• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1057-1062
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• 2008

To overcome disadvantages of conventional two interconnected fluidized beds system, a novel two-interconnected fluidized bed process has been adopted to 3kW chemical-looping combustor. This system has two bubbling beds, solid injection nozzles, solid conveying lines, and downcomers. In this study, effects of operating variables such as gas velocity through the solid injection nozzle, fluidizing velocity, solid height, geometry of solid intake hole, bed temperature on solid circulation rate have been investigated in a 3kW chemical-looping combustor. The solid circulation rate increased as the solid height and the opening area of solid intake holes increased. The effect of the fluidizing velocity and the bed temperature were negligible. Moreover, long-term operation of continuous solid circulation up to 50 hours has been performed to check feasibility of stable operation. The pressure drop profiles in the bubbling beds and the downcomers were maintained steadily and solid circulation was smooth and stable.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.510-515
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• 1994

Yttria-stabilized zirconia(YSZ) films were prepared onto p-type (100) silicon wafer by a plasma-enhanced metallorganic chemical vapor deposition(PE MO CVD) processing involving the application of vapor mixture of tri(2.2.6.6-tetramethyl-3, 5-heptanate) yttrium$[Y(DPM)_3]$, zirconiumtriflouracethyla cetonate$(Zr(tfacac)_4$ and oxygen gas. The x-ray diffraction(XRD) and fourier transform infrared spectra(FT1R) results showed that the deposited YSZ films had a single cubic phase. $Y_2O_3$ content of YSZ film was analyzed by PIXE(partic1e induced x-ray emission). The experimental results by PIXE revealed that 12.lmol%, 20.4mol% and 31.6mol% $Y_2O_3$ could be obtained as the $Y(DPM)_3$ bubbling temperature varied at $160^{\circ}C, 165^{\circ}C$ and $170^{\circ}C$ respectively. The increase of $Y(DPM)_3$ bubbling temperature caused shifting flat band voltage to have a negative value.

• YAKHAK HOEJI
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• v.38 no.1
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• pp.57-66
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• 1994

We studied the effect of eicosanoids on the content of energy metabolites and the intrasynaptosomal $Ca^{++}([Ca^{++}]_i)$ concentration in cerebral ischemic rats. An ischemic model was made by bilateral carotid artery ligation (BCAL) and by incubation of synaptosomes under aglycemic and $N_2$ gas bubbling condition. The content of ATP, creatine phosphate and glucose decreased at 15 minutes after BCAL while that of lactate increased in male Wistar rats. Oral administration of EPA(100 mg/ml/Kg/day) or DHA(16 mg/ml/Kg/day) for 6 weeks improved both the decreases and the increase of the cerebral energy metabolites. In addition, the increase of $[Ca^{++}]_i$, under BACL was suppressed by EPA or DHA treatment. When the both Wistar rats and SHR were administered orally with EPA or DHA for 6 weeks, the effect on the increase of $[Ca^{++}]_i$ under ischemia by $N_2$ gas bubbling were protected. From these results, it may be that EPA or DHA treatment were greatly contributed to preservation of ischemic cerebral energy metabolism and $Ca^{++}$ concentration.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.589-596
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• 2016

Effects of pressure, temperature, gas velocity, and fuel flow rate on reduction of three oxygen carriers, SDN70, OC-1, OC-2, were measured and investigated in a pressurized bubbling fluidized bed reactor. Among three oxygen carriers OC-2 was selected as the best oxygen carrier in view of fuel conversion and $CO_2$ selectivity. However, all oxygen carriers showed good reactivity even at high pressure conditions. SDN70 particle showed maximum reactivity at $900^{\circ}C$ and low reactivity at $950^{\circ}C$. However, reactivity decay of OC-1 and OC-2 particles at high temperature condition was negligible. The fuel conversion and the $CO_2$ selectivity slightly decreased as the gas velocity increased, whereas they are slightly increased as the fuel concentration increased.

• Resources Recycling
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• v.15 no.1 s.69
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• pp.46-57
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• 2006

For the development of combustion technology of RDF(refuse derived fuel), combustion characteristics are examined in bubbling fluidized bed, circulating fluidized bed, continuos combustor and batch type combustor. The characteristics of combustion and exhaust gas has been compared and analyzed in many type of combustion facilities, which has been utilized as basic data for the advanced research of specified RDF combustion facility. Stable combustion has been observed in bubbling and circulating fluidized bed from controled operating condition like the proper feeding rate and superficial gas velocity. In circulating fluidized bed, concentration of NOx has been increased with the operating condition by the fuel-NO and oxygen reaction and $SO_2$ can be considered not to be produced in RDF fluidized bed from very low concentration in flue gas. HCl concentration is 36.4 ppm as average value and lower than standard emission value, but the counter plan is needed. Shaped RDF and fluff RDF have been compared in continuos combustor and batch type combustor and shaped RDF shows benefit for the stable heat recovery and gas emission shows similar value and characteristics.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.499-505
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• 2010

In this study, hydrodynamics and reaction characteristic of K-based solid sorbents for $CO_2$ capture were investigated using a continuous system composed of two bubbling fluidized-bed reactors(1.2 m tall bed with 0.11 m i.d.). Potassium-based dry sorbents manufactured by the Korea Electric Power Research Institute were used, which were composed of $K_2CO_3$ of 35% for $CO_2$ absorption and supporters of 65% for mechanical strength. The continuous system consists of two bubbling fluidized-bed reactors, solid injection nozzle, riser, chiller, analyzer and heater for regeneration reaction. The minimum fluidizing velocity of the continuous system was 0.0088 m/s and the solid circulation rate measured was $10.3kg/m^2{\cdot}s$ at 1.05 m/s velocity of the solid injection nozzle. The $CO_2$ concentration of the simulated gas was about 10 vol% in dry basis. Reaction temperature in carbonator and regenerator were maintained about $70^{\circ}C$ and $200^{\circ}C$, respectively. Differential pressures, which were maintained in carbonator and regenerator, were about $415mmH_2O$ and $350mmH_2O$, respectively. In order to find out reaction characteristics of dry sorbents, several experiments were performed according to various experimental conditions such as $H_2O$ content(7.28~19.66%) in feed gas, velocity (0.053~0.103 m/s) of simulated gas, temperature($60{\sim}80^{\circ}C$) of a carbonator, temperature($150{\sim}200^{\circ}C$) of a regenerator and solid circulation rate($7.0{\sim}10.3kg/m^2{\cdot}s$). The respective data of operating variables were saved and analyzed after maintaining one hour in a stable manner. As a result of continuous operation, $CO_2$ removal tended to increase by increasing $H_2O$ content in feed gas, temperature of a regenerator and solid circulation rate and to decrease by increasing temperature of a carbonator and gas velocity in a carbonator.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.99-105
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• 1997

In the paper, aging of insulating oil in pole transformer has been studied by performing accelerated thermal aging test. Dissolved gases were extracted by air bubbling method. Concentration of dissolved gases were modified by extraction ratio of each gases in insulating oil. Aging of insulating materials were proceeded by thermal degradation and oxidation reaction. Both of the reactions followed zeroch order kinetics. Formation rate equations for hydrocarbons, carbon oxides, and hydrogen were derived. It was conformed by gas analysis and UV-Visible spectrophotometric method that iron core and copper coil in pole transformer act as catalyst during the aging process.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.24-33
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• 1997

In this paper, aging of insulating oil in pole transformer has been studied by performing accelerated thermal aging test. Dissolved gases were extracted by air bubbling method. Concentration of dissolved gases were modified by extraction ratio of each gases in insulting oil. Aging of insulting materials were proceeded by thermal degradation and oxidation reaction. Both of the reactions followed zeroth order kinetics. Formation rate equations for hydrocarbons, carbon oxides, and hydrogen were derived. It was conformed by gas analysis and UV-visible spectrophotometric method that iron core and copper coil in pole transformer act as catalyst during the aging process.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.693-699
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• 2001

ChlorophyII destruction by irradiation in linoleic acid in methanol system was studied. ChlorophyII b standard (3 ppm) was added into methanol solution containing 1% of linoleic acid, and the sample was irradiated up to 20 kGy with or without nitrogen gas-bubbling. The content of chlorophyII b was analyzed by HPLC, and Hunter color value and UV-visible spectra were analyzed during 6 hr of photooxidation. The content of chlorophyll was reduced by irradiation and completely destroyed at 2.517 kGy. The model system with nitrogen gas-bubbling did not develop the lipid oxidation after irradiation or photooxidation at 20 kGy UV-visible spectra showed decreasing values of optical density by increase of irradiation doses, supporting the destruction of chlorophyII b. The results indicate that irradiation technology can be applied to reduce or eliminate the residual chlorophyII and to prolong the shelf-life of oil products.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.57-60
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• 2006

The instability analysis of submerged gas flow into liquid is studied, which assumes gas and liquid as viscous and irrotational. At low mass flow rate of gas, injected gas plume is collection of bubbles, and increase of gas flow rate makes plume as a jet. It is well known that the transition from bubbling to jetting occurs in the transonic region. But previous works neglect viscous effect of gas flow into liquid. This paper concerns about an application of viscous potential flow theory in cylindrical gas flow into liquid. The growth rate versus wave number and mach number is compared with various condition including inviscid and viscous flow.