Thermodynamic and economic optimization of LNG mixed refrigerant processes

Mengyu Wang, Rajab Khalilpour, Ali Abbas

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Natural gas liquefaction processes are energy and cost intensive. This paper performs thermodynamic and economic optimization of the mid-scale mixed refrigerant cycles including propane precooled mixed refrigerant (C3MR) and dual mixed refrigerant (DMR) processes. Four different objective functions in this study are selected: total shaft work consumption, total cost investment (TCI), total annualized cost (TAC), and total capital cost of compressors and main cryogenic exchangers (MCHEs). Total cost investment (TCI) is a function of two key variables: shaft work (W) and overall heat transfer coefficient and area (UA) of MCHEs. It is proposed for reducing energy consumption and simultaneously minimizing total capital expenditure (CAPEX) and operating expenditure (OPEX). Total shaft work objective function can result in a 44.5% reduction of shaft work for C3MR and a 48.6% reduction for DMR compared to their baseline values, but infinitely high UA of MCHEs. Optimal results show that total capital cost of compressors and MCHEs is more suitable than other objective functions for the objective of reducing both shaft work and UA. It reduces 14.5% of specific power for C3MR and 26.7% for DMR when achieving the relatively lower UA values than their baseline values. In addition, TCI and TAC can also reduce a certain amount of total shaft work at a finite increased UA.

Original languageEnglish
Pages (from-to)947-961
Number of pages15
JournalEnergy Conversion and Management
Volume88
DOIs
Publication statusPublished - 2014
Externally publishedYes

Keywords

  • CAPEX
  • Exergy
  • LNG
  • Mixed refrigerant
  • OPEX
  • Optimization

Cite this

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title = "Thermodynamic and economic optimization of LNG mixed refrigerant processes",
abstract = "Natural gas liquefaction processes are energy and cost intensive. This paper performs thermodynamic and economic optimization of the mid-scale mixed refrigerant cycles including propane precooled mixed refrigerant (C3MR) and dual mixed refrigerant (DMR) processes. Four different objective functions in this study are selected: total shaft work consumption, total cost investment (TCI), total annualized cost (TAC), and total capital cost of compressors and main cryogenic exchangers (MCHEs). Total cost investment (TCI) is a function of two key variables: shaft work (W) and overall heat transfer coefficient and area (UA) of MCHEs. It is proposed for reducing energy consumption and simultaneously minimizing total capital expenditure (CAPEX) and operating expenditure (OPEX). Total shaft work objective function can result in a 44.5{\%} reduction of shaft work for C3MR and a 48.6{\%} reduction for DMR compared to their baseline values, but infinitely high UA of MCHEs. Optimal results show that total capital cost of compressors and MCHEs is more suitable than other objective functions for the objective of reducing both shaft work and UA. It reduces 14.5{\%} of specific power for C3MR and 26.7{\%} for DMR when achieving the relatively lower UA values than their baseline values. In addition, TCI and TAC can also reduce a certain amount of total shaft work at a finite increased UA.",
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Thermodynamic and economic optimization of LNG mixed refrigerant processes. / Wang, Mengyu; Khalilpour, Rajab; Abbas, Ali.

In: Energy Conversion and Management, Vol. 88, 2014, p. 947-961.

Research output: Contribution to journalArticleResearchpeer-review

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