PEFTEC 2019 - Abstract

Abstract Title: Standard Free XRF Screening of Fouling Samples from Steam Crackers
Abstract Type: Oral
Session Choice: Analytical Techniques: Elemental Analysis and Speciation
Presenter Name: Dr Christian Wold
Co-authors:Mr Barry van Hooff
Dr Fabrice Cuoq
Company/Organisation: SABIC
Country: Netherlands

Abstract Information :

Fouling may be defined as deposits of erroneous material that build up during production and is a common problem in processes. Particularly for steam cracker operation, fouling is a great concern at industrial scale and may be encountered in many forms and various sections of the plant. Of course fouling may be related to an economic negative effect due to, for example, decreased efficiencies due both to interruptions, maintenance and increased fuel and hence energy uses. This in turn relates to the environmental footprint of a petrochemical cracking plant.

Despite the screening of feeds by a variety of techniques including for example CCR, Elemental analysis and Comprehensive Two Dimensional Gas chromatography some fouling through either deposition of inorganic species, formation of polymeric species, or through coke formation is inevitable. For continuous improvement of operations, it is important to be able to assign fouling issues to their root cause that can be broadly defined as either inorganic or organic.

For inorganic fouling the concentrations of most important elements are at a high part per million or low percentage level having been concentrated in the process over time and very suitable for the XRF technique. The main challenge for providing good data is dealing with the inherent sample inhomogeneity and the lack of any matrix matched calibration standards. In recent years, the accuracy and precision of standard-less analysis software packages used in XRF have been improved. Such approaches rely on estimation of the matrix effect on the measurement signal and take into account instrument parameters in order to estimate the amount of elements in a given sample and provide excellent characterization and analysis results of unknown samples especially where no certified reference standards are available.

In this work, we investigate the applicability of the standard-less XRF method for the analysis of inorganic fouling samples from a steam cracking process. We present a method for reducing the sample inhomogeneity and the subsequent sample preparation and measurement that is validated against ICP-MS data. The resulting method is fast, robust and perfectly suited for fast analysis of samples for urgent intervention and able to handle large amounts of samples encountered for example during plant shut down and maintenance activities.