Modeling of an internally circulating fluidized bed reactor for thermal treatment of industrial solid wastes

Mukadi, L.; Guy, Christophe; Legros, Robert

doi:10.1002/cjce.5450770231

Cited by 22 publications

(15 citation statements)

References 36 publications

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“…According to Hadzismajlovic et al, the particle velocity in the annulus section is uniform except in the conical section at the bottom of the ICFB. The flow of solid particles in the annular section was treated as a plug flow except in the conical section . Since the flow of solid particles in the annular section is not fluidized in our experiments, SRR could be calculated with Equation (1).…”

Section: Methodssupporting

confidence: 80%

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Gujjula

Mangadoddy

2015

Can J Chem Eng

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Hydrodynamic study of gas and solid flow in an internally circulating fluidized bed (ICFB) is made in this paper using a high-speed camera and pressure probes for the laboratory 0.3 m Â 0.27 m column having an internal draft tube. Experiments were conducted using sand particles of Geldart B and Geldart B-D groups. At each run the standard pressure-flow curves for both the draft tube and annular region beds, and the moving wall particle velocity in the annular bed region were measured. The effects of superficial gas velocity, static bed height, and draft tube gap height on pressure drop profiles, solid circulation patterns, and gas bypassing dynamics for the ICFB were investigated extensively. Unlike the conventional CFB, the pressure drop in ICFB is further decreased with superficial gas velocity after the minimum spouting fluidization, followed by yielding a crossover in the pressure drop of the annular bed compared to the draft tube. Pressure drop in the draft tube increases with an increase of static bed height and gap height between the draft tube bottom and the air distributor. The gas bypassing fraction increases with an increase in gap height and decreases with increased bed height and mean particle size. The mechanism governing the solid circulation and the pressure losses in an ICFB has been elaborated based on gas and solid dynamics obtained from the experimental data.

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Section: Methodssupporting

confidence: 80%

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Gujjula

Mangadoddy

2015

Can J Chem Eng

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“…The ICFBs are widely applied as reactors in such processes as heterogeneous catalysis (Al-Mayman and Al-Zahrani 2003), gasification of biomass (Kersten et al 2003), coal and the pyrolysis of plastics (Aguado et al 2003). New possible areas of applications are desulfurization of flue gases and thermal utilization of wastes (Mukadi et al 1999). A basic disadvantage of an ICFB apparatus is related to the scale-up and development of an industrial unit.…”

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confidence: 99%

Periodic Fluctuations of Flow and Porosity in Spouted Beds

Szafran

Kmieć

2006

Transp Porous Med

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The results of experimental investigations of bed flow hydrodynamics in spouted beds are compared with CFD simulations (Eulerian-Eulerian approach) for two different column geometries. The experimental results of bed porosity and fluctuation frequency of mass flow rate of grain in the fountain region are compared with the corresponding results of simulations. The simulation results confirmed the observations of Muir et al. (1990, Chem. Eng. Comm. 88: 153-171) and Yang and Keairns (1978, AlchE Symp. Ser. No. 176 74: 218) that fluctuations of bed flow in DTSB are caused by particle cluster formation in the loading region at the bottom of column.The solids cross into the jet and cover the column inlet and are carried upward periodically through a draft tube. Subsequent figures obtained from simulations, which show stages of particle cluster formation at the entrance of column, exactly match visual observations. The frequency of fluctuations of grain mass flow rate predicted in simulations (∼5-6 Hz) is in the range of that experimentally determined. The fluctuating inflow of solids results in slug formation and explains the vertical variations of height and porosity of the fountain. NotationGravity acceleration (m/s 2 ) h bed Initial height of bed (m) = I Identity tensor

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“…[2][3][4] In an ICFB, a draft tube is inserted into a fluidized bed dividing the bed into two regions. By fluidizing solids in the draft tube at a velocity ϳ5-10 times the minimum fluidizing velocity (U mf ) and the annulus at 0.7-1.5U mf , it is possible to induce a gross circulation of bed material up to the draft tube and down to the annulus region.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, several studies on waste incineration in ICFB have been reported. 3,7,8 However, ICFB incineration study is relatively sparse compared with those in bubbling and circulating fluidized beds.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, the hydrodynamic properties and heat and mass transfer characteristics in the ICFB are adopted from the model of Mukadi et al 3 to determine combustion efficiency of the wastes with the following assumptions: (1) combustion of char and devolatilization of volatiles occur independently, (2) particle flow in the draft tube and annulus region is considered as a plug low, (3) wastes are circulated with the bed material at the same circulation rate, and (4) combustion of wastes in the freeboard region can be ignored.…”

Section: Kinetics In Tgamentioning

confidence: 99%

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Combustion Characteristics of Spent Catalyst and Paper Sludge in an Internally Circulating Fluidized-Bed Combustor

Roh

Jung

Kim

et al. 2005

Journal of the Air & Waste Management Association

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Combustion of spent vacuum residue hydrodesulfurization catalyst and incineration of paper sludge were carried out in thermo-gravimetric analyzer and an internally circulating fluidized-bed (ICFB) reactor. From the thermogravimetric analyzer-differential thermo-gravimetric curves, the pre-exponential factors and activation energies are determined at the divided temperature regions, and the thermo-gravimetric analysis patterns can be predicted by the kinetic equations. The effects of bed temperature, gas velocity in the draft tube and annulus, solid circulation rate, and waste feed rate on combustion efficiency of the wastes have been determined in an ICFB from the experiments and the model studies. The ICFB combustor exhibits uniform temperature distribution along the bed height with high combustion efficiency (Ͼ90%). The combustion efficiency increases with increasing reaction temperature, gas velocity in the annulus region, and solid circulation rate and decreases with increasing waste feed rate and gas velocity in the draft tube. The simulated data from the kinetic equation and the hydrodynamic models predict the experimental data reasonably well. INTRODUCTIONRecently, most refinery companies installed desulfurization processes to produce light oils from cracking of heavy oils. Consequently, large amounts of catalysts in the crackers are deactivated because of the deposition of vanadium and coke during the cracking reaction. Nickel (Ni), vanadium (V), and coke in the raw oil are deposited on the hydrodesulphurization catalyst or inside pore of the catalyst, and the weight is increased Ͼ50%. In Korea, spent hydrodesulphurization catalysts are producing Ͼ4500 t/yr from hydrodesulphurization processes, and it must be treated properly without environmental pollution. To treat this spent catalysts, there are three methods available, including regeneration of spent catalyst for additional use, recovery of valuable metals (Co, V, and Ni) after combustion of coke in the catalyst, and solidification after melting of the catalyst for landfilling. During the regeneration of the deactivated catalyst, it is necessary to remove coke and sulfur from the combustion of spent catalysts.The production of paper sludge has been also increased because of the large quantity of industrial wastewater from paper mills. Typical wastewater treatment processes generate great quantities of sludge from either primary (clarifiers) or secondary treatments (anaerobic and aerobic biological processes). As an example in the mechanical pulping industry, the removed primary and secondary sludge, ϳ25 and 12 kg/t processed pulp, respectively, that make up sludge disposal is a major environmental problem. 1 Until now, sludge landfill is a preferred disposal method; however, landfill is no longer a viable solution because of the decrease in space available for landfills, the rising tipping fees, and the growing concern about their impacts on the environment. Thermal utilization of sludge may be an economic and sustainable disposal solution. I...

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Modeling of an internally circulating fluidized bed reactor for thermal treatment of industrial solid wastes

Cited by 22 publications

References 36 publications

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Periodic Fluctuations of Flow and Porosity in Spouted Beds

Combustion Characteristics of Spent Catalyst and Paper Sludge in an Internally Circulating Fluidized-Bed Combustor

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