Spherical digester is mainly composed of spherical shell, shaft head, bearing, transmission device and connecting pipe. Digester shell a spherical thin-walled pressure vessel with boiler steel plates welded. High welding structure strength reduces the total weight of the equipment, compared with riveting structure can reduce around 20% steel plates, currently all spherical digester adopts wielding structure. Max designed working pressure for spherical digester is 7.85×105Pa, in sulfur cooking process, spherical digester corrosion allowance can be at 5~7mm. A 600 x 900mm size oval hole is opened at the vertical center line of spherical shell for material loading, liquid delivery and maintenance. In order to ensure the safety of spherical digester, a circle of reinforced steel plates are wielded around the oval opening. Loading hold is equipped with ball cover, after loading material it will be fastened with a bolt from inside. For long-fiber raw materials, the loading opening is also the discharge opening. Inside spherical shell equipped with multi-porous tube to increase steam distribution area, which ensures the even cooking of raw material. To reduce the friction between the slurry and the inner wall, the sphere is connected with two cast steel hollow shaft heads through the flange and is supported on the semi-open oil ring bearing, which is fixed on the concrete stand. One end of the shaft head is connected with steam inlet pipe and the other end of the shaft head is connected with the discharge pipe, the pipe is equipped with shut-off valve, pressure gauge, safety valve and stop valve. In order to prevent heat loss during cooking process, the outer wall of the spherical digester is usually covered with a 50-60mm thick insulation layer.
The advantages of spherical digester: raw material and cooking agent can be fully mixed, the concentration and temperature of the liquid agent are more uniform, the liquid ratio is low, the concentration of the liquid agent is relatively high, the cooking time is short and the surface area is smaller than vertical cooking pot with the same capacity, saving steel, small volume, simple structure, easy operation, low installation and maintenance costs etc.
Post time: Jun-14-2022