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Surface modification and catalytic performance study of Cu-based carbon dioxide to methanol hydrogenation catalyst Qiang YANG Gang WANG Chunshan LI The Chinese Journal of Process Engineering    2024, 24 (10): 1166-1176.   DOI: 10.12034/j.issn.1009-606X.224059 Abstract （449）   HTML （17）    PDF （3618KB）（254）       Knowledge map    Save Development of effective copper-based catalyst for CO2 hydrogenation to methanol is of great significance, considering the utilization of this greenhouse gas. In this work, a series of surface promoter-modified (Mn, In, Mo, Mg, Zr) catalyst were synthesized by coprecipitation-post impregnation method and evaluated for CO2 hydrogenation to methanol in fixed-bed reactor. The role of metal modifier on the physicochemical properties of Cu/ZnO/Al2O3 (CZA) were investigated through CO2-TPD, XRD, XPS and H2-TPR. In addition, the catalytic mechanism for CO2-to-methanol hydrogenation was revealed by employing in situ IR. The results showed that the Mn-modified CZA with good reduction behavior, excellent CO2 adsorption capacity and suitable Cu+/Cu0 ratio exhibited the best performance. The metal element loaded on catalyst strengthened the interactions between the copper and support, suppressing the growth of Cu. The appropriate Cu+/Cu0 ratio facilitates the stabilization and conversion of methoxy, resulting in increased methanol production. Compared to the untreated CZA catalyst, the Mn-modified catalyst has more medium strong base sites on the surface, which helps to adsorb more CO2 for further hydrogenation to form formate, methoxyl and other intermediates. The incorporation of metal component in CZA facilitated the catalyst reduction ability. The catalytic mechanism follows the formate pathway and the methoxyl species is the crucial intermediate. The Cu nanoparticles on the catalyst surface showed an increased capacity for H2 dissociation when using Mn-modified CZA catalysts. This is due to stronger metal-carrier interactions. The presence of interstitial H in the carriers contributed to the generation of formate species. The dissociated H atoms from the surface Cu nanoparticles replenished the consumed interstitial H. The modified catalyst's interstitial H presence and enhanced H2 dissociation ability accelerated the formation and conversion of intermediate species, promoting methanol generation. Related Articles | Metrics

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Study on preparation and properties of electrospinning nanofiber membrane for air filtration Simin CHENG Fuping QIAN Chen ZHU Lumin CHEN Wei DONG Huaiyu ZHONG The Chinese Journal of Process Engineering    2024, 24 (5): 599-608.   DOI: 10.12034/j.issn.1009-606X.223252 Abstract （386）   HTML （5）    PDF （4750KB）（125）       Knowledge map    Save It has been proved by long-term practice that because the source of atmospheric aerosol particles is very wide, small size, the composition is very complex, the harm to the environment and human health is very serious. Although the government has taken a series of effective measures to control the pollution sources, it still takes a long time to completely solve the PM2.5 pollution problem. If the public wants to reduce the harm caused by particulate matter, specific measures must be taken to conduct individual protection and indoor air purification. At present, the simplest and most effective method for individual protection and indoor air purification is to filter the particles in the air through fiber filtration materials, thus reducing their content in the air. However, traditional fiber filtration materials have the disadvantages of low filtration efficiency, high filtration pressure drop and high energy consumption in the process of use. Meanwhile, filtration fibers with high filtration efficiency are often accompanied by higher filtration resistance. In order to develop high efficiency and low resistance fiber membrane for air filtration, polyacrylonitrile (PAN) electrospinning nanofibers were prepared by electrospinning. In the preparation process, the mass fraction of PAN and the duration of electrospinning were changed, and the electrospinning nanofiber films with different morphologies and filtration properties were obtained. The morphologies and filtration properties of electrostatic spinning nanofibers were tested and analyzed by field emission scanning electron microscopy and filtration test platform, and the preparation parameters of the best performance PAN electrostatic spinning nanofiber membranes were obtained with PAN mass fraction of 9wt%, electrospinning time of 5.0 h. Under the optimum condition, the film thickness of electrospinning nanofibers was 0.0240 mm, the average fiber diameter was 396 nm, the PM2.5 filtration efficiency was 99.99%, the filtration pressure drop was 67 Pa, and the highest quality factor was 0.137 Pa-1. Related Articles | Metrics

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Research progress of microreactor technology in gas-liquid two-phase flow systems Xinran YE Zan WU Haiou WANG Jianren FAN The Chinese Journal of Process Engineering    2024, 24 (9): 1001-1015.   DOI: 10.12034/j.issn.1009-606X.224035 Abstract （382）   HTML （23）    PDF （3984KB）（221）       Knowledge map    Save Microreactors possess advantages such as high heat and mass transfer efficiency, strict control of reaction parameters, ease of scale-up, and good safety performance, and hold promises for enabling and accelerating the discovery of flow chemistry towards highly efficient and more sustainable chemical synthesis. Gas-liquid multiphase catalytic reaction is commonly encountered in chemical production process, where the reaction stream enters the microfluidic channel in a continuous flow and undergoes rapid reaction. The combination of microreactor technology and gas-liquid multiphase catalytic reaction facilitates the development of efficient and sustainable chemical production techniques. Gas-liquid multiphase catalytic microreactors can be classified as wall-coated or filled-bed microreactors based on catalyst fixation approaches. By optimizing the geometric structure design of the microreactor, it is possible to further reduce the reaction time, minimize the material retention and suppress the occurrence of undesirable reactions, thus improving the microreactor performance. However, the optimization of microreactor structure requires a comprehensive understanding of various physics including the flow characteristics of gas-liquid fluids, the mass transfer mechanism and reaction kinetics within the microreactor. Both the flow pattern and mass transfer of multiphase fluids in microreactors will affect the reactor performance. Investigating the gas-liquid system in microreactors promotes improved design of practical devices. This review mainly summarizes typical gas-liquid microreactor examples, and hope to provide inspiration and guidance for the design, fabrication, and application of microreactors. The review is organized as follows, first, the features of microreactor technology are introduced and the optimization strategies for microreactor structures are presented, which is followed by a detailed discussion on the flow patterns, mass transfer characteristics and bubble breakup dynamics in gas-liquid multiphase systems within microreactors. Then, examples of multiphase catalytic microreactors in applications (mainly focusing on wall-coated microreactors and filled-bed microreactors) and their limitations are introduced. Finally, the research trends and application prospects in gas-liquid multiphase microreactors are envisaged. Related Articles | Metrics

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Investigation of phase structure stability and thermal expansion coefficient of ytterbia stabilized hafnia Fei ZHOU Hao LAN Xiaoming SUN Huifeng ZHANG Yonghui SUN Lingzhong DU Weigang ZHANG The Chinese Journal of Process Engineering    2024, 24 (5): 580-588.   DOI: 10.12034/j.issn.1009-606X.223074 Abstract （345）   HTML （6）    PDF （4295KB）（66）       Knowledge map    Save Improvement of the thrust weight ratio of gas turbine engine rely on increased engine operating temperature. At present, it is a priority to find new thermal barrier coating ceramic materials with a higher temperature tolerance than the traditional YSZ (Yttria partially stabilized zirconia) material and match thermal expansion coefficient of Ni-based superalloy matrix. A series of ytterbia stabilized hafnia (YbSH) were prepared with hydrothermal nano-powders by solid-state sintering. Effects of the ytterbia on the microstructure, phase stability, and thermal expansion coefficient of the doped hafnia ceramics were investigated. The microstructure and phase stability mechanism of Yb2O3-doped HfO2 powders and ceramics were analyzed by XRD, Raman, and TEM. DSC-TG and TMA were used to test the high temperature phase structure stability and thermal expansion coefficient of cubic phase structure of YbSH ceramics. The results showed that the grain size of the hydrothermal nano-powder was less than 10 nm, with a uniform distribution and a great crystal state. Most of the powers were cuboid and the density of the sintered ceramics can reach more than 95%. Crystallography analysis revealed that the Yb(III) ion distorted the lattice by replacing Hf(IV) ion position which made the space group of HfO2 from monoclinic phase distortion of P21/c to the cubic phase Fmˉ3m. The hafnia gradually lost its monoclinic phase structure with increasing doping amount of ytterbia, once the doping concentration of ytterbia raised up to 12 mol/mol. By expanding cationic network and generating oxygen vacancy, oxygen overcrowding was effectively alleviated. The cubic phase structure showed good stability from room temperature to 1500℃ by high temperature heat treatment and monitoring enthalpy change of YbSH nanopowders and ceramics during heating process. Average thermal expansion coefficients of YbSH ceramics increased with cubic phase content increasing from 6.016×10-6℃-1 to 10.14×10-6℃-1 (from room temperature to 1500℃). The thermal expansion coefficient of YbSH ceramics doped with 20 mol/mol ytterbia can reach 10.5×10-6℃-1 (from 1000℃ to 1200℃), which was 67.22% higher than that of pure hafnia. Related Articles | Metrics

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Research progress of lithium extraction technology from lepidolite Hong YANG Wei ZHONG Faping ZHONG Jiahui ZHAO Dong LI Lei ZHANG Xueyi GUO The Chinese Journal of Process Engineering    2024, 24 (11): 1251-1262.   DOI: 10.12034/j.issn.1009-606X.224019 Abstract （338）   HTML （14）    PDF （1677KB）（129）       Knowledge map    Save Lithium and its compounds are indispensable materials in modern industry and have important applications in the fields of batteries, ceramics and lubricants. China is rich in lithium resources, most of which occur in salt lake brine. However, due to the limitation of resource endowment and geographical location and climate, its production capacity cannot meet the needs of the rapid development of new energy industry in China, and lithium extraction from ores has become an important source of lithium products. Yichun, Jiangxi province has the largest associated lepidolite resources in China, and the development and utilization of lepidolite resources is of great significance to ensure the sustainable development of lithium resources in China. In this review, the principle, advantages and disadvantages of the existing lithium extraction processes from lepidolite are summarized. Based on the understanding of the existing methods, typical lithium extraction processes from lepidolite such as acid method, alkali method and salt method are summarized and evaluated. Among them, the acid method is mature, but there are some problems such as difficulty in impurity removal from leaching solution, low efficiency in lithium extraction and equipment corrosion. Although the alkali process has high efficiency of extracting lithium, its reaction mechanism is not clear, and the waste residue is difficult to use. Although the salt process has high selectivity to lithium and simple process, it also has the problems of high energy consumption and large amount of slag. The development direction of lepidolite extraction technology should focus on the collaborative treatment of multiple technologies to achieve efficient, economical and environmentally friendly extraction of valuable elements. Therefore, some measures to improve the process are put forward, aiming at providing reference for the future research, development, optimization and industrial application of the process. Related Articles | Metrics

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Fault diagnosis based on DA-CycleGAN for multimode chemical processes Wenjing CHEN Changchun DAI Yagu DANG Yiyang DAI Xu JI The Chinese Journal of Process Engineering    2024, 24 (5): 618-626.   DOI: 10.12034/j.issn.1009-606X.223316 Abstract （318）   HTML （9）    PDF （1362KB）（205）       Knowledge map    Save In modern chemical processes, timely and accurate fault diagnosis is important for enhancing the safety and reliability. Data-driven fault diagnosis methods have been regarded as a promising approach in the last decades of research for increasingly complex chemical processes. Data-driven fault diagnosis methods can greatly reduce the dependence on human experience, and realize end-to-end fault diagnosis by automatically extracting features. However, most existing research assumes training and testing data come from the same distribution, while a chemical process may have multiple working conditions. On the one hand, the fault diagnosis performance of the model will deteriorate when the process is run under new working conditions. On the other hand, due to the low probability of failure, some operating conditions may have few fault data in history. To address these issues, in this work, a novel fault diagnosis method, DA-CycleGAN, is proposed for multimode chemical processes. This study is the first to overcome the degradation of model diagnosis performance when only normal data are available under new working conditions. It notes that the normal data is available under any working condition. A two-dimensional CycleGAN is used to capture the temporal and spatial features of fault data. And fault data is generated by combining fault features and normal data under new operating conditions, thus filling a blank in new working conditions for fault data. Furthermore, the domain adaptation method is used to minimize the distribution differences between historical fault data and generated data and to improve the fault diagnostic performance under new operating conditions. To test the performance of this method, four working conditions of the Tennessee-Easthman (TE) process are used in the experiment. The results on twelve condition-changed fault diagnosis tasks show that this method can improve the average fault diagnosis rate by more than 3% compared to the model trained using only historical fault data. Related Articles | Metrics

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Research progress in preparation of silicon-based anode materials for lithium-ion batteries by radio-frequency induction thermal plasma Zongxian YANG Yuanjiang DONG Chang LIU Huacheng JIN Fei DING Baoqiang LI Liuyang BAI Fangli YUAN The Chinese Journal of Process Engineering    2024, 24 (5): 501-513.   DOI: 10.12034/j.issn.1009-606X.223230 Abstract （311）   HTML （16）    PDF （7425KB）（171）       Knowledge map    Save As one of the next-generation anode materials with the most promising application prospects, silicon anode benefits from a high theoretical specific capacity, a sufficient working potential, abundant and inexpensive sources, environmental friendliness, safety, and dependability. However, Si will experience significant volume variations throughout the lithiation and delithiation processes. This will result in significant internal stress, which will cause issues including material pulverization, repetitive growth of the solid electrolyte interface (SEI), and electrode failure. Through the utilization of nano-silicon-based anode materials, it is possible to effectively mitigate the volume impact, enhance both conductivity and stability. The utilization of radio-frequency (RF) induction thermal plasma offers several notable benefits, including elevated temperatures, rapid cooling, precise control, and uninterrupted operation. Thermal plasma has the ability to provide particles a unique growth environment and process that is helpful in the creation of products with special morphologies, such as zero-dimensional nanospheres and one-dimensional nanowires. Additionally, the extremely high temperatures can totally evaporate raw materials, guarantee uniformity of product, and be advantageous for doping second-phase materials. Consequently, it serves as a significant method for the production of nano-silicon-based anodes with a controllable morphology and structure, as well as high purity and excellent dispersibility. This work provides a review of the scientific advancements pertaining to silicon-based anode materials for lithium-ion batteries that are fabricated using RF thermal plasma. To commence, a concise introduction is provided for the thermal plasma technology. Then, this work focuses on the synthesis of various essential materials using thermal plasma, including silicon nanospheres (Si NSs), silicon nanowires (Si NWs), silicon monoxide nanowires (SiO NWs), silicon monoxide nanonetworks (SiO NNs), high-silicon silicon suboxide nanowires (SiOx NWs), silicon-based ferrosilicon alloy nanospheres (Si/FeSi2 NPs). Furthermore, the work emphasizes the applications of these materials in the anode electrode of lithium-ion batteries. Finally, the development of thermal plasma technology is prospected. Related Articles | Metrics

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Study of flow field characteristics and separation performance of inline cyclone gas-liquid separator Ming ZHANG Huan SUN Qiangqiang WANG Jiaqing CHEN Chao SHANG Xiang LI Chunsheng WANG Lingzhen KONG The Chinese Journal of Process Engineering    2024, 24 (7): 772-782.   DOI: 10.12034/j.issn.1009-606X.223312 Abstract （306）   HTML （9）    PDF （6151KB）（125）       Knowledge map    Save The inline cyclone gas-liquid separator has received much attention because of its high separation efficiency and compact structure, but the ability to adapt to a wide range of inlet gas holdup is the key to its practicality. In this work, the flow field characteristics and separation performance of a inline cyclone gas-liquid separator that can adapt to a wide range of gas holdup changes are investigated by computational fluid dynamics (CFD) and experimental tests in air-water media system. The CFD numerical simulation results show that when the inlet gas holdup changes in the range of 10%~90%, the gas-phase separation efficiency is greater than 80% and the amplitude of change is less than 9.9%, and the liquid-phase separation efficiency is greater than 97% and the amplitude of change is less than 2.2%. The experimental results show that when the inlet gas holdup changes in the range of 9.4%~89.2%, the liquid holdup of the gas-phase outlet gradually decreases and the gas holdup of the liquid phase outlet gradually increases with the increase of the inlet gas holdup. The liquid holdup of the gas-phase outlet is less than 4%, and the gas holdup of the liquid-phase outlet is less than 10% except at liquid flow rate of 12 m3/h. Comparing the gas-phase separation efficiency and liquid-phase separation efficiency under different liquid flow rates, the best separation performance is achieved at a liquid flow rates of 8 m3/h. The CFD numerical simulation results are slightly different from the experimental test results, but the overall trend is consistent, which can be used as an effective tool for the design of structure enlargement. The research results show that the inline cyclone gas-liquid separator adopts the action form of "strong cyclone+weak cyclone+gravity", which has high separation efficiency and good resistance to fluctuations in working conditions. Related Articles | Metrics

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Research progress on the mechanism and influencing factors of microorganisms to increase coalbed methane production Na ZHANG Xuefeng YIN Zichen WANG Hao LIU Minjie HUANG Hao WANG Dongxu LIANG Jianan HU The Chinese Journal of Process Engineering    2024, 24 (6): 636-646.   DOI: 10.12034/j.issn.1009-606X.223310 Abstract （254）   HTML （10）    PDF （1144KB）（139）       Knowledge map    Save Microbially enhanced coalbed methane (MECBM) is an innovative technology for the extraction and utilisation of coalbed methane (CBM), which involves the microbial degradation and conversion of certain organic components of coal into methane gas. MECBM has great potential and environmental characteristics, and offers the prospect of establishing a new type of energy system, which will hopefully lead to the development of a sustainable energy source, and will effectively alleviate the challenges posed by energy shortages and greenhouse gas emissions. However, widespread application of MECBM technology faces the obstacles of historically low natural CBM production and sub-optimal quality. In order to understand the production potential of coal biogenic methane and the factors controlling the process, with a view to advancing the direction of its research towards continuous progress and effectively increasing coalbed methane production. This review summarises the mechanism and influencing factors of microbial CBM production, providing a theoretical basis for microbial CBM production. Firstly, the background and current research status of microbial production of CBM are reviewed. Subsequently, the basic theory and reaction process of coal biogenic methane production are summarised, showing that acidification of methoxy plays a decisive role in the process of coal biogenic methane production. Then, the environmental and biological factors affecting microbial enhancement of coalbed methane production are summarised, including the temperature of the coalbed, inoculum amount, nutrient addition, and pretreatment method. These factors have a significant impact on microbial CBM production, and optimising natural gas production conditions can not only increase CBM production but also significantly improve the methane concentration in CBM. In conclusion, microbial enhanced CBM technology has great potential and is expected to provide new solutions to the problems of energy shortage and greenhouse gas emissions by optimising production conditions and improving the viability and adaptability of microorganisms. Finally, this study outlines the current challenges and areas for further research in biogenic CBM development, providing a theoretical basis for increasing on-site production and enhancing CBM development. Related Articles | Metrics

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Main advances in preparation technology of zirconia hollow microspheres Baoqiang LI Huacheng JIN Fei DING Chun WANG Fangli YUAN The Chinese Journal of Process Engineering    2024, 24 (6): 627-635.   DOI: 10.12034/j.issn.1009-606X.223297 Abstract （250）   HTML （10）    PDF （1939KB）（164）       Knowledge map    Save Zirconia hollow microspheres have attracted more attention because of their excellent performance, which combines the advantages of the properties of zirconia and hollow structural materials, such as low thermal conductivity, ablation resistance, and chemical corrosion resistance. Zirconia hollow microspheres is an important feedstock for preparing thermal barrier coatings. The thermal barrier coating prepared by zirconia hollow microspheres has the characteristic of excellent insulation and corrosion resistance. The performance of the coating is determined by the characteristics of the powder. The preparation of high quality zirconia hollow spherical powder has become a hot topic in the industry. In this work, the research status of the preparation technology of zirconia hollow spherical powder is analyzed, and the main preparation approaches are introduced, including templating, solvothermal, spray drying, and plasma sintering. In addition, the characteristic of these approaches is briefly summarized. Templating method contributes to obtaining hollow zirconia spheres with perfect morphology. However, some problems such as difficulty both in template synthesis and subsequent template removal, which can cause the material waste and damage to hollow particles. For solvothermal method, the reaction conditions are relatively harsh, and it also involves cumbersome process, such as separation, washing and drying process, which makes it difficult to batch preparation of hollow microspheres. The spray drying method is an effective approach for batch preparation of hollow microspheres. However, the hollow microspheres prepared by spray drying possesses have low strength and become easy to be damaged during application. Importantly, it is considered that the hollow microspheres prepared by spray drying combined with plasma sintering process have the advantages of high sphericity, good fluidity, and controllable particle size distribution, which are more conductive to preparation of coatings. Related Articles | Metrics

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Preparation and photocatalytic performance of Bi2MoO6/Bi7O9I3 heterojunction Benping LIN Yongxiang LI Hanbo YU Chunhua LIU The Chinese Journal of Process Engineering    2024, 24 (5): 589-598.   DOI: 10.12034/j.issn.1009-606X.223229 Abstract （237）   HTML （11）    PDF （4804KB）（68）       Knowledge map    Save Bismuth oxide bismuth molybdate (Bi2MoO6) is a typical Bi(III) based semiconductor with visible light driving characteristics, which has advantages such as good ion conductivity, narrow bandgap, and environmental friendliness. However, the practical application of Bi2MoO6 monomer is severely limited due to its poor intrinsic photo-generated carrier separation, high recombination rate, and narrow light response range. Constructing heterojunctions is an effective method to improve their photocatalytic performance, which not only expands the light absorption range but also promotes the separation of photo-generated charge carriers. However, the construction of heterojunctions has the drawback of lattice mismatch at the interface of two substances, which hinders charge transfer between the interfaces. The one-step synthesis of composite catalysts can effectively reduce the lattice mismatch at the interface, promote the spatial separation of photo-generated electrons and holes, and expand the light absorption range of catalytic materials. In this study, Bi2MoO6/Bi7O9I3 heterojunction materials were synthesized by one-step method. The morphology, chemical composition and photoelectric properties of the heterojunction materials were characterized by instrumental analysis. The effect of material adsorption and photocatalytic degradation of ciprofloxacin (CIP) was studied. The results showed that compared with the single component, Bi2MoO6/Bi7O9I3 composite improved the visible light absorption capacity of Bi2MoO6 monomer, reduced its band gap width, and improved the activity of CIP adsorption and photocatalytic degradation. When the molar ratio of Bi2MoO6 to Bi7O9I3 was 7:3, the best removal rate of CIP was obtained. The absorption removal and photocatalytic degradation rates of CIP were 82.6% and 94.7%. Under the same conditions, the adsorption and degradation rates of monomer Bi2MoO6 and Bi7O9I3 were only 57.4% and 66.4%, 35.2% and 43.6%, respectively. Free radical capture experiments showed that the main active species of Bi2MoO6/Bi7O9I3 photocatalytic degradation of ciprofloxacin were h+ and ?O2-. Related Articles | Metrics

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Study on the heat transfer characteristics of nanofluid spray cooling with ethylene glycol aqueous solution as base fluid Nianyong ZHOU Yingjie ZHAO Yang LIU Youxin ZOU Guanghua TANG Qingguo BAO Wenyu LÜ The Chinese Journal of Process Engineering    2024, 24 (5): 514-522.   DOI: 10.12034/j.issn.1009-606X.223205 Abstract （237）   HTML （5）    PDF （3100KB）（46）       Knowledge map    Save In recent years, due to the improvement of power density, compact packaging and high performance requirements, the heat dissipation demand of high heat flux devices has increased significantly. In view of the above problems, this work plans to use the spray cooling technology to conduct heat transfer research on the Al2O3 nanofluid with ethylene glycol water as the base fluid, focusing on the analysis of the influence of the concentration of the base fluid, the concentration of nanoparticles, and the concentration of the added dispersant on the heat transfer performance of the working medium spray cooling at three different operating conditions of 300, 500, and 700 W. The experimental results show that due to the decrease of specific heat capacity and thermal conductivity and the deterioration of spray characteristics, the mass fraction of ethylene glycol increases from 30wt% to 80wt%, and the surface heat transfer coefficient of Al2O3 nanofluid solution decreases continuously, with an average decrease of 41.63%. The surface heat transfer coefficient of Al2O3 nanofluid shows a trend of first decreasing, then increasing, and then slowly decreasing with the increase of nanoparticle mass fraction. When the mass fraction of Al2O3 nanoparticles increases from 0 to 2wt%, the overall average surface heat transfer coefficient of Al2O3 nanofluid solution decreases by 6.94%. The deposition and bubbling effect are the main reasons for weakening the heat transfer. At the same time, the increase in the mass fraction of nanoparticles improves the thermal conductivity of the nanofluid solution, which to some extent enhances heat transfer. In addition, the addition of a low-quality non-ionic surfactant (Tween-20) can improve the foaming effect, making the heat transfer coefficient of spray cooling increase by about 1.52%, but still lower than that of pure base liquid; Adding a higher mass fraction of dispersant can cause aggregation between nanoparticles and further weaken the heat transfer performance of the thermal conductivity solution. Related Articles | Metrics

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Simulation of flow field evolution in fluidized bed based on artificial neural network Xueyan WU Tianle SHI Fei LI Sansan YU Chunxi LU Wei WANG The Chinese Journal of Process Engineering    2024, 24 (8): 904-913.   DOI: 10.12034/j.issn.1009-606X.224006 Abstract （237）   HTML （6）    PDF （9961KB）（174）       Knowledge map    Save Computational fluid dynamics (CFD) is a commonly used method to simulate complex gas-solid flow in fluidized beds. Due to the solution of partial/ordinary differential equations, the computational efficiency of this method is still low even if the coarse-grained method is used. The flow field simulation method based on data-driven artificial neural network (ANN) model can avoid the equation solving process and achieve efficient calculation. At present, researchers have applied the ANN model to the prediction of single-phase flow field, and there are only a few studies on the complete fluidized gas-solid two-phase flow field. This work combines CFD and ANN to develop an ANN based field evolution model that quickly obtains the evolution of the flow field in the fluidized bed. Compared with those complex large models, a compact network model has been developed and can be used to complete the prediction of complex two-phase flow field. The model includes different network structures for predictions of particle concentration, gas pressure, and gas-solid two-phase velocity. The results obtained by simulating the fluidized bed with the multiphase particle-in-cell (MP-PIC) method are used as data sets for training. The verification results show that the ANN model successfully realizes the prediction of particle concentration, gas pressure, and gas-solid two-phase velocity in the fluidized bed. In terms of accuracy, the ANN model can accurately predict the flow field in a time step, and there are still obvious errors in the long-term flow field prediction. In terms of computational efficiency, the calculation speed of the ANN model is about 13 000 times that of the MP-PIC method. The multi-time-step continuous prediction performance of current model gradually deteriorates with time, and further research still needs to be done to improve this issue. Related Articles | Metrics

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Preparation of sodium bicarbonate modified biochar and analysis of its adsorption mechanism for carbamazepine in water Jihuan ZHANG Jinwei ZHANG Wenlong WU Siqiang Lin Yan LI Lei DING The Chinese Journal of Process Engineering    2024, 24 (9): 1106-1119.   DOI: 10.12034/j.issn.1009-606X.223363 Abstract （236）   HTML （15）    PDF （2886KB）（178）       Knowledge map    Save This study used agricultural waste silk gourd complex powder as raw material and sodium bicarbonate as activator to prepare sodium bicarbonate modified biochar (SBC) that can efficiently adsorb carbamazepine (CBZ) in water through impregnation pyrolysis method. The physical and chemical characteristics such as surface morphology, pore size distribution, functional groups, and degree of graphitization are analyzed through characterization methods. The effects of temperature, dosage, pH and other factors on the adsorption of CBZ in water by SBC are studied through batch experiments. The results show that compared to the original biochar (BC), SBC has a higher specific surface area of 531.43 m2/g and a richer pore size structure. The effect of pH on the adsorption of CBZ by SBC is minimal, and SBC is almost unable to adsorb large molecular humic acids. The Sips model can better describe the adsorption equilibrium law of CBZ on SBC, with an adsorption capacity of 125.52 mg/g at 298 K. Thermodynamic analysis shows that the adsorption of CBZ by SBC is a spontaneous endothermic process, with physical adsorption being the main process. By analyzing the energy distribution of SBC sites and density functional theory, the enhanced adsorption mechanism of CBZ on SBC is further explored. The results show that hydrogen bonding, π-π electron acceptor donor, and pore filling are involved in the process of SBC adsorption of CBZ. Methanol can effectively regenerate saturated SBC, and after four adsorption desorption cycles, the adsorption capacity of SBC for CBZ remains at 68.132 mg/g. This article uses agricultural and forestry waste sponge gourd as a carbon source to prepare biochar for removing pollutants from water, providing a feasible approach to simultaneously achieve the resource utilization of agricultural waste and reduce environmental pollution. Related Articles | Metrics

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Research progress on dissolution behavior of drugs based on the drug-excipient interaction Kunwang SONG Yewei DING Chen SHEN Haomin WU Yuanhui JI The Chinese Journal of Process Engineering    2024, 24 (10): 1127-1136.   DOI: 10.12034/j.issn.1009-606X.224021 Abstract （236）   HTML （20）    PDF （840KB）（63）       Knowledge map    Save Pharmaceutical excipients, also known as "inactive ingredients", are other components in pharmaceutical preparations besides active ingredients. Pharmaceutical excipients are an indispensable and important component in pharmaceutical preparations, and they can significantly affect the release performance of pharmaceutical preparations by forming drug excipient interactions, which is crucial for the effectiveness and safety of pharmaceutical preparations. The development of high-end preparations also puts higher requirements on excipients. Therefore, it is necessary to analyze the mechanism by which excipients in high-end formulations affect the quality of drug formulations. Although the addition of excipients can enhance the release and bioavailability of active ingredients in drugs, improve and maintain drug stability, achieve controllable targeted release of drugs, and act as masking and sweeteners to improve drug bioavailability and patient adherence, more and more studies have shown that excipients can produce physiological activity and affect drug pharmacokinetics, causing adverse reactions such as allergies or intolerance. Large amounts of ingested excipients may also inhibit drug release by interacting with drugs. This review briefly describes the impact mechanisms of commonly used excipients on drug release from the perspective of drug excipient interactions, such as polymers and mesoporous silica. At the same time, it summarizes the research progress of excipient controlled drug release mechanisms based on mathematical models, molecular simulations, and machine learning methods based on drug excipient interactions, and proposes the development direction of future pharmaceutical excipient database establishment for high-throughput screening of suitable pharmaceutical excipients. Determine the optimal drug loading and excipient addition, and provide data support and theoretical guidance for selecting appropriate production processes. Related Articles | Metrics

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Bed characterization and flow heat transfer simulation of fixed bed reactor with low tube to particle diameter ratios Weinan MO Youyong SU Dongdong ZHU The Chinese Journal of Process Engineering    2024, 24 (6): 692-704.   DOI: 10.12034/j.issn.1009-606X.223294 Abstract （234）   HTML （7）    PDF （6094KB）（113）       Knowledge map    Save Tubular fixed beds are widely used in high-temperature catalytic cracking processes. Investigating the structural characteristics of fixed beds with low tube to particle diameter ratios and the flow heat transfer laws at high temperatures can provide valuable insights for optimizing the fixed bed high-temperature catalytic cracking process. To address the issues of inaccurate particle description in the discrete element method and difficulty in mesh delineation in the particle resolution method, a new contact point method is proposed. This method does not alter the particle and bed size and shape parameters, adapts to various particle shapes, and significantly reduces the difficulty of model contact processing. Three cylindrical particle beds with different ratios of the inner diameter of the reaction tube to the equivalent diameter of spheres of equal specific surface area of the cylindrical particles (tube-diameter ratio D/dp) and one spherical particle bed are generated to investigate the effects of tube size ratio and particle shape on bed structure and flow heat transfer characteristics. The results show that the overall void ratio of the bed layer decreases with increasing tube to particle diameter ratio, the particle stacking is distributed in circles, and the radial distribution curves of radial void ratio and axial mean velocity are highly consistent. Additionally, the pressure drop is generally consistent with Eisfeld modified equation. Furthermore, the bed flow field distribution is highly correlated with the bed structure, and the size of the flow channel voids directly affects the generation of channel flow phenomena, which further impacts its temperature field distribution and heat transfer performance. The sphere particle bed exhibits a more uniform temperature field distribution, but its heat transfer performance is not as good as that of the cylind particle bed. Related Articles | Metrics

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Preparation of high-purity copper by electrolytic refining in nitric acid system Mengyang LI Liang XU Tao GE Rui HE Xiaoyu HAN Cheng YANG Zhuo ZHAO The Chinese Journal of Process Engineering    2024, 24 (8): 955-963.   DOI: 10.12034/j.issn.1009-606X.223333 Abstract （230）   HTML （4）    PDF （2577KB）（118）       Knowledge map    Save High-purity copper has been widely used in semiconductor materials, optoelectronics and other fields due to its excellent physical and chemical properties such as ductility, thermal conductivity and electric conductivity. With the rapid development of electronic information industry, the copper product with high purity is pressing needed. Numerous methods such as zone melting, electron beam melting and electrolytic refining have been developed for the preparation of high-purity copper. Among these technologies, electrolytic refining has been investigated extensively and used in the industrial production for high-purity copper owing to its operation flexibility, simple-process and environmental-friendliness. In general, the electrolytic refining methods for the preparation of high-purity copper could be divided into nitric acid system and sulfuric acid system electrolytic refining. The electrolytic refining for high-purity copper preparation in sulfuric acid system has been widely used in industry. However, the high-purity copper prepared in sulfuric acid system generally contains the higher content of impurity elements such as S than in nitric acid system. Therefore, in this study, the 5N purity of copper was prepared from the raw materials of 4N copper in nitric acid system by one-step electrorefining. The effects of H2O2 addition, current density, electrolyte pH, Cu2+ concentration during the electrorefining process were systematically studied. Under the optimum conditions of Cu2+ concentration of 80 g/L, pH of 1.0, H2O2 addition of 0.10 mL/100 mL, and current density of 200 A/m2, the electrolytic product deposited on the cathode surface exhibited the smooth morphology, and the current efficiency during the electrorefining process was over 97%. Furthermore, the impurity elements including S, Ni, Se, As, Sb, Pb, Bi in the electrolytic product were detected by ICP-MS. The results showed that the purity of the copper prepared under the optimum conditions reached the 5N grade, which was consistent with the national standard of 5N high-purity copper. Related Articles | Metrics

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Study on stability of SiO/C slurry and semi-dry homogenization process Feng LIU Cheng LU The Chinese Journal of Process Engineering    2024, 24 (9): 1080-1087.   DOI: 10.12034/j.issn.1009-606X.223365 Abstract （225）   HTML （8）    PDF （4869KB）（125）       Knowledge map    Save Si based anode has become a research hotspot for high energy density lithium batteries due to its high specific capacity, and the preliminary production and application of SiO has been realized. The electrical performance, lifetime and consistency of lithium-ion battery are directly related to its electrode performance, and homogenization is a key process in the electrode production. The stability of SiO/C anode slurry was studied and a semi-dry homogenization process was innovatively developed. The stability of SiO/C-1 and SiO-2 with 1.6wt% and 3.1wt% of carbon was compared in aqueous slurry, and the gas production of SiO/C-1 was obvious in the water due to the fact that Si reacted with H2O to form H2 under alkaline condition, while there was no gas production of SiO/C-2, and the condition of the slurry and the electrode was better. SEM, EDS, and TEM showed that SiO/C-2 had a uniform carbon coating layer with a thickness of 20~30 nm, which can block water and improve the stability, and in the application of SiO/C, it was necessary to pay attention to the carbon coating of the material. In order to improve the stability of SiO/C anode electrode slurry to improve the homogenization efficiency, a semi-dry homogenization process was developed, through the testing of slurry solid content, viscosity, fineness, rheology, gas production and the peeling force, resistance of the electrode, SEM, as well as the cycling performance of the cell was analyzed. The results showed that the developed semi-dry homogenization process was able to achieve a high solid content of 51.8wt%, viscosity of 4900 mPa?s and fineness of 20 μm. The viscosity of the slurry was 10 000 mPa?s after 24 h, and the slurry was basically free of gas production for 48 h. The peeling force of the anode electrode was 15 N/m, and the resistivity was 0.106 Ω/cm. The high-temperature cycle life of the 330 Wh/kg pouch cell made with high-nickel NCM (Ni9) can reach 800 cycles, which was obviously superior to that of the ordinary wet homogenizing process. Related Articles | Metrics

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Research on the removal process and mechanism of aluminum/iron impurities from wet phosphoric acid through deep extraction Youzhi DAI Ganyu ZHU Ziheng MENG Huiquan LI Chengjin XU Guoxin SUN Fang LI Lei HE Yongfang ZHANG The Chinese Journal of Process Engineering    2024, 24 (10): 1241-1250.   DOI: 10.12034/j.issn.1009-606X.224056 Abstract （225）   HTML （5）    PDF （4480KB）（104）       Knowledge map    Save The presence of impurities in phosphoric acid hinders its application in downstream processes. The development of wet-process phosphoric acid deep purification technology enables the direct preparation of phosphate-based new energy materials through a simplified process, which represents the mainstream direction for industry advancement. The solvent extraction method was employed for the extraction and separation of Al and Fe impurities in wet-process phosphoric acid. The effects of different extractants, temperature, O/A ratio, time, and extractant content on the separation efficiency of Al and Fe impurities were investigated. Optimal conditions were determined as follows: N,N-N-octyl amine di (methylene phenylphosphonic acid) (OADMPPA) extractant, extractant content of 20wt%, time of 3 min, temperature at 25℃, O/A ratio of 1:1 and 3-stage cross-flow extraction. Under these conditions, the extraction rates for Al and Fe reached 54.5% and 99.6%. Consequently, the contents of Al and Fe impurities in phosphoric acid decreased from 0.857wt% and 0.175wt% to 0.717wt% and 0.015wt%. Additionally, the MER value reduced from 9.037% to 7.227%. Further optimization of stripping process of OADMPPA extractant loaded with Al and Fe was carried out, ammonium oxalate was identified as the optimal stripping agent. The optimized stripping conditions were as follows: 25℃, 5-stage cross-flow stripping, O/A ratio of 2:1, time of 15 min, and concentration of the stripping agent at 0.2 mol/L; the stripping efficiencies for loaded extractant Al and Fe reached 96.4% and 88.3%, effectively achieving their separation from the extractant phase. Finally, the mechanism behind Al or Fe extractants was investigated by stoichiometric calculation and Fourier infrared analysis during the extraction process. It was found that during this process, one molecule of Al combined with one-and-a-half molecules of OADMPPA extractant while one molecule of Fe combined with two molecules of OADMPPA extractant; functional groups involved in these interactions included P=O and P-O-H bonds. A competitive mechanism exists in the extraction process between Al and Fe, where Fe is more easily extracted. Related Articles | Metrics

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Antibacterial properties of graphite carbon nitride materials based on piezoelectric response Wenjun MA Xiaoze WANG Jingkun ZHANG Yunfa CHEN The Chinese Journal of Process Engineering    2024, 24 (11): 1364-1374.   DOI: 10.12034/j.issn.1009-606X.224098 Abstract （220）   HTML （5）    PDF （7455KB）（57）       Knowledge map    Save The piezoelectric effect in asymmetric semiconductors has been shown to be an effective strategy to reduce carrier recombination in photocatalysis. This means that mechanical energy-induced piezoelectricity can act as a flexible automatic valve to regulate the transfer and separation of light-induced carriers in the bulk phase and on photocatalyst surfaces. Two-dimensional graphitic carbon nitride (g-C3N4) has a non-centrally symmetrical pore structure and uniform pore distribution, so it has piezoelectric response characteristics, and has received extensive attention in the field of antibacterial applications. The molecular engineering of g-C3N4 can change the piezoelectric polarization of g-C3N4 to a certain extent, which will enhance the role of the piezoelectric effect in the antimicrobial process of g-C3N4. Therefore, in this work, two-dimensional g-C3N4 materials containing hydroxyl and carboxyl oxygen-containing functional groups were synthesized by KOH with high temperature alkali treatment and KSCN calcination acid leaching, respectively. The results show that g-C3N4 still exhibits a graphite structure after the modification of the agglomeration of oxygen. The piezoresponse force microscopy (PFM) confirms the non-uniform surface potential distribution of these composite materials, and significantly improves the piezoelectric performance after the carboxyl branching. Scanning electron microscopy (SEM) show that the composite material causes a certain physical damage to the bacteria. The active oxygen (ROS) test shows that the induction effect is introduced to promote the separation of the electron-acupuncture point, which enhances the ability of the materials to capture electrons in the piezoelectric field. As a result, the captured electrons are restarted around the adsorption oxygen, generating a large amount of superoxide anion, and inducing a change in the active oxygen level within the bacteria to change, causing bacterial death. In vitro, the oxidation-induced oxidation stimulation combined with physical cutting of the antibacterial activity to Escherichia coli (E. coli) is 5log (99.999%), and the antibacterial activity against Staphylococcus aureus (S. aureus) is 4log (99.99%), which is higher than the pure g-C3N4. These findings emphasize the antibacterial potential of the carboxylated g-C3N4 material, which may be a promising candidate as an antibacterial material in the light-restricted environment. Related Articles | Metrics

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Evaporation characteristics of multiple droplets of isobutane alkylated effluent during refrigeration Xu HAN Rui ZHANG Xianghai MENG Tao ZHENG Haiyan LIU Mengxi LIU Chunming XU Zhichang LIU The Chinese Journal of Process Engineering    2024, 24 (6): 660-669.   DOI: 10.12034/j.issn.1009-606X.224001 Abstract （214）   HTML （9）    PDF （3585KB）（76）       Knowledge map    Save Isobutane alkylation catalyzed by composite ionic liquid is a new technology for the production of high quality and clean gasoline blending components. Maintaining the appropriate temperature during the alkylation reaction is crucial, and effluent cooling emerges as a pivotal measure in this regard. Currently, heat exchangers are used to cool the effluent, but there are shortcomings such as large heat exchange area requirements, high equipment cost and limited cooling effect. The presence of excess isobutane makes it possible to cool the effluent with flash spray. In order to develop a new refrigeration process for alkylated effluents, the evaporation characteristics of isobutane droplets under reduced pressure were studied. Since isobutane is a gas at room temperature and pressure, it is difficult to exist as a liquid. Therefore, a special experimental device was set up to study the evaporation process of isobutane droplets in this work. Single isobutane droplet or multiple droplets were suspended at the top of thermocouples to measure the temperature variation of each droplet, while a high-speed camera recorded the evaporation process. The effects of final pressure, ambient temperature, and droplet spacing on droplet evaporation characteristics were analyzed. The results showed that isobutane droplets underwent intense evaporation and stable evaporation phases, and the evaporation behavior of multi-droplet was similar to that of single droplet. During the stable evaporation phase, all droplets followed the classical d 2 law, and the evaporation rate of the edge and center droplets was below the single droplet. With the increase of the final pressure and the decrease of the ambient temperature, the difference between the evaporation rate of the center droplet and the single droplet gradually increased. The temperature field and vapor concentration field during droplet evaporation had a limited range of variation. When the distance between the two droplets increased to 5.48d0, the evaporation rate of the droplet gradually approached that of the single droplet. Related Articles | Metrics

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Numerical simulationon centrifugal granulation characteristics of slag optimized by gas quenching winds Xinyi ZHANG Ningwen XU Xiaoming LI Shuzhong WANG The Chinese Journal of Process Engineering    2024, 24 (5): 523-532.   DOI: 10.12034/j.issn.1009-606X.223233 Abstract （202）   HTML （5）    PDF （3932KB）（65）       Knowledge map    Save The liquid slag dry granulation and waste heat recovery technology solves the problem of waste heat loss and environmental pollution caused by the existing water quenching process of liquid slag in metallurgical industry, which plays an important role in the implementation of energy saving and emission reduction strategy. In order to improve the resource utilization of slag pellets and reduce the equipment investment, the addition of auxiliary gas quenching wind at the edge of the pelletizer is proposed to enhance the palletizations effect and improve the waste heat recovery efficiency. However, the mechanism of the effect of gas quenching wind on centrifugal granulation and the influence pattern are still unclear in the current study. A three-dimensional granulation model with gas quenching wind was established using the SST k-ω turbulence model. And the effects of gas quenching wind on the granulation effect, the flight velocity of waste particles and the cooling effect of rotor cup were investigated by using the VOF method. The changing rule of the horizontal flight speed of liquid droplets under different gas quenching wind conditions was investigated to provide reference basis for optimizing the flight trajectory of liquid droplets and the spatial design of granulation silo. Findings indicated that while increasing air volume shifted particle size distribution to larger ranges, it benefited the slag particles' sphericity. The gas quenching wind effectively induced particle fragmentation within the air flow range of 4~6 m3/h, with enhanced cooling effects when air flow surpassed 2 m3/h. When selecting the air flow, the air flow of 1 m3/h can be selected when considering the granulation effect and flight speed only, and the flow of 2 m3/h was the best when considering the cooling effect comprehensively. Using a ring slit for air venting resulted in the smallest average diameter of slag particles, lower wall temperatures near the rotating cup, moderate flight speed, and superior sphericity compared to a state without gas quenching wind. Related Articles | Metrics

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Research on Cu-assisted leaching process of zinc leaching residue and zinc calcine Limin ZHANG Yunyan WANG Weiping LIU Xiaobo MIN Wenjun LIN Yong KE The Chinese Journal of Process Engineering    2024, 24 (5): 558-565.   DOI: 10.12034/j.issn.1009-606X.223327 Abstract （200）   HTML （3）    PDF （1157KB）（79）       Knowledge map    Save To reduce the amount of zinc leaching residue and improve the metal recycling rate in the traditional zinc smelting process, a Cu-assisted reductive leaching process of zinc leaching residue and zinc calcine was proposed in this study. In the presence of sufficient copper powder, effect of factors including sulfuric acid concentration, liquid-solid ratio, leaching temperature, and the amount of H2SO4 on the zinc leaching efficiency, the residual rate of the solid, and the residual amount of H2SO4 for zinc leaching residue and zinc calcine was investigated. The results of leaching experiment showed that for zinc leaching residue, the zinc leaching efficiency was enhanced from 32.82% to 92.82% assisted by copper, compared to the pure acid leaching process (100 g/L H2SO4, 20 mL/g, 60℃). The residual rate of the solid was decreased from 62.34wt% to 25.20wt%. Values of pH of the leaching solution were increased from 0.12 to 0.36. For zinc calcine, the zinc leaching efficiency was enhanced from 86.52% to 98.82% assisted by copper, compared to the pure acid leaching process (200 g/L H2SO4, 10 mL/g, 60℃). The residual rate of the solid was decreased from 26.56wt% to 6.28wt%. Values of pH of the leaching solution were increased from 0 to 0.19. The least concentration of the residual H2SO4 was 25~26 g/L for sufficient extraction of zinc. The Cu-assisted leaching process has advantages in metal recycling, residue reduction, and low concentration of the residual H2SO4. It supplies a new idea about in situ treatment of zinc leaching residue in zinc smelters. Related Articles | Metrics

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Removal performance and mechanism of humic acid by persulfate activated with ultraviolet light combined with magnetic ion exchange resin Wenlong WU Yuchen GAO Jinwei ZHANG Ling LI Yan LI Yuchen ZENG Chun YANG Jiapeng LU Lei DING The Chinese Journal of Process Engineering    2024, 24 (5): 566-579.   DOI: 10.12034/j.issn.1009-606X.223268 Abstract （197）   HTML （4）    PDF （5338KB）（132）       Knowledge map    Save Humic acid (HA) in water was removed by activating persulfate with ultraviolet light combined with magnetic ion exchange resin. The removal efficiency of HA, the environmental factors affecting the removal of HA, the generation mechanism of active oxidizing species and the removal mechanism of HA in the ultraviolet light/persulfate/magnetic ion exchange resin (UV/PMS/MIEX) system were explored. The UV/PMS/MIEX synergistic system had a significant removal efficiency for HA in water, and the removal efficiency reached 91.71% after 120 minutes of reaction. The increase in resin dosage and temperature promoted HA removal, and increasing the concentration of persulfate could improve the removal efficiency of HA to a certain extent, but the effect of solution pH on the removal of HA was not obvious. In this system, the removal of HA was mainly through oxidation, and the adsorption effect WAs not significant. The iron oxides on the surface of the resin, the oxygen-containing functional groups and the addition of ultraviolet rays could effectively activate persulfate to produce various active oxidizing species such as ?OH, SO4?-, O2?-, and 1O2. In this system, HA fractions were degraded by the radical and non-radical pathways, and the activation mainly occurs through the radical pathway. Based on the characterization of N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and X-ray photoelectron spectroscopy before and after the reaction, it can be found that the magnetic ion exchange resin exhibits good reusability and stability, and can effectively adsorb and remove various by-products in the system. This study provides a new method for HA removal in water, and the constructed oxidation system shows a good application prospect. Related Articles | Metrics

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Process simulation of pressure swing adsorption technology optimization based on low concentration methane enrichment Mingjun QIU Xiaomin LI Hua SHANG Jiangfeng YANG Jinping LI The Chinese Journal of Process Engineering    2024, 24 (8): 884-893.   DOI: 10.12034/j.issn.1009-606X.224042 Abstract （196）   HTML （3）    PDF （4718KB）（115）       Knowledge map    Save Methane enrichment is a necessary measure to develop and utilize low concentration coalbed methane. Among many separation technologies, pressure swing adsorption technology has become the most widely used technology in recent years due to its advantages of low energy consumption and low cost. In order to better realize the methane enrichment effect (purity and recovery), it is necessary to study the relationship between the adsorbent and the pressure swing adsorption process, that is, to select a suitable pressure swing adsorption process for the adsorbent. This work uses Aspen adsorption process simulation software to study two different types of adsorbents (N2 selective adsorbent MIL-100(Cr) and CH4 selective adsorbent Silicalite-1) in common and optimal vacuum pressure swing adsorption (adding buffer tank). Simulation results shows that the optimal vacuum pressure swing adsorption process can effectively improve the CH4 recovery, and MIL-100(Cr) has a significantly better recovery improvement effect compared with Silicalite-1. However, when the CH4 content of the coalbed methane is less than 30%, CH4 recovery of 100% can be achieved by using Silicalite-1 adsorbent in the optimal vacuum pressure swing adsorption process. In the actual process of enriching coalbed methane, methane purity and recovery are very important indicators. Therefore, the single cycle efficiency index is proposed to comprehensively evaluate the efficiency of the methane enrichment process. The results show that compared with the common vacuum pressure swing adsorption process, the optimal vacuum pressure swing adsorption process using MIL-100(Cr) adsorbent has a single cycle efficiency improvement of more than 30 percentage point, while that of Silicalite-1 adsorbent even slightly decline 1 percentage point. Comparative analysis shows that the common vacuum pressure swing adsorption process is suitable for Silicalite-1 adsorbent, and the optimal vacuum pressure swing adsorption process with buffer tank is more suitable for MIL-100(Cr) adsorbent. Related Articles | Metrics

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CFD-DEM-based simulation of Ca(OH)2/CaO thermochemical energy storage process in a novel baffled moving bed reactor Jianyi CHEN Min XU Cang TONG Caifeng HUANG Xiulan HUAI The Chinese Journal of Process Engineering    2024, 24 (8): 894-903.   DOI: 10.12034/j.issn.1009-606X.224048 Abstract （196）   HTML （7）    PDF （11216KB）（111）       Knowledge map    Save The Ca(OH)2/CaO thermochemical energy storage technology has garnered significant attention owing to its attractive features of high energy storage density and cost-effectiveness, positioning it as a promising advancement in energy storage methodologies. Nonetheless, traditional fixed bed reactors may pose challenges with their potential to yield a diminished heat storage rate for Ca(OH)2 particles. To address the challenge of low heat storage rate in conventional fixed bed reactor, a novel baffled moving bed structure is introduced. The heat storage process of Ca(OH)2 particles in the moving reactor bed under the influence of gravity is studied by using the coupled method of computational fluid dynamics and discrete element method (CFD-DEM). Compared to porous media models, CFD-DEM offers a closer approximation to real flow conditions and provides detailed physical information at the particle scale. The results indicate that the moving bed achieves a higher heat storage rate compared to its fixed bed counterpart under identical conditions, providing evidence for the feasibility of employing a moving bed as a thermochemical reactor. The introduction of baffles in the moving bed is able to extend the particle residence time in the reactor, consequently amplifying both the heat storage rate and energy storage efficiency. However, it concurrently results in an increased pressure drop on the gas side. The simulations under various inlet conditions reveal that elevating the gas temperature at the reactor inlet positively impacts the heat storage rate. Within specific ranges, an increase in the inlet gas flow rate can improve the energy storage rate, albeit with caution against excessively high flow rates that could induce blockages and diminish the overall heat storage rate. Notably, the inlet solid flow rate exhibits an optimum value, maximizing the comprehensive heat storage rate of the reaction bed. Related Articles | Metrics

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A structured assessment method of human error probability for chemical systems Qianlin WANG Shicheng CHEN Xiaodong HU Jianwen ZHANG Liangchao CHEN Jinghai LI Zhan DOU The Chinese Journal of Process Engineering    2024, 24 (5): 609-617.   DOI: 10.12034/j.issn.1009-606X.223251 Abstract （195）   HTML （5）    PDF （974KB）（74）       Knowledge map    Save At present, the essential reliability of chemical equipment has been increasingly improved with a development of automation and information technology, and human error has become the main factor over chemical accidents. Hence it is necessary to conduct human reliability analysis (HRA) on chemical systems to ensure their safe and stable operations. However, the chemical systems have a high non-linearity and complex coupling. The existing HRA technologies cannot be directly applied on them, and the effectiveness and accuracy of analysis results are poor. Therefore, this work proposes a structured assessment method of human error probability for chemical systems. This method particularly combines the human-hazard and operability analysis (human-HAZOP) with Bayesian network (BN). Firstly, according to the operation manual, process flow diagram, and other information of a chemical system, the tasks are summarized for human-HAZOP and further subdivided into several operation steps and behaviors. Secondly, meaningful deviations are selected using the operation behaviors and guide words. Accordingly, the potential causes, possible consequences, existing measures, and suggested measures are analyzed to form a structured human-HAZOP report for this chemical system. Thirdly, based on the human-HAZOP results, the potential causes and possible consequences are considered as leaf nodes and root nodes, respectively. A structured BN model is finally established to calculate the human error probability in the chemical system. The esterification reaction of one methyl-acrylate virtual simulation factory is taken as a test case. The probability of human error for the esterification reaction is calculated to be 0.0004 and the main human error behavior is maintenance staff stealing work omission of maintenance staff. Traditional CREAM analysis of this chemical system results in human error probability results of 0.0001 to 0.01. Results show that this structured method can effectively and accurately assess the human error probability of chemical systems in comparison with the traditional CREAM. Related Articles | Metrics

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Numerical simulation of low nitrogen combustion in CFB boiler based on post-combustion technology Xiaojie LIU Shunsheng XU Runjuan KONG Jianbo LIU The Chinese Journal of Process Engineering    2024, 24 (8): 914-925.   DOI: 10.12034/j.issn.1009-606X.224031 Abstract （193）   HTML （3）    PDF （6337KB）（127）       Knowledge map    Save Severe environmental protection policies have put forward higher requirements for coal combustion power generation. As a mature clean coal power generation technology, the circulating fluidized bed (CFB) boiler has broad research prospects. CFB post-combustion technology is a new type of fluidized bed out-of-stock technology that has been applied to 75 t/h CFB coal slime boilers and achieved ultra-low NOx emissions. Exploring the feasibility and effectiveness of post-combustion technology in larger-scale CFB boilers has become the focus of future research. In this study, a numerical model of the flow and combustion of a 150 t/h CFB boiler in full-loop was established using the method of computational particle fluid dynamics (CPFD). The availability of the model was verified by comparing it with industrial data. The effects of excess air ratio in CFB, primary air ratio, and ratio of upper and lower secondary air on furnace combustion and NOx emissions were studied after the addition of post-combustion technology. The results showed that there was a typical core-circulation structure in the furnace. On the one hand, oxygen-poor combustion inhibited NOx generation, and on the other hand, the high CO concentration zone caused by combustion was also conducive to NOx reduction. After the use of post-combustion technology, the reduction atmosphere of the furnace increased, and the NOx emission reduced from 174.6 mg/m3 to 114.2 mg/m3. Combined with the air stage, optimizing the primary air ratio and the ratio of upper and lower secondary air, CO emission increased from 3.4×10-5 in the basic working condition to 7.1×10-5, the combustion efficiency was slightly reduced, and NOx emission was further reduced. Under optimal working conditions, NOx emission decreased from 174.6 mg/m3 to 76.3 mg/m3, NOx emission decreased by 56.3%, and the furnace temperature distribution was uniform. The research results can provide valuable theoretical insights for the application of post-combustion technology in CFB boilers and provide support for its practical application. Related Articles | Metrics

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Experimental analysis of enhanced absorption of CO2 by NaOH solution in Kenics static mixer Yanfang YU Henglei YU Huibo MENG Puyu ZHANG The Chinese Journal of Process Engineering    2024, 24 (10): 1149-1157.   DOI: 10.12034/j.issn.1009-606X.224110 Abstract （193）   HTML （7）    PDF （2644KB）（99）       Knowledge map    Save The carbon peaking and carbon neutrality goals has been concerned, and the current global warming problem caused by excessive carbon dioxide emissions is very serious. In order to alleviate global ecological problems and better achieve the dual-carbon strategy, the research and development of carbon dioxide capture technology is indispensable. In order to enrich the application of static mixers in the field of carbon dioxide absorption, Kenics static mixer (KSM) was used as the enhanced reaction equipment. Based on sodium hydroxide aqueous solution and carbon dioxide (NaOH-CO2) system, the absorption efficiency of carbon dioxide concentration in the range of 25%~33% volume concentration was analyzed using KSM and empty tube structures under different sampling positions and gas-liquid flow rates. The absorption efficiency of carbon dioxide was measured by automatic potentiometric titration. The absorption performance of the KSM structure was compared with that of the empty pipe. The results showed that the maximum absorption efficiency of CO2 in KSM was 72.3% higher than that of the empty pipe. The absorption efficiency of CO2 decreased with the increase of the liquid phase flow rate (QL) at a certain gas phase flow rate (QG) in the empty pipe structure. In contrast, the absorption efficiency of CO2 increased with the increase of QL when KSM elements were installed in the pipe. The volume energy dissipation rate (ε) of KSM structure was analyzed, and it was concluded that the minimum ε was 4.85 m2/s3 when the CO2 absorption efficiency reached more than 90%. The ε increased by 14.7% when total gas-liquid flow rate (QT) varied from 20 L/min to 22 L/min at QG=6 L/min from the first sampling point (Z1) to second sampling point (Z2) in the pipeline. However, the ε increased by 7.83% when QT changed in the same range at QL=14 L/min. The results showed that the change of ε was more affected by QL than QG, and the system energy consumption and reaction were more obvious from Z1 to Z2 in the pipeline. When the gas superficial velocity (UG) was constant, the Darcy friction coefficient (f) decreased with the increase of the liquid superficial velocity (UL), and when the UL was constant, the f decreased with the increase of the UG. The empirical correlation among the UG, UL, and f was obtained by fitting the experimental data with R2=0.999, the correlation deviation ranged from -0.88% to 0.82%. Related Articles | Metrics

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Microstructure and properties analysis of Microstructure and properties analysis of welded joint of 22MnB5/QStE550TM dissimilar steel Ming ZHANG Leilei ZHOU Enrong LIANG Zhigang ZHU Pengyan ZHANG The Chinese Journal of Process Engineering    2024, 24 (7): 863-874.   DOI: 10.12034/j.issn.1009-606X.223321 Abstract （192）   HTML （5）    PDF （3225KB）（74）       Knowledge map    Save In the experiment, different thickness of 22MnB5 steel with 1.8 mm thickness and QStE550TM steel with 2 mm thickness are welded by TIG welding. The microstructure of the characteristic area of the welded joint of different steel is observed by optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The mechanical properties of dissimilar steel welded joints are analyzed by universal mechanical testing machine and Vickers hardness tester. The experimental results show that the microstructure of the heat affected zone on the QStE550TM side is granular bainite, the microstructure of the weld area and the heat affected zone on the 22MnB5 side is lath bainite, and part of the oxide inclusion in the heat affected zone on the 22MnB5 side induces the formation of acicular ferrite. The average grain size in the weld area is 4 μm, and the proportion of grain boundaries with large angle in the weld area is about 53%. The second phase Ni-Cr-Fe solid solution was found in the characteristic region of the dissimilar steel welded joint. The average tensile strength of the two groups of tensile samples is 660.5 MPa. The highest hardness area of the welded joint is 22MnB5 base metal, and the lowest hardness area is QStE550TM side heat affected zone. There is carbon migration in the heterogeneous steel joint. A carburized layer of about 43 μm appears near the fusion interface of 22MnB5 side, and a decarburized layer of about 35 μm appears in the heat affected zone of QStE550TM side. However, combined with the analysis of the mechanical properties of the dissimilar steel welded joint, the carbon migration phenomenon of the welded joint has no obvious effect on the mechanical properties. Related Articles | Metrics

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Advances in wet particle size-grading technologies and precise grading of aluminum hydroxide Jianqing Pi Mingli WANG Ruyi YANG Haidong ZHANG Xiaona REN Qingshan HUANG Ping LI The Chinese Journal of Process Engineering    2024, 24 (6): 647-659.   DOI: 10.12034/j.issn.1009-606X.223331 Abstract （192）   HTML （8）    PDF （4811KB）（139）       Knowledge map    Save With the booming development of the electrolytic aluminum industry, both modern large-scale prebaked aluminum reduction cells and dry purification technology require sandy alumina as the production raw material. However, domestic alumina enterprises mainly produce intermediate or "quasi-sand" alumina, and the particle size changes periodically. The product quality differs significantly from the world's advanced level, mainly due to differences in raw materials and substandard aluminum hydroxide particle screening technologies in the prior art. Therefore, it is urgent to develop a high-precision and high-efficiency wet particle classification device for aluminum hydroxide to produce high-quality sandy alumina with large and narrow particle size distribution (+80 μm≥90%, -45 μm<8%). The commonly employed and large-scale application of wet particle size-grading technologies in domestic and foreign countries are first reviewed. The performance of hydraulic classification, wet screening, and some new coupling classification technologies are analyzed. Then, a new particle grading method of fluidization followed by screening for precise grading of aluminum hydroxide particles is proposed by combining hydraulic classification and sieve screening. Finally, a small-scale grading device (3.3 m3/h) capable of achieving large-scale continuous production is developed and passed the verification of on-site production siding in the production enterprise. This new type of precise particle classification technology is not only expected to realize energy conservation and emission reduction, transformation and upgrading, reduction of production costs, and significant economic benefits in the alumina industry but also promote the rapid development of mineral processing and fine powder industries, having some important and practical application and promotion values. Related Articles | Metrics

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Recovery of metal aluminum by electrolysis of AlCl3-NaCl-LiCl-KCl molten salt Yahui AN Fengguo LIU Aimin LIU Zhongning SHI Zhaowen WANG The Chinese Journal of Process Engineering    2024, 24 (7): 825-832.   DOI: 10.12034/j.issn.1009-606X.223325 Abstract （192）   HTML （8）    PDF （6783KB）（44）       Knowledge map    Save Over the past few decades, aluminium alloys have been used in a large number of applications in packaging, transport, aerospace and other areas, making them the second most important metallic material after steel. Because of their good corrosion resistance, aluminum alloys can be recycled after reaching the end of their useful life. The recycling of aluminum alloys has the double important significance of saving resources and environmental protection. The traditional cryolite electrolytic alumina process consumes a lot of energy and releases a lot of greenhouse gases. Remelting and recycling of end-of-life aluminum alloys can reduce energy consumption and carbon emissions, but this method affects the purity of the recycled aluminum. Recycling of scrap aluminum by molten salt electrolysis not only reduces energy consumption and carbon emissions, but also improves the purity of the recycled aluminum. In this work, AlCl3-NaCl-LiCl-KCl was used as the electrolyte for aluminum deposition on pure aluminum sheet with scrap aluminum alloy as the anode. The effect of experimental conditions such as current density, electrolysis temperature, and electrolysis time on the recovered metallic aluminum products were investigated, and the electrochemical mechanism of aluminum recovery in AlCl3-NaCl-LiCl-KCl molten salt was analyzed. It was shown that the current efficiency in scrap aluminum alloy could reach 97.3% and the purity of aluminum obtained was about 99.4wt% under the conditions of electrolysis temperature of 100℃, current density of 30 mA/cm2, and electrolysis for 3 h. The cyclic voltammetry curve indicated that only aluminum was involved in the reaction process, and the deposition potential of aluminum was about -0.3 V (vs. Al), and the scrap aluminum alloy dissolved under the action of the current and reacted with AlCl4- in the electrolyte to form Al2Cl7-, and Al2Cl7- near the cathode gained electrons to form an aluminum deposition layer on the cathode surface. Related Articles | Metrics

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Process optimization and crystallization kinetics for preparation of nesquehonite by impinging stream-coprecipitation technology Jianwei ZHANG Xianhong ZOU Xin DONG Ying FENG The Chinese Journal of Process Engineering    2024, 24 (5): 533-545.   DOI: 10.12034/j.issn.1009-606X.223240 Abstract （191）   HTML （2）    PDF （8499KB）（71）       Knowledge map    Save Impinging stream is a technique to enhance heat and mass transfer in process engineering. Due to the characteristics of its high and uniform supersaturation, it is widely used in powder preparation. Nesquehonite (MgCO3?3H2O) can be used to combine with materials and increase the strength and toughness of materials because of its special rod-like structure. In this work, MgCO3?3H2O crystal was prepared from magnesium chloride and sodium carbonate by a new impinging stream technology combined with co-precipitation method, and the preparation process conditions and crystallization kinetics of MgCO3?3H2O were studied. The effects of reactant concentration c, reaction temperature T, cyclic impact flow rate Q and cyclic impact time t on the crystal morphology and structure of MgCO3?3H2O were discussed by taking the aspect ratio of rod-like MgCO3?3H2O as the index. The optimal conditions were as follows: the reactant concentration was 0.25 mol/L, the reaction temperature was 50℃, the cyclic impact flow rate was 500 L/h, and the cyclic impact time was 50 min. Under these conditions, the MgCO3?3H2O crystal with the aspect ratio of 20 and an average crystal length of 57.3 μm can be obtained. The particle size distribution data under different conditions were measured by laser particle size meter, and the crystal nucleus number density, growth rate and nucleation rate of the product were analyzed according to the population balance model. Under the optimal conditions, the nucleation rate of the crystals was 2.061×106 #/(mL?min) and the growth rate was 0.148 μm/min. The nucleation and growth kinetic equations of each factor in the system of impinging stream-coprecipitation reaction were obtained, and the sensitivity coefficient i of each factor on crystal growth was determined. iQ<iT<0<it<ic is the relationship of sensitivity coefficients obtained by each influencing factor. Cyclic impact flow rate and reaction temperature can promote crystal growth. Related Articles | Metrics

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Experimental study on optimization of direct-reverse flotation of a phosphate ore by response surface methodology Shengdong ZHANG Zhongbao HUA Yu ZHAO Xiong TONG Xian XIE The Chinese Journal of Process Engineering    2024, 24 (5): 546-557.   DOI: 10.12034/j.issn.1009-606X.223291 Abstract （183）   HTML （4）    PDF （5990KB）（71）       Knowledge map    Save The contents of P2O5, SiO2 and CaO in a phosphate mine in Yunnan are 18.59%, 37.37%, and 27.55%, respectively. It can be seen that this ore belongs to silica-calcareous collophanite. According to the properties and characteristics of this ore, the flotation test was carried out by using the direct-reverse flotation flow. Firstly, the optimal dosage of each reagent was determined by a single factor condition test. On this basis, the response surface methodology was used to further optimize the dosage of three kinds of regulators in positive flotation. Finally, based on the results of the single factor condition test and response surface methodology optimization, closed-circuit flotation test was carried out. The results of the single factor condition test showed that the optimal dosage of Na2CO3, Na2SiO3, YP6-1 in direct flotation, YP6-1 in reverse flotation, modified starch DZ, H2SO4 and H3PO4 were determined to be 3000, 1500, 2400, 600, 700, 5000, and 4000 g/t, respectively. Under the optimum dosage of these reagents, phosphorus concentrate with P2O5 grade and recovery of 30.19% and 73.06% can be obtained by a direct-reverse flotation. The response surface optimization experiment revealed that the optimal dosages of Na2CO3, Na2SiO3, and modified starch DZ in direct flotation were 3016.15, 1986.72, and 877.33 g/t, respectively. Actual flotation tests conducted under these conditions resulted in a concentrate with a P2O5 grade of 30.08% and a recovery of 75.81%, which was found to be in good agreement with the predicted results. Compared with the results of the traditional single factor condition test, the recovery can be increased by 2.75 percentage points while maintaining the same grade by using the response surface methodology. Finally, the closed-circuit flotation test was carried out based on the result of the single factor condition test and response surface optimization. The phosphorus concentrate with P2O5 grade of 32.07% and recovery of 72.83% was obtained, which indicates that a good flotation effect of the refractory fine collophanite has achieved. Related Articles | Metrics

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A thermal analysis kinetics method under flowing conditions based on distributed temperature sensing Yang SHEN Qiyue XU Shuliang YE The Chinese Journal of Process Engineering    2024, 24 (7): 783-792.   DOI: 10.12034/j.issn.1009-606X.223348 Abstract （182）   HTML （2）    PDF （4638KB）（49）       Knowledge map    Save Addressing the needs for risk assessment and process optimization in continuous flow production, research was conducted to explore thermodynamic and kinetic calculation methods under flow conditions. By analyzing the thermal balance and material equilibrium of tubular reactors, a thermal analysis kinetics method applicable to flow conditions was designed. Subsequently, a continuous flow reaction experimental platform was constructed based on measurement principles for validation. Initially, temperature sensors distributed at various positions within the pipeline were employed to capture the temperature distribution during the experimental process. The equivalent overall heat transfer coefficient of the reaction pipeline was calibrated, and used in conjunction with segmented temperature distributions to calculate the enthalpy of the reaction. Subsequently, given the tendency to overlook temperature distribution in kinetic analyses, the study integrated calorimetric results and reactor models to compute kinetic parameters. The practicality of this approach was studied using the hydrolysis reaction of ethyl acetate and sodium hydroxide as an example. During the experiments, adjusting flow rates was employed to locate the peak temperature distribution, thereby enhancing the accuracy of calculated reaction enthalpy. The experimental outcomes revealed that under suitable flow conditions, the calculated reaction enthalpy closely matched results from batch experiments and established literature values. Moreover, the flow calorimetric method exhibited higher experimental efficiency, lower liquid holdup, and increased safety during the experiment. The kinetic analysis results were in close alignment with literature values, showing a relative error of less than 3% in the activation energy calculations. Combining calorimetric results with kinetic parameters allowed the use of reactor models to predict temperature distributions under varying conditions, demonstrating a close correlation with measured values. This serves as valuable guidance for subsequent risk assessments and process optimizations in the realm of reaction evaluation and procedural enhancements. Related Articles | Metrics

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Optimization of lentivirus production process in a fixed-bed bioreactor Siran TAO Jun CHENG Lei CAO Yan ZHOU Wensong TAN The Chinese Journal of Process Engineering    2024, 24 (6): 734-745.   DOI: 10.12034/j.issn.1009-606X.223245 Abstract （181）   HTML （5）    PDF （2489KB）（58）       Knowledge map    Save The lentivirus vectors can stably integrate exogenous genes into the genomes of various cells, making it useful in gene therapy. Among various bioreactors, fixed-bed bioreactors are increasingly used to scale-up the cultivation of adherent cells for the manufacture of lentivirus through plasmid transient transfection. In the fixed-bed bioreactor the production of lentivirus vectors can be heavily affected by various operating parameters. This study aims to optimize the transfection conditions and cell culture parameters during the production of lentivirus, and then validate optimized process conditions in China's domestically-made fixed-bed reactor. The results showed that during the plasmid transfection, the transfection efficiency could be significantly improved in the optimized conditions where the mass ratio of PEI to DNA was 2:1, the DNA concentration during transfection was 2 μg/mL, and the transfection time was 6 hours, respectively. The mass ratio of PEI to DNA was the key factor to the success of transfection. When the ratio of PEI to DNA was below 2:1, the transfection efficiency noticeably reduced and exogenous gene could not be expressed in the HEK293T cells. However, DNA concentration during mixing and mixing time have little effect on transfection efficiency, which mainly affects the expression of exogenous genes in cells. When the HEK293T cells were cultured in shaking bottles based on PET nonwoven fabric, the cells were evenly distributed on the surface of the scaffold and quickly entered the exponential growth phase at a high inoculation density of 5.0×104 cells/cm2. The cell densities that are too high or too low during transfection are not conducive to lentivirus production, and a high lentivirus titer can be obtained when the cell density is 1.0×106 cells/cm2. After process optimization, the lentivirus yield reached 2.4×1010 TU in the fixed-bed bioreactor with an surface of 2.0 m2. The results of this study can provide data support for the development and establishment of the production of lentivirus vectors based on a fixed-bed bioreactor. Related Articles | Metrics

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Analysis of new blade structure and mixing characteristics of horizontal mixer Shen LI Linsheng XIE Guo LI Yu WANG Yulu MA The Chinese Journal of Process Engineering    2024, 24 (8): 875-883.   DOI: 10.12034/j.issn.1009-606X.223364 Abstract （180）   HTML （8）    PDF （3092KB）（127）       Knowledge map    Save The dynamic mixer is the mainstream of today's mixing equipment, and the mixing effect not only affects the production efficiency of the equipment, but also directly determines the performance of the final product. Among them, the structure of the mixing element in the dynamic mixer directly determines its mixing effect on the processed material. Due to the complex structure of the dynamic kneading mixer, the theoretical research on its mixing characteristics is very limited. In this work, the blade structure of the horizontal mixer was optimized and improved, and the structure design of the main and auxiliary blades was adopted to improve the mixing effect of the mixer. By constructing the three-dimensional model and finite element model of the mixer with a new type of blade structure, the mixing characteristics of the mixer were investigated by means of numerical simulation using the computational fluid dynamics software Polyflow, and the influence of blade speed on the mixing performance of the mixer was analyzed. Mixing index, separation scale, average tensile rate, logarithmic tensile rate, and cumulative depolymerization power were used to characterize the dispersion and distribution mixing ability of the mixer, and the accuracy of numerical simulation results was verified by visual experiments. The results of simulation and experiment showed that the simulation results were consistent with the visual experiment results. The material flow type in the mixer with the new blade structure was shear flow, accounting for about 85%. The average tensile rate and average logarithmic tensile rate in the flow field were always positive, indicating that the mixer had good distribution and dispersion mixing ability. The increase of blade speed had little influence on the flow type of materials in the flow field, but can effectively improve the performance of distributed mixing and dispersed mixing of the mixer. When the blade speed increased from 30 r/min to 120 r/min, the average separation scale of the mixer's transverse distribution mixing decreased by 50%, and the average tensile rate increased by 300%. The average cumulative depolymerization work increased by 1500%. Related Articles | Metrics

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Preparation of high-purity copper by electrochemical recovery of waste cupronickel in choline chloride-glycol deep eutectic solvent Hongda LI Juanjian RU Mingqiang CHENG The Chinese Journal of Process Engineering    2024, 24 (10): 1222-1229.   DOI: 10.12034/j.issn.1009-606X.224041 Abstract （180）   HTML （3）    PDF （1783KB）（27）       Knowledge map    Save Waste cupronickel is widely used in many fields, with the increasing demand and consumption of waste cupronickel, a large amount of waste copper alloy has been produced. Although the traditional wet process can remove some insoluble impurities and the working conditions are superior, the process is long and the energy consumption is high. Therefore, this work high-purity copper (Cu) was recovered from waste cupronickel by electrolysis separation at 363 K and 0.1~0.5 V cell voltage in choline chloride-glycol deep eutectic solvent (ChCl-EG DES) with the molar ratio of 1:2 as an electrolyte, waste cupronickel as an anode, and titanium sheet as a cathode. Electrochemical tests exhibited that Cu can be dissolved as monovalent Cu(I) into ChCl-EG DES, and the reduction of Cu(I) at the concentration range of 0.5~2.5 mol/L CuCl was a quasi-reversible process. The calculated Ea of the anode dissolution process was only about 28.361 kJ/mol, indicating that the dissolution process of Cu in ChCl-EG DES was controlled by diffusion. The anode polarization curve implied that Sn was dissolved into the solution first, while the dissolution potential of Ni and Fe was similar to that of Cu, and they were entered into anode slime. The electrolysis experiment showed that when the cell voltage increased, both the DC power consumption and the current efficiency increase accordingly. When the cell voltage was at 0.5 V, the current efficiency of electrochemical recovery of waste cupronickel was as high as 97.20%, and the DC power consumption was 216.94 kWh/t. At higher cell voltage (0.3~0.5 V), the morphology of cathode copper was irregular mass with a particle size of 30~50 μm, and the purity of copper can be obtained at the cathode at 0.4 V cell voltage was as high as 99.95wt%. Related Articles | Metrics

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Effect of experimental conditions on the impurity content in Ni0.8Co0.1Mn0.1(OH)2 synthesized by co-precipitation Qianying HAN Li YANG Haoliang WANG Rizhi CHEN Jingcai CHENG Chao YANG The Chinese Journal of Process Engineering    2024, 24 (11): 1344-1353.   DOI: 10.12034/j.issn.1009-606X.224102 Abstract （175）   HTML （3）    PDF （9216KB）（62）       Knowledge map    Save During the synthesis of precursor materials for ternary lithium battery cathodes via co-precipitation, the presence of impurities such as iron, aluminum, magnesium, copper, and sulfur can adversely affect the electrochemical performance of the final cathode materials. The existing studies are lack in mechanism analysis of the influence of coprecipitation conditions on the inclusion of impurities in precursor particles. The impurities in Ni0.8Co0.1Mn0.1(OH)2 synthesized via co-precipitation have been analyzed using multiple characterization methods. The impurities primarily consist of sodium, magnesium, calcium, iron, copper, zinc, aluminum, and sulfur, and may be distributed within the crystal lattice, interstitial sites, or on the surface of the precursor particles. The results indicate that the concentration of ammonia has a significant effect on the contents of iron, copper, zinc, and aluminum. The precursor synthesized under the condition of pH 11.7 is colloidal and has a larger specific surface area, which adsorbs the highest amounts of sodium and sulfur, being 28134.62 and 12898.50 μg/g, respectively. The variation in stirring speed has a certain effect on the distribution of sulfur content. Optimizing the process conditions of ternary precursor co-precipitation process is of great significance to control the impurity content in the precursor and improve the electrochemical performance and safety of the final ternary cathode material. Related Articles | Metrics

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Application research based on optimization of key parameters in heavy gas dispersion model Jiamei YIN Haiyan LIU Zechun LIU Wei WU Juanxia HE The Chinese Journal of Process Engineering    2024, 24 (6): 681-691.   DOI: 10.12034/j.issn.1009-606X.223272 Abstract （175）   HTML （7）    PDF （3264KB）（56）       Knowledge map    Save Leakage accidents from storage tanks with dangerous chemicals may cause catastrophic consequences. For the purpose of improving the predicted accuracy of heavy gas dispersion during release incidents, the dispersion coefficients were improved in SLAB to obtain the SLAB-D model. Then SLAB-MD model was developed by integrating the optimization algorithms of dispersion coefficients based on the SLAB-M. The Jack Rabbit II (Trials 1, 7, and 9) liquid chlorine leakage experiments were employed as the dataset to evaluate and validate models' performance. The outcomes revealed that the four models' performances were ranked as SLAB-MD>SLAB-D>SLAB-M>SLAB, and the statistical performance measurements (SPMs) of the SLAB-MD model were close to the ideal values, among which the mean relative bias (MRB), geometric mean (MG), mean relative square error (MRSE), geometric variance (VG), and factor of 2 (FAC2) were 0.27, 1.34, 0.18, 1.24, and 0.93, respectively, which proved that SLAB-MD was excellent in accurately predicting the dispersion of heavy gas leaks. Finally, the model was used to analyze three typical heavy gas leakage and dispersion accidents at domestic and international, which obtained key information such as heavy gas concentration distribution and three-dimensional concentration surface. Additionally, the range of potential casualties was predicted based on the protective action criteria values (PACs). The potential impact zones at the downwind distance, including fatalities, serious injuries, and minor injuries, were 0.15, 1.75, and 7.6 km2, 0.22, 1.98, and 7.03 km2, and 0.12×10-3, 0.29×10-3, and 0.88×10-3 km2 in the context of liquid chlorine continuous release, liquid chlorine instantaneous leakage, and vinyl chloride continuous discharge, respectively. At sensitive points, the longest escape time was 28 min for liquid chlorine continuous leakage accident, and aftereffect time was 40 min for vinyl chloride continuous release accident. In summary, these predictions provide critical information and effective technical guidance that can be used for emergency response planning and management involving hazardous chemical material spills. Related Articles | Metrics