Analysis of the effect of uncertainties in hydrodynamic parameters on the accuracy of the gas flow modulation technique for bubble columns

Abstract

The gas flow modulation technique has recently been proposed as a novel method for determining the axial gas dispersion coefficient in bubble columns. The approach is based on a marginal sinusoidal modulation of the gas inlet flow rate that acts as a virtual tracer. Axial gas dispersion is then inversely calculated from amplitude damping and phase shift via an analytical solution of the axial dispersion model. The proposed study provides an analysis of the inherent uncertainties related to the assumptions of constant axial gas dispersion coefficient and bubble rise velocity, which are crucial for implementing the method. Besides, the sensitivity of the approach is assessed as a function of the modulation parameters, the bubble rise velocity and the axial gas dispersion coefficient. Eventually, the possibility of tailoring the modulation parameters depending on the expected value of the axial gas dispersion coefficient to increase the sensitivity and to reduce the uncertainty is also assessed.