Gas compressor having a dry gas seal on an overhung impeller shaft.

摘要

A gas compressor, particularly of the kind for boosting pressure in gas transmission and petro chemical process, has an impeller (30a) mounted on an impeller shaft (22) of the overhung type mounted on front and rear bearings (24,25) and having at least one impeller mounted between the front bearing and a front end of the shaft. Annular seals are provided coaxial with the shaft which separate an inner space communicating with the shaft front end from the suction end gas space which lies outside the seals. The seals include an outer seal (74) and an inner dry gas seal (76). Pressurised process gas is supplied between these seals at a pressure higher than suction pressure and is vented from the inner gas space at a pressure well below suction pressure to limit gas pressure forces on the front end of the shaft.