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Table of Content
28 May 2017, Volume 25 Issue 5
    Fluid Dynamics and Transport Phenomena
    Effect of surfactant on zeta potential and rheology behavior of methylene bis (thiocyanate) suspension concentrate
    Jianfeng Hu, Yan Cai, Shan Lu, Jiezhen Xu, Zhongrun Yun, Jianheng Huang, Yuliang Wen, Jinqing Qu
    2017, 25(5):  541-546.  doi:10.1016/j.cjche.2016.08.008
    Abstract ( 1413 )   PDF (1078KB) ( 73 )  
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    Methylene bis(thiocyanate) (MBT) is insoluble in water, so suspension concentrate (SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants, such as Morwet D425 (D425) and Morwet EFW (EFW) (two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution (pH=4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate (γ) and viscosity (η) was studied according to Herschel-Bulkley model:η=η0+k/γ, and the relationship between shear rate (γ) and shear force (τ) was investigated according to:τ=τ0+n. It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.
    Correlating thermal conductivity of pure hydrocarbons and aromatics via perceptron artificial neural network (PANN) method
    Mostafa Lashkarbolooki, Ali Zeinolabedini Hezave, Mahdi Bayat
    2017, 25(5):  547-554.  doi:10.1016/j.cjche.2016.08.025
    Abstract ( 1079 )   PDF (729KB) ( 53 )  
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    Accurate estimation of liquid thermal conductivity is highly necessary to appropriately design equipments in different industries. Respect to this necessity, in the current investigation a feed-forward artificial neural network (ANN) model is examined to correlate the liquid thermal conductivity of normal and aromatic hydrocarbons at the temperatures range of 257-338 K and atmospheric pressure. For this purpose, 956 experimental thermal conductivities for normal and aromatic hydrocarbons are collected from different previously published literature. During the modeling stage, to discriminate different substances, critical temperature (Tc), critical pressure (Pc) and acentric factor (ω) are utilized as the network inputs besides the temperature. During the examination, effects of different transfer functions and number of neurons in hidden layer are investigated to find the optimum network architecture. Besides, statistical error analysis considering the results obtained from available correlations and group contribution methods and proposed neural network is performed to reliably check the feasibility and accuracy of the proposed method. Respect to the obtained results, it can be concluded that the proposed neural network consisted of three layers namely, input, hidden and output layers with 22 neurons in hidden layer was the optimum ANN model. Generally, the proposed model enables to correlate the thermal conductivity of normal and aromatic hydrocarbons with absolute average relative deviation percent (AARD), mean square error (MSE), and correlation coefficient (R2) of lower than 0.2%, 1.05×10-7 and 0.9994, respectively.
    Laminar natural convection characteristics in an enclosure with heated hexagonal block for non-Newtonian power law fluids
    Krunal M. Gangawane, B. Manikandan
    2017, 25(5):  555-571.  doi:10.1016/j.cjche.2016.08.028
    Abstract ( 1425 )   PDF (8773KB) ( 67 )  
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    This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature (CWT) or uniform heat flux (UHF) thermal conditions. Governing equations (mass, momentum and energy) are solved by using finite volume method (FVM) with 3rd order accurate QUICK discretization scheme and SIMPLE algorithm for range of field pertinent parameters such as, Grashof number (103Gr ≤ 106), Prandtl number (1 ≤ Pr ≤ 100) and power law index (0.5 ≤ n ≤ 1.5). The analysis of momentum and heat transfer characteristics are delineated by evolution of streamlines, isotherms, variation of average Nusselt number value and Colburn factor for natural convection (jnH). A remarkable change is observed on fluid flow and thermal distribution pattern in cavity for both thermal conditions. Nusselt number shows linear variation with Grashof and Prandtl numbers; while rate of heat transfer by convection decreases for power law index value. Higher heat transfer rate can be achieved by using uniform heat flux condition. A Nusselt number correlation is developed for possible utilization in engineering/scientific design purpose.
    Separation Science and Engineering
    Modification of CaO-based sorbents prepared from calcium acetate for CO2 capture at high temperature
    Xiaotong Liu, Junfei Shi, Liu He, Xiaoxun Ma, Shisen Xu
    2017, 25(5):  572-580.  doi:10.1016/j.cjche.2016.10.015
    Abstract ( 1270 )   PDF (1494KB) ( 43 )  
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    CaO-based sorbent is considered to be a promising candidate for capturing CO2 at high temperature. However, the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In this study, CaO was derived from calcium acetate (CaAc2), which was doped with different elements (Mg, Al, Ce, Zr and La) to improve the cyclic stability. The carbonation conversion and cyclic stability of sorbents were tested by thermogravimetric analyzer (TGA). The sorbents were characterized by N2 isothermal adsorption measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the cyclic stabilities of all modified sorbents were improved by doping elements, while the carbonation conversions of sorbents in the 1st cycle were not increased by doping different elements. After 22 cycles, the cyclic stabilities of CaO-Al, CaO-Ce and CaO-La were above 96.2%. After 110 cycles, the cyclic stability of CaO-Al was still as high as 87.1%. Furthermore, the carbonation conversion was closely related to the critical time and specific surface area.
    Evaluation of hollow fiber T-type zeolite membrane modules for ethanol dehydration
    Xuerui Wang, Ji Jiang, Dezhong Liu, Youquan Xue, Chun Zhang, Xuehong Gu
    2017, 25(5):  581-586.  doi:10.1016/j.cjche.2016.10.025
    Abstract ( 1301 )   PDF (3890KB) ( 59 )  
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    This work presents the design of hollow fiber T-type zeolite membrane modules with different geometric configurations. The module performances were evaluated by pervaporation dehydration of ethanol/water mixtures. Strong concentration polarization was found for the modules with big membrane bundles. The concentration polarization was enhanced at high temperature due to the higher water permeation flux. The increase of feed flow could improve water permeation flux for the membrane modules with small membrane bundle. Computational fluid dynamics was used to visualize the flow field distribution inside of the modules with different configurations. The membrane module with seven bundles exhibited highest separation efficiency due to the uniform distribution of flow rate. The packing density could be 10 times higher than that of the tubular membrane module. The hollow fiber membrane module exhibited good stability for ethanol dehydration.
    Synthesis of a novel functional group-bridged magnetized bentonite adsorbent: Characterization, kinetics, isotherm, thermodynamics and regeneration
    Zhichao Lou, Wei Zhang, Xiaodan Hu, Haiqian Zhang
    2017, 25(5):  587-594.  doi:10.1016/j.cjche.2016.10.010
    Abstract ( 1484 )   PDF (4276KB) ( 40 )  
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    A novel magnetic adsorbent was synthesized by magnetizing bentonite by APTES-Fe3O4 via a functional groupbridged interaction. The characterization of APTES-Fe3O4/bentonite was conducted via transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FT-IR), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM), zeta potential analysis and Brunner-Emmet-Teller (BET). The APTES-Fe3O4/bentonite was assessed as adsorbents for methylene blue (MB) with a high adsorption capacity (91.83 mg·g-1). Factors affecting the adsorption of MB (such as pH, equilibrium time, temperature and initial concentration) were investigated. The adsorption process completely reaches equilibrium after 120 min and the maximum sorption is achieved at pH 8.0. The adsorption trend follows the pseudosecond order kinetics model. The adsorption data gives good fits with Langmuir isotherm model. The parameter factor RL falls between 0 and 1, indicating the adsorption of MB is favorable. The adsorption process is endothermic with positive ΔH0 values. The positive values of ΔG0 confirm the affinity of the adsorbent towards MB, and suggest an increased randomness at the solid-liquid interface during the adsorption process. Regeneration of the saturated adsorbent was easily carried out via gamma-irradiation.
    Synthesis, gas adsorption and reliable pore size estimation of zeolitic imidazolate framework-7 using CO2 and water adsorption
    Mahdi Niknam Shahrak, Morteza Niknam Shahrak, Akbar Shahsavand, Nasser Khazeni, Xiaofei Wu, Shuguang Deng
    2017, 25(5):  595-601.  doi:10.1016/j.cjche.2016.10.012
    Abstract ( 1402 )   PDF (939KB) ( 306 )  
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    Reliable estimation of the pore size distribution (PSD) in porous materials such as metal-organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs) is crucial for accurately assessing adsorption capacity and corresponding selectivity. In this study, the so-called zeolitic imidazolate framework-7 (ZIF-7) is successfully synthesized via relatively fast and convenient microwave technique. The morphology and structure of the obtained MOF were characterized by XRD, SEM and N2 and CO2 adsorption/desorption isotherms at 77 K and 0℃ respectively. Then, to determine the PSD of the fabricated MOF, carbon dioxide isotherms are experimentally measured at various temperatures up to atmospheric pressure. Afterward, the experimental CO2 isotherms data are utilized in two recently proposed in-house algorithms of SHN1 and SHN2 to extract the true PSD of manufactured ZIF-7. The obtained results revealed that median pore diameter of the fabricated ZIF-7 is estimated around 0.404 nm and 0.370 nm by using CO2 isotherms at 273 K and 298 K respectively. These values are in good agreement with the real pore diameter of 0.42 nm. Moreover, experimental data of water adsorption isotherms over four different MOFs, borrowed from literature, are employed to illustrate further effectiveness of the above algorithms on successful determination of the corresponding pore size distributions. All predicted PSDs are proved to be in good agreement with those obtained from independent methods such as topology and morphology studies.
    Catalysis, Kinetics and Reaction Engineering
    Catalytic methanation of syngas over Ni-based catalysts with different supports
    Yincong Liu, Lingjun Zhu, Xiaoliu Wang, Shi Yin, Furong Leng, Fan Zhang, Haizhou Lin, Shurong Wang
    2017, 25(5):  602-608.  doi:10.1016/j.cjche.2016.10.019
    Abstract ( 1621 )   PDF (4745KB) ( 47 )  
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    Co-precipitation method was selected for the preparation of Ni/Al2O3, Ni/ZrO2 and Ni/CeO2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H2-TPD, TEM and H2-TPR. The results showed that the catalytic activity at low temperature followed the order:Ni/Al2O3 > Ni/ZrO2 > Ni/CeO2. Ni/Al2O3 catalyst presented the best catalytic performance with the highest CH4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.
    Zn-Ca-Al mixed oxide as efficient catalyst for synthesis of propylene carbonate from urea and 1, 2-propylene glycol
    Sen Liu, Suhong Sun, Xuehui Tian, Peiyong Sun, Shenghong Zhang, Zhilong Yao
    2017, 25(5):  609-616.  doi:10.1016/j.cjche.2016.11.003
    Abstract ( 1402 )   PDF (2055KB) ( 60 )  
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    A series of Zn-Ca-Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate (PC) from 1,2-propylene glycol (PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn-Ca-Al catalysts, according to the time dependences of reaction intermediates and products.
    Process Systems Engineering and Process Safety
    An improved flexible tolerance method for solving nonlinear constrained optimization problems: Application in mass integration
    Alice Medeiros Lima, Wu Hong Kwong, Antonio José Gonçalves Cruz
    2017, 25(5):  617-631.  doi:10.1016/j.cjche.2016.07.019
    Abstract ( 1369 )   PDF (3144KB) ( 57 )  
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    This paper proposes the use of the flexible tolerance method (FTM) modified with adaptive Nelder-Mead parameters and barrier to solve constrained optimization problems. The problems used to analyze the performance of the methods were taken from G-Suite functions, and the methods with the best performance were applied in mass integration problems. Four methods were proposed:(1) flexible tolerance method (FTM) using adaptive parameters (FTMA), (2) flexible tolerance method with scaling (FTMS) and with adaptive parameters (FTMAS), (3) FTMS including the barrier modification (MFTMS) and (4) MFTMS hybridized with PSO (MFTMS-PSO). The success rates of these methods were 100% (MFTMS), 85% (MFTMS-PSO), 40% (FTMAS) and 30% (FTMA). Numerical experiments indicated that the MFTMS could efficiently and reliably improve the accuracy of global optima. In mass integration, the method was able, from current process situation, to reach the optimum process configuration that includes integration issues, which was not possible using FTM in its standard formulation. The hybridization of FTMS with PSO (without barrier), FTMS-PSO, was also able to solve mass integration problems efficiently.
    An optimal filter based MPC for systems with arbitrary disturbances
    Haokun Wang, Zuhua Xu, Jun Zhao, Aipeng Jiang
    2017, 25(5):  632-640.  doi:10.1016/j.cjche.2016.09.011
    Abstract ( 1148 )   PDF (855KB) ( 31 )  
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    In this study, a linear model predictive control (MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance õrejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics.
    Chemical Engineering Thermodynamics
    Measurement and calculation of solubility of quinine in supercritical carbon dioxide
    Fatemeh Zabihi, Mehrdad Mirzajanzadeh, Jingfu Jia, Yaping Zhao
    2017, 25(5):  641-645.  doi:10.1016/j.cjche.2016.10.003
    Abstract ( 1174 )   PDF (853KB) ( 44 )  
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    Solubility of quinine in supercritical carbon dioxide (SCCO2) was experimentally measured in the pressure range of 8 to 24 MPa, at three constant temperatures:308.15 K, 318.15 K and 328.15 K. Measurement was carried out in a semi-dynamic system. Experimental data were correlated by iso-fugacity model (based on cubic equations of state, CEOS), Modified Mendez-Santiago-Teja (MST) and Modified Bartle semi-empirical models. Two cubic equations of state:Peng-Robinson (PR) and Dashtizadeh-Pazuki-Ghotbi-Taghikhani (DPTG) were adopted for calculation of equilibrium parameters in CEOS modeling. Interaction coefficients (kij & lij) of van der Waals (vdW) mixing rules were considered as the correlation parameters in CEOS-based modeling and their contribution to the accuracy of model was investigated. Average Absolute Relative Deviation (AARD) between correlated and experimental data was calculated and compared as the index of validity and accuracy for different modeling systems. In this basis it was realized that the semi-empirical equations especially Modified MST can accurately support the theoretical studies on phase equilibrium behavior of quinine-SCCO2 media. Among the cubic equations of state DPGT within two-parametric vdW mixing rules provided the best data fitting and PR within one-parametric vdW mixing rules demonstrated the highest deviation respecting to the experimental data. Overall, in each individual modeling system the best fitting was observed on the data points attained at 318 K, which could be perhaps due to the moderate thermodynamic state of supercritical phase.
    Solubility and metastable zone width measurement of 3, 4-bis (3-nitrofurazan-4-yl) furoxan (DNTF) in ethanol+water
    Lizhen Chen, Liang Song, Guanchao Lan, Jianlong Wang
    2017, 25(5):  646-651.  doi:10.1016/j.cjche.2016.08.015
    Abstract ( 1252 )   PDF (500KB) ( 65 )  
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    The solubility and supersolubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in ethanol+water at different operation were determined by laser monitoring system under atmospheric pressure to study the metastable zone width (MSZW). The modified Apelblat equation was adopted to correlate the experimental solubility data, and the correlation result showed perfect consistent with the experimental data. The standard dissolution enthalpy, standard dissolution entropy and Gibbs energy were calculated according to the experimental solubility data. The effect of the cooling rate, stirring rate, temperature and the concentration of ethanol+water on the MSZW was studied. It was found that the MSZW of DNTF increased with the increasing cooling rate, decreasing temperature, decreasing stirring rate and decreasing ratio of water. And the apparent nucleation order of DNTF in ethanol+water was calculated by the relationship between the cooling rate and the MSZW.
    Biotechnology and Bioengineering
    Partition coefficient prediction of Baker's yeast invertase in aqueous two phase systems using hybrid group method data handling neural network
    Carlos Eduardo de Araújo Padilha, Sérgio Dantas de Oliveira Júnior, Domingos Fabiano de Santana Souza, Jackson Araújo de Oliveira, Gorete Ribeiro de Macedo, Everaldo Silvino dos Santos
    2017, 25(5):  652-657.  doi:10.1016/j.cjche.2016.07.015
    Abstract ( 1039 )   PDF (490KB) ( 48 )  
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    A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG (1500-6000 Da), pH (4.0-7.0), percentage of PEG (10.0-20.0 w/w), percentage of MgSO4 (8.0-16.0 w/w), percentage of the cell homogenate (10.0-20.0 w/w) and the percentage of MnSO4 (0-5.0 w/w) added as cosolute. The network evaluation was carried out comparing the partition coefficients obtained from the hybrid GMDH neural network with the experimental data using different statistical metrics. The hybrid GMDH neural network model showed better fitting (AARD=32.752%) as well as good generalization capacity of the partition coefficients of the ATPS than the original GMDH network approach and a BPANN model. Therefore hybrid GMDH neural network model appears as a powerful tool for predicting partition coefficients during downstream processing of biomolecules.
    Energy, Resources and Environmental Technology
    Influence of Na+, K+, Mg2+, Ca2+, and Fe3+ on filterability and settleability of drilling sludge
    Liyan Liu, Hao Yan, Wei Tan, Guorui Zhu
    2017, 25(5):  658-664.  doi:10.1016/j.cjche.2016.10.008
    Abstract ( 1374 )   PDF (1921KB) ( 51 )  
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    Solid-liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na+, K+, Mg2+, Ca2+, and Fe3+on drilling sludge filterability and settleability was investigated in our research. The water content, filtration rate, supernatant volume and supernatant turbidity were measured to evaluate the filterability and settleability of drilling sludge. Meanwhile, the zeta potential, specific surface area of sludge flocs, particle size distribution and Fourier-transformed infrared spectra were employed to clarify the influencing mechanism. The experimental results showed that the filterability and settleability of drilling sludge were related to concentration and types of cations. Mg2+, Ca2+, and Fe3+performed better than Na+, K+, and the cations with smaller hydrated radius got superior solid-liquid separation behavior at same valence. Finally, the spectra indicated that no chemical adsorption occurred between inorganic cations and drilling sludge flocs. The variation of surface charge and flocs growth after adding different inorganic cations were the reasons for the changes of the filterability and settleability.
    Catalytic ozonation of thymol in reverse osmosis concentrate with core/shell Fe3O4@SiO2@Yb2O3 catalyst: Parameter optimization and degradation pathway
    Liang Wang, Anqi Liu, Zhaohui Zhang, Bin Zhao, Yingming Xia, Yun Tan
    2017, 25(5):  665-670.  doi:10.1016/j.cjche.2016.10.017
    Abstract ( 1075 )   PDF (1764KB) ( 58 )  
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    In this work, a novel catalyst of Fe3O4@SiO2@Yb2O3 was prepared and the degradation of thymol in reverse osmosis concentrate using ozonation was explored. The operational parameters, such as ozone dosage (8-48 mg·min-1), initial thymol concentration (20-100 mg·L-1), initial pH value (3-11), and catalyst Fe3O4@SiO2@Yb2O3 dosage (0.2-1.0 g), were studied focusing on the thymol degradation and COD removal. The results indicated that the increase in ozone dosage, initial pH value, and Fe3O4@SiO2@Yb2O3 dosage accelerated the thymol degradation and COD removal, while the increase in initial thymol concentration hampered the effect of ozonation. A pathway of thymol degradation by catalytic ozonation was proposed based on the intermediates detected by gas chromatography-mass spectrometer and ion chromatography. This paper can provide basic data and technical alternative for pollutant removal from reverse osmosis concentrate by ozonation.
    The effect of transition metal ions (M2+=Mn2+, Ni2+, Co2+, Cu2+) on the chemical synthesis polyaniline as counter electrodes in dye-sensitized solar cells
    Kezhong Wu, Lei Chen, Weizhen Cui, Bei Ruan, Mingxing Wu
    2017, 25(5):  671-675.  doi:10.1016/j.cjche.2016.10.018
    Abstract ( 1130 )   PDF (2442KB) ( 106 )  
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    The effect of transition metal ions (M2+=Mn2+, Ni2+, Co2+, Cu2+) on the chemical synthesis of polyaniline (PANI) used as a platinum-free counter electrode (CE) in dye-sensitized solar cells (DSSCs) was investigated. PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide (I-/I3 -) redox couples. The power conversion efficiency (η) of PANI CEs doped with Mn2+, Ni2+, Co2+ (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Ca2+ decreased the power conversion efficiency of PANI CE (PANI-Ca2+ η=1.41%). The electrical properties of the PANI, PANI-Ni2+, PANI-Co2+, PANI-Mn2+ and PANI-Ca2+ were studied by cyclic voltammetry (CV), impedance (EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions (M2+=Mn2+, Ni2+, Co2+, Ca2+). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.
    Application of response surface methodology for optimization of purge gas recycling to an industrial reactor for conversion of CO2 to methanol
    Hadiseh Khalilpourmeymandi, Azadeh Mirvakili, Mohammad Reza Rahimpour, Alireza Shariati
    2017, 25(5):  676-687.  doi:10.1016/j.cjche.2016.10.020
    Abstract ( 1268 )   PDF (5205KB) ( 113 )  
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    Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately 15.018 t·h-1 in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen, 20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration (DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology (RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration (CRC) which therefore shows the superiority of applying DRC to CRC.