• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.871-877
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• 2018

Storing the surplus energy from renewable energy resource is one of the challenges related to intermittent and fluctuating nature of renewable energy electricity production. $CO_2$ methanation is well known reaction that as a renewable energy storage system. $CO_2$ methanation requires a catalyst to be active at relatively low temperatures ($250-500^{\circ}C$) and selectivity towards methane. In this study, the catalytic performance test was conducted using a pressurized bubbling fluidized bed reactor (Diameter: 0.025 m and Height: 0.35 m) with $Ni/{\gamma}-Al_2O_3$ (Ni70%, and ${\gamma}-Al_2O_3$30%) catalyst. The range of the reaction conditions were $H_2/CO_2$ mole ratio range of 4.0-6.0, temperature of $300-420^{\circ}C$, pressure of 1-9 bar, and gas velocity ($U_0/U_{mf}$) of 1-5. As the $H_2/CO_2$ mole ratio, temperature and pressure increased, $CO_2$ conversion increases at the experimental temperature range. However, $CO_2$ conversion decreases with increasing gas velocity due to poor mixing characteristics in the fluidized bed. The maximum $CO_2$ conversion of 99.6% was obtained with the operating condition as follows; $H_2/CO_2$ ratio of 5, temperature of $400^{\circ}C$, pressure of 9 bar, and $U_0/U_{mf}$ of 1.4-3.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.623-634
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• 2014

This study examined a feasibility of coagulation as post-treatment to remove sulfide and phosphorus for the effluent of anaerobic fluidized bed reactor (AFBR) treating domestic wastewater. Removal efficiencies of sulfide, phosphorus and COD by coagulation were not affected by pH in the range of 5.9 to 7.2. Alkalinity requirement could be estimated by the amount of $Fe^{3+}$ to form $Fe(OH)_{3(S)}$ and to remove sulfide and phosphorus. At coagulant aid dosage of 2 mg/L, anionic polymer showed best results regarding size and settleability of flocs. Sulfide removal for the AFBR effluent at the $Fe^{3+}/S^{2-}$ ratio of 0.64, close to the theoretical value of 0.67 found with a synthetic wastewater, was only 75.2%. One of the reasons for this high $Fe^{3+}/S^{2-}$ ratio requirement is that the AFBR effluent contains sulfide, phosphorus, hydroxide and bicarbonate which can react with $Fe^{3+}$ competitively. Concentrations of sulfide and phosphorous reduced to below 0.1 and 0.5 mg/L, respectively, at the $Fe^{3+}/S^{2-}$ ratio of 2.0. Average effluent COD of 80 mg/L, mostly soluble COD, was obtained at the dosage 50 mg $Fe^{3+}/L$ ($Fe^{3+}/S^{2-}$ ratio of 2.0) with corresponding COD removal of 55%. For better removal of COD, soluble COD removal at the AFBR should be enhanced. Coagulation with $Fe^{3+}$ removed sulfide, phosphorus and COD simultaneously in the AFBR effluent, and thus could be an alternative process for the conventional wastewater treatment processes where relatively high quality effluent is not required.

• Resources Recycling
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• v.19 no.2
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• pp.45-53
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• 2010

During the biomass gasification, tar generation is typically accompanied, which causes many problems, such as pipe plugging and equipment fouling. In the experiments, activated carbon was applied to the upper reactor of the two-stage gasifier in order to remove the tar generated during gasification. In addition, the effects of the upper-reactor temperature and equivalence ratio on the producer gas characteristics (composition, tar content and lower heating value) were investigated. To investigate the effect of the upper reactor-temperature, experiments were performed at 743, 793, $838^{\circ}C$, respectively. To examine the influence of the equivalence ratio, a comparison experiment was carried out at a equivalence ratio of 0.17. In all experiments, tar contents in the producer gases were below $2mg/Nm^3$. The maximum LHV of the producer gas was above $10MJ/Nm^3$, which is much higher than the typical LHV($3\sim6MJ/Nm^3$) in the air gasification of biomass.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.129-136
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• 2011

Simulated Moving Bed(SMB) process consists of multiple chromatographic columns, which are usually partitioned into four zones. Such a process characteristic allows a continuous binary separations those are impracticable in conventional batch chromatographic processes. Compared with batch chromatography, SMB has advantages of continuity, high purity and productivity. Various researches have been reported for the integration of reaction and recovery during process operation on the purpose of economics and effectiveness. Simulated Moving Bed Reactor(SMBR) is introduced to combine SMB as a continuous separation process and reactor. Several cases of SMBR have been reported for diverse reactions with catalytic, enzymatic and chemical reaction on ion exchange resin as main streams. With an early type of fixed bed using catalyst, SMBR has been developed as SMB using fluidized enzyme, SMB with immobilized enzyme and SMB with discrete reaction region. For simple modeling and optimization of SMBR, a method considering convection only is possible. A complex method considering axial dispersion and mass transfer resistance is needed to explain the real behavior of solutes in SMBR. By combining reaction and separation, SMBR has benefits of lower installation cost by minimizing equipment use, higher purity and yield by avoiding the equilibrium restriction in case of reversible reaction.

• Resources Recycling
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• v.17 no.6
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• pp.50-56
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• 2008

A polypropylene fraction collected from the stream of post-consumer plastics was pyrolyzed. The aim of this study is to observe the dependence of yield of BTEX-aromatics normally used as solvent on the reaction temperature. To reach the goal, three experiments were carried out at different temperature between 650 and $700^{\circ}C$, using a fluidized bed reactor that shows an excellent heat transfer. In the experiments, product gases were used as a fluidizing medium to maximize the amount of BTEX-aromatics at fixed flow rate and feed rate during the pyrolysis. Oil, gas and char were obtained as product fractions. Product gases were analyzed with GCs(TCD, FID) and with a GC-MS system for qualitative analysis. For an accurate analysis of product oil, the product oil was distilled under vacuum, and separated the distillation residues from oil fractions that were actually analyzed with a GC-MS system. As the reaction temperature went higher, the content of BTEX-aromatics increased. The maximal yield of BTEX-aromatics was obtained at $695^{\circ}C$ with a value of about 30%. The main compounds of product gas were $CH_4$, $C_2H_4$, $C_2H_6$, $C_3H_6$, $C_4H_{10}$ and the product gas had an higher heating value about 45MJ/kg. It could be used as a heat source for a pyrolysis plant or for other fuel applications.

• Clean Technology
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• v.20 no.3
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• pp.321-329
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• 2014

In this study, Indonesia low rank coal, which has moisture content of around 26%, is dried less than 5% by using a laboratory-scale (batch type) steam fluidized-bed dryer in order to produce the low-moisture, high rank coal. Normally, CCS (carbon capture and storage) process discharges $CO_2$ and steam mixture gas around $100-150^{\circ}C$ of temperature after regeneration reactor. The final purpose of this research is to dry low rank coal by using the outlet gas of CCS process. At this stage, steam is used as heat source for drying through the heat exchanger and $CO_2$ is used as fluidizing gas to the dryer. The experimental variables were the steam flow rate ranging from 0.3 to 1.1 kg/hr, steam temperature ranging from 100 to $130^{\circ}C$, and bed height ranging from 9 to 25 cm. The characteristics of the coal, before and after drying, were analyzed by a proximate analysis, the heating value analysis and particle size analysis. In summary, the drying rate of low rank coal was increased as steam flow rate and steam temperature increased and increased as bed height decreased.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.83-94
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• 2016

Performance of absorbent for post-combustion $CO_2$ capture was measured and discussed. Fully saturated fresh absorbent (P2-15F) and absorbents sampled from absorption and regeneration reactor of continuous $CO_2$ capture process, P2-15A, P2-15R, respectively, were used as representative absorbents. Small scale fluidized bed reactor (0.05 m I.D., 0.8 m high) which can measure exhaust gas concentration and weight change simultaneously was used to analyze regeneration characteristics for those absorbents. Exhausted moles of $CO_2$ and $H_2O$ were measured with increasing temperature. $H_2O/CO$ ratio and working capacity were determined and discussed to confirm reason of reactivity decay after continuous operation. Moreover, possibility of side reaction was checked based on the $H_2O/CO_2$ mole ratio. Finally, suitable regeneration temperature range was confirmed based on the trend of working capacity with temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.102.1-102.1
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• 2010

바이오매스(Biomass)는 지구상에서 에너지원으로 이용될 수 있는 모든 식물과 미생물을 총칭하는 의미로 사용된다. 최근 바이오매스를 에너지자원화 시키는 방법으로 주목받는 열화학적 전환(Thermo-chemical conversion) 반응은 산소가 없이 혹은 희박한 조건에서 바이오매스에 열과 압력을 가하거나 공기나 수증기 등의 가스화제와 반응하여 바이오오일(Bio-oil) 및 합성가스(Syngas)로 변화하는 프로세스를 의미한다. 바이오매스로부터 바이오 DME(Di-Methyl Ether) 생산을 위한 합성가스를 제조하기 위해서 국내 산림자원을 대상으로 열분해반응 특성연구를 수행하였다. 또한 이들 물질로부터 바이오 DME 합성을 위해 최적의 합성가스 제조를 위한 타당성 연구를 수행하였다. 반응온도 $800{\sim}900^{\circ}C$에서 가스화 수율은 78~80%, 촤 수율은 17~20%, 타르 수율은 4~10%였고, 합성가스($H_2$/CO)비는 0.9~1.6였다.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.798-806
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• 1993

In this study we developed the synthesis of high purity tungsten oxide from tungsten chlorides obtained by the chlorination of scheelite in a fluidized bed reactor. Within a minute of dissolution time, tungsten chlorides were almost dissolved in $H_2O_2$ solution. The proper dissolution conditions for the tungsten chlorides were as follows : $H_2O_2$ concentration 0.5%, dissolution temperature $15^{\circ}C$ and $H_2O_2$ amount to 0.5g tungsten chlorides 30ml. Under above conditions, the tungsten oxide prepared from dissolved product was identified as $WO_3$ and the purity of $WO_3$ was 99.53%.

• Journal of Powder Materials
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• v.19 no.6
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• pp.398-404
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• 2012

This paper describes the spherical ammonium diuranate gel particles which are the intermediated material of the $UO_2$ microsphere for an VHTR(very high temperature reactor) nuclear fuel. The characteristics of the intermediate-ADU gel particles prepared by AWD(ageing, washing, and drying) and FB(fluidized-bed) apparatus were examined and compared in a sol-gel fabrication process. The electrical conductivity of washing filtrate from the FB treating and the surface area of dried-ADU gel particles were higher than those of AWD treating. Also, an internal pore volume in dried-ADU gel particles showed a more decrease in AWD treatment than FB treatment because of decomposition of PVA affected by the washing time. However, the internal microstructures of ADU gel particles were similar regardless of the process variation.