循环流化床脱硫反应器流场特性实验研究

Experimental Study on the Flow Field Characteristics in the Circulating Fluidized Bed Desulfurization Reactor

在φ250 mm×9000 mm循环流化床实验装置上,研究了循环流化床的压力和颗粒浓度在不同操作条件下的分布规律,并采用径向不均匀指数(RNI)对颗粒浓度径向分布的不均匀性沿轴向的变化进行了定量描述。试验结果表明,循环流化床中循环回路压力平衡曲线呈"8"字型分布,主床压差主要集中在文丘里段,与回料口在文丘里扩张段相比,文丘里压差所占比例有所减小,文丘里压差在相似操作条件下的变化与主床一致。循环流化床床内颗粒浓度随固体颗粒循环流率的增大或表观气速的减小而增大,径向颗粒浓度呈典型的"中心稀边壁浓"的环-核结构,循环流化床径向平均浓度随着提升管高度的增加先减小后增大,截面平均颗粒浓度沿轴向呈"C"型分布。固体颗粒浓度径向分布的不均匀性沿轴向先增大后减小,并与截面平均颗粒浓度存在很强的关联性。

Distribution law of pressure drop and particle concentration of circulating fluidized bed was studied under different operating conditions in a circulating fluidized bed experimental device with the diameter of 250mm and the height of 9000 mm and a radial non-uniformity index（ RNI） was applied to describe quantitatively the non-uniformity in radial distribution of solid particle concentration along the axial. The results show that pressure balance curve of the whole loop takes the shape of ＂ 8＂ in circulating fluidized bed. The bed pressure drop mainly concentrates in the venturi,compared to return solids stream position in venturi expansion,the proportion of venturi pressure drop reduces. Changes of pressure drop in venturi are consistent with the main bed in the similar operating conditions. In the circulating fluidized bed particle concentration increases with increasing of solids circulating flow rate or decrease of superficial gas velocity,the radial particle concentration is a typical core-annulus pattern with a dilute center and a concentrated wall,radial average concentration in circulating fluidized bed increase and then decrease with increase of riser height,distribution of section average particle concentration is the ＂ C＂ type along the axial. The radial non-uniformity of solid particle concentration increases firstly and then decreases up the riser,and correlate strongly with cross-sectional average solid particle concentration. The results give a good guidance to the design and optimization of the circulating fluidized bed desulfurization reactor.