DE3622723C2 - - Google Patents

Description

The invention relates to a method for mixing substances, in which a stirrer with rotatably mounted and in their Anstell angle adjustable wings is used.

A propeller stirrer is known which is rotatably mounted and has adjustable wings in their angle of attack. Indeed the blades do not become there while the stirrer is rotating adjusted. This stirrer is obviously meant to be used before the actual mixing process a certain, to the mix adjust the adjusted angle of attack firmly and this during to keep the mixing process constant.

With the stirrer according to DE-AS 14 57 300 the angle of attack of the wing also adjusted. However, here is the stirrer stopped and when restarting in the opposite direction The wing therefore folds into the new position.

The wing is known from another branch of industry to change their angle of attack while turning. It han is the ship's propeller with adjustable blades, which is mainly used to drive ferries and fishing trawlers becomes. The wings of the propeller are pivoted and the angle of attack of these wings can be turned so far that the ship reverses with the screw turning in the same direction. When stirring, such a propeller is used while rotating is adjusted, not used.

All mixing tools produce irregular mixed streams mations also superimposed constant flows that lead to the mixing effect contribute little. These currents can be represented by vectors, whose direction and length are constant over time will.

However, it is much cheaper to create a flow pattern in where all flow vectors are constantly changing direction and length. Especially for the mixture of highly viscous liquids laminar flow and for the mixture of low-viscosity Liquids cause a permanent change in the flow pattern  to improve the mixing efficiency. At a Batch operation shortens the mixing time and in continuous operation with the same mixing effect the drive power can be reduced. This can be done by Reduction of mixer diameter or speed happen. When stirring solid suspensions "Dead corners" in which the solid settles, ver be avoided.

The formation of a trombone shows a constant flow by the centrifugal force of the mixing tool is fathered. The liquid or suspension is at the Mixing container wall upwards and from there into the drum funnel promoted. If this constant flow through a Counterflow disrupted, for example by a mixing tool, depending on the time a flow component up and generated downwards, so there can be an improvement in mixing achieve operation.

The object of the method according to the application is to prevent a constant flow in the mix.

To the solution this task provides that the adjustment of the employment angle of at least one wing while rotating the Stirrer is done while maintaining its sense of rotation.

This makes it possible to create a flow pattern in which the flow vectors constantly change their direction and length.

A particularly favorable procedure arises if the size of the angle of attack a stochastic process, so random control.

When creating the control program, one is possible great irregularity. You could, for example use the random program of a computer and everyone Assign a random angle to a random number. Or you use one fixed program, e.g. B. created by shuffling cards is, with each card be a certain angle of attack points.

With low-viscosity mix and with constant direction of rotation of the Stirrer there is a risk that the entire mix the Be orbital axis encircled. To prevent this and this con Interfering with constant motion is another convenient method as intended to reverse the direction of rotation of the stirrer.  

This eliminates baffles.

The procedure according to the application is not only limited to the Ver limited use of propeller stirrers, but can be with all stirrers that have swiveling blades.

Claims (3)

1. A method of mixing substances, in which a stirrer with rotatably mounted and adjustable in their blades is used, characterized in that the adjustment of the angle of attack of at least one blade is carried out while rotating the stirrer while maintaining its sense of rotation. 2. The method according to claim 1, characterized, that the size of the angle of attack of a random control is subjected. 3. The method according to claim 1 and 2, characterized, that the direction of rotation of the stirrer during the mixing process will be changed.