LIQUID-MIXING IN A BUBBLE COLUMN UNDER PRESSURE

The liquid axial-dispersion coefficient and gas hold-up are measured in a batch-type bubble column of 0.158 m diameter for the system water-nitrogen at pressures between 0.1 and 1.5 MPa. It is determined that pressure has a marked influence on ps hold-up (in accordance with the results in previous articles), whereas for the same conditions the influence of pressure on the liquid axial-dispersion coefficient is relatively small. Furthermore, it is noted that the influence of pressure on liquid mixing is opposite to what is predicted by theoretical equations for liquid mixing. On the basis of simple mechanistic arguments, these discrepancies are explained. Finally, it is also demonstrated that empirical equations based on atmospheric data can be used (with some adjustment) to estimate the liquid dispersion coefficient at higher pressures.