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Polley G.T.,University of Guanajuato | Fuentes A.M.,University of Guanajuato | Pugh S.J.,IHS ESDU
Heat Transfer Engineering | Year: 2011

Fouling dominates the design of heat exchangers used in crude oil preheat trains. It also dominates the lifetime cost of the trains, where the most important cost factor is lost profit through reduced production. Thus, the design objective should be the identification of geometries that provide acceptable performance throughout a desired operating period. This paper suggests a new design approach for shell-and-tube heat exchangers in refinery preheat trains that uses dynamic crude oil fouling models rather than conventional fouling factors to yield designs that are capable of achieving a specified operating period between cleaning operations. Copyright © Taylor and Francis Group, LLC.

Macchietto S.,Imperial College London | Hewitt G.F.,Imperial College London | Coletti F.,Imperial College London | Crittenden B.D.,University of Bath | And 13 more authors.
Heat Transfer Engineering | Year: 2011

A major cause of refinery energy inefficiency is fouling in preheat trains. This has been a most challenging problem for decades, due to limited fundamental understanding of its causes, deposition mechanisms, deposit composition, and impacts on design/operations. Current heat exchanger design methodologies mostly just allow for fouling, rather than fundamentally preventing it. To address this problem in a systematic way, a large-scale interdisciplinary research project, CROF (crude oil fouling), brought together leading experts from the University of Bath, University of Cambridge, and Imperial College London and, through IHS ESDU, industry. The research, coordinated in eight subprojects blending theory, experiments, and modeling work, tackles fouling issues across all scales, from molecular to the process unit to the overall heat exchanger network, in an integrated way. To make the outcomes of the project relevant and transferable to industry, the research team is working closely with experts from many world leading oil companies. The systematic approach of the CROF project is presented. Individual subprojects are outlined, together with how they work together. Initial results are presented, indicating that a quantum progress can be achieved from such a fundamental, integrated approach. Some preliminary indications with respect to impact on industrial practice are discussed. Copyright © Taylor and Francis Group, LLC.

Walker S.K.,Jesmond Engineering Ltd | Quilter A.C.,IHS ESDU
ICAF 2011 Structural Integrity: Influence of Efficiency and Green Imperatives - Proceedings of the 26th Symposium of the International Committee on Aeronautical Fatigue | Year: 2011

IHS ESDU decided to approach a number of organisations in order to compile a reference source of cyclic stress-strain and strain-life properties for the benefit of the wider aerospace industry. Work began in 2006 on the collection and collation of the raw data points for commonly-used aerospace metallic materials. Beside the data available in the literature and other readily-accessible sources, efforts were made to encourage organisations with their own data to contribute to a database from which they would subsequently benefit. Considerable support and enthusiasm were expressed for the project and generous donations of data were received from a number of organisations. These data were combined with those gathered from public domain sources and those considered to be the most robust were retained. Cyclic stress-strain curves fitted using the Ramberg-Osgood equation were found to correlate well with the test data. The Coffin-Manson strain-life model was generally less successful but curves are provided due to their widespread use. The resulting set of cyclic stress-strain and strain-life properties of commonly-used aerospace metallic materials permits a wider appreciation of material fatigue behaviour not previously available. The results are to be published in forthcoming IHS ESDU Data Item Number 11003. Analysis of specimen geometries led to some simple design recommendations that may be useful to those considering future strain-controlled testing.

Polley G.T.,University of Guanajuato | Polley G.T.,Loughborough University | Vidal Farfan M.A.,University of Guanajuato | Pugh S.J.,IHS ESDU
Chemical Engineering | Year: 2012

Identification of geometry that avoids dangerous vibration can be undertaken as an integral part of the design process. The technique is based on a plot method for heat exchanger design that is easily adapted to handle tube-bundle vibration analysis and thermal design simultaneously. This so-called parameter plot approach to heat exchanger design allows the engineer to identify a design space providing geometry that satisfies both the required thermal duty and observes the pressure drop constraints. The design space has two axes, tube length and tube count. Using this plot, one can quickly evaluate the effects of changing bundle layout, baffle arrangement and tube pass arrangement on the design space. The parameter plot is a powerful graphic that provides the designer with understanding of the factors controlling the design. Generation of the plot involves systematically working along the tube count axis.

Polley G.T.,University of Guanajuato | Wilson D.I.,University of Cambridge | Ishiyama E.,IHS ESDU
11AIChE - 2011 AIChE Spring Meeting and 7th Global Congress on Process Safety, Conference Proceedings | Year: 2011

The rate at which an exchanger heating crude oil fouls increases with increasing wall temperature and decreases with increasing velocity. Fouling can be mitigated by reducing wall temperatures and by increasing wall shear. These actions can be achieved by making changes to the heat exchanger or by adjusting the conditions under which the exchanger operates. A discussion on mitigating fouling in pre-heat trains covers the modeling of heat exchangers forming a pre-heat train to identify ways in which fouling in individual exchangers can be reduced; operating conditions of individual units; design margin specifications; the no-fouling design; variables influencing the wall and film temperatures encountered in a heat exchanger; and evaluating changes in train performance using thermal-hydraulic simulation. This is an abstract of a paper presented at the 2011 AIChE Spring Meeting & 7th Global Congress on Process Safety (Chicago, IL 3/13-17/2011).

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