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首页> 外文学位 >Application of a reflective optical probe to measure solids fractions in a circulating fluidized bed.
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Application of a reflective optical probe to measure solids fractions in a circulating fluidized bed.

机译：反射式光学探针在循环流化床中测量固体含量的应用。

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A novel method of extracting localized solids volume fractions from reflective multi-fiber optical probes was developed. The fiber optic probes were originally designed by Vector Scientific, Inc. to measure local solids velocities. The probe measures reflected light from a particle medium which is converted into a voltage. Development of this new method yields two valuable solid flow parameters from a single probe system. The method involves a formulated model with empirical calibrations and three physical bases. The three physical bases are the Conservation Law, Beer-Lambert's Law, and the reflected light intensity from the particle medium. A novel bed depth calibration procedure is used to find the reflected light contribution from each layer of particles. This calibration is used to find the fixed fraction, k1, of scattered light detected by the probe, and the factor, k2, to convert number concentration into a solids volume fraction. The layer-by-layer analysis of the solids fraction avoids the need to directly address the effects of beam divergence and multiple scattering.; The probes were used to measure the solids volume fractions and velocities inside the riser of a cold-flow Circulating Fluidized Bed (CFB) operating under several different flow conditions. These experiments were performed with two different batches of glass spheres, with average particle diameters of 64 mum and 180 mum, respectively. The solids fraction measurement method was compared with other solids fraction measurement methods. The fiber optic probe method compared well with other methods including solids sampling and pressure drop measurements, with the exception of near wall measurements using a solids sampling probe. The fiber optic probe gave solids fractions varying from 1.0% to 3.1% near the center and 7.7% and 21.1% at the wall of the riser of the CFBC, which is consistent with other solids fraction measurement methods.; The fiber optic probe was used to make measurements at different angular positions near the solids inlet, in the fully developed region, and near the solids outlet of the CFB riser. The method developed allowed calculation of the solids fraction distribution at these locations. Statistical analyses were performed in order to determine if the velocities or solids fractions were azimuthally dependent. It was found that the angular dependency of solids velocity and solids fractions is functions of elevation and flow conditions.
机译：开发了一种从反射式多光纤光学探针中提取局部固体体积分数的新方法。光纤探头最初是由Vector Scientific，Inc.设计的，用于测量局部固体速度。探针测量来自颗粒介质的反射光，该反射光被转换为电压。这种新方法的开发可从单个探针系统产生两个有价值的固体流参数。该方法涉及具有经验校准和三个物理基础的公式化模型。这三个物理基础是守恒定律，比尔-朗伯定律和粒子介质的反射光强度。一种新颖的床层深度校准程序可用于发现每一层颗粒的反射光贡献。该校准用于查找探针检测到的散射光的固定分数k1和因子k2，以将数字浓度转换为固体体积分数。固体成分的逐层分析避免了直接解决光束发散和多重散射的影响的需求。探针用于测量在几种不同流动条件下运行的冷流循环流化床（CFB）提升管内部的固体体积分数和速度。这些实验是用两批不同的玻璃球进行的，平均粒径分别为64微米和180微米。将固体分率测量方法与其他固体分率测量方法进行了比较。光纤探针法与其他方法（包括固体采样和压降测量）进行了很好的比较，但使用固体采样探针进行的近壁测量除外。光纤探头给出的固体分数在中心附近为1.0％至3.1％，在CFBC立管壁处为7.7％和21.1％，与其他固体分数测量方法一致。光纤探头用于在CFB立管的固体入口附近，完全展开区域和固体出口附近的不同角度位置进行测量。开发的方法允许计算这些位置处的固体分数分布。为了确定速度或固体分数是否与方位角有关，进行了统计分析。发现固体速度和固体分数的角度依赖性是高程和流动条件的函数。

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