The effects of changes in the geometry of a spinning cone distillation column (SCC) on the device capacity and mass-transfer performance have been explored using a two-phase liquid-gas computational fluid dynamics (CFD) model. Contributions of the inner and the outer liquid sprays to the volumetric mass-transfer coefficient have been separately analysed. With the increase in fluid flow rate, the mass transfer from the inner spray is predicted to rise proportionally (pre-loading regime), then pass through a maximum and decline (loading regime). The variation is associated with the changing position of the inner spray in the throat, with the maximum in mass transfer corresponding to the largest extent of the spray. The mass transfer rate from the outer spray is predicted to increase linearly with the flow rate in both the pre-loading and the loading regimes. The position and the extent of the outer spray are predicted to be almost unaffected by the intensity of the gas flow. The limit of the column capacity, in terms of the maximum flow rate attained at the threshold of flooding, rises in proportion to the inner throat area. For a given SCC design, the optimal value of a throat opening parameter is found to be C = 0.25 (compared with the actual C = 0.16). This configuration will provide a similar to 15% increase in the rate of mass-transfer and similar to 40% increase in the maximum capacity of the column.