2014 - MRO Dry Gas Seal Reliability Improvement WELCOME TO 2014 - MRO Dry Gas Seal Reliability Improvement

Presenter Presenter: Ali Shallwani Career Summary: Rotating Equipment Specialist at Nova Chemicals (2014-onwards) Rotating Equipment Engineer at Saudi based petrochemical company (2011-2014) Machinery Engineer at Pakistan based fertilizer plant (2007-2001) Career Highlights: Vibration Diagnostics, Initiatives related equipment design and performance improvement, RCFAs, FMEAs, PHAs

Problem Statement Low buffer flow for dry gas seal Primary Seal /Buffer Gas Supply Primary Seal Gas + Separation Seal Leakage Separation Seal Supply

Application Service: CO Machine: 7 Stages Integrally Geared Compressor (Steam Turbine Driven) Specific Stage: 7th Stage Operating Profile: 65barg Discharge Pressure

Internals Rotating face with spiral profile (uni-direction seal – specific case) Stationary face (spring supported) Espey rings or barrier seal Sleeve

Significance In case of low buffer flow – there is potential of oil ingress into the seal housing. Potential failure of seal assembly Equipment shutdown

Description Description Seal Type 2.937” Single Speed 27426 rpm Design Temperature -20C / 150C Static Design Pressure 75 bara Dynamic Design Pressure

Description N2 is used as buffer gas – which then escapes through the primary vent (to the flare). N2 pressure should be essentially maintained at recommended value to achieve this desired flow rate. As standard design, there is no trip security associated with buffer flow.

Troubleshooting The seal gas system for this specific set-up was checked. The important fittings and installations on the system includes transmitters, control valves and orifices. The low buffer flow was observed on 7th stage of the equipment – the remaining 6 stages were healthy. Potential leakage within the system was checked. Restriction within the system was to be checked.

Inspection The seal was disassembled for inspection. All internals were found in stable condition. The espey rings through which the buffer gas flows were found slightly rubbed against sleeve surface.

Modification The type of espey ring was modified such that grooves were introduced to ensure continuous supply for N2 in case of tight clearance / contact.

Outcome The desired flow rate through espey ring was achieved – and reliability of the overall system was ensured.