scholarly journals Modeling and Optimization of Gas-Solid Fluidization of Binary Mixtures using Box-Behnken Experimental Design

2021 ◽  
pp. 16-23
Author(s):  
Abd Ali K.M ◽  
Ghanim A.N
Keyword(s):  
Pressure Drop ◽  
Red Mud ◽  
Hydrodynamic Characteristics ◽  
Gas Velocity ◽  
Minimum Fluidization Velocity ◽  
Bed Height ◽  
Minimum Number ◽  
Experimental Values ◽  
Static Head ◽  
Superficial Gas Velocity

The influence of different factors on the fluidization of a binary mixture of red mud and aluminum was investigated. A new model was developed for predicting pressure drop through the solid bed using experimental data of other work. Statistical analysis based on response surface methodology has been used to develop correlations for bed pressure drop with three independent factors, minimum fluidization velocity (Umf), red mud to aluminum ratio (R/A), and static head (Hs). The design of experiments offers a best alternative to study the effect of factors and their response with the minimum number of experiments. The hydrodynamic characteristics of fluidization, bed pressure drop, superficial gas velocity (Umf), red mud to aluminum ratio (R/A), and initial static bed height (Hs) were modeled and optimized. ANOVA has been used to analyze the system parameters on bed pressure drop. A model of bed pressure drop was found to have a correlation coefficient of 0.98. The measured values of bed pressure drop from RSM were found to match the experimental values very well.

Minimum Fluidization Velocity of Fine Particles

2008 ◽  
Vol 591-593 ◽  
pp. 335-340 ◽  
Author(s):  
Cássia Regina Cardoso ◽  
Carlos Henrique Ataíde ◽  
J.M. Abreu
Keyword(s):  
Pressure Drop ◽  
Fine Particles ◽  
Zinc Powder ◽  
Gas Velocity ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Glass Spheres ◽  
Minimum Fluidization ◽  
Industrial Unit ◽  
Superficial Gas Velocity

The minimum fluidization velocity is an important parameter in the design and operation of an industrial unit of fluidization. In the present work the minimum fluidization velocities of fine particles were obtained through two experimental methodologies. The first one is the classic procedure to determine that parameter analyzing the diagram of medium pressure drop in the bed in function of the superficial gas velocity, during the defluidization of the bed. And the second is the technique of identifying the minimum fluidization velocity interpreting the behavior of the normalized standard deviation of the pressure drop in the bed. A cylindrical bed of transparent acrylic was used in the process and the used particles were glass spheres, FCC and zinc powder. To compare the precision of the two methodologies some equations that predict the minimum fluidization velocity were used.

CFD-DEM Numerical Simulation and Experimental Validation of Heat Transfer and Two-Component Flow in Fluidized Bed

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
Feihong Guo ◽  
Zhaoping Zhong
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluidized Bed ◽  
Quartz Sand ◽  
Thermal Imager ◽  
Gas Velocity ◽  
Bed Height ◽  
Two Component ◽  
Superficial Gas Velocity ◽  
Infrared Thermal Imager

AbstractBased on the improved computational fluid dynamics and discrete element method (CFD-DEM), heat transfer and two-component flow of biomass and quartz sand have been studied from experiments and numerical simulation in this paper. During experiments, the particle temperature and moving images are respectively recorded by infrared thermal imager and high speed camera. With the increase of the velocity, the mixing index (MI) and the cooling rate of the particles are rising. Due to larger heat capacity and mass, the temperature of biomass drops slower than that of quartz sand. Fictitious element method is employed to solve the incompatibility of the traditional CFD-DEM where the cylindrical biomass are considered as an aggregation of numerous fictitious sphere particles arranged in certain sequence. By the comparison of data collected by infrared thermal imager and the simulated results, it can be concluded that experimental data is basically agreement with numerical simulation results. Directly affected by inflow air (25℃), the average temperature of particles in the bed height area (h>30 mm) is about 3 degrees lower than that of the other heights. When the superficial gas velocity is larger, the fluidization is good, and the gas temperature distribution is more uniform in the whole area. On the contrary, bubbles are not easy to produce and the fluidization is restricted at lower superficial gas velocity. Gas-solid heat transfer mainly exists under the bed height of 10 mm, and decreases rapidly on fluidized bed height. The mixing index (MI) is employed to quantitatively discuss the mixing effectiveness, which first rises accelerate, then rising speed decreases, finally tends to a upper limit.

scholarly journals Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

Effect of Drag-Reducing Agent on Slug Characteristics in Multiphase Flow in Inclined Pipes

1999 ◽  
Vol 121 (2) ◽  
pp. 86-90 ◽  
Author(s):  
C. Kang ◽  
W. P. Jepson ◽  
M. Gopal
Keyword(s):  
Pressure Drop ◽  
Multiphase Flow ◽  
Liquid Film ◽  
Froude Number ◽  
Liquid Velocity ◽  
Translational Velocity ◽  
Gas Velocity ◽  
Superficial Gas Velocity ◽  
Inclined Pipes ◽  
Superficial Liquid Velocity

The effect of drag-reducing agent (DRA) on multiphase flow in upward and downward inclined pipes has been studied. The effect of DRA on pressure drop and slug characteristics such as slug translational velocity, the height of the liquid film, slug frequency, and Froude number have been determined. Experiments were performed in 10-cm i.d., 18-m long plexiglass pipes at inclinations of 2 and 15 deg for 50 percent oil-50 percent water-gas. The DRA effect was examined for concentrations ranging from 0 to 50 ppm. Studies were done for superficial liquid velocities between 0.5 and 3 m/s and superficial gas velocities between 2 and 10 m/s. The results indicate that the DRA was effective in reducing the pressure drop for both upflow and downflow in inclined pipes. Pressure gradient reduction of up to 92 percent for stratified flow with a concentration of 50 ppm DRA was achieved in ±2 deg downward inclined flow. The effectiveness of DRA for slug flow was 67 percent at a superficial liquid velocity of 0.5 m/s and superficial gas velocity of 2 m/s in 15 deg upward inclined pipes. Slug translational velocity does not change with DRA concentrations. The slug frequency decreases from 68 to 54 slugs/min at superficial liquid velocity of 1 m/s and superficial gas velocity of 4 m/s in 15 deg upward inclined pipes as the concentration of 50 ppm was added. The height of the liquid film decreased with the addition of DRA, which leads to an increase in Froude number.

Flow Behaviors in a High-Flux Circulating Fluidized Bed

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Xiaofang Wang ◽  
Baosheng Jin ◽  
Wenqi Zhong ◽  
Mingyao Zhang ◽  
Yaji Huang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Mass Flux ◽  
Total Pressure ◽  
Slip Velocity ◽  
Circulating Fluidized Bed ◽  
High Flux ◽  
Flow Ratio ◽  
Gas Velocity ◽  
Solids Holdup ◽  
Superficial Gas Velocity

A high-flux circulating fluidized bed coal gasifier cold model which consists of a vertical riser (0.06m-I.D.×5m-high), two downcomers (0.04m-I.D.×3.5m-high and 0.1m-I.D.×3m-high), an inertial separator, a cyclone and two solid feeding devices were established. Geldart group B particles with mean diameters of 140 ?m and densities of 2700 kg/m3 were used as bed materials. Flow behaviors were investigated with the solid mass flux ranges from 108 to 395 kg/m2 and the superficial gas velocity ranges from 7.6 to 10.2 m/s. The pressure drop, apparent solids holdups, average slip velocity and solids-to-air mass flow ratio under different operating conditions were obtained. The results showed that the riser total pressure drop increased sharply with bed height in the low elevation but slowly in the high elevation, since the solids holdup was higher in the low region than that in the high region. The solids holdup increased with the increasing of solids mass flux while it decreased with increasing superficial gas velocity. A dense suspension upflow flow (DSU) structure was found only existing in the low elevation while the rest upper region was still in the dilute phase, and the length of DSU flow structure increased with solids mass flux. The average slip velocity was found to be the strong function of apparent solids holdup; increasing apparent solids holdup leads to the increase of slip velocity. The riser total pressure drop and apparent solids holdup increase with the solids-to-air mass flow ratio.

Experimental Investigation of Fine Particles Classification Properties in Gas-Solid Multilevel Particular Fluidization Tower

2013 ◽  
Vol 803 ◽  
pp. 300-307
Author(s):  
Hui Yang ◽  
Dong Yu Wan ◽  
Chang Qing Cao
Keyword(s):  
Pressure Drop ◽  
Quartz Sand ◽  
Fine Particles ◽  
Solid Phase ◽  
Sand Particle ◽  
Gas Velocity ◽  
Experimental Conditions ◽  
Cross Sectional ◽  
Superficial Gas Velocity ◽  
Rectangular Body

The fine particles classification properties in a gas-solid multilevel particular fluidization tower (MPFT) with the rectangular body of 2.4 m in height and 0.032 m2in cross sectional area, five tower plates of 0.39 m in length and 0.08 m in width and 0.005 m in thickness were investigated using two different properties particles, talc particle and quarts sand particle, as solid phase and air as gas phase. It was found from the experimental results that the pressure drop increases with increasing superficial gas velocity. And the spread of pressure drop was gradually decreased from top to bottom in the tower. The grade efficiency for talc powder particle (dp= 10 μm) attained 78.78% and d95 reached 12.84 μm atUg= 0.122 m/s. Meanwhile, for quartz sand particle (dp= 10 μm), the grade efficiency attained 92.80% and d95 reached 12.58 μm atUg= 0.139 m/s. The grade efficiency for the two different properties particles both increases with decreasing feed rate at these experimental conditions in this work. The particle size distribution range of overflow particle increases a little with increasing circulating gas velocity. The grade efficiency for quartz sand particle (dp= 10 μm) dropped from 92.56% to 82.70% with increasing different regurgitant rates from 0 to 12.5 kg/h.

scholarly journals SIMULASI PENGARUH KECEPATAN GAS TERHADAP KARAKTERISTIK FLUIDISASI PADA FLUIDIZED BED MENGGUNAKAN METODE CFD

POROS ◽  
2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Asyari Daryus Daryus
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Particle Density ◽  
Gas Velocity ◽  
Experiment Data ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Gas Fluidization ◽  
Simulation Results

The gas fluidization velocity or superficial gas velocity entering the fluidized bed will affect the fluidization in fluidized bed. If the superficial velocity is below the minimum fluidization velocity then there is no fluidization, and if it is more than it should be then the fluidization characteristic will be different. To obtain the effect of gas fluidization velocity to fluidization characteristics, it had been conducted the research on lab scale fluidized bed using CFD simulation method validated with the experiment data. The simulations used Gidaspow model for drag force and k-ε model for turbulent flow. From the experiments obtained that the minimum fluidization velocity was 0.4 m/s and the pressure drop was around 700 Pa. The simulation results for pressure drop across the bed were close to the experiment data for the gas fluidization velocity equal and bigger than the minimum fluidization velocity. For the velocity below the minimum fluidization velocity, there was the big differences between the simulation results and the experiment, so the simulation results cannot be used. For the fluidization velocity of 0.4 m/s and 0.45 m/s, fluidized bed showed the bubbling phenomena, and the higher velocity showed the bigger bubble. For the fluidization velocity of 0.50 m/s to 0.70 m/s, the fluidized bed showed the turbulent regime. In this regime, the bubble was breaking instead of growing and there was no clear bed surface observed. The simulation result for particle density showed that if the gas velocity was higher, the density of particles at the base of bed was decreasing since many of the particles was moving upwards. The particle density was lower in this regime than that of bubbling regime.

Hydrodynamic Studies on Three-Phase Combined (Internal & External) Loop Airlift Fluidized Bed Reactor Using Newtonian and non-Newtonian Liquids: Minimum Fluidization Velocity and Liquid Holdup

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Sivakumar Venkatachalam ◽  
Akilamudhan Palaniappan ◽  
Kannan Kandasamy
Keyword(s):  
Fluidized Bed Reactor ◽  
Newtonian Fluids ◽  
Experimental Results ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Newtonian Liquids ◽  
Superficial Gas Velocity

A novel combined airlift loop fluidized bed reactor was proposed in this work. The internal and external loops were combined and the hydrodynamic parameters like minimum fluidization velocity and liquid holdup were studied for Newtonian and non-Newtonian fluids. Studies were conducted using Newtonian fluids of water, n-butanol, 60% and 80% glycerol and non - Newtonian fluids such as 0.25%, 0.6% and 1.0% Carboxy Methyl Cellulose (CMC) aqueous solutions were employed in the liquid phases. Spheres, Bearl saddle and Raschig ring with different sizes were used as solid phase. The experimental results indicated that the increase in particle size and sphericity increased minimum fluidization velocity whereas increase in superficial gas velocity decreased minimum fluidization velocity. In addition, the liquid holdup increased with increase in particle size and superficial liquid velocity. Furthermore, an increase in superficial gas velocity decreased the liquid holdup for Newtonian and non-Newtonian systems. Two separate correlations were developed to predict the minimum fluidization velocity and liquid holdup based on the experimental results for both Newtonian and non-Newtonian liquids for a wide range of operating conditions. The capability of the proposed correlation for minimum fluidization velocity and liquid holdup was examined and reasonable agreement between predicted and experimental results of Newtonian and non-Newtonian liquids suggested the applicability of the proposed correlations.

scholarly journals Modeling of the Minimum Fluidization Velocity and the Incipient Fluidization Pressure Drop in a Conical Fluidized Bed with Negative Pressure

2020 ◽  
Vol 10 (24) ◽  
pp. 8764
Author(s):  
Sheng Fang ◽  
Yanding Wei ◽  
Lei Fu ◽  
Geng Tian ◽  
Haibin Qu
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Minimum Fluidization Velocity ◽  
Ergun Equation ◽  
Advantages And Disadvantages ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Series Of Experiments ◽  
Superficial Gas Velocity ◽  
Dimensional Analysis Method

The modeling of the minimum fluidization velocity (U0mf) and the incipient fluidization pressure drop (ΔPmf) is a valuable research topic in the fluidization field. In this paper, first, a series of experiments are carried out by changing the particle size and material mass to explore their effects on U0mf and ΔPmf. Then, an Ergun equation modifying method and the dimensional analysis method are used to obtain the modeling correlations of U0mf and ΔPmf by fitting the experimental data, and the advantages and disadvantages of the two methods are discussed. The experimental results show that U0mf increases significantly with increasing particle size but has little relationship with the material mass; ΔPmf increases significantly with increasing material mass but has little relationship with the particle size. Experiments with small particles show a significant increase at large superficial gas velocity; we propose a conjecture that the particles’ collision with the fluidization chamber’s top surface causes this phenomenon. The fitting accuracy of the modified Ergun equation is lower than that of the dimensionless model. When using the Ergun equation modifying method, it is deduced that the gas drag force is approximately 0.8995 times the material total weight at the incipient fluidized state.

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