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Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Forced oxidation of calcium sulfite and the influence of impurities in wet desulfurization by calcium carbide slag Yuewu ZHENG Ziheng MENG Lingxian LIAN Jiliang HAN Liwen ZHAO Xingguo WANG Gang XING Ganyu ZHU Huiquan LI The Chinese Journal of Process Engineering    2023, 23 (12): 1725-1738.   DOI: 10.12034/j.issn.1009-606X.223048 Abstract （186）   HTML （3）    PDF （9117KB）（114）       Knowledge map    Save The main component of calcium carbide slag (CCS) is calcium hydroxide [Ca(OH)2], which can replace limestone ore for wet flue gas desulfurization, but the desulfurization byproducts of calcium sulfite particles are small because of the strong alkalinity of CCS, which may affect the oxidation of calcium sulfite and the crystallization of calcium sulfate (CaSO4). The effects of different process conditions on particle size, oxidation rate, water content, and microcosmic appearance in the process of calcium sulfate oxidation and gypsum crystallization were systematically investigated, and the optimal process condition (calcium sulfate content of 5 g/L, aeration rate of 400 mL/min, initial pH value of 5.5, reaction temperature of 40℃, and reaction time of 4 h) was obtained. The byproduct of desulfurization gypsum (mainly calcium sulfate dihydrate) with large particle size, low water content, high purity, and uniform appearance was obtained under the optimal condition, which is conducive to the subsequent resource utilization of desulfurization gypsum. The leaching sequence of each element in the CCS under the actual operating pH conditions of the CCS slurry (acidic conditions) is Na>Ca>Mg>Si>Fe>Al. The effects of impurities of Na, Mg, Si, Fe, and Al in the CCS on the oxidation process of calcium sulfate and the crystallization of calcium sulfate were investigated under the above optimal reaction condition. The results indicated that Mg, Si, and Fe in the CCS had a significant promotion effect on the oxidation rate of calcium sulfate, while Al and Na in the CCS inhibited the oxidation of calcium sulfate. At the same time, the addition of Si impurity had almost no effect on the crystallization of calcium sulfate, the addition of the impurities of Mg, Fe, and Na had less effect on the crystallization of calcium sulfate, and the addition of Al impurity had a significant adverse effect on the crystallization of calcium sulfate. In this study, the CCS-based calcium sulfate was used as the raw material, and the study of calcium sulfate oxidation and gypsum crystallization was carried out, providing theoretical guidance for the forced oxidation process in the actual industrial desulfurization. Related Articles | Metrics Select Preparation of nano-calcium carbonate intensified by CO 2 micro bubble and transfer-reaction analysis Liheng WANG Xiaoping GUAN Ning YANG Zuze MU The Chinese Journal of Process Engineering    2023, 23 (9): 1313-1324.   DOI: 10.12034/j.issn.1009-606X.222450 Abstract （183）   HTML （3）    PDF （2491KB）（98）       Knowledge map    Save Carbonization is one of the common methods to prepare nano calcium carbonate. Controlling the particle size and particle size distribution of calcium carbonate is the key to the preparation of high-quality nano-calcium carbonate by carbonization. Different operating conditions have different effects on the reaction products. The particle size and size distribution of calcium carbonate can be effectively controlled by controlling different reaction conditions to improve the mass transfer and reaction conditions in the slurry. In batch-operated bubble column reactor, gas flow rate and bubble size are factors affecting mass transfer. This study investigates the influences of operation condition (gas flow rate, initial slurry condition), bubble type (ordinary bubble, micro bubble) on carbonation reaction rate and particle size distribution of calcium carbonate. Furthermore, the effects of bubble type on the stable region and abrupt change region in carbonation reaction process are analyzed. The experimental results show that when using ordinary bubble, the increase of CO2 flow rate accelerates the reaction process and reduces the particle size of calcium carbonate, but it does not affect the time of abrupt change region. With increasing the slurry concentration, the particle size first decreases and then increases in small-diameter column with ordinary bubble. However, when using micro bubble, the particle size of calcium carbonate is significantly reduced, and the time of abrupt change region decreases with the increase of gas flow rate. Moreover, the CO2 flow rate is no longer an influential factor on calcium carbonate particle size, which means that the gas-liquid mass transfer process is not the rate controlling step of carbonation reaction. This study provides some references for studying the application of micro bubbles in calcium carbonate crystallization. Related Articles | Metrics Select Gas-liquid flow simulation of a distillation tray based on OpenFOAM Xiaoqing ZHOU Yunpeng JIAO Tianbo FAN Xianfeng HE Jianhua CHEN The Chinese Journal of Process Engineering    2023, 23 (6): 858-869.   DOI: 10.12034/j.issn.1009-606X.222258 Abstract （181）   HTML （2）    PDF （8891KB）（175）       Knowledge map    Save Distillation column with sieve tray is an important separation equipment and widely used in the process industry. The complex behavior of the gas-liquid two-phase flow in distillation columns, especially on the tray, significantly affects the separation performance. With increasing applications of the CFD simulation in multiphase flow, it is interesting to adopt the CFD tools in distillation design and optimization. Traditionally, commercial CFD software has been applied in this field, while they face the problems of black-box feature, limited and expensive license, inflexibility of developing tailored models, etc. Therefore, this work turns to the open source platform of OpenFOAM. By using the Eulerian solver in OpenFOAM, an experimental sieve tray column is studied. The two-phase flow characteristics under different operating conditions are explored, including the height of the clear liquid layer, the gas and liquid velocity, the pressure drop, etc. The predicted trends are consistent with the experimental results. The simulated clear liquid height decreases with increasing gas flow rate and increases with liquid flow rate, and its deviation from the experiments is attributed to the empirical drag correlations which need further study. The influences of sieve holes and liquid inlet conditions on the liquid velocity distribution have been studied. It is found that the number of sieve holes has little impact, and simulations with non-uniform liquid inlet conditions agree with the experiments better. This study verifies the feasibility of using OpenFOAM to simulate distillation columns. The next step is to apply the mesoscale approach to gas-liquid crossing flow systems, construct a new interphase drag model to improve the accuracy of the simulation, and consider the influence of heat and mass transfer on the flow field. This work lays a foundation for the next-step coupling simulations, which is promising for the design and optimization of distillation columns. Related Articles | Metrics Select The controllable preparation of SiO 2 microspheres by Stöber method in the microreactor Yangping YU Mei YANG Mingzhi LI Guangwen CHEN The Chinese Journal of Process Engineering    2023, 23 (6): 908-917.   DOI: 10.12034/j.issn.1009-606X.222290 Abstract （175）   HTML （3）    PDF （41018KB）（75）       Knowledge map    Save SiO2 microspheres were synthesized in a controlled manner via St?ber method by using a microreactor and a batch reactor in series to achieve rapid mixing of the reactant and flexible adjustment of the aging time. The phase and morphology of the as-prepared SiO2 were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscope (TEM). The results showed that the mean particle size and dispersity of the SiO2 microspheres depended on the competition between the tetraethyl orthosilicate (TEOS) hydrolysis reaction and the silanol monomer condensation reaction, and were also significantly influenced by the mixing rate of reactants in the initial period. The monomer addition model was employed to explain the experimental results. When the aging temperature increased from 25℃ to 75℃, the mean particle size of SiO2 microspheres decreased from 472 nm to 200 nm, with little change in dispersity. Because the reaction rates of TEOS hydrolysis and silanol monomer condensation increased with the increasing aging temperature, the supersaturation degree of silanol monomer immediately exceeded the critical supersaturation for homogeneous nucleation at higher aging temperatures. A large number of nuclei was formed, causing the formation of smaller microspheres. When the concentration of aqueous ammonia was increased from 0.8 mol/L to 5.6 mol/L, the mean particle size of SiO2 microspheres increased from 34 nm to 261 nm, and the dispersity became better. At higher ammonia concentration, more ethoxyl groups were hydrolyzed in a single TEOS molecule to produce silanol monomers with more silanol groups. This kind of silanol monomers could condense into siloxane networks at a faster rate, leading to larger particle sizes. When the water concentration increased to 35.6 mol/L or the TEOS concentration increased to 1.0 mol/L, multiple nucleation or continuous nucleation occurred in the solution, resulting in a dramatic deterioration of the dispersity of SiO2 microspheres. Increasing the Reynolds number (Re) or reducing the channel inner diameter led to the formation of monodisperse SiO2 microspheres, which could be attributed to the faster mixing between the reactants. Related Articles | Metrics Select DEM modeling of resonant motion of particles inside moving bed Qinjian SHEN Shijie DONG Dancheng ZHANG Hui GUO Yinling SONG Xiaoxing LIU The Chinese Journal of Process Engineering    2023, 23 (6): 826-836.   DOI: 10.12034/j.issn.1009-606X.222161 Abstract （166）   HTML （5）    PDF （5476KB）（146）       Knowledge map    Save Moving beds are ubiquitous in various process industries. Thoroughly understanding and accurately characterizing the complex flow behavior of granular materials from the component particle scale is obviously of great significance for the design, scale-up, and optimization of moving beds. In this work, the flow behavior of granular assemblies in moving beds under both the funnel flow and semi-mass flow discharge regimes are investigated by performing three-dimensional discrete element method (DEM) simulations, with a focus on the possible similarities and differences between the fluctuating characteristics and also the corresponding underlying mechanisms of the transient motions of particles under these two discharging conditions. The reliability of the DEM simulation is verified by comparing the predicted evolutions of the boundary of the flowing zone and also its characteristic width with experimental results. The simulation results demonstrate that under both discharge conditions, the temporal variations of the spatially averaged axial velocity of particles in the upper part of the flowing zone present notable non-random fluctuating characteristics, manifested by the appearance of a clear peak in the Fourier spectrum of the time series of spatially averaged particle axial velocity. The spatial correlation analysis results show that the temporal fluctuations of the spatially averaged axial velocity of particles in different axial regions of the upper part of the flowing zone are closely correlated, suggesting the occurrences of resonance under both discharging types. The delayed correlation analyses of the time series of the spatially averaged axial velocities of particles in different axial zones indicate that such resonant behavior originates from a bottom zone right above the outlet. The delayed correlation analyses of the time series of the spatially averaged particle axial velocity and the spatially averaged particle contact force demonstrate that there exists a strong correlation between the temporal fluctuations of these two parameters, and the latter precedes the former, which hints that the observed resonance could be ascribed to the free-fall arch mechanism. In brief, the presented simulation results clearly demonstrate that resonance can occur during both funnel and semi-mass flow discharges and there is no intrinsic difference between the resonant features of particles under these two discharging conditions. Related Articles | Metrics Select Numerical study on CO 2 bubble rise process coupled with mass transfer Donghao PEI Lexiang ZENG Mengdie GAO Jincheng RUAN Jun CAO The Chinese Journal of Process Engineering    2023, 23 (9): 1244-1255.   DOI: 10.12034/j.issn.1009-606X.222385 Abstract （156）   HTML （5）    PDF （15818KB）（122）       Knowledge map    Save Gas-liquid two-phase flow and mass transfer phenomena widely exist in nature and daily life. Studying the mass transfer process of bubbles in water is of great significance for understanding the mass transfer mechanism and exploring the enhancement of the mass transfer process. The volume of fluid (VOF) method was used to simulate the rising process of CO2 bubble in still water, and the mass transfer process was considered by a user defined function program. The instantaneous velocity, mass transfer coefficient, CO2 dissolved amount, and mass transfer wake changes of bubbles with different initial diameters during the rising process were studied. In the process of bubble rising, the transverse velocity changed periodically and the oscillation amplitude decreased with the increase of bubble initial diameter, while the longitudinal velocity increased with the increase of the bubble initial diameter. Between 3.5 mm and 6 mm, with the increase of the bubble diameter, the CO2 dissolved amount increased, and the wake stream showed three states: symmetrical state, transitional state, and periodic shedding. The critical Re number of 3.5~6 mm bubble wake transition increased with the increase of bubble initial diameter, the frequency of wake periodic shedding was 17~22 Hz, and the departure frequency decreased with the increase of bubble initial diameter. The bubble wake was consistent with the mass transfer wake. With the increase of the bubble initial diameter, the influence range of the bubble mass transfer wake increased. Related Articles | Metrics Select Study on performance of forced circulating water electrolytic cell coupled with electrochemistry and multiphase flow model Xudong DUAN Simin WANG Jian WEN The Chinese Journal of Process Engineering    2023, 23 (6): 880-888.   DOI: 10.12034/j.issn.1009-606X.222318 Abstract （145）   HTML （5）    PDF （10405KB）（100）       Knowledge map    Save Hydrogen production from electrolytic water technology is an important way to solve the future energy crisis and realize green development. Among them, alkaline electrolytic water has simple structure and low cost, which is suitable for large-scale development. The concentration polarization caused by the bubble behavior in the alkaline electrolytic cell has a great impact on the performance of the electrolytic cell, reducing the contact area between the electrode and the electrolyte and increasing the resistance and the energy consumption of hydrogen production from electrolytic water. But most of the numerical simulation studies on electrolytic water do not consider the impact of the flow behavior of gas-phase products. In this work, the electrochemical model is coupled with the gas-liquid two-phase flow model, the drag force, lift force and bubble dispersion force are included in the equation describing the gas-phase volume force, and the influence of concentration polarization is considered. The gas production process of the forced circulation alkaline electrolytic cell is simulated, and the calculation results are more in line with the real flow state. The influence of operating conditions on the performance of the electrolytic cell is further studied. It is calculated that with the increase of electrolyte temperature from 60℃ to 80℃, the average current density increases by 3.84%, and the uniformity of current density distribution deteriorates. When the electrolyte flow rate is increased from 0.10 m/s to 0.30 m/s, the average current density and distribution uniformity can be improved simultaneously, and the average current density is increased by 0.64%. With the increase of potassium hydroxide concentration from 1 mol/L to 6 mol/L, the current density increases by 40.21%, but the uniformity of current density distribution deteriorates. And among the three operating variables, the electrolytic performance is the most sensitive to the concentration of potassium hydroxide in electrolyte. This work provides guidance for the internal mechanism research and operation parameter design of electrolytic water. Related Articles | Metrics Select Effect of conical distribution plate with slit hole on flow characteristics in fluidized reactor Tiancheng WANG Gong CHEN Dexi WANG Lixin SHAO The Chinese Journal of Process Engineering    2023, 23 (10): 1390-1400.   DOI: 10.12034/j.issn.1009-606X.222472 Abstract （142）   HTML （5）    PDF （1471KB）（103）       Knowledge map    Save Water pollution has gradually become one of the prominent problems restricting the harmonious development of urban ecosystem. At present, the development of efficient wastewater treatment technology has important practical significance to alleviate this problem. Wastewater treatment reactor is the core equipment of wastewater treatment, and the internal flow characteristics affected by its structure have an important impact on water treatment efficiency. Fluidization reactor has become a common sewage treatment equipment because of its high heat and mass transfer rate. In view of the liquid phase back mixing and uneven liquid-solid mixing still exist in fluidized reactor for wastewater treatment. Based on the mobile biofilm wastewater treatment technology and the concept of maximizing the space utilization of integrated wastewater treatment equipment, a rectangular fluidized reactor with slit hole conical distribution plate was designed. The orifice area of the distribution plate gradually increased from the center of the reactor to the outside, and the Euler-Euler multiphase flow model and RNG k-ε turbulence model were used for numerical simulation of the fluidized reactor with a conical distribution plate with slit holes. The effect of the distribution plate structure on the distribution of particles in the reactor was studied by the arrangement of the holes and the cone angle of the slit hole conical distribution plate. The results showed that the conical distribution plate with slit holes can solve the problems of liquid-phase backmixing and uneven liquid-solid mixing, form multiple ring core flows in the reactor, improve the uniformity of particle distribution, and strengthen the liquid-solid mixing. Based on the comprehensive evaluation of particle volume fraction, flow rate, and bed density standard difference, the optimal hole distribution mode of the slit conical distribution plate was determined to be perpendicular to the central axis, and the optimal fluidization effect of the reactor appeared under the cone angle of 120°. Related Articles | Metrics Select Effect of sintering time on microstructure evolution and magnetic properties of Fe-Si/SiO 2 soft magnetic cores Hui KONG Rui WANG Zhaoyang WU Yihai HE Haichuan WANG Nachuan JU The Chinese Journal of Process Engineering    2023, 23 (6): 898-907.   DOI: 10.12034/j.issn.1009-606X.222166 Abstract （137）   HTML （1）    PDF （51402KB）（58）       Knowledge map    Save Soft magnetic cores consist of a highly saturated ferromagnetic powder core and a high resistivity insulating shell, resulting in core-shell heterogeneous structure, and could therefore have high permeability, high saturation magnetization, high resistance, and low eddy current loss, which is the basis for limiting eddy current operation and reducing high-frequency losses during AC magnetization. Therefore, maintaining the integrity and homogeneity of the core-shell heterostructure within soft magnetic cores during the sintering molding process is critical for optimizing the magnetic properties. In this work, Fe-Si/SiO2 soft magnetic cores were prepared by hot-pressing sintering, and the evolution behavior of Fe-Si/SiO2 soft magnetic cores' core-shell heterostructure with sintering time and the influence on the magnetic properties were systematically studied. These obtained results showed that the Fe-Si/SiO2 soft magnetic core core-shell heterostructure tended to be more complete with the prolongation of the sintering time range from 3 min to 10 min, and the SiO2 insulating layer began to crystallize when the sintering time was up to 9 min. When the sintering time was greater than 11 min, the core-shell heterostructure began to collapse due to the overheating phenomenon caused by the superposition of two thermal effects in the gradient temperature field during the hot-pressing sintering process. Under the condition that the core-shell heterostructure remained intact and dense, the Fe-Si/SiO2 soft magnetic cores with a sintering time of 10 min exhibited the best magnetic properties among all 8 samples, the saturation magnetization was 220.9 emu/g, the resistivity was 0.72 mΩ?cm, and the total loss in 10 mT and 100 kHz was 627.5 kW/m3. Compared to the sample with destroyed core-shell heterostructures (13 min), the total loss decreased by about 38.7%, of which the eddy current loss decreased by about 33.1%, and the hysteresis loss decreased by about 14.7%. Related Articles | Metrics Select Numerical investigation of effects of bath flow on melting behavior of scrap Xiaobin ZHOU Yu TENG Wanxing WANG Qiang YUE Zhenghai ZHU The Chinese Journal of Process Engineering    2023, 23 (9): 1256-1267.   DOI: 10.12034/j.issn.1009-606X.222403 Abstract （133）   HTML （4）    PDF （24471KB）（84）       Knowledge map    Save Nowadays, more and more scrap is required to be added in the bath of the converter accompanied by the increasing requirements on the environment and increasing volume of available scrap in China. Consequently, the melting rate of the scrap would be significant if a large amount of scrap is added into the bath for the steelmaking process. The carbon content, temperature, and flow of the bath are the main factors that influence the scrap melting process in a bath of hot metal. The current study mainly focused on the effects of bath flow on the melting behavior based on a scrap melting process performed in the experiment in which the scrap melting behavior in a bath was investigated. Specifically, the effects of nature convection and driven convection on the meting process were investigated by applying a mathematical model. The results found that nature convection was formed in the vicinity of the melting interface when a scrap bar was immersed in the melting bath of hot metal. As a result, the heat transfer between bath and scrap can be enhanced by the flow at the melting interface. Also, the hot metal with high carbon content was driven to the melting interface. In turn, the melting rate was accelerated. The intensity of nature convection decreased when the initial temperature of the scrap was increased. The melting rate was remarkably increased when the driven convection was introduced to the bath. Compared to the initial temperature of 25℃ with a melting rate of 107 mm3/s, the melting rate was only 50 mm3/s when the initial temperature of scrap was 1000℃ at 5 s. In addition, when the melting was performed at 15 s, the rest volume of the scrap with the nature convection was 1054 mm3, which was 2.3 times for driven convection with the driven flow velocity of 0.15 m/s. Also, the melting rate of the scrap with the driven flow velocity of 0.15 m/s was about 1.8 times that of the nature convection at 10 s. Related Articles | Metrics Select Catalytic conversion of the by-product bromoethanol in the process of CO 2 cycloaddition Ruibin GAO Lixin YI Zifeng YANG Li DONG Yifan LIU Hongfan GUO Yunong LI The Chinese Journal of Process Engineering    2023, 23 (11): 1518-1529.   DOI: 10.12034/j.issn.1009-606X.222468 Abstract （133）   HTML （0）    PDF （1824KB）（134）       Knowledge map    Save The rapid and massive accumulation of greenhouse gas CO2 in the atmosphere directly leads to global warming, ecological damage, and other environmental problems. From the perspective of renewable carbon resource utilization, CO2 is a widespread, inexpensive, and easily available C1 resource. The synthesis of ethylene carbonate employing CO2 as raw material provides a feasible industrial scheme for CO2 utilization with the atomic economy. The traditional efficient catalyst for this cycloaddition is halogen ionic liquid. However, the loss of halogen ions in the cycloaddition process leads to the additional consumption of epoxide and the generation of halogenated alcohol, thus decreasing the selectivity and yield of the main product, resulting in separation difficulty and improving equipment requirements. Therefore, it is necessary to develop an ideal catalytic system to inhibit and transform the by-product of halogenated alcohols. In this work, a series of alkalescent ionic liquids had been designed and developed to realize the in?situ conversion of bromoethanol under the condition of cycloaddition (temperature of 130℃, CO2 pressure of 3 MPa, reaction time of 3 h). The effects of different reaction conditions and different alkaline ionic liquids on the conversion of bromoethanol were investigated, including ionic liquid type, reaction temperature, different pressure environment, reaction time, etc. The reaction law of bromoethanol conversion was revealed, among which [Bu4P][HCO3] showed optimal performance. Using gas atmosphere and solvent microenvironment to regulate different reaction paths, the conversion rate of bromoethanol reached 20%~50%. After ethylene carbonate (EC) addition, the by-products with bromine-containing covalent bonds were reduced, which was more conducive to the formation of bromine ions. The conversion of halogen covalent bonds to halogen ions restored part of the catalytic activity of the cycloaddition reaction system. This was a simple versatile approach, which can realize the in?situ regulation of bromoethanol conversion pathways in the CO2 cycloaddition system, and promote the optimization of the CO2 utilization system and the circulation of halogen ions, hence possessing important scientific significance and application value. Related Articles | Metrics Select Axial distribution characteristics of binary particles in a gas-solid fluidized bed Jun YAN Weixing JIN Yiping FAN Chenglin E Chunxi LU Fuwei SUN The Chinese Journal of Process Engineering    2023, 23 (6): 837-846.   DOI: 10.12034/j.issn.1009-606X.222204 Abstract （131）   HTML （5）    PDF （2638KB）（99）       Knowledge map    Save In order to achieve the goal of carbon peaking and carbon neutrality while taking into account the product yields of both gasoline and polyolefin, it is desirable to further optimize the polyolefin catalytic cracking technique by introducing two types of catalysts with distinct physical properties into the one reaction-regeneration system. Therefore, this work focuses on the flow and mixing characteristics of the binary particle system in a fluidized bed. The axial distribution of pressure in the binary particles fluidized bed was measured. The average solid concentration in the axial direction was investigated consequentially. The variation of the interface location between the dense phase and dilute phase zones was determined by analyzing the turning point of the axial profile of the differential pressure. An empirical coorelation was given based on the experimental results. Furthermore, the relationship of the fluidization performance of the binary particles in the fluidized bed to the gas velocity as well as the particle mixing ratio were discussed by investigating the standard deviation of pressure signal. The experimental results showed that the average particle concentration tended to decrease in the axial direction of the fluidized bed. The particle concentration decreased with an increasing of the superficial gas velocity in the dense-phase zone whereas it presented an increasing tendency in the dilute phase zone. The total average particle concentration in the dense-phase zone assumed a maximal value when the mixing ratio of big particle in the binary particles was 0.685. The interface height between the dense-phase and the dilute phase zones increased with an increasing of superficial gas velocity. It was also found that the fluidization performance and mixing degree of binary particles in the fluidized bed reached the best when 0.225≤xl≤0.479 and 0.561≤ug≤1.122 m/s. Related Articles | Metrics Select Effect of fluid-structure interaction on liquid water flow in gas diffusion layer at microscale Jiemin WANG Sai ZHANG Qingtai WANG Xianjun WANG The Chinese Journal of Process Engineering    2023, 23 (12): 1627-1636.   DOI: 10.12034/j.issn.1009-606X.223096 Abstract （127）   HTML （6）    PDF （1468KB）（65）       Knowledge map    Save This work presents a new method to reconstruct the microstructure of carbon fiber gas diffusion layer (GDL), which is used to study the effect of velocity field in rough channels on GDL seepage. The random distribution model of pore channels in the diffusion layer is obtained by using the rough element and fractal theory. By distinguishing the hydrophilicity/hydrophobicity of the channel wall, four parameters, namely, the dispersion velocity ratio, the slip enhancement coefficient, the viscosity enhancement coefficient, and the microscale effect enhancement coefficient, are obtained. With accurate internal velocity distribution reconstructed as a control factor, and the effective seepage coefficient model is obtained by combining Darcy's law. The flow process of liquid water in GDL duct is simulated, and the influence of different roughness and contact angle on liquid water transmission performance is analyzed. The results show that the distributions of dispersion velocity, viscosity and slip velocity in the diffusion layer are affected by the random distribution of channel roughness elements and the non-uniform fluid solid interaction, and the four control factors act together on the flow process of liquid water and promote the discharge of liquid water. Under the same roughness, when the contact angle is 0o~180o, the promotion of hydrophilic wall slip effect conteracting the inhibition of dispersion effect and viscosity increases, and the promotion of hydrophobic wall slip effect conteracting the inhibition of dispersion effect and viscosity decreases, and the slope of flow change curve increases significantly at first and then decreases gradually. The newly established effective seepage coefficient model of liquid water in the diffusion layer can accurately describe the flow law in GDL, which has certain guiding significance for the internal water management of GDL. Related Articles | Metrics Select Large eddy simulation for single particle wake characteristics in concave-wall tangential jet Jing ZHANG Wenhao HOU Chenghao ZHOU Zhiguo TIAN Bin GONG The Chinese Journal of Process Engineering    2023, 23 (11): 1497-1505.   DOI: 10.12034/j.issn.1009-606X.223019 Abstract （126）   HTML （4）    PDF （6139KB）（211）       Knowledge map    Save Large eddy simulation was used to simulate the influence of spherical particles near the wall on fluid flow characteristics under the action of tangential jets on the concave-wall. The simulated wake vortex results were in good agreement with the experimental tracer image. The vortex structure and its evolution process of particle wake with particle diameter dp=4 mm and radius of curvature of concave wall R=200 mm were studied. The changes of velocity, vorticity, and streamline around the particle were investigated at Reynolds number Re=700~10 000. The results showed that the vorticity in the influence area of particles increased, the peak value of vorticity always appeared on the upstream surface of particles, and the recirculation zone behind the particles shrank significantly with the increase of Reynolds number. When Re=700, there was only one wake vortex behind the particle along the concave wall jet spanwise. When Re≥2000, there were two wake vortices behind particles along the concave wall jet spanwise, and the tangential velocity and vorticity of the fluid fluctuated periodically. The particle lift and resistance were monitored. There was the vortex shedding frequency at Strouhal number St=0.000 854 when Re=2000, and the peak value of the lift power spectrum occurred at St=0.001 52. The frequency peak corresponding to the boundary layer and wake instability was not found in the drag power spectrum when Re=10 000, and the peak of the lift power spectrum occurred at St=0.008 74. The particle wake had a great influence on the flow field. The analysis of the particle wake characteristics in the tangential jet on the concave wall was an in-depth study of the liquid-solid two phase separation mechanism. It provided the theory for the characteristics of single particle wake vortex in the process of heterogeneous separation of the tangential jet from concave wall. Related Articles | Metrics Select Influence of structure of swirlers on fluid field characteristics of main absorption tower Zhanyu YANG Qiling YIN Tuanliang WANG Yuge LI Wenming SONG Yufu ZHANG Yuan YAN Liping WEI The Chinese Journal of Process Engineering    2023, 23 (10): 1401-1410.   DOI: 10.12034/j.issn.1009-606X.222384 Abstract （124）   HTML （3）    PDF （17878KB）（94）       Knowledge map    Save The main absorption tower of natural gas with high hydrogen sulfur content purification needs regular welding repair due to corrosion. Before and after repair, the internal combustion integral heat treatment technology can be used to perform hydrogen-eliminating treatment and eliminate stress. The arrangement of swirlers has an important impact on air distribution and flame control during the heat treatment. In this work, the fluid field characteristics of two-stage swirler, single-stage swirler I and II in the absorption tower are simulated, respectively. The results show that there is no obvious recirculation zone above the two-stage swirler and the velocity distribution is uniform. A large tangential velocity is generated above the inner and outer swirler blades. The maximum tangential velocity is 8.33 m/s when the inlet velocity is 9.8 m/s, followed by single-stage swirler II and single-stage swirler I, 4.5 m/s and 3.12 m/s, respectively. The pressure drop in the tower corresponding to the two-stage swirler has the smallest change. These prove that the two-stage swirler can effectively generate low resistance swirling flow field. The proportion of the streamline at the bottom of the tower corresponding to the two-stage swirler changes steadily with the gas mass flow rate, and is kept at about 14%, which is consistent with the percentage of the tower bottom wall in the total surface area of the tower body. It can ensure that enough gas media return to the tower bottom and promote gas convection. The 90% residence time of two-stage swirler increases linearly with the increase of gas mass flow rate. In general, the swirling effect of the two-stage swirler is better than that of the other two swirlers, and this study provides a reference for the optimization design of swirl device of internal combustion integral heat treatment process. Related Articles | Metrics Select Design of temperature control system for evaporator based on cascade fuzzy self-adaptive PID method Jun SUN Dian ZHANG Qingshan HUANG Liang TIAN Tianqi CHANG Qi LIU The Chinese Journal of Process Engineering    2023, 23 (9): 1290-1299.   DOI: 10.12034/j.issn.1009-606X.222320 Abstract （120）   HTML （11）    PDF （1561KB）（83）       Knowledge map    Save It has been widely accepted that applying the traditional control method is difficult to achieve precise temperature control of the evaporator because the evaporator temperature has nonlinear, time-varying characteristics with a significant lag. Based on the evaporator production process analysis, an evaporator temperature control method based on the cascade fuzzy adaptive proportional-integral-differential (PID) is proposed here, which combines the fuzzy control theory with the cascade PID control theory to set up a Continuous Function Charts (CFC) configuration of fuzzy adaptive PID control for the main loop and the secondary loop. A real-time self-adapting amendment of PID parameters in the main loop and the secondary loop during the evaporator temperature control can be realized using this control strategy. The experimental results with the SMPT-1000 simulation equipment and Siemens PCS7 process control system show that after the real-time self-adapting amendment of PID parameters, the computed new proportional parameter can successfully accelerate the response speed of the system, the calculated new integral parameter can efficiently reduce the deviation of the system, and the deduced new differential parameter can wisely play an essential role in the anticipatory control. The corresponding experimental results demonstrated that the adjustment time of temperature response could be shortened by one-half, and the maximum deviation could be reduced by more than four-fifths. Additionally, the adjustment time of the temperature rise load could be shrunk by more than three-fifths, and the maximum deviation could be decreased by more than four-fifths. Moreover, the recovery time for the superheated steam perturbation could be narrowed by more than one-half, and the deviation of minimum and maximum temperature could be condensed by more than one-tenth. It is noteworthy that compared with the traditional cascade PID control method, the cascade fuzzy self-adaptive PID control strategy proposed here has the notable advantages of short regulation time, slight overshoot, and good robustness, which can overcome the shortcomings of the traditional cascade PID control method and provide an effective way and mathematical models to solve the problem of accurate temperature control in the evaporator. Therefore, the control strategy developed here has a particular significance in ensuring the smooth operation of the evaporator. Related Articles | Metrics Select Flow characteristics of gas-liquid two-phase flow in microchannel with obstacles Yuanhao HUO Gang YANG Huichen ZHANG The Chinese Journal of Process Engineering    2023, 23 (12): 1617-1626.   DOI: 10.12034/j.issn.1009-606X.222454 Abstract （118）   HTML （9）    PDF （5399KB）（123）       Knowledge map    Save The obstacles in the microchannel have a significant impact on the pressure drop and bubble shape of gas-liquid two-phase flow. In this work, experimental and numerical simulation methods are used to explore the effect of obstacles in the channel on the movement characteristics of nitrogen/water gas-liquid two-phase flow in the microchannel. The variations of pressure drop and bubble length under different gas and liquid flow rates in microchannel with obstacles are analyzed. The results show that the pressure drop in the obstacle microchannel is higher than that in the barrier free microchannel, and the maximum pressure drop occurs with the obstacle in the center. Through numerical simulation analysis, this is due to the vortex generated after the obstacle, and the pressure drop is positively related to the vortex length. The bubble length of the obstacle microchannel changes within 25% compared to the barrier free channel, and the bubble length becomes shorter as the obstacle approaches the center. Under different flowing conditions, there are three phenomena when bubbles pass through obstacles, including retraction without rupture, retraction with rupture, and direct rupture without retraction. The retraction lengths increase with capillary number increasing in retraction without rupture. The retraction lengths reduce with capillary number increasing in retraction with rupture. When the retraction length decreases to 0, it become a direct fracture without retraction. The variation range of retraction length gradually increases as the obstacle approaches the center. When passing through all obstacles, different breaking and merging laws are displayed under different working conditions. By numerical simulation, different vortex lengths after the obstacle result in different pressure drops, and there exists sever change at the moment of bubble rupture. When passing through the obstacle, the change of bubble shape is affected by the change of liquid phase velocity around it, different velocities in the sub channels on both sides of the obstacle determine the different rules of the two sub bubbles after passing through the obstacle. Related Articles | Metrics Select Study on the thermal decomposition reaction behavior and kinetic characteristics of millimeter sized magnesite particles in fluidization Feng GAO Liangliang FU Dingrong BAI Guangwen XU The Chinese Journal of Process Engineering    2023, 23 (10): 1435-1445.   DOI: 10.12034/j.issn.1009-606X.222470 Abstract （116）   HTML （3）    PDF （5290KB）（76）       Knowledge map    Save Thermal decomposition is the primary step to utilizing magnesite resources. Traditionally, it has been done in the shaft or rotary-type kilns using lumpy bulk raw materials, leaving a substantial amount of small or millimeter-sized particle materials unusable. In this work, the decomposition of millimeter-scale magnesite particles using high-temperature gas-solid fluidized beds is proposed. The thermal decomposition behavior of magnesite particles with four different sizes in the range of 0.3~3 mm at different temperatures using a laboratory fluidized bed reactor of 30 mm in diameter combined with an online mass spectrometry analyzer is reported in this work. The results showed that the thermal decomposition rate of magnesite particles accelerated with the increase in bed temperature and the decrease in particle size. As the decomposition progresses, three characteristic stages can be observed. At the initial stage of decomposition corresponding to conversions of less than about 0.1, the reaction was controlled by the interfacial chemical reaction kinetics, and the apparent activation energy decreased with increasing particle size. In the middle stage of the reaction (the conversion was 0.1~0.9), the decomposition reaction obeyed the shrinking core model, and the activation energy of the decomposition reaction remained almost unchanged with the conversion for the particle of 0.46 mm in diameter but increased with the conversion for other large-sized particles. In the later stage of the thermal decomposition reaction (after the conversion was greater than 0.9), the conversion varied slowly with time, and the reaction was affected significantly by heat transfer and gas diffusion. For each of the decomposition reaction stages, the reaction mechanisms and kinetic parameters were determined based on the experimental data. This study discussed the effects of bed temperature and particle size on the thermal decomposition of magnesite particles for a better understanding of the thermal decomposition behavior of millimeter-sized magnesite particles in fluidized beds. The study provided essential data support for the development of new products for the preparation of magnesite particles in fluidized beds, serving as a critical reference for the preparation of millimeter-sized high-density dead burned magnesia at high-temperature in fluidized beds. Related Articles | Metrics Select Experiment and DEM numerical simulation of mixing power of ultrafine powder based on similarity theory Hui CHEN Xuedong LIU Wenming LIU Weiwen ZHENG Honghong ZHANG Kaixin LÜ The Chinese Journal of Process Engineering    2023, 23 (11): 1506-1517.   DOI: 10.12034/j.issn.1009-606X.222421 Abstract （116）   HTML （2）    PDF （2454KB）（122）       Knowledge map    Save In order to study the correlation between the stirring power characteristics of ultrafine powder and the operating parameters and the calculation expression of stirring power, the problems of difficult calculation and lengthy calculation time in ultrafine powder stirring simulation were solved. The method of combining experimental research and numerical simulation was used to study the variation law of stirring power and torque of the ultrafine powder mixing process in the mechanical powder mixer. The stirring experiment of light calcium carbonate powder with an average particle size of 10.56 μm was carried out, and the operating parameters in the mechanical powder mixer, including the effects of rotational speed, blade position, and material surface height on the stirring power and torque of ultrafine powder were studied, and the expression of power calculation was obtained. Using the similar principle, the fine particles of the powder were enlarged, and the virtual experiments were carried out on the enlarged coarse particles to obtain the contact parameters. The DEM numerical simulation of the coarse particle stirring process was carried out, and the results of the simulated stirring power and torque were compared with the experimental results. The results showed that the mixing power consumption of ultrafine powder in the mechanical powder mixer was closely related to the parameters of the rotational speed, blade position, material surface height and so on. At the same time, the torque value and power value were positively correlated with rotational speed and material surface height, and negatively correlated with the blade position. The ratios of simulated torque value and power value to experimental torque value and power value were basically consistent with the particle amplification factor, which verified the accuracy of the similar principle applied to study the influence of blade position and material surface height on the stirring power characteristics. Related Articles | Metrics Select Effect mechanism of calcium hydroxide on morphology of calcium sulfate hemihydrate in magnetized water Xingtong LIN Dashi LEI Yubin WANG Shuai ZHANG Liang LI Kaiqiang HUA The Chinese Journal of Process Engineering    2023, 23 (7): 1081-1088.   DOI: 10.12034/j.issn.1009-606X.222285 Abstract （115）   HTML （4）    PDF （2866KB）（66）       Knowledge map    Save To clarify the influence of calcium hydroxide on the morphology of calcium sulfate hemihydrate hydrothermal products in the magnetized water system, scanning electron microscopy (SEM), conductivity analysis, and X-ray diffraction (XRD) were used to characterize the calcium sulfate hemihydrate samples. On this basis, the effect mechanism of calcium hydroxide on hydrothermal products of calcium sulfate hemihydrate crystal morphology was clarified. The results revealed that calcium hydroxide with different concentrations had an extremely significant regulatory effect on the morphology of hydrothermal products of calcium sulfate hemihydrate in the magnetized water system. With the increment of calcium hydroxide concentration, the morphology of hydrothermal products first changed from fibrous to plate-like, then to columnar. In this process, granular morphology was observed, which may be a mixture of calcium hydroxide and calcium sulfate dihydrate crystals. When the concentration of calcium hydroxide was 5.0×10-7 mol/L, hydrothermal products mainly existed as fibrous. With calcium hydroxide concentration increased to 5.0×10-5 mol/L, Ca2+ inhibited the dissolution of calcium sulfate dihydrate through the common ion effect, resulting in a diminishing of SO42- in the solution. Meanwhile, OH- and SO42- competitively adsorbed on the (002) crystal plane of calcium sulfate hemihydrate crystal in the form of chemical adsorption, which was not conducive to the precipitation of growth components on the crystal plane and led to the morphology transition from fibrous to plate-like. With the concentration of calcium hydroxide further expanded to 5.0×10-3 mol/L, excessive Ca2+ concentration in the solution was beneficial to the growth of hemihydrate calcium sulfate crystals along (200) and (110) crystal planes, while OH- restrained the growth of hemihydrate calcium sulfate crystals on (002) crystal plane. Beneath the combined influence of the above two factors, calcium sulfate hemihydrate transformed into columnar. This work provides references for the preparation of calcium sulfate hemihydrate hydrothermal products with different morphologies in magnetized water systems. Related Articles | Metrics Select Metabolic engineering of Escherichia coli to produce glutaric acid Zhilan ZHANG Cong GAO Liang GUO Xiulai CHEN Wanqing WEI Jing WU Wei SONG Liming LIU The Chinese Journal of Process Engineering    2023, 23 (9): 1340-1350.   DOI: 10.12034/j.issn.1009-606X.222453 Abstract （114）   HTML （4）    PDF （2028KB）（92）       Knowledge map    Save Glutaric acid is an important intermediate, which is widely used in chemical industry, agriculture, medicine and other fields. At present, there are some problems in the biosynthesis pathway of glutaric acid, such as long synthesis path, high consumption of cofactors and low yield. In order to develop an efficient method for the synthesis of glutaric acid, a new way to produce glutaric acid using glucose as substrate was constructed by combining enzyme engineering with metabolic engineering. Firstly, a novel catalytic pathway composed of lysine α-oxidase (LO), monoamine oxidase (MAO), α-ketoacid decarboxylase (KDC) and aldehyde dehydrogenase (ALDH) was designed by database mining. AB initio synthesis of glutaric acid was realized by introducing lysine producing strain E. coli CCTCC M2019435. In order to further improve the synthesis efficiency of this pathway, rational analysis and protein modification were carried out for the rate-limiting enzyme KpALDH of the pathway, and the catalytic efficiency of the enzyme was increased by 66.5 times. On this basis, the yield of glutaric acid was increased by 2.0 times through metabolic engineering to enhance the expression of rate-limiting enzyme KpALDH and block the by-product acetic acid metabolic branch. Finally, the glutaric acid fermentation conditions were optimized, the glutaric acid yield increased to 62.0 g/L at the end of fermentation, and the production intensity and yield reached 1.6 (g/L)/h and 0.3 g/g glucose, respectively. Related Articles | Metrics Select Study on preparation of sustained release microspheres with octreotide based on hydrophobic ion-pairing method Yu ZHU Yi WEI Donglin SUI Jingxuan LIU Fangling GONG Guanghui MA The Chinese Journal of Process Engineering    2023, 23 (12): 1646-1656.   DOI: 10.12034/j.issn.1009-606X.223064 Abstract （114）   HTML （7）    PDF （3357KB）（64）       Knowledge map    Save Octreotide (OCT) is widely used for the treatment of acromegaly, neuroendocrine tumors such as gastrinoma, and ruptured esophagogastric variceal bleeding in clinical. However, due to the short half-life of octreotide, the patients need frequent dosing in the treatment of diseases requiring long-term medication such as acromegaly, which leads to poor compliance. Therefore, it is urgent to develop a long-acting sustained-release formulation that can improve patient compliance. And since octreotide is a small molecule peptide drug that is extremely soluble in water, it tends to escape to the external aqueous phase during the preparation of microspheres, resulting in low drug loading and encapsulation efficiency. In this study, HIP-OCT complexes were prepared by hydrophobic ion-pairing (HIP) method. The effects of charge ratio, pH value, and temperature on the binding efficiency of the complexes were investigated, and the water solubility and dissociation of the complexes were observed. The sodium dodecyl sulfate-octreotide (SDS-OCT) with 93.77% binding efficiency, 9.31% water solubility, and 92.10% dissociation was screened as the optimal complex from the four HIP-OCT complexes. Due to the formation of HIP complexes, the hydrophilicity of OCT was changed and the difficulty of OCT encapsulation in double emulsion method was overcome. The SDS-OCT complex microspheres were prepared by the O1/O2/W double emulsion method combined with the premix membrane emulsification technique. Finally, the uniform SDS-OCT microspheres with particle size of 28.02 μm, Span value of 0.776, drug loading efficiency of 6.51%, and encapsulation efficiency of 72.00% were prepared under the negative pressure solidification, drug concentration of 80 mg/mL and poly(D,L-lactic-co-glycolic acid) (PLGA) concentration of 200 mg/mL. The in vitro accelerated release of the prepared SDS-OCT complex microspheres was basically in line with the trend of zero-level release, and the cumulative release was close to 100%. In vivo pharmacodynamic experiments showed that the microspheres had stable and long-term sustained release within one month. Related Articles | Metrics Select Enzyme-enhanced mixed anaerobic digestion of excess sludge and kitchen waste leachate Tongzhan XUE Xin SUN Weihua LI Xiaoji LIU Kun WANG Xiangyu YAN Houyun YANG The Chinese Journal of Process Engineering    2023, 23 (8): 1208-1219.   DOI: 10.12034/j.issn.1009-606X.222311 Abstract （113）   HTML （2）    PDF （21125KB）（51）       Knowledge map    Save In order to study the effect of hydrolase on the gas production performance of mixed anaerobic digestion of residual sludge and kitchen waste leachate, the residual sludge and kitchen waste leachate from urban sewage treatment plants were used as substrates, and the mixing ratio was 1:1 and 2:1, and protease and cellulase were added in the ratio of 1:1, 1:2, and 2:1 (total enzyme addition amount: 60 mg/g TS) to the mixed solution, and mixed anaerobic digestion at a temperature of (38±0.5)℃. The results showed that the gas production performance and disposal effect was the best when protease and cellulase were added in 1:1 in the 2:1 mixed anaerobic digestion system of residual sludge and kitchen waste leachate. Its daily methane production peak is 60.15 mL/g VS, which is 1.84 times higher than that of sludge digestion alone, and 70.49% higher than that of the same substrate without enzymes; the total methane production was 296.17 mL/g VS, which was 75.99% higher than that of sludge digestion alone, and 62.87% higher than that of the same substrate without enzymes; the removal rates of total solid (TS) and volatile solid (VS) were 41.43% and 67.32%, respectively, which were 14.74 and 27.89 percentage point higher than that of sludge digestion alone, and 8.34 and 21.99 percentage point higher than that of the mixed solution without enzymes in the same group, and there was no ammonia inhibition and VFAs accumulation during the digestion process. Using three-dimensional fluorescence spectroscopy combined with parallel factor analysis, it was found that the fluorescent substances present in the mixed anaerobic digestion process were mainly protein-like, fulvic-like, and humic-like. There were significant differences in protein fluorescence intensity in different time periods of digestion. This change was more pronounced in the enzyme-added experimental group. The results of this study can provide a reference for the reduction and recycling of excess sludge and kitchen waste. Related Articles | Metrics Select Liquid-liquid heterogeneous mixing characteristics of self-priming jet impeller Jing ZHANG Jiaxin YUAN Hongye LI Chengsong ZHANG Bin GONG The Chinese Journal of Process Engineering    2023, 23 (10): 1411-1420.   DOI: 10.12034/j.issn.1009-606X.223040 Abstract （112）   HTML （2）    PDF （29780KB）（79）       Knowledge map    Save As a new type of stirred device, the self-priming jet stirred tank has potential engineering application value in heterogeneous mixing enhanced process. The engineering design and industrial application of self-priming jet stirred tank were restricted by the insufficient research on the mixing characteristics. In this study, the liquid-liquid heterogeneous mixing process in self-priming jet stirred tank was investigated using numerical simulation and experiment. Water and oil were set as continuous phase and dispersed phase, respectively. Realizable k-ε turbulence model and Eulerian-Eulerian multiphase flow model were used to numerically simulate the liquid-liquid heterogeneous flow field in the self-priming jet stirred tank. The enhanced mass transfer mechanism of the self-priming jet impeller was investigated. The results showed that the dimensionless velocity on the axis of self-priming jet pipe was less affected by the stirring speed and the dispersed phase holdup. However, the single-phase flow without oil phase had lower velocity inside the self-priming jet pipe and higher velocity outside the pipe. The flow field and dispersed phase distribution in the stirred tank were significantly influenced by the inclination angle β of self-priming jet pipe. When β<0°, the self-priming flow was formed at lower end of the pipe and the jet was formed at upper end of the pipe, which was unfavourable to the radial mixing of oil and water in the stirred tank. When β=0°, the fluid velocity in pipe was close to the impeller speed, and there was no self-priming and jet flow. The impeller only produced the stirring function, which was not good to axial mixing. When β>0°, the self-priming flow was formed at upper end of the pipe and the jet was formed at lower end of the pipe. The high oil phase fluid was sucked by the self-priming jet pipe, and was jetted downward into the low oil phase fluid. The oil phase moved upward by buoyancy. For the self-priming jet impeller with β>0°, the turbulent kinetic energy at the bottom of stirred tank was effectively increased. β>0° was beneficial to eliminate the flow inhomogeneity and oil-water heterogeneous mixing process was enhanced. When β=30°, the fluid region, which dimensionless phase fraction was 0.95~1.05, accounted for 81.88% of the stirred tank volume, and the oil phase distribution was more uniform along the axial and radial directions. Related Articles | Metrics Select Study on curing arsenic-containing compounds and solid wastes by iron-based silicate gel Boyu DU Chao LIU Xing ZHU The Chinese Journal of Process Engineering    2023, 23 (12): 1714-1724.   DOI: 10.12034/j.issn.1009-606X.223085 Abstract （112）   HTML （5）    PDF （2442KB）（68）       Knowledge map    Save During the mining and metallurgy of non-ferrous heavy metals, a large number of arsenic-containing compounds are exposed to the environment, posing great environmental risks to the surrounding water and soil. Due to their good arsenate affinity, iron ions and their compounds are the main components of commonly used chemical arsenic fixation agents. Whether in arsenic pollutant solidification or arsenic-contaminated site remediation, silicate and hydration processes are important physical barriers to arsenic. Based on this, we synthesized an iron-based silicate gel and evaluated its performance for the solidification/stabilization of typical arsenic compounds [Na3AsO4, Ca3(AsO4)2, AlAsO4, and FeAsO4·2H2O] and arsenic-containing sludge from non-ferrous metallurgy, and explored the arsenic fixation mechanism. The results showed that the iron-based silicate gel with a Fe/Si molar ratio of 1:4 could effectively immobilize the arsenic-containing compounds (Na3AsO4 and FeAsO4·2H2O). However, in the process of curing Ca3(AsO4)2 and AlAsO4, due to the competitive reaction between arsenate and silicate, the toxic leaching of arsenic was higher than that in the process of uncaring. The introduction of CaO could inhibit the competitive reaction, improve the arsenic fixation rate of Ca3(AsO4)2 and AlAsO4, and reach more than 98% of the arsenic fixation efficiency. The synergistic effect of Fe and Ca co-precipitation and physical immobilization is responsible for the immobilization/stabilization of arsenic-containing compounds. The core-shell structure with arsenic-containing compounds as the core and iron-based silicate gel/C-S-H gel as the shell separated arsenic species and reduced toxic leaching when in contact with the surrounding environment. The long-term stability showed that the iron-based silicate gel-cured arsenic-containing waste remained highly stable at pH=8 for 30 days. The CaO-assisted iron-based silicate gel proposed in this work showed great potential for the immobilization of arsenic-containing wastes and arsenic-contaminated land and provided a new way to solidify arsenic-containing pollutants. Related Articles | Metrics Select Preparation of calcium-based composite absorbent and simultaneous removal performance of SOx and NOx from flue gas Yang LI Yang LIU Changming LI Liangliang FU Jian YU The Chinese Journal of Process Engineering    2023, 23 (10): 1446-1457.   DOI: 10.12034/j.issn.1009-606X.222344 Abstract （111）   HTML （3）    PDF （1918KB）（94）       Knowledge map    Save In order to solve the technical problems of simultaneous desulfurization and denitrification of flue gas at ultra-low temperatures (<120℃) by dry process, this work prepared several calcium-based composite absorbents by coupling different strong oxidants with lime of high specific surface area, which can realize the efficient simultaneous removal of sulfur oxides (SOx) and nitrogen oxides (NOx) from flue gas at ultra-low temperature (<120℃). The results of desulfurization and denitrification performance evaluation of calcium-based composite absorbers with different oxidant types and loadings showed that the addition of strong oxidants not only improved the desulfurization performance of Ca(OH)2 but also achieved simultaneous denitrification with Ca(OH)2. The type and amount of oxidant had a significant influence on the simultaneous desulfurization and denitrification of flue gas, and the appropriate moisture and oxygen contents of flue gas were beneficial to improve the desulfurization and denitrification efficiency. According to the characterization results of crystal structure, thermal decomposition, microstructure, and specific surface area of calcium-based composite absorbers before and after the flue gas purification reaction, it can be found that SO2 and NO are first oxidized by strong oxidants, and then react with hydrated lime to generate corresponding sulfates and nitrates, improving the desulfurization and denitrification efficiency. This study is expected to provide a new purification material and process for the upgrading of the intrinsic engineering process or purification of small industrial boilers to achieve ultra-low emission requirements. Related Articles | Metrics Select Experiment research of influence of low concentration surfactant on particle deposition morphology of evaporated sessile drop Chuyue WU Yongqing HE Xi CHEN The Chinese Journal of Process Engineering    2023, 23 (8): 1180-1189.   DOI: 10.12034/j.issn.1009-606X.222355 Abstract （111）   HTML （4）    PDF （40639KB）（65）       Knowledge map    Save Regulation of the deposition morphology after sessile drop evaporation has numerous applications and potential benefits. The drop evaporation of particle suspension with polystyrene particles and sodium dodecyl sulfate (SDS) was experimentally observed and analyzed. The effect of SDS with a concentration of 0wt%~1wt% on the evaporation process of polystyrene particle suspension and the deposition morphology after evaporation was studied. The results demonstrated that the droplet contact angle decreased nonlinearly with the increase of SDS concentration. When SDS was added, spontaneous spreading driven by surface-tension gradient occurred. It was found that the maximum spread coefficient was positively correlated with SDS concentration. The spreading process took only 1/5~1/3 of the total evaporation process time. The gray level co-occurrence matrix (GLCM) was used to analyze the effect of adding SDS on the deposition morphology inside the coffee ring. The SDS could not only regulate the ring width, but also reduce the aggregation of particles in the middle of a deposition, and the deposition was more uniform (the most obvious when the concentration of SDS was 0wt% compared with 0.1wt%). Marangoni flow in the droplet would become more ferocious as SDS concentration rose, and the ring grew broader. There was an upper limit for SDS to regulate the ring width of the annular deposition, as the annular deposition was not readily apparent when the concentration of SDS was higher than 0.75wt%. Most of the particles were uniformly distributed throughout the entire deposition area, forming a disc-like deposition. The maximum percentage of annular deposition area for particles were 58.6% for diameter of 5.7 μm and 44.6% for diameter of 10 μm. It demonstrated that SDS affected the deposition pattern of particles of various sizes in distinct ways. Related Articles | Metrics Select Effect of flow sharing cavity on boiling flow and heat transfer in microchannels He JIANG Junfei YUAN Lin WANG Guyu XING Libei AN The Chinese Journal of Process Engineering    2023, 23 (6): 847-857.   DOI: 10.12034/j.issn.1009-606X.222363 Abstract （111）   HTML （4）    PDF （14425KB）（87）       Knowledge map    Save Aiming at the instability of boiling flow in parallel microchannels heat sink, the boiling flow and heat transfer characteristics of microchannel heat sink with flow sharing cavity with inner arc transition (MC-C) and microchannel heat sink with traditional square flow sharing cavity (MC-S) were studied. Using R134a as refrigerant, the two-phase flow pattern, wall temperature and heat transfer coefficient of microchannel were analyzed under the conditions of mass flow rate of 416~728 kg/(m2?s) and heat flux of 36.7~242.6 kW/m2. The working medium flowed into the inlet flow sharing cavity through the inlet pipe, then flowed through the microchannels, entered the outlet flow sharing cavity, and flowed out of the heat sink through the outlet pipe. The results showed that bubble flow, bubble-slug flow, slug flow, and annular flow changed in the channels when the heat flux increased from low to high. Compared with MC-S microchannels heat sink, the inlet flow sharing cavity of MC-C microchannels heat sink reduced the flow resistance of working fluid, and the outlet flow sharing cavity promoted the steam to be discharged from the microchannels heat sink, and the flow pattern in each microchannel of MC-C microchannels heat sink was more uniform. The wall temperature of MC-C microchannels heat sink increased first, then decreased and then increased, while that of MC-S microchannels heat sink decreased first and then increased. Under the same working conditions, MC-C microchannels heat sink can achieve lower wall temperature. The heat transfer coefficient in two kinds of microchannels heat sink increased with the increase of mass flow rate and heat flux. Under the same working condition, MC-C can achieve higher heat transfer coefficient. When the heat flux was 242.6 kW/m2, the wall temperature of MC-C microchannels was 2.8℃ lower than that of MC-S microchannels, and when the mass flux was 572 kg/(m2?s), the maximum temperature difference of MC-C microchannels was 2.2℃ lower than that of MC-S microchannels. When the heat flux was 242.6 kW/m2, the average heat transfer coefficient of MC-C microchannels was 20.2% higher than that of MC-S microchannels. Related Articles | Metrics Select Screening of ionic liquids as entrainer for separation of water+acetic acid system using COSMO-RS model Qing LI Meng SHI Yimin GUO Ruining HE Yun ZOU Zhangfa TONG The Chinese Journal of Process Engineering    2023, 23 (7): 1063-1072.   DOI: 10.12034/j.issn.1009-606X.222245 Abstract （111）   HTML （7）    PDF （2380KB）（66）       Knowledge map    Save The high-effect wastewater purification has become a serious problem for acetate ester production. The traditional technology for the separation of acetic acid and water including extractive distillation, azeotropic distillation and other methods, which is low efficiency in the selection of entrainer. Conductor-like Screening Model -Real Solvents (COSMO-RS) model can predict the thermodynamic properties of the fluid through quantitative calculation, which is helpful to select the high-effect entrainer for the acetic acid+water system, then simplifying operation and improving efficiency in the research. The latest research shows that organic solvents containing nitrogen and phosphorus have a good extraction effect on the water+acetic acid system. In this study, COSMO-RS model was applied to screen the high-effect entrainer for the separation of water+acetic acid system in extractive distillation, and the high-effect entrainer were specified in the ionic liquids composed of 5 phosphorus anions and 12 imidazole cations. The geometric structures of ions which were not included in COSMO software's original database were optimized by TURBOMOLE quantitative calculation module, and the solvent capacities of water in different ionic liquids, the selectivity of acetic acid to water in different ionic liquids, and the excess enthalpies when ionic liquids were mixed with water or acetic acid were analyzed. The results showed that the extraction effects of [MIM][DBP], [ODMIM][DEP], and [ODMIM][Me2PO4] were better than others. When water or acetic acid was mixed with ionic liquids, hydrogen bonding dominated the intermolecular interaction absolutely. Imidazole cations had strong ability to provide hydrogen bonding, and was easy to combine with acetic acid, so as to improve the relative volatility of water and acetic acid and achieve the purpose of separation. Comparing the excess enthalpy value, the interaction between [ODMIM]+ cation and acetic acid was the strongest intermolecular force. Finally, [ODMIM][DEP] was selected as the high-effective entrainer for the separation of water+acetic acid system. The results provide basic data for the separation of components in water+acetic acid system. Related Articles | Metrics Select Analysis of entropy generation in natural gas ejector Wenhui ZHANG Qi LI The Chinese Journal of Process Engineering    2023, 23 (6): 870-879.   DOI: 10.12034/j.issn.1009-606X.222294 Abstract （109）   HTML （1）    PDF （1944KB）（62）       Knowledge map    Save The size of natural gas ejector under a certain working condition was designed by using the method proposed by the UUSR Institute of Thermal Engineering. The simulations covering 70 groups of ejector models with different structures under different working conditions were conducted adopting RNG k-ε eddy viscosity model and the results were verified by experimental data, and the comparison between the exergy calculated by experiment data and the entropy generation by simulation indicated that the entropy generation analysis method was reliable. The value of entropy generation involving with viscosity, turbulent dissipation, heat transfer with finite temperature difference, and the laminar boundary layer near the wall in ejector was calculated respectively. It was found that the entropy generation due to turbulent dissipation accounts for about 97%, indicating that the friction causing by the turbulent fluctuation was the major part of energy loss. Turbulent entropy generation in ejector was closely related to its diamond shock, oblique shock and shear diffusion between primary and entrained fluid. The axial distribution and peak value of turbulent entropy generation were positively correlated with the position and intensity of the diamond shock in mixing chamber and oblique shock in diffusion chamber, while the radial distribution of turbulent entropy generation gradually transited from the shear boundary layer locating in the middle of jet core and the secondary fluid to the entire cross section. In addition, the performance of the ejector became worse with increasing turbulent entropy generation due to the oblique shock in the expansion chamber. For example, the entrainment ratio would decrease with increasing turbulent entropy generation due to the oblique shock in the expansion chamber caused by excessive expansion ratio. And the energy would be wasted due to the oblique shock in the expansion chamber in a lower compression ratio, although the entrainment ratio remained stable in this condition. Related Articles | Metrics Select Influence of support structure of superbase catalyst on dimerization of propylene to 4-methyl-1-pentene Jing CHAI Haibo JIN Suohe YANG Guangxiang HE Lei MA Xiaoyan GUO The Chinese Journal of Process Engineering    2023, 23 (6): 918-924.   DOI: 10.12034/j.issn.1009-606X.222300 Abstract （109）   HTML （1）    PDF （2103KB）（76）       Knowledge map    Save The catalyst support is an important part of the load-type catalyst. As an active substance with good dispersibility in the skeleton, it can not only increase the strength of the catalyst but also serve as an active center. In addition, the pore structure and specific surface area of the support also have a great influence on the catalytic performance of the catalyst. Therefore, it is necessary to study the structure of the catalyst support. In the catalytic dimerization of propylene to produce 4-methyl-1-pentene (4MP1), 4MP1 is a thermodynamically unstable product, which is extremely easy to be converted into other thermodynamically more stable byproducts. Moreover, the distribution of propylene dimerization products is complex, and the equilibrium conversion rate of each reaction is close to 100%, with a high degree of spontaneity. Therefore, in order to improve the selectivity of 4MP1, a suitable catalyst system should be selected. Solid base catalyst has been widely used in the dipolymerization of propylene to 4MP1 because of its high selectivity and ability to inhibit isomerization. Alkali metal K was supported by alkali metal carbonate, alkali metal bicarbonate, alkaline earth metal carbonate, and alumina of different crystalline forms to prepare solid superbase catalysts for propylene dimerization to 4MP1. The role of catalyst support in the process of 4MP1 formation and the influence of different support properties were systematically summarized. The specific surface area and pore diameter distribution of the carrier material were characterized by a mercury injection meter and scanning electron microscope (SEM). The results showed that the internal diffusion resistance was caused by the pore structure of different carriers, which affected the product distribution of the propylene dimerization reaction. When the target product of the dimerization reaction was 4MP1, the catalyst prepared by using K2CO3 as the support to support alkali metal K had a good 4MP1 selectivity, up to 87.38%. For the propylene dimerization reaction path and 4MP1 isomerization reaction, the material with low specific surface area, large pore diameter, and narrow pore diameter distribution should be preferred as the carrier for the high selectivity of propylene dimerization 4MP1. Related Articles | Metrics Select Comparative study on pyrolysis kinetics of different heavy oil based on distributed activation energy model Qing'an XIONG Yuming ZHANG Jiazhou LI Wei ZHANG Zhewen CHEN The Chinese Journal of Process Engineering    2023, 23 (10): 1421-1434.   DOI: 10.12034/j.issn.1009-606X.222469 Abstract （109）   HTML （1）    PDF （2207KB）（71）       Knowledge map    Save The pyrolysis behavior of Dagang slurry oil (DG-SO), Qingdao vacuum residue oil (QD-VR) and Canadian oil sand bitumen (CA-OB) were investigated by thermogravimetric mass spectrometry. The pyrolysis kinetic parameters were obtained by Friedman method, FWO method, and distributed activation energy model (DAEM), respectively. The results showed that DG-SO with relatively high content of saturates and aromatics had the highest pyrolysis reactivity, while QD-VR with relatively high content of resins and asphaltenes had the lowest pyrolysis reactivity. The releasing curves of H2, CH4, CO, and CO2 correspond to the main reaction temperature ranges of heavy oil pyrolysis. The distinctions of the shape, intensity and temperature range of the pyrolysis gases releasing curves between different types of heavy oils were mainly attributed to the corresponding composition and pyrolysis reactivity of each type of heavy oil. It was clearly found that Friedman method could gain more accuracy for description of pyrolysis process of heavy oil compared with FWO method in terms of equal conversion methods. The average activation energies (Ea) of DG-SO, QD-VR, and CA-OB were 80.15, 177.00, and 174.56 kJ/mol within the conversion range of 0.1~0.9, respectively. The one-component Gaussian DAEM could describe the whole process of SARA (saturates, aromatics, resins, asphaltenes), and their Ea were 107.78, 210.88, 268.75, and 285.44 kJ/mol, respectively. The four-component Gaussian DAEM could be used to precisely describe the whole pyrolysis process of heavy oil, and the calculated weighted average activation energies were 148.92, 205.92, and 190.37 kJ/mol, respectively. By comparing the Ea of QD-VR and its SARA components, it was found that the interaction between the SARA during the pyrolysis of heavy oil leaded to the Ea of QD-VR close to the Ea of aromatics in heavy oil. At the same time, it was found that the presence of resins and asphaltenes increased the average activation energy of saturates and aromatics, while saturates and aromatics reduced the average activation energy of resins and asphaltenes. Related Articles | Metrics Select Numerical simulation of non-oxidative methane dehydroaromatization reactor based on CPFD method Jinfeng SI Ming GONG Xiaojiao JI Xing LIU Xiaoxun MA The Chinese Journal of Process Engineering    2024, 24 (1): 17-26.   DOI: 10.12034/j.issn.1009-606X.223144 Abstract （108）   HTML （6）    PDF （1924KB）（106）       Knowledge map    Save Non-oxidative methane dehydroaromatization (MDA) is a promising technology for converting methane into high value-added products such as benzene, naphthalene, and hydrogen. The fluidized bed has good mass and heat transfer characteristics and is easy to realize the continuous regeneration of the catalyst, so it is an ideal MDA reactor. The basic research on fluidization in MDA fluidized bed reactors is one of the important links to realize the industrialization of MDA technology. In this work, the coupling model of reactions and hydrodynamics was established, and the fluidized bed reactor of the methane dehydroaromatization catalytic reaction/catalyst regeneration system, which has been constructed by our laboratory, was numerically simulated based on the computational particle fluid dynamics (CPFD) method. Then, the simulated values were compared with the corresponding experimental results, which validated the feasibility of CPFD simulation. Through simulation, the overall gas-solid flow state, the concentration distribution of each component in the gas phase and the catalyst carbon deposition content distribution were predicted. Finally, the effects of different operating conditions such as methane feed flow and catalyst retention in the reactor on the gas-solid two-phase flow and methane dehydroaromatization reaction performance were investigated. The results showed that the increase of methane feed flow rate reduced the methane conversion and improve the selectivity of aromatic products. Increasing the catalyst retention in the reactor can improve the methane conversion, meanwhile, it also made the axial and radial non-uniformity of the gas-solid two-phase distribution in the gas-solid reactor more significant, resulting in increased gas backmixing and lower the aromatic selectivity. This work would deepen the understanding of the gas-solid flow patterns inside the MDA fluidized bed reactor and provide some valuable data support for the industrial reactor scale-up of this technology. Related Articles | Metrics Select Evaluation and analysis of ionic liquid-containing wastewater by a novel nanofiltration-flash evaporation coupled recovery process Dian NIU Jianguo QIAN Jian CHEN Guoxiong ZHAN The Chinese Journal of Process Engineering    2023, 23 (8): 1220-1230.   DOI: 10.12034/j.issn.1009-606X.223168 Abstract （108）   HTML （9）    PDF （2225KB）（86）       Knowledge map    Save The highly efficient and low-cost recovery of ionic liquid from the solution remains an issue to realize the reuse of ionic liquid. This work proposes the coupling process combining nanofiltration and vacuum flash evaporation for recovery of ionic liquid in solution. The lower concentration of ionic liquid aqueous solution is concentrated through nanofiltration technology, and then the higher concentration of ionic liquid aqueous solution is treated by the vacuum flash evaporation process to obtain the pure ionic liquid and realize the efficient separation and recovery of ionic liquid. 1-methyl-3-octylimidazolium tetrafluoroborate ([C8Mim][BF4]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2Mim][BF4]) were used as model compounds to explore the recovery effect of the coupling technology by process simulation. Based on the literature reported data on the previous researches, the main physical properties of ionic liquid and ionic liquid-water thermodynamic models were constructed by the regression method. A model of the coupled process of the separation and recovery technology for ionic liquid was established by Aspen Plus simulation software. The influences of different operating conditions on the process separation performance were investigated by the parametrical sensitivities analysis. Then the optimal scenario could be obtained. At the same time, the heat exchanger network of the coupling process was modified which could increase the energy efficiency and reduce the cooling and heating utilities consumption. Moreover, the energy consumption of different processes were analyzed and evaluated to clarify the separation and recovery advantages of the novel coupling process. The results showed that the heating utilities of [C8Mim][BF4] and [C2Mim][BF4] were 11% and 13% of those of the initial scenarios, and the cooling utilities were 15% and 19% of those of the initial scenarios after the heat exchanger network modification. The lowest comprehensive energy consumption of the 2 stage membrane separation-flash evaporation coupling process was 3.9 GJthermal-eq/t IL ([C8Mim][BF4]) and 4.5 GJthermal-eq/t IL ([C2Mim][BF4]), which was only 20% ([C8Mim][BF4]) and 27% ([C2Mim][BF4]) of the direct vacuum flash evaporation process. The results of this study can provide theoretical basis and guidance for the future industrial application of ionic liquid recovery process. Related Articles | Metrics Select CFD simulation study on influence of multi structural parameters of Y-shaped pleated clean filter bag on filtration resistance Wanying SUN Fuping QIAN Simin CHENG Jinli LU Yunlong HAN Qianshuang ZHUANG The Chinese Journal of Process Engineering    2023, 23 (7): 1024-1034.   DOI: 10.12034/j.issn.1009-606X.222326 Abstract （107）   HTML （5）    PDF （17036KB）（79）       Knowledge map    Save It has been proved by long-term practice that pleated filter bags can solve the problem of increasing the filtering area without changing the main equipment and the floor area of the bag filter. However, the filtering performance of this folded filter bag is acceptable only when the number of folds is low. When the number of folds is high, the shortening of the fold spacing will have a certain impact on the filtering and ash removal. In order to study the influence of the change of pleat spacing caused by the increase of pleat number on the filtration performance of pleated filter bags, a new Y-shaped pleated filter bag is proposed in this study to explore the influence of multivariate geometric characteristics on the filtration pressure drop. The three-dimensional filter medium model of polyester fiber filter material is constructed by using GeoDict, and the filter medium penetration model is obtained for the macro numerical simulation of Y-shaped pleated filter bag. Based on the response surface method, the influence of multi structural parameters of Y-shaped pleated filter bag on its filtration performance is explored. The research results show that within a certain range of filtration velocity, GeoDict simulation can be used to replace the experimental test. And the filtration pressure drop of Y-shaped pleated filter bag is lower than that of conventional 8 and 16 pleated filter bags. Wherein, compared with the conventional 8-pleated filter bag the filtration area of Y-shaped pleated filter bag increases by 58.04% when the number of Y-pleats (NY) is 8, the opening angle (α) is 30°, and the concave diameter (d ) is 228 mm, and the outlet velocity distribution uniformity increases by 21.23%. The uniformity of outlet velocity distribution is 28.51% higher than that of conventional 16-pleated filter bag. The optimal structural parameter of Y-shaped pleated filter bag is NY=12, α=20.17°, d=240.18 mm, and the filtration pressure drop reaches the minimum value of 136.67 Pa. Related Articles | Metrics Select Characterization of the bio?oil from hydrothermal liquefaction of algae and industrial sludge Jianwen LU Shipei XU Qingyuan LI Chao WANG Yulong WU The Chinese Journal of Process Engineering    2023, 23 (6): 936-942.   DOI: 10.12034/j.issn.1009-606X.222268 Abstract （106）   HTML （3）    PDF （2524KB）（45）       Knowledge map    Save Hydrothermal liquefaction (HTL) can directly convert high water content biomass into bio-oil, which can realize both the harmless treatment and resource utilization of the feedstock. However, the bio-oil property varies from one material to another. In this work, HTL of Chlorella, paper mill sludge, and pharmaceutical sludge under the same reaction condition was performed, and the yield and properties of the bio-oil obtained from these three feedstocks were compared. From the point of view of the raw materials, Chlorella, paper mill sludge, and pharmaceutical sludge had similar carbohydrate content (35wt%~40wt%), Chlorella had a higher protein content but a much lower ash content than the two sludges. After HTL, the bio-oil yields of Chlorella, paper mill sludge, and pharmaceutical sludge were 31.2%, 15.4%, and 19.3%, respectively, the difference in the bio-oil yield was mainly attributed to the difference of the feedstock composition. In addition, Chlorella bio-oil had the highest carbon content and heating value, followed by paper mill sludge bio-oil, and pharmaceutical sludge bio-oil had the lowest carbon content and heating value. The paper mill sludge bio-oil had the highest energy recovery (53.4%), greater than those from Chlorella bio-oil and pharmaceutical sludge bio-oil. The composition of bio-oil was very complex, including hydrocarbons, chain amides, nitrogen-containing heterocyclic compounds, acids, and other compounds. The peak area percentages of hydrocarbon compounds in Chlorella, paper mill sludge, and pharmaceutical sludge bio-oil were 27.3wt%, 16.7wt%, and 28.9wt%, respectively. The peak area percentage of nitrogen-containing heterocyclic compounds in the paper mill sludge bio-oil was the highest (45.1wt%), and the peak area percentage of acids in the Chlorella bio-oil was the maximum (22.2wt%). Besides, the peak area percentage of chain amides present in the bio-oil followed the trends Chlorella bio-oil>pharmaceutical sludge bio-oil>paper mill sludge bio-oil. Furthermore, the maximum weight loss rate of the bio-oils from two sludges was 220~230℃, lower than that of the Chlorella bio-oil (250℃). The low boiling point (<200℃) compound content in paper mill sludge and pharmaceutical sludge bio-oil (~33wt%) was higher than that in Chlorella bio-oil (23wt%). And the fractions below 400℃ in the three kinds of bio-oils were all above 80%. The results of this study indicate that HTL can realize the resource utilization of algae and sludge. Related Articles | Metrics Select Liquid-liquid dispersion characteristics in stirred tanks with different baffles Hualong QIN Mengke GUO Xiangyang GONG Yiqun TIAN Chunxue PENG Qinghua ZHANG Chao YANG The Chinese Journal of Process Engineering    2023, 23 (8): 1173-1179.   DOI: 10.12034/j.issn.1009-606X.222397 Abstract （106）   HTML （3）    PDF （20993KB）（68）       Knowledge map    Save Baffle is an important part of the stirred tank, and it can effectively improve the flow state of fluid and the effective utilization of power in the stirred tank. In order to reduce power consumption and improve mixing performance of the stirred tank, a zigzag punched baffle has been developed in our previous work. However, its performance in a liquid-liquid stirred tank has not been performed. With taking water and kerosene as a research system, the liquid-liquid dispersion characteristics in stirred tanks with standard baffles (SB), standard punched baffles (SPB), and zigzag punched baffles (ZPB) were studied by numerical simulation. The results showed that due to the formation of the impinging steam, the zigzag punched baffle can effectively reduce the dead zone behind the baffle in the stirred tank. With an increase of stirring speed, the stirring power consumption of the three different baffled stirred tanks all gradually increased, meanwhile the kerosene droplet diameter decreased. At the same stirring speed, the power consumption of the SPB stirred tank was almost the same as that of the SB stirred tank, while the gap between ZPB and SB stirred tanks was growing with the increase of stirring speed. The droplet diameter in the stirred tank with zigzag baffle was much smaller than that of the tanks with standard baffle and the standard punched baffle at the same stirring speed. With the increase of stirring speed, the difference between the droplet diameter of ZPB and SPB and that of SB increased first and then decreased. When the stirring speed is 400 r/min, the difference was the largest. At this time, compared with the SB stirred tank, the droplet diameter of kerosene in the SPB and ZPB stirred tanks decreased by 18.16% and 36.87%, respectively. Related Articles | Metrics Select Study on the mechanism of Ni 2+ and Mg 2+ loss and enhanced separation in sulfuric acid leachate of laterite nickel ore during iron removal using neutralization process Hao JIANG Xin TENG Jun LUO Changye MANG Xinran LI Wenhao SUN The Chinese Journal of Process Engineering    2023, 23 (11): 1558-1567.   DOI: 10.12034/j.issn.1009-606X.223055 Abstract （106）   HTML （2）    PDF （8323KB）（94）       Knowledge map    Save Neutralization precipitation process is often used to remove impurities such as iron, aluminum and chromium from the nickel laterite acid leach solution, however, it accompanied with the loss of nickel and magnesium metal ions. The precipitation behaviors of Ni2+ and Mg2+ ions in nickel laterite acid leach solution during the neutralization precipitation iron removal process was deeply discussed in this work. Furthermore, a novel precipitation mechanism of Ni2+ and Mg2+ with SO42- during the neutralization precipitation iron removal process was proposed. The results showed that under the condition of fixed Ni2+ and Mg2+ concentrations in simulated leachate, the loss rate of Ni2+ and Mg2+ during neutralization and precipitation respectively were 9.13%~23.23% and 9.79%~15.68% with the increase of Fe3+ concentration in simulated leachate. Under the condition of fixed Fe3+ concentrations, the loss rate of Ni2+ and Mg2+ decreased with the increase of the concentration of Ni2+ and Mg2+. According to the results of solution chemical calculation and the characterization of iron hydroxide precipitation by infrared spectroscopy and scanning electron microscopy, both SO42- ions and Fe(OH)3 colloids could co-precipitate in the form of monovalent or binary complex during the neutralization process, in which the lone pair electrons of SO42- in the monovalent complexes bond with Ni2+ and Mg2+ and adsorb, resulting Ni2+ and Mg2+ in the leachate were co-adsorbed with SO42- by Fe(OH)3 colloid and the loss was caused. In addition, it was found that the surfactant such as cetyl trimethylammonium bromide (CTAB), polyethylene glycol (PEG), sodium dodecyl benzenesulfonatecan (SDBS) was added during the neutralization precipitation process can effectively compete for adsorption with neutralizing precipitated products or impede the combination of SO〖_4^(2-)〗 with Ni2+ and Mg2+ ions, which could enhance the selective precipitation of Fe3+ ions during neutralization process. When the dosage of three surfactants was 2×10-5 mol/L, the retention rates of Ni2+ in the process of neutralization and precipitation of iron could reach about 95%, and Mg2+ could reach 100%. Related Articles | Metrics Select Preparation of nitrogen-containing heterocyclic amphoteric resin and its separation performance toward succinic acid Junwei ZHANG Zexiao DONG Miaoxin YUAN The Chinese Journal of Process Engineering    2023, 23 (10): 1478-1487.   DOI: 10.12034/j.issn.1009-606X.222373 Abstract （106）   HTML （5）    PDF （12662KB）（52）       Knowledge map    Save In order to study the performance of an amphoteric resin with hydroxyl group and nitrogen-containing heterocycle used for the separation of succinic acid (SA), a weak acid-weak base resin, shortly called 4-VMVH resin, the copolymerization of 4-vinylpyridine with methyl acrylate and vinyl acetate, was prepared, then the physicochemical property, performance and adsorption mechanism of the resin was explored. The results indicated that more meso- and micro-pores and less macro-pore were determined inside the resin, and the adsorption of SA on the resin was an exothermic process and could be described by Freundlich model. The distribution of adsorption site on the resin was inhomogeneous, and the isosteric adsorption enthalpy of the resin decreased with increasing the fractional loading of SA. The total acid-base exchange capacity and the hydroxyl group content of the 4-VMVH01 resin were 4.607 mmol/g and 114.21 mg KOH/g and higher than that of the 2-VMVH resin. Moreover, the resolution of SA and acetic acid (AcOH) was 0.92 while the recovery rate of SA reached to 84.67% at a ratio of the column height to its diameter of 15/1 with only hot water as eluent, and the reusability of the 4-VMVH resin basically remained constant. The interaction energy between the heterocyclic N atom and the carboxyl H atom of SA was higher than that between the heterocyclic N atom and the carboxyl H atom of AcOH. The interaction energies between hydroxyl O atom and the carboxyl H atoms of SA and AcOH were respectively -26.531 kJ/mol and -25.094 kJ/mol, which belonged to the hydrogen-bonding adsorption, and therefore the retention force of SA on the 4-VMVH resin was stronger than that of AcOH. Related Articles | Metrics Select Numerical simulation of blending effectiveness of forcing mixer based on EDEM Xu GAO Jie LEI Zhanxia DI Shanping LIU Yunfeng SONG Hongming LONG The Chinese Journal of Process Engineering    2023, 23 (11): 1530-1540.   DOI: 10.12034/j.issn.1009-606X.222459 Abstract （106）   HTML （4）    PDF （36544KB）（118）       Knowledge map    Save The mixing effect of raw materials is an important factor affecting the quality and production efficiency of pellets. The forcing mixer is the core mixing equipment, and the appropriate operating parameters can make the mixed materials achieve the best mixing effect. In industry, the basic performance indicators of pellets are generally used to replace the mixing effect of materials, such as falling strength and compressive strength, resulting in long detection process, large error, and inability to visually obtain material trajectory and dispersion effect. In this study, SOLIDWORKS software is used to establish a forcing mixer model, and EDEM discrete element software is used to simulate the movement behavior of materials in the reactor. The effects of the rotating motion of the rotor, the bottom and the wall of the mixer and the filling rate of the materials on the mixing effect are studied. The results show that increasing the rotor speed can significantly improve the mixing effect, but when the rotation speed reaches ±48 r/min, the improvement of the mixing effect is not obvious. The rotation of the bottom can break through the speed threshold of the double rotor rotation, and the bottom can greatly improve the mixing effect at a lower rotation speed of +30 r/min. On the contrary, the rotation of the wall produces a stacking effect, which inhibits the dispersion of the particles, thereby reducing the mixing effect. The high filling rate is not conducive to the dispersion of materials above the rotor blade position, and the mixing effect is the best when the filling rate is 60%. Considering the enterprise pellet production and mixing equipment running performance requirements, the reasonable operating parameters are rotor rotation speed of ±30 r/min, the bottom rotation speed of +30 r/min, the wall rotation speed of 0 r/min, and filling rate of 60%. Related Articles | Metrics page Page 1 of 3 Total 109 records First page Prev page Next page Last page