A comprehensive investigation of refinery preheaters foulant samples originated by heavy crude oil fractions as heating fluids

FUEL

卷:224

Article

Behranvand, Elaheh¹  Mozdianfard, Mohammad Reza¹  Diaz-Bejarano, Emilio²  Coletti, Francesco^3,4  Orzlowski, Pawel²  Macchietto, Sandro^2,3 

[1] Univ Kashan, Engn Fac, Chem Engn Dept, Kashan, Iran

[2] Imperial Coll London, Dept Chem Engn, London SW7 2AZ, England

[3] Hexxcell Ltd, Innovat Hub, White City Campus,80 Wood Lane, London W12 0BZ, England

[4] Brunel Univ London, Coll Engn Design & Phys Sci, Uxbridge UB8 3PH, Middx, England

关键词: Refinery foulant characterization;    Fouling mechanism;    Corrosion;    Vacuum gas oil;    Vacuum bottom;    Iron oxide;   

DOI  :  10.1016/j.fuel.2018.03.077

来源: Elsevier

【 摘 要 】

A deep understanding of the mechanisms responsible for fouling from both crude oils and their fractions is paramount to ensure efficient energy recovery in heat exchangers of crude preheat trains. In this work, seven samples of fouling deposits, carefully collected from a number of refinery heat exchangers processing vacuum gas oil (VGO) and vacuum bottom (VB) streams in an atmospheric crude preheat train were investigated using a range of characterization techniques with the aim of identifying the underlying mechanisms that led to deposition. Characterization of the deposits included morphological and physical examination, fractionating solubility test, Scanning Electron Microscopy-Energy Dispersive X-ray, Combustion Analysis and X-ray Diffraction. In all samples examined, more than 75 wt% of the deposits were identified as inorganic, with about 50 wt% being FeS. At 270-300 degrees C, FeO(OH) was also identified to be deposited on the tube surfaces made in Cr steel alloy, where more fouling and less corrosion were evident compared to carbon steel (CS). These observations were found in agreement with recent laboratory studies aimed at identifying the role of temperature and tube material in petroleum corrosion. Furthermore, sulphur crystals were found in several VGO fouling samples. Based on the experimental results obtained, a mechanism was proposed to explain the corrosion fouling phenomenon, considered to be the underlying mechanism affecting the refinery. The mechanism involves naphthenic acid attack to the tubes' metal surface, decomposition of iron naphthenate, disproportion of iron oxide and sulphidation reactions. The results highlighted the importance of studying deposits formed under industrial conditions, timescales and variation of the deposition process, evidenced by the deposit characteristics, along extensive heat exchanger networks.

【 授权许可】

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