Sprühgranulation

Sprühgranulation, or spray granulation, is a process used in food, chemical, and pharmaceutical manufacturing to convert fine powders into granules by spraying a liquid binding solution onto a powder bed while drying with heated air. The sprayed droplets bind particles as the solvent evaporates, forming granules with defined size, density, and porosity.

The process is typically carried out in a spray granulation reactor that combines a nozzle for atomizing the binding liquid with a drying chamber. A binder solution or suspension is atomized into the powder bed or a circulating powder stream; the hot air dries the droplets and promotes adhesion to create granules. Operations can be conducted in co-current or counter-current flow, and parameters such as temperature, feed rate, binder concentration, and atomization conditions determine the final particle size distribution and moisture content. Variants include single-fluid and two-fluid nozzles, and configurations that resemble spray drying with granulation.

Common binders include polyvinylpyrrolidone (PVP), hydroxypropyl cellulose, carboxymethylcellulose, and various polymers; solvents are often water or organic solvents, depending on the formulation. Substrates may be lactose, microcrystalline cellulose, or other pharmacopeial excipients, among others.

Applications are widespread in the pharmaceutical industry for producing granules suitable for tablet or capsule manufacture, as well as in the food, agrochemical, and specialty material sectors. Advantages include improved flowability, compressibility, and content uniformity; the method also allows rapid drying and scalable production. Limitations involve solvent handling, energy consumption, and potential thermal sensitivity of actives, which require process optimization and regulatory considerations.