DIRECT MEASUREMENT OF LOW LEVEL CHLORINE IN CRUDE OIL

摘要

Relatively high levels of salt in crude oils can be a serious issue due its corrosive characteristics. Direct monitoring of salt in crude has an important economic aspect for the petroleum industry. The salt level in crude oil can be determined by measuring the chlorine content since salt contributes the majority of the chlorine content in the oil. A compact chlorine detection engine is developed using monochromatic wavelength-dispersive x-ray fluorescence analysis. A doubly-curved crystal (DCC) is coupled with a low-power x-ray tube to provide an intense monochromatic beam for sample excitation. A second DCC is designed to collect Cl Kα (2.6 keV) x-rays to a proportional counter. The number of Cl Kα x-rays photons detected is directly proportional to the Cl (Chlorine) concentration in oil. Due to the very narrow energy band width of the collection DCC, interference of other elements in the crude oil is eliminated. A bench-top Cl analyzer based on this engine was made and the detection capability was evaluated. A minimum detection limit of 0.16 ppm was obtained with 300s measurement time. Measurement results on crude oil samples will be presented. The measurement background and sensitivity of the analyzer will be also discussed.