Vacuum harrow dryer is mainly composed of shell, rotating shaft and harrow teeth. Different from the slurry leaf dryer, the rotating shaft and rake teeth of vacuum rake dryer are not used as the heating surface, it only serves as the role of stirring the material and updating the surface. The rake dryer is operated in vacuum, firstly, the wet material is added into the dryer, the heating medium (generally water vapor or hot water can also be used for heat conduction oil) is passed into the jacket, and then the vacuum pump is started, and after reaching the stipulated vacuum, the stirring device is started to make use of the positive and negative rotation of the rake teeth, so that the material can be pushed to the middle and the two ends continuously during the drying process, and meanwhile, four stainless steel rods (seamless steel pipes) can be placed between the rake teeth according to the requirements of the users. At the same time, between the rake teeth can also be placed according to user requirements 4 stainless steel rods (seamless steel pipe), which in the rotation of the shaft in the process of continuous up and down movement, vibration of the material bonded to the wall of the device and the material will be crushed lumps of material. Through these measures, the timely renewal of the heat transfer surface can be ensured, thus accelerating the rate of heat and mass transfer. Material drying to the specified moisture, stop heating, close the vacuum system, remove the dried material, complete a cycle of operation. This dryer is suitable for slurry, paste, granular and fibrous material drying, especially for heat-sensitive materials and requirements for the recovery of organic vapors drying operation, vacuum rake dryer has many advantages. Vacuum rake dryer rake teeth have left and right to the two basic forms, whether left or right are shaped and pulp leaf type two kinds of installation, the neighboring rake teeth between the difference of 90 degrees orientation, the two ends of the shaft to install shaped rake teeth, the rest of the installation of the pulp leaf type rake teeth. When the shaft rotates, the material moves to the two sides first and then to the center under the action of the stirring shaft, so as to ensure that the material is always in a uniform stirring state during the whole drying process.