Mixing (process engineering)

Mixing is the inverse of separation and a basic operation in mechanical process engineering.

Mixer as a mechanical device or machine and the mixing processes thus generated we encounter in many areas: in the kitchen ( blender ), in the car ( carburetor ), with hand-washing ( mixing valve for hot and cold water), construction ( concrete mixers, " Blender " ), and in many industrial process steps.

Definition

In mixed technical procedures which are components of at least two separately present starting materials are repositioned by relative movement so that a new ordering scheme is created. The result is a mixture ( mixture ) and under certain conditions a new substance.

Criteria of a mixing process

Primary goal is to achieve a required homogeneity of the new material. The economical and procedural points of view, the mixing time and the time taken for the mixing process of energy is important.

For substances that do not spontaneously mix homogeneously, it is important that the mixer brings as much relative movement to be mixed Good. Ideally, this change intensity and direction of the force input constantly.

Calculation of mixing processes

A mathematical representation of a mixing process is not possible or only with great effort. It is therefore dependent on model experiments, are obtained in the dimensionless parameters that allow for scaling of the model.

The aim of the homogeneity of the new material is achieved when each sample reflects a composition corresponding to the population, so if a random sample reflects the ratio of the starting materials with a defined accuracy.

The method and device

Process engineering can be divided into mixer eg:

  • Compulsory mixer
  • Free-fall mixer
  • Stirrer
  • Kneader
  • Flow mixer
  • Mixing pumps

Other characteristics include:

  • Design: for example, twin-shaft batch mixers, drum mixers, pan mixers, ploughshare mixers
  • Mixing tools: for example, paddle mixers, ribbon blender
  • Mixed product: for example, feed mixer, ointment mixer

For mixing substances

  • Mixing a phase Solids with solids: dry mixtures (eg, cereals, feed, dry mortar )
  • Liquid with liquid: liquid mixing (eg, mixed drinks, lukewarm water)
  • Gas with gas: gas mixture (eg welding )
  • Solid with liquid: suspension, paste, moistening ( eg concrete, paint, cream)
  • Solid with gas: aerosol, dust, fluidization (eg, fluidized bed combustion )
  • Liquid with gas: atomization, atomization, ventilation (eg carburetor )
  • Chemical Reaction Engineering: catalyst with gas in liquid
  • Biological Reaction Engineering: microorganism with gas in liquid

Mixer designs for mixtures of solids and solid -liquid mixtures

  • According to which method: Batch mixers or batch mixers
  • Continuous mixers or continuous mixers
  • Critical ( Mischgutbeschleunigung > gravity acceleration; Froude number > 1.0 )
  • Subcritical ( Mischgutbeschleunigung < gravity acceleration; Froude number <1.0 )
  • Dynamic mixer ( energy input by the camera)
  • Static mixer ( energy input by the mix )
  • Horizontal mixer (horizontal mixing shaft or mixing shafts )
  • Vertical mixer (vertical mixing shaft or mixing shafts )
  • Shaft mixer
  • Double shaft mixer
  • Multi-shaft mixer
  • Drum mixer
  • Pan mixer or ring pan mixer
  • Tube mixer
  • Pan Mixer
  • Cone mixer
  • Vacuum mixer
  • Gas jet mixer

List of mixing equipment after use / industry use

  • Concrete
  • Slurry mixer
  • Laboratory mixer
  • Pharmaceutical mixer
  • Dry material mixer
  • Steam-water mixer
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