To reduce sulfur oxide emissions of ocean-going vessels, exhaust gas cleaning systems are installed in many instances. Initially, these plants were mainly designed as spray scrubbers, but the use of packed scrubbers offers potential for process optimization due to more compact
design. This dissertation is dedicated to the development and validation of a mass transfer model to describe the separation of SO2 in seawater using packed scrubbers.
To model the separation of SO2 in seawater, liquid phase chemical reactions are consolidated into a simplified reaction system for the calculation of SO2 equilibrium molality in seawater. Based on this, the separation of SO2 from the gas phase into the scrubbing liquid is calculated via axial discretization of the investigated column packings. The volumetric mass transfer coefficients (kGa and kLa) of the examined column packings serve as essential model parameters.
Suitable measurement methods for column packing kGa and kLa values are implemented. Determination of kGa is performed by absorption of SO2 in NaOH, determination of kLa is performed by desorption of CO2 from water. Comparability between obtained measurement data with results previously acquired by other research groups is shown. Experimental validation of the mass transfer model is performed through measuring the separation of SO2 into synthetic seawater. For this, 5 structured packings and 1 random packing are investigated using two experimental plants (inner diameters 150 and 422 mm). Model predictions for SO2 separation efficiency are in very good agreement with measurement data. Mean and maximum deviations are −0.97%/12.14% (150 mm column) and −2.77%−16.01 % (422 mm column). This corresponds to only a minimal underestimation of model predictions for SO2 removal efficiency compared to measured data. Finally, the now validated model is used to investigate processes occurring inside the packing during absorption of SO2 into seawater and to identify the main factors influencing the separation of SO2 into seawater.