中文摘要：

对中心气升式气固环流反应器和自由床流化反应器的流动特性进行了对比.结果表明,在同样的操作条件下,在轴向高度h=112～512 mm范围内,环流反应器导流筒区的径向不均匀指数RNI比自由床的RNI减小27%～36%;与自由床相比,环流反应器导流筒区的局部不均匀指数减小20%～59%,整体不均匀指数减小17%～43%,环流反应器的流化质量较高;环流反应器导流筒区和自由床内均存在气体返混现象,导流筒区各采样点示踪气体的浓度和轴向扩散系数Da,g比自由床均有所降低,在表观气速0.2～0.4 m/s范围内,导流筒区Peclet准数的绝对值比自由床增大12%～58%,说明导流筒区气体返混程度小于自由床,气-固两相流向上的宏观流动可有效抑制气体的轴向返混.

英文摘要：

Flow characteristics were investigated and compared between a draft tube-lifted gas-solid air loop reactor （GSALR） and a free fluidized bed reactor （FFB） based on the same operating conditions. The results show that the radial heterogeneity index in the draft tube region of GSALR is smaller 27%-36% than that in FFB at axial height h=112-512 mm. The local heterogeneity index is smaller 20%-59% and the overall heterogeneity index is smaller 17%-43% in the draft tube region of GSALR than those in FFB. Compared with FFB, GSALR is superior in the fluidization quality. Gas back mixing characteristics were studied in GSALR and FFB, and the one-dimensional axial dispersion model was established. The tracer gas concentration and axial diffusion coefficient are smaller in the draft tube region of GSALR than those in FFB. The absolute value of Peclet number is smaller 12%~58% in FFB than that in the draft tube region of GSALR when the superficial gas velocity is 0.2-0.4 m/s, demonstrating that the gas back mixing is weaker in the region. The upward macro-flow in the draft tube region could effectively restrain the axial gas-back mixing.