Volume 5, Issue 5 (September 1977)
Evaluation of Filter/Separators and Centrifuges for Effects on Properties of Steam Turbine Lubricating Oils
A study was undertaken to determine the feasibility of using filter/separators in a bypass water-removal system for steam turbine lubricating oils. Twelve steam turbine oils were investigated in reduced-scale, 0.946 litre/min (0.25 gal/min), 500-h filter/separator experiments for effectiveness of water removal, effects of oil additives on performance of the filter/separator, and detrimental effects of filter/separators on oil properties. When effects on additives in the oil were indicated, restoration of the additives by adding up to 10% new oil was tried. Parallel investigations in a laboratory model continuous centrifuge were also conducted for comparison with the results obtained in the filter/separator investigations.
Satisfactory water removal effectiveness in filter/separators was demonstrated. Interactions of water-oil additives was encountered in varying degrees in eight of the twleve oils evaluated. Four of these oils were considered unsuitable for use unless reformulated. Since similar effects on oil additives may be encountered in either filter/separators or centrifuges, it is indicated that each oil should be evaluated for water-oil additive interactions to establish their suitability for use with water removal devices.