共查询到19条相似文献,搜索用时 140 毫秒
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通过酒糟在流化床干燥器上的冷态实验,得出全床压降随气流速度、料层厚度、物料初始湿含量及气体分布板开孔率的变化规律,经整理数据得出相关参数之间的准则关联式。 相似文献
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通过对1 060t/h裤衩腿型循环流化床锅炉的大量变工况试验,获得了不同负荷率下的炉内压力分布,给出了该锅炉稀相区物料质量浓度的分布规律,并分析了流化风速和床压降对物料质量浓度分布的影响,得到物料质量浓度随流化风速和炉膛高度变化的关系式以及物料质量浓度随床压降和炉膛高度变化的关系式.结果表明:在床压降不变的条件下,流化风速与炉内平均物料质量浓度成正比;在流化风速不变的条件下,在一定的范围内,床压降与炉内平均物料质量浓度成正比,当床压降升高到某一临界值后,床压降与炉内平均物料质量浓度成反比. 相似文献
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循环流化床(CFB)锅炉炉膛物料浓度分布直接影响炉膛内的传热特性和锅炉负荷。基于CFB锅炉炉膛内气固两相流动特性,建立了密相区以上区域的物料浓度数学计算模型。以1台1 060 t/h CFB锅炉为研究对象,数值计算分析不同煤种、给煤粒度分布、流化风速、分离器效率及床压降对炉膛物料浓度分布的影响,计算分析结果表明,CFB锅炉运行中,针对不同煤质,可以通过优化给煤粒度分布和床压降来调节炉膛上部的物料浓度分布,低挥发分煤种的给煤粒度分布中细颗粒的比例要大一些。分离器性能越好,床质量越好,在相同的流化风速和床压降下,炉膛出口处物料浓度随d50、d99的减小而增大。 相似文献
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为了从理论基础上研究带风帽的旋流喷动流化床干燥器内气固两相流流动特性,采用欧拉多相流模型对一台旋流喷动流化床试验台进行三维数值模拟,分析了各种不同底部进风速度V底与切向进风速度V切比例对旋流喷动流化床干燥器内的气体速度分布和颗粒速度分布特性的影响,以及当V底/V切为30 m·s-1/30 m·s-1时,探讨了气固流动状态随时间的变化规律。研究结果表明:增大V切,有利于增加近壁面区域的气体流动速度和促进气固相的充分混合,增加气体和颗粒相的接触面积,有利于减少气相流动死区,降低黏性物料对筒体壁面的粘附程度。但由于切向风的卷吸作用所形成的负压会导致轴向气流减弱,不利于筒体中心区域气流的轴向发展,降低了轴向风对颗粒层的穿透效果。 相似文献
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ABSTRACTSupercritical water fluidized bed reactor is a promising in the clean and efficient conversion of coal, and the distributor is one of the key component for the heat and mass transfer enhancement. However, the optimization study for the distributor in supercritical water fluidized bed reactor has been seldom conducted due to the special thermal properties of supercritical water. In this work, the swirling flow distributor was designed for its optimization for heat and mass transfer inside a supercritical water fluidized bed reactor. The swirling flow can be generated by the concentric circle or triangle type hole distribution in distributor with 0 or 45° intersection angle between the fluid inlet velocity direction and the distributor plane. The computational particle fluid dynamics (SCWFB) method, which has quick calculating speed and high accuracy, was used in this work to study the particle-fluid two-phase flow behaviors inside SCWFB with swirling flow distributors. Investigations were made to reveal the influence of the hole distribution type and intersection angle on the bed pressure drop and particle volume fraction characteristics. The results showed that the triangle type distributor with 45° intersection angle has the best fluidization performance. The conclusions drawn may has potential application for continuous and stable operation of supercritical water fluidized bed reactor for coal gasification. 相似文献
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外加磁场对磁流化床烟气脱硫过程的影响 总被引:1,自引:0,他引:1
研究了磁流化床脱硫过程中外加磁场对流化状态、脱硫效率和脱硫产物特性的影响,并分析了磁场强化脱硫的机理.结果表明:随着磁场的增强,磁流化床经历了3个阶段.在鼓泡流化状态下,床层压降不稳定,脱硫效率低;在磁稳流化状态下,床层压降小,脱硫效率快速提高;在磁聚状态下,床层压降较大,脱硫效率提高.兼顾脱硫效率和能源消耗两方面的要求,在磁稳流化状态下进行烟气脱硫是适宜的.此外,对脱硫产物微观形貌和化合物成分的分析表明:磁场改变了铁磁颗粒表面脱硫产物的附着方式,并促进了S(IV)的氧化,提高了SO2的吸收速率,从而提高了磁流化床的脱硫效率. 相似文献
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在双支腿循环流化床冷态试验台上进行了床料平衡试验,得到不同流化参数下风量和床压的动态曲线,基于并行流道阻力特性分析,提出双支腿炉膛翻床条件的预测方法,并模拟了控制逻辑对翻床的控制效果.结果表明:当流化风量大于临界翻床风量时,双支腿炉膛处于自平衡区,两侧炉膛的流化风量和床压的瞬时偏差能够相互纠正,两侧床料处于动态平衡;当流化风量小于临界翻床风量时,将发生翻床现象;临界翻床风量随着静止床料高度的增加而减小;采用调整风门开度的方法解决翻床问题存在局限性,床料平衡的首要策略是使双支腿系统处于自平衡状态运行. 相似文献
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A transducer pressure probe is devised to measure the pressure‐history curves up to a maximum frequency of 200 Hz. It is installed on the wall of a 153 mm2 fluidized bed and is employed to establish the solids mixing and movement pattern of an air fluidized bed comprising of glass beads of 2093 μm average diameter. The pressure variations recorded with a speed of about 11 Hz for a period of 92 s are employed to compute several statistical functions and analysed to infer the quality of fluidization. For the range of fluidization number 1.05–1.48, it is inferred that in this bubbling regime, the solids near the bed wall region descend down while the air bubbles drift to the central region and rise up in the fluidized bed. This bulk macroscopic hydrodynamic picture of solids movement is in conformity with the conclusions of other co‐workers. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Akira Nishimura Seiichi Deguchi Hitoki Matsuda Masanobu Hasatani Arun S. Mujumdar 《亚洲传热研究》2002,31(4):307-319
A pulsating fluidized bed is operated with two sequential durations designated as an on‐period with injecting fluidization gas and an off‐period without it. The heat transfer coefficient between a vertically immersed heater and bed in a pulsating fluidized bed is measured under various pulse cycles and fluidized particles. The obtained results are compared with those in a normal fluidized bed with continuous fluidization air injection. The relationship between heat transfer coefficients and bubble characteristics, evaluated using a digital video camera, has also been investigated. For certain fluidized particles and operating pulse cycles, the fluidization of particles and the increment of heat transfer coefficients can be obtained under a mean air velocity based on a pulse cycle duration smaller than the minimum fluidization air velocity in a normal fluidized bed. Under the pulse cycles where a static bed through the whole bed is formed in the off‐period duration, the improved heat transfer rate over that in a normal fluidized bed can be measured. This may be attributed to large bubble formation. As heat transfer in the pulsating fluidized bed is obstructed with increasing time to keep a static bed due to the excessive off‐period duration, it is indicated that there is an optimum off‐period duration based on the heat transfer rate. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(4): 307–319, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10038 相似文献