Fouling Phenomena in Phenolic Sour Water Stripping Units during Heavy Oil Upgrading Operations: A Spectroscopic Characterization Approach

Abstract:

In thermal heavy oil upgrading, phenolic sour water is mainly produced by delayed coking and hydrocracking units. This acidic stream is very corrosive and shows a marked tendency to form ammonium bisulfide precipitates during hydrogen sulfide and ammonia stripping operations. For this reason, it is very common to relate ammonium bisulfide with fouling problems in this kind of facilities. In this work we report a particular case of fouling where the building-up of an obstructing solid deposit has nothing to do with ammonium bisulfide precipitation, but with the formation of a black, solid-like, organic material. A spectroscopic approach based on FTIR, XRF, XRD, GC/MS, and Ion Chromatography techniques was used to characterize the solid deposit. Results revealed that this material comprised a mixture of organic and inorganic components. The inorganic portion (mainly metallic oxides) derived from corrosion reactions that took place inside the stripping tower; while the organic portion was highly soluble in toluene and chloroform, but insoluble in n-heptane. Even though this solubility behavior resembles the one showed by asphaltenes, spectroscopic results indicated that the organic portion was not asphaltenic in nature, but phenolic with a high polymerization degree. To the best of our knowledge, phenol polymerization has not been reported as a fouling promoter in sour water stripping units, so this might be the first documented case.

Año de publicación:

2015

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