Homogenisation is a very important process in, for example, the pharmaceutical industry, as it ensures that the same proportion of a substance, in particular the active substances, is contained in any quantity of a medication.
One of the best known applications is the homogenisation of milk. The fat globules present in the milk are atomised to a uniform size in the homogeniser, so that they are distributed evenly in the milk. This process prevents the “creaming” of the milk. This process is also used in the cosmetic and chemical industries, for example in the production of
The particular challenge with homogenisation is to mix non-miscible liquids with solids, if necessary, without the formation of lumps. The homogeniser is to be selected depending on the raw materials to be processed and the process. High shear rates/shear energies are particularly useful in the upper performance spectrum, when the finest emulsion droplets have to be guaranteed.
Depending on requirements, special homogeniser facilities are useful, such as:
- Sucking of different phases directly in the toothing area
- The dilution of ether sulphate in the continuous process method,
- The incorporation of powder substances
- The simultaneous dosed feeding of several liquid phases
The aim of dispersion/homogenisation
- To achieve the break-up of a droplet, the stresses applied to the droplet must exceed a critical level.
- The deformation time should be sufficiently long, in order to allow the droplet to break up and the resulting droplet surfaces to be coated with emulsifiers to prevent subsequent coalescence.
- The type of energy input in the dispersing zone determines which forces act on the droplet and reduce its size.
- The newly formed droplets are stabilised by the absorption of emulsifier molecules on the newly formed phase boundary and by hydro-dynamic effects.
- Droplets that are insufficiently stabilised tend to coalesce in a collision (e.g. lack of emulsifiers).
Influences on the droplet size
- The shear energy (shear-rate dv/ds)
- The appropriate emulsifier
- Dwell time of the droplets in the toothing area
- Suitable stabilisers (thickener, gelling agent)
Negative influences on uniform droplet forming
- Cavitation in the shear area (no defined conditions in the shear area of the rotor/stator toothing.
- Too short dwell time within the toothing.
The required process and the desired level of automation determine the choice and design of the homogenising system. We will be glad to set out the optimal design variant for you and are, of course, also the perfect contact persons for the technical design of solutions which do not meet the standard.