MASS TRANSFER IN THE BIOREACTOR DURING GAS DISPERSION FROM THE STIRRER VORTEX CAVITY

Abstract

Gas-liquid bioreactors in which the introduction of the gas substrate in the culture liquid is carried out from the vortex cavity formed by the rotation of the stirrer.  In order to simplify the design and intensify mass transfer a new method of dispersing the gas substrate from the vortex cavity is proposed and studied.  It consists in maintaining local zones with reduced pressure in the liquid behind the rotating paddles and creating the necessary conditions for the introduction of the gas substrate. On the basis of numerical simulation the pressure is calculated and the zones of low pressure in liquid behind the stirrer paddles are determined. The value of differential pressure necessary for gas dispersion has been estimated. The angular velocity of liquid rotation depending on the number of partitions on the apparatus wall and the number of mixer revolutions is presented. The gas content in the liquid during the implementation of the investigated method has been determined. The average surface diameter of gas bubbles and interfacial surface of gas-liquid medium were calculated from experimental data. The power spent on stirring in the apparatus has been established and the power criterion with regard to gas content has been determined. Mass transfer at intensive gas dispersion from gas vortex cavity into liquid has been investigated. Criterion dependence for calculation of mass transfer coefficient is presented, taking into account energy dissipation spent on mixing and interfacial surface. The fields of application of bioreactor with new method of gas dispersion are shown.