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Experimental investigation of the mixing efficiency via intensity of segregation along axial direction of a rotating bar reactor

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中国化学工程学报:英文版 2023年第7期59卷 153-159页

作者： Abdelgadir Bashir Banaga Yan-Bin Li Zhi-Hao Li Bao-Chang Sun guang-wen chu State Key Laboratory of Organic-Inorganic Composite Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China Department of Chemical Engineering Tiangong UniversityTianjin 300387China

As a significant index to evaluate the mixing efficiency,studying the concentration distribution is directly related to the intensity of segregation(I_(s)).In this work,the I_(s) of the mixture composed of NaCl solutionwater was investigated experimentally in a rotating bar reactor(RBR)by the conductivity *** results showed that the mixing efficiency was improved along the axial direction from the bottom to the top in the *** concentration distribution at the bottom section was more uneven,and I_(s) was higher compared with the top section,which decreased from 6.53×10^(-5)to 1.57×10^(-7).With the increase of rotational speed from 0 to 700 r·min^(-1),I_s at the bottom and top sections decreased from 4.27×10^(-3)to 7.10×10^(-5)and from 1.93×10^(-3)to 7.29×10^(-7),*** increases flow rate of solution A,and the decreases of concentration of NaCl and flow rate of solution B gave rise to the reduction of I_(s),signifying an improved mixing *** results revealed that the conductivity method used in this paper has high efficiency and low cost to measure the I_(s),which indicates a promising prospect for estimating reactors'mixing performance.

关键词： Intensity of segregation Mixing efficiency Rotating bar reactor Conductivity method Concentration distribution

Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

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Frontiers of Chemical Science and Engineering 2022年第11期16卷 1672-1680页

作者： Hai-Long Liao Lan Jiang Hai-Xin Yu Zhi-Hao Liu Ji-wen Fu guang-wen chu Yong Luo State Key Laboratory of Organic–Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

Droplet impacting on the stainless steel wire mesh is very common in chemical devices,like a rotating packed *** wettability of wire mesh significantly affects the liquid flow pattern and liquid dispersion ***,the effect of surface wettability on the impaction phenomena at microscale such as liquid film is still *** this work,the dynamic behavior of liquid film on the surface of wire mesh was analyzed by computational fluid dynamics *** dynamic behavior of liquid film on the surface of wire mesh can be divided into the following three steps:(1)spreading step;(2)shrinkage process;(3)stabilizing or disappearing *** of surface wettability,as well as operating conditions,on wetting area and liquid film thickness were *** to the hydrophilic wire mesh,the final wetting area of hydrophobic wire mesh is zero in most *** average liquid film thickness on the surface of hydrophilic wire mesh is 30.02–77.29μm,and that of hydrophobic wire mesh is 41.76–237.37μ*** work provided a basic understanding of liquid film flow at microscale on the surface with various surface wettabilities,which can be guiding the packing optimization and design.

关键词： stainless steel wire mesh computational fluid dynamics surface wettability liquid film impacting

Chemical probe systems for assessing liquid–liquid mixing efficiencies of reactors

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Frontiers of Chemical Science and Engineering 2023年第10期17卷 1323-1335页

作者： Yi-Dong Zhang chun-Liu Zhang Liang-Liang Zhang Bao-Chang Sun guang-wen chu Jian-Feng Chen Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

Liquid-liquid mixing,including homogeneous and heterogeneous mixing,widely exists in the chemical *** to quantitatively characterize the mixing performance is important for reactor assessment and *** a convenient and direct method for mixing characterization,the chemical probe method uses some special test reactions to characterize the mixing ***,the working principle and selection requirements of this method are introduced,and some common chemical probe systems for homogeneous and heterogeneous mixing processes are *** characteristics and applications of these systems are ***,the development of the new system is proposed.

关键词： mixing chemical probe liquid-liquid heterogeneous

Computational fluid dynamic simulation of gas-liquid flow in rotating packed bed:A review

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Chinese Journal of Chemical Engineering 2022年第1期35卷 85-108页

作者： wen-Cong Chen Ya-Wei Fan Liang-Liang Zhang Bao-Chang Sun Yong Luo Hai-Kui Zou guang-wen chu Jian-Feng Chen Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China StateKey Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

The rotating packed bed(RPB)has been widely used in gas-liquid flow systems as a process intensification device,exhibiting excellent mass transfer enhancement ***,the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment *** the past two decades,Computational fluid dynamics(CFD)has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor *** article covers the development of the CFD simulation of gasliquid flow in ***,the improvement of the simulation method in the aspect of mathematical models,geometric models,and solving methods is ***,new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed,including pressure drop,velocity distribution,flow pattern,and concentration distribution,*** new phenomena such as the end effect area with the maximum turbulent have been revealed by this *** addition,the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different *** defects of current research and future development directions are also discussed at last.

关键词： Rotating packed bed Computational fluid dynamics Simulation Hydrodynamics Mass transfer

NO_(x) removal by non-thermal plasma reduction:experimental and theoretical investigations

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Frontiers of Chemical Science and Engineering 2022年第10期16卷 1476-1484页

作者： Yue Liu Ji-Wei Wang Jian Zhang Ting-Ting Qi guang-wen chu Hai-Kui Zou Bao-Chang Sun State Key Laboratory of Organic–Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China Daqing Refining&Chemical Company PetroChina Co.Ltd.Daqing 163411China

Green and efficient NO_(x)removal at low temperature is still ***_(x)removal via non-thermal plasma(NTP)reduction is one of such *** work presents the experimental and theoretical study on the NO_(x)removal via NTP reduction(NTPRD)in dielectric barrier discharge reactor(DBD).The effect of O_(2)molar fraction on NO_(x)species in the outlet of DBD,and effects of NH_(3)/NO_(x)molar ratio and discharge power of DBD on NO_(x)removal efficiency are *** indicate that anaerobic condition and higher discharge power is beneficial to direct removal of NO_(x),and the NO_(x),removal efficiency can be up to 98.5%under the optimal operating *** is also found that adding NH_(3)is favorable for the reduction of NO_(x),to N_(2)at lower discharge *** addition,the NO_(x)removal mechanism and energy consumption analysis for the NTPRD process are also *** is found that the reduced active species(N^(+),N^(-),N^(+),N_(2)^(*),NH_(2)^(+),etc.)generated in the NTPRD process play important roles for the reduction of NO_(x),to N_(2).Our work paves a novel pathway for NO_(x)removal from anaerobic gas in industrial application.

关键词： NO_(x)removal NTP reduction mechanism energy consumption

Controllable and high-throughput preparation of microdroplet using an ultra-high speed rotating packed bed

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Chinese Journal of Chemical Engineering 2022年第8期35卷 116-124页

作者： Jing Xie Xiangbi Jia Dan Wang Yingjiao Li Bao-chang Sun Yong Luo guang-wen chu Jian-feng Chen State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

Microdroplets and their dispersion,with a large specific surface area and a short diffusion distance,have been applied in various unit operations and reaction ***,it is still a challenge to control the size and size distribution of microdroplets,especially for high-throughput *** this work,a novel ultra-high speed rotating packed bed(UHS-RPB)was invented,in which rotating foam packing with a speed of 4000-12000 r·min^(-1) provides microfluidic channels to disperse liquid into microdroplets with high *** generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet *** this UHS-RPB,the effects of rotational speed,liquid initial velocity,liquid viscosity,liquid surface tension and packing pore size on the average size(d_(32))and size distribution of microdroplets were systematically *** showed that the UHS-RPB could produce microdroplets with a d_(32) of 25-63μm at a liquid flow rate of 1025 L·h^(-1),and the size distribution of the microdroplets accords well with Rosin-Rammler distribution *** addi-tion,a correlation was established for the prediction of d_(32),and the predicted d_(32) was in good agreement with the experimental data with a deviation within±15%.These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

关键词： Ultra-high speed rotating packed bed Microdroplet Controllable preparation High throughput

Preparation of Pd/c-Al_(2)O_(3)/nickel foam monolithic catalyst and its performance for selective hydrogenation in a rotating packed bed reactor

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Chinese Journal of Chemical Engineering 2022年第1期35卷 311-319页

作者： Hai-Long Liao Bao-Ju Wang Ya-Zhao Liu Yong Luo Jie-Xin Wang guang-wen chu Jian-Feng Chen State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

Selective hydrogenation plays an important role in chemical industries,yet its selectivity is usually limited by the mass *** this work,the enhanced hydrogenation selectivity was achieved in a rotating packed bed(RPB)reactor with excellent mass transfer *** to be used under the centrifugal filed,a monolithic catalyst Pd/c-Al_(2)O_(3)/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition *** mechanical strength of the catalyst can meet the requirement of high centrifugal force in the *** hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3–8 times higher than that in a stirred tank reactor under similar *** work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.

关键词： Monolithic catalyst Rotating packed bed reactor Hydrogenation Selectivity

An Evaluation of Metronidazole Degradation in a Plasma-Assisted Rotating Disk Reactor Coupled with TiO2 in Aqueous Solution

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Engineering 2021年第11期7卷 1603-1610页

作者： Yong Cai guang-wen chu Yong Luo Meng-Jun Su Bao-Ju Wang Bao-Chang Sun Jian-Feng Chen State Key Laboratory of Organic–Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High-Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental *** discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this *** this work,a plasma-assisted rotating disk reactor(plasma-RDR)and a photocatalyst—namely,titanium dioxide(TiO_(2))—were coupled for the treatment of metronidazole(MNZ).Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR,which contributed to the utilization of ultraviolet(UV)light radiation in the presence of TiO_(2).The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41%and 2.954 mg∙L^(-1) as the rotational speed increased from 0 to 500 r∙min^(-1).The synergistic effect of plasma-RDR plus TiO_(2) on the generation of hydroxyl radicals was *** intermediate products were identified using three-dimensional(3D)excitation emission fluorescence matrices(EEFMs)and liquid chromatography-mass spectrometry(LC-MS),and a possible degradation pathway is proposed *** plasma-catalytic process has bright prospects in the field of antibiotics degradation.

关键词： Plasma-assisted rotating disk reactor Pulsed discharge Metronidazole Degradation TiO_(2)

Differentially private SGD with random features

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 1-23页

作者： WANG Yi-guang GUO Zheng-chu Polytechnic Institute of Zhejiang University Zhejiang UniversityHangzhou 310015China School of Mathematical Sciences Zhejiang UniversityHangzhou 310058China

In the realm of large-scale machine learning,it is crucial to explore methods for reducing computational complexity and memory demands while maintaining generalization ***,since the collected data may contain some sensitive information,it is also of great significance to study privacy-preserving machine learning *** paper focuses on the performance of the differentially private stochastic gradient descent(SGD)algorithm based on random *** begin,the algorithm maps the original data into a lowdimensional space,thereby avoiding the traditional kernel method for large-scale data storage ***,the algorithm iteratively optimizes parameters using the stochastic gradient descent ***,the output perturbation mechanism is employed to introduce random noise,ensuring algorithmic *** prove that the proposed algorithm satisfies the differential privacy while achieving fast convergence rates under some mild conditions.

关键词： learning theory differential privacy stochastic gradient descent random features reproducing kernel Hilbert spaces