Simulation of Dual Mixed Refrigerant Natural Gas Liquefaction Processes Using a Nonsmooth Framework

Natural gas liquefaction is an energy intensive process where the feed is cooled from ambient temperature down to cryogenic temperatures. Different liquefaction cycles exist depending on the application, with dual mixed refrigerant processes normally considered for the large-scale production of Liqu...

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Bibliographic Details
Main Authors: Vikse, Matias (Author), Gundersen, Truls (Author), Watson, Harry Alexander James (Contributor), Barton, Paul I (Contributor)
Other Authors: Massachusetts Institute of Technology. Department of Chemical Engineering (Contributor), Massachusetts Institute of Technology. Process Systems Engineering Laboratory (Contributor)
Format: Article
Language:English
Published: MDPI AG, 2018-11-05T20:19:23Z.
Subjects:
Online Access:Get fulltext
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100 1 0 |a Vikse, Matias  |e author 
100 1 0 |a Massachusetts Institute of Technology. Department of Chemical Engineering  |e contributor 
100 1 0 |a Massachusetts Institute of Technology. Process Systems Engineering Laboratory  |e contributor 
100 1 0 |a Watson, Harry Alexander James  |e contributor 
100 1 0 |a Barton, Paul I  |e contributor 
700 1 0 |a Gundersen, Truls  |e author 
700 1 0 |a Watson, Harry Alexander James  |e author 
700 1 0 |a Barton, Paul I  |e author 
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520 |a Natural gas liquefaction is an energy intensive process where the feed is cooled from ambient temperature down to cryogenic temperatures. Different liquefaction cycles exist depending on the application, with dual mixed refrigerant processes normally considered for the large-scale production of Liquefied Natural Gas (LNG). Large temperature spans and small temperature differences in the heat exchangers make the liquefaction processes difficult to analyze. Exergetic losses from irreversible heat transfer increase exponentially with a decreasing temperature at subambient conditions. Consequently, an accurate and robust simulation tool is paramount to allow designers to make correct design decisions. However, conventional process simulators, such as Aspen Plus, suffer from significant drawbacks when modeling multistream heat exchangers. In particular, no rigorous checks exist to prevent temperature crossovers. Limited degrees of freedom and the inability to solve for stream variables other than outlet temperatures also makes such tools inflexible to use, often requiring the user to resort to a manual iterative procedure to obtain a feasible solution. In this article, a nonsmooth, multistream heat exchanger model is used to develop a simulation tool for two different dual mixed refrigerant processes. Case studies are presented for which Aspen Plus fails to obtain thermodynamically feasible solutions. Keywords: nonsmooth modeling; process simulation; DMR liquefaction processes 
655 7 |a Article 
773 |t Processes