Deposition of asphaltene from destabilized dispersions in heptane-toluene

Title: Deposition of asphaltene from destabilized dispersions in heptane-toluene
Authors: Campen, S
Smith, B
Wong, J
Item Type: Journal Article
Abstract: Deposition of carbonaceous materials, such as asphaltene, is a major problem in petroleum production. During production, changing environmental conditions destabilize asphaltene, resulting in dispersions that are out of equilibrium, where asphaltene is aggregating or flocculating. Key to developing the most effective strategies for tackling this problem is a fundamental understanding of asphaltene deposition behavior. A quartz crystal microbalance with dissipation monitoring (QCM-D) is used to study asphaltene deposition from destabilized dispersions generated by in-line mixing of asphaltene in toluene (a solvent) with n-heptane (a precipitant). The effects of heptane:toluene ratio and destabilization time are investigated. At high heptane:toluene ratio, the rate of asphaltene aggregation is faster, and large flocs form by the time the flowing liquid reaches the QCM cell. In this case, the rate of deposition decreases with deposition time. At low heptane:toluene ratio, the rate of asphaltene aggregation is slower; hence large flocs do not form before the flowing liquid reaches the QCM cell, and deposition of smaller aggregates occurs. Here, the deposition rate is constant with time. The deposited mass is greatest before the formation of large flocs and at short destabilization times, where the particle distribution is furthest from equilibrium. Destabilized small particles existing immediately after a destabilization event pose a greater deposition problem than the flocs that subsequently form. This may be a contributing factor in the existence of deposition “hotspots” at certain locations in the production pipeline. Pushing destabilized dispersions to their new equilibrium distributions as quickly as possible may be a preventative strategy to combat deposition. The dissipation–frequency relationship monitored by QCM-D is sensitive to the nature of deposited asphaltene films and may be used as a diagnostic tool.
Issue Date: 20-Aug-2018
Date of Acceptance: 20-Aug-2018
URI: http://hdl.handle.net/10044/1/63612
DOI: https://dx.doi.org/10.1021/acs.energyfuels.8b01887
ISSN: 0887-0624
Publisher: American Chemical Society
Start Page: 9159
End Page: 9171
Journal / Book Title: Energy and Fuels
Volume: 32
Issue: 9
Copyright Statement: © 2018 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/acs.energyfuels.8b01887
Sponsor/Funder: BP International Limited
Funder's Grant Number: 75195/ICAM15 (All)
Keywords: Science & Technology
Technology
Energy & Fuels
Engineering, Chemical
Engineering
QUARTZ-CRYSTAL MICROBALANCE
REFRACTIVE-INDEX MEASUREMENTS
CRUDE OILS
CAPILLARY-FLOW
SHEAR-FLOW
LIVE OILS
QCM-D
AGGREGATION
ADSORPTION
MODEL
03 Chemical Sciences
09 Engineering
Energy
Publication Status: Published
Appears in Collections:Faculty of Engineering
Mechanical Engineering



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