Fluid hydrodynamic mechanical seal

The utility model relates to a fluid hydrodynamic mechanical seal used for a high temperature and pressure chemical centrifugal pump in the coal chemical industry of coal liquefaction, coal replacing oil, oil making from coal, etc. The fluid hydrodynamic mechanical seal comprises a moving ring seat, a moving ring, a spring, a shaft sleeve and a stationary ring, wherein the spring is arranged between the moving ring and the moving ring seat. The fluid hydrodynamic mechanical seal is characterized in that a plurality of fluid hydrodynamic slots are uniformly distributed on the end surface of the moving ring or the stationary ring, and the slot can make liquid to cool a farther sealing end surface strongly when a sealing ring rotates; when the cooling is carried out, comet-shaped lubricating wedges of which the number is equal to the number of the slots are formed on the initial surface of the sealing ring. The utility model can satisfy the maintenance of no leakage for conveying high temperature and pressure media for a long time and can also satisfy the high reliability, high stability and flexible tracing ability in high pressure of the mechanical seal. Thereby, the service life of a pump can be raised.