• 제목/요약/키워드: Solid height

검색결과 272건 처리시간 0.023초

Effects of Operating Variables on the Solid Circulation Rate in a Three-phase Circulating Fluidized Bed

  • Kim, Min Kon;Hong, Sung Kyu;Lim, Dae Ho;Yoo, Dong Jun;Kang, Yong
    • Korean Chemical Engineering Research
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    • 제53권4호
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    • pp.440-444
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    • 2015
  • Effects of operating variables on the solid circulation rate were investigated in a three-phase circulating fluidized bed, of which inside diameter was 0.102m and height was 3.5m, respectively. Gas velocity, primary and secondary liquid velocities, particle size and height of solid particles piled up in the solid recycle device were chosen as operating variables. The solid circulation rate increased with increasing primary and secondary liquid velocities and height of solid particles piled up in the solid recycle device, but decreased with increasing particle size. The value of solid circulation rate decreased only slightly with increasing gas velocity in the riser. The values of solid circulation rate were well correlated in terms of dimensionless groups within the experimental conditions.

높이차가 존재하는 두 분류의 2상유동에 관한 연구 (Study on Two-Phase Flow generated by Two Jets with Height Difference)

  • 박상규;양희천;이용호
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권1호
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    • pp.88-93
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    • 2000
  • In this study, the mixing process of two-phase flow generated by two jets with height difference is analyzed. The primary jet is jetted on the condition of the state mixed pulverized solid particles with air. The height difference between the main jet and the secondary jet is changed into three kinds(0, 32.5, 47.5mm). The velocity vector field, concentration field and turbulent properties of solid particles are measured by using 3-Dimensional Particles Dynamics Analyzer. As the height difference of two jets through the two nozzles increases, the solid particle recirculation zone and the dense zone in the combustion chamber become large. The solid particle concentration at the center of the combustion chamber gets dense because the particle velocity remains slow due to the existence of the solid particle recirculation zone. The particle concentration in the combustion chamber can also be influenced by the hight difference of two jets.

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Analysis of Electrical Properties of Ti/Pt/Au Schottky Contacts on (n)GaAs Formed by Electron Beam Deposition and RF Sputtering

  • Sehgal, B-K;Balakrishnan, V-R;R Gulati;Tewari, S-P
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제3권1호
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    • pp.1-12
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    • 2003
  • This paper describes a study on the abnormal behavior of the electrical characteristics of the (n)GaAs/Ti/Pt/Au Schottky contacts prepared by the two techniques of electron beam deposition and rf sputtering and after an annealing treatment. The samples were characterized by I-V and C-V measurements carried out over the temperature range of 150 - 350 K both in the as prepared state and after a 300 C, 30 min. anneal step. The variation of ideality factor with forward bias, the variation of ideality factor and barrier height with temperature and the difference between the capacitance barrier and current barrier show the presence of a thin interfacial oxide layer along with barrier height inhomogenieties at the metal/semiconductor interface. This barrier height inhomogeneity model also explains the lower barrier height for the sputtered samples to be due to the presence of low barrier height patches produced because of high plasma energy. After the annealing step the contacts prepared by electron beam have the highest typical current barrier height of 0.85 eV and capacitance barrier height of 0.86 eV whereas those prepared by sputtering (at the highest power studied) have the lowest typical current barrier height of 0.67 eV and capacitance barrier height of 0.78 eV.

2탑 유동층 시스템에서 선택적 고체순환을 위한 고체분리기 개발 (Development of Solid Separator for Selective Solid Circulation in Two-interconnected Fluidized Beds System)

  • 류호정;박영철;이승용;김홍기
    • Korean Chemical Engineering Research
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    • 제47권2호
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    • pp.195-202
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    • 2009
  • 선택적 고체순환이 가능한 2탑 유동층 공정 개발을 위한 기초연구로 금속 망이 장착된 입자크기분리 시스템에 의해 입자크기 차이를 이용하여 고운입자와 굵은입자를 분리할 수 있는 고체분리기를 개발하였으며 고체분리속도에 미치는 유속, 고체분리기의 설치높이 및 분리면적의 영향을 측정 및 고찰하였다. 고체분리기에 의한 고체분리속도는 기체유속, 고체분리기의 설치높이, 분리면적이 증가함에 따라 증가하였다. 기체유속 및 고체분리기 설치높이 증가에 따른 고체분리속도의 변화경향은 기포크기의 변화경향과 유사하였다. 본 연구에서 개발한 고체분리기를 이용하여 굵은입자($212{\sim}300{\mu}m$)와 고운입자($63{\sim}106{\mu}m$)의 분리가 가능하였으며 고체분리속도는 4.4~127 g/min의 범위를 나타내었다. 개발된 고체분리기를 회수증진 수성가스변환 공정에 적용하여 선택적 고체순환이 가능한 2탑 유동층 공정구성을 제안하였다.

Impact of Screw Type on Kyphotic Deformity Correction after Spine Fracture Fixation: Cannulated versus Solid Pedicle Screw

  • Arbash, Mahmood Ali;Parambathkandi, Ashik Mohsin;Baco, Abdul Moeen;Alhammoud, Abduljabbar
    • Asian Spine Journal
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    • 제12권6호
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    • pp.1053-1059
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    • 2018
  • Study Design: Retrospective review. Purpose: To detect the effect of cannulated (poly-axial head) and solid (mono-axial head) screws on the local kyphotic angle, vertebral body height, and superior and inferior angles between the screw and the rod in the surgical management of thoracolumbar fractures. Overview of Literature: Biomechanics studies showed that the ultimate load, yield strength, and cycles to failure were significantly lower with cannulated (poly-axial head) pedicle comparing to solid core (mono-axial head). Methods: The medical charts of patients with thoracolumbar fractures who underwent pedicle screw fixation with cannulated or solid pedicle screws were retrospectively reviewed; the subjects were followed up from January 2011 to December 2015. Results: Total 178 patients (average age, $36.1{\pm}12.4years$; men, 142 [84.3%]; women, 28 [15.7%]) with thoracolumbar fractures who underwent surgery and were followed up at Hamad Medical Corporation were classified, based on the screw type as those with cannulated screws and those with solid screws. The most commonly affected level was L1, followed by L2 and D12. Surgical correction of the local kyphotic angle was significantly different in the groups; however, there was no significant difference in the loss of correction of the local kyphotic angle of the groups. Surgical correction of the reduction in the vertebral body height showed statistical significance, while the average loss of correction in the reduction of the vertebral body height was not significantly different. The measurement of the angles made by the screws on the rods was not significantly different between the cannulated (poly-axial head) and solid (mono-axial head) screw groups. Conclusions: Solid screws were superior in terms of providing increased correction of the kyphotic angle and height of the fractured vertebra than the cannulated screws; however, no difference was noted between the screws in the maintenance of the superior and inferior angles of the screw with the rod.

측면가열 자연대류 밀폐공간에서 고체 삽입물이 열성층화에 미치는 영향 (Effect of a Solid Insert on Thermal Stratification in a Side-Heated Natural Convection Enclosure)

  • 김수현
    • 설비공학논문집
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    • 제16권3호
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    • pp.211-217
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    • 2004
  • Effect of a solid insert on thermal stratification in the natural convection enclosure is numerically investigated. The enclosure consists of two differently heated vertical walls and two adiabatic horizontal walls. A solid insert is located in the middle of the enclosure. The non-dimensional governing equations are solved by using the SIMPLER algorithm. The computations are carried out with the variations of thermal conductivity, width and height of the solid insert. The Prandtl number of the fluid in an enclosure is fixed at Pr=0.71, Two cases of Rayleigh number are considered in the present study, i.e., Ra:10$^3$ and 10$^{6}$ . The thermal stratification attenuates as thermal conductivity, width, and height of the solid insert are increased. As the thermal conductivity ratio of a solid insert to fluid increases beyond (equation omitted)10$^3$, the thermal stratification ratio shows an asymptotic value.

레이저 빔에 의해 생성된 금속액적의 충돌거동 (Collision Behavior of Molten Metal Droplet by Laser Beam)

  • 김용욱;양영수
    • 한국레이저가공학회지
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    • 제6권1호
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    • pp.1-8
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    • 2003
  • A molten metal droplets are deposited onto solid substrate for solid freeform fabrication, Collision dynamic and substrate heat transfer associated with solidification determine the final shape of molten metal droplets. In this study, the experimental model, based on the variational condition with substrate temperature and falling height, was produced reliable optimal data of droplet pattern.

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고체연료 매체순환연소기를 위한 회재분리기에서 분리속도 및 분리효율에 미치는 조업변수들의 영향 (Effects of Operating Variables on Separation Rate and Separation Efficiency in Ash Separator for Solid Fuel Chemical Looping Combustor)

  • 류호정;이동호;윤주영;장명수;배달희;박재현;백점인
    • 한국수소및신에너지학회논문집
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    • 제27권2호
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    • pp.211-219
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    • 2016
  • To develop an ash separator for the solid fuel chemical looping combustion system, effects of operating variables such as solid injection nozzle velocity, diameter of solid injection nozzle, gap between solid injection line and vent line, vent line inside diameter, and solid intake height on solid separation rate and solid separation efficiency were measured and discussed using heavy and coarse particle and light and fine particles mixture as bed material in an acrylic fluidized bed apparatus. The solid separation rate increased as the solid injection nozzle velocity and the diameter of solid injection nozzle increased. However, the solid separation rate decreased as the gap between solid injection line and vent line, the vent line inside diameter, and the solid intake height increased. The solid separation efficiency was in inverse proportion to the solid separation rate. In this study, we could get high solid separation rate up to 2.39 kg/hr with 91.6% of solid separation efficiency.

탈기에 의한 심층포기 호기조 MLSS (Mixed Liquor Suspended Solid) 침전성 향상 방안 연구 (Study to enhance the settleability of deep aeration tank MLSS (Mixed Liquor Suspended Solid) by air sparging)

  • 한지수;이제승;이병희
    • 상하수도학회지
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    • 제38권3호
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    • pp.165-175
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    • 2024
  • The dissolved air at the bottom layer of the deep aeration tank transforms into fine gas bubbles within the MLSS (Mixed Liquor Suspended Solid) floc when exposed to the atmosphere. MLSS floc flotation occurs when MLSS from the deep aeration tank enters the secondary clarifier for solid-liquid separation, as dissolved air becomes fine air within the MLSS floc. The floated MLSS floc causes a high SS (Suspended Solid) concentration in the secondary effluent. The fine air bubbles within the MLSS floc must be removed to achieve stable sedimentation in the secondary clarifier. Fine bubbles within the MLSS floc can be removed by air sparging. The settleability of MLSS was measured by sludge volume indexes (SVIs) after air sparging MLSS taken at the end of the deep aeration tank. MLSS settling tests were performed at MLSS heights of 200, 300, 400, and 500 mm, and compressed air was fed at the bottom of the settling column with air flow rates of 100, 300, and 500 ml/min at each MLSS height, respectively. Also, at each height and air flow rate, air was sparged for 3, 5, and 7 minutes, respectively. SVI was determined for each height, air flow rate, and sparging time, respectively. Experimental results showed that a 300 mm MLSS height, 300 ml/min air flow rate, and 3 minutes of sparging time were the least conditions to achieve less than 120 ml/g of SVI, which was the criterion for good MLSS settling in the secondary clarifier.

케미컬루핑 연소시스템을 위한 산소전달입자의 상온-상압 고체순환특성 (Solid Circulation Characteristics of Oxygen Carrier for Chemical Looping Combustion System at Ambient Temperature and Pressure)

  • 윤주영;김하나;김정환;이도연;백점인;류호정
    • 한국수소및신에너지학회논문집
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    • 제28권4호
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    • pp.384-391
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    • 2017
  • Effects of operating variables on solid circulation rate were measured and discussed using two-interconnected circulating fluidized bed system at ambient temperature and pressure. OCN 706-1100 particles were used as oxygen carrier. The measured solid circulation rates increased as the lower loop seal gas flow rates and the solid height in the fuel reactor increased. Suitable operating conditions to avoid choking of the air reactor were confirmed. Continuous long-term operations of steady-state solid circulation were also demonstrated at two different conditions based on the operating window.