Attrition characteristics of iron ore by an air jet in gas-solid fluidized beds

Kang, Dong Hyun,Ko, Chang Kuk,Lee, Dong Hyun Elsevier 2017 Powder technology Vol.316 No.-

<P><B>Abstract</B></P> <P>The effects of superficial gas velocity (U<SUB>g</SUB> =1.25–3.00m/s) and distributor hole size (8.0–12.4mm) on the attrition rate of iron ore in a gas-solid fluidized bed with 0.076m ID×3.7m height with or without solid circulation have been determined. The particle density and the Sauter mean diameter of fresh iron ore were 3705kg/m<SUP>3</SUP> and 357μm, respectively. When the kinetic energy rate from the orifice was equal or >180J/s, we could determine an attrition rate trend by measuring the fractional mass of fine particle formation (under 500μm fraction) during 30min without solids circulation. In the experiments with solids circulation, the attrition rate was determined by measuring the fractional mass of fine particle formation (under 63μm fraction; variation of threshold size). The attrition rate increases with increasing kinetic energy rate from the orifice (180J/s<E<SUB>K</SUB> <608J/s). The kinetic energy rate from the orifice was calculated using the mass flow rate and orifice nozzle velocity. The correlation of the attrition rate with the kinetic energy rate from the orifice isΦ/N=0.1214E<SUB>K</SUB> −1.3587 above the jet length.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Threshold size of attrition fines was used to determine attrition rates. </LI> <LI> Experiments were conducted with or without solids circulation. </LI> <LI> Correlation of attrition rate with the kinetic energy rate was derived. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Effect of Frame Rates on Knee Kinetics during Landing and Cutting

이승훈,신충수 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.2

The analysis of knee kinematics and kinematics during high-risk movements associated with anterior cruciate ligament (ACL)injury is essential to studying the mechanism of ACL injury. Motion capture at low frame rates may not always detect the actual peak values during high-speed movements. However, the knee kinetic differences between various frame rate measurements during high-risk movements have not been reported. The purpose of this study was to investigate whether 3D knee kinetics would be measured differently between frame rates such as a high frame rate (1200 Hz), 400 Hz, 240 Hz and the popular low frame rate (120 Hz). Knee kinetics during a single-leg drop landing and side-step cutting under different frame rates were repeatedly measured and statistically compared. Peak knee valgus and tibial internal rotation moments measured at a popular low frame rate were significantly lower than those measured at the other frame rates of 400 Hz and 1200 Hz. The peak anterior and superior forces measured at the highest (1200 Hz) frame rate were significantly higher than those measured at any other frame rates. In addition, the variations in the peak kinetic values were significantly larger at the lowest frame rate capture and trended toward being smaller at the higher frame rates. In conclusion, significant differences in the knee kinetics between the frame rates suggest that the high frequency capturing increases the accuracy of the knee kinetics measurement for high risk maneuvers for the study of ACL injury.

Kinetic spray 공정으로 제조된 순수 알루미늄 코팅 소재의 변형률 속도에 따른 고속 압축 변형 거동

유지상(J. S. Yu),김규식(K. S. Kim),허훈(H. Huh),이기안(K. A. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10

The thickness directional compressive deformation behavior of kinetic sprayed pure aluminum layers was investigated. Using kinetic spray processes, 15-㎜ thick pure Al coating layers could be made. The strain rate effect on the mechanical properties and deformation behavior of pure aluminum coating layer were investigated by compression test (from 1 × 10?³/s to 1 × 10?¹/s) and Split-Hopkinson Pressure Bar (from 1.9 × 10³/s to 3.3 × 10³/s). In compression and SHPB tests, yield strength of kinetic sprayed pure aluminum increased from 200 ㎫ to 224 ㎫ with increasing strain rate. The strain rate sensitivity of kinetic sprayed pure aluminum material was 0.0118. Due to the initial severely deformed structure of the kinetic sprayed coating material, a strain softening phenomenon occurred after the yield point even at room temperature because of dynamic recovery, based on the results of the analysis. The production of high-strength metal bulk materials using kinetic spray processes was deemed possible.

Experimenting biochemical oxygen demand decay rates of Malaysian river water in a laboratory flume

Nuruzzaman,Abdullah Al-Mamun,Noor Bin Salleh 대한환경공학회 2018 Environmental Engineering Research Vol.23 No.1

Lack of information on the Biochemical Oxygen Demand (BOD) decay rates of river water under the tropical environment has triggered this study with an aim to fill the gap. Raw sewage, treated sewage, river water and tap water were mixed in different proportions to represent river water receiving varying amounts and types of wastewater and fed in a laboratory flume in batch mode. Water samples were recirculated in the flume for 30 h and BOD and Carbonaceous BOD (CBOD) concentrations were measured at least six times. Decay rates were obtained by fitting the measured data in the first order kinetic equation. After conducting 12 experiments, the range of BOD and CBOD decay rates were found to be 0.191 to 0.92 per day and 0.107 to 0.875 per day, respectively. Median decay rates were 0.344 and 0.258 per day for BOD and CBOD, respectively, which are slightly higher than the reported values in literatures. A relationship between CBOD decay rate and BOD decay rate is proposed as kCBOD = 0.8642kBOD - 0.0349 where, kCBOD is CBOD decay rate and kBOD is BOD decay rate. The equation can be useful to extrapolate either of the decay rates when any of the rates is unknown.

순산소 연소환경에서 촤-CO₂ 가스화 반응과 그 kinetic rate에 관한 이해

김대희(Daehee Kim),최상민(Sangmin Choi),Christopher R. Shaddix 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41

The purpose of this study is to recognize the necessity of char-CO₂ gasification reaction consideration on the oxy-coal combustion modeling and furthermore the appropriate high temperature kinetic rate. Char-CO₂ gasification studies in the literature were reviewed and it was concluded that char-CO₂ gasification reaction can contribute to the overall char burning rate, considering the elevated CO₂ level, possible lean O2 part in a boiler, real high operation temperature and the dependence of coal reactivity on CO₂ gas. The experimental method to derive the high temperature kinetic rate of CO₂ gasification reaction was presented to cover the uncertainty of previous kinetic data.

Insights from an OKMC simulation of dose rate effects on the irradiated microstructure of RPV model alloys

Li Jianyang,Zhang Chonghong,Martin-Bragado Ignacio,Yang Yitao,Wang Tieshan 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

This work studies the defect features in a dilute FeMnNi alloy by an Object Kinetic Monte Carlo (OKMC) model based on the "grey-alloy" method. The dose rate effect is studied at 573 K in a wide range of dose rates from 108 to 104 displacement per atom (dpa)/s and demonstrates that the density of defect clusters rises while the average size of defect clusters decreases with increasing dose rate. However, the dose-rate effect decreases with increasing irradiation dose. The model considered two realistic mechanisms for producing <100>-type self-interstitial atom (SIA) loops and gave reasonable production ratios compared with experimental results. Our simulation shows that the proportion of <100>-type SIA loops could change obviously with the dose rate, influencing hardening prediction for various dose rates irradiation. We also investigated ways to compensate for the dose rate effect. The simulation results verified that about a 100 K temperature shift at a high dose rate of 1 104 dpa/s could produce similar irradiation microstructures to a lower dose rate of 1 107 dpa/s irradiation, including matrix defects and deduced solute migration events. The work brings new insight into the OKMC modeling and the dose rate effect of the Fe-based alloys.

해수 조건에서 총암모니아성 질소 부하량과 수리학적 공기 부하량에 따른 유동상 여과조의 질산화 성능 평가

이재건,이영훈,박정환,Jaegeon Lee,Younghun Lee,Jeonghwan Park 한국수산과학회 2023 한국수산과학회지 Vol.56 No.6

The purpose of this study was to assess the efficiency of nitrification based on ammonia loading rates and hydraulic air-loading rates in a moving bed bioreactor (MBBR) under seawater conditions. The goal was to provide foundational data for the design of these bio reactors. At an ammonia loading rate of 0.2 g TAN·m^-2 surface area·day^-1, the influent TAN concentration was determined to be 1.76±0.33 mg·L^-1, which is below the safe concentration for fish survival (2 mg·L^-1). Considering operational aspects, the optimal ammonia-loading rate was derived. Subsequently, experimental results for nitrification efficiency at the optimal ammonia-loading rate revealed that the optimum hydraulic air-loading rate was 1.8 L·air·m^-2 surface area·min^-1. This condition resulted in the lowest concentrations of TAN and NO₂-N in the influent water, thus establishing the optimal hydraulic air-loading rate. A regression equation was derived for the ammonia-removal rate (Y) based on the ammonia-loading rate (x) and expressed as a 0.5-order equation (Y=ax^0.5+b). Specifically, for TAN concentrations of 0-6 mg·L-1, the regression equation Y=0.1683x^0.5-0.13628, was established.

Effect of ammonia on the kinetics of sulfur dioxide absorption into aqueous 2-amino-2-methyl-1-propanol solutions

Jeon, Soo-Bin,Cho, Joon-Hyung,Kang, Min-Kyoung,Lee, Sang-Sup,Kim, Bong-jun,Oh, Kwang-Joong Elsevier 2017 Journal of the Taiwan Institute of Chemical Engine Vol.81 No.-

<P><B>Abstract</B></P> <P>Rate constants for the reaction of aqueous 2-amino-2-methyl-1-propanol (AMP)/ammonia (NH<SUB>3</SUB>) solutions with SO<SUB>2</SUB> were determined by measuring their SO<SUB>2</SUB> absorption rates. The SO<SUB>2</SUB> absorption characteristics of 30 wt% AMP solutions with added NH<SUB>3</SUB>(1, 3, and 5 wt%) were investigated using a stirred-cell reactor, and the rates of SO<SUB>2</SUB> absorption into the aqueous blended amine solutions were measured. The addition of 5 wt% NH<SUB>3</SUB> to AMP significantly increases the SO<SUB>2</SUB> absorption rate, as well as the rate constant for the reaction of AMP with SO<SUB>2</SUB> by 197%. The relevant Arrhenius expressions were found to be <SUB> k A M P , S <SUB> O 2 </SUB> </SUB> = 50.787 × 1 <SUP> 0 7 </SUP> exp ( − 3880.47 / T ) , and <SUB> k A M P + N <SUB> H 3 </SUB> , S <SUB> O 2 </SUB> </SUB> = 377.168 × 1 <SUP> 0 7 </SUP> exp ( − 4283.71 / T ) .</P> <P><B>Highlights</B></P> <P> <UL> <LI> The SO<SUB>2</SUB> mass transfer resistance of liquid phase between 5 and 15 kPa was disregarded. </LI> <LI> The SO<SUB>2</SUB> absorption rate on each absorbent increased exponentially proportional to the NH<SUB>3</SUB> addition. </LI> <LI> The absorption rate of SO<SUB>2</SUB> increased exponentially along partial pressure increase at each temperature. </LI> <LI> The overall reaction of SO<SUB>2</SUB> with AMP/NH<SUB>3</SUB> solution is the instantaneous reaction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

스테인레스 용강내 질소 용해반응에 미치는 Ti 및 Nb의 영향

張民煥,洪仁國,朴鍾震,宋孝錫,李庸得 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.3

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500℃ using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting A1_20_3 on the melt surface. A small addition of CaO-Al_2O_3 synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate.

Influence parameters in the ozonation of phenol wastewater treatment using bubble column reactor under continuous circulation

Manickam Matheswaran,문일식 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.3

The ozonation of phenol wastewater treatment system has been investigated with effective mass transfer between gas and liquid phase in a bubble column reactor. The designed bubble column reactor was investigated for increasing the rate of mass transfer of ozone, the rate of oxidation of phenol in the solution, the solubility and decomposition rate of ozone in the distilled water were also studied at different flow rates. The decomposition rate constants were calculated based on pseudo first order kinetics. The oxidation of phenol was investigated in order to provide the overall reaction rate constant for the reaction between ozone and phenol at 25℃. The influence of the operating parameters like initial phenol concentration, ozone flow rate and pH for the destruction of phenol by ozonation were studied. The pseudo first order rate constant was depending on the initial concentration of phenol solution. A comparison of TOC removal percentage between bubble column reactor and bubble diffuser using ozonation were reported.