Arrangement for injecting additives into turbulent flow in passage

摘要

In an injection point for the introduction of additives into turbulent flowing fluids (or suspensions, or streams of fluidised solid materials), the cross-section through which the main stream flows is progressively narrowed by deliberate deformation of the wall enclosing the stream (e.g. a pipe or channel) and is expanded again to its full area at a pinch point (11, 12) designed to act as a vortex-shedding edge in order to achieve mixing of the additive with the main stream. The pinch point can lie in a plane which is at an angle of 90 degrees or less to the axis of the direction of flow of the main stream. The pinch point is produced by plastic deformation of the wall of the main passage by the application of an external force, and any resultant weakening is compensated by the use of external reinforcement so that the smoothness of the inner surface of the passage is retained. The additive is injected through one or more holes in the wall enclosing the main stream in the region of the pinch point, and a number of pinch points may be arranged side by side or in series for more intensive mixing. The wall of the main passage may be provided with pressure relief holes, and be embedded in an additional, pressure-containing sleeve.