We are facing problem of repeated Dry Gas Seal failure on an Integrally Geared Centrifugal Compressor. The Compressor consists of Bull Gear Driving 03 Pinions with each Pinion carrying 02 Impellers i.e. 01 Impeller at each end.
Each Pinion is axially located by 02 Thrust Collars that are running against Bull Gear Face. Bull Gear is Axially located by Thrust Bearing. Axial Probes are installed only on Bull Gear Shaft.
The Dry Gas Seal manufacturer has attributed the failure to Axial Vibrations. I am trying to understand the source of Axial Vibrations.
Is it possible that Axial Runout on Pinion Thrust Collar Face is causing To & For Axial Motion of Pinion in each revolution e.g. if Axial Runout on Pinion Thrust Collar Face is 0.012 mm TIR (API limit) and Pinion RPM are 21945, resulting axial movement will be 0.012 mm/revolution which implies Axial Vibration at rate of 4.389 mm/sec
Is it possible similar effect will be created by Face Runout of Bull Gear resulting either from machining tolerance or Bull Gear Shaft position within its Bearings (Say extreme right on Non Drive End Bearing and extreme left in Drive End Bearing) e.g. for 0.25 mm Bearing Clearance, Gear Dia to Bearing Span ratio of 1.5 and Gear RPM 1490 resulting movement will be 9.3 mm/sec
Please refer to the attached pdf for schematic of what I am thinking of