A Practical Trace Element Monitoring System for Intermediate Gas Turbine Fuels

Intermediate fuels (GT-3) are less expensive than distillates and do not cause difficulties in a gas turbine provided the contaminant level of the GT-3 oil is consistently kept below accurately set limits. The key to trouble-free operation is a reliable, relatively inexpensive and fairly fast on-site monitoring system. Experience with such a system was previously reported. The present paper discusses the on-site monitoring systems in some detail. The method provides results for metallic trace element analyses in the order of 10 ppm, within ±0.2 ppm, using the oil ash as the subject of investigation with a flame emission spectrophotometer, a colorimeter and an atomic absorption spectrophotometer. Elimination of interference effects is described and procedures for the appropriate solutions are shown. Investment costs and man-hour requirements are described.