CFD Simulation of Large Dust Collection Cyclones Positioned Vertically in Staggered Downward Cascade Arrangement

2013 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Cfd Simulation ◽  
Solid Phase ◽  
Phase Particle ◽  
High Mass ◽  
Cfd Modeling ◽  
Cement Kiln ◽  
Dust Collection ◽  
Dry Process ◽  
Cascade Arrangement ◽  
Simulation Results

Three dimensional, time dependent Euler-Euler simulation approach for numerical calculation of multiphase strongly swirling turbulent gas-heavy laden particulate flow in large industrial collection cyclones, positioned vertically, in staggered downward cascade arrangement has been performed. The multiphase flow was featured high mass loading. This paper specifically addresses a CFD modeling of a “suspension preheater”, typical equipment for dry process cement kiln. Big sized cyclone separator is a key component of this device. The simulation case study was developed in the frame of the commercial general-purpose code ANSYS-Fluent R13. In cyclone separators the swirling gas motion induces a centrifugal force on the solid particulate phase which is the driving force behind the separation process. The turbulence disperses the solid particulates and enhances the probability that particles are discharged, as reject. Both phenomena are related to solid phase particle size distribution (PSD) and flow pattern into the collection cyclones. The multiphase turbulence was modeled using the RSM Mixture Turbulence Model. The simulation results were validated against industrial measurements carried out on an industrial suspension preheater, in the frame of heat and mass balance of cement kiln energy audit. The numerical simulation results were found in reasonable agreement with the collected industrial measurements. This CFD simulation represents a powerful engineering tool on behalf of the cement process engineer either for new cutting-edge design or for performance verification of an existing plant.

Validation of CFD Modeling and Simulation of a Simplified Automotive Model

2015 ◽  
Vol 735 ◽  
pp. 319-325
Author(s):  
S. Mansor ◽  
N.A.R. Nik Mohd ◽  
C.W. Chung
Keyword(s):  
Wind Tunnel ◽  
Modeling And Simulation ◽  
Best Practice ◽  
Cfd Simulation ◽  
Wind Tunnel Test ◽  
Turnaround Time ◽  
Cfd Modeling ◽  
Design Changes ◽  
Wind Tunnel Data ◽  
Simulation Results

In the early design phase of automotive sector, the flow field around the vehicle is important in decision making on design changes. It would consume a lot of money and time for multiple prototypes development if adopt traditional testing method which is wind tunnel test. Thus, numerical method such as Computational Fluid Dynamics (CFD) simulation plays an important role here. It is very often simulation results been compared with wind tunnel data. However, with various mesh types, meshing methodology, discretization methods and different solver control options in CFD simulation, users may feel low confidence level with the generated simulation results. Thus, a robust modeling and simulation guideline which would help in accurate prediction should be developed due to the industry’s demand for accuracy when comparing CFD to wind tunnel results within short turnaround time. In this paper, a CFD modeling and simulation study was conducted on a simplified automotive model to validate with wind tunnel test results. The wind tunnel environment was reproduced in the simulation setup to include same boundary conditions. Meshing guidelines, turbulence model comparisons and also the best practice for solver setup with respect to accuracy will be presented. Overall, CFD modeling and simulation methods applied in this paper are able to validate the results from experiment accurately within small yaw ranges.

CFD Modeling of Multi-Fuel Suspension Co-Combustion and Calcination Processes Within a DDF Precalciner of Cement Kiln

2020 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Alternative Fuels ◽  
Radiation Heat Transfer ◽  
Engineering Application ◽  
Raw Material ◽  
Cfd Modeling ◽  
Thermochemical Conversion ◽  
Cement Kiln ◽  
Discrete Phase Model ◽  
Local Flow ◽  
Dry Process

Abstract The paper reports a CFD engineering application for modeling the thermal-fluid dynamics and thermochemical conversion processes, which govern the conventional air-fossil fuel firing or multi-fuel co-processing, responsible for thermal sustain of raw material calcination process, within a dry process cement kiln. We simulate a Dual-Combustion and Denitration Furnace (DDF) precalciner, which co-combusts in suspension the petroleum coke (primary fuel) with alternative fuels (e.g., the pre-dried sewage sludge and/or the animal meat and bonemeal). CFD software package ANSYS Fluent R18.2 is used to build CFD reactive model and to perform the numerical simulations. The Eulerian–Lagrangian approach is usually employed for modeling turbulent multiphase reacting flows. Few turbulence and radiation heat transfer models are compared, to identify pros and cons of each model applicability and to determine which model is most suitable. The Discrete Phase Model (DPM), in Lagrangian framework, is employed for tracking petcoke/alternative fuels and limestone particle clouds. CFD analysis provides valuable insights into the DDF precalciner performance e.g., combustion and calcination characteristics, in-furnace NOx control strategy by combustion aerodynamics optimization (particularly the effect of Tertiary Air tangential inlet, which creates swirl and induces several local flow recirculation zones). The major predicted results e.g., exit degree of calcination, fuel burnout, gas species concentration fields etc., are quite well captured and validated against control system continuously logged operation data and the measurements collected by newly installed instrumentation.

scholarly journals CFD Modeling of Gas–Solid Cyclone Separators at Ambient and Elevated Temperatures

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 228 ◽  
Author(s):  
Mohammadhadi Nakhaei ◽  
Bona Lu ◽  
Yujie Tian ◽  
Wei Wang ◽  
Kim Dam-Johansen ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Cfd Simulation ◽  
Separation Efficiency ◽  
Flow Behavior ◽  
Industrial Applications ◽  
High Mass ◽  
Cfd Modeling ◽  
Solid Flow ◽  
Solids Loading ◽  
Wide Range

Gas–solid cyclone separators are widely utilized in many industrial applications and usually involve complex multi-physics of gas–solid flow and heat transfer. In recent years, there has been a progressive interest in the application of computational fluid dynamics (CFD) to understand the gas–solid flow behavior of cyclones and predict their performance. In this paper, a review of the existing CFD studies of cyclone separators, operating in a wide range of solids loadings and at ambient and elevated temperatures, is presented. In the first part, a brief background on the important performance parameters of cyclones, namely pressure drop and separation efficiency, as well as how they are affected by the solids loading and operating temperature, is described. This is followed by a summary of the existing CFD simulation studies of cyclones at ambient temperature, with an emphasis on the high mass loading of particles, and at elevated temperatures. The capabilities as well as the challenges and limitations of the existing CFD approaches in predicting the performance of cyclones operating in such conditions are evaluated. Finally, an outlook on the prospects of CFD simulation of cyclone separators is provided.

Modeling and Predicting Gas-Solid Fluidized Bed Dynamics to Capture Nonuniform Inlet Conditions

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Santhip K. Kanholy ◽  
Jillian Chodak ◽  
Brian Y. Lattimer ◽  
Francine Battaglia
Keyword(s):  
Binary Mixture ◽  
Fluidized Beds ◽  
Cfd Simulation ◽  
Solid Phase ◽  
Particle Diameter ◽  
Cfd Modeling ◽  
Dead Zones ◽  
Modeling Approach ◽  
Inlet Conditions ◽  
Eulerian Modeling

The hydrodynamics of fluidized beds involving gas-solids interactions are very complex, and modeling such a system using computational fluid dynamics (CFD) modeling is even more challenging for mixtures composed of nonuniform particle characteristics such as diameter or density. Another issue is the presence of dead-zones, regions of particles that do not fluidize and accumulate at the bottom of the bed, affecting uniform fluidization of the material. The dead zones typically form between the gas jets and depend on the spacing of the distributor holes and gas velocity. Conventionally, in Eulerian–Eulerian modeling for gas-solid mixtures, the solid phase is assumed to behave like a fluid, and the presence of dead zones are not typically captured in a CFD simulation. Instead, the entire bed mass present in an experiment is usually modeled in the simulations assuming complete fluidization of the bed mass. A different modeling approach was presented that accounts for only the fluidizing mass by adjusting the initial mass present in the bed using the measured pressure drop and minimum fluidization velocity from the experiments. In order to demonstrate the fidelity of the new modeling approach, three different bed materials were examined that can be classified as Geldart B particles. Glass beads and ceramic beads of the same mean particle diameter were used, as well as larger-sized ceramic particles. Binary mixture models were also validated for two types of bed mixtures consisting of glass-ceramic and ceramic-ceramic compositions. It was found that adjusting the amount of fluidizing mass in the modeling of fluidized beds best predicted the fluidization dynamics of an experiment for both single phase and binary mixture fluidized beds.

A Two-Phase CFD Modeling Approach to Investigate the Flow Characteristics in Radial Flow Moving-Bed Reactors

2014 ◽  
Vol 12 (1) ◽  
pp. 497-512 ◽  
Author(s):  
Fang-Zhi Xiao ◽  
Zheng-Hong Luo
Keyword(s):  
Radial Flow ◽  
Solid Phase ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Cfd Modeling ◽  
Reactor Model ◽  
Two Phase ◽  
Moving Bed ◽  
Porous Media Model ◽  
Simulation Results

Abstract Based on a complete CFD Eulerian–Eulerian two-fluid approach, a comprehensive three-dimensional (3D) two-phase reactor model was suggested to describe the flow behavior in radial flow moving-bed reactors (RFMBRs). A porous media model was incorporated into the reactor model in order to describe the flow resistance provided by the porous walls of the center and annular pipes. Compared with these previous reactor models, the reactor model considers the solid-phase movement instead of immobilization, which benefits for predicting the formation of cavity practically. The simulation results are agreement with the published experimental data. By employing the verified model, the flow field parameters in the reactors such as pressure drop and flow velocity were obtained. Besides, the simulations were then carried out to investigate the effect of the bed voidage on the flow behavior and to understand the phenomenon of cavity in the RFMBRs. The simulation results showed that both the centripetal and the centrifugal flow configurations have the inhomogeneous flow distribution and the phenomenon of cavity. Furthermore, the inhomogeneous distribution increases with the increase of the bed voidage, whereas the phenomenon of cavity is more obvious with the increase of gas inlet velocity. As a whole, this work provided a realistic modeling and a useful approach for the understanding of RFMBRs.

3D CFD Simulation of Gas Hold-up and Mass Transfer in a Modified Airlift Reactor with Net Draft Tube

2019 ◽  
Vol 17 (12) ◽  
Author(s):  
Mehran Nalband ◽  
Elham Jalilnejad
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Cfd Simulation ◽  
Draft Tube ◽  
Axial Flow ◽  
Cfd Modeling ◽  
Reactor Performance ◽  
Simulation Results ◽  
The Impact

Abstract This paper documents CFD simulations of the gas hold-up (ɛg) and volumetric mass transfer coefficient (KLa) for three kinds of airlift reactors (ALRs) namely, conventional ALR, ALR with net draft tube (ALR-ndt), and packed-bed ALR with net draft tube (PBALR-ndt). The 3D two-fluid Eulerian-Eulerian model was adopted to predict the influence of superficial gas velocity on ɛg and KLa. The simulation results were consistent with the trends described previously in the experimental work regarding ɛg and KLa values and a good agreement was obtained (absolute error less than 20 %). Based on the simulation results, axial flow is the dominant flow in the conventional ALR while in ALR-ndt and PBALR-ndt radial flow streamlines are appeared in the reactors due to the presence of concentric net draft tube which improves their performance. The effective role of the net draft tube is proven since consequence of generation of small bubbles by passing through net draft tube is the entrainment of a larger percentage of gas bubbles from the riser into the downcomer which results in improvement of gas holdup and the KLa values. An exponential correlation is used for relating gas hold-up and mass transfer coefficient. Higher power obtained for ALR-ndt and PBALR-ndt (n ≈ 1.22) compared to ALR (n = 0.95) was indicative of high sensitivity of KLa value to gas hold-up in these reactors due to presence of the concentric net draft tube. The CFD modeling is considered to be an invaluable tool allowing us to analyze and visualize the impact of fluidic forces on hydrodynamic properties and consequently, reactor performance.

scholarly journals CFD Simulation of Solid Suspension for a Liquid–Solid Industrial Stirred Reactor

2021 ◽  
Vol 11 (12) ◽  
pp. 5705
Author(s):  
Adrian Stuparu ◽  
Romeo Susan-Resiga ◽  
Alin Bosioc
Keyword(s):  
Chemical Reaction ◽  
Cfd Simulation ◽  
Simulation Analysis ◽  
Solid Phase ◽  
Initial Conditions ◽  
Chemical Reactor ◽  
Liquid Mixtures ◽  
Multiphase Model ◽  
Chemical Product ◽  
Two Phase

The present study examines the possibility of using an industrial stirred chemical reactor, originally employed for liquid–liquid mixtures, for operating with two-phase liquid–solid suspensions. It is critical when obtaining a high-quality chemical product that the solid phase remains suspended in the liquid phase long enough that the chemical reaction takes place. The impeller was designed for the preparation of a chemical product with a prescribed composition. The present study aims at finding, using a numerical simulation analysis, if the performance of the original impeller is suitable for obtaining a new chemical product with a different composition. The Eulerian multiphase model was employed along with the renormalization (RNG) k-ε turbulence model to simulate liquid–solid flow with a free surface in a stirred tank. A sliding-mesh approach was used to model the impeller rotation with the commercial CFD code, FLUENT. The results obtained underline that 25% to 40% of the solid phase is sedimented on the lower part of the reactor, depending on the initial conditions. It results that the impeller does not perform as needed; hence, the suspension time of the solid phase is not long enough for the chemical reaction to be properly completed.

Optimization of Structure and Calculation of Flow-Force on Poppet Valve under Converging Flow

2011 ◽  
Vol 339 ◽  
pp. 148-151 ◽  
Author(s):  
Shu Juan Zheng ◽  
Long Quan
Keyword(s):  
Cfd Simulation ◽  
Internal Flow ◽  
Poppet Valve ◽  
Converging Flow ◽  
Simulation Results

This paper optimizes the structure of the poppet valve based on the internal flow. The flow-force on poppet valve in the case of the converging flow is simulated and studied by CFD. Simulation results represent that the traditional formula for computing the flow-force can be used only in the certain range, so the formula is modified based on the simulation result.

Numerical simulation and field test study of desulfurization wastewater evaporation treatment through flue gas

2014 ◽  
Vol 70 (7) ◽  
pp. 1285-1291 ◽  
Author(s):  
Jia-jia Deng ◽  
Liang-ming Pan ◽  
De-qi Chen ◽  
Yu-quan Dong ◽  
Cheng-mu Wang ◽  
...  
Keyword(s):  
Field Test ◽  
Flue Gas ◽  
Cfd Simulation ◽  
Electrostatic Precipitator ◽  
Negative Impact ◽  
Positive Impact ◽  
Field Tests ◽  
Gas Temperature ◽  
Simulation Results ◽  
Desulfurization Wastewater

Aimed at cost saving and pollution reduction, a novel desulfurization wastewater evaporation treatment system (DWETS) for handling wet flue gas desulfurization (WFGD) wastewater of a coal-fired power plant was studied. The system's advantages include simple process, and less investment and space. The feasibility of this system has been proven and the appropriate position and number of nozzles, the spray droplet size and flue gas temperature limitation have been obtained by computational fluid dynamics (CFD) simulation. The simulation results show that a longer duct, smaller diameter and higher flue gas temperature could help to increase the evaporation rate. The optimal DWETS design of Shangdu plant is 100 μm droplet sprayed by two nozzles located at the long duct when the flue gas temperature is 130 °C. Field tests were carried out based on the simulation results. The effects of running DWETS on the downstream devices have been studied. The results show that DWETS has a positive impact on ash removal efficiency and does not have any negative impact on the electrostatic precipitator (ESP), flue gas heat exchanger and WFGD. The pH values of the slurry of WFGD slightly increase when the DWETS is running. The simulation and field test of the DWETS show that it is a feasible future technology for desulfurization wastewater treatment.

Study of CFD Modeling of Performance for Classification

2012 ◽  
Vol 516-517 ◽  
pp. 784-789
Author(s):  
Wei Cao ◽  
Ying Fang ◽  
De Xiang Li
Keyword(s):  
Simulation Experiment ◽  
Particle Trajectory ◽  
Phase Particle ◽  
Theoretical Perspective ◽  
Cfd Modeling ◽  
Optimized Design ◽  
Two Phase ◽  
Ansys Cfx ◽  
The One ◽  
Classification Efficiency

The numerical simulation in the classification has been used in ANSYS CFX 10.0. We described the different flow fields within the classification in accordance with the one-phase simulation experiment, which provided a new theoretical perspective for optimized design on classification. At the same time, the classification efficiency was predicted by simulation for two phase particle trajectory. This will lay a foundation for improving classification efficiency.

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