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Table of Content
28 January 2019, Volume 27 Issue 1
    Fluid Dynamics and Transport Phenomena
    Experimental investigation on flow characteristics in circular tube inserted with rotor-assembled strand using PIV
    Lichen He, Weimin Yang, Changfeng Guan, Hua Yan, Lin Zheng, Xiahua Zuo
    2019, 27(1):  1-9.  doi:10.1016/j.cjche.2018.03.015
    Abstract ( 529 )   PDF (12011KB) ( 32 )  
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    Rotor-assembled strand works as a typical tube insert to achieve heat transfer augmentation and scale inhibition in a heat exchanger. In this work, the PIV experiment regarding the flow fields in a circular tube inserted with rotor-assembled strand was conducted and the flow characteristics on transverse section and longitudinal section were analyzed. The results showed that swirling flow was produced in the tube inserted with rotors and it was particularly strong within the swing diameter of the rotor on the section that contains the rotor; the average turbulence intensity and the radial velocity were improved notably; the velocity vectors on the longitudinal section remained along the direction of a straight line; both the swirling flow and average turbulence intensity were higher for the rotor with three blades than for the rotor with two blades except that the radial velocity was approximate, but they were all reduced by enlarging the lead of the rotor. Characterization of the flow patterns in a circular tube contributes to understanding the heat transfer efficiency and scale inhibition performance of the rotor-assembled strand and provides guidance for its application.
    PIV experiment and large eddy simulation of turbulence characteristics in a confined impinging jet reactor
    Miao Liu, Zhengming Gao, Yongjiu Yu, Zhipeng Li, Jing Han, Ziqi Cai, Xiongbing Huang
    2019, 27(1):  10-20.  doi:10.1016/j.cjche.2018.04.006
    Abstract ( 430 )   PDF (5924KB) ( 95 )  
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    Confined impinging jet reactor (CIJR) is a typical process intensification device used in the chemical industry. In this study, two dimensional Particle Image Velocimetry (PIV) and Large Eddy Simulation (LES) method were used to investigate the flow field in a CIJR with jets of diameter 3 mm under highly turbulent condition. The results showed LES can predict the velocity and Turbulence Kinetic Energy (TKE) distributions in the reactor well by comparing with the PIV results. In the CIJR, the stagnation point fluctuates with the turbulence, and its instantaneous position accords with the normal distribution. Three methods, including s-t representation, Lumley-Newman triangle and A-G representation, were used to compare the turbulence anisotropy in the mixing chamber. It was found that the anisotropy in the impinging area and at the edge of impinging jet was strong and the maximum deviation was up to 40%. The results from 2D PIV would lead to an overestimation of the turbulent kinetic energy as much as 20% to 30% than the results from the three dimensional numerical simulation.
    CFD predictions for hazardous area classification
    Andrey Oliveira de Souza, Aurélio Moreira Luiz, Antônio Tavernard Pereira Neto, Antônio Carlos Brandao de Araujo, Heleno Bispo da Silva, Sidinei Kebler da Silva, Jose Jailson Nicacio Alves
    2019, 27(1):  21-31.  doi:10.1016/j.cjche.2018.06.002
    Abstract ( 594 )   PDF (8122KB) ( 42 )  
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    This study aimed to describe a Computational Fluid Dynamics (CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases. The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions. The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to 2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0℃ to 400℃. It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions. In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter. It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions. The deviation from the ideal gas behavior in the reservoir, achieved by applying the Soave-Redlich-Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere. The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir. The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.
    Hydrate agglomeration modeling and pipeline hydrate slurry flow behavior simulation
    Guangchun Song, Yuxing Li, Wuchang Wang, Kai Jiang, Zhengzhuo Shi, Shupeng Yao
    2019, 27(1):  32-43.  doi:10.1016/j.cjche.2018.04.004
    Abstract ( 565 )   PDF (2234KB) ( 73 )  
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    Dynamic modeling and numerical simulation of hydrate slurry flow behavior are of great importance to offshore hydrate management. For this purpose, a dynamic model of hydrate agglomeration was proposed in this paper. Based on population balance equation, the frame of the dynamic model was established first, which took both hydrate agglomeration and hydrate breakage into consideration. Then, the calculating methods of four key parameters involved in the dynamic model were given according to hydrate agglomeration dynamics. The four key parameters are collision frequency, agglomeration efficiency, breakage frequency and the size distribution of sub particles resulting from particle breakage. After the whole dynamic model was built, it was combined with several traditional solid-liquid flow models and then together solved by the CFD software FLUENT 14.5. Finally, using this method, the influences of flow rate and hydrate volume fraction on hydrate particle size distribution, hydrate volume concentration distribution and pipeline pressure drop were simulated and analyzed.
    Improving the performance of a thermoelectric power system using a flat-plate heat pipe
    Suchen Wu, Yiwen Ding, Chengbin Zhang, Dehao Xu
    2019, 27(1):  44-53.  doi:10.1016/j.cjche.2018.03.019
    Abstract ( 427 )   PDF (3555KB) ( 48 )  
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    A gravitational flat-plate heat pipe is designed and fabricated in this paper to serve as a heat spreader to diffuse the local heat source to the hot side of the thermoelectric power module. Based on this, an experimental test for the thermoelectric power generation system is conducted to study the influences of the heat spreader on the temperature uniformity and power generation performance when exposing to a local heat source. In addition, the effects of the heating power, inclination angle, and local heat source size on the power generation performance of the thermoelectric power module using a flat-plate heat pipe as a heat spreader are examined and compared with that using a metal plate. The results indicate that the gravitational flat-plate heat pipe has considerable advantages over the metal plate in the temperature uniformity. The superiority of temperature uniformity in the improvement of power generation performance for the thermoelectric power system using a heat pipe is demonstrated. Particularly, the heat pipe shows good adaptability to placement mode and the local heat source size, which is beneficial to the application in the thermoelectric power generation.
    Extending the EMMS/bubbling model to fluidization of binary particle mixture: Formulation and steady-state validation
    Nouman Ahmad, Yujie Tian, Bona Lu, Kun Hong, Haifeng Wang, Wei Wang
    2019, 27(1):  54-62.  doi:10.1016/j.cjche.2018.04.011
    Abstract ( 416 )   PDF (5172KB) ( 53 )  
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    The EMMS/bubbling model originally proposed for fluidization of monodisperse particles is extended to fluidization of binary particle mixture in this study. The dense and dilute phases are considered to comprise of two types of particles differing in size and/or density. Governing equations and the stability condition are then formulated and solved by using an optimization numerical scheme. The effects of bubble diameter are first investigated and a suitable bubble diameter correlation is chosen. Preliminary validation for steady state behavior shows the extended model can fairly capture the overall hydrodynamic behaviors in terms of volume fraction of bubbles and average bed voidage for both monodisperse and binary particle systems. This encourages us to integrate this model with CFD for more validations in the future.
    Numerical simulation of flow focusing pattern and morphological changes in two-phase flow inside nozzle
    Jin Zhao, Zhi Ning, Ming Lü, Geng Wang
    2019, 27(1):  63-71.  doi:10.1016/j.cjche.2018.08.022
    Abstract ( 394 )   PDF (2077KB) ( 42 )  
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    The flow focusing nozzle is a new type of nozzle that performs effective atomization of the discrete phase by means of high-speed motion of the continuous phase. The flow pattern and its morphological changes have a significant effect on the atomization, but the influence of different parameters on the morphological change of the flow pattern remains unclear. The flow focusing pattern and morphological changes in the two-phase flow inside the nozzle were simulated numerically, based on the volume of fluid method. The results demonstrate that the ratio of the nozzle-to-capillary distance and capillary diameter, the gas-liquid velocity ratio, and capillary diameter have significant effects on the flow pattern. When the ratio of the nozzle-to-capillary distance H and capillary diameter D increases, or the capillary diameter D increases, the flow pattern tends to transform into a laminar form; however, when the gas-liquid velocity ratio V increases, the flow pattern tends to transform into a turbulence form. Furthermore, we define the cone-shaped expansion rate, cone-shaped focusing rate, and cone angle in order to study the morphological changes in the cone shape inside the nozzle. The results indicate that the morphological change of the cone shape and flow pattern transformation is interrelated. When the cone shape tends to be unstable, the flow pattern changes towards flow blurring, whereas, a stable cone indicates that the flow tends to exhibit a droplet pattern.
    The effect of multi-orifice plate configuration on bubble detachment volume
    Jiming Wen, Qiunan Sun, Zhongning Sun, Haifeng Gu
    2019, 27(1):  72-84.  doi:10.1016/j.cjche.2018.09.024
    Abstract ( 514 )   PDF (2226KB) ( 112 )  
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    The multi-orifice plate gas sparger, mainly composed of a multi-orifice plate and a gas chamber, is one of the most common sparger facilities. The aeration performance of multi-orifice plate has a close relation with the multiorifice plate configuration. In addition, the weeping phenomenon has a considerable influence on the gas chamber condition which affects the bubble detachment volume directly. This paper conducts a set of visual experiments to study the influence of multi-orifice configuration and gas chamber condition on the aeration performance of gas sparger. For multi-orifice plate, an improved theoretical model is proposed which considers the wave effect of the previous bubbles generated from adjacent orifices and the variance of the number of active bubbling orifice. A parameter is proposed to evaluate the aeration performance in order to overcome the difficulty caused by the randomness of bubble formation process. The experimental results suggest that the gas chamber filled with water is in favor of large bubble formation. The influence of the pitch of orifice on aeration performance can only be observed in high-restricted case. According to the theoretical model and experimental results, the influences of gas flow rate and the number of open orifices on the aeration performance are analyzed and a design criterion for the number of open orifice is proposed.
    Separation Science and Engineering
    The removal of Cr(VI) through polymeric supported liquid membrane by using calix[4]arene as a carrier
    Canan Onac, Ahmet Kaya, Duygu Ataman, Nefise Ayhan Gunduz, H. Korkmaz Alpoguz
    2019, 27(1):  85-91.  doi:10.1016/j.cjche.2018.01.029
    Abstract ( 447 )   PDF (2835KB) ( 52 )  
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    In this work, the transport and removal of Cr(VI) were achieved through supported liquid membrane (SLM) by using a 5,17, di-tert-butyl-11,23-bis[(1,4-dioxa-8-azaspiro[4,5]decanyl)methyl]-25,26,27,28-tetrahydroxy calix[4]arene carrier, dissolved in 2-nitrophenyl octyl ether dichloromethane. The studied parameters are the solvent effect in the membrane phase, the effect of carrier concentration, and the acid type in the donor phase. The Celgard 2500 was used as a membrane support. We used the Danesi mass transfer model to calculate the permeability coefficients for each studied parameter. In addition, AFM and SEM techniques were used to characterize the surface morphology of the prepared Celgard 2500 membrane that included the calix[4]arene carrier.
    Analysis of equilibrium, kinetic, and thermodynamic parameters for biosorption of fluoride from water onto coconut (Cocos nucifera Linn.) root developed adsorbent
    Aju Mathew George, Ajay R. Tembhurkar
    2019, 27(1):  92-99.  doi:10.1016/j.cjche.2018.03.004
    Abstract ( 485 )   PDF (2549KB) ( 59 )  
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    Drinking water with higher fluoride levels results in serious irremediable health problems that have attained a startle all over the world. Researches focused towards deflouridation through the application of biosorbents prepared from various plants are finding greater scope and significance. Present research is done on Cocos nucifera Linn. (coconut tree) one of the very commonly available plants throughout Kerala and around the globe. An adsorbent developed from the root portion of C. nucifera Linn. is used in the present study. Equilibrium study revealed that the fluoride uptake capacity is quite significant and linearly increases with initial adsorbate concentration. The adsorption data is analyzed for Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models at varying initial adsorbate concentrations (2-25 mg·L-1). It is found that the adsorption of fluoride onto C. nucifera Linn. root adsorbent follows Langmuir isotherm. Langmuir isotherm constants "a" and "b" obtained are 2.037 mg·g-1 and 0.823 L·mg-1 at an adsorbent dose of 8 g·L-1 and temperature (26±1)℃. The mean free sorption energy, E obtained, is 9.13 kJ·mol-1 which points out that the adsorption of fluoride onto C. nucifera Linn. root adsorbent is by chemisorption mechanism. The kinetic study also supports chemisorption with adsorption data fitting well with a pseudo-second-order kinetic model with an estimated rate constant K2 of 0.2935 g·mg-1 min at an equilibrium contact time of 90 min. The thermodynamic study indicated the spontaneous and endothermic nature (ΔH=12.728 kJ·mol-1) of fluoride adsorption onto the C. nucifera Linn. root adsorbent. Scanning Electron Microscopy (SEM), BET, FTIR, and EDX methods were used to analyze the surface morphology of adsorbent before and after fluoride adsorption process. Experiments on deflouridation using C. nucifera Linn. root adsorbent application on fluoride contaminated ground water samples from fields showed encouraging results.
    Investigating the structural effect of electrospun nano-fibrous polymeric films on water vapor transmission
    Seyed Jalil Poormohammadian, Parviz Darvishi, Abdol Mohammad Ghalambor Dezfuli
    2019, 27(1):  100-109.  doi:10.1016/j.cjche.2018.02.033
    Abstract ( 449 )   PDF (2088KB) ( 59 )  
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    Electrospun polymers have many applications in the industry. However, the structure of these polymers has been less widely considered by researchers. In this work, the structural effect of electrospun and casted films of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) polymers on water vapor transmission were investigated. Sorption of water vapor was measured at 35, 60 and 80℃ and different relative humidities. The diffusion coefficients were calculated based on mass changes of the polymer sample. The water vapor transmission rate (WVTR) was also measured at 35℃ and 90% relative humidity. The results indicated that electrospun nano-fibrous polymers (ESNPs) absorb much higher water vapor compared to non-porous casted polymers. The interaction of water molecules with mentioned polymers was investigated based on Flory-Huggins theory. The Flory-Huggins interaction parameter of electrospun films was less than casted films, suggesting much better interaction of water molecules with electrospun films. It was also found that electrospun films have anomalous kinetic behavior and do not obey the Fickian diffusion model. Finally, it was revealed that ESNPs show less resistance to water vapor transmission and they are good candidates for the applications of water vapor separation using membranes.
    Optimization of the gas separation performance of polyurethane-zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology
    Hajar Taheri Afarani, Morteza Sadeghi, Ahmad Moheb, Ebrahim Nasr Esfahani
    2019, 27(1):  110-129.  doi:10.1016/j.cjche.2018.03.013
    Abstract ( 511 )   PDF (16308KB) ( 37 )  
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    In the present work, the response surface method software was used with five measurement levels with three factors. These were applied for the optimization of operating parameters that affected gas separation performance of polyurethane-zeolite 3A, ZSM-5 mixed matrix membranes. The basis of the experiments was a rotatable central composite design (CCD). The three independent variables studied were:zeolite content (0-24 wt%), operating temperature (25-45℃) and operating pressure (0.2-0.1 MPa). The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance (ANOVA). Optimal conditions for the enhancement of gas separation performances of polyurethane-3A zeolite were found to be 18 wt%, 30℃ and 0.8 MPa respectively. Under these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO2/CH4, CO2/N2 and O2/N2 selectivities were 5.8, 22.5 and 2.5, respectively. Also, the optimal conditions for improvement of the gas separation performance of polyurethane-ZSM 5 were found to be 15.64 wt%, 30℃ and 4 bar. The permeabilities of these four gases (i.e. carbon dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO2/CH4, CO2/N2 and O2/N2 selectivities were 7.8, 20.6 and 2.7 respectively.
    Preparation of an amphoteric flocculant having both high polymer content and low viscosity and its polymerization kinetics
    Shenwen Fang, Manlin Wang, Zipei Xu, Lei Zhai, Xiujun Wang, Yan Xiong
    2019, 27(1):  130-135.  doi:10.1016/j.cjche.2018.03.002
    Abstract ( 451 )   PDF (1299KB) ( 55 )  
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    It is not easy for liquid cationic flocculant diallyldimethyl-ammonium chloride (DM) homopolymer to simultaneously exhibit both low viscosity and high polymer content, which limited its application in offshore oilfield. In this paper, sodium allylsulfonate (XS) and sodium formate were used in the aqueous solution polymerization of DM. An amphoteric flocculant (PDMXS) with the properties of high polymer content (about 55 wt%) and low viscosity (efflux time measured by an Apply 4 viscometer was less than 100 s) was prepared. The optimum reaction conditions were identified as follows:the mass ratio of XS/DM was 10 wt%, the concentration of sodium formate was 2000 mg·L-1, reaction temperature was 55℃, the concentration of KPS was 0.5 wt% and the reaction time was 4 h. The polymerization kinetics was discussed. The results showed that Rp ∝[M]1.97[I]0.68[CTA]0.71 and the apparent activation energy was 72.55 kJ·mol-1.
    Reactive dividing-wall column for the co-production of ethyl acetate and n-butyl acetate
    Hongshi Li, Tong Li, Chunli Li, Jing Fang, Lihui Dong
    2019, 27(1):  136-143.  doi:10.1016/j.cjche.2018.02.023
    Abstract ( 473 )   PDF (853KB) ( 116 )  
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    Reactive dividing-wall column (RDWC) technology plays a critical role in the energy saving and high efficiency of chemical process. In this article, the process of co-producing ethyl acetate (EA) and n-butyl acetate (BA) with RDWC was studied. BA was not only the product, but also acted as entrainer to remove the water generated by the two esterification reactions. Experiments and simulations of the co-production process were carried out. It was found that the experimental results were in good agreement with the simulation results. Two kinds of RDWC structures (RDWC-FC and RDWC-RS) were proposed, and the co-production process operating parameters of the two types of RDWC were optimized by Aspen Plus respectively. The optimal operating parameters of the RDWC-FC were determined as follows:0.6 of the reflux ratio of aqueous phase (RR), 0.66 of the vapor split (RV) and 0.51 of the liquid split (RL). And the optimal operating parameters of the RDWC-RS were shown as follows:RR was 0.295 and RV was 0.61. Furthermore, the energy saving analysis of the co-production process was based on the annual output of 10000 tons of EA, compared with the traditional reaction distillation (RD) to prepare EA and BA, the reboiler duty of the RDWC-FC column could save 20.4%, TAC saving 23.6%; RDWC-RS reboiler energy consumption could save 17.0%, TAC 22.2%.
    Catalysis, kinetics and reaction engineering
    Physicochemical properties of amide-AlCl3 based ionic liquid analogues and their mixtures with copper salt
    Pengcheng Hu, Wei Jiang, Lijuan Zhong, Shufeng Zhou
    2019, 27(1):  144-149.  doi:10.1016/j.cjche.2018.06.018
    Abstract ( 365 )   PDF (855KB) ( 177 )  
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    The physicochemical properties of three different amide-AlCl3 based ionic liquid (IL) analogues and their mixtures with copper salt, such as conductivity, viscosity, density and isobutane solubility were determined over a wide range of temperatures. The effects of amide structure, amide/AlCl3 molar ratio and CuCl modification on these physicochemical properties were investigated. Results showed that the conductivity of amide-AlCl3 based IL analogues was much lower than that of traditional Et3NHCl-AlCl3 IL with same ligand/AlCl3 molar ratio due to incomplete splitting of AlCl3, whereas the density and viscosity of amide-AlCl3 based IL analogues were slightly higher. The viscosity of amide-AlCl3 based IL analogues was closely related to the amide structure, and followed the order of DMA-AlCl3 > AA-AlCl3 > NMA-AlCl3 with same amide/AlCl3 molar ratio. Meanwhile, the density of amide-AlCl3 based IL analogues ranked in the following order:AA-AlCl3 > NMA-AlCl3 > DMA-AlCl3. Increasing the amide/AlCl3 molar ratio decreased the conductivity and density, while increased the viscosity. The solubility experiment indicated that the isobutane solubility in NMA-AlCl3 was highest than that in two other IL analogues. Under the modification of CuCl, the conductivity, viscosity and density of these IL analogues increased, whereas the isobutane solubility decreased. These results provide the foundation for the development of a suitable IL analogue catalyst for isobutane alkylation.
    Electrochemical analysis and convection-enhanced mass transfer synergistic effect of MnOx/Ti membrane electrode for alcohol oxidation
    Hong Wang, Xin Wei, Yujun Zhang, Ronghua Ma, Zhen Yin, Jianxin Li
    2019, 27(1):  150-156.  doi:10.1016/j.cjche.2018.07.006
    Abstract ( 371 )   PDF (7849KB) ( 18 )  
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    The different electrocatalytic reactors could be constructed for the electrocatalytic oxidation of 2,2,3,3-tetrafluoro-1-propanol (TFP) with two typical MnOx/Ti electrodes, i.e. the electrocatalytic membrane reactor (ECMR) with the Ti membrane electrode and the electrocatalytic reactor (ECR) with the traditional Ti plate electrode. For the electro-oxidation of TFP, the conversion with membrane electrode (70.1%) in the ECMR was 3.3 and 1.7 times higher than that of the membrane electrode without permeate flow (40.8%) in the ECMR and the plate electrode (21.5%) in the ECR, respectively. Obviously, the pore structure of membrane and convection-enhanced mass transfer in the ECMR dramatically improved the catalytic activity towards the electro-oxidation of TFP. The specific surface area of porous electrode was 2.22 m2·g-1. The surface area of plate electrode was 2.26 cm2 (1.13 cm2×2). In addition, the electrochemical results showed that the mass diffusion coefficient of the MnOx/Ti membrane electrode (1.80×10-6 cm2·s-1) could be increased to 6.87×10-6 cm2·s-1 at the certain flow rate with pump, confirming the lower resistance of mass transfer due to the convection-enhanced mass transfer during the operation of the ECMR. Hence, the porous structure and convection-enhanced mass transfer would improve the electrochemical property of the membrane electrode and the catalytic performance of the ECMR, which could give guideline for the design and application of the porous electrode and electrochemical reactor.
    Process Systems Engineering and Process Safety
    Process simulation and energy integration in the mineral carbonation of blast furnace slag
    Jianqiu Gao, Chun Li, Weizao Liu, Jinpeng Hu, Lin Wang, Qiang Liu, Bin Liang, Hairong Yue, Guoquan Zhang, Dongmei Luo, Siyang Tang
    2019, 27(1):  157-167.  doi:10.1016/j.cjche.2018.04.012
    Abstract ( 552 )   PDF (4882KB) ( 139 )  
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    Large quantities of blast furnace (BF) slag and CO2 are discharged annually from iron and steel industries, along with a large amount of waste heat. The mineral carbonation of BF slag can not only reduce emissions of solid waste but also realize the in-situ fixation of CO2 with low energy consumption if integrated with the waste heat utilization. In this study, based on our previous works, Aspen Plus was employed to simulate and optimize the carbonation process and integrate the process energy. The effects of gehlenite extraction, MgSO4 carbonation, and aluminum ammonium sulfate crystallization were studied systematically. The simulation results demonstrate that 2.57 kg of BF slag can sequester 1 kg of CO2, requiring 5.34 MJ of energy (3.3 MJ heat and 2.04 MJ electricity), and this energy includes the capture of CO2 from industrial flue gases. Approximately 60 kg net CO2 emission reduction could be achieved for the disposal of one ton of BF slag. In addition, the by-product, aluminum ammonium sulfate, is a high value-added product. Preliminary economic analysis indicates that the profit for the whole process is 1127 CNY per ton of BF slag processed.
    Chemical Engineering Thermodynamics
    Salt effect on the liquid-liquid equilibrium of the ternary (water + phenol + methyl isobutyl ketone) system: Experimental data and correlation
    Yun Chen, Kangning Xiong, Shuai Shen, Huimin Wang, Shaoming Zhou, Libo Li
    2019, 27(1):  168-173.  doi:10.1016/j.cjche.2018.02.013
    Abstract ( 459 )   PDF (491KB) ( 65 )  
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    The effects of NaCl, KCl and Na2SO4 on the liquid-liquid equilibrium (LLE) data for the ternary system, water + phenol + methyl isobutyl ketone, were determined at 0.101 MPa and 333.15 K and 343.15 K. The nonrandom two-liquid (NRTL) model was used to correlate the experimental data and to yield corresponding binary interaction parameters for these salt containing systems. The Hand and Othmer-Tobias equations were used to confirm the dependability of the determined LLE data in this work. Distribution coefficient and selectivity were used to evaluate the extraction performance of methyl isobutyl ketone with the existence of salt. The magnitude of salt effect on the water + phenol + methyl isobutyl ketone (MIBK) system is in the following order:Na2SO4 > NaCl > KCl.
    All-silica zeolites screening for capture of toxic gases from molecular simulation
    Zhiguo Yan, Sai Tang, Xumiao Zhou, Li Yang, Xingqing Xiao, Houyang Chen, Yuanhang Qin, Wei Sun
    2019, 27(1):  174-181.  doi:10.1016/j.cjche.2018.02.025
    Abstract ( 427 )   PDF (6397KB) ( 93 )  
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    The exhaust gases, including SO2, NH3, H2S, NO2, NO, and CO, are principal air pollutants due to their severe harms to the ecological environment. Zeolites have been considered as good absorbent candidates to capture the six exhaust gases. In this work, we performed grand canonical ensemble Monte Carlo (GCMC) simulations to examine the capability of 95 kinds of all-silica zeolites in the removal of the six toxic gases, and to predict the adsorption isotherms of the six gases on all the zeolites. The simulation results showed that, H2S, NO, NO2, CO and NH3 are well-captured by zeolite structures with accessible surface area of 1600-1800 m2·g-1 and pore diameter of 0.6-0.7 nm, such as AFY and PAU, while SO2 is well-adsorbed by zeolites containing larger accessible surface area (1700-2700 m2·g-1) and pore diameter (0.7-1.4 nm) at room temperature and an atmospheric pressure. However, at saturated adsorption, zeolites RWY, IRR, JSR, TSC, and ITT are found to exhibit better abilities to capture these gases. Our study provides useful computational insights in choosing and designing zeolite structures with high performance to remove toxic gases for air purification, thereby facilitating the development and application of exhaust gas-processing technology in green industry.
    Integrated system of comprehensive utilizing the concentrated brine of Yuncheng salt-lake basing on salt-forming diagram
    Huan Zhou, Jingjing Tang, Jian Guo, Yaping Dai, Guangbi Li, Bo Yan
    2019, 27(1):  182-190.  doi:10.1016/j.cjche.2018.03.008
    Abstract ( 442 )   PDF (3354KB) ( 38 )  
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    The comprehensive utilization and environment-friendliness of processes for recovering fresh water or valuable salt from seawater, salt-lakes, or mineral deposits are of utmost importance for sustainable development. One primitive sustainable process for recovering salt from sodium-sulfate-type brine in Yuncheng salt lake had been considered one of the greatest inventions of ancient China, however, the replaced process of mass extraction of single Na2SO4 in recent years, has reduced a large amount of residual brine. In this research, relying on the salt-forming diagram in the non-equilibrium state, the technical secrets of ancient salt processes were uncovered, and a new comprehensive utilization system was proposed and tested experimentally. The new system includes a vacuum salt-making process and a normal pressure kieserite process, which can gradually eliminate the existed waste liquid and aid in the sustainable development of the Yuncheng salt-lake. The continuous experiment of salt-making process running stably in the double salt region without double salt formation, which proves the feasibility of salt-forming diagram applied in industrial process. Thus salt-forming diagram would be extremely valuable to industry process design and control, especially, the treatment of concentrated brine.
    Biotechnology and Bioengineering
    Immobilization of organophosphorus hydrolase enzyme by covalent attachment on modified cellulose microfibers using different chemical activation strategies: Characterization and stability studies
    Meisam Sharifi, Seyed-Mortaza Robatjazi, Minoo Sadri, Jafar Mohammadian Mosaabadi
    2019, 27(1):  191-199.  doi:10.1016/j.cjche.2018.03.023
    Abstract ( 453 )   PDF (1087KB) ( 186 )  
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    The plant cellulose powder was activated by two different methods using 1,4-butanediol diglycidyl ether (BTDE) and 1,1'-Carbonyldiimidazole (CDI) as the chemical coupling agents. Organophosphorus hydrolase (OPH) from Flavobacterium ATCC 27551 was immobilized on any of activated support through covalent bonding. The optimal conditions of affecting parameters on enzyme immobilization in both methods were found, and it was demonstrated that the highest activity yields of immobilized OPH onto epoxy and CDI treated cellulose were 68.32% and 73.51%, respectively. The surface treatment of cellulose via covalent coupling with BTDE and CDI agents was proved by FTIR analysis. The kinetic constants of the free and immobilized enzymes were determined, and it was showed that both immobilization techniques moderately increased the Km value of the free OPH. The improvements in storage and thermal stability were investigated and depicted that the half-life of immobilized OPH over the surface of epoxy modified cellulose had a better growth compared to the free and immobilized enzymes onto CDI treated support. Also, the pH stability of the immobilized preparations was enhanced relative to the free counterpart and revealed that all enzyme samples would have the same optimum pH value for stability at 9.0. Additionally, the immobilized OPH onto epoxy and CDI activated cellulose retained about 59% and 68% of their initial activity after ten turns of batch operation, respectively. The results demonstrated the high performance of OPH enzyme in immobilized state onto an inexpensive support with the potential of industrial applications.
    Energy, Resources and Environmental Technology
    Effect on anaerobic digestion performance of corn stover by freezing-thawing with ammonia pretreatment
    Hairong Yuan, Yanyan Lan, Jialin Zhu, Akiber Chufo Wachemo, Xiujin Li, Liang Yu
    2019, 27(1):  200-207.  doi:10.1016/j.cjche.2018.04.021
    Abstract ( 343 )   PDF (2142KB) ( 66 )  
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    In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion (AD). This study was aimed to analyze the effectiveness of freezing-thawing with ammonia pretreatment on substance degradation and AD performance of corn stover. Three ammonia concentrations (2%, 4%, and 6%) with two different moisture contents (50% and 70%) were used to pretreat the corn stover at two temperatures (-20℃ and 20℃). The result showed that an optimum pretreatment condition for corn stover was at the temperature of -20℃, moisture content of 70% and ammonia concentration of 2%. Under the optimum pretreatment condition, the maximum biomethane yield reached 261 ml·(g VS)-1, which was 41.08% higher than that of the untreated. Under different pretreatment conditions, the highest loss of lignin at -20℃ with 2% ammonia concentration was 63.36% compared with the untreated. The buffer capacity of AD system was also improved after the freezing-thawing with ammonia pretreatment. Therefore, the freezing-thawing with ammonia pretreatment can be used to improve AD performance for corn stover. This study provides further insight for exploring an efficient freezing-thawing with ammonia pretreatment strategy to enhance AD performance for the practical application.
    High performance electrocoagulation process in treating palm oil mill effluent using high current intensity application
    Mohd Nasrullah, A. W. Zularisam, Santhana Krishnan, Mimi Sakinah, Lakhveer Singh, Yap Wing Fen
    2019, 27(1):  208-217.  doi:10.1016/j.cjche.2018.07.021
    Abstract ( 428 )   PDF (3376KB) ( 52 )  
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    Electrocoagulation process using high current intensity to treat palm oil mill effluent (POME) was investigated in this study. Various operating parameters such as electrolysis time, inter-electrode distance and initial pH were carried out to determine the efficient process condition on the removal of chemical oxygen demand (COD), biological oxygen demand (BOD) and suspended solids (SS). The highest treatment was achieved at 50 min with the removal efficiencies for COD, BOD and SS obtained as 85%, 83%, and 84%, respectively. More than 50 min treatment showed the fluctuated trends of removal efficiencies which can be considered insignificant. The application of higher current resulted in higher removals of organics while the gas bubbles also assisted in removing the pollutant particles by floatation. In an inter-electrode distance study, the removal efficiency decreased when inter-electrode distance was either higher or lower than 10 mm due to the increase of solution resistance and the decrease of anode active surface area. In initial pH study, it was found that high removal efficiencies were achieved in slightly acidic POME sample rather than in neutral or basic condition. An electrocoagulation process by using the optimum operating parameters was able to remove COD, BOD and SS up to 95%, 94% and 96% respectively. The experimental results confirm that application of high current intensity in electrocoagulation provided high treatment efficiency at a reduced reaction time.
    Devise of a W serpentine shape tube heat exchanger in a hard chromium electroplating process
    Surasit Tanthadiloke, Paisan Kittisupakorn, Pannee Boriboonsri, Iqbal M. Mujtaba
    2019, 27(1):  218-225.  doi:10.1016/j.cjche.2018.03.025
    Abstract ( 400 )   PDF (1569KB) ( 24 )  
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    In a hard chromium electroplating process, a heat exchanger is employed to remove the heat produced from the high current intensity in an electroplating bath. Normally, a conventional U shape heat exchanger is installed in the bath, but it provides low heat removal. Thus, this study designs a novel W serpentine shape heat exchanger with identical heat transfer area to the conventional one for increasing heat removal performance. The performance of the heat exchange is tested with various flow velocities in a cross-section in range of 1.6 to 2.4 m·s-1. Mathematical models of this process have been formulated in order to simulate and evaluate the heat exchanger performance. The results show that the developed models give a good prediction of the plating solution and cooling water temperature, and the novel heat exchanger provides better results at any flow velocity. In addition, the W serpentine shape heat exchanger has been implemented in a real hard chromium electroplating plant. Actual data collected have shown that the new design gives higher heat removal performance compared with the U shape heat exchanger with identical heat transfer area; it removes more heat out of the process than the conventional one of about 23%.
    Materials and Product Engineering
    Mesoporous activated carbon-zeolite composite prepared from waste macadamia nut shell and synthetic faujasite
    Surachai Wongcharee, Vasantha Aravinthan, Laszlo Erdei
    2019, 27(1):  226-236.  doi:10.1016/j.cjche.2018.06.024
    Abstract ( 473 )   PDF (3778KB) ( 150 )  
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    Novel activated carbon-zeolite composite adsorbent was prepared from macadamia shell bio-waste and synthetic zeolite X using hydrothermal treatment. Characterisation studies revealed mainly mesoporous structure with 418 m2·g-1 BET surface area with faujasite clusters on the carbon carrier. Sorption capacity for methylene blue model pollutant increased from 85 to 97 mg·g-1 with the temperature increase from 25 to 45℃, and improved with increasing pH. Nonlinear regression analyses found accurate fit to the pseudo-first-order kinetics model and intra-particle diffusion rate controlling mechanism. Excellent fits to the Jovanovic isotherm model indicated monolayer coverage on chiefly homotattic surfaces with variable potential. The thermodynamic analysis confirmed spontaneous and endothermic physisorption process. The spent adsorbent was regenerated with 20% capacity loss over five reuse cycles. Although the adsorbent was developed for ammonia, heavy metal and organic matter removal from water sources, the results also indicate good performance in cationic dye removal from wastewaters.