High pressure spray process
High pressure spray processes are used to produce powders in areas where conventional processes such as grinding, crystallization, sieving and drying are no longer sufficient. They are preferably used to generate small particles or particles with a high proportion of liquid. These substances are used in the chemical and pharmaceutical industry, the food industry and many other areas. The processes are under development and are therefore not yet widely used industrially.
Procedural principle
A solid is brought into solution under high pressure, possible temperature increase and mostly with a supercritical fluid . When relieved, for example through a nozzle , it crystallizes, dries or solidifies. The resulting particles differ considerably from the classically produced particles, especially in terms of morphology.
The solvents used include, above all, highly compressible, non-toxic and inexpensive gases that have good dissolving power under high pressure. CO 2 is often used .
The most popular micronization processes are listed below.
- RESS (Rapid Expansion of Supercritical Solution)
- CPF (Concentrated Powder Form)
- PGSS (Particles from Gas Saturated Solution)
- SAS (Supercritical Anti-Solvent)
- SEDS (Solution Enhanced Dispersion by Supercritical Gases)
The CPF process, however, is not a pure high pressure process, but a high pressure agglomeration process. The solution is applied to a carrier material with relaxation, creating a free-flowing powder.
literature
- Henning Gunnar Brandin: Production of powdery composites using high pressure spraying . Dissertation, Bochum 2005
- Andreas Kilzer: Production of fine powders from highly viscous polymer melts using high pressure spraying . Dissertation, Bochum 2003
- Peter Kappler: Particle formation and morphology in the high-pressure micronization of gas-containing solutions . Dissertation, Bochum 2002