Linek V, Moucha T, Dousová M, Sinkule J
Department of Chemical Engineering, Institute of Chemical Technology, 166 28 Prague 6, Czech Républic.
Biotechnol Bioeng. 1994 Mar 15;43(6):477-82. doi: 10.1002/bit.260430607.
The dynamic pressure method (DPM) is used for measurement of k(L)a in a 1-m(3) pilot scale fermentor in coalescing (distilled water) and noncoalescing (0.3 M Na(2)SO(4) aqueous solution) batches. The method consists in recording oxygen concentration in a batch after a small pressure change (20 kPa) in the fermentor. The upward pressure change is brought about by temporary closing and subsequent throttling of outlet gas stream and the downward change by full reopening of the gas outlet. Absorption of pure oxygen yields the same k(L)a values as absorption of air. In noncoalescing batch, the downward k(L)a values are always higher than the upward values owing to spontaneous nucleation of bubbles. The experiments performed in a stirred cell confirm this behavior. Thus, only upward pressure change should be used for measurement. The correlation of k(L)a data measured in small (18-L) and large (1000-L) vessels based on power dissipated and superficial gas velocity are in a good agreement. Unlike the DPM, the classical dynamic methods yield, under the same conditions, excessively low values of k(L)a (the dynamic startup method) or fail to produce data at all (the dynamic method with interchange of air for N(2)). (c) 1994 John Wiley & Sons, Inc.
动态压力法（DPM）用于在1立方米中试规模发酵罐中，对聚结（蒸馏水）和非聚结（0.3M硫酸钠水溶液）批次的k(L)a进行测量。该方法包括在发酵罐中进行小的压力变化（20kPa）后，记录批次中的氧气浓度。向上的压力变化是通过暂时关闭并随后节流出口气流来实现的，而向下的压力变化则是通过完全重新打开气体出口来实现的。纯氧的吸收产生的k(L)a值与空气吸收产生的相同。在非聚结批次中，由于气泡的自发成核，向下的k(L)a值总是高于向上的值。在搅拌池中进行的实验证实了这种行为。因此，仅应使用向上的压力变化进行测量。基于功率耗散和表观气体速度，在小型（18升）和大型（1000升）容器中测量的k(L)a数据的相关性非常吻合。与DPM不同，经典动态方法在相同条件下会产生过低的k(L)a值（动态启动法）或根本无法产生数据（空气与氮气互换的动态法）。（c）1994约翰·威利父子公司
