The disc dryer, compared with other indirect drying equipment, has the advantages of large heat transfer area, good stirring effect, and better promotion of water evaporation and removal. It is a newly developed improved indirect heating dryer. The rotary dryer is mainly composed of a stator (shell), a rotor (rotary disc), and a driving device.
(1) Rotor
The central shaft of the rotor is the load-bearing component of the drying turntable, which is a hollow shaft on which all the turntables are welded. Each turntable is made up of two interlocking disks welded together. The inner cavity of the central axis is connected to all the inner cavities of the turntable. In order to improve the robustness of the turntable, there are many support rods distributed in the hollow turntable cavity, and the two ends of the support rods support the left and right disks. According to the different properties of the dried material, the turntable can be made of low-carbon steel, stainless steel, or special alloy steel. There is a pusher/agitator installed at the edge of the turntable, which has two functions: one is to push and transport materials, and the other is to stir and mix materials. The inclination angle of the thruster can be adjusted. The inner cavity of the turntable can be filled with medium and low pressure steam, heat transfer oil, or high-pressure hot water to transfer the heat required for drying the product.
(2) Stator
The stator is approximately a cylindrical shell, with the upper part raised to create space for accommodating sludge and waste steam, and equipped with a waste steam outlet. The stator end plate is installed with flanges for easy maintenance, and it is also used to fix the bearings of the rotor. For the convenience of maintenance, the exhaust steam dome outlet is also equipped with a maintenance cover plate.
(3) Drive motor
The entire driving device consists of an embedded gearbox, belt drive, coupler, and motor, which are used to drive the rotor to rotate slowly.
(4) Propulsion/Agitator
The function of the rotary dryer is to evenly and slowly transport the sludge through the entire dryer by the pushing/stirring action at the edge of the rotary disc, and dry it through thermal contact with the rotary disc. During the drying process, hot steam condenses on the inner wall of the turntable chamber, forming condensed water. The condensed water is introduced into the central pipe through a pipe and finally exported out of the dryer through an outlet groove. A scraper is installed between every two disks, and the scraper is fixed on the housing (stator). Scrapers can loosen the sludge between the discs, allowing waste steam to quickly leave the sludge. The heat transfer medium of the dryer is generally saturated steam with a pressure range of 0.2Mpa to 0.6Mpa.

Characteristics of rotary dryer:
(1) Contact drying (indirect drying, with no direct contact between thermal conductive medium and sludge)
(2) The degree of final sludge drying can be flexibly adjusted according to customer requirements, such as reducing the sludge moisture content from around 80% to 40%, 30%, 20%, 10%, and 5%.
(3) Applicable to all sludge disposal schemes (incineration, landfill, or use as fertilizer)
(4) The low oxygen content in the equipment system eliminates the possibility of dust explosion
(6) The sludge load inside the machine is large, and even if the feeding is uneven, it can ensure smooth operation
(7) Large load, easy to control
(8) Durable and sturdy construction
(9) The rotor speed is very low, 4-5 revolutions per minute, with minimal wear
(10) The design is very compact, but the heat transfer area is large, and the equipment occupies less space compared to other drying machines in terms of factory space
(11) Less maintenance, good continuous operation, can operate day and night, ensuring 7200 hours of operation per year
(12) Energy saving
(13) Power outage status can be activated urgently and run stably
(14) The drying equipment is completely sealed, with minimal odor generation and a good working environment
(15) High market share