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Experiments of gas mixing between two half-beds were performed in a dual-leg circulating fluidized bed(DL-CFB)240 mm in width,40 mm in depth and 2000 mm in height by using glass beads with diameter of 0.25-0.28 mm as bed material.SO2 and CO as the gas tracers entering the left and right distributors separately were used to simulate the gas mixing between the two legs.MSD(mean square displacement)model was adopted to calculate the gas dispersion coefficient(Dw)which was used to investigate the effect of fluidization velocity and bed material inventory on gas mixing in the DL-CFB.The experimental results showed that Dw was about 50-300 cm2穝-1 at different fluidization velocities and bed material inventories.A higher fluidization velocity benefited particles exchange between two half-beds,which intensified the gas-solids interactions at the region with higher solids volume fraction.The gas mixing in the lower region of the DL-CFB was stronger than that in the upper region of the bed.A higher bed inventory was helpful to gas mixing at a lower fluidization velocity,while a higher fluidization velocity weakened gas mixing because of higher solids concentration in the center of the bed that prevented gas mixing. 相似文献
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双支腿流化床压力脉动的递归分析 总被引:1,自引:0,他引:1
采用递归图系统研究了流化风速、床存量对双支腿流化床(DL-FB)内气固流动混沌特性的影响规律。DL-FB的宽、深和高分别为0.24、0.04和2.0 m,支腿高为0.16 m,使用粒径范围为0.25~0.28的玻璃珠作为床料。结果表明递归图可用于描述DL-FB内的气固两相流动的混沌特性,且DL-FB内的气固流动较单布风板流化床复杂。DL-FB系统熵随着流化气速的增加呈"M"型曲线变化。DL-FB系统随气速的增加会出现低速颗粒未交换段、低速颗粒交换起始段、颗粒交换段和颗粒悬浮段。床存量对系统熵的影响较大且没有明显规律。DL-FB内的压力脉动包含气泡行为和颗粒交换在半床间交换行为。 相似文献
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引入混沌特征参数关联维数(D2)和柯尔莫哥洛夫熵(Kolmogorov entropy,KE),结合颗粒交换瞬时分布图,系统研究了流化风速、床存量对双支腿流化床颗粒在支腿间的混合交换特性及其影响规律。结果表明,双支腿流化床内颗粒在支腿间的交换具有混沌特性。D2和KE均可以表征支腿间颗粒混合交换行为。D2和KE均随着气速的增加先减小后增加,系统混沌程度先减弱后增强;D2和KE随着床料高度的增加均增加。支腿间颗粒交换方式包括单颗粒交换和颗粒团簇交换,颗粒团簇交换方式会促进系统D2和KE增加,促使系统更混沌。 相似文献
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双支腿流化床颗粒交换的压力信号分析 总被引:1,自引:0,他引:1
为研究双支腿流化床支腿间颗粒交换特性,采用粒径为0.9~1min的玻璃珠为床料,在尺寸为240mm×20mm×800mm的二维有机玻璃可视化双支腿流化床内,采集差压脉动信号对床内差压进行了功率谱密度及香农熵的分析,研究了颗粒在支腿间的质量交换、流化风速和床存量对颗粒交换的影响,以及颗粒交换行为的稳定性规律。研究结果表明,支腿间颗粒交换方式以颗粒团簇和单颗粒为主,分别对应第一主频和第二主频。流化风速的增加使2种颗粒交换方式所占的比重趋于相等,床存量的增加会加剧颗粒在支腿间的质量交换。流化风速和床存量的增加使两主频相互靠近。颗粒交换行为的稳定性和确定性随着气速的增加先增强后逐渐减弱。 相似文献
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