17-09-2012, 01:13 PM
SPREY DRYER
SPREY DRYER.ppt (Size: 5.74 MB / Downloads: 100)
INTRODUCTION TOSPREY DRYER
A spray dryer is a device used in spray drying. It takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporized. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximizing heat transfer and the rate of water vaporization. Droplet sizes can range from 20 to 180 μm depending on the nozzle. There are two main types of nozzles: high pressure single fluid nozzle (50 to 300 bars) and two-fluid nozzles: one fluid is the liquid to dry and the second is compressed gas (generally air at 1 to 7 bars).
Spray dryers can dry a product very quickly compared to other methods of drying. They also turn a solution, or slurry into a dried powder in a single step, which can be advantageous for profit maximization and process simplification.
INFORMATION OF MIXING VESSELS
To perform the CFD analysis of the posed physical problem, the mixing tank vessel containing four baffles is discretised withfinite volumes. In the interior four rotating impeller blades are connected to a shaft which runs vertically through the vessel(Fig. 1). Air is injected into the vessel through an inlet pipe located bellow the impeller blade at a speed of 5 m/s. The angularvelocity of the shaft is 3 m/s