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Heat Exchanger Fouling and Cleaning VII
July 1-6, 2007 - Tomar, Portugal
| Editors: |
Hans Müller-Steinhagen, Institute of Technical Thermodynamics, German Aerospace Centre (DLR)
and Institute for Thermodynamics and Thermal Engineering, University of Stuttgart, Germany
M. Reza Malayeri, University of Stuttgart, Germany
A. Paul Watkinson, The University of British Columbia, Canada |
The articles for these proceedings are peer-reviewed.
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PRECIPITATION AND FOULING IN HEAVY OIL–DILUENT BLENDS
E Hong, State Key Laboratory of Heavy Oil Processing, Faculty of Chemical Science and Engineering, China University of Petroleum (Beijing)
A. Paul Watkinson, Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, B. C., Canada V6T 1Z3
ABSTRACT:
Heavy oil fractions rich in asphaltenes were mixed with
diluents containing from 0.6-25% aromatics, and the
resulting blends subjected to batch precipitation
experiments at 85°C, and thermal fouling tests at surface
temperatures in the range 230-310ºC. Deposit
compositions were determined, and are compared with
suspended asphaltene composition. When the heavy oils
were blended with the most aromatic diluents,
precipitation and fouling were negligible. As the
aromaticity of the diluents was decreased, the extent of
asphaltene precipitation and the fouling rates increased.
The solubility parameter of the blends, δmix, and the
flocculation solubility parameter for asphaltenes, δf , were
determined from measurements of the asphaltene
flocculation onset by titration with heptane at
temperatures from 25 to 50°C. Literature models predict
no asphaltene precipitation (and presumably little fouling)
will occur when [δmix- δf ] >0 . Both the amount of
asphaltene precipitated in the batch experiments, and the
rate of thermal fouling decreased as the solubility
parameter difference [δmix - δf] increased from negative to
positive values. However some precipitation and fouling
was observed at the expected condition for mixture
stability δmix ≥ δf . As the temperature of the flocculation
titration was raised towards the bulk temperatures of the
experiments, values of [δmix-δf] decreased, and the
agreement of the data with prediction of the point for zero
precipitation and fouling improved. For unstable oil
blends, the solubility parameter provides a good
predictive measure of the tendency for asphaltene
precipitation, and for heat exchanger fouling.
E Hong and A. Paul Watkinson, "PRECIPITATION AND FOULING IN HEAVY OIL–DILUENT BLENDS" in "Heat Exchanger Fouling and Cleaning VII", Hans Müller-Steinhagen, Institute of Technical Thermodynamics, German Aerospace Centre (DLR)
and Institute for Thermodynamics and Thermal Engineering, University of Stuttgart, Germany
M. Reza Malayeri, University of Stuttgart, Germany
A. Paul Watkinson, The University of British Columbia, Canada
Eds, ECI
Symposium Series, Volume RP5 (2007). http://services.bepress.com/eci/heatexchanger2007/6
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