ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Using of the Dynamic Pressure-Step Method for Mass Transfer Coefficient Measurement in the Internal-Loop Airlift Reactor

M. Blažej, J. Annus, and J. Markoš

Department of Chemical and Biochemical Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava

E-mail: markos@cvt.stuba.sk

Received: 1 April 2003

Abstract: The principle of the dynamic pressure-step method, consists insimultaneous measurement of both the oxygen concentration and the totalpressure in the internal-loop airlift reactor (ALR). After reaching steadyoxygen concentration in liquid (0.3 M-Na₂SO₄ solution) atthe atmospheric pressure, the pressure in the column was increased by about 15kPa. The pressure in the column changed in about 10-15 s, therefore this methodis called the non-ideal pressure-step method. Then, the instantaneous values ofboth the column pressure and the oxygen concentration could be used forcalculation of instantaneous driving force for the oxygen mass transfer withoutthe need of immediate pressure step.

Measurements were carried out in the ALRs with a working volume of 40 dm³. Pureoxygen, air, and 0.3 M-Na₂SO₄ aqueoussolution were used as the model gas and liquid media. Measurements showed verygood agreement between k _{L a} valuesmeasured with air and pure oxygen, respectively in the whole range of usedsuperficial velocities of input gas. Further experiments proved instantaneous changeof oxygen concentration in the whole volume of liquid phase. Measured data weredescribed by correlation based on superficial gas velocity of the input gas andby linear dependence on overall gas hold-up in the liquid.

Chemical Papers 57 (6) 445–450 (2003)