When the vacuum drying machine is operated, the agitator is started, the dry material is added, and the feeding port is closed. At the same time, steam heating, heating steam pressure is generally 0.2~0.4Mpa (gauge). Vacuum pump to extract water vapor and non condensable gas, general material drying, vacuum degree is about 700mmHg. The water evaporation intensity of the dryer varies with the nature of the material, humidity, heating steam pressure and vacuum degree. For example, the vacuum degree is 700mmHg, heating steam pressure of 0.2Mpa (g), the potato starch from the initial moisture content of 40% dry to 20%, water evaporation intensity is 5~7 kg/m2 h dryer.
The operation of the vacuum dryer is lower than that of the box type dryer. The utility model can recover the useful moisture in the material, and has good operating conditions and convenient management. Its disadvantage is the low production capacity, equipment structure is more complex, easy to damage the agitator blade. The dryer is used more widely in the dye and pharmaceutical industries. For example, drying and reducing dye intermediates, anthraquinone sulfonic acid, salicylic acid, VAT olive green R intermediates, Kapulong polymer, two Aminoanthraquinones drying etc.. Vacuum rake dryer equipment structure.