Most Read articles

Published in last 1 year |  In last 2 years |  In last 3 years |  All

In last 3 years

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

CO2 methanation: recent advances in catalyst development and reaction mechanistic study Junbo TIAN Fangna GU Fabing SU Zhanguo ZHANG Guangwen XU The Chinese Journal of Process Engineering    2023, 23 (3): 375-395.   DOI: 10.12034/j.issn.1009-606X.222027 Abstract （1561）   HTML （72）    PDF （12772KB）（922）       Knowledge map    Save Choosing a suitable approach for CO2 utilization is crucial to achieving carbon neutrality and carbon peak goals as early as possible. Synthesis of synthetic natural gas (SNG) by methanation of CO2 using hydrogen produced from renewable energy is widely regarded as an efficient and promising carbon capture and utilization technology, which is expected to realize carbon recycling. Considering the importance of CO2 methanation, we provide a systematic review of the latest studies. Firstly, the effect of different reaction conditions on CO2 methanation is introduced from the perspective of thermodynamics. Secondly, the research progress of CO2 methanation catalysts is reviewed from four aspects: active metal, support, preparation method, and assistive technology. In detail, the active components are classified into cheap metal-based (Ni, Fe, Co, and Mo) and noble metal-based (Ru, Rh, Pt, and Pd) materials, and the supports are divided into the conventional oxides (Al2O3, SiO2, TiO2, ZrO2, and CeO2) and the supports with novel structures (e.g., metal-organic frameworks and carbon-based materials), which are all discussed and evaluated in depth. The preparation methods of catalyst are classified as the conventional ones (such as impregnation, coprecipitation, hydrothermal, sol-gel, and solid-phase synthesis) and unconventional ones. The latter includes three technologies such as ultrasound, microwave, and plasma, which can speed up the synthesis and reaction process and facilitate the high dispersion of the active components on the supports. Subsequently, two reaction mechanisms in CO2 methanation (the formate and CO pathways) are discussed. The specific reaction pathway for CO2 methanation is related to the properties of the catalyst surface (e.g., hydroxyl abundance, adsorbed O2- sites) and the reaction conditions (e.g., reaction temperature and pressure). Finally, current research challenges are put forward, and the prospects for future research in this area are made. Related Articles | Metrics

Select

Review of additives for electrolyte of sodium-ion battery Yuyue GUO Xiaoying ZHAI Ningbo ZHANG The Chinese Journal of Process Engineering    2023, 23 (8): 1089-1101.   DOI: 10.12034/j.issn.1009-606X.223104 Abstract （1389）   HTML （75）    PDF （3494KB）（1399）       Knowledge map    Save With the upsurge of the energy revolution, secondary battery as a new way of energy storage has been widely concerned owing to their efficient energy conversion. As we all know, lithium-ion batteries (LIBs) have high operating voltage and high energy density, they can be used in various application scenarios, such as electrical vehicles (EV), portable electronic devices, and large-scale energy storage systems. However, due to the shortage of lithium resources and rising prices of raw materials, many battery companies are observed to undergo cost pressure and bankruptcy risk. Given this, sodium-ion batteries (SIBs) work similarly to lithium-ion batteries, but they have great advantages in terms of resource reserve, low cost, low temperature, rate performance, and safety, thus have received strong attention from researchers and engineers. In the sodium-ion battery system, it is also composed of the positive electrode, negative electrode, electrolyte, separator, and other key components. The electrolyte, as the intermediate bridge connecting the positive and negative electrode material system, plays a vital role to undertake the transport of sodium ions, which mainly consists of organic solvent, sodium salt, and additives. The introduction of a small number of functional additives can significantly improve the overall performance of the battery because it constructs a solid electrolyte interface (SEI) between electrolyte and electrode. Different kinds of additives can exhibit specific properties to meet different conditions. This review focuses on the use of electrolyte additives, including unsaturated carbonates, sulfur compounds, phosphorus compounds, silicon compounds, inorganic sodium salts, and other types of components. Meanwhile, the research progress and related mechanisms of this addition agent in the electrolyte of sodium-ion batteries in recent years were summarized as a reference for subsequent research. Finally, the future study of electrolyte additives prospects from the science idea and practical application, for example, density functional theory, AI for science, and in-situ analysis method for SIBs. Related Articles | Metrics

Select

Progress on catalysts for hydrogen production by low temperature methanol water reforming Zhan SHEN Zhidong JIANG Pengfei ZHANG Ziyu ZHANG Haiying CHE Zifeng MA The Chinese Journal of Process Engineering    2022, 22 (5): 573-585.   DOI: 10.12034/j.issn.1009-606X.221147 Abstract （1119）      PDF （1690KB）（390）       Knowledge map    Save Methanol is a promising energy carrier owing to its simple structure, high hydrogen content and huge production capacity. Methanol steam reforming (MSR) is an energy-saving and efficient on-site hydrogen production method. Combined with fuel cells, MSR can be applied in many fields. However, due to the high reaction temperature (250~300℃), there are some problems such as slow start-up, high CO content and low thermal efficiency. Low temperature methanol water reforming (LT-MWR), including LT-MSR and aqueous-phase reforming of methanol (APRM), means that the reaction proceeds below 200℃, and maintains high reaction activity, which can reduce the preheating time and the side reactions, and achieve stronger thermal coupling with fuel cells. In this review, the performance and defects of commercial catalysts are firstly introduced based on characterization results. The research of LT-MWR catalysts for hydrogen production is reviewed, including Cu-based catalysts, noble metal catalysts and photo-synergistic catalysts. The modification strategies for low temperature Cu-based catalysts are summarized, including synthesis methods, structure design and element doping. The commercial CuZnAlOx catalyst at home and abroad has the characteristics of high methanol conversion and good stability, despite its relatively high price and low activity below 200℃. Because the activity of Cu-based catalysts is greatly affected by temperature, the catalytic activity decreases sharply at low temperature. By appropriate modification, Cu-based catalysts can perform high activity at low temperature. Noble metal catalysts have high activity at low temperature, but they are expensive and the synthesis process is complex. Photo-synergistic catalysts are functional under the condition of light, which is still in the research stage. The synthesis method can strengthen the micromixing degree and reproducibility. Appropriate structure design can increase the specific surface area and thermal stability of the catalyst. Element doping enables better dispersion of active components and modifies the surface structure. Three modification strategies can effectively improve the performance of Cu-based catalyst for LT-MSR, reducing the content of CO content while maintaining high activity. Finally, the prospect and challenges of LT-MSR catalysts for hydrogen production are prospected. Related Articles | Metrics

Select

Research progress of thermal management technology for lithium-ion batteries Jiaxin LI Pengzhao LI Miao WANG Chun CHEN Liangyu YAN Yue GAO Shengchen YANG Manman CHEN Cai ZHAO Jing MAO The Chinese Journal of Process Engineering    2023, 23 (8): 1102-1117.   DOI: 10.12034/j.issn.1009-606X.223094 Abstract （1017）   HTML （44）    PDF （13593KB）（428）       Knowledge map    Save Efficient battery thermal management technology is critical to the safe operation, long cycle life, and overall cost reduction of lithium-ion batteries and is important in promoting the large-scale application of lithium-ion batteries. In this review, several mainstream battery thermal management technologies are discussed in detail, including air cooling, liquid cooling, new phase change material cooling, and thermoelectric cooling technology. The battery heat generation model is briefly described. Finally, the development direction of battery cooling technology is prospected. Air cooling technology is simple in structure, but it is difficult to ensure temperature uniformity of the cells within the battery pack and is not suitable for cooling large lithium-ion battery packs, but is more suitable for small flying electric devices and low-end electric vehicles. Cooling plate liquid cooling technology is more effective, but there is a risk of coolant leakage and the temperature uniformity needs to be further improved. Immersion liquid cooling technology offers significant cooling and temperature uniformity but is expensive and is likely to be used more often in the future in energy storage plants with high cooling requirements, while for most lithium-ion electric vehicles the lower-cost cooling plate liquid cooling technology is more suitable. Phase change material cooling and thermoelectric cooling technologies without moving parts have achieved initial commercial application in electronic equipment and small power plants, but the cooling efficiency is low and needs further refinement. It is worth noting that it is critical to choose the right cooling technology for the user's needs. While there is no perfect cooling solution, a combination of cooling technologies can be used to meet the thermal management needs of a wider range of application scenarios. Related Articles | Metrics

Select

Current application and development of microneedle Sibo ZHAO Yiru BAO Min XIE The Chinese Journal of Process Engineering    2023, 23 (2): 163-172.   DOI: 10.12034/j.issn.1009-606X.222114 Abstract （953）   HTML （179）    PDF （2905KB）（396）       Knowledge map    Save Microneedles are micrometer sized single needles or needle arrays that are produced by microfabricating techniques. Microneedles could penetrate the stratum corneum layer of the skin to reach the dermal layer which is favorable for percutaneous drug delivery. Microneedles have a number of advantages in drug delivery, compared with oral administration, microneedles circumvent the metabolic effects of the digestive system on drugs, compared with injection needles, microneedles are able to reduce pain and improve adherence compliance in patients. Due to their special transdermal pathway and precise, convenient application methods, microneedle has also become a hot studies area in biomedicine at present and their applications in vaccination, tissue fluid extraction and biomarker detection, etc. have been well investigated. According to working mechanisms for percutaneous drug delivery, microneedles can be classified as five kinds, including solid, coated, dissolving, hollow, and hydrogel microneedles. This review, combined with relevant articles in the field of microneedle technology in recent years, provides a brief overview of the types and fabricating materials of microneedles, mainly introduces the current applications of microneedles in the field of drug delivery (such as insulin injection for diabetes treatment, local drug delivery for cancer treatment, vaccination, tissue fluid extraction and biomarker detection, etc.) Besides, if the microneedles would be widely applied in the marker for medical application, some factors including mechanic strength, biological safety, sterilization process and biological stability of biomolecules on the micrneedles should be well considered which are also discussed in the review. At last, outlooks on microneedles' future development are prospected, such as developing microneedles based drug delivery system for heart attack treatment, improving biological stability of the biological molecules on the microneedles for convenient vaccination, and combining of microneedles with other techniques, such as sensitive biomarker detection method, microfluidic chip and wearable device, which will open a new prospect for the development of microneedles techniques. Related Articles | Metrics

Select

Research progress of bubble separation behavior on electrodes and its strengthening technology Wei LIN Zhangwei WANG Wei WANG Jimin LI Zixin GUO Jin XIANG Xinyuan QIU Hongyang ZHAN Jiuyang YU The Chinese Journal of Process Engineering    2022, 22 (9): 1147-1158.   DOI: 10.12034/j.issn.1009-606X.221283 Abstract （839）   HTML （34）    PDF （3257KB）（400）       Knowledge map    Save The rapid development of the global economy inevitably caused the rapid consumption of fossil resources and serious environmental pollution problems. Hydrogen plays an increasingly important role in energy supply and environmental protection as a clean energy, water electrolysis is a way to produce hydrogen on a large scale, so it is very important to enhance the efficiency of water electrolysis for hydrogen energy production. How to improve the electrolysis efficiency of water electrolysis technology has been widely concerned. During electrolysis, the gas produced at both ends of the electrode can go in one of three directions: out of the cell, dissolved in the electrolyte, or attached to the electrode. However, in the electrolysis process, the bubbles attached to the electrode will seriously affect the contact area between the electrode and electrolyte, which directly reduces the electrolysis efficiency. Therefore, reducing the residence time of bubbles on the electrode can effectively increase the contact time between electrolyte and electrode and improve the efficiency of hydrogen production. In this work, the recent progress in promoting the separation of hydrogen and oxygen bubbles from the plate during electrolysis is reviewed. The nucleation, growth, coalescence and separation of bubbles are studied from the aspects of plate properties, current, solution concentration, and external physical field, and the characteristics of various methods to enhance bubble separation are discussed and summarized. The electrolytic efficiency can be improved and the energy consumption of electrolysis can be reduced by promoting the bubble separation on the electrode. The future development direction and route are prospected, this provides fundamental insight and direction for the future design of the bubble separation technology in water electrolysis. Related Articles | Metrics

Select

Research progress on sodium storage mechanism and performance of anode materials for sodium-ion batteries Cheng HAN Shaojie WU Chaoyang WU Mingyang LI Hongming LONG Xiangpeng GAO The Chinese Journal of Process Engineering    2023, 23 (2): 173-187.   DOI: 10.12034/j.issn.1009-606X.222083 Abstract （809）   HTML （20）    PDF （1833KB）（314）       Knowledge map    Save The massive use of fossil fuels is bound to cause irreversible damage to the global ecological environment. New energy sources such as solar, wind, and tidal have the advantages of being clean, non-hazardous, and renewable, and can be used to replace fossil fuels to alleviate the environmental crisis. The development and utilization of green energy have led to the rapid development of electrochemical energy storage and conversion technologies to store clean and renewable energy in the grid. Lithium-ion batteries, one of the most successful secondary ion batteries in energy storage, have been used in various electronic products, but expensive and scarce raw material resources limit their applications in the field of large-scale energy storage equipment. Therefore, the search for inexpensive secondary ion batteries with excellent performance is one of the hot research topics nowadays. As a new type of secondary ion battery, sodium-ion battery not only has a similar working principle as a lithium-ion battery but also features low cost, high resource abundance, and high reversible capacity. The extensive exploration by researchers is expected to make it a successful alternative to lithium-ion batteries for commercial production. This work mainly reviews the progress of the research on the performance of sodium-ion battery anode materials, firstly, the three mechanisms of sodium storage in the anode materials, namely the intercalation reaction, alloying reaction, and conversion reaction, are analyzed and summarized according to the different ways of sodium ion storage in the anode materials. Then, according to the performance of sodium-ion battery anode materials, three common modifications of anode materials are summarized: structural modification, elemental doping, and material compounding, and the electrochemical properties of anode materials before and after modification are compared. Then, the research status and problems faced by several key anode materials for sodium-ion batteries, such as carbon-based materials, titanium-based materials, alloy-based materials, conversion-based materials, and organic materials, are highlighted. Finally, the research directions of sodium-ion battery anode materials are prospected based on the actual production and industrial applications. Related Articles | Metrics

Select

Effects of hole distribution on flow field and noise for multi-hole plates Qian LI Hua JI Donglin FENG Ziyang ZHANG Zongxing DUAN The Chinese Journal of Process Engineering    2022, 22 (5): 601-611.   DOI: 10.12034/j.issn.1009-606X.221131 Abstract （785）      PDF （1788KB）（224）       Knowledge map    Save At present, the multi-hole plates with uniform hole distribution structure are widely used in the process industry to limit the flow and reduce the pressure, vibration and noise because of low manufacturing cost, simple structure, easy processing, easy installation and maintenance. In order to further improve the flow stability and reduce the flow noise, multi-hole plates of non-uniform hole distribution with different hole spacing, hole number, and hole diameter are designed with the equivalent opening diameter unchanged. Based on the numerical results, the velocity, pressure, reflux characteristics, jet convergence and flow development in the pipeline with different multi-hole plates are compared in detail to analyze the flow field characteristics. Moreover, the noise of multi-hole plates is numerically calculated by the acoustic analogy model. The observation points are set on the centerline and the section perpendicular to the flow direction to compare the spectrum characteristics and the overall sound pressure level. The numerical results show that the decrease of hole spacing with equal difference, the increase of hole number on the plate edge, and the increase of hole diameter without reducing the hole number can all effectively improve the flow stability and reduce the noise level of multi-hole plates without influencing the pressure drop ability compared with the general multi-hole plate with uniform hole distribution, and the maximum decrease of noise level is 5.62, 6.10 and 7.00 dB respectively. Related Articles | Metrics

Select

Research progress in modification of layered oxide cathode materials for sodium-ion batteries Miaomiao LI Xiangyun QIU Yanxin YIN Tao ZHANG Zuoqiang DAI The Chinese Journal of Process Engineering    2023, 23 (6): 799-813.   DOI: 10.12034/j.issn.1009-606X.222296 Abstract （776）   HTML （110）    PDF （47402KB）（553）       Knowledge map    Save Sodium-ion batteries (SIBs) have been regarded as the major candidate technologies for large-scale energy storage applications due to the rich abundance of Na sources, low cost and safety. And the development of cathode materials also determines the final performances and commercialization. Layered oxide cathode materials have the advantages of high specific capacity, simple structure and good stability. It is one of the most promising sodium cathode materials at present. However, such materials are still faced with irreversible changes in the electrochemical process, unstable storage in air and poor interface stability, which seriously restricts the development of commercialization of SIBs. In order to solve these problems of materials, researchers modified and optimized them. Accordingly, the modification measures of ion doping, surface coating, nanostructure design and P/O mixing and other related modification measures of sodium electric layered oxide cathode materials, which provides a basis for the modification research of sodium electric layered oxide cathode materials are reviewed in this review. Besides, the future development trend of layered oxides is prospected. Related Articles | Metrics

Select

Heat integrated double solvent extractive distillation process of tetrahydrofuran-methanol-methyl acetate-water Chao LOU Ming LI Yi YUN Dehao WAN Deming YANG The Chinese Journal of Process Engineering    2022, 22 (7): 882-890.   DOI: 10.12034/j.issn.1009-606X.221316 Abstract （768）   HTML （45）    PDF （1335KB）（203）       Knowledge map    Save According to the characteristics of multiple binary azeotropes in the tetrahydrofuran-methanol-methyl acetate-water quaternary system, two distillation processes, conventional double solvent extractive distillation, and heat integrated double solvent extractive distillation were proposed. The solvent was selected based on the thermodynamic data calculated by the WILSON equation. The results showed that water was the most suitable solvent for tetrahydrofuran-methanol and methyl acetate-methanol azeotropes, and ethylene glycol was the most suitable solvent for tetrahydrofuran-water and methyl acetate-water azeotropes, the total solvent ratio was 0.65 and the ratio of ethylene glycol to water was 1.3. On this basis, taking energy consumption and total annual cost (TAC) as the evaluation indexes of the distillation process, the proposed conventional double solvent extractive distillation and heat integrated double solvent extractive distillation were simulated. The heat exchange network of the double solvent extractive distillation system was optimized by pinch analysis technology. The results showed that the cold utility consumption of the optimized heat exchange network was reduced by 44.12%, and the heat utility consumption was saved by 42.49%. Compared with the conventional double solvent extractive distillation process, the energy consumption of heat integrated double solvent extractive distillation process was reduced by about 43.29%, TAC was saved by approximately 26.89%, and the thermodynamic efficiency was increased by 3.25%. It can be seen that the heat-integrated double solvent extractive distillation process has better technical and economic advantages for separating the above quaternary system. Related Articles | Metrics

Select

Study on oxyfuel combustion behavior and the intrinsic kinetics of typically sized coal particles Haolong BAI Liangliang FU Guangwen XU Dingrong BAI The Chinese Journal of Process Engineering    2022, 22 (8): 1115-1123.   DOI: 10.12034/j.issn.1009-606X.221256 Abstract （763）   HTML （5）    PDF （1151KB）（72）       Knowledge map    Save Oxyfuel combustion is a promising technology to facilitate carbon capture from combustion-generated flue gases. Circulating fluidized beds (CFBs), the major commercial-scale boilers, will play a significant role in the energy industry's transition from today's carbon-intensive to carbon neutral in the future. The types of boilers combust coals of wide screening particle sizes of 0~10 mm. The difference in coal particle size inevitably leads to a considerable variation in combustion characteristics, which has not yet been fully understood. In particular, little is known about the dynamic evolution behavior of combustion gas products and the intrinsic kinetics of the in-situ produced nascent char particles when these typically sized coal particles are combusted in fluidized beds. For this reason, an advanced micro fluidized bed reaction analyzer (MFBRA), integrated with a fast-responding process mass spectrometry, was employed to investigate the oxyfuel combustion behavior of two typically sized coal particles (i.e., 1.7~3.35 mm and 0.12~0.23 mm), typical of those in dense region and dilute region in CFBs, at 790~900℃. The use of MFBRA enabled the successful detection and characterization of the dynamic combustion process-sequentially occurring devolatilization and combustions of the in-situ produced volatiles and the nascent char particles. The results demonstrated that the combustions of volatiles and nascent char particles can have similar or different rates depending on the coal particle size. The two major successively occurring dynamic processes were distinctively identified and characterized for the coarse particles but not for the fine particles, which were featured with similar reaction rates for the two processes. The combustion of coarse char particles was rate-controlled by kinetics at low temperatures and changed to interparticle diffusion control at high temperatures. The combustion kinetics of the volatiles and nascent char were analyzed, and the corresponding values of activation energy were 107.2 and 143.9 kJ/mol, respectively. Related Articles | Metrics

Select

Advances in biosynthesis of diamine as core monomers of new nylon materials Kun LIN Zhuang LI Kun WANG Ying BI Xiuling JI Zhigang ZHANG Yuhong HUANG The Chinese Journal of Process Engineering    2023, 23 (7): 958-971.   DOI: 10.12034/j.issn.1009-606X.223147 Abstract （761）   HTML （25）    PDF （1140KB）（598）       Knowledge map    Save In the context of carbon neutrality, bio-diamine synthesis is an effective way to achieve the low-carbon production and sustainable development. Using synthetic biology, metabolic engineering, protein engineering strategies, we are able to design and construct efficient key enzymes and pathways for the biosynthesis of diamines. In this work, the progress of diamine synthesis is reviewed around two synthetic strategies: microbial de novo fermentation and whole-cell catalysis. The main diamines include 1,4-butanediamine, 1,5-pentanediamine, and 1,6-hexamethylenediamine. The biosynthesis of butanediamine mainly includes ornithine decarboxylation and lysine decarboxylation pathways, and butanediamine is mainly produced by fermentation. However, the current yield of butanediamine is low and cannot meet the requirments of industrial production. The biosynthesis of pentanediamine depends on the decarbosylation of L-lysine, mainly by de novo fermentation and whole-cell catalysis. The whole-cell catalysis for pentanediamine is more efficient, which has been widely used in large-scale production with the maturity of the technology. Hexamethylenediamine is currently synthesized by constructing artificial pathways. In addition, to address the challenges encountered in the biosynthesis of diamines, such as many by-products, poor strain activity, low yield, difficult separation, and purification, we proposed methods to improve the biosynthesis of diamines by combining metabolic engineering and protein engineering to optimize key enzyme catalysis, exploring the mechanism of cell damage caused by diamine accumulation, enhancing the specificity and activity of enzyme catalysis to improve production intensity, and optimizing the fermentation system to simplify the subsequent separation and purification steps. Finally, we foresee the future direction and development prospect of diamine biosynthesis. Related Articles | Metrics

Select

Research progress of adsorption method to remove tetracycline from wastewater Xiong LAN Qin LIU Xintao ZHOU Zhongqiu LUO Xiaoteng ZHAO Yan LU The Chinese Journal of Process Engineering    2022, 22 (8): 989-1000.   DOI: 10.12034/j.issn.1009-606X.221261 Abstract （731）   HTML （24）    PDF （6695KB）（244）       Knowledge map    Save Tetracycline (TC) is a broad-spectrum antibiotic with large production and application at present. Its chemical properties are relatively stable and difficult to metabolize, so it is easy to accumulate in soil and water. The abuse of antibiotics not only increases the drug resistance of bacteria, but also produces resistance genes and induces the production of super-bacteria. Therefore, the harmless treatment of wastewater containing TC is urgent. Adsorption method has the advantages of easy operation, high removal rate, economy, and environmental protection. It is widely considered as an efficient method to remove antibiotics. The adsorption materials used to remove tetracycline from wastewater are different and various. This work mainly summarizes three kinds of common adsorbents: carbon materials, metal organic framework materials, and mineral materials. The adsorption capacity of the above materials for TC is listed, and the effects of pH value, temperature, ionic strength and other factors on the adsorption process of TC are analyzed. On this basis, the fitting of different adsorption kinetics and thermodynamic models when these three kinds of materials adsorb TC is analyzed. It is found that the adsorption kinetics of most materials meets with the quasi-second-order kinetic model, and the adsorption thermodynamics of the Freundlich thermodynamic model are better to describe the adsorption process. In addition, the mechanism involved in the removal of TC is also described. Finally, the advantages and disadvantages of these three kinds of materials in the study of TC adsorption are compared, and the future research focus is prospected, which provides a reference for accelerating the preparation of more economical, efficient and renewable TC removal adsorption materials. Related Articles | Metrics

Select

Research review in regulating interfacial interaction on MOF-based mixed matrix membranes for gas separation Lili GONG Ju BAI Can WANG Wei LAI Linglong SHAN Shuangjiang LUO Zhichang LIU The Chinese Journal of Process Engineering    2023, 23 (4): 489-500.   DOI: 10.12034/j.issn.1009-606X.223054 Abstract （678）   HTML （31）    PDF （7406KB）（619）       Knowledge map    Save Mixed matrix membranes (MMMs) have attracted substantial attention for gas separation, combining the advantages of organic polymers and inorganic fillers, which are expected to solve the Trade-off effect. Metal organic frameworks (MOF), as a kind of innovative filler, provided promising development opportunities for MMMs, thanks to high surface area and porosity, adjustable pores, and low density, etc. These unique physical and chemical properties promoted the application in gas adsorption, separation, and storage. MOF is regarded as good compatibility with the polymer matrix because the organic linkers in MOF are more similar to the organic chain of the polymer compared with traditional inorganic materials (molecular sieve or metal oxide, etc.). Gas separation performance is improved by incorporating MOF into the polymer matrix, which is expected to balance the Trade-off effect. However, the separation performance of MMMs is not simply the sum of the two phases and is far below the predicted theoretical value by the material simulation in most cases. One of the key reasons for these non-ideal morphologies resulting from poor interfacial compatibility, including the non-selective interfacial voids, polymer rigidified, and pore blockage, which reduce the separation performance of MMMs. Therefore, good interfacial compatibility plays a key role in MMMs. Constructing effective interface interactions is a feasible strategy to improve interface compatibility. Thus, in this review, a comprehensive overview of the main technical challenges in developing MOF-based MMMs and a detailed description of the interface issues are provided. And constructing different interface interactions, including hydrogen bonds, covalent bonds, coordination bonds and others, has been expounded through various methods and strategies in the last five years. Finally, it aims to summarize the positive effects on the properties of MMMs through effective and strong interface interactions, guiding the future development of MOF-based MMMs. Related Articles | Metrics

Select

Research progress on molding process of catalysts for fixed bed reactor Shanshan LIU Qida DING Tao GUO Yaofeng WANG Baohua XU The Chinese Journal of Process Engineering    2023, 23 (4): 501-511.   DOI: 10.12034/j.issn.1009-606X.222088 Abstract （629）   HTML （24）    PDF （1464KB）（366）       Knowledge map    Save The progresses obtained in the catalytic technology are driven by the social demands, such as environment, energy, chemicals, and fuels. The ultimate goal is to increase the process efficiency for scale-up. The molding catalysts are usually multicomponent material of millimetre-size consisting of the active phases, supports, and various molding additives suitable for commercial applications. Different from the powder catalysts, the molding catalysts should not only possess the catalytic activity of the powder catalyst but also consider the use of binder, lubricant, acid and pore-forming agent to satisfy the required mechanical strength and chemical stability to ensure that they can run smoothly and have a long life in industrial reactors. In addition, the shape and size of the molding catalysts affect the catalytic performance by affecting the flow state of the materials inside the reactor. Therefore, the molding process is complex and full of challenges. This review introduces the influence of molding conditions on both the mechanical and the catalytic properties at the fixed bed. Specifically, the effects of the types and amounts of additives, the addition sequence, the calcination conditions, the pulp ratio, and the shape and size of molding catalysts are focused. Weibull modulus can be used to measure the reliability of mechanical strength of brittle materials, and further judge and predict the reliability of catalyst strength value. In addition, this review also introduces the application of Weibull distribution in the reliability judgment and prediction of catalyst strength value, and the progress of computational fluid dynamics (CFD) simulation in assisting catalyst morphology design. The potential of Weibull distribution and CFD in future applications of molding catalyst are pointed out. Related Articles | Metrics

Select

Research progress of fluidized bed direct reduction at Institute of Process Engineering Chuanlin FAN Zhan DU Feng PAN Zheng ZOU Jun LI Hongzhong LI Qingshan ZHU The Chinese Journal of Process Engineering    2022, 22 (10): 1325-1332.   DOI: 10.12034/j.issn.1009-606X.222325 Abstract （624）   HTML （36）    PDF （4964KB）（368）       Knowledge map    Save Under the background of carbon peaking and carbon neutrality, iron and steel industry urgently needs low-carbon reconstruction. Hydrogen direct reduction (usually called "hydrogen metallurgy") is an important research field in the domestic and overseas. Fluidized bed (FB) direct reduction has been the research direction at Institute of Process Engineering (IPE) for more than 60 years. On the occasion of commemorating the 120th anniversary of Professor Chu-Phay Yap's birth, this work reviews and summarizes a series of important achievements on basic researches and industrial applications of FB direct reduction at IPE. In the basic researches respect, the competition of adhesive force and rupturing force for particle sticking, the behaviors of agglomerate fluidization and slow defluidization, the growth mechanisms and sticking characteristics of newly formed iron with different morphologies were revealed; and a series of methods for anti-defluidization were successively established, including particle coating and iron morphology regulation to reduce the adhesive force, and enhance particle motion, particle size increase, using external field forces to increase the rupturing force. Furthermore, several pilot plants with various iron ores were constructed and operated to promote the industrial application of new technologies, including hydrogen FB direct reduction of 100 kg/d iron ore concentrate, 1 t/d vanadium bearing titanomagnetite and FB direct reduction-electric furnace smelting of 2000 t/a vanadium bearing titanomagnetite. Currently, IPE is cooperating with Ansteel Group to establish the world's first FB direct reduction pilot plant of 10 000 t-DRI/a using green hydrogen. This paper aims to commemorates Professor Chu-Phay Yap, Professor Mooson Kwauk and other scientists of the older generation, and also to propel advance of basic theory and technology in FB direct reduction, for promotion of the low-carbon development for the iron and steel industry of China. Related Articles | Metrics

Select

A novel process for preparation Ti-rich material from modified electric furnace titanium slag by phase deconstruction method Yusheng ZHOU Guanzhou QIU Jianfa JING Fuqiang ZHENG Shuai WANG Feng CHEN Yufeng GUO The Chinese Journal of Process Engineering    2022, 22 (5): 651-659.   DOI: 10.12034/j.issn.1009-606X.221137 Abstract （617）      PDF （1869KB）（235）       Knowledge map    Save In this study, a novel process for preparation rich-titanium material from modified titanium slag after melting in electric furnace by ammonium hydrogen fluoride leaching and hydrochloric acid leaching was proposed. The thermodynamic analysis of ammonium hydrogen fluoride leaching and hydrochloric acid leaching were investigated. The thermodynamic results of ammonium hydrogen fluoride leaching indicated that a small part of anosovite and the silicate can be decomposed, the silicate react with ammonium hydrogen fluoride leaching to produce sediment (CaMg2Al2F12), CaF2 and AlF3. The element of Si was converted to (NH4)2SiF6 existed in solution. The effects of ammonium hydrogen fluoride leaching conditions on the impurities extraction rate were investigated. The results indicated that the extraction rate of Si, Al, Ti, Fe, Ca and Mg were 93.55wt%, 28.03wt%, 3.88wt%, 20.50wt%, 3.40wt% and 2.45wt% respectively when the concentration of ammonium hydrogen fluoride was 15wt%, the liquid-solid ratio was 10:1, the temperature was 20℃ and the time was 2 h. The XRD results showed that the main phases in residue were rutile, anosovite and sediment (CaMg2Al2F12), the diopside was decomposed by ammonium hydrogen fluoride leaching. The thermodynamic results of hydrochloric acid leaching indicated that the sediment (CaMg2Al2F12), CaF2, AlF3 and the residual anovosite was decomposed by hydrochloric acid leaching. The effects of hydrochloric acid leaching conditions on the impurities extraction rate were investigated. The results of hydrochloric acid leaching indicated that the extraction rate of Ca, Al, Mg, Ti, Si and Fe were 86.78wt%, 62.33wt%, 92.31wt%, 18.08wt%, 40.23wt% and 75.36wt% respectively when the concentration of hydrochloric acid was 20wt%, the liquid-solid ratio was 8:1, the temperature was 120℃ and the time was 2 h. The main phase after hydrochloric acid leaching was rutile. The XRD results indicated that the sediment (CaMg2Al2F12) phase was solute by hydrochloric acid leaching. The titanium dioxide grade in rich-titanium material was 95.20wt%, the content of CaO was 0.49wt%, and the content of MgO was 0.48wt% which meet the need of boiling chlorination charge. Related Articles | Metrics

Select

Research progress and application of heat transfer enhancement of twisted oval tubes Xiuzhen LI Yingying TAN Junfei YUAN Zhanwei WANG Lin WANG The Chinese Journal of Process Engineering    2022, 22 (5): 561-572.   DOI: 10.12034/j.issn.1009-606X.221153 Abstract （599）      PDF （6683KB）（346）       Knowledge map    Save The twisted oval tube has simple structure, excellent heat transfer enhancement and anti-fouling performance, and has become one of the research hotspots in the field of passive heat transfer enhancement. In recent years, researchers have carried out a lot of research on the heat transfer performance of twisted elliptical tubes (bundles) through experiments and numerical simulations. The mechanism of heat transfer enhancement is explained.Although there are reviews on the technology of twisted oval tube exchangers, there are deficiencies in the induction of the heat transfer enhancement characteristics of twisted oval tubes and the analysis of the research clues of the engineering application. This review focuses on the internal and external heat transfer and flow resistance performance of the twisted oval tube, and summarizes the influence of the structure of the twisted oval tube (bundle), working fluid and flow state on the heat transfer performance and flow resistance characteristics. The review also reviews the engineering application cases of twisted oval tube heat exchangers, and outlines the contents to be perfected in the researches on twisted oval tubes, and prospects the development trend of the research on heat transfer intensification of twisted oval tubes. This review is expected to provide guidance and reference for deepening the theoretical research and engineering practice of twisted oval tubes. Related Articles | Metrics

Select

Rigorous modelling and energy performance evaluation for PDH reaction gas separation and hydrogen purification Xuantong LU Jin ZHAO Chun DENG The Chinese Journal of Process Engineering    2023, 23 (1): 144-153.   DOI: 10.12034/j.issn.1009-606X.221334 Abstract （586）   HTML （2）    PDF （1123KB）（178）       Knowledge map    Save Propane dehydrogenation is one of the main processes for propylene production and its reaction gas components are complex, containing products from main reactions and by-product components such as CO2 and CO from side reactions. To obtain polymer grade propylene and purified hydrogen product with a purity of more than 99.90 mol/mol, the separation process of the reaction gas of propane dehydrogenation and the recovery of hydrogen from hydrogen-rich tail gas is modeled and simulated in the Aspen software. The process includes main modules such as MEA decarburization, compressed cryogenic separation, deethanization, propylene distillation and pressure swing adsorption. The CO2 contained in the reaction gas would affect the purity of the propylene product, and it is difficult to remove in the cryogenic process. Thus the CO2 is first removed by the MEA solvent absorption. The reaction gas after decarburization and dehydration enters the deethanizer and the propylene distillation unit, and the hydrogen-rich tail gas enters the pressure swing adsorption unit for further purification. In order to reasonably utilize the energy of the propylene distillation tower, the heat pump distillation process is adopted for the energy integration. Compared with conventional distillation, the energy consumption of propylene heat pump distillation is lower. Sensitivity analysis and optimization of process parameters for hydrogen recovery by pressure swing adsorption are carried out to improve economy and energy efficiency. For the two-bed four-step pressure swing adsorption process, the effects of adsorption pressure, adsorption time and purge ratio on the purity and recovery of hydrogen products are analyzed, and the optimal operating conditions are determined. The simulation results show propylene and hydrogen products meet the requirements. The energy consumption per unit product is 267.46 kg standard oil/t propylene product and 474.44 kg standard oil/t hydrogen product. It has a certain reference significance for the simulation of the actual propane dehydrogenation reaction gas separation process and energy consumption estimation. Related Articles | Metrics

Select

Research on the properties of LiNi0.8Co0.1Mn0.1O2 high nickel ternary cathode material for lithium ion batteries Cheng CAI Haiyan ZHANG Ying WANG Haikuo FU Ling HUANG Renheng TANG Fangming XIAO The Chinese Journal of Process Engineering    2022, 22 (6): 754-763.   DOI: 10.12034/j.issn.1009-606X.221194 Abstract （580）   HTML （24）    PDF （3206KB）（145）       Knowledge map    Save The Ni-rich cathode material (LiNi0.8Co0.1Mn0.1O2) has the advantage of high capacity and is the most potential cathode material for lithium-ion batteries. However, the poor cycle performance and rate capability limit its application. In this work, the structure evolution of the cathode material during the synthesis process and the influence of manufacturing temperature on the material properties were studied, and the potential causes of the structural changes and electrochemical degradation of the cathode material during the cycle were analyzed in detail. The physicochemical characterizations were conducted by employing the thermal gravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), etc. The cycle performance, rate performance, and other electrochemical properties were examined by electrochemical testing equipment. The results showed that the cathode material synthesized at 500℃ for 4 h and 750℃ for 14 h presents uniform particle size, good spherical structure, smooth surface of primary particles, compact arrangement, and stable crystal structure, which can alleviate polarization during cycling. Due to the proper particle size obtained at the optimized synthesis temperature, a relatively high initial discharge capacity, small volume changes, and slowly increased interfacial film resistance for the material were achieved, contributing to good Li+ diffusion kinetics. At 0.2 C, the first discharge-specific capacity was 186.2 mAh/g and the first charge-discharge efficiency was 82.5%. At 1 C, the discharge-specific capacity before and after 100 cycles were 185.1 and 175.2 mAh/g, respectively, and the capacity retention rate was up to 95.2%. The study of the synthesis and structural changes of Ni-rich cathode materials in this work can deepen the understanding of the materials and help improve the electrochemical performance of the materials. Related Articles | Metrics

Select

Research progress on degradation of organic pollutants in water by catalytic ozonation Shuhuan WANG Lilong ZHOU Zhengjie LI Jilong HAN Runjing LIU Jimmy YUN The Chinese Journal of Process Engineering    2022, 22 (5): 586-600.   DOI: 10.12034/j.issn.1009-606X.221094 Abstract （550）      PDF （7082KB）（146）       Knowledge map    Save For the further development of industry and improvement of living resources for everyone, the pollution of water resources is one of the urgent problems to be solved nowadays. The organic pollutants can be removed effectively by the catalytic ozonation process and the method is easy to operate, so it has been used in industry widely. The selection of catalysts has an important influence on the catalytic oxidation process of organic pollutants. In this study, the mechanism of the homogeneous catalytic ozonation process and heterogeneous catalytic ozonation process were analyzed and summarized. The catalytic effects of noble metal catalysts, transition metal catalysts, alkaline earth metal catalysts, and non-metal catalysts that have been used in heterogeneous catalytic ozonation to remove organic pollutants were summarized. The methods that have been used to improve the catalytic activity of these catalysts were also reviewed. The effects of pH value, ozone concentration, catalyst dosage, and the concentration of organic matters on the process of catalytic ozonation were summarized. It is pointed out that the main problem in the process of degradation of organic pollutants by catalytic ozonation is the loss of active components and the reduction of catalytic activity in an aqueous solution. Therefore, for future research, the development and preparation of novel catalysts with high catalytic activity and stability remain the research focus of this process.We can take the measures of improving the adsorption capacity of the catalyst, improving the transfer capacity of ozone in water, and using the synergistic coupling of different active components to effectively inhibit the loss of active components, improve the service life of the catalyst and improve the stability of the catalyst at the same time, to achieve the purpose of effective degradation of organic pollutants. Related Articles | Metrics

Select

Technical consideration on the transition from "ultra-low emissions" to "reduction of pollution and carbon emissions" in China's iron and steel industry Tingyu ZHU Xiaolong LIU The Chinese Journal of Process Engineering    2022, 22 (10): 1360-1367.   DOI: 10.12034/j.issn.1009-606X.222353 Abstract （548）   HTML （22）    PDF （2835KB）（216）       Knowledge map    Save The iron and steel industry plays an important role in China's national economy, and it is also the largest pollution-carbon emission in China. In April 2019, five ministries and commissions jointly issued the "Opinions on Promoting the Implementation of Ultra-low Emissions in the Iron and Steel Industry", leading to a beginning of ultra-low emissions for industrial flue gas, and the air pollution emissions of China's steel industry achieved a significant reduction. Since the "14th Five-Year Plan", under the background of carbon peaking and carbon neutrality, with the proposal of pollution and carbon reduction, the problem of carbon incremental effect caused by ultra-low emission technologies has gradually become prominent, which has brought new technological needs to the steel industry. This work expounds the technological progress of ultra-low emissions in China's steel industry, summarizes the development direction of pollution and carbon reduction in the steel industry, and puts forward suggestions for the green and low-carbon development of the steel industry in the future, providing a reference for promoting the high-quality green development of China's steel industry. Related Articles | Metrics

Select

Numerical investigation of gas-assisted sludge atomization and breakup based on VOF-DPM coupled model Haihong FAN Zhou LI Binbin LI Lin LI Shuo SHANG Jiayang WANG The Chinese Journal of Process Engineering    2022, 22 (12): 1633-1642.   DOI: 10.12034/j.issn.1009-606X.221412 Abstract （527）   HTML （4）    PDF （3831KB）（156）       Knowledge map    Save Sewage sludge is an unavoidable by-product in the process of sewage treatment. Due to its characteristics of high pollution and difficult to treat, the efficient and harmless treatment of sludge is still facing certain challenges. A new sludge treatment technology, spray drying technology with relatively simple process and high value-added utilization after sludge atomization has a great promotion effect on sludge treatment. The gas-assisted atomizer has a good atomization effect on high-viscosity fluids, and can ensure a better atomization quality at a faster atomization rate. In the study of sludge atomization, many scholars have carried out certain researches, but there is no numerical simulation study of sludge atomization, and numerical simulation can be low-cost, more intuitive study of sludge atomization breakup, has certain advantages. In order to realize the numerical simulation of sludge atomization and breakup, computational fluid dynamics software is used to explore the influence of gas-assisted sludge atomization characteristics and operating parameters (gas velocity, gas-liquid ratio, spray angle) on the effect of sludge atomization. The results show that the density and viscosity of sludge gradually decrease with the increase of moisture content. Gas velocity, gas-liquid ratio and spray angle are the three most important operating parameters that affect sludge atomization and breakup. During the atomization process, the high-speed airflow makes the sludge vibrate and unstable at the front end of the atomizer, resulting in the tearing of the sludge and the breaking of the droplets. The density of droplets in the center area is greater than that in the edge area and there are a few large particles agglomerated. For sludge with moisture content of 87% and a density of 1.065×103 kg/m3, the atomization effect is the best when the gas velocity is 180 m/s, the gas-liquid ratio is 126.3, and the spray angle is 55°. The average particle size of the droplets is about 0.193 mm, and the experimental results are in good agreement with the simulated particle size, and the maximum relative error is 5.80%. Related Articles | Metrics

Select

Development trend for co-production of steel and chemical in the context of carbon neutrality Chunyan SHI Guoshuai ZHANG Yi LI Suojiang ZHANG The Chinese Journal of Process Engineering    2022, 22 (10): 1317-1324.   DOI: 10.12034/j.issn.1009-606X.222361 Abstract （523）   HTML （31）    PDF （2057KB）（189）       Knowledge map    Save The by-produced gas, waste heat, and steel slag as well as the current situation on the co-production of steel and chemical in the iron and steel industry are analyzed. The developing trend of green and low-carbon technologies is discussed and the new mode from "carbon fixation by chemical" to "carbon substitution by hydrogen" in carbon-free steelmaking in the future is prospected. Suggestions and measures are put forward to the application of new technologies for steel and chemical co-production. It is expected to establish a new sustainable industrial ecosystem with the steel industry as the leader coupled with the chemical industry to support the realization of China's carbon peaking and carbon neutrality goal. Related Articles | Metrics

Select

Progress on resource utilization and second utilization of chloride removal products from Friedel's salt precipitation method Yun GU Peng CHU Dongdong GE Shouqiang HUANG Min JIANG Hongying LÜ Wenxin ZHANG Yangyang LÜ Yang LÜ Yaheng ZHANG The Chinese Journal of Process Engineering    2024, 24 (2): 151-161.   DOI: 10.12034/j.issn.1009-606X.223122 Abstract （513）   HTML （15）    PDF （1474KB）（322）       Knowledge map    Save The high concentration of Cl- in wastewater can seriously corrode industrial equipment, and also pollute the water environment. A series of technologies for removing Cl- from wastewater have been reported, such as membrane separation, concentration, evaporation crystallization, chemical precipitation, adsorption, ion exchange, electrolysis, oxidation, and solvent extraction. Among them, chemical precipitation has significant advantages in equipment investment and operability, Friedel's salt precipitation method of Cl- removal has been intensively studied because of the wide source and low price of raw materials, compared with other methods using silver, copper, or bismuth. After the Cl- removal, a large quantity of chemical sludge is produced, which mainly contains Friedel's salt (3CaO?Al2O3?CaCl2?10H2O), katoite [Ca3Al2(OH)12], and calcium hydroxide, etc. Due to the complex components and the tight binding of Cl- in the interlayer spacing of Friedel's salt, the resultant sludge is difficult to recycle. To promote the application of Friedel's salt precipitation method, it is very important to utilize its Cl- removal products, especially Friedel's salt, as a resource. Based on the introduction of the compositional and structural characteristics of Friedel's salt, this work highlights the advantages of Friedel's salt precipitation method, which cannot only remove Cl-, but also obtain Friedel's salt, by comparing other preparation methods. According to the aluminum and calcium components of Friedel's salt and its layered bimetallic hydroxide structure, effective resource utilization can be carried out, including the removal of various heavy metal cations (i.e., Cu2+, Cd2+, Co2+, Zn2+, and Pb2+) and oxygenated anion complexes [i.e., Sb(OH)6-, AsO43-, SeO42-, and CrO42-], and the preparation of polyaluminum chloride coagulants and as sludge dewatering regulators, etc. These uses have broad application prospects, providing reference and exploration direction for the further development of Friedel's salt precipitation method. Related Articles | Metrics

Select

Research progress in the preparation of porous biomass carbon materials and their applications in supercapacitors Xuemin ZHANG Guanyu HE Shaoqi YIN Tingting HUANG Jinping LI Jian ZHENG The Chinese Journal of Process Engineering    2024, 24 (2): 127-138.   DOI: 10.12034/j.issn.1009-606X.223036 Abstract （505）   HTML （42）    PDF （1013KB）（404）       Knowledge map    Save The biomass carbon material is a kind of green and renewable energy material. Its efficient utilization is of great significance for the sustainable development of the energy environment and the green and low-carbon transition of energy. Biomass carbon materials are widely used in energy storage and conversion, catalysis, adsorption, and many other fields due to their porous nature, abundant functional groups, large specific surface area, excellent electrochemical performance, low cost, and renewable. However, the properties of biomass carbon materials are not only closely related to the microstructure, but also the heteroatom doping has an important impact on the structure and electrochemical properties of biomass carbon materials. The accurate structure regulation of biomass carbon materials is an effective way to improve their electrochemical performance. In this work, the preparation methods of biomass carbon materials and their applications in supercapacitors are comprehensively reviewed, and the relationship between the structure and properties of porous carbon materials is discussed. On this basis, the influence mechanism and rules of different conditions, and different preparation processes (such as material selection, material treatment, and activation mode) on the structure characteristics of biomass carbon materials are analyzed. In this review, the mechanism and rules of the influence of the structure characteristics on the electrochemical properties of porous biomass carbon materials are described in detail, and the preparation process and performance regulation of porous biomass carbon materials need to be perfected and improved. Finally, the main development directions of preparation technology and electrochemical properties of porous biomass carbon materials in the future are pointed out. Related Articles | Metrics

Select

Preparation of nano-calcium carbonate intensified by CO2 micro bubble and transfer-reaction analysis Liheng WANG Xiaoping GUAN Ning YANG Zuze MU The Chinese Journal of Process Engineering    2023, 23 (9): 1313-1324.   DOI: 10.12034/j.issn.1009-606X.222450 Abstract （500）   HTML （7）    PDF （2491KB）（330）       Knowledge map    Save Carbonization is one of the common methods to prepare nano calcium carbonate. Controlling the particle size and particle size distribution of calcium carbonate is the key to the preparation of high-quality nano-calcium carbonate by carbonization. Different operating conditions have different effects on the reaction products. The particle size and size distribution of calcium carbonate can be effectively controlled by controlling different reaction conditions to improve the mass transfer and reaction conditions in the slurry. In batch-operated bubble column reactor, gas flow rate and bubble size are factors affecting mass transfer. This study investigates the influences of operation condition (gas flow rate, initial slurry condition), bubble type (ordinary bubble, micro bubble) on carbonation reaction rate and particle size distribution of calcium carbonate. Furthermore, the effects of bubble type on the stable region and abrupt change region in carbonation reaction process are analyzed. The experimental results show that when using ordinary bubble, the increase of CO2 flow rate accelerates the reaction process and reduces the particle size of calcium carbonate, but it does not affect the time of abrupt change region. With increasing the slurry concentration, the particle size first decreases and then increases in small-diameter column with ordinary bubble. However, when using micro bubble, the particle size of calcium carbonate is significantly reduced, and the time of abrupt change region decreases with the increase of gas flow rate. Moreover, the CO2 flow rate is no longer an influential factor on calcium carbonate particle size, which means that the gas-liquid mass transfer process is not the rate controlling step of carbonation reaction. This study provides some references for studying the application of micro bubbles in calcium carbonate crystallization. Related Articles | Metrics

Select

Recycling of scrap lead paste to prepare lead powder by high efficiency electrolysis in choline chloride-ethylene glycol deep eutectic solvent Haoming HUANG Juanjian RU Yixin HUA Xiao GENG Wenwen ZHANG Mingqiang CHENG Daoxiang WANG The Chinese Journal of Process Engineering    2023, 23 (1): 107-114.   DOI: 10.12034/j.issn.1009-606X.221422 Abstract （494）   HTML （1）    PDF （2013KB）（155）       Knowledge map    Save As a clean energy source without pollution during use, lead-acid batteries have received close attention. However, lead-acid batteries contain a large amount of polluting heavy metals, and random disposal will pollute the environment and affect the ecological balance. In industry, the recovery of scrap lead paste (SLP) is usually treated by pyrotechnics, but it consumes a lot of energy and also produces pollutants such as sulfur dioxide and lead dust. In view of the existing problems, finding new recycling processes has become a research hotspot. Deep eutectic solvents (DESs) are a new generation of green solvents and have received more and more attention in recent years. Because of their good thermal stability and wide electrochemical window, DESs are widely used in the fields of metal extraction and material preparation. In this work, the recycling of scrap lead paste to prepare lead powders by electrolysis is discussed in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). Firstly, the phase composition of the scrap lead paste is analyzed by XRD, and the quantitative analysis of the scrap lead paste using Jade software shows that it mainly exists in the form of lead dioxide with a small amount of lead sulfate at the same time. And then, the electrochemical behavior of lead ion in 30 g/L SLP+ChCl-EG solution is investigated by cyclic voltammetry. The phase composition and microscopic morphology of the deposit product at different temperatures are examine using XRD and SEM techniques. The experimental results show that when scrap lead paste is added, Pb(IV) can be reduced preferential to Pb(II) due to the reducibility of ChCl-EG DES. Cyclic voltammetry indicates that the reduction of scrap lead paste to metal lead is a quasi-reversible process in ChCl-EG DES. The constant voltage deposition experiment show that when the temperature rises from 323 K to 363 K, the current efficiency rises from 67.26% to 96.06% and the specific energy consumption decreases from 961.57 kWh/t to 673.28 kWh/t. XRD and SEM results demonstrate that the deposit products obtained at different temperatures are pure metallic lead powders and their microscopic morphology are mainly rod-shaped and slight acicular. Related Articles | Metrics

Select

Green oxidation process for synthesis of 2-methyl-1,4-naphthoquinone from β-methylnaphthalene Jinwen PAN Suohe YANG Guangxiang HE Xiaoyan GUO Haibo JIN Lei MA The Chinese Journal of Process Engineering    2022, 22 (12): 1702-1709.   DOI: 10.12034/j.issn.1009-606X.221426 Abstract （489）   HTML （2）    PDF （1071KB）（76）       Knowledge map    Save 2-methyl-1,4-naphthoquinone (2-MNQ) is an important intermediate of K vitamins, which is widely used in medicine, pesticides, feed additives and other fields. However, this vitamin does not exist in nature, and artificial synthesis is the only way to produce 2-MNQ. In industry, vitamin K3 is prepared using 2-methylnaphthalene (2-MN) as raw material and chromic anhydride as an oxidant. This process produces a large amount of waste residue and wastewater containing chromium, causing irreversible pollution to the environment,and trace amounts of chromium in the product pose a threat to human health. Therefore, a new type of the green oxidation process was used for hydrogen peroxide oxidation. The process used 2-methylnaphthalene (2-MN) as raw material, (NH4)2S2O8 as initiator to prepare peroxygen with 30% H2O2 and glacial acetic acid under the catalysis of sulfuric acid. Acetic acid was added dropwise to the reaction solution to synthesize 2-methyl-1,4-naphthoquinone (2-MNQ) by oxidation, and its structure was characterized by ICIR, GC-MS, and LCMS, and the oxidation reaction mechanism and the type and content of by-products were verified. The main impurities were isomer 6-methyl-1,4-naphthoquinone and its by-products phthalic anhydride and 4-methylphthalic anhydride produced by excessive oxidation. The effects of catalyst, reaction temperature, reaction time, dosage of oxidizer and initiator on the yield and conversion of 2-MNQ were investigated. The conversion rate and yield of 2-MNQ were determined by HPLC (external standard method). The optimum reaction conditions were reaction temperature of 65℃, reaction time of 5 h, n(H2O2):n(2-MN)=26:1. The conversion rate of 2-methylnaphthalene was 99%, and the product yield was 34%. The innovation point of this work was to verify the reaction mechanism and the intermediate process in detail using the original external infrared, that was, the raw material 2-methylnaphthalene was oxidized by peracetic acid, the epoxidation reaction generated the intermediate, and then rearranged to generate 2-methylhydroxyquinone, and the oxidation continued to generate the target product 2-methyl-1,4-naphthalene quinone. The process has the characteristics of environment friendly, simple technology, mild operating conditions and easy availability of raw materials.The process uses 2-methylnaphthalene (2-MN) as raw material, (NH4)2S2O8 as initiator to prepare peroxygen with 30% H2O2 and glacial acetic acid under the catalysis of sulfuric acid. Acetic acid was added dropwise to the reaction solution to synthesize 2-methyl-1,4-naphthoquinone (2-MNQ) by oxidation, and its structure was characterized by ICIR, GC-MS, and LCMS, and the oxidation reaction mechanism and the type and content of by-products were verified. The main impurities were isomer 6-methyl-1,4-naphthoquinone and its by-products phthalic anhydride and 4-methylphthalic anhydride produced by excessive oxidation. The effects of catalyst, reaction temperature, reaction time, dosage of oxidizer and initiator on the yield and conversion of 2-MNQ were investigated. The conversion rate and yield of 2-MNQ were determined by HPLC (external standard method). The optimum reaction conditions were obtained reaction temperature 65℃, reaction time 5h, n(CH3COOOH):n(2-MN) = 26:1. The conversion rate of 2-methylnaphthalene was 98%, and the product yield was 35%. The innovation point of this paper is to verify the reaction mechanism and the intermediate process in detail using the original external infrared, that is, the raw material 2-methylnaphthalene is oxidized by oxyacetic acid, the epoxidation reaction generates the intermediate, and then the rearranges to generates 2-methylhydroxyquinone, and the oxidation continues to generate the target product 2-methyl-1, 4-naphthalene quinone. The process has the characteristics of environment friendly, simple technology, mild operating conditions and easy availability of raw materials. Related Articles | Metrics

Select

The influence mechanism of hydroxyl modification on the toluene adsorption by activated carbon based on molecular dynamics simulation Bang XIAO Qing CAO Peiyong MA Hailin BI Pengcheng LI The Chinese Journal of Process Engineering    2022, 22 (5): 660-670.   DOI: 10.12034/j.issn.1009-606X.221125 Abstract （489）      PDF （3688KB）（112）       Knowledge map    Save In this work, activated carbon models modified with different hydroxy contents were constructed by implanting hydroxyl groups at the edges of coronene. The physical properties, atomic partial charges and pore size distribution of the modified activated carbon model were studied by molecular dynamics and giant canonical Monte Carlo simulation, and the kinetic characteristics and adsorption mechanism of toluene in modified activated carbon were further analyzed. The results showed that the introduction of hydroxyl can improve the adsorption capacity of activated carbon to toluene, and hydroxyl content significantly affected the adsorption capacity. At high relative pressure, the best concentration of the hydroxyl group was 39.4%, and when hydroxyl concentration exceeded this value, the adsorption amount of toluene decreased. The strong electronegative oxygen atom in the hydroxyl group of modified activated carbon and the hydrogen atom in the methyl of toluene were combined to form a Lewis acid-base pair, which led to a stable adsorption structure and then increased the adsorption capacity of activated carbon to toluene. At low relative pressure, the main factors affecting the adsorption capacity were porosity and pore size. The modified activated carbon with hydroxyl content of 20.8% and 31.4% had massive micropores and a relatively compact structure, which was favorable for toluene adsorption. The self-diffusion coefficient of the toluene molecule in activated carbon was decreased by hydroxyl modification, and the diffusion coefficient was the lowest in activated carbon containing 39.4% hydroxyl. This was because the non-bond interaction between the toluene molecule and modified activated carbon hindered the movement of the toluene molecule. In addition, according to the variable-temperature adsorption research, the increase in temperature was not conducive to the adsorption of toluene by activated carbon since it was an exothermic process. This study can provide a theoretical basis for the improvement of the adsorption performance of activated carbon materials. Related Articles | Metrics

Select

Application of lignin epoxy resin synthesized in aqueous phase in wood adhesive Yong WANG Yaqing YIN Qingyun LI Aixing TANG Lei ZHAO Youyan LIU The Chinese Journal of Process Engineering    2022, 22 (5): 671-679.   DOI: 10.12034/j.issn.1009-606X.221198 Abstract （481）      PDF （3898KB）（97）       Knowledge map    Save In this study, a lignin epoxy resin suitable for wood adhesive was synthesized in an aqueous phase by using lignin as raw material. To study the effect of reaction conditions of lignin epoxidation on the hydroxyl and epoxy groups of lignin-epoxy resin and the bonding strength of plywood, the structure of lignin-epoxy resin was characterized by FT-IR and 31P NMR, and the thermal stability of lignin-epoxy resin was analyzed by TG and DTG. The results showed that the epoxidation reaction mainly took place in the phenolic hydroxyl group. And in the process of epoxidation, the additional amount of NaOH exerted a greater effect on the structure of lignin epoxy resin and the bonding strength of plywood than that of epichlorohydrin. With the increase in the amount of NaOH added in the reaction process, the number of epoxy groups in lignin epoxy resin increased gradually and the bonding strength of plywood showed a trend of increasing firstly and then decreasing. When the molar ratio of a hydroxyl group to NaOH of lignin was 1:1, the bonding strength of plywood made of lignin epoxy resin can reach the maximum, and the wet strength can reach 1.61 MPa, which exceeded the requirements of class II board in Chinese national standard (≥0.7 MPa). SEM was used to study the bonding mechanism, it was found that the structure of cured lignin epoxy resin was more stable and compact when the degree of epoxidation was increased, which led to the improvement of the bonding strength of plywood. However, an excessively high degree of epoxidation will increase the particle size of the adhesive particles, resulting in the inability of the adhesive to form a good mechanical interlocking structure with the wood, thereby reducing the bonding strength of the plywood. Furthermore, the synthesis process of lignin epoxy resin wood adhesive was simplified, the epoxidized system can be directly applied to the wood adhesive, and after 30 days of storage, the bond strength did not decrease significantly. Besides, compared with commercial UF resin wood adhesive, the bonding strength of UF resin can reach the level of commercial UF resin. The results showed that this method may have a great application prospect in the wood adhesive industry. Related Articles | Metrics

Select

Theoretical design of new energy solid-state battery materials and development of battery technology under the background of carbon peaking and carbon neutrality Hongjie XU Guanghui WANG Yujie SU Zhigao ZHANG Haitong LI Zhongzheng YANG Yuchen WANG Linyue HU Guoqin CAO The Chinese Journal of Process Engineering    2023, 23 (7): 943-957.   DOI: 10.12034/j.issn.1009-606X.223113 Abstract （477）   HTML （14）    PDF （4779KB）（342）       Knowledge map    Save Rechargeable lithium metal batteries (LMBs) have attracted wide attention due to their high theoretical energy density and important applications in portable electronic devices, electric vehicles, and smart grids. However, the implementation of LMBs in practice still faces many challenges, such as low Coulombic efficiency, poor cycle performance, and complex interfacial reactions. An in-depth analysis of the physical basis and chemical science of solid-state batteries is of great significance for battery development. To confirm and supplement the experimental research mechanism, theoretical calculation provides strong support for exploring the thermodynamic and kinetic behavior of battery materials and their interfaces and lays a theoretical foundation for designing batteries with better comprehensive performance. In this review, the theoretical and structural design ideas of the Li10GeP2S12 system and argyrodite system in sulfide solid electrolytes are reviewed, including the transport mechanism and diffusion path of lithium ions. The theoretical design ideas of new anti-perovskite Li3OCl and double anti-perovskite Li6OSI2 electrolyte systems are analyzed. The transport mechanism of Li+ in oxide solid electrolyte systems under defect regulation is reviewed. In addition, the theoretical design of new halide electrolyte systems, and the role of computational materials science in the study of battery material properties are also introduced. The key issues such as ion transport mechanism, phase stability, voltage platform, chemical and electrochemical stability, the interface buffer layer, and electrode/electrolyte interface are analyzed by theoretical methods. Understanding the charge-discharge mechanism at the atomic scale and providing reasonable design strategies for electrode materials and electrolytes. Related Articles | Metrics

Select

Research progress on gas-liquid two-phase flow characteristics of bubble plume Xin DONG Yinuo LIU Chen YE Jianwei ZHANG Ying FENG The Chinese Journal of Process Engineering    2023, 23 (1): 15-24.   DOI: 10.12034/j.issn.1009-606X.222021 Abstract （470）   HTML （2）    PDF （1035KB）（259）       Knowledge map    Save Bubble plume is a complex gas-liquid two-phase flow, which is widely used in industrial fields such as wastewater treatment, petroleum processing, environmental protection. The complex flow characteristics of bubble plume are very important for gas-liquid mass, momentum transfer and its industrial application. In this work, the flow characteristics of bubble plume in theoretical and experimental research are analyzed and summarized. The effects of different operating and structural parameters on the hydraulic characteristics such as gas holdup, bubble size distribution, plume width and oscillation are discussed. The simulation methods of observing and capturing the flow characteristics of bubble plume are summarized. In addition, due to the wide application of bubble plume, it is also very important to measure the bubble velocity distribution quickly and accurately. With the rapid development of digital image recognition technology, the combination of high-speed camera and digital image recognition technology provides an effective, intuitive and accurate method for bubble plume velocity. The prediction models and empirical formulas of hydraulic parameters such as gas holdup and bubble diameter are summarized, and the different applicable conditions of the models and formulas are listed. In the practical application of bubble plume, the structural morphology and flow characteristics of bubble plume change due to the complexity of environmental fluid (such as transverse flow in environmental fluid and stratification due to density and temperature difference of environmental fluid). Therefore, the research progress of gas-liquid two-phase flow characteristics of bubble plume in complex environment fluid is presented. The variation of bubble plume flow pattern and the effect of plume destratification in stratified fluid are summarized. The migration behavior and motion of plume in transverse flow environment are analyzed. Finally, the limitations of research methods and theoretical methods of gas-liquid two-phase flow characteristics of bubble plume are discussed. The multi-scale research direction of bubble plume motion law is proposed in further. Related Articles | Metrics

Select

Research process of multivesicular liposomes Xing FAN Hua YUE Xiaojun WANG The Chinese Journal of Process Engineering    2023, 23 (10): 1371-1380.   DOI: 10.12034/j.issn.1009-606X.222431 Abstract （467）   HTML （16）    PDF （2032KB）（259）       Knowledge map    Save Since 1983, multivesicular liposomes (MVLs), as a member of the liposome family, have been of interest in the biomaterials and medical fields. MVLs have multiple aqueous compartments separated by phospholipid bilayers and an internal aqueous phase of up to 90%. They also have the advantages of reducing the number of injections, extending the duration of drug action, and improving patient compliance. So far, most of the MVLs reported in the literature are above 10 μm in size and have made good progress mainly in the encapsulation of analgesic drugs. This review provides an overview of the preparation methods, characterization methods, and drug release mechanisms of MVLs that have been reported in the literature in the last decade. There are relatively several methods for preparing MVLs, including the double emulsification method, spray atomization technique, and electroforming method. Currently, the main characterization methods used for MVLs are optical/fluorescent confocal imaging, scanning electron microscopy imaging, determination of particle size distribution, entrapment efficiency, and determination of zeta potential. Because of the large volume of the internal aqueous phase of MVLs and the high hydrophilic drug encapsulation rate of the internal vesicles, the individual vesicles gradually rupture and the hydrophilic drug gradually gets released during in vitro release, with a three-phase release pattern of sustained release. This review also summarizes the current status of clinical studies and types of commercialized products. At present, the application of MVLs regarding analgesics has reached stages II-IV, and three commercialized formulations have entered the clinic with satisfactory results. Moreover, this review summarizes the current progress in applied research, mainly in the delivery of anticancer drugs, analgesic drugs, and protein peptides. Last but not least, the challenge and prospects regarding small-sized MVLs, diverse biomedical applications, and scale-up strategies are proposed. Related Articles | Metrics

Select

Analysis and thinking of low-carbon technology in non-ferrous metal industry Shili ZHENG Shufeng YE Qian WANG Shuhua MA Zhi WANG Zhi SUN Shan QIAO Xiaomeng ZHANG Yi ZHANG The Chinese Journal of Process Engineering    2022, 22 (10): 1333-1348.   DOI: 10.12034/j.issn.1009-606X.222282 Abstract （463）   HTML （20）    PDF （3466KB）（197）       Knowledge map    Save Reduction of carbon dioxide emission in the non-ferrous metal industry is critical for realizing the carbon peaking and carbon neutrality goals in China. State-of-the-art of carbon dioxide emissions in the non-ferrous metal industry were summarized and analyzed here. Based on this, the low-carbon technology path of non-ferrous metal industry, especially the key smelting industry, was put forward. The analysis shows that the aluminum smelting industry is the core of carbon dioxide emission reduction in the non-ferrous metal industry. It is expected that the non-ferrous metal industry will achieve a peak of carbon dioxide emission in 2025 with the peak value being 750 million tons carbon dioxide. The carbon dioxide reduction technology path of the non-ferrous industry mainly includes four parts, which are, green energy substitution, advanced low-carbon technologies and equipment, metal recycling, and carbon capture and utilization (CCU). Among them, metal recycling is the key path for the non-ferrous industry to support the realization of the national carbon peaking and carbon neutrality goals. Related Articles | Metrics

Select

Research progress on high efficiency metallurgy and clean extraction of vanadium-titanium magnetite ore in Panxi area Chenguang BAI Xuewei LÜ Guibao QIU Shengfu ZHANG The Chinese Journal of Process Engineering    2022, 22 (10): 1390-1399.   DOI: 10.12034/j.issn.1009-606X.222302 Abstract （461）   HTML （17）    PDF （5487KB）（180）       Knowledge map    Save The vanadium-titanium magnetite ore is an important characteristic resource in Panxi area of China, but it is difficult to smelt because of its high TiO2 content and complex mineral phase. As early as June 1958, Mr. Chu-Phay Yap issued a written opinion on "urgent problems of iron ore bearing titanium in Panzhihua". Among them, the "urgent problem" is to break through some foreign scholars' judgment: "smelting this ore with blast furnace has little hope of success", and rely on domestic scientific research to overcome the problems of smelting vanadium-titanium magnetite ore with blast furnace in Panxi area. With the cooperation of related industries and research forces in China, it has been successfully broken through that difficult problem of smelting of vanadium-titanium magnetite ore with blast furnace in Panxi region, and further improved the level of smelting, reaching the world higher level in whole. In recent years, in addition to the continuous improvement of smelting level, the level of comprehensive utilization of that kind ore has also carried out a lot of original research work. Chongqing University is one of the earliest research institutes on comprehensive utilization of vanadium-titanium magnetite ore smelting. Over the years it has always took the vanadium-titanium magnetite smelting and its efficient utilization as the primary of metallurgical science research topic in the Chongqing University, and the unique processes of blast furnace smelting vanadium-titanium magnetite ore are studied systematically in the theory and technology, that has formed distinctive research features. In recent years, it has also been made that breakthroughs in theoretical and experimental research methods and made good progress in close cooperation with enterprises on smelting technology of high ratio vanadium-titanium magnetite ore in blast furnace, titanium extraction from titanium-containing blast furnace slag and titanium slag smelting technology in large electric furnace, as well as efficient and clean extraction technology of vanadium resources. This review gives a brief introduction on the clean metallurgy and efficient extraction research progress on Panxi vanadium-titanium magnetite ore in Chongqing University, to commemorate the contribution of Chu-Phay Yap and Yanxian Lin et al. scientific workers for the development and utilization of Panxi vanadium-titanium magnetite ore, and uphold their feet on the ground, as well as the innovation of scientific spirit. To promote the development of green and intelligent metallurgy and resource efficient utilization of vanadium-titanium magnetite ore in Panxi region under the carbon peaking and carbon neutrality goals. Related Articles | Metrics

Select

Optimization and scale?up of fermentation process for succinic acid production by Escherichia coli FMME-N-26 Jia LIU Wenxiu TANG Xueming WANG Liang GUO Xiulai CHEN Cong GAO Liming LIU The Chinese Journal of Process Engineering    2022, 22 (7): 853-862.   DOI: 10.12034/j.issn.1009-606X.221265 Abstract （458）   HTML （9）    PDF （1083KB）（187）       Knowledge map    Save Succinic acid is considered to be one of the most promising bulk chemicals produced by white biotechnology and has a wide range of applications in industry. Microbial production of succinic acid has the advantages of environmental friendliness, and sustainable development, showing a good development prospect. However, a few issues remain with microbial production of succinic acid, such as the low yield, by-products accumulation and low productivity. In order to achieve the efficient production of succinic acid by Escherichia coli (E. coli) FMME-N-26, the fermentation conditions and feeding strategy were optimized in a 3.6 L fermenter. The process involved a two-stage fermentation, with aerobic cell growth followed by anaerobic conditions for succinic acid production. The optimal fermentation conditions were as follows: aerobic fermentation was transitted to anaerobic fermentation at 8 h, MgCO3 was used as pH neutralizer, 2 mmol/L betaine was added as osmoprotectants at 72 h, and glucose concentration was controlled to be 1~5 g/L in the anaerobic stage. The yield of succinic acid and the yield of glucose in anaerobic phase reached 119.2 g/L and 1.08 g/g (97% of the theoretical yield) at 72 h after optimized fermentation, which were 46.4% and 4.8% higher than those of the original fermentation, respectively. Only 2.37 g/L and 0.94 g/L of acetic acid, and lactic acid were accumulated as by-products, which were 37.1% and 49.2% lower than those of the before optimized fermentation, respectively. Then the scale-up production was realized in a 1000 L fermentation tank. The production of succinic acid yield, glucose yield and production intensity by E. coli FMME-N-26 were leading level at home and abroad. Taken together, this study provides a solid foundation for the industrial production of succinic acid and the strategies described here also pave the way to the production of other value-added chemicals. Related Articles | Metrics

Select

Prospect of resource recycling technology frontier of metallurgical industry with carbon peaking and carbon neutrality strategy Huiquan LI Yufeng WU Yunfa CHEN The Chinese Journal of Process Engineering    2022, 22 (10): 1414-1417.   DOI: 10.12034/j.issn.1009-606X.222360 Abstract （456）   HTML （12）    PDF （503KB）（156）       Knowledge map    Save Resource recycling is an important way for the metallurgical industry to ensure the safe supply of key metal resources and achieve carbon peak and carbon neutrality. From the perspective of carbon peaking and carbon neutrality strategy, this work outlines the overall status and the development trend of green low-carbon transformation in the resource recycling of metallurgical industry, prospects the development frontier of resource recycling technology in the metallurgical industry from multiple perspectives such as the scientific basis of material recycling, the revolutionary technology of "waste free metallurgy", the coupling of resource recycling and carbon cycle, the high-quality recycle of secondary metal resources, and the reconstruction of intellectual property rights based on digital technology. A series of view points is proposed to be useful reference for the green and low-carbon transformation and development of metallurgical industry. Related Articles | Metrics

Select

Thermal simulation technique for solidification process of continuous casting and its application Huazhi YUAN Honggang ZHONG Qijie ZHAI The Chinese Journal of Process Engineering    2022, 22 (10): 1400-1413.   DOI: 10.12034/j.issn.1009-606X.222310 Abstract （455）   HTML （15）    PDF （5409KB）（102）       Knowledge map    Save Solidification is an important process governing the quality of metallurgical products, but the study of solidification process under continuous casting condition is extremely difficult result from the high temperature, opaque, large-scale and continuous production. The current research methods mainly include numerical simulation, physical simulation and thermal simulation, among which thermal simulation method is of great interest because the experimental data similar to the production conditions can be directly obtained. This work systematically introduces the methods of thermal simulation for continuous casting solidification. The principles of thermal simulation techniques are briefly described, and the applications of the mold thermal simulation method and the characteristic unit thermal simulation method are summarized. Among them, the thermal simulation methods for dendritic growth of continuous casting billet and hot tearing based on the heat conduction similarity have successfully "condensed" the solidification process of a dozen tons of cast billet into a laboratory study with 100 grams of steel. Both the methods can not only reveal the influences of composition, pouring and cooling conditions on solidification process, microstructure and solute distribution, but also can observe the morphology of solid-liquid interface, diffusion of solute, evolution of inclusions, and the possibility of hot tearing formation, that are regarded as extremely important issues in metallurgy filed but cannot be obtained by other means. Related Articles | Metrics

Select

CFD simulation of thermal runaway esterification reaction in stirred tank Biqing CHEN Xiaoping GUAN Ning YANG Dingrong BAI The Chinese Journal of Process Engineering    2022, 22 (8): 1053-1060.   DOI: 10.12034/j.issn.1009-606X.221317 Abstract （452）   HTML （9）    PDF （4055KB）（145）       Knowledge map    Save Thermal runaway is one of the common risks in chemical process safety. Thermal runaway accidents of various scales cause a lot of economic losses every year. The runaway of batch stirred reactor is particularly dangerous due to the single way to control the reaction rate.From the view point of intrinsic safety, optimal design of reactor and operating conditions can fundamentally prevent thermal runaway. In batch-operated stirred tank reactors, impeller rotation can enhance flow circulation, turbulence intensity, mixing degree, and heat transfer, thus effectively preventing thermal runaway. In this work, according to the esterification reaction of propionic anhydride and isopropanol to produce isopropyl propionate and propionic acid under the catalysis of concentrated sulfuric acid, CFD simulation was carried out to simulate the thermal runaway esterification reaction in stirred tanks. The effects of impeller type (Rushton impeller, 30° pitched blade turbine impeller and 60° pitched blade turbine impeller), rotation direction, and baffle on the temperature evolution were studied. The simulated flow structures were used to explain the effects. Furthermore, divergence criterion was used to compare the performance of resisting thermal runaway for different impellers. The simulation showed that the radial flow agitator performed better than the axial flow agitator at the same rotation speed, and the performance order was Rushton impeller>30° PBTD impeller>60° PBTD impeller. For the 30° PBT impeller, when the operating mode changed from PBTD to PBTU, the capability to resist thermal runaway weakens, though the number of circulation zone increased. The situation of 60° PBT impeller was similar to that of 30° PBT impeller. The addition of baffle can substantially improve the thermal control in the reactor. This research provided fundamentals for design, optimization, and scale-up of reactors. Related Articles | Metrics