Through the transformation of the mechanical structure of the three-screw pump and rational selection of flushing fluid, the use of mechanical seals has been improved, the problem of frequent leakage of mechanical seals has been solved, the cost of equipment maintenance and maintenance has been reduced, and the continuous and stable production of the device has been ensured.

Since the triple screw pump is at the bottom of the stripper, corrosion of pipes and equipment, as well as impurities and reconstituted polymers are deposited at the bottom of the tower. Residues entering the tri-screw pump contain large amounts of impurities and polymers, and due to insufficient flushing volume Therefore, these impurities and polymers are inevitably deposited in the sealed chamber, resulting in the gap between the moving ring and the moving ring seat and the shaft sleeve being blocked, resulting in the action of the moving ring in the axial direction is inflexible or even stuck, and the spring is jammed. Astringent, can not provide the original design 0.586MPa end face pressure, resulting in the sealing surface can not be well affixed, the liquid film balance is destroyed, then the seal will appear a slight leak, with the polymer and foreign particles into the friction face, seal The surface is gradually worn out, coupled with axial compensation of the moving ring, resulting in an increase in the amount of leakage of the seal, which ultimately leads to complete failure of the seal.

According to the cause of the failure of the seal, we have targeted the following aspects of technological transformation: According to the specific working conditions of the three-screw pump, we chose the Aizhi 318 type single-face mechanical seal (container type) The main features are as follows: Fine centering is achieved through an automatic locking ring. The adjustable gland can be used directly with common bolts. The cartridge structure is easy to install. The spring is located on the outside of the auxiliary seal and is completely separated from the medium, preventing the spring from sticking. The dynamic ring adopts a floating integral non-inlay. The static ring is a z-shape designed through computer analysis. The advantage is that the heat dissipation is good and the heat should not accumulate.