Vaccum dryer

Working of Vaccum dryer

1. Construction and Working of Vacuum Dryer

2. Vacuum Dryer Vacuum drying is the mass transfer operation in which the moisture present in a substance, usually a wet solid, is removed by means of creating a vacuum. Vacuum Drying is a process in which materials are dried under reduced pressure environment, which lowers the heat needed for rapid drying.

3. Vacuum drying is generally used for the drying of substances which are  hygroscopic  and heat sensitive, and is based on the principle of creating a vacuum to decrease the chamber pressure below the vapor pressure of the water, causing it to boil. Principle: Vacuum Dryer is basically works under reduced pressure by application of vacuum.

4. Construction and Working :

5. Vacuum Dryer consist of following parts: • Iron heavy jacketed vessel. • Hallow shelves. • Metal trays. • Oven to vacuum pump.

6. Vacuum dryers are sometimes made up of cast iron, but most now are made of stainless steel, so that they can bear the high vacuum pressure without any kind of deformation . The Vacuum dryers is divided into hollow trays which increases the surface area for  heat conduction  .The oven door is locked air tight and is connected to vacuum pump to reduce the pressure.

7. Advantages : • Easy operating • Easy for batch process of different compounds. • Various modes can be used for heating. Disadvantages: • Low heat transfer efficiency. • Limited capacity. • More expensive.

8. Application: • Drying of heat sensitive material, dusty hygroscopic material. • Drugs containing toxic solvents.