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

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Title: A comprehensive investigation of refinery preheaters foulant samples originated by heavy crude oil fractions as heating fluids
Authors: Behranvand, E
Mozdianfard, MR
Diaz-Bejarano, E
Coletti, F
Orzlowski, P
Macchietto, S
Item Type: Journal Article
Abstract: 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 °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.
Issue Date: 30-Mar-2018
Date of Acceptance: 13-Mar-2018
URI: http://hdl.handle.net/10044/1/58570
DOI: https://dx.doi.org/10.1016/j.fuel.2018.03.077
ISSN: 0016-2361
Publisher: Elsevier
Start Page: 529
End Page: 536
Journal / Book Title: Fuel
Volume: 224
Copyright Statement: © 2018 The Authors. Published by Elsevier Ltd. Under a Creative Commons license (https://creativecommons.org/licenses/by-nc-nd/4.0/)
Sponsor/Funder: UNICAT Ltd
Funder's Grant Number: N/A
Keywords: 0904 Chemical Engineering
0913 Mechanical Engineering
0306 Physical Chemistry (Incl. Structural)
Publication Status: Published
Appears in Collections:Faculty of Engineering
Chemical Engineering

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