Aging is Important: Closing the Fouling–Cleaning Loop

Heat Transfer Engineering, Volume 35,  Issue 3, 2014
Special Issue:   In Celebration of Professor Hans Müller-Steinhagen on his 60th Birthday
Aging is Important: Closing the Fouling–Cleaning Loop
Edward M. Ishiyama (a), William R. Paterson (b) & D. Ian Wilson (b)
a IHS Downstream Research , London , United Kingdom
b Department of Chemical Engineering and Biotechnology , University of Cambridge , Cambridge , United Kingdom
Abstract
Process units subject to fouling often require regular cleaning, resulting in repeated cycles of fouling and cleaning. The initial stages of fouling are strongly influenced by the effectiveness of the most recent cleaning step. Similarly, the effectiveness and rate of cleaning are determined by the extent and nature of the deposit layer present on the surface. Consequently, the optimal operating cycle will be determined by fouling–cleaning interactions.
Because an aged deposit is more difficult to clean, deposit aging is an important factor in this. Aging provides an element of choice into fouling–cleaning operating cycles, between in situ “chemical” methods and ex situ “mechanical” methods, with associated differences in effectiveness, time, and cost. Authors report a reformulation of the cleaning scheduling problem to consider the choice of cleaning method, as well as the timing of cleaning. They present a case study based on a shell-and-tube heat exchanger processing crude oil to illustrate the concepts and scope of application of this approach.
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