Mitigation against crude oil wax solidification using TES fin

Significance 

Currently, crude oil is the major global energy resource whose reserves can be located either inland or in deep sea. During crude oil production in subsea conditions, several challenges are encountered where precipitation of wax from the crude oil is the most pronounced shortcoming globally, as it causes costly downtimes and its mitigation solutions are expensive. Paraffin wax formation is caused by low temperatures (around the crude oil container or pipe) that fall below the wax appearance temperatures thereby inducing solidification of paraffin components in the crude oil. Several solutions are commercially available but at exorbitant costs. Therefore, the prevention of the immobile wax formation for the ease of transportation in liquid phase becomes a daunting challenge.  Recent advances in thermal energy storage technology and lattice Boltzmann method have triggered intense research in this field. Unfortunately, most of the research work undertaken only focuses on other phase change materials excluding the most basic highly conductive metals, as part of the thermal energy storage medium. Furthermore, little has been done on metallic fins inserts as a thermal energy storage system to retard wax formation.

Dr. Yao Hong Yip, Professor Ai Kah Soh and Dr. Ji Jinn Foo at Monash University in Malaysia proposed a study on retardation of wax solidification using thermal energy storage fins. They hypothesized that a significant amount of thermal energy could be stored and dissipated through metallic components immediately after complete melting or heating process, that is, sensible-heat driven thermal energy storage-fins. They purposed to report on the numerical investigation of transient heat transfer in a solidifying paraffin wax contained in a bench-scale compartmented subsea storage tank with embedded thermal energy storage-fin(s). Their work is now published in the research journal, Chemical Engineering Research and Design.

Their studies involved employing the two-dimensional enthalpy-based lattice Boltzmann method that was capable of naturally capturing the innate propagation of mushy solid-liquid interface and explore the possibility of using thermal energy storage fins in reducing the paraffin solidification process within a storage tank. The research team observed the effects of cold wall cooling on compartment walls, selected adiabatic material as well as thermal energy storage-fin(s) positions and the corresponding aspect ratios to slow down paraffin solidification.

The authors also observed that their optimized thermal energy storage-fin configuration system was capable of prolonging paraffin solidification by 94% immediately after complete melting. Interestingly, they noted that the mushy interface zone propagation rate during the paraffin wax solidification was reduced to a minimum, once the dimensionless length-to-width aspect ratio of thermal energy storage-fin approached 1.15 and most importantly, it was seen to be strongly position dependent.

Monash University researchers has successfully employed a direct model that utilizes the lattice Boltzmann technique to investigate the possibility of retarding paraffin wax solidification process, as a natural manifestation of changes in local enthalpy states within a compartmented stainless steel enclosure induced by thermal energy storage metallic fin(s). The presented findings may serve as guidance for the long-term sustainable development in addressing the existing logistic issues on sustainable crude oil shipment from oil platforms.

Mitigation against crude oil wax solidification using TES fin. Advances in Engineering

Temperature distribution of a composite system for a TES fin made up of (a-d) bare aluminum and (e-h) aluminum with an insulation of thickness Δx/lcprt,x = 0.038. Horizontal and vertical axes start from x* = 0.2 and y* = 0.5 respectively, in order to accentuate the thermal energy transfer within the TES fin in which the top and bottom halves are symmetrical.

About the author

Ji Jinn Foo was born in Melaka, Malaysia. He received his BS and MS in Mechanical Engineering from National Chung Cheng University (Taiwan) in 1998 and 2000, respectively; and PhD in Mechanical Engineering from Nanyang Technological University, Singapore (2004). He was a Postdoctoral Fellow at Max Planck Institute of Molecular Cell Biology and Genetic (MPI-CBG, Dresden, Germany) from 2004 to 2008. In 2004, he returned to Malaysia and joined SEGi University to start his academic career. In 2012, he became an Associate Professor and the Director of Research & Innovation Management Centre (RIMC) of the same university. He then left SEGi University to join Monash University Malaysia as a Senior Lecturer of Mechanical Engineering since 2013.

His research mainly focuses on the attempts to work on a novel heat transfer method, i.e. to employ insert(s)-induced fluid flow perturbation as a mean of thermal dissipation via forced convective or natural convective heat transfer.

About the author

A.K. Soh started his academic career in 1983 at Nanyang Technological University (NTU), Singapore; and he left NTU in August 1996 to join the Department of Mechanical Engineering, The University of Hong Kong (HKU). He was promoted to Full Professor in 2003, and he served as an Associate Dean in the Faculty of Engineering, HKU, from 2007 – 2009. He left HKU in March 2013 to join Monash University (Sunway Campus) as the Head and Professor of Mechanical engineering.

He has been pursuing research in Advanced Functional Materials since 1999. To-date, he had won more than US$3 million competitive research funding for studying advanced functional materials. He has published more than 260 ISI journal papers. He has collaborated with world renowned researchers in Brown University, Washington University, National University of Singapore, Peking University, Tsinghua University, and National Taiwan University.

About the author

Dr. Yip, Yao Hong received his B.Eng. and Ph.D. degrees in Chemical and Mechanical Engineering, both from Monash University Malaysia. His research primarily addressed thermal induced phase change of crude oil paraffin wax using the lattice Boltzmann method (LBM). He incorporated the momentum population in LBM to study flow dynamics within melt zone of a phase change material under the influence of natural convection. His work was featured in the APCChE 2015 Congress incorporating Chemeca International Conference. Applications of his study were extended to mitigation and control of solidification as well as enhancement of melting via thermal management and flow dynamic reconstruction.

His work also involved improving numerical stability within multi-population LBM models, as well as assessing numerical accuracy and enhancing computational performance. His research interests are focused on heat transfer, thermal science, phase change, natural convection, and mesoscopic modeling. Recently, he is exploring new flow reconstruction techniques for natural convective melting using flow inserts and passive mixers.

Reference

Yao Hong Yip, Ai Kah Soh, Ji Jinn Foo. Mitigation against crude oil wax solidification using TES fin. chemical engineering research and design, volume 126 (2017) pages 172–187

 

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