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1.
Dong Hyun Lee Sung Soo Park Won Woong Choi Duk Joon Kim Ji-Heung Kim Young Kwan Lee Sang Jun Sim Sang Done Kim 《Korean Journal of Chemical Engineering》2003,20(6):1166-1169
Transient behavior of the bed collapse after shut-off the gas supply into a three-phase fluidized bed was determined. Experiments
were carried out in a 210-mm diameter half-tube acrylic column having a 1.8 m-high test section. The polymer beads (d
p
=3.2 mm,ρ
s
= 1,280 kg/m3) were fluidized by cocurrent flow of deionized water and air. The transient behavior of the bed collapse after cut-off the
gas supply to the bed was monitored by a video camera (30 frames/s). The dense bed surface height was measured from the image
of videotape. At lower liquid velocity, the dense bed surface increases with the elapsed time and then reaches a bed height,
whereas at higher liquid velocity the dense bed surface increases sharply with the elapsed time, then decreases and reaches
the bed height corresponding to the liquid-solid fluidized beds (water-polymer beads). 相似文献
2.
Chan Jin Park 《Korean Journal of Chemical Engineering》1999,16(5):694-697
The hydrodynamic characteristics of an air-lift activated carbon slurry column with external looping were investigated to find the optimal operating conditions of the slurry adsorption process that is frequently used as wastewater treatment, biological air pollutant removal and other environmental treatments. The experiments were conducted at different concentrations of adsorbents and gas inputs in the air-lift bubble column having external looping as batchwise contactor. The hydrodynamic behaviors were estimated with the residence time tracing of slurry adsorbents and gas holdups. The mixing characteristics were analyzed to find the best operating condition of an air-lift bubble column for the adsorbing equipment, and the performance of column was compared with that of internal looping. 相似文献
3.
Jae Uk Jung Wooseok Nam Ki June Yoon Gui Young Han 《Korean Journal of Chemical Engineering》2007,24(4):674-678
A fluidized bed reactor made of quartz tube with an I.D. of 0.055 m and a height of 1.0 m was employed for the thermocatalytic
decomposition of methane to produce CO2 — free hydrogen. The fluidized bed was used for continuous withdrawal of the carbon products from the reactor. Two kinds
of carbon catalysts — activated carbon and carbon black — were employed in order to compare their catalytic activities for
the decomposition of methane in the fluidized bed. The thermocatalytic decomposition of methane was carried out in a temperature
range of 800–925°C, using a methane gas velocity of 1.0–3.0 U
mf
and an operating pressure of 1.0 atm. Distinctive difference was observed in the catalytic activities of two carbon catalysts.
The activated carbon catalyst exhibited higher initial activity which decreased significantly with time. However, the carbon
black catalyst exhibited somewhat lower initial activity compared to the activated carbon catalyst, but its activity quickly
reached a quasi-steady state and was sustained over time. Surfaces of the carbon catalysts before and after the reaction were
observed by SEM. The effect of various operating parameters such as the reaction temperature and the gas velocity on the reaction
rate was investigated. 相似文献
4.
Tae Young Kim Seung Jai Kim Sung Young Cho 《Korean Journal of Chemical Engineering》2001,18(5):755-760
The adsorption characteristics of 2,4-dinitrophenol from water onto a granular activated carbon, F-400, were studied at pH
4.3, 7 and 10. Adsorption equilibria of 2,4-dinitrophenol on GAC could be represented by Sips equation. Equilibrium capacity
increased with decreasing pH. The differences in the rates of adsorption are primarily attributable to the differences in
the equilibrium at the various pHs. Intraparticle diffusion was explained by surface diffusion mechanism. An adsorption model
based on the linear driving force approximation (LDFA) was used for simulating the adsorption behavior of 2,4-dinitrophenol
in a fixed bed adsorber.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8-10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University. 相似文献
5.
Byoung Chul Kim Young Han Kim Takuji Yamamoto 《Korean Journal of Chemical Engineering》2008,25(5):1140-1144
Dye is difficult to remove from aqueous solution with common adsorbents due to its large molecular size. Mesoporous bamboo
activated carbon is utilized in the adsorption of Black 5, Red E and phenol. The adsorption performance of the carbon is experimentally
examined along with the characterization of the adsorbent. The comparison of adsorption capacity of the bamboo activated carbon
with that of coconut activated carbon and carbon cryogel indicates that the large volume of mesopore in the carbon helps the
expansion of adsorption capacity. Microscopic observation, the measurement of pore characteristics and fitting to the adsorption
isotherms are conducted in the characterization of the bamboo activated carbon. 相似文献
6.
The potential use of Mowital B30H resin immobilized dried activated sludge as a substitute for granular activated carbon for removing phenol from aqueous solution was examined in a continuous packed bed reactor as a function of flow rate and inlet phenol concentration. The working sorption pH value was determined as 1.0 for both the sorbents, and packed bed sorption studies were performed at this pH value. The maximum specific uptakes, total adsorbed quantities, and total removals of phenol related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different flow rates and different inlet phenol concentrations for each sorbent. At the lowest flow rate of 0.8 mL/min and at the inlet phenol concentration of 500 mg/L, the maximum specific uptakes and total removals of phenol were 84.0 mg/g and 27.6%, respectively, for granular activated carbon and 9.0 mg/g and 9.3%, respectively, for immobilized dried activated sludge. Data confirmed that total removals of phenol decreased with increasing flow rate and inlet phenol concentration for both immobilized dried activated sludge and granular activated carbon systems. 相似文献
7.
Jun Sik Kim Hak Ki Kim Sang Bong Lee Myoung Jae Choi Kyu Wan Lee Yong Kang 《Korean Journal of Chemical Engineering》2001,18(4):463-467
Characteristics of CO2 hydrogenation were investigated in a fluidized bed reactor (0.052 m IDxl.5 m in height). Coprecipitated Fe-Cu-K-Al catalyst
(dρ=75–90 Μm) was used as a fluidized solid phase. It was found that the CO2 conversion decreases but the CO selectivity increases, whereas the space-time-yield attains maximum values with increasing
gas velocity. The CO2 conversion has increased, but CO selectivity has decreased with increasing hydrogenation temperature, pressure or H2/CO2 ratio in the fluidized bed reactor. Also, the CO, conversion and olefin selectivity appeared to be higher in the fluidized
bed reactor than those of the fixed bed reactor.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University 相似文献
8.
9.
Characteristics of particle flow in the standpipes of a 10 cm I.D.×120 cm high fluidized bed were investigated. The standpipes
used in this experiment were vertical overflow and vertical underflow standpipes. Sand particles and polyethylene powders
were employed as the bed materials. The effects of standpipe diameter, gas velocity and particle properties on the solid flow
rate were determined. The experimental results showed that the flow behaviors of solids through the overflow and underflow
standpipes are different with variations of operating conditions. For both standpipes, the mass flow rate of solids was strongly
dependent on the standpipe diameter. For the overflow standpipe, the increase of gas velocity increased the solids flow rate.
But for the underflow standpipe it decreased the solid flow rate. From the measured pressure drops, solid fractions in the
standpipes were determined by the momentum balance. The obtained experimental data of solids mass flow rate were well correlated
with the pertinent dimensionless groups for underflow as well as overflow standpipes. 相似文献
10.
Seoung Hyun Kim Aneeta Bidkar Huu Hao Ngo Saravanamuthu Vigneswaran Hee Moon 《Korean Journal of Chemical Engineering》2001,18(2):163-169
Removal of a synthetic organic herbicide, metsulfuron-methyl (MSM), from aqueous solutions has been studied in batch and stirred
tank adsorbers charged with granular activated carbon particles. Two kinetic parameters, film mass transfer and intraparticle
diffusion coefficients, were estimated from concentration decay curves obtained in the batch adsorber. Based on these kinetic
parameters, the concentration profiles measured in the stirred tank adsorber were simulated. From experimental and simulated
results, it was proven that the film mass transfer at external surfaces of carbon particles controls the overall mass transfer,
particularly at low mixing (rotation of blades), during the adsorption of MSM by granular activated carbon particles. 相似文献
11.
Jong-Hyeun Choi Jin-Ho Park Won-Myung Choung Yong Kang Sang Done Kim 《Korean Journal of Chemical Engineering》1995,12(2):141-145
The hydrodynamic properties in the riser and standpipe. and the cyclone efficiency have been determined in a circulating fluidized
bed (CFB) unit consisting of a riser (0.05 m-IDX3.8 m high), a standpipe (0.068 m-IDX2.5 m high) as a primary cyclone/bubbling
fluidized bed, and a secondary cyclone. Silica gel powder (mean diameter = 46 μm) was used as the bed material. The effects
of gas velocity in the riser and initial solid loading on the solid circulation rate, and the solid holdups in the riser and
standpipe have been determined. The effects of gas velocity in the standpipe on the efficiencies of primary and secondary
cyclones have been also determined as functions of solid circulation rate and solid entrainment rate. The solid circulation
rate increases with increases in the gas velocity in the riser and in the initial solid loading. The efficiencies of primary
and secondary cyclones increase with an increase in the gas velocity in the riser. However, the efficiency of primary cyclone
decreases and that of secondary cyclone increases slightly, with an increase in the gas velocity in the standpipe. 相似文献
12.
Sung-Yong Cho Seung-Shik Park Seung-Jai Kim Tae-Young Kim 《Korean Journal of Chemical Engineering》2006,23(4):638-644
Adsorption and desorption characteristics of the 2-methyl-4-chlorophenoxyacetic acid (MCPA) from aqueous solution onto the
activated carbon (GAC, F-400) were studied. Adsorption equilibrium capacities of the MCPA increased with decreasing pH and
temperature of the solution. Adsorption equilibrium of the MCPA could be represented by the Sips equation. The internal diffusion
coefficients were determined by comparing the experimental concentration decay curves with those predicted from surface diffusion
model and pore diffusion model. The adsorption model based on the linear driving force approximation (LDFA) was used for simulating
the adsorption behavior of the MCPA in a fixed bed. Over ninety five percent desorption of the MCPA could be obtained using
distilled water. 相似文献
13.
Growth of carbon nanofibers on activated carbon fiber fabrics 总被引:2,自引:0,他引:2
Activated carbon fiber fabrics, an excellent adsorbent, were used as catalyst supports to grow carbon nanofibers. Because of the microporous structure of the activated carbon fibers, the catalysts could be distributed uniformly on the carbon surface. Based on this concept, the carbon nanofibers can be grown directly on the activated carbon fiber fabrics. We demonstrate that carbon nanofibers with a diameter between 20 and 50 nm for most of the fibers can be synthesized uniformly and densely on activated carbon fiber fabrics, impregnated by nickel nitrate catalyst precursor, using catalytic chemical vapor deposition. Although the carbon nanofibers are not straight with a crooked morphology, they form a three-dimensional network structure. Structure characterizations by TEM and XRD indicate that the carbon nanofibers have a turbostratic graphite structure and the graphite layers are stacked with a herringbone structure. 相似文献
14.
快速流化床入口结构对床层流动特性的影响 总被引:1,自引:0,他引:1
在直径0.14m、高11m的快速流化床装置上,考察了床层入口结构及进风系统对床层流动特性,尤其是截面平均空隙率轴向分布的影响。实验结果表明,由于入口结构的改变,床内两相流动将受到严重影响。当入口结构为弱约束时,截面平均空隙率可为S型轴向分布。 相似文献
15.
Jung A Rhim 《Korean Journal of Chemical Engineering》2006,23(1):38-42
The dissolved organic carbon (DOC) properties for the influent of the BAC pilot plant have shown a 42% biodegradable fraction
and a 58% non-biodegradable fraction. The biodegradable dissolved organic carbon (BDOC) was degraded entirely by biodegradation;
the removal efficiency was 65–83%. The BDOC removal efficiency at empty bed contact time (EBCT) 15 minutes was larger than
at EBCT 8 minutes. At increasing EBCT, a more slowly biodegradable fraction of BDOC (H2) was utilized. The non-biodegradable dissolved organic carbon (NBDOC) was removed mostly by adsorption, and the removal amount
was 24–58%. Therefore, the DOC was removed by adsorption and biodegradation; the removal efficiency by biodegradation was
31%, and that by adsorption was 24%. The breakthrough behaviors of DOC and NBDOC continued to be saturated as the bed volume
increased, whereas the BDOC breakthrough curves maintained a certain ratio according to the bed volume. 相似文献
16.
Adsorption characteristics according to polarity of acetone and toluene vapors on coconut based activated carbon were investigated
by using a fixed bed reactor. Single vapor and binary vapor adsorption of acetone and toluene were conducted. In the single
vapor system, the equilibrium adsorption capacity of toluene vapor on activated carbon was five times higher than that of
acetone vapor because of polarity difference between adsorbent and adsorbate. The breakthrough curve of acetone vapor in the
binary vapor was quite different from that of single acetone vapor. Acetone adsorbed in the binary vapor was substituted with
toluene due to the affinity difference during adsorption process and its outlet concentration increased to 1.6 times than
inlet concentration. The temperature changes in activated carbon bed during adsorption of acetone vapor and toluene vapor
occurred in the time ranges of 10–30 min. The temperature change for acetone vapor adsorption was about 3 °C; however, that
for toluene vapor adsorption was increased to 33 °C maximally. 相似文献
17.
S. Biniak M. Pakuła W. Darlewski A. Świątkowski P. Kula 《Journal of Applied Electrochemistry》2009,39(5):593-600
Commercial activated carbon (Norit R3ex), de-mineralised with conc. HF and HCl, was oxidised (conc. HNO3) and heat-treated at various temperatures (180, 300 and 420 °C). The physicochemical properties of the samples obtained were
characterised by selective neutralisation and pH-metric titration of surface functional groups (acid–base properties), thermogravimetry
(thermal stability—TG), FTIR spectroscopy (chemical structure) and low-temperature nitrogen adsorption (BET surface area).
Thermal treatment of the carbon materials caused the surface functional groups to decompose; in consequence, the chemical
properties of the carbon surfaces changed. Cyclic voltammetric studies were carried out on all samples using a powdered activated
carbon electrode (PACE) and a carbon paste electrode (CPE), as were electrochemical measurements in aqueous electrolyte solutions
(0.1 M HNO3 or NaNO3) in the presence of Cu2+ ions acting as a depolariser. The shapes of the cyclic voltammograms varied according to the form of the electrodes (powder
or paste) and to the changes in the surface chemical structure of the carbons. The electrochemical behaviour of the carbons
depended on the presence of oxygen-containing surface functional groups. The peak potentials and their charge for the redox
reactions of copper ions depended on their interaction with the carbon surface. 相似文献
18.
Elemental mercury vapor capture by powdered activated carbon in a fluidized bed reactor 总被引:2,自引:0,他引:2
A bubbling fluidized bed of inert material was used to increase the activated carbon residence time in the reaction zone and to improve its performance for mercury vapor capture. Elemental mercury capture experiments were conducted at 100 °C in a purposely designed 65 mm ID lab-scale pyrex reactor, that could be operated both in the fluidized bed and in the entrained bed configurations. Commercial powdered activated carbon was pneumatically injected in the reactor and mercury concentration at the outlet was monitored continuously. Experiments were carried out at different inert particle sizes, bed masses, fluidization velocities and carbon feed rates. Experimental results showed that the presence of a bubbling fluidized bed led to an increase of the mercury capture efficiency and, in turn, of the activated carbon utilization. This was explained by the enhanced activated carbon loading and gas-solid contact time that establishes in the reaction zone, because of the large surface area available for activated carbon adhesion/deposition in the fluidized bed. Transient mercury concentration profiles at the bed outlet during the runs were used to discriminate between the controlling phenomena in the process. Experimental data have been analyzed in the light of a phenomenological framework that takes into account the presence of both free and adhered carbon in the reactor as well as mercury saturation of the adsorbent. 相似文献
19.
Experimental measurements of the correlation dimension, Kolmogorov entropy, and Lyapunov exponent of circulating fluidized bed (CFB) chaotic attractors were obtained by recording differential pressure and γ-ray porosity time series along the height of a cold experimental CFB operating with 75 μm diameter fluid catalytic cracking (FCC) catalyst. The attractor dimension did not vary with respect to the type of measurement taken. Both differential pressure and localized γ-ray densitometry measurements showed the existence of a low order hydrodynamic attractor, whose dimension varied between 1.5 and 2.0 over the range of gas velocities and solids fluxes studied. Differential pressure measurements indicated that the attractor dimension decreased slightly in the lower section of the CFB and at higher solids fluxes. Localized radial γ-ray bed porosity measurements indicate that the attractor dimension did not significantly vary across the bed cross-section but did show a tendency to be slightly lower near the riser wall. 相似文献
20.
Francesco Miccio Karel Svoboda Jean-Pierre Schosger David Baxter 《Korean Journal of Chemical Engineering》2008,25(4):721-726
The paper deals with a high efficiency process for biomass gasification based on the concept of the internal circulating fluidized
bed (ICFB). A modeling tool has been developed for the prediction of theoretical values for the main species in a syngas produced
by ICFB gasification. A thermodynamic sub-model has been utilized and integrated with a simplified lumped model of the gasifier.
The model predicts H2 concentration up to 61% on water free basis. The comparison with calculations for one stage gasification demonstrates ICFB
process is preferable, no dilution with inert gas occurring. Among the studied variables, the steam/fuel ratio and the fuel
moisture exert the largest influence on the hydrogen yield with percentage changes up to 15% in the explored range of the
variables. 相似文献