Disclosed is a reactor or sparging vessel suitable for use for reaction mixtures containing vapor and/or gas bubbles. It comprises a mechanical agitation means suitable to redistribute flow radially and at least one perforated plate suitable to provide resistance to axial flow. In desirable embodiments it may include at least one electrically or hydraulically-stimulated rotatable shaft upon which at least one blade impeller is mounted, and at least one perforated plate oriented such that it provides resistance to axial flow. The perforated plate may have channels therethrough whose cross-sectional dimension is smaller than the projected average diameter of the vapor and/or gas bubbles. The reactor or sparging vessel offers improved flow dynamics, including reduced back mixing and narrowed residence time distribution. A method of employing the reactor for a reaction mixture containing vapor and/or gas bubbles is also disclosed. An impeller blade having two curvatures is also disclosed.