Methaleurop weser Zink GmbH, Nordenham, Germany.
Biotechnol Bioeng. 1991 Jun 5;38(1):56-64. doi: 10.1002/bit.260380108.
The local properties of the dispersed gas phase (gasholdup, bubble diamater, and bubble velocity) were measured and evaluated at different positions in the riser and downcomer of a pilot plant reactor and, for comparison, in a laboratory reactor. These were described in Parts I and II of this series of articles during yeast cultivation and with model media. In the riser of the pilot plant reactor, the local gas holdup and bubble velocities varied only slightly in axial direction. The gas holdup increased considerably, while the bubble velocity increased only slightly with aeration rate. The bubble size diminished with increasing distance from the aerator in the riser, since the primary bubble size was larger than the equilibrium bubble size. In the downcomer, the mean bubble size was smaller than in the riser. The mean bubble size varied only slightly, the bubble velocity was accelerated, and the gas holdup decreased from top to bottom in the downcomer. In pilot plant at constant aeration rate, the properties of the dispersed phase were nearly constant during the batch cultivation, i.e., they depended only slightly on the cell concentration. In the laboratory reactor, the mean bubble sizes were much larger than in the pilot plant reactor. In the laboratory reactor, the bubble velocities in the riser and downcomer increased, and the mean gas holdup and bubble diameter in the downcomer remained constant as the aeration rate was increased.
在酵母培养和模型介质中，我们在中试工厂和实验室的反应器的上升段和下降段的不同位置测量和评估了分散气相（气体滞留量、气泡直径和气泡速度）的局部性质。这些性质在本系列文章的第一部分和第二部分中进行了描述。在中试工厂反应器的上升段中，局部气体滞留量和气泡速度在轴向方向上仅略有变化。随着通气速率的增加，气体滞留量显著增加，而气泡速度仅略有增加。由于初始气泡尺寸大于平衡气泡尺寸，因此在上升段中，从曝气器到上升段的距离增大，气泡尺寸减小。在下降段中，平均气泡尺寸小于上升段。平均气泡尺寸变化不大，气泡速度加快，气体滞留量从顶部到底部下降。在恒定通气速率的中试工厂中，在分批培养过程中，分散相的性质几乎保持不变，即它们仅略微取决于细胞浓度。在实验室反应器中，平均气泡尺寸比中试工厂反应器大得多。在实验室反应器中，随着通气速率的增加，上升段和下降段的气泡速度增加，而下降段的平均气体滞留量和气泡直径保持不变。
