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    28 January 2022, Volume 22 Issue 1
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    Cover and contents
    The Chinese Journal of Process Engineering. 2022, 22(1):  0. 
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    Reviews
    Research progress on photocatalytic treatment of residual xanthate in mineral processing wastewater and improvement of degradation efficiency
    Rui LIANG Mingyang LI Xiangpeng GAO Xiankun YU Xiong TONG Hongming LONG
    The Chinese Journal of Process Engineering. 2022, 22(1):  1-13.  DOI: 10.12034/j.issn.1009-606X.220436
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    Degrading the residual xanthate efficiently, environmentally, and economically in the mineral processing wastewater is a major problem needing to be solved urgently in the process of building a green mine. Photocatalytic degradation of xanthate in flotation wastewater is an environmentally friendly wastewater treatment process. It has many advantages, such as simple and convenient operation, wide application range, mild reaction conditions, free secondary pollution, etc. This work focuses on the application of photocatalytic degradation methods and reviews the research progress of photocatalysts of xanthate in recent years. It mainly introduces the research overview of photocatalysts according to the different classifications of photo-catalytic materials and their modification methods, and then explores the reaction mechanism and related influencing factors of photocatalytic degradation of xanthate. Moreover, improvement methods based on the factors affecting the degradation rate of photocatalysts are proposed. In the end, the design and process development of catalysts for photocatalytic degradation of xanthate were prospected. The photocatalytic materials currently used in the degradation of xanthate are mostly derived from metal semiconductors, including titanium, bismuth, zinc, copper, tungsten, iron-based compounds, and their modified substances, as well as non-metal semiconductor g-C3N4 and HAP-based photocatalyst. The ultimate goal of studying photocatalytic technology is to treat pollutants efficiently and environmentally. Therefore, how to improve the degradation efficiency is the core issue of the study. The existing literature mainly uses degradation conditions and photocatalysts to determine the factors affecting degradation efficiency and proposes targeted improvements. In addition, to make up for the shortcomings of a single photocatalyst, a combined process will be adopted to maximize the photocatalytic degradation efficiency.
    Research Paper
    Experimental research on influence of refrigerant charge on heat transfer characteristic of micro-channel evaporator
    Jinli LU Tingting YIN Yafang HAN Yajin LIU
    The Chinese Journal of Process Engineering. 2022, 22(1):  14-21.  DOI: 10.12034/j.issn.1009-606X.220342
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    With the advantages of compact structure, small size, high heat exchange efficiency, and low refrigerant charge, the microchannel heat exchanger has broad application prospects in the fields of electronic components, automobiles, heat pumps, air conditioners, etc. According to the literatures, the microchannel heat exchangers are currently used more in electronic components and automobiles, but less in household air conditioners. Therefore, the microchannel heat exchanger was designed and produced based on aluminum materials and employed as evaporator of cabinet air conditioning. The surface temperature distribution, cooling capacity, input power, and energy efficiency ratio (EER) were researched under the conditions of three inlet types (Z-Inlet, Y-Inlet, U-Inlet) and five refrigerant charges (in the range of 800~1600 g). Furthermore, the results were compared with the finned-tube evaporator which was composed of cooper tubes and aluminum fins. The results showed that the Z-Inlet type had uniform flow rate distribution, uniform surface temperature distribution, and excellent heat transfer performance because of the same length of the flow inside of microchannel evaporator. The Z-Inlet type of microchannel evaporator had the highest cooling capacity and EER. Compared with the other two type (Y-Inlet, U-Inlet), the cooling capacity and EER increased by a maximum of 8.8% and 5.7%, respectively. The cooling capacity and EER of microchannel evaporator were significantly higher than that of finned-tube evaporator, with an average increase of 11%, and a maximum of 13.3% (about 600 W). And the EER increased by an average of 9.36%, and a maximum of 12.4%. In addition, compared with finned-tube evaporator, the refrigerant charge of microchannel evaporator can be reduced by 200 g when the cooling capacity and EER with the maximum value. Therefore, the research results of this work can provide data support for the development and design of microchannel evaporators, optimization of operating parameters, and support the application of microchannel evaporators in the field of air conditioning.
    The baffle structure optimization for high and low side?by?side type RFCC stripper
    Biao LIU Xiuying YAO Zhenliang MENG Mengxi LIU
    The Chinese Journal of Process Engineering. 2022, 22(1):  22-31.  DOI: 10.12034/j.issn.1009-606X.220397
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    A stripper is an important part of a fluid catalytic cracking (FCC) plant, affecting products yields, energy consumption and long-term run of the entire unit greatly. A high-efficiency stripper increases the light oil yield and improves the product distribution, moreover, it also reduces the coke-burning load of regenerator and decreases the hydrothermal deactivation of catalyst. Strippers widely used in fluid catalytic cracking units can be categorized into the packing stripper and the baffle stripper. The former owns the advantages of high stripping efficiency and better space utilization, but is not suitable for residue fluid catalytic cracking (RFCC) units, because the grid is easily blocked up with coke and difficultly cleaned. Therefore, the latter is widely used in RFCC units, benefited from simple structure, high stripping efficiency and long-term operation. Hydrodynamic characteristics of gas phase and solid phase in a commercial stripper with perforated baffle is rarely studied, subject to severe experiment condition and poor measurement methods. In this work, hydrodynamic behavior of the steam and particles in a commercial-scale fluid catalytic cracking stripper is investigated numerically, by using two-fluid model with a drag model which divides the flow region into four parts: dese, sub-dense, dilute and ultra-dilute. The mean bed density from the simulation is in good agreement with the value registered in a commercial unit. Calculation results demonstrate that strict S-shape flow of steam does not exist in stripper. Steam short circuit between the neighboring annular baffles or conical baffles occurs in the region of 0.85<r/R<1 or 0.35<r/R<0.5, respectively. Radial distribution of catalyst concentration above the baffle is uneven. The steam flux of holes on baffles reduces with the decrease in the vertical position of holes, explaining why the phenomena of the gas short circuit appears. Based on the above findings, a new baffle was proposed and adopted in order to distribute steam reasonably. Simulation results show that the steam short circuit is significantly weakened, leading to a smooth catalysts flow above the baffle and an excellent gas and solid contact.
    Simulation of gas-liquid flow and structure optimization in scrubbing-cooling chambers
    Yang LIU Zhongshan GUO Yuanqi ZHAO Xiaoping GUAN Ning YANG
    The Chinese Journal of Process Engineering. 2022, 22(1):  32-40.  DOI: 10.12034/j.issn.1009-606X.221040
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    The scrubbing-cooling chamber is an important part of a coal gasifier to wash and cool the generated high-temperature syngas. It is composed of a vertical pipe and the liquid bath. However, some technical problems still exist in industrial-scale scrubbers, such as unstable operation, lower washing efficiency, all of which are relevant to gas dispersion in scrubbers. It is of great significance to design a scrubbing-cooling chamber with higher washing efficiency. Due to the difficulty of transforming the scrubbers on an industrial-scale, the CFD simulations were used to understand the complex gas-liquid flow in different structures of scrubbing-cooling chambers and to provide theoretical guide for industrial design and process scale-up. In this work, a new scrubber which combined of branch pipes and a draft tube on the basis of the general scrubbers was proposed to promote gas dispersion and a three-dimensional Euler-Euler two-fluid model was used to simulate the flow behavior in three different scrubber geometry, i.e., no-internals, branch pipes attached on the vertical pipe, a combination of branch pipes and a draft tube. Gas holdup, liquid flow field and gas distribution were compared among the three different geometries. Comparison between the simulation and the experiments in literature showed that the model can accurately predict the gas holdup distribution. Furthermore, simulations indicated that the added branch pipes diverted a portion of gas to the central region of the chambers, which may otherwise be entrained along the wall of the central pipe. The branch pipes promoted the radial dispersion and was helpful to maintain stable operation. Further installation of a draft tube enhanced the amount of gas transported by the branch pipes, and increased the global gas holdup under the liquid surface of the scrubber. It was found that the combination of the branch pipes and the draft tube can effectively intensify gas-liquid circulation and interfacial contact, and improve the washing efficiency.
    Large eddy simulation of inclined interface instability induced by planar shock wave
    Yongkang GUAN Yi LIU Lite ZHANG
    The Chinese Journal of Process Engineering. 2022, 22(1):  41-49.  DOI: 10.12034/j.issn.1009-606X.221057
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    Interfacial instability and its induced interfacial deformation and turbulent instability are widely used. In medium characteristic scale supersonic combustion, the interfacial instability enhances the mixing of fuel and combustion aids. In small characteristic scale inertial confinement fusion, the turbulent mixing induced by interfacial instability dilutes and cools the fuel twice, thus reducing the reaction rate and even causing ignition failure. In recent years, scholars at home and abroad have deeply studied the interaction between the classical planar shock wave and the phase interface from many angles, but the research on the interaction between the shock wave and the gas-liquid oblique interface is still not systematic and comprehensive. It is of great significance to explore the evolution of shock driving gas-liquid interface instability in practical engineering applications such as supersonic combustion and inertial confinement fusion. In the process of numerical simulation, VOF model is used, combined with large eddy simulation method and appropriate boundary conditions to study the evolution process of shock induced gas-liquid two-phase oblique interface deformation and turbulent mixing in two-dimensional plane. The influence of Mach number of incident shock, initial inclination angle of shock and inclined interface inclination angle on interface instability is analyzed. The results show that the Mach number of incident shock is the most important factor in the development of interface instability. Under the same conditions, compared with the other two factors, increasing the shock Mach number can significantly increase the interface deformation and the development of turbulent mixing. At the same time, the number of serrated structures on the interface increases, the forming speed is obviously accelerated, and the width of turbulent mixing zone increases obviously. In addition, with the increase of the initial angle of shock wave and inclined interface angle, the number and forming speed of serrated structure on the interface increase at the same time, and the width of turbulent mixing zone also increases.
    Numerical simulation analysis of particle concentration field in a super vortex quick separation system under different oil steam parameters
    Zhiliang ZHANG Haijun CHEN Tao CHEN Pei MOU Anjun LI Wenjun LI
    The Chinese Journal of Process Engineering. 2022, 22(1):  50-61.  DOI: 10.12034/j.issn.1009-606X.221092
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    In order to investigate the movement and concentration distribution characteristics of catalyst particles in the riser outlet super vortex quick separation (SVQS) system, the gas-solid two-phase flow under different oil steam parameters was numerically simulated. Whereafter, particle size, concentration distribution and particles back mixing were analyzed. The simulation result showed that under a certain entrance concentration the particle concentration on the wall of the closing cylinder was greater with the greater density of oil steam or the smaller viscosity of oil steam, and distributed in a spiral strip with different bandwidth. A large number of particles gathered at the cover plate of the flow partition cylinder and formed a particle belt with periodic shedding characteristics. Moreover, the phenomenon of short circuit flow at the bottom of flow partition cylinder that weakened the separation performance of SVQS system. Particles with different sizes were always in a spiral layered arrangement when moving in a downspin, and the separation performance of SVQS system for fine particles with diameter below 0.013 mm was weak. With the increase of oil steam density or the decrease of viscosity, the particles following behavior became better, the particles concentration distribution was more uniform, and the SVQS system had a stronger ability to capture medium and fine particles. Particles back mixing also existed in SVQS system and decreased with the increase of oil steam density or the decrease of viscosity. Meanwhile, reducing particle back mixing and inhibiting particle concentration peak were important ways to improve the separation performance of the system.
    Modification behavior of Sb in electromagnetic separation process of high silicon aluminum silicon alloy
    Xiongdong YANG Junpeng WANG Wenhui MA Guoqiang LÜ Aimin XING
    The Chinese Journal of Process Engineering. 2022, 22(1):  62-71.  DOI: 10.12034/j.issn.1009-606X.220401
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    Aimed at the electromagnetic separation process of high silicon aluminum silicon alloy, addition of the modifier Sb in the separation process was proposed to and the effects of the addition amount of the modifier Sb, the pull-down rate, and the temperature on the separation effect in the electromagnetic separation process of the high silicon aluminum silicon alloy (45wt% Si) to strengthen the separation of primary silicon and alloy were studied. In the early stage of the directional solidification process, the modification experiment was carried out to perform XRF detection and FEI-SEM scanning of the silicon content in the primary silicon enrichment area of the sample, and the EPMA analysis of the micro morphology of the alloy part. Later, referred to the Sb modification mechanism in the relevant literature, Comsol software was used to simulate the electromagnetic directional solidification process of Al-45wt% Si. The separation theory of primary crystal silicon and the theory of silicon grain refinement were used to discuss the metamorphic behavior of Sb. After the addition of Sb, the eutectic reaction temperature of the aluminum-silicon alloy decreased and the entire solidification process became longer. Theoretically, the primary crystal silicon can obtain more sufficient growth conditions, which was beneficial to the enrichment of the primary crystal silicon. The results showed that after adding the modifier at 1500℃, when the pull-down rate was 10 μm/s, the silicon content in the silicon-rich phase increased from 86wt% to 90wt%. When the pull-down rate was 40 μm/s, the silicon content in the silicon-rich phase increased from 81wt% to 86.5wt%. At the same time, after adding the modifier, the eutectic silicon phase of the alloy was uniformly and continuously distributed in the α-Al matrix, and the morphology was refined.
    Improved sodium storage performance of layered oxide cathode materials via ZrO2 coating
    Yang SUN Hong WANG Haiying CHE Xiaozhen LIAO Linsen LI Guijia CUI Weimin YANG Zifeng MA
    The Chinese Journal of Process Engineering. 2022, 22(1):  72-78.  DOI: 10.12034/j.issn.1009-606X.220379
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    Lithium ion batteries have been successfully applied in portable electronic products, the application of lithium ion batteries is expanding to the fields such as large scale energy storage grid and electric vehicles. However, the considerably increased demand of lithium ion batteries might yield problems in the future with the limit of Li resources. Compared with lithium, sodium is abundant in the earth. Based on its resource and cost advantages, sodium ion batteries hold promise for low-cost energy storage and could be key for smart electric-grid of the future. To date, a large variety of cathode materials with satisfactory performance have been proposed. These cathode materials include layered transition metal oxides, Prussian blue analogues, polyanionic-type compounds and organic-based materials. Layered transition metal oxides NaxMO2 (M=Mn, Fe, Ni, Co, Ti, V, Cr) have been extensively investigated because of their higher capacities and industrial feasibility. Up to now, layered transition metal oxide NaNi1/3Fe1/3Mn1/3O2 has been established as a promising cathode materials for practical sodium ion batteries. Many works have also focused their efforts on NaNi1/3Fe1/3Mn1/3O2 over the years and studied its synthesis method, large scale synthesis, electrochemical reaction mechanism, coating, doping and thermal stability. In this work, ZrO2 coating NaNi1/3Fe1/3Mn1/3O2 cathode was prepared by a solid state method, and the coating effect was evaluated by electrochemical measurements as well as morphological, structural, and chemical composition analyses. The results showed that ZrO2 formed an inert protective layer on the surface of NaNi1/3Fe1/3Mn1/3O2, which effectively separated the contact between electrolyte and cathode material, alleviated the decomposition rate of electrolyte and inhibited the dissolution rate of metal ions, so as to significantly improve the cycle performance and high temperature performance of the battery. After ZrO2 coating modification, the cathode material was significantly improved compared with the uncoated cathode material at 55℃, and the capacity retention rate reached 83.6% after 100 cycles, which was higher than 75.2% of the uncoated cathode material. In addition, the stability of the coated NaNi1/3Fe1/3Mn1/3O2 cathode material was significantly improved after storage in air environment.
    Study on preparation and performance of mullite-corundum catalyst carrier
    Jianlin YANG Lu ZHAO Shuhua MA Xiaohui WANG Yuejiao WANG
    The Chinese Journal of Process Engineering. 2022, 22(1):  79-88.  DOI: 10.12034/j.issn.1009-606X.220381
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    In order to realize the resource utilization of high-aluminum fly ash and alleviate the huge demand for catalyst carriers, this work developes a new process. That is, using Chinese characteristic high-alumina fly ash as raw material, the mullite-corundum catalyst carrier is prepared by the acid-alkali combined method, and a series of characterization methods such as specific surface automatic physical adsorption instrument (BET), scanning electron microscope (SEM), X-ray diffractometer (XRD), inductively coupled plasma mass spectrometer (ICP-OES) are used for in-depth analysis. The results show that when the acid-alkali combined process is adopted, that is, the acid process conditions are sulfuric acid concentration 1.5 mol/L, the reaction temperature 85℃, liquid-to-solid ratio 7, and the reaction time 90 min; subsequent pretreatment alkali process conditions are NaOH concentration 200 g/L, reaction temperature 95℃, liquid-to-solid ratio 15, and reaction time 150 min, the leaching rate of silica reaches 58.51%, and the leaching rate of amorphous silica is 83.49%. The obtained catalyst carrier with mullite and corundum as the main components has a higher specific surface area and water absorption. They are 39.35 m2/g and 70.01%, respectively. Its heat-resistant temperature reaches 1100℃, revealing that it has the advantages of good heat stability. From the SEM pictures, it can be seen that particle size is between 20~50 μm, and porous spherical structure is bonded by short rods. The X-ray diffraction characterization results show that the carrier mineral phase contains only mullite and corundum, indicating that it has good chemical stability and mechanical strength. The pore distribution analysis results reveal that the catalyst carrier has a wide pore size distribution, and the pore size is mainly 10 nm around. A mullite-corundum catalyst carrier with excellent performance has been prepared successfully, as finding a new way for the high-value utilization of secondary resource fly ash.
    Preparation of tannic acid-dopamine coating nanofiltration membrane for dye separation
    Qin JIANG Ziyu LIU Sui ZHAO
    The Chinese Journal of Process Engineering. 2022, 22(1):  89-96.  DOI: 10.12034/j.issn.1009-606X.221041
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    The tannic acid (TA)-polyvinylidene fluoride (PVDF) nanofiltration membrane is prepared by simply coating tannic acid and polydopamine. The chemical elements and morphology of the nanofiltration membrane surface are characterized by infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Meanwhile, the hydrophilicity and underwater anti-oil-adhesion performance of the modified membrane are also evaluated. Besides, the separation performance for dyes such as Direct red, Evans blue, Congo red, Reactive yellow, and Brilliant blue is explored. The result shows that the surface roughness of the obtained membrane increases slightly after modification. With the increase of TA concentration, the hydrophilicity of the membrane surface is significantly enhanced. When the TA concentration reaches 2wt%, the surface hydrophilicity of the prepared TA-PVDF nanofiltration membrane is almost stable, and the water contact angle of the modified membrane is 44.6°. Additionally, the obtained membrane with the underwater oil contact angle of 157.2° is characterized as a superoleophobic one. There is a strong interaction between the modified membrane and water molecules. On account of the hydration layer formed on the membrane surface, the obtained membrane can completely resist the contamination of oil under the water. The rejection rate of 2wt% TA-PVDF nanofiltration membrane is more than 96.5% for several dyes, and its permeating fluxes of Direct red, Evans blue, Congo red, Reactive yellow, and Brilliant blue all exceed 65.7 L/(m2?h?bar). In addition, the modified membrane keeps the permeance nearly unchanged during the dyes' separation process, exhibiting strong stability for dyes separation. Compared to the works published recently, the prepared nanofiltration membrane with 97% rejection rate for Congo red has a higher permeating flux. The obtained membrane shows a superior separation capacity and efficiency for the dyes, demonstrating a good application prospect in industrial dye wastewater separation.
    Ketopantoate production from glucose by combining biological and chemical steps
    Yao YAO Xiyang LU Lin SHU Qinghui WANG Shaoqi SUN Jian HAO
    The Chinese Journal of Process Engineering. 2022, 22(1):  97-107.  DOI: 10.12034/j.issn.1009-606X.221036
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    D-pantothenic acid (vitamin B5) is an essential vitamin to animals and has large markets in the feed, cosmetics, and pharmaceutical industries. The biochemical role of D-pantothenic acid in all organisms is to form the core of the structure of coenzyme A. Biosynthesis of coenzyme A from pantothenate occurs in all organisms, while the synthesis of D-pantothenic acid is absent from animals. Thus D-pantothenic acid is an essential nutrient to animals. Ketopantoate is an intermediate of pantothenate biosynthesis pathway. Ketopantoate can be stereoselectivity converted to D-pantoic acid and further used for D-pantothenic acid production. However, the economic production of ketopantoate is a bottleneck of D-pantothenic acid production from ketopantoate. Hence, this study provided a novel method for synthesis of ketopantoate by aldol reaction of α-ketoisovalerate and formaldehyde, and α-ketoisovalerate was produced from fermentation with glucose as the raw material. 25.2 g/L α-ketoisovalerate was produced by an engineering Klebsiella pneumoniae strain with glucose as the main carbon source. 19.9 g/L Ketopantoate was synthesized from formaldehyde and α-ketoisovalerate by an aldol reaction at basic conditions. The reaction parameters of reaction were optimized and a conversion ratio of 83.5% was obtained at reaction conditions of pH 13 and 45℃. The ketopantoate in the solution was converted to ketopantoyl lactone at acidic conditions of pH<3. Ketopantoyl lactone was extracted to isobutanol with an extraction rate of 50.9%. The organic phase was decolourized, and ketopantoyl lactone crystal was obtained after concentration. Ketopantoyl lactone was converted back to ketopantoate in an aqueous solution in the pH range of 7~10, and ketopantoate crystal was obtained after concentration. Ketopantoate production from glucose via α-ketoisovalerate as an intermediate was set up, which suggested a novel and competitive technical route to produce ketopantoate. The whole processes were combinated biological fermentation and chemical reactions and had a high conversion ratio. This method adopted renewable and cheap original materials rather than highly toxic raw materials. The optimal temperature of the reaction was 45℃, which was in mild conditions. Overall, a novel and promising method for ketopantoate and ketopantoyl lactone production was provided.
    Fluoride migration in the aluminum extraction process of roasting secondary aluminum dross with ammonium sulfate
    Binghong LEI Honghui LIU Di ZHANG Yuming DONG Hongling ZHANG Taiping LOU Hongbin XU
    The Chinese Journal of Process Engineering. 2022, 22(1):  108-117.  DOI: 10.12034/j.issn.1009-606X.220402
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    Recovery of aluminum from secondary aluminum dross by roasting with ammonium sulfate and leaching with water is one of the most important methods to harmlessly utilizing secondary aluminum dross. However, fluoride leaching toxicity of the leaching residue should satisfy the national standard's prescription (the mass concentration of inorganic fluoride is less than 100 mg/L). Thus, it is necessary to study the F migration in the Al extraction process of roasting secondary aluminum dross with ammonium sulfate and leaching with water. In this work, the regularities about migration and transformation of F in the process of extracting Al from secondary aluminum dross via roasting with ammonium sulfate and leaching with water was investigated by fluoride ion electrode, XRD, XPS, SEM and XRF. The results showed that prolonging the roasting time, elevating the roasting temperature and increasing the mass ratio of ammonium sulfate to secondary aluminum dross could accelerate the migration of F from secondary aluminum dross to roasting off-gas. Additionally, extending the leaching time, increasing the leaching temperature and increasing the liquid-to-solid ratio was beneficial to reduce the content and proportion of F in the leaching residue. About 43.85% of F released from secondary aluminum dross to roasting off-gas in the form of gas, 23.92% of F went into the leaching solution as fluorine ion, and 32.23% of F remained in the leaching residue in the forms of AlF3 and AlF3?3H2O under the most suitable conditions with the roasting temperature of 450℃, the roasting time of 2 h, the mass ratio of ammonium sulfate to secondary aluminum dross of 6:1, the leaching temperature of 85℃, the leaching time of 80 min, and the liquid-to-solid ratio of 6:1. Ammonium sulfate could be recovered from roasting off-gas by spraying after defluorination. Moreover, polyaluminum sulfate as a water treatment agent could be prepared from the leaching solution with the removal of F. The leaching toxicity of the leaching residue was accorded with the national standard.
    Formation and dissociation characteristics of methane hydrate and distribution of ions in montmorillonite contained saline solution
    Hao CHEN Zelin XU Kefeng YAN Xiaosen LI Zhaoyang CHEN Gang LI Chungang XU
    The Chinese Journal of Process Engineering. 2022, 22(1):  118-126.  DOI: 10.12034/j.issn.1009-606X.221044
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    Natural gas hydrate accumulation and exploitation is a research focus on the development and application of new energy. However, a group of key issues involving the formation and dissociation characteristics of natural gas hydrate in marine sediments and the effect of salt ions on the hydrate stability remains to be solved. Based on the in situ sampling technique, the formation and dissociation processes of methane hydrate in montmorillonite contained saline solution was explored by in situ scanning electron microscopy and energy dispersive spectrometry. Furthermore, the morphology and ion distribution of methane hydrate during the formation and dissociation processes in montmorillonite adsorbing 0.5 mol/L NaCl solution were systematically analyzed. The results showed that the element distribution changed obviously during the hydrate formation and dissociation processes. NaCl was located on the boundary between hydrate granules caused by the salt-removing effect of hydrate formation and existed as the form of hydrated salt ions. Na+ and Cl- were distributed on the surface of montmorillonite as different layers. The surfaces of montmorillonite present the structure of independent granular while methane hydrate was formed. After the hydrate dissociation, the surfaces of montmorillonite sunk and formed some tiny gas channels. At the same time, the packing structures of montmorillonite were changed. The research demonstrated that the processes of hydrate nucleation, growth, and decomposition took place independently on the special unit between particles. Those processes had a closed relationship with the unit cell structure of hydrate.
    Global optimization of water network in the steel industrial park driven by the strategy of whole process pollution control
    Yuehong ZHAO Yongbing XIE Hongbin CAO Hao WEN
    The Chinese Journal of Process Engineering. 2022, 22(1):  127-134.  DOI: 10.12034/j.issn.1009-606X.220373
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    As a high water consumption industry, water conservation is one of the challenges needed to be conquered in order to achieve the sustainable development for Chinese iron and steel industry. Based on the idea of Whole Process Pollution Control (WPPC), global optimization of water network in the steel industrial park was carried out in this work. Firstly, the configurational and operational characteristics of the water network in the typical steel industrial park were investigated, and a multi-scale modeling method was proposed to describe the water network. Wherein different scale water systems, including water-use/treatment unit, process-scale water network, park-scale water network, and their interactions were discussed. Secondly, a superstructure was built to represent all possible water network configurations. Thirdly, an optimization model tailored for the steel industrial park was set up with the aim of minimizing the comprehensive water-use cost. The water conservation and pollutants balance of different scale water systems, together with some limits on structure and operation of the water network, were described as constraints. Lastly, to validate the proposed model, global optimization of water network in a steel industrial park with 5 million tons of crude steel production capacity per year was studied by constructing and solving the mathematical model. The results of study cases showed that the case driven by WPCC strategy achieved the best performance compared to other cases, i.e., lowest comprehensive water-use cost and lowest fresh water consumption. Compared to the current water-use index of the studied park, the index of the case driven by WPCC decreased by more than 20% at least. In terms of the results, the case studies also indicated the applicability of the proposed multi-scale optimization model, and all these data can help the steel industrial park to make decisions for implementing global optimization of water network.
    Chemical process fault diagnosis method based on extreme deep factorization machine
    Yadong HE Zhuang YUAN Yang LIN Xinjiang GAO Chuankun LI Chunli WANG
    The Chinese Journal of Process Engineering. 2022, 22(1):  135-144.  DOI: 10.12034/j.issn.1009-606X.221071
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    The chemical process fault detection and diagnosis technology represented by deep learning has become one of the main ideas to solve the problem in the industry. However, the existing deep learning diagnosis methods only focus on the non-linear high-order interactive features when constructing training models and ignore the complementary of linear features and low-order interactive features to global modeling. In addition, the high-order features extracted by the existing deep models involve only implicit interactive features, whose feature forms are unknown and uncontrollable in order. Based on these problems, this work proposes a extreme deep factorization machine-based fault diagnosis method for chemical processes, which achieves automatic extraction and efficient integration of high-order, low-order and linear features by parallel fusion of three different types of network models (factorization machine, deep neural networks and compressed interaction network). First, the selected data are sequentially subjected to preprocessing operations such as Z-score normalization, label annotation, and format conversion to convert the input data into the format data required by the model. Then, the format data are simultaneously input to the three neural network models to help train the proposed diagnostic model in parallel. Finally, the fault diagnosis results are output based on the optimal diagnosis model. From the perspective of single-fault diagnosis and multi-fault hybrid diagnosis, extensive comparison experiments are conducted on the Tennessee-Eastman process (TE) simulation dataset, and the results show that the proposed method has significant advantages over previous fault diagnosis methods in terms of metrics such as precision and recall rate.