• Advances in environmental research
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• v.7 no.1
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• pp.29-37
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• 2018

A simple mathematical model for predicting fixed bed adsorption dynamics is described. The model is characterized by a linear adsorption isotherm and a linear driving force expression for mass transfer. Its analytic solution can be approximated with an algebraic equation in closed form which is easily evaluated by spreadsheet computation. To demonstrate one application of the fixed bed model, a previously published adsorption system is used as a case study in this work. The adsorption system examined here describes chromium breakthrough in a fixed bed adsorber packed with imidazole functionalized adsorbent particles and is characterized by a nonlinear adsorption isotherm. However, the equilibrium behavior of the fixed bed adsorber is in essence governed by a linear adsorption isotherm due to the use of a low influent chromium concentration. It is shown that chromium breakthrough is predicted reasonably well by the fixed bed model. The model's parameters can be easily extracted from independent batch experiments. The proposed modeling approach is very simple and rapid, and only Excel is used for computation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.226-233
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• 1990

Fixed bed is known to be an effective heat transfer augmentation device which could be applied to heat exchangers. In this study, pressure drop in vertical cylindrical and annular fixed beds with air flowing through was experimentally investigated. Based on the experimental data and some analytical considerations, the demensionless correlation of pressure drop has been determined and shown in empirical forms. In particular, the experimental equation for the pressure drop was derived using the particle diameter and the bed diameter as variables, which would be more practical and useful in the design of heat transfer devices, instead of void fraction which had been used previously as the major variables by others. The present empirical equation obtained for the cylindrical fixed bed were found to be applicable also to an annular fixed bed when the concept of effective diameter was introduced.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.234-242
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• 1990

In this study, heat transfer characteristics of vertical fixed bed with air flowing through were experimentally investigated. The experiments were conducted for cases where heat was transfer steady state conditions from an immersed cylindrical heated to the surrounding fixed ved of steel balls. Based on the experimental data, the optimum conditions for heat transfer augmentation have been determined and shows in empirical forms. For the same power loss, comparison of heat transfer effect between the fixed bed and single phase forced convection device indicates that both miniaturization of heat exchange device and heat transfer augmentation at low flow velocity are possible by application of the fixed bed to heat exchangers. The present results could provide a useful design information for the heat exchangers where fixed beds are used.

• Journal of Life Science
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• v.9 no.6
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• pp.698-703
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• 1999

For the nitrate removal in recirculating aquaculture system, a denitrifying bacterium, Pseudomonas fluorescens, was isolated from municipal sewage and the cells were immobilized in modified-polyvinly alchol (PVA) gel beads. The immobilized cells in both the fixed-and fluidized-bed reactors showed 98% of denitrification efficiency with 6hr HRT, and the removal efficiency of total organic carbon (TOC) was above 90%. Form scanning electron microscopy (SEM) observation, it was known that biofilm formed in fixed-bed reactor was thicker than that formed in fluidized-bed reactor as operation time passed.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.29-32
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• 2014

The practical route for disposal of sewage sludge becomes energy recovery by combustion after its ocean dumping is banned in 2012 in Korea. Due to the high moisture content, however, sewage sludge is required to be dried before transport and combustion. In this study, pyrolysis and combustion characteristics of dried sewage sludge was investigated in a small-scale fixed bed reactor in order to provide fundamental data for energy recovery of the fuel. As the first step of combustion, the primary products of pyrolysis were analyzed in a fixed bed reactor for the condensable volatiles (tar), non-condensable gases, and char. For the combustion characteristics, another fixed bed reactor was constructed to monitor the weight and temperature of the fuel particles during ignition and combustion under different air flow rates. The test results were used to derive the ignition and burning rates.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.773-782
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• 1998

The adsorption experiment of phenol(Ph) from aqueous solution on granular activated carbon was studied in order to design the fixed-bed adsorption column. The experimental data were analyzed by unsteady-state, one-dimensional heterogeneous model. Finite element method(FEM) was applied to analyze the sensitivity of parameter and to predict the fixed-bed adsorption column performance on operation variable changes. The prediction model showed similar effect to mass transfer and intraparticle diffusion coefficient changes suggesting that both parameter present mass transfer rate limits for GAC-phenol system. The Freundlich constants had a greater effect than kinetic parameters for the performance of fixed-bed adsorption column. FEM solution facilitated prediction of concentration history in solution and within adsorbent particle.

• Journal of Biosystems Engineering
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• v.31 no.5 s.118
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• pp.416-422
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• 2006

Drying characteristics of green onion and onion during fluidized and fixed bed drying were investigated and compared. Sliced peen onion and onion were dried at drying air temperature of 45, 55, and $65^{\circ}C$. Drying air velocity during fluidized bed drying was adjusted with drying time at each drying temperature. Drying time to reach a given final moisture content was shorten in fluidized bed drying than in fixed bed drying - for drying temperature of 45, 55, and $65^{\circ}C$, the differences were 60, 60, and 50 min for green onion and 360, 180, and 60 min for onion. Drying constant (K) was greatly affected by drying method and drying temperature. Terminal velocity under fluidized bed drying was decreased exponentially for green onion and linearly (or onion with increase of drying temperature. Also, terminal velocity had linear relationship with moisture content for both green onion and onion.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.53-60
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• 2014

Adsorption of phenol on activated carbon in a fixed bed was studied. The effects of fixed-bed length, superficial velocity (flow rate) and particle size of adsorbent on fixed-bed performance were investigated. Some characteristic parameters such as the breakthrough time ($t_{0.05}$), saturation time ($t_{0.95}$), length of mass transfer zone ($L_{MTZ}$), adsorptive capacity (W), and adsorption rate constant ($K_a$) were derived from the breakthrough curves. Adsorbent particle sizes significantly affected the shape of the breakthrough curve. Larger particle sizes resulted in an earlier breakthrough, a longer $L_{MTZ}$ and a lower adsorption rate. Superficial velocity was a critical factor for the external mass transfer during fixed-bed adsorption process. The external mass transfer resistance was dominant as increasing superficial velocity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.107-110
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• 1982

Fixed bed drying method was selected to reduce the initial drying time of squid and the effects of drying air temperature and bed height on the drying rate were investigated, with following results. 1. The drying rate in the fixed bed dryer was faster than that of natural convection type dryer heated indirectly and that of hot air dryer heated directly. 2, Shirai-equation was applicable to squid being dried. Using the equation, drying rate constant obtained was as shown in table 1.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.75-78
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• 2006

With the increasing environmental consideration and stricter regulations waste gasification is considered to be more attractive technology than conventional incineration for energy recovery as well as material recycling. The experiment for combustible waste was performed In the fixed bed gasifier to investigate the gasification behavior with the operating conditions in a 5ton/day fixed bed gasifier The experiments of operation with 10-50 hours were carried out to determine the effects of bed temperature and oxygen/waste rat io on the syngas composition, calorific value and carbon conversion. The calorific values of the produced syngas decreased with an Increase of bed temperature because combust ion reaet ion more act ively happened. The syngas composition of wood waste gasification is CO: 34.4%, $H_2: 10.7%,\;CH_4: 6.0%,\;CO_2: 48.9%$ and that of RPF is CO: 33.9%, $H_2: 26.1%,\;CH_4: 10.7%,\;CO_2: 29.2%$. The average calorific values of produced gas were about $1,933kcal/Nm^3,\;2,863kcal/Nm^3$, respectively