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Effect on the Flow Behaviors by Adding Internals in a riser Reactor

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Open Journal of Fluid Dynamics 2017年第1期7卷 72-82页

作者： Liuhai Feng Yifeng Bu Juan Wang Yu Mao Zhuowu Men National Institute of Clean-and-Low Carbon Energy Beijing China College of Chemical Engineering China University of Petroleum Beijing China

riser reactor is a key unit in the Fluid Catalytic Cracking (FCC), and it has important influences on increasing the yield coefficient of gas and oil. In this paper, the behaviors of gas-solid two-phase flow in the traditional y-type riser reactor are investigated by numerical simulation. The calculated particle concentration distribution is in good agreement with the experimental data, which verified the advanced models and calculating methods. The non-uniform distribution, such as core-annulus flow, may result in the unreasonable matching relationship of catalyst-to-oil ratio. An optimized riser with cuneal internals is proposed and the comparison of two different structures of riser reactor is presented. The comparison results show that the cuneal internals in the riser both can block effectively the slip down of the particles near wall region and weaken core-annulus flow structure due to the redistribution of particles. The results also prove that the particle concentration distribution becomes uniform along the axial and radial direction in the optimized riser by adding cuneal internals, which would be benefits for the catalytic cracking reactions.

关键词： riser Reactor Gas-Solid Two-Phase Flow Core-Annulus Flow Structure Numerical Simulation

Mapping Correlation Dimension along the Wall Region of a High-Flux Gas-Solid riser Using Embedded Solid Concentration Time Series

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Engineering（科研） 2018年第10期10卷 655-679页

作者： Justin M. Jeremiah Samwel V. Manyele Abraham K. Temu Jesse-X. Zhu Department of Chemical and Mining Engineering University of Dar es Salaam Dar es Salaam Tanzania Department of Chemical and Biochemical Engineering University of Western Ontario London Canada

Analysis of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux conditions using the established method.

关键词： Correlation Integral Mapping Correlation Dimension High-Flux Gas-Solid riser Embedded Solid Concentration Time Series

Development of Dispersion Models for the Simulation of Fluid Catalytic Cracking of Vacuum Gas Oil in riser Reactor

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Advances in Chemical Engineering and Science 2018年第4期8卷 298-310页

作者： Kenneth Kekpugile Dagde Department of Chemical/Petrochemical Engineering Rivers State University Port Harcourt Nigeria

Dispersion models for the simulation of an industrial Fluid Catalytic Cracking riser Reactor have been developed. The models were developed based on the principle of conservation of mass and energy on the reacting species due to bulk flow and axial dispersion. The four-lump kinetic scheme was used to describe the cracking reactions occurring in the reactor. The model equations were a set of parabolic Ordinary Differential Equations which were reduced to first order differential equations by appropriate substitutions and integrated numerically using 4th order Runge Kutta algorithm using Visual Basic 6.0. Results obtained showed a maximum percentage deviation ranging from 0.31% to 5.7% between model predictions and industrial plant data indicating reasonable agreement. Simulation of model at various operating parameters gave optimum gasoline yield of 45.6% of the most significant variable of temperature (658 K), superficial velocity (0.1 m/s), catalyst to gas oil ratio (7.0) and diffusion coefficient of 0.23 m2/s.

关键词： Modelling and Simulation Axial Dispersion Vacuum Gas Oil riser Reactor Visual Basic 6.0

Mapping the Wall-Region Dynamics of High-Flux Gas-Solid riser Using Scaling Regions from the Solid Concentration Time Series

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Engineering（科研） 2019年第1期11卷 74-92页

An experimental study of the gas-solid flow dynamics in the high-flux CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles of 67 μm mean diameter and 1500 kg/m3 density together with 70% to 80% humid air was used. Solid concentration data were analysed using codes prepared in FORTRAN 2008 to get correlation integrals at different embedding dimensions and operating conditions and plot their profiles. Scaling regions were identified by visual inspection method and their location on planes determined. Scaling regions were analysed based on operating conditions and riser spatial locations. It was found that scaling regions occupy different locations on the plane depending on the number of embedding dimensions and operating conditions. As the number of embedding dimensions increases the spacing between scaling regions decreases until it saturates towards higher embedding dimensions. Slopes of scaling regions increases with embedding dimensions until saturation where they become constant. Slopes of scaling regions towards the wall decrease while the number of scaling regions for a particular profile increases. The span of the scaling region is wider at the initial values of hyperspherical radius than its final values. The scaling regions in some flow development sections show multifractal behaviour for each embedding dimension which manifests into visible basin which is defined in this study as multifractal basin. Further, the end points of the scaling region for each correlation integral profile differ from each other as the embedding dimension changes. This study suggests that identification of scaling region by visual inspection method is useful in understanding the gas-solid flow d

关键词： Scaling Region Correlation Integral Correlation Dimension Embedding Dimensions Multifractal Basin High-Flux riser

Steel Catenary riser Fatigue Life Prediction Using Linearized Hydrodynamic Models

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World Journal of Engineering and Technology 2017年第4期5卷 564-573页

作者： C. Ebunuoha C. V. Ossia Offshore Technology Institute Faculty of Engineering University of Port Harcourt Port Harcourt Nigeria

Steel catenary risers, (SCR) usually installed between seabed wellhead and floating platform are subjected to vortex shedding. These impose direct forces, hence cyclic stresses, and fatigue damage on the SCR. riser failure has both economic and environmental consequences;hence the design life is usually greater than the field life, which is significantly reduced by vortex induced vibration (VIV). In this study, SCR and metOcean data from a field in Offshore Nigeria were substituted into linearized hydrodynamic models for simulations. The results showed that the hang off and touchdown regions were most susceptible to fatigue failure. Further analysis using Miner-Palm green models revealed that the fatigue life reduced from a design value of 20-years to 17.04-years, shortened by 2.96-years due to VIV. Furthermore, a maximum wave load of 5.154 kN was observed. The wave loads results corroborated with those obtained from finite element Orca Flex software, yielding a correlation coefficient of 0.975.

关键词： Fatigue Life Linearized Hydrodynamic Models Steal Catenary riser

Analysis of Flow Dynamics in the High-Flux Gas-Solid riser Using Trajectory Distances across Attractors Reconstructed from Solid Concentration Signals

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Engineering（科研） 2018年第10期10卷 688-703页

The study of the entrance and wall dynamics of a high-flux gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the expansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the expansion of the attractor.

关键词： Trajectory Distance Probability Density Function Cumulative Distribution Function Euclidian Distance High-Flux riser

Nonlinear Static Finite Element Stress Analysis of Pipe-in-Pipe risers

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China Ocean Engineering 2005年第1期19卷 155-166页

作者：周宏杰闫澍旺崔溦 School of Construction Engineering Tianjin University Tianjin 300072 China

Owing to the complexity of the pipe-in-pipe (PIP) riser system in structure, load and restraint, many problems arise in the structural analysis of the system. This paper presents a new method for nonlinear static finite element stress analysis of the PIP riser system. The finite element (FE) model of the PIP riser system is built via software AutoPIPE 6.1. According to the specialties of a variety of components in the PIP riser system, different elements are used so as to model the system accurately. Allowing for the complication in modeling the effects of seabed restraint, a technique based on the bilinear spring concept is developed to calculate the soil properties. Then, based on a pipeline project, the entire procedure of stress analysis is discussed in detail, including creation of an FE model, processing of input data and analysis of results. A wide range of loading schemes is investigated to ascertain that the stresses remain within the acceptable range of the pipe material strength. Finally, the effects of the location of flanges, the thermal expansion of submarine pipelines and the seabed restraint on stress distribution in the riser and expansion loop are studied, which are valuable for pipeline designers.

关键词： pipe-in-pipe stress analysis pipe-soil interaction riser FE

INSIGHT INTO DISTILLATION/ABSORPTION COLUMNS AND FCC riserS USING GAMMA SCANNING TECHNIQUE

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Chinese Journal of Chemical Engineering 1995年第3期3卷 50-58页

作者：鲍晓军何开安刘艳升沈复石油大学（北京）化工系北京 102200 石油大学（北京）化工系北京

This paper presents the application of gamma ray scanning technique to distillation/absorption columns and FCC *** flow regime *** liquid height,froth *** height over the exit weir on a V-1 type valve tray and downcomer hydraulics were investigatedusing the scanning device previously *** solid distribution and coke deposition were experi-mentally simulated in a FCC riser simulator by employing a three dimensional scanning device devel-oped for the present *** success of this investigation should shed a light forquantifying two-phase contact phenomena in various gas liquid and gas solid two phase flow system.

关键词： distillation absorption column. FCC riser gamma ray. hydraulics

Early monitoring of gas infl ux of drilling fl uid in risers during deepwater drilling using Lamb waves

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Applied Geophysics 2019年第1期16卷 25-32页

作者： Duan Wen-Xing Xiao Cheng-Wen Ai Yong Xin Yi Zhu Lei Exploration and Development Research Institute of Petro China Tarim Oilfi eld Company Korla 841000China

Early warning of gas in deepwater drilling risers is critical to the timely detection of seepage and consequently blowout reduction. We numerically simulate the acoustic fi eld in water-based drilling fl uids from a sound source outside the riser by using a 3D cylindrical coordinates finite-difference method. By changing the gas content of the drilling fluid, the relation between the amplitude and attenuation of the A0- and the S0-mode Lamb waves in the riser, the fl uid properties in the pipe, and the position of the top and bottom interfaces of the slug fl ow were assessed. The simulation results suggests that the amplitude and attenuation of the Lamb waves refl ect the gas content in the riser and are sensitive to low gas content. Moreover, the Lamb waves amplitude and attenuation reflect the position of the top and bottom interface of the slug fl ow.

关键词： Deepwater drilling Lamb wave riser gas infl ux monitoring