by the shear field; however, when the shear rate increases beyond a certain level (stirred vials experiments), we observed a drop in the nucleation rate. Thus, the results demonstrate a non-monotonic dependence of primary nucleation rate on shear rate. Various mechanisms to explain the effect of shear on nucleation are quantitatively and qualitatively discussed; however, at present no definitive conclusion can be drawn to identify the controlling mechanism.
August 2018
Critical electric field strength for partial coalescence of droplets on oil–water interface under DC electric field
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Donghai Yang, Mojtaba Ghadiri, Yongxiang Sun, Limin He, Xiaoming Luo, Yuling L
August 2018
Design and control of extractive distillation process for separation of the minimum-boiling azeotrope ethyl-acetate and ethanol
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Qingjun Zhang, Meiling Liu, Chenxiaodong Li, Aiwu Zeng Design and control of extractive distillation process is explored by taking the separation of minimum-boiling azeotrope ethyl-acetate and ethanol as an example. The two evaluation indicators of second-law efficiency and CO2 emissions are employed to evaluate different alternatives, which consist of conventional case, F-E process (hot solvent stream to preheat fresh feed of extractive column), B1-E process (hot solvent stream to preheat feed of recovery column), and F-B1-E process (hot solvent stream to preheat feed of extractive and recovery column). The conventional case can reduce 32.23% in total annual cost (TAC), 28.81% in energy-saving comparing to economically optimum fully heat-integrated pressure-swing distillation process. Besides, it can further cut 4.38% in TAC and 9.79% in steam cost by heat integration B1-E configuration while others are 1.11% (1.30%) in TAC and 10.45% (12.11%) in steam cost, where, data in the brackets are for F-B1-E process. Furthermore, the control of extractive distillation process is explored since the interaction of parameters is complicated. For conventional process, the effectiveness of single-end control strategy is determined by the method of feed composition sensitive analysis. The appropriate control scheme (CS3) is screened by the indicator of integral absolute error (IAE) since its deviations of product purities to specifications are the least. A new control scheme of bypassing portion of hot stream around economizer with dual-point temperature control strategy is proposed for the efficient economics thermal integration alternative, and it can still achieve robust control performance at facing feed flowrate and composition disturbances.

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August 2018
Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux–Dushman method applied to a stirred vessel
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Carlos Baqueiro, Nelson Ibaseta, Pierrette Guichardon, Laurent Falk This work studies how deeply the reagents choice influences micromixing characterisation by the Villermaux–Dushman method, when applying it to a 1L stainless steel standard vessel with two baffles, stirred by an inclined blade turbine. For the first time, borate and phosphate buffer are compared on their use in the method. It is observed that triiodide production is higher when borate buffer is used. Moreover, perchloric acid leads to higher triiodide production than sulphuric acid, when injecting the same concentration of both acids. Finally, the influence of the ionic strength is also studied, since there has been a great deal of controversy about it over the last years. The results show that the ionic strength affects triiodide production, although relatively slightly. Advice concerning the choice of the reagents is given in conclusion.

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August 2018
Hydrolysis kinetics of epoxypropyltrimethylammonium chloride in ethanol/water solution system
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Xiao-Fang Wan, Meng-Zhen Liu, Teng Yu, Xin-Sheng Chai, You-Ming Li, Ke Lin, Guang-Xue Chen NaOH-based hydrolysis of epoxypropyltrimethylammonium chloride (ETA) was carried out in a batch reactor using ethanol/water system. The analytic technique, headspace-gas chromatography, was employed in order to follow the time evolution of ETA aqueous solution. Various effects on hydrolysis degree, such as, molar ratio of ethanol/water, NaOH concentration, reaction temperature, and dosage of hydrolysis product (2,3-dihydroxypropyl trimethylammonium chloride) were investigated. And then the kinetic model of the hydrolysis of ETA was developed and the possible mechanism of nucleophilic ring opening reaction was proposed. Furthermore, the model parameters of the process were also determined by data fitting. The results show that ETA hydrolysis follows the pseudo-first order law and kinetic model agrees well with the experimental results. Therefore, based on this kinetic model we could control the hydrolysis degree of ETA during ETA-involved cationic etherification of natural polymer in order to improve the etherification efficiency.

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August 2018
Ehanced catalytic ozonation of NO over black-TiO2 catalyst under inadequate ozone (O3/NO molar ratio=0.6)
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Chenyang Han, Shule Zhang, Lina Guo, Yiqing Zeng, Xiaohai Li, Zhencang Shi, Yi Zhang, Baoqiang Zhang, Qin Zhong Catalytic ozonation is an attractive method for low-temperature denitrification in recent years. However, the research concerning catalytic ozonation of NO by inadequate ozone (the molar ratio of O3/NO<1) was rarely reported. In this study, black-TiO2 prepared by a sol–gel method was tested for denitrification by catalytic ozonation with O3/NO molar ratio of 0.6, presenting a 21.2% increase in NOX removal as compared to O3 alone. Interestingly, black-TiO2 also performed an 8.6% improvement in NO conversion in comparison to TiO2 catalyst. Moreover, the result of ion chromatography (IC) suggested that HNO3 was the main product of this catalytic ozonation-removal process over black-TiO2. Black-TiO2 and TiO2 were characterized by XRD, UV–vis, Raman, XPS and H2-TPR, suggesting that large numbers of Vo-OH (surface hydroxyl on oxygen vacancy) were formed on black-TiO2. UV–vis spectra of salicylic acid and p-benzoquinone revealed that a large number of additional HO2 radicals were generated in O3 +H2O+black-TiO2 system, compared with the main production of OH radicals in O3 +H2O+TiO2 system. A mechanism for catalytic ozonation denitrification over black-TiO2 was proposed. Both OH radicals and HO2 radicals were produced, especially, the Vo-OH promoted the formation of HO2 radicals, which promoted deep oxidation from NO to HNO3. Therefore, this work provides a promising approach to NOX removal with a small amount of ozone. We expect that this study can shed some lights on the catalyst design of catalytic ozonation, which contributes to the route design for denitrification.

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August 2018
Effect of ammonia on gasification performances of phenol in supercritical water
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Yuzhen Wang, Yitong Zhu, Zhuan Liu, Changqing Fang, Jianqiao Yang, Yanfeng Guo, Shuzhong Wang The solutions of phenol and the mixture of phenol and ammonia were gasified in a continuous supercritical water reactor to evaluate the influences of ammonia on the hydrogen production and the degradation pathways of phenol. The effects of temperature (560–640°C), reaction time (2–20s) and concentration of ammonia (500–2000mg/L) on gaseous distributions, gasification efficiencies and reactants removal efficiencies were investigated. In addition, the effects of ammonia on the kinds of intermediate products were analyzed. Results showed that the increasing temperature greatly promoted the hydrogen production and degradation of phenol. Longer reaction time gave a positive effect on gasification efficiencies in 10s, while the effect was little when the reaction time longer than 10s. Ammonia prevented the production of hydrogen and the degradation of phenol, which was mainly due to the generation of more stable nitrogen polycyclic compounds. The possible degradation pathways for the mixture of phenol and ammonia were proposed.
August 2018
Desulfurization of FCC gasoline by using spiral wound pervaporation module: Removal of different types of sulfur containing species
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Manish Jain, Sharad Kumar Gupta In last decade, pervaporation has been recognized as a promising novel process for desulfurization of FCC (Fluidized Catalytic Cracking) gasoline. This study deals with the comparison of the removal of different types of sulfur containing species by a spiral wound pervaporation module. For this, different binary systems containing 2-methyl thiophene, 1-butanethiol and diethyl sulfide as solute and n-heptane as solvent are selected as model gasoline. Results reported in our previous study on n-heptane/thiophene systems are also included in the analysis. Experiments were performed on a spiral wound module with PDMS/PI (Polydimethylsiloxane/Polyimide) composite membrane at a variety of operating conditions. A suitable mathematical model was then used to predict the module performance theoretically. Some of the experimental results were used to predict the membrane transport parameters for different sulfur containing compounds, and the remaining experimental results were then used to validate the mathematical model. Comparison of the model predictions and experimental results validated the mathematical model, which suggests that the reported mathematical model can be applied to design the spiral wound pervaporative modules to remove higher molecular weight thiophenes as well as other sulfur containing compounds. The presented results show that the PDMS/PI membrane is selective for all three sulfur containing compounds. However, the pervaporation process is found more suitable for removal of lower molecular weight thiophenes. Results further show that the optimum operating conditions for sulfur removal may depend on the functional groups present and molecular weight of sulfur containing compounds present in the gasoline.

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August 2018
Pervaporative desalination of high-salinity water
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Dihua Wu, Aoran Gao, Hongting Zhao, Xianshe Feng Desalination of high salinity water by pervaporation using hydrophilic poly(ether-block-amide) membranes was investigated. A flux of 1680g/(m2 h) and almost complete salt rejection (>99.9%) were achieved at 65°C. Increasing salt concentration from 1 to 20wt% resulted in a 50% reduction in water flux, whereas the salt rejection was not influenced. The salt rejection was not influenced by the salt type (i.e., NaCl, MgCl2 or Na2SO4) either. With an increase in temperature, the water flux through the membrane increased in spite of a decrease in the water permeability coefficient. The temperature dependence of water flux obeyed an Arrhenius type of relationship. Batch operation over a period of 10h showed that the water flux decline could be recovered by washing the membrane with deionized water and there was no irreversible fouling during the pervaporative desalination process.
August 2018
Model-based design of experiments in the presence of structural model uncertainty: an extended information matrix approach
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Marco Quaglio, Eric S. Fraga, Federico Galvanin The identification of a parametric model, once a suitable model structure is proposed, requires the estimation of its non-measurable parameters. Model-based design of experiment (MBDoE) methods have been proposed in the literature for maximising the collection of information whenever there is a limited amount of resources available for conducting the experiments. Conventional MBDoE methods do not take into account the structural uncertainty on the model equations and this may lead to a substantial miscalculation of the information in the experimental design stage. In this work, an extended formulation of the Fisher information matrix is proposed as a metric of information accounting for model misspecification. The properties of the extended Fisher information matrix are presented and discussed with the support of two simulated case studies.
August 2018
A quantitative analysis of drug migration during granule drying
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): Anjali Kataria, Sarang Oka, David Smr
July 2018
Fractional Monte Carlo time steps for the simulation of coagulation for parallelized flowsheet simulations
Publication date: August 2018
Source:Chemical Engineering Research and Design, Volume 136 Author(s): G. Kotalczyk, F.E. Kruis The event-driven acceptance rejection (AR) method is a computationally very advantageous Monte Carlo (MC) simulation technique for the solution of population balance equations (PBE) of coagulating systems. In the scope of the event-driven simulation approach, the simulation time is stepwise increased by a simulation time step
July 2018
Formation of alkoxy groups in the synthesis of butylated urea formaldehyde resins: Reaction mechanism and kinetic model
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Shital Amin, Nitin Padhiyar, Pratyush Dayal Water-resistant amino resins have found diverse applications in the paint and coatings industry. Butylated urea formaldehyde (BUF) amino resins exhibit excellent water-resistant properties due to the presence of butyl groups in its molecular structure. BUF resins are typically synthesized in two steps via addition and condensation reactions. Here, we develop detailed reaction mechanism for the BUF synthesis and develop the kinetic model for the addition reactions. The species in the mechanism are represented in a generic fashion and thus, our mechanism can be utilized not only for the BUF condensation reactions but also for the synthesis of other amino resins. The mechanism incorporates species containing, CH2 OCH2 linkages and the new CH2 OC4H9 end group, the presence of which have been confirmed experimentally. Further, the kinetic model for the addition reactions is developed and the values of the rate constants are determined from the isothermal experiments conducted at different temperatures. We demonstrate that the predictions from our kinetic model match the experimental observations for reaction synthesis under non-isothermal conditions. In addition, we also predict the transient behavior of intermediate species including CH2 OCH2 linkages and CH2 OC4H9 end groups, which qualitatively matches our experimental findings. The presence of these linkages opens up new possibilities to design resin-based composite materials, where functionality of oxygen can be utilized to graft nanomaterials onto the oligomers in subsequent steps. Our mechanism and the kinetic model can also be utilized for the optimization of the process conditions required for synthesis of resin with tailor-made properties.

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July 2018
Gas hold-up and mass transfer in a pilot scale bubble column with and without internals
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Onkar N. Manjrekar, Mohamed Hamed, Milorad P. Dudukovic Bubble columns are the reactors of choice for conversion of synthesis gas to liquid fuels (F–T synthesis). The F–T synthesis is an exothermic reaction and cooling internals are installed in the bubble columns to remove the heat generated in the reaction. The presence of the internals affects both the gas and liquid flow patterns in bubble column. This change is expected to reflect on the volumetric mass transfer coefficient. In this work, the impact of vertical cooling internals on overall gas hold-up and volumetric mass transfer coefficients is evaluated on 45cm diameter pilot scale bubble column and 19cm diameter lab scale bubble column. It was found that in presence of internals the gas hold-up in both the columns was increased, however no significant impact of presence of internals on volumetric mass transfer coefficient was observed. The gas hold-up and volumetric mass transfer coefficients evaluated in this work are compared with prediction from existing correlations.
July 2018
Experimental and numerical studies of residence time in SK direct contact heat exchanger for heat pump
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Hailing Fu, Lianjie Ma, Haiyan Wang Direct contact heat exchanger (DCHE) was used in energy recovery from low-grade energy resources due to their high thermal efficiency and low cost. In this work, SK elements were used in direct contact heat exchanger to enhance heat transfer due to the improving of mixing performance. It presented the residence time to characterize flow and mixing in SK direct contact heat exchanger both experimentally and numerically. The experimental results showed that the mean residence time (MRT) increased with an increase of elements numbers and it was necessary to use more elements at high flow velocity in order to guarantee the mixing completely. The residence time distribution (RTD) was used to quantify the mixing behavior and describe the mixing features such as the dead zones, channeling and by-passing. The performance of the computational fluid dynamics (CFD) was tested against the experimental data provided, verifying that the CFD model could predict the fluid flow characteristics precisely. A new shifted lognormal distribution (SLD) mathematical model was also used to model the mixing behavior of the SK direct contact heat exchanger, and there was a good fitting between model and experimental data.
July 2018
Dynamics of wet particle–wall collisions: Influence of wetting condition
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Britta Buck, Yali Tang, Niels G. Deen, J.A.M. Kuipers, Stefan Heinrich Particulate processes are characterised by intense contacts between particles and particles with the apparatus walls, where often liquid is present on the surfaces in form of droplets or liquid layers, e.g. in granulation and agglomeration processes. However, the influence of the liquid on collision dynamics is still not fully understood. Therefore, the influence of the liquid on wet particle–wall collisions is investigated via the coefficient of restitution (CoR). The CoR characterises the total energy dissipation during a collision and is defined as ratio of rebound velocity to impact velocity. In most literature regarding collision dynamics of wet particles, a target plate is covered by a liquid layer before the collision. However, this approach is often questioned of its similarity to real wet particle collisions. Therefore, during this work the particle was wetted before colliding with a dry or wet plate. Normal CoR was higher for a wet plate than for a wet particle. The case of a wet–wet collision is comparable to a superposition of collisions where a wet particle or a wet plate was used. Furthermore, during oblique collisions the tangential CoR was found to be smaller for a wet wall compared to a wet particle impacting on a dry wall.

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July 2018
Sustainable production of chemical intermediates for nylon manufacture: A techno-economic analysis for renewable production of caprolactone
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Vaishali Thaore, David Chadwick, Nilay Shah Caprolactone is a precursor for the synthesis of caprolactam, the key monomer for nylon-6 which is produced globally at a scale of 4 million tonnes per annum. This work describes and assesses a bio-based production route to caprolactone from an agricultural residue, specifically corn stover, via glucose, fructose, 5-hydroxymethyl furfural (HMF) and 1,6-hexanediol. The material and energy balances, the cost efficiency, as well as on the potential reduction of greenhouse gas (GHG) emissions are reported and discussed. The developed process model was simulated in Aspen Plus™ with the optimization and energy integration performed for the entire process from corn stover to caprolactone. A sensitivity analysis was performed with consideration of various economic factors to explore the process economics. The results of the techno-economic and environmental assessment show that a bio-based caprolactone production process via glucose and HMF could be competitive with conventional hydrocarbon-based processes when major by-products are valorised and has a lower environmental impact. Areas where further investigation is needed to improve sustainable caprolactone production are identified and discussed.
July 2018
A continuous multi-stage mixed-suspension mixed-product-removal crystallization system with fines dissolution
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): David Acevedo, Daniel J. Jarmer, Christopher L. Burcham, Christopher S. Polster, Zoltan K. Nagy This work demonstrates how crystal particle size is affected by the addition of fines dissolution in a mixed suspension mixed product removal (MSMPR) cascade system. The cooling crystallization of paracetamol in water was used as a case study. Two MSMPR cascade configurations were evaluated: (i) nucleation-growth (NG), and (ii) nucleation-dissolution-growth (NDG). Simulation results demonstrate that adding a dissolution step in the MSMPR cascade configuration increases the average product crystal size. Larger crystals and a narrower distribution were obtained due to the removal of fine crystals through the continuous process. However, a small decrease in the achievable yield was observed. Experimental results also showed a similar effect on the final mean size and CSD. The results demonstrate that a dissolution stage can be optimized to increase the final crystal size and CSD by varying the dissolution temperature to optimize the CSD with minimum effect on the achievable yield.
July 2018
Study on pyrolysis characteristics of tank oil sludge and pyrolysis char combustion
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Zhiqiang Gong, Zhentong Wang, Zhenbo Wang, Peiwen Fang, Fanzhi Meng Integrated thermal treatment of OS is a promising method for massive and effective treatment of the waste. The present work investigated the tank OS pyrolysis by a thermogravimetric analyzer and a tube furnace reactor. Pyrolysis char combustion performance was studied with the thermogravimetric analyzer. Results showed that OS pyrolysis mainly occurred between 200°C and 700°C. With the increase of pyrolysis temperature, char yield decreased while gas yield increased. When pyrolysis temperature exceeded 600°C, the oil yield decreased. Simulated distillation showed that oil products properties barely changed when pyrolysis temperature exceeded 600°C. Light fractions (gasoline and diesel) from OS pyrolysis were more than 28% higher than those of oil from OS extraction. Major components of pyrolysis gas include H2, CO, CO2, and hydrocarbons (CHS). CHS content was more than 40% in the pyrolysis gas in all cases. The molar H/C ratio and O/C ratio were lower for OS chars from higher temperature pyrolysis. The surface of OS char was rough with a well-developed pore structure formed during pyrolysis, which was conducive to the combustion reaction. The combustion characteristic of OS char from higher temperature pyrolysis was poorer than that of OS char from lower pyrolysis temperature, resulting from the less volatile content and more carbon crystal degree for OS char from higher temperature pyrolysis. With well-developed pore structure, relative simple composition, good ignition and burnout characteristics, OS char could perform well in actual combustion in CFB boilers.

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July 2018
Incorporation of silica grafted silver nanoparticles into polyvinyl chloride/polycarbonate hollow fiber membranes for pharmaceutical wastewater treatment
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): A. Behboudi, Y. Jafarzadeh, R. Yegani Polyvinyl chloride/polycarbonate hollow fiber membranes incorporated with modified silver nanoparticles were prepared by wet spinning method. Fabricated membranes were then characterized by FESEM, EDX, TGA, contact angle, pure water flux and mechanical tests. It was found that the addition of modified silver nanoparticles changed the structure of hollow fiber membranes and the size of macrovoids in the middle layer decreased whereas the thickness of sponge-like outer layer increased. The results of EDX analysis showed that the modified silver nanoparticles were dispersed uniformly throughout the membranes. In addition, degradation temperature of the membranes increased as the content of nanoparticles increased which shows that thermal resistance of membranes was improved. The number of pores on the membrane surface increased due to the presence of nanoparticles but mean pore radius decreased. Addition of modified nanoparticles also improved hydrophilicity, tensile strength and elongation of hollow fiber membranes. The membranes were finally used in a membrane bioreactor system with pharmaceutical wastewater feed during 28days and the results revealed that incorporation of modified silver nanoparticles enhanced antifouling properties of hollow fiber membranes. Moreover, pure water flux and COD removal as the criteria of membrane performance increased simultaneously.

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July 2018
Separation of azeotrope (2,2,3,3-tetrafluoro-1-propanol+water) via heterogeneous azeotropic distillation by energy-saving dividing-wall column: Process design and control strategies
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Puyun Shi, Dongmei Xu, Jinfu Ding, Jingyu Wu, Yixin Ma, Jun Gao, Yinglong Wang To separate the azeotrope of 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, the energy-saving heterogeneous azeotropic dividing-wall column (DWC) is proposed using chloroform as an azeotropic agent. Compared with the conventional design, the total condenser duty reduction of 44.57%, total reboiler duty reduction of 42.66% and TAC reduction of 37.79% by the DWC design are obtained. Based on the simulation results, the energy-saving in the DWC design is due to the thermal coupling of the conventional design and the separation of water by the decanter with the purity of 99.5mol%, rather not to the removal of remixing effect for the column sequence. The control strategy performance for the conventional and DWC designs are satisfactory, since TFP and water are separated with high purity, despite the disturbances of the flow rate of fresh feed, fresh feed composition and liquid split ratio.
July 2018
Foam propagation and oil recovery potential at large distances from an injection well
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Hamidreza Norouzi, Mehdi Madhi, Mojtaba Seyyedi, Mohmmad Rezaee While foam propagation, foam–oil interaction and foam oil recovery performance have been investigated by numerous research studies, most of previous works were performed on short porous media with the maximum length of 30cm. Therefore, their results mostly represent foam behavior in the vicinity of the injection well and may not represent the foam propagation, quality and oil recovery potential at large distances from the injection well. In this study, by using a high-pressure and high-temperature rig equipped with a 12-m long porous medium and microscopic visualization facilities, foam stability in the presence and absence of a reservoir crude oil, foam propagation, foam–oil interaction, and finally foam oil recovery potential at large distances from the injection well were investigated. The oil recovery behavior of four tertiary scenarios, including Sodium Dodecyl Sulfate (SDS) foam, Alpha-Olefin Sulfonate (AOS) foam, gas, and simultaneous water alternating gas (SWAG) injection, were investigated. According to results, pressure presented a positive impact on the foam stability. The extent of this impact was a function of the surfactant type. Compared to gas and SWAG injection, in the 12-m long porous medium, foam flooding scenarios presented much stronger oil recovery potentials. This reveals the strong potential of foam flooding in producing the oil trapped in areas deep into the reservoir and far from the injection well. Based on this study, by using a suitable surfactant solution and optimum gas fractional flow, even in the presence of oil, foam can propagate to large distances from the injection well and leads to extra oil recovery.

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July 2018
A note on short-term scheduling of multi-grade polymer plant using DNA computing
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Deepak Sharma, Manojkumar Ramteke Short-term scheduling of batch polymer plant involves the scheduling of different orders in parallel available production lines. The scheduling becomes more challenging due to the presence of sequence-dependent changeover constraints between different orders which lead to combinatorial optimization formulation. Such combinatorial optimization problems have exponential time complexity on the silicon-based computer. DNA computing experiments are found to be promising for such combinatorial optimization problems particularly involving unique feasible optimal solution. However, use of DNA to find a solution to real-life problems involving multiple feasible solutions is an emerging area of research. The present paper illustrates the DNA solutions to the short-term scheduling of a polymer plant involving multiple feasible solutions and parallel production lines. The DNA computer aided with nearest neighbour heuristics and iterative implementation found to be successfully searching the optimal solution in a combinatorial search space for three short-term scheduling problems of multi-grade polymer plant.

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July 2018
An examination of Wen and Yu’s formula for predicting the onset of fluidisation
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): I.A. Gibson, C.J. Slim, Yaoyao Zheng, S.A. Scott, J.F. Davidson, A.N. Hayhurst Classical methods (measuring the pressure drop across a bed for different flowrates of air through the bed) were used to determine the superficial velocity for minimum fluidisation, Umf , of sieved particles of alumina. The particles were characterised optically using an instrument (Morphologi G3, Malvern Instruments), which, from pixelated, enlarged photographs, measured the particles’ mean diameter, dp , to be 0.48±0.04mm and their sphericity,
July 2018
Kinetics and optimization studies using Response Surface Methodology in biodiesel production using heterogeneous catalyst
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Chandra Sekhar Latchubugata, Raghu Vamsi Kondapaneni, Kiran Kumar Patluri, Usha Virendra, Sreepriya Vedantam Biodiesel is an eco-friendly fuel is known to be an alternative source for fossil fuels. Many studies reported transesterification based reaction methods for biodiesel production from edible/non-edible oils. In this study, Calcium Oxide (CaO) has been used as a heterogeneous catalyst for transesterification of palm oil to biodiesel. Effect of process parameters such as temperature, reaction time and Methanol to oil molar ratio on biodiesel production is analyzed using Response Surface Methodology (RSM) based on Box–Behnken Design: (BBD) in statistica, with fixed catalyst concentration as an input parameter. In the present study, 3-level, 3-factor Box–Behnken statistical design was used to analyze and optimize the biodiesel production with respect to the percentage yield of Fatty Acid Methyl Esters (FAME). This has been done with 15 standard experimental runs. Kinetics of the reaction have been assumed to be of pseudo first order. Obtained biodiesel is found to be of high quality with a high FAME yield; and CaO is found to have high catalytic activity towards biodiesel production.

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July 2018
Agglomeration process of rice protein concentrate using glucomannan as binder: In-line monitoring of particle size
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Kaciane Andreola, Carlos A.M. Silva, Osvaldir P. Taranto Rice protein has raised interest from food industry due to its singular nutritional value and nutraceutical properties. However, rice protein concentrate powder presents fine particles with moderate flowability and low wettability, limiting its use. The production of large and porous granules with both high wettability and flowability can be performed by agglomeration process. In this work, the fluid bed agglomeration using konjac glucomannan as binder agent was investigated as a potential method to improve the quality attributes of the RPC powder. The influence of binder concentration and binder feed rate on particle size and quality of the product was evaluated. In-line particle size was monitored by a spatial filter velocimetry probe. Agglomeration was successfully performed in a fluid bed, resulting in large granules with low moisture content, short wetting time and improvement of the flowability. In-line particle size data allowed a better understanding of the particles growth, which was influenced by the binder concentration and binder feed rate. The best operating condition was obtained using low binder concentration and low binder feed rate, since this condition provided an instant powder with very good flowability at the highest yield.

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July 2018
Application of micro computed tomography for adjustment of model parameters for discrete element method
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Maksym Dosta, Ulrich Br
July 2018
Assessment of biomass bulk elastic response to consolidation
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): D. Ilic, K.C. Williams, D. Ellis The value and variation in bulk density is highly influential in the economics associated with biomass valorisation. Due to its importance, increased feedstock demand is directly related to understanding the characteristics affecting bulk density and the design of biomass processing and handling systems, along the renewable resource supply chains. This paper presents assessment of the elastic response of sugarcane bagasse, wheat straw and wattle, sourced from a second generation lignocellulosic ethanol plant. The study includes testing bulk solids “springiness” and the strain response to stress. While the results of this paper are a preliminary study, the ultimate aim of this work is to establish a relationship between compaction, dilation rates and magnitude with variations in the stress applied. Benchmark tests to characterise the elastic response were performed in a small cell compressibility tester. Testing was also undertaken in a larger cylinder and included preliminary evaluation using a uniaxial test apparatus. Furthermore, preliminary assessment of the stress/stain behaviour during compaction and dilation using Discrete Element Modelling (DEM) was undertaken and a comparison to experimental results is provided. Limitations of the available testing method prevented testing at higher consolidation loads and as such this work will be used to further develop the methodology and design of a new apparatus.

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Available online 15 June 2018
Impact behaviour of microparticles with microstructured surfaces: Experimental study and DEM simulation
Publication date: July 2018
Source:Chemical Engineering Research and Design, Volume 135 Author(s): Fabian Krull, Robert Hesse, Paul Breuninger, Sergiy Antonyuk The surface topography of a component influences lots of important macroscopic phenomena, for example friction, fatigue and wear behaviour. This study is focused on the effect of surface topography on the collision behaviour of fine particles. To obtain this behaviour an experimental study of the single particle impact with a microstructured substrate was performed. A novel experimental setup was developed to capture collisions of small particles with the surface three-dimensionally. The particle-wall collisions were performed with spherical polystyrene microparticles. As contact partners a polished and a microstructured stainless steel substrate were used. The surface microstructure was produced by a cold spray process with spherical stainless steel particles. The measured restitution coefficient significantly decreased after the microstructuring showing an additional energy dissipation due to topography. The particle impact was simulated using the Discrete Element Method. The surface topography was implemented in the model by reverse engineering and meshed with two different resolutions. The simulations were compared with the experiments regarding the energy dissipation and rebound behaviour. The calculated restitution coefficient was in good agreement with the experiments for a fine meshed surface, but deviated significantly with the coarsened mesh.

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Available online 15 June 2018
Comparative DEM-CFD study of binary interaction and acoustic agglomeration of aerosol microparticles at low frequencies
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Rimantas Ka
Available online 15 June 2018
A molecular collision based Lattice Boltzmann method for simulation of homogeneous and heterogeneous reactions
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Yousef Abdollahzadeh, Zahra Mansourpour, Hamed Moqtaderi, Seyed Nader Ajayebi, Mahyar Mohaghegh Montazeri A novel molecular collision based Lattice Boltzmann model at mesoscale was extended for representing hydrodynamics and concentration field of three typical reactive systems: a) a reactive flow in a catalytic pore, b) a fluid flow in a rectangular channel with a homogeneous reaction in the bulk and c) a fluid flow that passes a reactive cylindrical obstacle in a channel. For detailed comparison of the performance of the model, all problems were solved by conventional reactive Lattice Boltzmann models. Also, three Damkohler numbers including advection-based and diffusion-based were derived using dimensional analysis. For the numerical validations, the results of collision model showed a good agreement with finite element method and demonstrated the ability of the proposed model for capturing different reaction problems especially heterogeneous reactions.
Available online 15 June 2018
Inter-compartment interaction in multi-impeller mixing part I: Experiments and Multiple Reference Frame CFD
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Cees Haringa, Ruben Vandewijer, Robert F. Mudde CFD simulations of mixing in single-phase multi-Rushton stirred tanks based on the RANS methodology frequently show an over-prediction of the mixing time. This hints at an under-prediction of the mass exchange between the compartments formed around the individual impellers. Some studies recommend tuning the turbulent Schmidt number to address this issue, but this appears to be an ad-hoc correction rather than physical adjustment, thereby compromising the predictive value of the method. In this work, we study the flow profile in between two Rushton impellers in stirred tank. The data hints at the presence of macro-instabilities, and a peak in turbulent kinetic energy in the region of convergent flow, which both may promote inter-compartment mass exchange. CFD studies using the steady-state multiple reference frame model (unsteady simulations are treated in part II) inherently fail to include the macro-instability, and underestimate the turbulent kinetic energy, thereby strongly over-estimating mixing time. Furthermore, the results are highly mesh-sensitive, with increasing mesh density leading to a poorer prediction of the mixing time. Despite proper results for 1
Available online 15 June 2018
Performance analyses of LP and MILP solvers based on newly introduced scale: Case studies of water network problems in chemical processes
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Gaurav Kumar Silori, Shabina Khanam To meet fresh water requirement as well as to tackle wastewater generation are serious issues in process industries in the present scenario. To deal with water network problems, various models and computer aided tools have been used. GAMS software is used for this purpose since many years. All kind of water network models including LP, NLP, MILP and MINLP are extensively solved by this tool. However, it appears that no specific work is available in literature to observe the behaviour of different solvers on industrial case studies. The present study addresses this gap through behaviour analysis of LP and MILP solvers. Four case studies are considered from open literature, which include water networks for single contaminant, multi-contaminant and process as well as treatment units. LP models of all cases are solved through three different solvers i.e. CPLEX, CONOPT and MINOS. Further, piping cost is incorporated into LP models and thus, converted these to MILP, which are solved using three solvers such as BDMLP, CBC and SCIP. Results obtained through six solvers are compared at BECOTA scale. MINOS performs better for LP models as compared to CPLEX- a traditionally used LP solver. However, CBC is better amongst other MILP solvers considered. It is observed that selection of a particular solver may significantly influence the water network design as well as plant economy. Hence, selection of solvers should be carried out carefully.
Available online 15 June 2018
A review of catalytic partial oxidation of fossil fuels and biofuels: recent advances in catalyst development and kinetic modelling
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): P. Arku, B. Regmi, A. Dutta Synthesis gas production is a technology that dates to the 1950s. Recently, the conversion of hydrocarbons to syngas has played an important role in various applications from gas-to-liquid (GTL) processes to fuel cell applications. However, the current industrial production method is only profitable when large quantities of syngas are produced and generates high amounts of CO2 as a by-product. With the growing demands for smaller-scale and mobile syngas production technology, the catalytic partial oxidation of hydrocarbons has become a promising alternative to the conventional methane steam reforming technology. With the infrastructure for production and distribution of many commercial fuels already in place, numerous studies have been done on conversion of these fuels into syngas. This paper reviews the research that has been done in the past decade on the catalytic partial oxidation of conventional fuels and biofuels. The challenges faced in catalyst development are described as well as solutions that have been proposed to address those challenges. Advances in kinetic modelling of catalytic partial oxidation are presented, and techniques used to develop such models have also been highlighted. Finally, research gaps have been identified and recommendations have been given for further investigations to address current challenges.
Available online 15 June 2018
Effects of gas leakage on the separation performance of a cyclone. Part 2: Simulation
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Yiqun Huang, Man Zhang, Junfu Lyu, Zhi Liu, Hairui Yang This paper, second of a two-paper series, discusses the CPFD (computational particle fluid dynamics) simulation results to clarify effects of gas leakage on the separation performance of a cyclone. Compared with the experimental results in Part 1 of this two-paper series, the CPFD simulation results showed good agreements on the pressure drop, the overall separation efficiency and the grade efficiency. Gas leakage would reduce the swirling intensity in the cyclone, make the downward vortex turn upward in advance, and increase the pressure in the standpipe and the cyclone cone. The particle circulations in the cyclone might be enhanced by gas leakage.
Available online 15 June 2018
Recovery of ethanol via vapor phase by polydimethylsiloxane membrane with excellent performance
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Zhihao Si, Houchao Shan, Song Hu, Di Cai, Peiyong Qin To improve the selectivity of recovering bioethanol from fermentation broth, prevent membrane fouling by the components in fermentation, and enhance market competitiveness of bioethanol, the application of gas stripping assisted vapor permeation (GSVP) in bioethanol recovery and its potential in the integrated fermentation-separation processes were investigated in this work. As a result, a separation factor of 48, with the total flux of 866g/m2h, was obtained in separating model solution that contained 6wt % of ethanol at 65°C. In the case of recovering bioethanol from the realistic fermentation broth, GSVP process showed long-time stability, no membrane fouling and no reduction of performance. Moreover, the evaporation energy requirement for GSVP process was at least 54% and 57% less than that of the conventional distillation and pervaporation processes.
Available online 15 June 2018
Determination Of Steady-states In A Tubular Biofilm Bioreactor With Axial Dispersion
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Szymon Skoneczny, Monika Cioch The paper presents the method of modelling and numerical simulation of bioreactors with biofilm and axial dispersion of the liquid. Such bioreactors belong to systems with distributed state variables. The mathematical model was compared with a model assuming perfect mixing and a model assuming piston-flow of the liquid. According to calculations performed, the piston flow of the liquid can be assumed for Peclet numbers above 40. In turn, Peclet numbers below 0.5 justify perfect-mixing approximation. It was shown that there may exist an optimal value of Peclet number for which a maximum degree of conversion of the limiting substrate at the bioreactor outlet is obtained. The existence of the optimal Peclet number depends on the operating conditions of the bioreactor.

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Available online 15 June 2018
Natural frequency analysis of a cantilevered piping system conveying gas-liquid two-phase slug flow
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Gang Liu, Yueshe Wang Intermittent feature of slug flow could lead to variations of flow parameters varing with time and position along the pipe, which may influence dynamic behaviors of the piping system a lot. By considering significance of intermittent characteristic for two-phase slug flow, a dynamic model of a cantilevered horizontal piping system conveying gas–liquid two-phase slug flow is established to analyze natural frequency of the piping system. The functions indicated the variations of flow parameter associated with position along the pipe and time are calculated to analyze various forms of integral equations which are caused by the intermittent characteristic of slug flow to obtain the final matrix equation. The results show that intermittent feature of slug flow could have a crucial impact on natural frequency of the piping system especially when both of superficial gas velocity and pipe length are large enough. Flow parameters in gas bubble zone could play a more significant role for these cases. In addition, it is stated that in the process of predicting natural frequency by the correlation utilized in piping system conveying single-phase flow, it is pivotal to select appropriate forms of liquid holdup and liquid velocity.

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Available online 15 June 2018
Effect of Moisture Content and Length of Flexible Filamentous Particles on Cluster Characteristics in a Fluidized Bed Dryer
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Kai Wu, Linyu Gao, Zhulin Yuan, Bin Li, Wenkui Zhu, Ying Wu, Ke Zhang, Duanfeng Lu, Dengshan Luo Flexible filamentous particles have been widely applied in the industrial fluidized drying process. The hydrodynamic characteristics and equipment drying performance will be greatly influenced by the inhomogeneity of the special particle flow. So it is of great importance to gain more insight into this cluster phenomenon. In this paper, a new measurement algorithm is used to study the cluster distribution characteristics of the flexible filamentous particles in a cold fluidized riser. Specifically, influence of the particle length, moisture content and operating parameters on cluster distribution is emphasized. Moreover, the distribution of solid volume fraction inside the clusters is studied. The experimental results are compared with the clustering characteristics of spherical particles. Last, the correlation of the average cluster diameter and the frequency are formed. The results showed that the particle length, moisture content and operating condition has a significance influence on the fluidization behavior and the distribution characteristics of clusters. This work would provide an important reference for the drying process of this particular particle. All these will benefit the design and scale-up of related equipment.

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Available online 13 June 2018
Selective laser sintering of ceramic powders with bimodal particle size distribution
Publication date: Available online 15 June 2018
Source:Chemical Engineering Research and Design Author(s): Daniele Sofia, Roberto Chirone, Paola Lettieri, Diego Barletta, Massimo Poletto This paper addresses the possibility of carrying out Selective laser sintering (SLS) using powders obtained as mixtures of particles of different size. The beam source used in the experiments was a CO2 laser tube with a nominal power of 40W. The materials used were model Glass beads and a real ceramic material characterized by irregular shape of the particles. Bimodal distributed powders were generated by mixing samples characterized by different narrow particle size distributions. Single layer sintered specimens were obtained with a laser scanning speed of 50mm/s and 8W beam. The sintered specimens were studied by means of microphotography and were characterized in terms of bulk density and tensile strength.Results show that the strength of the sintered specimen is significantly dependent upon the amount of fines in the powder mixture, in spite of the limited effects on the specimen thickness and density. In particular, the highest strength of the sintered material are observed with the highest fraction of fines in the originating powder mixture. In order to estimate the value of the forces between particles of different size produced by the sintering action, the model developed by Liu et al. (2017), based on the Rumpf (1958) approach, was purposely adapted. The application of the model revealed that in our process conditions the connection between large and fines particles is significantly weaker than the force between particles of the same size. The model also indicates that the strength of the sintered materials from mixtures can potentially increase up to values significantly higher than those of the materials sintered starting from the unimodal powder components.

Inter-compartment interaction in multi-impeller mixing part II: Experiments, Sliding mesh and Large Eddy Simulations
Publication date: Available online 13 June 2018
Source:Chemical Engineering Research and Design Author(s): Cees Haringa, Ruben Vandewijer, Robert F. Mudde Steady state multiple reference frame-RANS (MRF-RANS) simulations frequently show strong over-predictions of the mixing time in single-phase, multi-impeller mixing tanks, which is sometimes patched by ad-hoc tuning of the turbulent Schmidt-number. In part I of this work, we experimentally revealed the presence of macro-instabilities in the region between the impellers, as well as a peak in the turbulent kinetic energy in the region where the flow from the individual impellers converges. The MRF-RANS method was found unable to capture both. In this second paper, we show that the sliding-mesh RANS (SM-RANS) approach does capture the effect of macro-instabilities, while still underestimating the turbulent kinetic energy. Consequently, the SM-RANS method mildly over-estimates the mixing time, while being less sensitive to the exact mesh geometry. Large eddy simulations with the dynamic Smagorinsky model reasonably capture the kinetic energy contained in macro-instabilities, and properly assess the turbulent kinetic energy in the region between the impellers, even for crude meshes. Consequently, the mixing time is reasonably assessed, and even under-predicted at the crudest meshes. However, the turbulent kinetic energy and energy dissipation in the impeller discharge stream are poorly assessed by the dynamic Smagorinsky model.
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