Loading...
Welcome to visit The Chinese Journal of Process Engineering, Today is

Table of Content

    28 September 2021, Volume 21 Issue 9
    Previous Issue    Next Issue
    Contents
    Cover and Contents
    The Chinese Journal of Process Engineering. 2021, 21(9):  0. 
    Asbtract ( )   PDF (1116KB) ( )  
    Related Articles | Metrics
    Reviews
    Research status of strengthening methods for gas hydrate formation process
    Qi ZHAO Zhaoyang CHEN Zhiming XIA Yu ZHANG Chungang XU Xiaosen LI
    The Chinese Journal of Process Engineering. 2021, 21(9):  993-1002.  DOI: 10.12034/j.issn.1009-606X.220296
    Asbtract ( )   PDF (1562KB) ( )  
    Related Articles | Metrics
    Based on the special physical and chemical properties of hydrate, as a new technology, method of gas hydrate is widely used in many fields, such as desalination, solid state storage and transportation of natural gas, gas separation, carbon dioxide capture and storage, etc. But due to the harsh conditions of hydrate formation, its formation rate and gas storage capacity are still far behind that of commercial applications, so special technical means are needed to reduce hydrate formation conditions and strengthen hydrate formation rate and gas storage capacity. In this work, the research status of strengthening methods for hydrate formation process is reviewed from three aspects: mechanical strengthening, outfield action and additives, and the development of technology in the future is prospected. From the point of view of the strengthening method, the mechanical strengthening technology is relatively mature, but the energy consumption required by mechanical stirring and the heat energy generated by the stirring process are both large, and increase geometrically with the increase of the device. The most extensive research on the reinforcement of additives, the effect is relatively ideal, but the reinforcement method of additives will inevitably bring new pollution to the system or products, not conducive to the actual promotion and application. There are few studies on field reinforcement, which are still in the experimental and even theoretical stage, and there is still a large space for development and improvement.
    Research progress of regulators in iron mineral flotation
    Mingyang LI Ze CHEN De LIAN Xiangpeng GAO Hongming LONG Xiong TONG
    The Chinese Journal of Process Engineering. 2021, 21(9):  1003-1011.  DOI: 10.12034/j.issn.1009-606X.220275
    Asbtract ( )   PDF (834KB) ( )  
    Related Articles | Metrics
    With the continual mining of iron ore, the simple and easy separation iron ore reserve continues decreasing, while the occupy of complex refractory iron ore increases year by year. Rational exploitation and efficient utilization of complex refractory iron ore is the focus problem of the steel industry nowadays. Flotation is one of the most effective beneficiation methods for iron ores. It possesses high separation efficiency, high hoist scope of concentrate grade and recovery rate etc., especially for fine grain ores. The effective selection and utilization of flotation reagents is one of the important methods to improve the separation performance. The flotation reagent of iron ore has developed rapidly in recent years with increasing the ratio of refractory iron ore. This work summarized the research progress of iron ore flotation regulators in recent years, highlighted the research progress of flocculants, dispersants, activators, and inhibitors in iron ore flotation, and discussed their important role. Aiming at the complex refractory iron ore separation, especially the iron containing silicates type iron ore flotation, suffers from serious problems of routine regulators, such as poor selectivity and low separation efficiency etc. To explore and research excellent selectivity, high separation efficiency, wide source, non-toxic, and economically feasible novel modifiers and their compounds will be the research emphasis of iron ore flotation regulators.
    Flow & Transfer
    Multi-scale CFD simulation of fluidization characteristics in a methanol-to-olefin fluidized bed
    Kun HONG Manqian CAO Wenxuan WANG Ya'nan GAO
    The Chinese Journal of Process Engineering. 2021, 21(9):  1012-1022.  DOI: 10.12034/j.issn.1009-606X.221187
    Asbtract ( )   PDF (2353KB) ( )  
    Related Articles | Metrics
    In recent years, China has successfully developed coal-based methanol to olefins (MTO) production processes and technologies, which has promoted the rapid development of the coal-to-olefins industry and guaranteed national energy security. The fluidized bed reactor is the core reaction device for the industrial production of methanol to olefins. It is of great significance to deeply understand the fluidization characteristics of the MTO fluidized bed through computational fluid dynamics. It can give more accurate guide for optimization and amplification of MTO fluidized bed. In this work, the multi-scale computational fluid dynamics (CFD) method which is coupling of bubble-based EMMS drag and traditional TFM is adopted to perform 3D simulation of the multi-phase flow behavior inside an industrial-scale MTO fluidized bed. This multi-scale CFD method involves in the influence of the bubble-based structure on the gas-solid drag coefficient. Thus, it can more accurately predict the "S-shaped" distribution of the axial particle concentration inside the MTO fluidized bed, which is consistent with experimental data. The predicted radical distribution of particle concentration presents the classic "core-annulus" flow structure. The predicted distribution of the averaged gas/particle axial-velocity in the radial direction is also mutually confirmed with the actual situation. This multi-scale CFD method significantly improves the predictive ability of the traditional TFM based on uniform drag for the macroscopic flow field. In future, the focus will be put on extending this multi-scale CFD method to the optimization design and reaction characteristics of MTO fluidized bed.
    Simulation and experimental study of fluid flow in the bed of columnar particles in a tubular fixed bed reactor
    Zirui ZHU Xuedong LIU Liangxiong JIANG Yutong GU Tao PENG Junjie YIN Meihua LIU Wei JIANG
    The Chinese Journal of Process Engineering. 2021, 21(9):  1022-1032.  DOI: 10.12034/j.issn.1009-606X.220288
    Asbtract ( )   PDF (4564KB) ( )  
    Related Articles | Metrics
    In view of the large number and large scale of tube bundles in the tubular fixed bed reactor, a single tube bundle was selected as the characteristic structure of the study. For the tube bundles filled with columnar particles of different diameters, the method of program coordinate positioning was adopted and the physical model of the columnar particle bed was established. DEM and CFD numerical simulation methods were used to explore the influence of the ratio of the inner diameter of the reaction tube to the equivalent surface area spherical equivalent diameter of columnar particles (Di/dp) on the fluid flow in the cylindrical particle bed. A single-tube fixed-bed reactor test device was established, and the differential pressure test method was used for experimental research. The results showed that when Di/dp increased from 5.37 to 12.75, the porosity of the bed and the uniformity of fluid distribution were improved, and the influence of the wall effect was weakened from the center of the bed to the tube wall. Based on the numerical simulation and experimental results, the bed pressure drop Ergun formula was corrected with constant coefficients for the columnar particle bed with Di/dp=12.75. The CFD simulation calculation results were in good agreement with the fitting formula. The research results provided guidance value for the design and application of fixed bed reactor.
    Influence of heat transfer coefficient of laminar cooling on metal materials temperature field
    Demin CHEN Yinghui LIU Biao LU Kai TANG Suojun WANG Guang CHEN
    The Chinese Journal of Process Engineering. 2021, 21(9):  1033-1041.  DOI: 10.12034/j.issn.1009-606X.220250
    Asbtract ( )   PDF (1035KB) ( )  
    Related Articles | Metrics
    The cooling intensity of laminar cooling determines the microstructure of metal materials, thus affecting the performance of the product, while the heat transfer coefficient directly affects the cooling intensity. In this work, a method for obtaining the heat transfer coefficient of laminar cooling is presented. Through the process analysis, the distribution form of the heat transfer coefficient was a piecewise function which was composed of half wave sine and straight line with the nozzle as the center. The characteristic parameters of the piecewise function can be achieved by some calculations, which involved the structural parameters, operational parameters and experimental data. The experimental bench verified the accuracy of this method. The calculation results showed that when the amplitude is increased by 1 W/(m2?K), the relative decline of the metal material surface temperature reached maximum in the final area, which was -0.36 m2?K2/W, and the maximum relative change of section temperature difference was 0.07 m2?K2/W. When the period decreased by 1 s, the relative increment of surface temperature of metal materials reached the maximum value of 13.24 K/s in the last region, and the section temperature difference showed periodic changes with a range of -2.5~0 K/s.
    Analysis on gas-phase flow characteristics in multi-spiral gas-liquid vortex separator
    Peng ZUO Xiuying YAO Chunxi LU
    The Chinese Journal of Process Engineering. 2021, 21(9):  1042-1053.  DOI: 10.12034/j.issn.1009-606X.220277
    Asbtract ( )   PDF (2696KB) ( )  
    Related Articles | Metrics
    In the Fischer-Tropsch synthesis process, light oil with high temperature is cooled to light oil droplets and non-condensing gas. Gas-liquid (or gas-droplet) separation and operation stability are directly related to both the stability and long period running of production process. Due to its structural complexity, fluid short circuit and wax jams, Fischer-Tropsch cycle heat exchanger is difficult to meet the industrial requirements. Hence, a multi-spiral gas-liquid vortex separator with simple structure, low pressure drop and big separation capacity was designed by drawing the super-vortex quick separator from gas-solids system. The CFD method was used to study the gas-phase flow field distribution characteristics in the MSGLVS. According to its structural characteristics and pressure distribution, the separator was divided into feed pipe zone, spiral arm zone, annular zone and separation zone. The simulation results showed that more than 60% of the total resistance loss of gas flow existed in the spiral arm. Discharged from the spiral arm, the gas was separated into three streams. One was upward counterclockwise gas along closure cover, another was corresponding downward gas and the others was upward clockwise gas in the region between spiral arm and feed pipe. Transverse vortices with zero axial velocity increased the pressure drop and liquid entrainment in the annular zone. The maximum tangential and axial gas velocities were kept at |r/R|=0.972 in the annular zone and the rotation angle of upward-flowing gas was always at 37.43° relative to the vertical direction, which demonstrated the good stability of separator. In the separation zone, there was a clear interface between upward and downward axial velocities. The tangential velocity conformed to the distribution of Rankine vortex along the radial direction, which was beneficial to the separation between gas and liquid phases. All tangential and axial velocities at different positions had a good linear relationship with the inlet gas velocity. The tangential velocities at |r/R|=0.893 (in the spiral arm zone) and 0.972 (in the annulus zone ) were most sensitive to inlet gas velocity.
    Effects of expanded graphite and carbon nanotubes on fire spread characteristics of PMMA
    Ke LIU Ying ZHANG Wei ZHANG Shuxian WU Wenyan PAN
    The Chinese Journal of Process Engineering. 2021, 21(9):  1054-1063.  DOI: 10.12034/j.issn.1009-606X.220259
    Asbtract ( )   PDF (978KB) ( )  
    Related Articles | Metrics
    Nine types of PMMA composite flame retardant materials were prepared by the melt blending method, and small-scale horizontal fire spread experiments were conducted on them. The effects of flame retardants of expandable graphite (EG) and carbon nanotube (CNTs) on the combustion characteristics of materials were compared and analyzed. The change rules of fire propagation characteristics parameters, such as fire propagation velocity, flame morphology, solid phase temperature and mass loss rate, were mainly studied. The results showed that EG mainly exhibited flame-retardant effect. With the increase of EG content, the fire propagation velocity, mass loss rate and surface heat flux of the composite material all decreased. CNTs exhibited a compound effect of antagonistic and synergistic flame retardancy. When the content of EG was low, the addition of 1% CNTs accelerated the fire spreading rate. Subsequently, with the increase of EG content, its antagonistic effect gradually disappeared, and finally showed the synergistic flame-retardant effect. The high thermal conductivity of CNTs and the "wick effect" promote combustion, and EG/CNTs system prevented combustion.There was a competitive relationship between them. After adding EG and CNTs, the fire spreading process showed obviously different combustion behavior. Before adding flame retardant, PMMA produced molten drips and accumulate into a pool fire, showing obvious burning characteristics of thermoplastic materials; adding EG and CNTs, a carbon layer formed, showing obvious burning characteristics of carbonizable materials.
    Process & Technology
    Leaching of valuable metals from nickel sulfide ores by mechanical activation
    Xiaohong ZHENG Weiguang LÜ Hongbin CAO Nan CAI Jin ZHAN Qingchun LI Fei KANG Zhi SUN
    The Chinese Journal of Process Engineering. 2021, 21(9):  1064-1073.  DOI: 10.12034/j.issn.1009-606X.220146
    Asbtract ( )   PDF (3050KB) ( )  
    Related Articles | Metrics
    The demand for nickel resources has increased significantly in recent years due to the large-scale application of high-nickel ternary lithium batteries in the field of new energy electric vehicles. To alleviate the shortage of nickel resources in China, the nickel extraction from nickel-containing minerals has received widely attention. As an important nickel-containing minerals, the composition of nickel sulfide ore is complex and it is difficult to be leaching under atmospheric conditions. Therefore, green, high efficient, and low-cost technologies for extracting nickel from nickel sulfide ore resources have attracted much attention. In this work, the mechanical activation was introduced to increase the reactivity of nickel sulfide ore, then Na2S2O8 was used to leaching activated nickel sulfide ore under atmospheric conditions. Various conditions including rotation speed, ball-to-material ratio and ball milling time as well as the acid concentration, oxidation concentration, leaching time, liquid-to-solid ratio, stirring rate and temperature in the leaching process were optimized and the mechanism was further discussed. It was found that the mechanical activation process reduced the particle size and increased the degree of amorphization of nickel sulfide ore resulting in an increase in its reactivity, and the leaching process converted part of the S2- to sulfur by Na2S2O8 reducing the release of harmful gas H2S during the reaction. At the optimal conditions (rotation speed of 613 r/min, ball-to-material ratio of 20:1, ball milling time of 120 min, acid concentration of 2 mol/L, Na2S2O8 concentration of 0.42 mol/L, leaching time of 60 min, liquid-to-solid ratio of 5:1, stirring rate of 400 r/min and temperature of 80℃), leaching rate of Ni, Co, Cu and Fe were 98.9%, 97.7%, 98.2% and 98.7%, respectively, while the content of Ni, Co and Cu in residues were 0.45%, 0.03% and 0.14%, respectively. With this research, it was expected to provide theoretical and technical support for the efficient extraction of valuable metals from nickel sulfide ores.
    Materials Engineering
    Preparation of UiO-66 based catalyst and its performance for CO methanation
    Yong YANG Yong XU Guangjin ZHANG
    The Chinese Journal of Process Engineering. 2021, 21(9):  1074-1081.  DOI: 10.12034/j.issn.1009-606X.220314
    Asbtract ( )   PDF (2432KB) ( )  
    Related Articles | Metrics
    Converting coal-based gas to natural gas has great economic and environmental benefits. As coal gasification technology matures, the CO methanation process acts as an important role. MOFs materials have shown excellent performance in many fields and have attracted more and more attention. Compared with conventional catalysts, UiO-66 is a Zr-based MOFs material with high specific surface area and good thermal and chemical stability, the active metal Ni has low cost and is equivalent to the catalytic hydrogenation ability of precious metals. In present study, a series of UiO-66 catalysts with Ni loading were prepared via ultrasonic impregnation method. Plenty of characterizations including XRD, BET, TG, SEM, TEM and XPS were used to study the structure, textual properties, thermal stability and morphology of the UiO-66 supported Ni-based catalysts. The catalytic performance of different catalysts was also evaluated in the fixed-bed reactor. The results showed that the Ni was reduced to metallic state in the prepared catalyst, the Ni metal was highly dispersed on the UiO-66 support and exhibited no significant effect on the framework structure and crystal morphology of the MOF material. The structure of the carrier did not change below 400℃. In the CO methanation reaction, the activation temperature of the Ni/UiO-66 catalysts gradually decreased with the increase of Ni loading content. At the same reaction temperature (320℃), the Ni content on different catalysts increased from 10% to 30%, the CO conversion increased from 10.7% to 89.7%.When the Ni content was 20%, the catalyst showed good stability during the reaction process. Meanwhile, the CO conversion on the Ni-based catalyst was much higher than that of the Fe-based and Co-based catalysts with the same metal content, indicating that Ni as an active metal had excellent catalytic performance in the synthesis gas to methane reaction process.
    Preparation of styrene acrylic resin composite with high thermal conductivity
    Fuhua JIA Bin GONG Qianyu WANG Duoyin ZHU Yanbin CUI
    The Chinese Journal of Process Engineering. 2021, 21(9):  1082-1090.  DOI: 10.12034/j.issn.1009-606X.220263
    Asbtract ( )   PDF (11921KB) ( )  
    Related Articles | Metrics
    Styrene acrylic resin is the main component of toner. The thermal conductivity of toner could be improved significantly by increasing the thermal conductivity of styrene acrylic resin. Then, the life of printer and copier could be extended. By adding single or hybrid high thermal conductivity fillers of carbon nanotubes and graphene into styrene acrylic resin, a connected thermal conductivity network was constructed in styrene acrylic resin to improve the thermal conductivity. When 0.75wt% multi-walled carbon nanotubes (MWCNTs) were added into styrene acrylic resin, the thermal conductivity of styrene acrylic resin composite was increased from 0.1252 W/(m?K) to 0.1644 W/(m?K) with an increasing of 31.31%. When 1.0wt% MWCNTs-COOH was added into styrene acrylic resin, the thermal conductivity of styrene acrylic resin composites was increased to 0.1751 W/(m?K) with an increasing of 39.86%. When MWCNTs-COOH and graphene were added into styrene acrylic resin, the thermal conductivity of styrene acrylic resin composites was increased to 0.2093 W/(m?K) with increasing of 67.17%, which indicated the hybrid fillers (MWCNTs-COOH and graphene) formed connected thermal conductivity network in styrene acrylic resin. Thus, the thermal conductivity of styrene acrylic resin composite was improved significantly.
    Preparation of MgMn2O4 cathode material for aqueous magnesium ion batteries
    Wanquan LI Doudou ZHANG Shuqing DENG Mengting YUAN Yunlan CHANG Bing QIAN Yaxin SUN
    The Chinese Journal of Process Engineering. 2021, 21(9):  1091-1098.  DOI: 10.12034/j.issn.1009-606X.220218
    Asbtract ( )   PDF (1936KB) ( )  
    Related Articles | Metrics
    Rechargeable magnesium ion batteries (MIB) as next-generation secondary battery systems have attracted increasing attention due to the high theoretical volumetric capacities, low cost and safety of Mg metal anodes. One of the key challenges in MIB is to develop cathode materials with higher specific capacity. Tetragonal spinel structure MgMn2O4 can be as MIB cathode material in aqueous electrolyte environments. However,the strong polarization and low kinetics diffusion of Mg2+ ion results a sluggish Mg migration in MgMn2O4. Herein, nanostructured MgMn2O4 samples were prepared via a simple sol-gel route followed by annealing using magnesium nitrate, manganese nitrate and critic acid as raw materials. The crystal structures and the morphologies of the products were analyzed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Electrochemical measurements of the products were carried out in a three-electrode breaker cell. The results showed that the samples annealed at 550℃ (MMO550) exhibited the maximum discharge specific capacity of 54.0 mAh/g at a current density of 40 mA/g, which was almost twice that of 750℃ samples (MMO750). The average grain size of MMO550 was about 30 nm analyzed by XRD and TEM, respectively. The MMO550 samples comprise microaggregated with channels and pores on the surface observed by FESEM, which were favorable for the effective contact between the electrolyte and particles. Further, nanocomposites of MgMn2O4 and carbon nanotube (MMO/CNT) obtained by annealing MMO550 with adding 5wt% CNT at a temperature of 400℃ for 2 h, exhibited the first discharge specific capacity of 118.0 mAh/g and capacity retention of 75% after 30 cycles. The Coulombic efficiency of MMO/CNT was very stable and above 95%. This outcome could be attributed to the improvement of conductivity provided by CNTs. FESEM and TEM results confirmed that CNTs can be acted as conductive grid connecting the MgMn2O4 particles effectively.
    DFT calculation on oxidation of polyphenylene sulfide by NO2 and SO3
    Zihang LI Yongfa DIAO Li'an ZHANG Fashan ZHOU Yao LU
    The Chinese Journal of Process Engineering. 2021, 21(9):  1099-1107.  DOI: 10.12034/j.issn.1009-606X.220285
    Asbtract ( )   PDF (1625KB) ( )  
    Related Articles | Metrics
    Through the B3LYP-D3/6-31G(d,p) method of density functional theory (DFT) and using intrinsic reaction coordinate (IRC) to confirm its connected reactants and products, the reaction paths of polyphenylene sulfide (PPS) oxidation were explored by looking for the transition state of sulfoxide and sulfone structure from PPS oxidized by NO2 and SO3. The change of the geometric structure and charge of the middle molecule revealed the microscopic mechanism of NO2 and SO3 oxidation PPS filter material. It showed that part of the electrons were attracted by the benzene ring and O atom when oxidizing S atom, which weakened the bond orders of the C-S bond and made it easier to break. It also increased the aromaticity of the benzene ring, making it easier to undergo substitution reactions and be attacked by free radicals. On this basis, the free energy barriers during the PPS oxidation process at different temperatures were further calculated. The ability of NO2 and SO3 to oxidize PPS was quantitatively compared by the reaction rate constant. Finally, the difficulty of the reactions were compared by calculating the half-life. The calculation results showed that the oxidation ability of SO3 to the S atom in the PPS molecular chain was stronger than that of NO2; in the actual environment, NO2 may not directly oxidize PPS, there were additional reaction paths; the half-life of sulfoxide formation was less than 2.5 h and the half-life of sulfone formation was less than 20 days when sulfur trioxide was less than 5 mol/L, therefore SO3 had a strong oxidizing effect on PPS, and the concentration of SO3 need to be strictly controlled in the environment using PPS.
    Environment & Energy
    Effect of moisture content and temperature on Chinese medicine residue pyrolysis characteristics
    Guanyi CHEN Xuhui QIU Qianqian GUO Jian LI Bin LIU Zeng DAN Beibei YAN Lei DONG Zhaoling ZHANG
    The Chinese Journal of Process Engineering. 2021, 21(9):  1108-1116.  DOI: 10.12034/j.issn.1009-606X.220193
    Asbtract ( )   PDF (3173KB) ( )  
    Related Articles | Metrics
    It is very important to develop a clean treatment for Chinese medicine residue. In this study, Chinese medicine residue pyrolysis characteristics were investigated by pyrolysis in lab-scale fixed bed with thermo-gravimetric analyzer. The influence of moisture content and pyrolysis temperature on products distribution and their components and characteristics, as well as the distribution rule of N element in gas phase, liquid phase and solid phase were studied in detail. The results showed that the Chinese medicine residue used in this study was completely pyrolyzed in 650~850℃. Increasing the temperature in this range was beneficial to the pyrolysis process and improved the pyrolysis efficiency and the quality of combustible gas. Decreasing the nitrogen content in gas product and pyrolysis char while the content in pyrolysis oil increased. Reducing the moisture content can improve the pyrolysis efficiency. It caused the content of nitrogen compounds in the pyrolysis oil increased and promotes the migration of nitrogen elements to the liquid phase. During the drying of traditional Chinese medicine residues, the content of alkali metals was reduced, which affected the composition of pyrolysis oil. Increasing the pyrolysis rate can also affect the pyrolysis product composition and nitrogen distribution to a certain extent. This study could provide a theoretical basis for the development of pyrolysis technology of Chinese medicinal residues.