石油焦燃烧器环流混合段内床层的轴向密度分布

Axial Distributions of Solids Density in Annular Flow Mixing Unit of Combustor for Petroleum Coke

采用气-固环流反应器与输送床烧焦管相结合的结构形式,建立了一套适应石油焦或气化余焦燃烧要求的大型冷态实验装置.在不同操作条件下,采用差压变送器测定了环流混合段内环区及外环区内床层轴向压力梯度及密度的分布规律.结果表明,内环床层密度分布可分为底部密相区和上部湍流扩散区;内环颗粒循环强度对底部密相区的密度分布影响较小,只对导流筒上部湍流扩散区有影响;随着内环表观气速的增大,整个内环床层密度均降低.外环床层密度分布与内环的表观气速、颗粒循环强度和外环床层密相料位高度有关.利用实验数据回归出了内环和外环轴向颗粒密度分布的经验模型,其计算值与实验值吻合较好.

A large-scale cold experimental equipment which can adapt to combustion demands of petroleum coke was established by using the combined structure of gas-solid annular flow and riser transporter reactor. The pressure gradients of air-sand two-phase flow along the axial direction of the annular flow unit were measured by differential pressure transmitters under different operation conditions. The axial distributions of solids density in two regions of the annular flow mixing unit, namely internal annular and external annular regions, were investigated. The results show that the axial distributions of solids density in the internal annular region have two modes, namely the bottom dense phase and the upper turbulent flow diffusion phase. The solids flux has little effect on the density distributions in the bottom dense region, but significant effect on the upper turbulent flow diffusion region. The solids density in the whole internal annular region decreases with increasing the superficial gas velocity. The axial distribution of solids density in the external annular region is directly relative to the superficial gas velocity, solids flux in the internal annular region and the solids dense phase level in the external annular region. The empirical models for axial distributions of solids density in the internal and external annular regions have been established based on the experimental data. The model predictions are in good agreement with the experimental data.