Rotary vacuum paddle dryer is a jacketed cylindrical vessel with a large diameter hollow shaft. Attached to the shaft are hollow paddles provided with specially designed scraper the entire internal surface of the dryer and continuously move and rotate the material thereby precluding the possibility of material remaining in contact with hot surfaces for protracted periods of time. The jacket and hollow shaft with paddles can be heated with hot water, steam or any other thermal fluid capable of providing a large indirect heat transfer area. Cooling can be also be done by cold water, brine or any other refrigerant through the jacket and hollow shaft. Limpet coil can be provided in lieu of jacket. if liquid heating medium is used. Hard facing of shaft provided in way of gland pack ing areas of trunions. Arrangements for nitrogen purging provided. Bag cleaning arrangements with pulsation by nitrogen jet injector provided. Heavy duty trunions and bearings support the hollow shaft (agitator) and the drive is provided by means of a motor through reduction gears chain and sprocket Provision has also been made to insert four breaker bars inside the dryer shell for particle size reduction. In special cases, stationary scraper blade can be provided to scrape the rotating agitator, for highly sticky materials.