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首页> 外文会议>World Congress on Particle Technology >The voidage in a CFB riser as function of solids flux and gas velocity
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The voidage in a CFB riser as function of solids flux and gas velocity

机译：CFB立管中的空隙作为固体通量和气体速度的函数

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Circulating Fluidised Beds (CFBs) are widely applied in the process industry, for mostly gas-solid and gas-catalytic reactions. The riser is the key component of the CFB being the process reactor. The important design parameters are the operating gas velocity (U) and the solids concentration flux (G). The CFB operation starts at moderate to high superficial gas velocities. Its voidage exceeds ～ 0.9 and is a function of the solids circulation flux. Different flow modes have been presented in literature, and result in an operation diagram where G and U delineate specific operations, from dilute riser flow, through core-annulus flow, to dense riser upflow (mostly at any U, G exceeding 80 to 120 kg m~(-2)s~(-1)). Increasing G whilst maintaining the gas velocity will cause an increase in suspension concentration. The riser flow can hence be characterized by its apparent voidage, ε. In the core-annulus operation, clusters of particles reflux near the wall, thus influencing the local radial voidage in the cross section of the riser, and also extending over a given distance, 8, from the wall to the core . Through measurements in CFBs of 0.1 and 0.14 m I.D., the research has been able to determine the average axial and radial voidages of the dense phase within the different regimes, whilst also determining the thickness of the annulus (in CAF-mode). Experimental results will be illustrated and compared with previous empirical equations, shown to have a limited accuracy only both for e, and for the thickness of the annulus in CAF operation. Within the operating conditions tested, results demonstrate that the annulus thickness is about 15 to 20% of the riser diameter in CAF, and that the voidage in the riser is a function of U and G, with riser diameter and distance along the riser length as secondary parameters.
机译：循环流化床（CFB）广泛应用于工艺业，主要是气固和气体催化反应。提升管是CFB是过程反应器的关键组成部分。重要的设计参数是操作气体速度（U）和固体浓度通量（G）。 CFB操作以中度至高浅表气体速度开始。其空隙超过〜0.9，是固体循环通量的函数。已经在文献中呈现不同的流动模式，并导致操作图，其中G和U描绘特定操作，从稀释提升管流来，通过核心环流量，以致密的立管溢出（主要是在任何U，G超过80至120kg。 m〜（-2）s〜（-1））。保持气体速度的增加率增加将导致悬浮浓度的增加。因此，提升管流动的特征在于其明显的空隙ε。在核心环操作中，在壁附近的粒子回流簇，从而影响提升器的横截面中的局部径向空隙，并且还从给定距离8，从壁到芯延伸。通过CFB中的测量值0.1和0.14 m I.D。，该研究已经能够确定不同方案内的致密相的平均轴向和径向空隙，同时确定环的厚度（在CAF模式下）。将示出实验结果并与先前的经验方程进行比较，所示仅具有有限的精度，仅为E，以及CAF操作中环的厚度。在测试的操作条件下，结果表明，环厚度为CAF中提升管直径的约15％至20％，并且提升管中的空隙是U和G的函数，提升器直径和沿提升管长度的距离和沿提升管长度的函数。次要参数。

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