Sulfur and Chlorine in Crude

    Application Note EDXRF1331

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    Scope

    The analysis of sulfur and chlorine in crude oil is demonstrated.

    Background

    Monitoring the sulfur and chlorine content is important in various oils and oil products. In crude oil, chlorine may be present through natural processes or possible adulteration. If unmeasured or not corrected for, chlorine may bias the sulfur measurement or potentially cause damage in the refining process. The industry requires a fast, simple means of screening and monitoring the chlorine content of crude at the well site, along pipelines, during blending and other pre-refining checks. In these cases and others, Applied Rigaku Technologies meets the challenge of monitoring and measuring the sulfur and chlorine content of oils with the use of compact benchtop instrumentation that use semiconductor detectors. These systems can easily resolve and measure the sulfur and chlorine, as well as vanadium and nickel present in the oil. See also App Note #1323.

    NEX QC+ high-resolution EDXRF analyzerModel: NEX QC+

    Calibration

    Eight commercially available certified crude oil standards were used to develop empirical calibrations for S and Cl. The results shown here demonstrate measuring crude oil containing sulfur levels between 1 – 4% and chlorine between 25 – 1000 ppm.

    Element: S
    Units: %
    Sample I.D. Standard value Calculated value
    STD 3 1.152 1.147
    STD 4 1.554 1.553
    STD 5 1.952 1.961
    STD 6 2.501 2.504
    STD 7 2.701 2.702
    STD 8 3.202 3.192
    STD 9 3.607 3.607
    STD 10 4.003 4.007

    EDXRF1331 Correlation plot SCorrelation plot S


    Element: Cl
    Units: ppm
    Sample I.D. Standard value Calculated value
    STD 3 901 905
    STD 4 25 17
    STD 5 750 741
    STD 6 100 109
    STD 7 600 599
    STD 8 1001 1002
    STD 9 350 354
    STD 10 500 501

    EDXRF1331 Correlation plot ClCorrelation plot Cl

    Repeatability

    To demonstrate repeatability (precision), two typical calibration standards were selected. Each was measured in 10 repeat analyses without moving the sample between measurements.

    Sample: Std 4
    Element Standard value Average value Std. dev % Relative dev
    S (%) 1.554 1.572 0.006 0.4
    Cl (ppm) 25 21 2 8

    Sample: Std 8
    Element Standard value Average value Std. dev % Relative dev
    S (%) 3.202 3.187 0.014 0.4
    Cl (ppm) 1001 995 3 0.3

    Conclusion

    The NEX QC+ offers analysts and technicians a simple yet powerful and versatile system for quantifying elemental composition using the empirical approach. The results of this study indicate that given stable samples, proper sample handling and proper calibration technique, the Rigaku NEX QC+ EDXRF can achieve excellent results in screening and monitoring the concentration of sulfur, chlorine and other elements in crude oil and other similar oils.

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