Behavior of bubble formation in high pressure suspended bubble column

关于常压下孔口气泡形成的研究工作较多，而高压下的研究工作较少。本文通过实验测量了高压气泡柱和悬浮气泡柱中孔口处气泡的体积，并研究了系统压力、气体流量、孔口直径、气室体积和颗粒含率等因素对气泡形成的影响。从理论上考虑，提出了非球形气泡形成模型，并将计算结果与实验结果进行了比较。得到了以下结果：1。气泡体积随气体流量和孔直径的增大而增大，随系统压力和颗粒含率的减小而减小。非球形气泡形成模型的计算结果与实验结果具有相似的趋势。在高气体流速或高压区域，气室体积对气泡体积的影响可以忽略不计。这一结果也得到了气泡形成模型计算的支持。对于高压气泡柱或悬浮气泡柱的气泡形成装置的设计，为了增加有效界面面积，建议气泡形成条件接近于恒流条件，即无因次电容数N_C(=4V_C rho _Lg/ pi D_O ^2P_s) < 1。

Many works have been done about the bubble formation at an orifice under atmospheric pressure, while a few works have been done under high system pressure.In this work, the volumes of bubbles formed at an orifice in high pressure bubble column or suspended bubble column were measured experimentally and the effects of various factors on bubble formation, such as the system pressure, gas flow rate, orifice diameter, gas chamber volume and particle holdup were investigated. By the theoretical consideration, the non-spherical bubble formation model was proposed and the calculated results were compared with the experimental ones. The following results were obtained :1. The bubble volumes, increase with increases in gas flow rate and orifice diameter, and with decreases in system pressure and particle holdup. The calculated results by the non-spherical bubble formation model show the similar tendency with the experimental results.2. In high gas flow rate or high pressure regions, the effect of gas chamber volume on the bubble volume is negligible. This result is also supported by the bubble formation model calculation.For the design of bubble formation apparatus in high pressure bubble column or suspended bubble column, it is recommended the bubble formation condition to take close to the constant flow condition, which is written by the dimensionless capacitance number N_C(=4V_C rho _Lg/ pi D_O ^2P_s) < 1, owing to increase effective interfacial area.