Spray drying is the classic thermal method for continuously drying liquids gently even in large quantities. Watery solutions, suspensions or emulsions are transformed into solid powders in one process step with the aid of the spray drying technology. Spray drying is a very gentle drying method, especially for sensitive substances such as hormones, proteins or vitamins.
In our spray drying plants at our Genthin site, we, as a contract dryer, can prepare or condition the starting materials in various process steps immediately before spraying. These include, among others, mixing, dispersion, emulgation, heating, cooling and neutralisation and conducting of chemical transformation reactions if necessary.
Process
In the spray drying, all starting materials are sprayed for drying. For liquids this is no problem, all other materials – such as waxes or meltable raw materials – are transformed into an atomizable state by suitable methods before beginning with the spray drying.
The starting materials are finely atomized in the top part of the spray tower during the spray drying process and brought into contact with a hot air stream. In free fall through the hot air, they dry in a split second (convection) into a fine powder. Depending on the result to be achieved by the spray dryer, the hot air can flow against or with the spray jet. The dry particles are separated from the air stream by a cyclone separator and can be removed without any problems.
The temperature in the spray drying technology is defined exactly, the heat exchange between the liquid droplets and the air is short but intensive. In this way, we create powdered particles with particles sizes between 20 and 200 µm in the spray dryer. The resulting form of the particle surface – often hollow spheres – guarantees the desired good solubility for many products.
Advantages
- Fast and controlled drying within seconds
- Brief thermal loading of the droplets or created particles
- Defined distribution of the particle sizes
- Creation of hollow spheres with good dissolution characteristics
- Improved dissolution behaviour and redispersibility in water
