Through the transformation of the mechanical seal structure of the three-screw pump and the rational use of flushing fluid, the service performance of the mechanical seal is improved, the problem of frequent leakage of the mechanical seal is solved, the cost of equipment maintenance and repair is reduced, and the continuous stable production of the device is ensured. As the three screw pump in the bottom of the stripping tower, pipelines and equipment corrosion and impurities and heavy polymer are deposited in the bottom of the tower, into the three screw pump body contains a lot of impurities in residual oil and polymer, at the same time due to insufficient flushing volume , So that these impurities and polymers are inevitably deposited in the sealed chamber, resulting in the moving ring and the ring seat, the gap between the sleeve is blocked, resulting in the ring moving in the axial direction is not flexible or even stuck, the spring is stuck Astringent, can not provide the original design pressure of 0.586MPa end face, resulting in the sealing surface can not be properly affixed and liquid film balance is destroyed, then there will be leakage seal leaks, as polymer and impurity particles into the friction end face, seal Face gradually wear, coupled with the axial compensation ring is not working, resulting in increased leakage seal, eventually leading to complete failure of the seal. Three screw pump mechanical seal According to the failure of the seal, we targeted from the following aspects of the technological transformation: According to the specific conditions of the three screw pump conditions, we chose Ai 318 type single-ended cartridge mechanical seal Cartridge) Its main features are as follows: Precise centering by automatic locking ring. Adjustable gland can be used directly with the commonly used bolts, container-mounted structure easy to install. Spring is located outside the auxiliary seal, completely separated from the media to avoid the jamming of the spring. Ring is used in the overall floating non-mosaic, static ring is a computer analysis, the design of the z-shaped, its advantages are good heat dissipation, heat should not accumulate.