METHOD OF VACUUM DRYING OF LIQUID VISCOUS MATERIALS Russian patent published in 1999 - IPC

FIELD: food-processing, pharmaceutical, medical and chemical industries; drying liquid viscous materials, mainly, colloidal and aqueous solutions. SUBSTANCE: material to be dried is placed on heated trays in vacuum chamber; drying process is conducted in three stages. At first stage, material is heated to temperature below boiling point of free moisture contained in material; at second stage, material is heated to boiling point and bound moisture is removed forming required structure of material and at third stage, pressure in chamber is reduced to lowest level and temperature of heating is raised to critical level specified for material being dried. It is good practice to abruptly relieve residual pressure in chamber at the second stage after bringing the material to boiling state. EFFECT: reduced drying time and consequently reduced expenses.