Rate of Oxygen Absorption by Aqueous Sodium Sulfite Solution in Gas-Liquid Fluidized Beds

Abstract

The rate of oxygen absorption by aqueous sodium sulfite solution containing cupric ion as a catalyst was measured, using a gas-liquid fluidized bed as shown in Fig. 1 and Table 1.The results obtained are as follows:1) Flow patterns can be roughly classified into three kinds according to the velocity of the gas flow:-(a) the streamline region, where the gas holdup, (1-ψ), increases linearly with the increase in velocity of the gas flow;(b) the foam bed or transition region, where (1-ψ) becomes maximum; and (c) the turbulent region, where (1-ψ) is nearly constant.2) The gas holdup is a function of the velocity of gas flow, hole diameter and clear liquid height (L0) when L0 is smaller than 30cm, but it is nearly independent of the clear liquid height when L0 is larger than 30cm.3) Pressure drop required for generating gas bubbles on the plate is expressed by Eq.(2)(Cf. Fig. 3).4) The rate of oxygen absorption by aqueous sodium sulfite solution is independent of cupric ion concentration, and is apparently of zero-order, with respect to the sulfite ion concentration under the experimental conditions.5) The value of KGa' is closely related to the value of (1-ψ)/ψ, and is proportional to L0-1/3 when L0 is smaller than 30cm (Cf. Fig. 6).6) In the streamline region, KGa is a function of uG and d, and is independent of n and L0, but in the foam bed region, it is influenced by L0 (Cf. Figs. 7-10).7) The experimental equation (Eq.(12)) has been obtained for calculating the value of KG in the temperature range from 10 to 22°C (Cf. Figs. 5 and 11).8) The rate of oxygen absorption is controlled by the liquid-side resistance.9) In the foam bed and the turbulent regions, the mean contact area per unit volume of bed, a, as calculated from Eqs.(10) and (12) is found to be in the region between 600-1000m2/m3.