Analytical Instrumentation

  • Analysis of Sulfur and Metals in Crude by EDXRF
    Rigaku NEX DE Energy Dispersive X-ray Fluorescence Spectrometer
  • Calibration and Detection Limits
  • Sample Standards

Analysis of Sulfur and Metals in Crude by EDXRF

Oct 15 2019 Read 320 Times

Scope

The analysis of sulfur, calcium, vanadium, iron and nickel in crude is demonstrated. The measurement is also applicable to residual oil, bunker fuels and other heavy hydrocarbon oils.

The Rigaku NEX DE Energy Dispersive X-ray Fluorescence (EDXRF) elemental analyser complies with ASTM D8252-19, Standard Test Method Vanadium and Nickel in Crude and Residual Oil by X-ray Spectrometry.

NYMEX/CME specifications allow for maximum levels of 8 mg/kg Ni and 15 mg/kg V for light sweet crude oils futures contracts. NEX DE is used as a simpler, faster alternative to ICP to meet the NYMEX/CME requirements.

Background

Sulfur, vanadium and nickel occur naturally in crude oil, and their concentrations vary depending on the geographical region of the oil deposits. Depending on the region some crude may also contain measurable levels of calcium and iron. High metal content can foul the refining process during cracking, and so low metal crude is desirable. At the refinery as well as midstream at pipelines, transportation, gathering points and during blending a quick and easy means of screening and monitoring the metal content is a valuable tool in characterising the quality of the crude before refining. Rigaku NEX DE EDXRF analyser is an ideal multi-element tool for monitoring the concentrations of not only sulfur and metals in crude, resid and other heavy hydrocarbons.

Instrumentation

Model: Rigaku NEX DE 
X-ray tube: 12W 60kV Ag-anode 
Detector: High Throughput SDD 
500,000+ cps 
Sample Type: Crude 
Film: 4um Polypropylene 
Analysis Time: 700 sec 
Optional: Single Position or Autosampler 
Environment: Air

Sample Preparation

Ensure each oil sample is homogeneous and stable. Simply fill an XRF sample cup 3/4 full (4g) and measure directly.

Calibration

Empirical calibrations were built using a suite of 10 commercially available mineral oil calibration standards that represent crude, resid and other heavy hydrocarbon oils.

Repeatability

To demonstrate repeatability (precision), three calibration standards were measured in 10 repeat analyses using an analysis time of 700 sec per sample without moving the sample between measurements. Shorter measurement times can be used if such excellent precision is not required.

Detection Limits (LLD – Lower Limit of Detection)

In the empirical method, ten repeat analyses of a blank mineral oil sample are taken with the sample in static position, and the standard deviation (σ) is determined. The LLD is then defined as 3σ. Shorter measurement times can be used if such low detection limits are not required.

Conclusion

The Rigaku NEX DE spectrometer gives technical and non-technical operators alike a simple yet powerful and versatile system for quantifying multi-elemental composition using the empirical approach. The results indicate that given stable samples, proper sample handling and calibration technique, the NEX DE achieves excellent performance for monitoring sulfur and metals in crude and other heavy hydrocarbon oils.

Reader comments

Do you like or dislike what you have read? Why not post a comment to tell others / the manufacturer and our Editor what you think. To leave comments please complete the form below. Providing the content is approved, your comment will be on screen in less than 24 hours. Leaving comments on product information and articles can assist with future editorial and article content. Post questions, thoughts or simply whether you like the content.

Post a Comment




Digital Edition

Petro Industry News November 2019

November 2019

In This Edition Fuel for Thought - Leading European sensor trade event taking place in 2020 already selling out fast - Endress+Hauser and Vector CAG secure contract at large Texas refinery...

View all digital editions

Events

Oil. Gas. Chemistry

Nov 20 2019 Krasnoyarsk, Russia

INCHEM TOKYO 2019

Nov 20 2019 Tokyo, Japan

Mozambique Gas Summit

Nov 20 2019 Maputo, Mozambique

Miconex

Nov 25 2019 Beijing, China

East Africa Oil & Gas Summit & Exhibition

Nov 26 2019 Nairobi, Kenya

View all events