共查询到20条相似文献,搜索用时 0 毫秒
1.
Satoru Matsuda 《Powder Technology》2008,187(2):200-204
A method using an optical mouse sensor was developed to monitor the moving velocity of a solid mass. Calibration was carried out using a rotating plate. Results clarified that the developed method is useful to monitor the velocity up to some limit (v < 0.3 m/s), which depends on the optical mouse sensor used. A solid circulation rate in a circulating fluidized bed (CFB) was measured using this method. Results obtained using this method show agreement with those of visual observations. 相似文献
2.
在循环流化床(CFB)煤燃烧/热解双反应器冷态实验装置上,以硅胶和电厂锅炉灰为实验物料,考察了立管内的气固流动特性,其中立管的内径44mm、高3m。研究结果表明,立管内的气固流动形态为移动床流动,Leung的立管流动模型适合对该系统中立管内移动床流动的描述,经拟合分别得到了立管内气、同速率以及气同相对速率与固体速率之间的经验方程,对热态实验过程中判断立管内的气固流动型态以及料封的稳定性均具有一定的参考价值。 相似文献
3.
This paper focuses on the determination of the solids circulation of a CFB gasification system with a dual fluidized bed concept, and the distribution of the solid hold up under different fluidization conditions. A mathematical model of the riser was designed and implemented in a model of a dual fluidized bed system. This model contains routines for calculation of each section of the dual fluidized bed system. The behaviour of the system was analysed regarding changes in solid inventory and variations of geometry. A diagram is presented which allows an illustration of the influence of changes in the dual fluidized bed system configuration on the resulting stable operation points. Analysis concerning the effect of counter pressure on the combustion and gasification side confirms the role of the seal loop in stabilizing the operation of the gasification system. 相似文献
4.
A method is described to independently estimate the solids velocity and voidage in the moving bed portion of the NETL circulating fluidized bed (CFB). These quantities are used by a device that continuously measures the solids circulation rate. The device is based on the use of a rotating Spiral vane installed in the standpipe of a circulating fluid bed (CFB). Correlations were developed from transient experiments and steady state mass balance data to correct the solids velocity and solids fraction in the standpipe as a function of standpipe aeration rate. A set of statistically-designed experiments was used to establish the need for these corrections and to verify the accuracy of solid circulation rate measurements after correction. The differences between the original and corrected measurements were quantitatively compared. 相似文献
5.
Solid circulation characteristics in an internally circulating fluidized bed with orifice-type draft tube 总被引:1,自引:0,他引:1
Sang Done Kim Yo Han Kim Seon Ah Roh Dong Hyun Lee 《Korean Journal of Chemical Engineering》2002,19(5):911-916
Effects of superficial gas velocities to a draft tube, to an annulus section and particle size on the solid circulation rate
(G,) have been determined in an internally circulating fluidized bed (0.28 m I.D. × 2m high) with an orifice type draft tube.
The solid circulation rate from the draft tube to an annulus section increases with increasing gas velocities to the draft
tube(U
d
) and annulus section (Ua) and consequent increase in pressure drop across the orifice (ΔPor). However, the values ofG
s
decrease by 7–21% with increasing particle size from 86 to 288 μm. The pressure drop across the orifice increases with increasingU
d
andU
a
. However, ΔPor decreases by 5–23% with increasing particle size. To predictG
s
in an internally circulating fluidized bed, a correlation is proposed as a function of ΔPor
This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement Korea University. 相似文献
6.
7.
Hiroyuki Kage Ryuhei Abe Ryusuke Hattanda Tao Zhou Hironao Ogura Yoshizo Matsuno 《Powder Technology》2003,130(1-3):203-210
Circulating fluidized bed was proposed to be used as a coater, and coating experiments of glass beads with silica powder were performed in a circulating fluidized bed. Glass beads and silica powder were chosen as model particles, because their shape was almost spherical. The respective effects of gas flow rates supplied from a distributor and from an air nozzle for solid circulation, feed rate of powder suspension and particle content in the bed on coating efficiency and agglomeration are mainly discussed. Coating efficiency in circulating fluidized bed coater was correlated well with solid circulation time rather than with gas flow rates or solid circulation rate, while the agglomeration among core particles was mainly governed by solid circulation rate. 相似文献
8.
More and more CFB boilers with large capacity and ultra-tall furnaces are used for power generation. Understanding the fluid dynamics in the ultra-tall furnace is important. However, existing studies on fluid dynamics in the CFB furnace are limited to the risers with rather short height. An experimental study was conducted with a cold CFB test rig of 240 mm in I.D. and 38 m and 54 m in height respectively. The influences of total solid inventory Iv, and fluidizing gas velocity Ug on the axial voidage profile along the riser and solid circulation rate Gs were investigated. Experimental results showed that when Ug exceeded the transport velocity, an S-shaped voidage profile characterized by fast fluidization was established in the riser. In such circumstance, the voidage at top dilute section kept constant and Gs reached saturation carrying capacity (Gs = Gs?) and inappreciably change with riser height and Iv. Moreover, Gs? increased from 40 kg to 50 kg when the riser height increased from 38 m to 54 m. The results indicated that even for the 600 MWe supercritical CFB boiler with a 54 m tall furnace, only a modest increase of Iv and power of forced draft fans is needed to obtain high enough Gs to meet the requirements of heating surfaces arrangement in furnace and the circulation loop. The necessary conditions to form the S-shaped profile of voidage in the riser were also discussed. 相似文献
9.
通过对PDA测得的不同条件下的轴向场的分析,提出了水力旋流器内固相颗料向速度场的新的分析概念。并对测得的数据进行计算机拟合,得出了各区域内颗粒轴向速度的计算公式,为固相颗粒运动轨迹的计算提供了依据。 相似文献
10.
Sung Won Kim Jung Yeul Ahn Dong Hyun Lee Sang Done Kim 《Korean Journal of Chemical Engineering》2001,18(4):555-560
A modified impact probe for continuous measurement of solids circulation rate in a circulating fluidized bed has been developed based on a principle similar to a momentum probe. The response curves of solid flow from the probe have been characterized and calibrated in a test column (0.05 m-I.D.x0.80 m-high). The probe was validated in situ in the downcomer of a circulating fluidized bed (0.10 m-I.D.x4.80 m-high). The solid circulation rates obtained by the modified impact probe well agree with the measured solids circulation rate by the descent time method. Presented at the Int’/Sym. on Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University. 相似文献
11.
根据粘附性颗粒在流化过程中形成的聚团具有较宽粒径分布并因此导致大聚团在流化床中沉积和死床的问题,提出了循环流化床的锥形回料系统设计. 该回料系统包括两部分:锥形料腿和带辅助进气的V型阀. 实验证明,锥形料腿通过提供变化的表观流化气速,克服了流化聚团沉积死床等现象;而V型阀的辅助进气,对于保证V型阀顺利输送粘附性颗粒具有关键性作用. 借助这种回料系统,实现了高粘附性超细CaCO3颗粒在循环流化床的稳定快速流化. 从提升管内部拍摄的照片显示,尽管提升管采用较高的流化气体速度,但超细CaCO3颗粒仍然是以聚团的形式被流化. 对在提升管不同高度采集的聚团分析表明,处于快速流化状态的CaCO3聚团的直径远小于传统流化床中聚团的直径,并且在提升管高度方向聚团直径没有较大的变化. 同时实验还显示,提升管轴向空隙率呈S型分布,而径向则体现环-核结构,具有典型的快速床特征. 相似文献
12.
Hong-Sik Ahn Woon-Jae Lee Sang-Done KimDg Byung-Ho Song 《Korean Journal of Chemical Engineering》1999,16(5):618-623
The effects of orifice diameter in the draft tube, particle size, gas velocities and bed height on the circulation rate of
solids and gas bypassing between the draft tube and annulus have been determined in an internally circulating fluidized bed
(i.d., 0.3 m ; height, 2.5 m) with an orifice-type draft tube. A conical shape gas separator has been employed above the draft
tube to facilitate the separation of gases from the two beds. The circulation rate of solids and the quantity of gas bypass
from the annulus to draft tube show their minimums when the static bed height is around the bottom of the separator. The circulation
rate of solids increases with an increase in orifice diameter in the draft tube. At fixed aeration to the annulus, gas bypassing
from the draft tube to annulus sections decreases, whereas reverse gas bypassing from the annulus to the draft tube increases
with increasing the inlet gas velocity to the draft tube. The obtained solids circulation rate has been correlated by a relationship
developed for the cocurrent flow of gas and solid through the orifice. 相似文献
13.
本文提出了循环流化床锅炉炉膛的轴向压力及固体浓度分布的计算式。当给出表观气、循环固体流率以及颗粒性质时,可准确地预测炉膛压降与轴向固体浓度分布,为炉膛设计提供了计算依据。 相似文献
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15.
针对茂名石化煤代油技改项目2×410t/h CFB锅炉调试运行过程中出现的一系列问题,经过分析及计算,提出解决方法并取得了较好效果,为两台CFB锅炉实现长周期安全稳定运行打下了良好基础。 相似文献
16.
新开发的有机玻璃制成的旋流气升式环流反应器高为2m、内径75mm,内部的导流筒(材料为PVC)高1.5m、内径30mm、壁厚1mm且装有10组扇形翅片。以空气-水为两相物系、空气-水-K树脂为三相物系,常温常压下,利用直接取样法和压差法测量了上升区局部的气含率、固含率,研究了不同底部间隙、不同固体装填体积分数下表观气速和轴向高度对上升区气含率、固含率的影响规律。结果表明:在均匀鼓泡流时上升区气含率随着表观气速的增大而增大,随着固体装载量的增加而下降;在非均匀鼓泡流时,三相物系的气含率高于两相物系的气含率。随着上升区轴向高度的增大,上升区局部气含率变化不大;底部间隙越大,气含率越小。在轴向高度较低时上升区固含率随着轴向高度的增大而减小,轴向高度较高时上升区固含率基本保持不变。 相似文献
17.
分析了循环流化床锅炉受热面磨损的原因,介绍了采取的相应防磨措施。采取防磨措施后,提高了锅炉运行的可靠性,取得了良好的经济效益。 相似文献
18.
Xueyao Wang 《Fuel Processing Technology》2010,91(8):927-4458
In this paper, an experimental study is performed to investigate the flow structure in a circulating fluidized bed (CFB). The typical core-annulus structure and small amount of back-mixing of particles near the wall of the riser were observed. The axial solid concentration distributions contain a dilute region towards the up-middle zone and a dense region near the bottom and the top exit zones. Furthermore, the solid concentration decreases with the increase of the superficial gas velocity, and increases with the increment of the circulation rate at the same height position. The total pressure drop of the main bed represents a linear relationship with the solid flux rate. In the dense phase zone, the solid concentration increases linearly with the augmentation of the solid flux, however, the change of the solid concentration is slight, even unchangeable at the up zones. In addition, based on the Energy-Minimization Multi-Scale (EMMS) method, a revised drag force model is proposed, which is coupled in the Eulerian two-fluid model for simulating the flow structure in the riser. Numerical results are consistent with the experimental data, which indicate the revised drag force model is very successful in simulating flow structure of the dense gas-solid two-phase flow. 相似文献
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20.
《Journal of the European Ceramic Society》2022,42(7):3264-3270
The gas tightness of glass sealing materials is a big challenge for the solid oxide fuel cell (SOFC) stacks operating at high temperature. Thermal, sintering, crystallization behavior and gas tightness properties of the glass-based with two different Al2O3 contents sealants are evaluated and discussed. The study showed that the sealants avoid cracks at the interface on NiO-YSZ (NiO-yttria stabilized zirconia) and SUS430 stainless steel interconnect substrates. The Al2O3 embedded in the glass matrix as a second phase, and promoted crystallization of K[AlSi3O8] at the early stage. This may because some ultrafine Al2O3 particles whose structure is destroyed by prolonged high temperature treatment according XRD and TEM analysis. Especially, the sealant containing 5 wt% Al2O3 undergoes a thermal cycle and maintains a stable leakage rate below 10?4 sccm?cm?1 for about 1000 h at 750 °C. The above results prove the possibility of using the Al2O3-doped sealing glass for SOFC stacks. 相似文献