Noise analysis of transmitted light beams for determining bubble velocity and gas holdup profiles in a bubble column

Noise analysis techniques are used to construct bubble velocity and gas holdup profiles in an air/water bubble column. It is shown that the use of laser renders reliable and consistent results. A comparison with local data obtained with a four-point glasfiber probe and the drift flux model of Barnea and Mizrahi is made. The velocity profiles become steeper with increasing height in the column and with increasing gas flow rate. The holdup profiles are rather flat. The measurements are performed in a 50 mm inner-diameter tube and cover a holdup range from 2 % to 12 %.