A Theory Describing Asphaltene Adhesion Fouling Inside Heat Exchanger Tubes

Abstract

A theory for mathematically modeling asphaltene adhesion fouling in heat exchanger tubes was derived and its agreement with experiment suggested feasibility. The premise of this theory is that asphaltene adhesion fouling requires the formation of a chemical bond—modeled here as a sulfur–sulfur bond—which is strong enough to resist fluid dynamic forces. This theory suggests that once an asphaltene monolayer is adsorbed onto a heat transfer surface, shear stress alone may be insufficient for preventing further fouling unless the asphaltene flocculate size distribution can be manipulated, the chemically labile heteroatoms can be deactivated, or the asphaltenes can be kept in solution. A method for calculating fouling threshold shear stresses and flocculate diameters is expounded.

Acknowledgments

The author gratefully acknowledges Chevron for permission to publish this work. Discussions with Kevin Farrell of HTRI were very helpful and most appreciated. The critical reviews performed by Les Jackowski and Robert P. Hohmann of Chevron, Himanshu M. Joshi of Shell, and Grant Yokomizo of UOP were most enlightening and highly valued.