Abstract: A mixing device, especially for a fermenter, capable of dispersing gas in a broth therein, in which a number of propeller mixers are provided on a vertically extending shaft. The lower propeller mixer is a gas dispersing mixer having a hollow hub and open channels on the blades extending from this hub and tapering outwardly. At least one intermediate propeller mixer has some blades shorter than others and of reverse flow direction, some blades having baffle bars on trail edges thereof. The upper propeller mixer has the longer blades without channels and flow modifying elements.

Abstract: Complex mixing system with stages consisting of propeller mixers of high diameter ratio, where the blades are provided with flow modifying elements, whereby the energy proportions spent on dispersion of the amount of gas injected into the reactor, homogenization of the multi-phase mixtures, suspension of solid particles, etc. and the properties corresponding to the rheological properties of the gas-liquid mixtures and to the special requirements of the processes can be ensured even in extreme cases. Open channels (5) opposite to the direction of rotation are on the blades (4) of the dispersing stage (2a) of the propeller mixers (2) fixed to a common shaft, where the channels (5) are interconnected with gas inlet (7). The angle of incidence of a certain part of the blades (4) of mixing stages (2b, 2d) used for homogenization and suspension is of opposite direction and the length is shorter and/or the angle of incidence is smaller than those of the other blades.

Abstract: The apparatus has a column (1) of closed interior. Pipe (7b) leading into its upper part to admit liquid of higher density, and pipe (7a) leading into the lower part to admit liquid of lower density. Pipes (8, 10) emerge from the lower part to discharge liquid of higher density, and from its upper part to discharge liquid of lower density. Level control and propelling force adjusting mechanism (9) is connected with the pipe discharging liquid of higher density. Dispersing-mixing elements surrounding cells are beneath and above each other in the column (1). Pulsator (4) is connected with the lower part of column (1). The dispersing-mixing elements are formed by discs (5) having elastic tongues (13a) in the plane of discs capable for vibration and to move out of the disc's plane during vibration, and gap (14) runs along the periphery of the tongues (13a).