Shaft seal device

Abstract

A shaft seal device including a casing having a hollow portion, a rotable shaft extending inside the casing from a sealed fluid region to an outer region, a non-contact type first mechanical seal arranged between the casing and the shaft so as to divide the hollow portion into the sealed fluid region and a purge region located between the sealed fluid region and the outer region, and a second mechanical seal arranged between the casing and the shaft so as to divide the hollow portion into the purge region and the outer region. The first mechanical seal includes a first rotating seal ring having a first rotating seal surface rotating along with the shaft and a first non-rotating seal ring held by the casing and having a first non-rotating seal surface able to abut axially and slidable against the first rotating seal surface, a plurality of first hydrodynamic grooves communicating with the purge region formed at the first rotating seal surface or the first non-rotating seal surface so as to extend from an inner circumferential edge thereof to an outer circumferential edge direction, and a purge fluid higher in pressure than the pressure of the sealed fluid fed into the purge region.