双循环流化床提升管中气固流动特性及接触效率研究

以催化裂化平衡剂和常温空气为介质，在新型双循环流化床冷态模拟装置上，考察了单、双侧下料结构、双路循环颗粒循环速率比例对提升管内气固流动状态的影响，并提出了一种新的气固接触效率的定义。结果表明：单、双侧下料结构的不同对提升管内颗粒浓度的分布影响不大，其差异主要体现在提升管预提升区和底部反应区；双侧下料时的颗粒浓度径向分布均匀性明显优于单侧下料，且两路颗粒循环速率越接近，颗粒浓度径向分布越均匀，轴对称性越好，气固接触效率越高；降低表观气速或增大颗粒循环速率均有利于提高气固接触效率。

STUDY ON GAS-SOLID FLOW CHARACTERISTICS AND CONTACT EFFICIENCY IN DUAL-LOOP CIRCULATING FLUIDIZED BED RISER

Effects of feeding structures with solids from single or double sides and ratio of solids circulation rates from both sides on the gas-solids flow characteristics were investigated in a cold model apparatus of a novel dual-loop circulating fluidized bed, and a new definition of gas-solids contact efficiency was also proposed to evaluate the reactor. Results showed that the solids feeding methods had very little impact on the axial and radial distribution of solids concentration when the solids came down from one or two sides, and the differences mainly lay in the pre-lifting and bottom reaction zones of the riser. When two strands of solids were feeding bilaterally into the riser bottom together, the solids contribution presented a better radial distribution than that of only single strand of solids feeding, and closer solids circulating rates of the two loops would contribute to better radial uniformity and axial symmetry of solids concentration profiles with higher gas-solid contact efficiency. And higher gas-solids contact efficiency could be obtained when decreasing superficial gas velocity or increasing solids circulation rates.