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Investigation on gas-solids hydrodynamics and matching enhancement in feedstock injection zone of double-level nozzle riser

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Particuology 2023年第4期75卷 165-176页

作者： Xiuying Yao Jun Xu Yiping Fan chunxi lu Fuwei Sun State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China China Kunlun Contracting&Engineering Co LtdBeijing100037China

With the development of current energy economy,it is necessary to improve the product distribution of fluid catalytic cracking process,which is achieved by a riser reactor with double-level of nozzles.The new riser is constructed by adding a level of secondary nozzle 0.5 m below the main nozzle of traditional riser.This paper investigates the gas-solids flow and oil-catalyst matching feature based on the optical fiber and tracer technologies.According to the distribution of solids holdup,particle velocity and dimen-sionless jet concentration,the feedstock injection zone can be divided into the upstream flow control region,the main flow control region,and the secondary flow control region in the radial direction.The size of the regions is changed by the jet gas velocity and axial height.There is a poor match of secondary nozzle jet to particles below the main nozzle.The jet gas from secondary nozzles can improve the matching effect of oil-catalyst near the wall and reduce the probability of coking above the main nozzle.

关键词： Gas-solids flow Matching Feed injection zone Double-level nozzles Riser

Characteristics of flow and liquid distribution in a gas-liquid vortex separator with multi spiral arms

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Particuology 2022年第9期20卷 101-113页

作者： Xiuying Yao Peng Zuo chunxi lu Chenglin E Mengxi Liu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China Research Institute of Experimental and Detection Xinjiang Oilfield CompanyPetroChinaKaramayXinjiang 834000China

Fischer-Tropsch(F-T)synthesis is an important route to achieve the clean fuel production.The perfor-mance of gas-liquid separation equipment involving in the progressive condensation and separation of light and heavy hydrocarbons in the oil-gas products has become a bottleneck restricting the smooth operation of the F-T process.In order to remove the bottleneck,a gas-liquid vortex separator with simple structure,low pressure drop and big separation capacity was designed to achieve the efficient separation between gas and droplets for a long period.The RSM(Reynolds Stress Model)and DPM(Discrete Phase Method)are employed to simulate the flow characteristics and liquid distribution in the separator.The results show that the separation efficiency is influenced by the flow field and liquid phase concentration in the annular zone.The transverse vortex at the top of spiral arm entrains the droplets with small diam-eter into the upper annular zone.The entrained droplets rotate upward at an angle of about 37.4°.The screw pitch between neighbor liquid threads is about 0.3 m.There is a top liquid ring in the top of annular zone,where the higher is the liquid phase concentration,the lower is the separation efficiency.It is found that by changing the operating condition and the annular zone height the vortex can be strengthened but not enlarged by the inlet velocity.The screw pitch is not affected by both inlet velocity and annular zone height.The liquid phase concentration in the top liquid ring decreases with both the increases of inlet velocity and annular zone height.The total pressure drop is almost not affected by the annular zone height but is obviously affected by the inlet velocity.When the height of annular zone is more than 940 mm,the separation efficiency is not changed.Therefore,the annular zone height of 940 mm is thought to be the most economical design.

关键词： Gas-liquid separator Vortex separation Structural optimization Separation performance Computational fluid dynamics

Experimental study on filtration performance of the moving bed granular filter with axial flow

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Particuology 2023年第1期72卷 17-28页

作者： Han Lv Yuxue Liu Yingying Dong Yiping Fan chunxi lu State Key Laboratory of Heavy Oil Processing Department of Chemical Engineering and EnvironmentChina University of PetroleumChangpingBeijing 102249China

The filtration performance of the moving bed granular filter with axial flow (MBGF-AF) is investigated through a large cold experiment. The effect of different operation parameters on the filtration performance (collection efficiency, pressure drop) of the axial-flow moving bed filter is investigated in combination with the dust deposition effect and the mechanism of trapping dust by the capturing particles. The results show that the collection efficiency of MBGF-AF is enhanced by decreasing the superficial gas velocity, increasing the inlet dust concentration properly, or decreasing the moving velocity of the capturing particles. A model covering the above operation parameters is established to calculate the collection efficiency of the moving bed granular filter. It is used in a wide range of operating parameters for the MBGFs.

关键词： Moving bed Granular filter Specific deposit Pressure drop Collection efficiency model

Modeling of pyridine synthesis process in a coupled fluidized bed reactor

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Particuology 2023年第4期75卷 69-81页

作者： Shuaishuai Zhou Jing Li Congzhen Qiao Mengxi Liu chunxi lu Yan Bai College of Chemistry and Chemical Engineering Henan UniversityKaifeng475000China Nanomaterial Engineering Research Center Henan University.Kaifeng475000China Department of State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China

To obtain the optimal operating conditions of a coupled reactor for pyridine synthesis,reactor modeling process is carried out in this paper.During the modeling process,the flow hydrodynamics,heat transfer behavior,inter-phase mass transfer behavior and reaction kinetics were taken into consideration consequently.Further,a regression program based on least square method was proposed to regress the model parameters.The prediction results agreed well with the experimental results with an average deviation of 5.9%.Finally,by setting suitable aim function,the optimal operating conditions of the coupled reactor for pyridine synthesis were determined.

关键词： Reactor modeling Pyridine synthesis Inter-phase mass transfer Optimal operating conditions

Computational fluid dynamics-discrete element method simulation of stirred tank reactor for graphene production

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Chinese Journal of Chemical Engineering 2023年第12期64卷 196-207页

作者： Shuaishuai Zhou Jing Li Kaixiang Pang chunxi lu Feng Zhu Congzhen Qiao Yajie Tian Jingwei Zhang College of Chemistry and Molecular Sciences Henan UniversityKaifeng 475004China National&Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials Henan UniversityKaifeng 475004China Department of State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China Zhejiang luoxing Chemical Co. LtdJiaxing 314001China

Liquid phase exfoliation(LPE)process for graphene production is usually carried out in stirred tank reactor and the interactions between the solvent and the graphite particles are important as to improve the production efficiency.In this paper,these interactions were revealed by computational fluid dynamics–discrete element method(CFD-DEM)method.Based on simulation results,both liquid phase flow hydrodynamics and particle motion behavior have been analyzed,which gave the general information of the multiphase flow behavior inside the stirred tank reactor as to graphene production.By calculating the threshold at the beginning of graphite exfoliation process,the shear force from the slip velocity was determined as the active force.These results can support the optimization of the graphene production process.

关键词： Computational fluid dynamics Discrete element method Stirred tank LPE process Liquid-particle interactions

Flow hydrodynamics in a gas–solid fluidized bed reactor with two reaction zones

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Particuology 2019年第6期17卷 22-32页

作者： Shuaishuai Zhou chunxi lu Mengxi Liu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China

A novel reactor with two reaction zones is proposed for pyridine synthesis.The flow hydrodynamics were investigated in experiments.Pressure taps and a PV-6D optical fiber were used to measure the pressure fluctuation and particle concentration,respectively.Hilbert–Huang analysis was adopted to distinguish the flow patterns through pressure fluctuation.Results show that the flow patterns are bubbling fluidization and fast fluidization in the regions below(reaction zone I)and above(reaction zone II)the nozzles,respectively.The radial distribution of the cluster time fraction was obtained through signal waves of the particle concentration.Analysis of the cluster time fraction revealed two radial distributions.In the region around the nozzles,the cluster time fraction ranged from 0 to 0.2 and concentrated at radial positions r/R=0–1,which resulted from unsymmetrical catalyst feeding.In reaction zone II,the cluster time fraction ranged from 0 to 0.2,and the radial distribution indicated a core–annulus structure.

关键词： Two reaction zones Hilbert–Huang analysis Flow pattern Cluster time fraction

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二元系简单蒸馏与平衡蒸馏的关系

化工学报 2024年第5期75卷 1912-1919页

作者：刘逸群王超卢春喜中国石油集团石油化工研究院有限公司北京102206 中国石油大学(北京)化学工程与环境学院重质油全国重点实验室北京102249 中国石油天然气股份有限公司石油化工研究院北京102206

Rayleigh方程是描述与时间相关的简单蒸馏的基础方程,广泛应用于同位素分馏等多个学科领域,但在化工分离的领域却鲜见报道。针对上述问题,基于组分净摩尔量建立了简单蒸馏的Rayleigh方程和平衡蒸馏的数学模型,并利用数学积分和差分关系,... 详细信息

Rayleigh方程是描述与时间相关的简单蒸馏的基础方程,广泛应用于同位素分馏等多个学科领域,但在化工分离的领域却鲜见报道。针对上述问题,基于组分净摩尔量建立了简单蒸馏的Rayleigh方程和平衡蒸馏的数学模型,并利用数学积分和差分关系,以N级串联平衡蒸馏建立了描述简单蒸馏的计算模型,从而揭示了简单蒸馏与平衡蒸馏间的理论关系。最后利用N级串联平衡蒸馏的数学模型,在N趋于无穷条件下推导出Rayleigh方程。结果表明:Rayleigh蒸馏是简单蒸馏的一种特殊操作工况,其特征为汽化率和加热速率趋于无穷小,蒸馏所需时间无限长。因此,Rayleigh蒸馏更适用于同位素分馏过程。

关键词： Rayleigh方程蒸馏简单蒸馏平衡蒸馏同位素分馏

Influence of the pressure drop and the air lock on the solid flux in a cross-flow moving bed

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Particuology 2021年第2期19卷 166-178页

作者： Ruojin Wang Dewu Wang Yiping Fan chunxi lu School of Chemical Engineering and Technology Hebei University of TechnologyTianjin 300130China College of Chemical Engineering State Key Laboratory of Heavy Oil ProcessingChina University of PetroleumBeijing 102249China

The gas-solid flow pattern in a rectangular cross-flow moving bed is simulated by the multiphase particle-in-cell(MP-PIC)model with the Barracuda software.The computed results are verified by the experimental data.In the bed,the actual solid flux generally equals the solid flow rates in the solid feed and discharge tubes.However,these two flow rates are greatly influenced by the air lock and the pressure drop in the solid feed and discharge tubes,namely,the negative and positive pressure gradients,respectively,rather than the traditional opinion that they are merely controlled by the valve openings.The pressure drops in these tubes are calculated by the proposed“common pressure pool with multiple outlets”(CPPMO)and the“common pressure pool”(CPP)methods.It is found that the local gas resistance dominates the pressure drop in the solid discharge tubes,while the gas frictional resistance determines the pressure drop in the solid feed tube.In addition,when the solid flow rate nearly tends to zero in the solid feed tube,the air lock forms.A solid flux equation is then given by considering both the air lock and the pressure drop factors in the cross-flow moving bed.

关键词： Cross-flow moving bed Barracuda Solid flux Pressure drop Air lock

Heat transfer characterization and improvement in an external catalyst cooler fluidized bed

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Particuology 2021年第3期19卷 103-112页

作者： Jiantao Li Xiuying Yao lu Liu Xudong Zhong chunxi lu State Key Laboratory of Heavy Oil China University of Petroleum(Beijing)Beijing 102249China luoyang R&D Center of Technology SINOPEC Engineering(Group)Co.Ltd.Luoyang 471003China

Gas-solid fluidized beds have been widely used in heat transfer processes,and so there have been many studies focused on increasing heat transfer in such units.In the present work,a pilot scale cold mode experimental rig was constructed to assess the effects of hydrodynamics on bed-to-wall heat transfer and to investigate various means of enhancing heat transfer in a dense gas-solid fluidized bed with external solid circulation.The experimental results show that heat transfer in the dense region played a dominant role in total bed-to-wall heat transfer,accounting for more than 88%of the total heat transfer load.Heat transfer could be lowered as a result of solids bypass that occurred because of external solids circulation,but this effect was weakened by the radial mixing of particles.The heat transfer characteristics identified in this study indicate that a specially designed baffle can be used to enhance bed-to-wall heat transfer.After installing such baffles in the fluidized bed test structure,a 70%increase in the total heat transfer coefficient was obtained.

关键词： Gas-solid fluidized bed Heat transfer Hydrodynamics Baffles Intensification