Vacuum application
When a vacuum is applied, a process space is evacuated. The pressure is lowered below atmospheric pressure. The aim is to lower the boiling point of liquids, remove oxygen, or influence reactions. In a moist system with a large specific surface area (moist powders), generating a vacuum means a very efficient temperature reduction of the moist powders.
A vacuum can be generated with vacuum pumps, ejectors, or vacuum systems. The pressure is measured and controlled via sensors. However, leaks and outgassing can significantly affect the attainable ultimate vacuum. In process engineering, the vacuum system is used for vacuum mixer-drying, distilling, reacting, degassing, and filtering. It enables gentle processes at low temperatures and under an inert atmosphere.
In doing so, it influences heat and mass transfer, the drying rate, and product quality. A fast and stable vacuum system reduces process times and energy demand.
dp/dt = - S/V · p
- P is the pressure in the apparatus volume
- S is the pumping speed of the vacuum pump
- V is the volume of the apparatus
- dp/dt is the rate of pressure reduction