scholarly journals Studi Fluidisasi dan Pembakaran Batubara Polydisperse di Dalam Fluidized Bed Berbasis Simulasi CFD (Computational Fluid Dynamic)

2018 ◽  
Vol 2 (1) ◽  
pp. 40
Author(s):  
Mochammad Agung Indra Iswara ◽  
Tantular Nurtono ◽  
Sugeng Winardi
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Mass Fraction ◽  
Cfd Simulation ◽  
Solid Phase ◽  
Fluid Dynamic ◽  
Data Retrieval ◽  
Pulverized Coal ◽  
Solid Mass ◽  
Time Step

Penelitian ini bertujuan untuk mengetahui fenomena pembakaran batubara dimana dimensi alat, distribusi ukuran partikel, dan jenis kualitas batubara menggunakan validasi dari penelitian Wang. Penelitian ini mengarahkan pada simulasi berbasis CFD. Kondisi operasi pada saat simulasi pembakaran dilakukan pada kecepatan bubbling. Metode yang digunakan sebelum melakukan simulasi pembakaran merupakan kelanjutan dari simulasi fluidisasi dimana masih menggunakan geometri 2-D fluidized bed lalu dilakukan meshing, selanjutnya memasukkan persamaan energi. Geometri fluidized bed yang digunakan berbentuk tabung dengan panjang silinder fluidized bed 1370 mm, diameter silinder 152 mm. Bahan yang digunakan pada penelitian ini berupa pulverized coal dengan jenis batubara Bituminous dimana ukuran partikel dianggap polydisperse dengan ukuran partikel 1 mm dan 1,86mm yang masing-masing sebesar 50% fraksi massa dengan kecepatan 0,2 Kg/s dan suhu 1200 K, dan udara luar yang diinjeksikan dengan kecepatan 0,8 m/s dan suhu 300 K. Analisa pengambilan data adalah berupa kontur fase padatan, kontur temperatur pada fase-1 dan fase padatan, fraksi massa produk pembakaran, massa padatan awal dan akhir simulasi dengan time step sebesar 0,0001 detik dan number of time step sebesar 300000. Selanjutnya data tersebut diplot menjadi grafik temperatur terhadap time step dan disajikan dalam setiap 1 menit simulasi selama 5 menit simulasi.This research aims to determine coal combustion’s phenomenon, where the device’s dimension, particle size distribution, and the quality of rank coal  which validated Wang’s reseach. This reseach leads on CFD simulation. The operation condition has did in bubbling velocity. This method is a continuation from fluidization simulation which is use 2-D Geometry and then used the meshing method, and enter the energy equation. The geometry of fluidized bed used was tubular cylinder with 1370 mm length and 152 mm. Materials used in this study was pulverized coal with Bituminous coal type which the particle size was considered as monodispers with particle size was 1.43 mm and polydispersed with particle size was 1 mm with 50% mass fraction and 1.86 mm with 50% mass fraction with flow rate 0,2 Kg/s and the temperature is 1200 K, and the outside air are injected in 0,8 m/s and 300 K. The analysis of data retrieval is solid phase contour, temperature contours in phase-1 and solid phase, mass fraction of combustion product, initial solid mass and final solid mass simulation with time step 0,0001 s and the numberof time step 300000. Then the data is plotted into a graph temperature vs time step and presented in 1 minute simulation for 5 minute simulation.

Effect of Sand Containing Conditions on Wear of Nano Ceramic Coating on Downhole Cyclone

2018 ◽  
Vol 13 (10) ◽  
pp. 1514-1521
Author(s):  
Yong Zhang ◽  
Cunxiao Yin ◽  
Lei Xing ◽  
Wei Liu ◽  
Zhihong Cao
Keyword(s):  
Particle Size ◽  
Wear Rate ◽  
Mass Fraction ◽  
Ceramic Coating ◽  
Fluid Dynamic ◽  
Wear Properties ◽  
Spiral Flow ◽  
Water Separator ◽  
Discrete Phase ◽  
Oil Water

Based on the discrete phase mode (DPM) in Computational Fluid Dynamic (CFD) software Fluent, the numerical simulation and experimental study on erosion wear properties of a new nano ceramic coating for downhole cyclone were carried out under sand containing conditions of the produced liquid. The results showed that the maximum wear position of nano ceramic coating in the spiral flow channel in downhole oil-water separator was in the range of azimuth 108°∼144°, and the coating wear rate increased with the increase of inlet flow velocity. When the particle size of sand phase was less than 0.3 mm, the wear rate of nano ceramic coating on cyclone was greatly affected by the particle size. The wear rate decreased with the increase of particle size. When the particle size of sand phase was larger than 0.3 mm, the wear rate of nano ceramic coating was less affected by the particle size. At the same time, the sand phase mass fraction was in the range of 0.1%∼3%. With the increase of sand content in the produced liquid, the wear rate of the cyclone coating increased gradually.

CFD Simulation of Different Flow Regimes of the Spout Fluidized Bed with Draft Plates

2017 ◽  
Vol 899 ◽  
pp. 89-94
Author(s):  
Bruna Sene Alves Araújo ◽  
Kássia Graciele dos Santos
Keyword(s):  
Fluid Dynamics ◽  
Fluidized Bed ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Scale Up ◽  
Flow Regimes ◽  
Chemical Transformations ◽  
Experimental Fluid Dynamics ◽  
Computation Fluid Dynamics ◽  
Two Phases

Spout fluidized bed has shown promising for gas-solid contact operations with and without chemical reactions, such as drying, coating, granulation, gasification, pyrolysis, etc. This is because these beds combine features from both spouted and fluidized beds. The other point is the ability to treat chemical transformations involving both heat and mass transfer in combination with particles of various sizes. Therefore, it is extremely important the knowledge of fluid dynamic of the bed, mainly for scale-up projects, which makes computer simulation an essential tool. Researches using the Computation Fluid Dynamics (CFD) proved to be very effective in predicting of particles dynamic in this type of bed. In Computation Fluid Dynamics, the two phases are treated as interpenetration continuous, and these phases are described by equations of conservation of mass, momentum and energy. The goal of the present work was to simulate using CFD experimental fluid dynamics data of a spout fluidized bed. Eight distinct flow regimes were identified which showed up in good agreement with the regime map presented in literature. The results showed that the technique was efficient for the simulation of the hydrodynamic of the bed presented.

scholarly journals CFD simulation of solids suspension in stirred tanks: Review

2010 ◽  
Vol 64 (5) ◽  
pp. 365-374 ◽  
Author(s):  
Aoyi Ochieng ◽  
Mrice Onyango
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Concentration Distribution ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Cfd Modeling ◽  
Small Scale ◽  
Stirred Tanks ◽  
Solids Concentration

Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD) techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.

CFD Simulation Research on Flow Characteristics of Fluidized Beds

2014 ◽  
Vol 881-883 ◽  
pp. 1809-1813
Author(s):  
Li Ning Han ◽  
Lu Min Wang
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Particle Distribution ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Flow Characteristics ◽  
Fluidization Velocity ◽  
Motion Characteristics

The Euler-Euler two-fluid model incorporating the kinetic theory of granular flow was applied to simulate the gas-solid flow in fluidized beds. The pressure drop, particle distribution and motion characteristics were studied in this paper. In order to investigate the effect of structure of the fluidized bed on flow characteristics, fluidized beds with different diameters and structures were applied. User defined functions (UDF) were applied to study the flow characteristics when the particle size and mass changed over time. The results showed that with the increase of particle size, higher minimum fluidization velocity was required, but lower pressure drop was obtained. For a certain fluidizing medium, the bed critical fluidization velocity depended only on the size and nature of the particles. The structure of a fluidized bed had an influence on the particle distribution and motion characteristics.

scholarly journals COMPUTATIONAL AND EXPERIMENTAL STUDY OF GRANULATION IN FLUIDIZED BED REACTOR

2019 ◽  
Vol 62 (5) ◽  
pp. 97-103
Author(s):  
Vadim E. Mizonov ◽  
Andrey V. Mitrofanov ◽  
Katia Tannous ◽  
Lev N. Ovchinnikov
Keyword(s):  
Experimental Study ◽  
Particle Size ◽  
Fluidized Bed ◽  
Transition Probabilities ◽  
Cell Model ◽  
Size Fraction ◽  
Fluidized Bed Reactor ◽  
The State ◽  
Time Step ◽  
A Cell

The objective of the study is to build a simple but informative model to describe the kinetics of layering granulation in a batch fluidized bed reactor. A cell model based on the theory of Markov chains to describe this kinetics is proposed. Several parallel chains of perfectly mixed cell according to the number of size fractions, which are under observation, were introduced. The vectors of particles volume content in the cells describe the state of the process. Evolution of the state is conditioned by particles transition from the cells of one chain to another due to their size enlargement during granulation and by particles migration along the chains due to their interaction with fluidizing gas upstream flow. The process is observed in a discrete moments of time. It is supposed that the volume of binding solution coming into a cell of a chain during one time step interacts only with the particles that can enlarge their size to transit to the cell of the next larger size fraction. The migration of the particles of a size fraction along its chain is controlled by the matrix of transition probabilities, which is different for each size fraction and depends on the total particles concentration. The model allows qualitative estimating of influence of the process parameters on the granulation kinetics. In order to validate the model, the experimental study of ammonium sulphate granulation in the lab scale fluidized bed reactor was carried out. The comparison of theoretical and experimental results was done for the example of particle size enlargement at different flow rate of the binding solution feed. A good correlation between theoretical and experimental data was found for both the mean particle size growth and the fraction size distribution at different moments of time.

Dry beneficiation of +0.5mm-5.6mm South African coal using an air dense medium fluidization bed

2021 ◽  
Author(s):  
Elmarie Sunette Diedericks ◽  
Marco Le Roux ◽  
Quentin Peter Campbell
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Separation Efficiency ◽  
Solid Phase ◽  
Poor Performance ◽  
Operating Conditions ◽  
High Mass ◽  
Dense Medium ◽  
Separation Performance ◽  
Coal Particles

Abstract The separation performance of solid phase bed material, at various particle size ranges, in an air dense medium fluidized bed (ADMFB), were evaluated during this study. The coal particles were separated into +0.5mm-1mm, +1mm-2mm, +2mm-2.8mm, +2.8mm-4mm, +4mm-4.75mm and +4.75mm-5.6mm particle size ranges and fed to the fluidized bed in these fractions. Along with the six coal particle size ranges, three dense media to coal ratios and the addition of vibration was tested to identify the best operating conditions. Adequate results were obtained for larger particle size ranges down to and including +2.0mm-2.8mm coal particles, after which the separation performance decreased significantly. Density stratification was irregular and not obvious for coal particles below 2.0mm and maintaining a consistent fluidization state also proved to be challenging, especially when dense medium was added. The coal particles separated vertically along the bed height because of differences in particle and bed density, while particle size proved to have a notable influence on the degree of separation. An air fluidization velocity of between 1.1 to 1.4Umf was shown as the best performing velocity, which yielded the maximum ash differential between the top and bottom layers of the bed for all the particle size ranges tested. For +2.0mm-5.6mm coal particles, low cumulative ash yields were obtained at high mass yields, however the ash yields increased for -2mm coal. Vibration and dense medium have, in some cases, enhanced the separation efficiency of the ADMFB. The -2.0mm particles experienced stronger particle-particle interactions as well as elevated levels of bubbling and back mixing than that of the +2.0mm particles, which explains the poor performance of the small particle sizes.

Effect of Particle Size on Magnitude and Location of Maximum Erosion in S-Bend

2014 ◽  
Author(s):  
Quamrul H. Mazumder
Keyword(s):  
Particle Size ◽  
Oil And Gas ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Fluid Dynamic ◽  
Erosive Wear ◽  
Impact Angle ◽  
Solid Particles ◽  
Particle Sizes ◽  
Fluid Properties

Solid particle erosion is a micromechanical process that is influenced by flow geometry, material of the impacting surface, impact angle, particle size and shape, particle velocity, flow condition and fluid properties. Among the various factors, particle size and velocity have been considered to be the most important parameters that cause erosion. Particle size and velocity are influenced by surrounding flow velocities and carrying fluid properties. Higher erosion rates have been observed in gas-solid flow in geometries where the flow direction changes rapidly, such as elbows, tees, valves, etc., due to local turbulence and unsteady flow behaviors. S-bend geometry is widely used in different fluid handling applications such as automotive, oil and gas, arteries and blood vessels. This paper presents the results of a Computational Fluid Dynamic (CFD) simulation of diluted gas-solid and liquid-solid flows through an S-Bend and the dynamic behavior of entrained solid particles in the flow. CFD analyses were performed at five different particle sizes ranging between 50 and 300 microns. Maximum erosive wear was observed at smaller particle sizes and compared to the larger sizes. The location of maximum erosion was at different locations in the first bend as compared to the second bend.

scholarly journals Limestone particle attrition and size distribution in a bench scale bubbling fluidized bed

2015 ◽  
Vol 17 (2) ◽  
pp. 236-247
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Mass Fraction ◽  
Size Reduction ◽  
Particle Size Reduction ◽  
Bubbling Fluidized Bed ◽  
Cumulative Mass ◽  
Particle Attrition ◽  
Limestone Fines

<div> <p>Attrition of limestone particles in bubbling fluidized bed has significant influence on cyclic CO<sub>2</sub> capture ability of sorbents. The limestone particle attrition and size distribution characteristics were investigated experimentally in a bench scale fluidized bed. The effects of initial particle sizes, fluidized velocity, attrition time and temperature on limestone attrition characteristics were studied. An empirical fitting correlation was proposed to describe the relationship of cumulative mass fraction of limestone fines (<em>R</em>) and attrition time (<em>t</em>). The results show that the fines generation rate decreases and particle size reduction rate increases with increasing initial size. Chipping of large particle takes predominant position when fluidized velocity exceeds the minimum fluidization velocity resulting in more prominent reduction of particle size. After 4 hours attrition, particle size reduction and fines generation rate become constant. It is suggested that cumulative mass fraction of limestone fines (<em>R</em>) increases with attrition time with a function of decaying exponential correlation.</p> </div> <p>&nbsp;</p>

Sesame and Broad Bean Stalks: Mixing Characteristics of Chips as a Biomass Fuel for Bubbling Fluidized Bed Combustor

2018 ◽  
Vol 16 (6) ◽  
Author(s):  
Saad A. El-Sayed ◽  
Amro A. El-baz ◽  
Emad H. Noseir
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Mass Fraction ◽  
Broad Bean ◽  
Sand Particle ◽  
Gas Velocity ◽  
Mixing Index ◽  
Bubbling Fluidized Bed ◽  
Superficial Gas Velocity ◽  
Fluidized Bed Combustor

Abstract Mixing and segregation characteristics of biomass particles are of practical importance because the in-bed combustion efficiency of volatile matter affects the vertical location of biomass in bubbling fluidized bed combustor. Sesame and broad bean stalk biomass materials mixed with sand used in this study. The superficial gas velocity, biomass chip length, sand particle size and mass fraction of biomass varied as experimental variables. The mixing and segregation behavior of mixtures were analyzed in terms of mixing index. It was found that the variability in the chip-shape made the sesame chips is quantitatively and qualitatively higher homogeneity and mixedness than the broad bean chips. The optimum overall mixing index for the sesame and the broad bean is around 0.96 and 0.84 at dimensionless superficial gas velocity (U/Umf) of 2.0 (1.40 m/sec) and 2.1 (1.25 m/sec), respectively. It was found that as the mean diameter increased and the sphericity decreased, the mixing quality decreased. The average sand particle size of 371 µm can keep good mixing with biomass chips of both materials, compared with average particle sizes of sand 550 and 700 µm. Increasing the initial biomass mass fraction yields a poor mixing of the investigated biomass stalks.

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