Entrained flow - Flugstrom
In process engineering, entrained flow is a two-phase flow consisting of a gas and a solid (more rarely also a liquid), ie a flowing aerosol . The direct contact between the two substances is used in various technical processes in order to achieve a particularly intensive and rapid exchange of substances or heat .
- Entrained flow reactor , e.g. B. Entrained flow carburetor
- Entrained flow dryer , e.g. B. Spray drying
- Entrained flow firing , e.g. B. Dust firing
- Entrained flow heat exchanger , e.g. B. the countercurrent cyclone cascade in a cement plant
A disadvantage of such a method can be that the solid may have to be separated again from the gas carrier medium after the desired exchange has been completed, for which an additional unit, e.g. B. a cyclone separator (see picture) is required.
The fluidized bed represents a borderline case of the entrained flow . This is a two-phase flow in which the gas rises in a vertical direction, but the particles remain in suspension due to an equilibrium between lift and sink. In this way, particularly long residence times can be achieved.
Another special case is air conveyance as a type of pneumatic conveyance of bulk materials . Here the gas (usually air) only serves as a carrier for transport; there is no intentional heat or mass transfer.