• Korean Chemical Engineering Research
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• 제52권1호
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• pp.81-87
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• 2014

고체가 연속적으로 주입되고 배출되는 상온 상압 2단 기포 유동층(내경 0.1 m, 높이1.2 m)의 흐름특성을 조사하고, 운전유속범위를 고찰하였다. 고체는 상부 기포 유동층으로 주입되고, 넘쳐서 기계적 혹은 비기계적 밸브가 없이 단순히 농후상 고체 층으로 이루어진 고체 수송관(standpipe, 내경 0.025 m)를 통하여 하부 기포 유동층의 층으로 주입되며, 하부 유동층을 넘쳐서 고체가 배출되었다. 기체는 하부 유동층을 유동화하고 배출된 후 다시 상부 유동층을 유동화하였다. 기체로는 공기를 사용하였고, 고체로는 입도가 큰 입자(< $1000{\mu}m$, 겉보기 밀도 $3090kg/m^3$)와 입도가 작은 입자(< $100{\mu}m$, 겉보기 밀도 $4400kg/m^3$)를 혼합한 입자를 사용하였으며, 혼합비를 변수로 하였다. 하부 유동층 기체가 고체수송관의 고체흐름을 비우고, 우회하는 조건일 때 하부 유동층 유동화 속도를 붕괴속도로 정의하였다. 본 공정의 운전이 가능한 최대기체유속으로 붕괴속도가 사용될 수 있었다. 붕괴속도는 작은 입자 혼합비가 증가함에 따라 증가하여, 30%에서 가장 큰 값을 나타낸 후, 감소하였다. 붕괴속도의 경향은 고체수송관 상단과 하단 사이의 압력차 경향과 유사하였다. 붕괴속도는 벌크밀도(bulk density)와 정체층 공극률의 함수로 나타내졌으며, 벌크밀도가 증가하면 증가하고, 정체층 공극률이 증가하면 감소하였다.

• 설비공학논문집
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• 제16권3호
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• pp.273-279
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• 2004

A lab-scale fluidized bed heat exchanger for waste gas heat recovery is devised and tested. Compared to our previous works on fluidized bed type system with a single riser, the present heat exchanger system is featured by its multiple (four) risers to handle increased amount of exhaust gas. Particles are introduced to the main hot gas stream alongside the pipe circumference near riser inlets. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

• 대한기계학회논문집B
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• 제24권5호
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• pp.677-686
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• 2000

The characteristics of combustion and of emissions in pressurized fluidized bed combustor are investigated. The pressure of the combustor is fixed at 6 atm, and the combustion temperatures are set to 850, 900, and $950^{\circ}C$. The gas velocities are 0.9, 1.1, and 1.3 m/s. The excess air ratio is varied from 5 to 35%. The coal used in the experiment is Shenhwa coal in China. All experiments are executed at 2m bed height. Consequently, NOx & $N_2O$ concentration in the flue gas is increased with incresing excess air ratio but $SO_2$ concentration is decreased with incresing excess air ratio. CO concentration is maintained below 100ppm at over 15% of excess air ratio.

• 환경위생공학
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• 제11권1호
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• pp.39-44
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• 1996

The pressure fluctuations in a gas-solid fluidized bed has been analysed using s statistical method interpreting fluidized 냥d behavior. The performing statistical a analysis of the pressure fluctuations in a fluidized bed of 6.7cm-ID. using uniform p particle size of 115 to $1015{\mu}m$ in diameter. The fluidized gas used air(velocity 0.1~1.2m/sec) at settled bed height to diameter ratios which is LlD=l.O. Then, the pressure fluctuations measured by DPT(differantial pressure transducer). The measuring characteristic values of pressure fluctuation were the mean value and standard value, and also, it has been found that the standard deviation of the pressure fluctuations can be effectively used to predict minimum fluidizing velocity and to explain the fluidized phenomena.

• 한국환경보건학회지
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• 제24권1호
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• pp.54-61
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• 1998

This study was conducted in order to evaluate the treatment efficiencies of anaerobic packed and fluidized-bed biofilm and to investigate applicability in treating livestock wastewater. Biocarbonate alkalinity(BA) and volatile fatty acid(VFA) were about 3,230-3,270 mg/l, 3,790-3,126 mg/l(as CaCO$_3$) and 224-402 mg/l, 141-387 mg/l(as CH$_3$COOH), and VFA/BA ratio was about 0.069~0.12, 0.045-0.12 in packed and fluidized-bed biofilm. When COD loading rate was 6.0 kg COD/$m^3\cdot$ day in packed and fluidized-bed biofilm, methane gas production were 3.23 l/day and 4.38 l/day, respectively. In the same COD loading rate, methane gas production volumes per kg COD removal were 0.25 m$^3$ CH$_4$/kg COD$_{rm}$ and $0.28 m^3 CH_4/kg COD^{rm}$, respectively. At this time, it could be estimated that fluidized-bed biofilm was more high. In case of HRT 0.94 day(6.0 kg COD/$m^3\cdot$ day) and 11 day(0.5 kg COD/$m^3\cdot$ day), packed-bed biofilm showed 59% and 81% COD removal efficiency, respectively. While fluidized-bed biofilm showed 72% and 85% removal efficiency, respectively. It was showed that fluidized-bed biofilm was more efficient. Packed-bed biofilm was higher than fluidized in treatment efficiencies of organic matters, but required continuous treatment using combined system, because it was very exceeded over an environmental standard solidified from '96 year. In operating fluidized-bed biofilm, if farm house consider high power cost according to high circulation ratio in an economic point of view, it would have an effect that farm house use packed-bed biofilm as combined system in treating livestock wastewater.

• 한국환경과학회지
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• 제5권1호
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• pp.93-102
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• 1996

Hydrodynamic characteristics such as gas holdup, liquid circulation velocity and bed expansion in a hexagonal inverse fluidized bed were investigated using air-water system by changing the ratio ($A_d$/$A_r$) of cross-sectional area between the riser and the downcomer, the liquid level($H_1$/H), and the superficial gas velocity($U_g$). The gas holdup and the liquid circulation velocity were steadily increased with the superficial gas velocity increasing, but at high superficial gas velocity, some of gas bubbles were carried over to a downcomer and circulated through the column. When the superficial gas velocity was high, the $A_d$/$A_r$ ratio in the range of 1 to 2.4 did not affect the liquid circulation velocity, but the maximum bed expansion was obtained at $A_d$/$A_r$ ratio of 1.25. The liquid circulation velocity was expressed as a model equation below with variables of the cross-sectional area ratio($A_d$/$A_r$) between riser to downcomer, the liquid level($H_1$/H), the superficial gas velocity($U_g$), the sparser height[(H-$H_s$)/H], and the draft Plate level($H_b$/H). $U_{ld}$ = 11.62U_g^{0.75}$${(\frac{H_1}{H})}^{10.30}$${(\frac{A_d}{A_r})}^{-0.52}$${(\frac({H-H_s}{H})}^{0.91}$${(\frac{H_b}{H})}^{0.13}$

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.337-345
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• 2012

To check effects of operating variables on reaction characteristics of WGS catalyst for SEWGS process, water gas shift reaction tests were carried out in a pressurized fluidized bed reactor using commercial WGS catalyst and sand(as a substitute for $CO_2$ absorbent) as bed materials. Simulated syngas(mixed with $N_2$) was used as a reactant gas. Operating temperature was $210^{\circ}C$ and operating pressure was 20 bar. WGS catalyst content, steam/CO ratio, gas velocity, and syngas concentration were considered as experimental variables. CO conversion increased as the catalyst content and steam/CO ratio increased. CO conversion at fluidized bed condition was higher than that of fixed bed condition. However, CO conversion were maintained almost same value within the fluidized bed condition. CO conversion decreased as the syngas concentration increased. The optimum operation condition was confirmed and long time water gas shift reaction test up to 24 hours at the optimum operating conditions was carried out.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.209-213
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• 2016

경유자동차의 질소산화물을 저감하기위한 원심유동층장치를 개발하기 위해, 가스분산판 내경 184mm, 폭 50mm의 원심유동층장치에서 평균입자직경 $26{\mu}m$, $32{\mu}m$의 Cu-ZSM-5 제오라이트 촉매를 유동입자로 사용하여 원심유동층의 유동특성을 조사한 결과, 원심유동층내의 기포직경은 거의 0.3~3.0mm의 작은 범위이며, 기포의 상승속도는 기포직경 및 가스속도와 상관없이 0.0~0.4m/s 정도이다. 또한 원심유동층에서 사용가능한 평균입자 직경은 $60{\mu}m$이며, 층내에서 기체와 고체의 접촉은 양호한 것으로 조사되었다.

• 한국연소학회지
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• 제13권2호
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• pp.23-32
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• 2008

Gasification characteristics in the fluidized bed reactor are essential for the design of a gasification furnace to optimize the operation condition. Moisture content of the solid fuel is one of the important factors to influence directly the gasification characteristics. So it is necessary to investigate the effect of moisture content of solid fuel in partial oxidation condition. Gasification characteristics are investigated with results from thermogravimetric analyzer and lab-scale fluidized bed reactor for wood and RDF samples along with changing moisture contents. Additionally lab-scale fluidized bed reactor was run continuously and gas concentrations at the exit were measured. It is observed that the rate of reaction in partial oxidation condition is between the results from the combustion environment and from the inert condition. Moisture content in a particle slows down the heating rate of a particle. So, reaction is delayed by the moisture content. However, RDF samples those are easy to break-up don't show the effect of moisture content. The result of continuous operation condition shows that proper moisture content promotes gasification because steam from the particles helps gasification of the solid fuel. A simulation to predict the syn-gas composition was conducted by the Aspen Plus process simulator. The cold gas efficiency of the experiment was compared with results from the simulation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.81-85
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• 2007

A fluidized bed reactor is made with quartz. The size of FBR is 0.055 m I.D. and 1.0 m in height. The FBR was employed for the thermocatalytic decomposition of propane to produce hydrogen without $CO_{2}$. The fluidized bed was proposed for the continuous withdraw of product carbons from the reactor. Carbon black DCC-N330 is used to decompose the propane gas. The propane decomposition reaction over carbon black catalyst in a fluidized bed reactor was carried out the temperature range of 600 ${\sim}$ 800 $^{\circ}C$, propane gas velocity of 1.0 ${\sim}$ 4.0$U_{mf}$($1U_{mf}$ = 0.61cm/s) and the catalyst loading of 100 ${\sim}$ 200g. Production of $H_{2}$ such as other reaction temperature, gas velocity, catalytic loading on the reaction rates was investigated. The carbon depositied on the catalyst surface was observed by FE-SEM. The particle size of the carbon black was observed by Particle size analyzer. Resulting production in the experiment was not only hydrogen but also several by-products such as methane, ethylene, ethane, and propylene.