SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2015, Vol. 23 ›› Issue (6): 998-1008.DOI: 10.1016/j.cjche.2014.05.023

• 化工热力学 • 上一篇    下一篇

Thermodynamic design of a cascade refrigeration system of liquefied natural gas by applying mixed integer non-linear programming

Meysam Kamalinejad, Majid Amidpour, S.M. Mousavi Naeynian   

  1. Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran 1999143344, Iran
  • 收稿日期:2014-03-17 修回日期:2014-05-31 出版日期:2015-06-28 发布日期:2015-07-09
  • 通讯作者: Meysam Kamalinejad

Thermodynamic design of a cascade refrigeration system of liquefied natural gas by applying mixed integer non-linear programming

Meysam Kamalinejad, Majid Amidpour, S.M. Mousavi Naeynian   

  1. Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran 1999143344, Iran
  • Received:2014-03-17 Revised:2014-05-31 Online:2015-06-28 Published:2015-07-09
  • Contact: Meysam Kamalinejad

摘要: Liquefied natural gas (LNG) is the most economicalway of transporting natural gas (NG) over long distances. Liquefaction of NG using vapor compression refrigeration system requires high operating and capital cost. Due to lack of systematic design methods for multistage refrigeration cycles, conventional approaches to determine optimal cycle are largely trial-and-error. In this paper a novel mixed integer non-linear programming (MINLP) model is introduced to select optimal synthesis of refrigeration systems to reduce both operating and capital costs of an LNG plant. Better conceptual understanding of design improvement is illustrated on composite curve (CC) and exergetic grand composite curve (EGCC) of pinch analysis diagrams. In this method a superstructure representation of complex refrigeration system is developed to select and optimize key decision variables in refrigeration cycles (i.e. partition temperature, compression configuration, refrigeration features, refrigerant flow rate and economic trade-off). Based on this method a program (LNG-Pro) is developed which integrates VBA, Refprop and Excel MINLP Solver to automate the methodology. Design procedure is applied on a sample LNG plant to illustrate advantages of using this method which shows a 3.3% reduction in total shaft work consumption.

关键词: Cascade refrigeration cycle synthesis, Cryogenic, Liquefied natural gas, MINLP

Abstract: Liquefied natural gas (LNG) is the most economicalway of transporting natural gas (NG) over long distances. Liquefaction of NG using vapor compression refrigeration system requires high operating and capital cost. Due to lack of systematic design methods for multistage refrigeration cycles, conventional approaches to determine optimal cycle are largely trial-and-error. In this paper a novel mixed integer non-linear programming (MINLP) model is introduced to select optimal synthesis of refrigeration systems to reduce both operating and capital costs of an LNG plant. Better conceptual understanding of design improvement is illustrated on composite curve (CC) and exergetic grand composite curve (EGCC) of pinch analysis diagrams. In this method a superstructure representation of complex refrigeration system is developed to select and optimize key decision variables in refrigeration cycles (i.e. partition temperature, compression configuration, refrigeration features, refrigerant flow rate and economic trade-off). Based on this method a program (LNG-Pro) is developed which integrates VBA, Refprop and Excel MINLP Solver to automate the methodology. Design procedure is applied on a sample LNG plant to illustrate advantages of using this method which shows a 3.3% reduction in total shaft work consumption.

Key words: Cascade refrigeration cycle synthesis, Cryogenic, Liquefied natural gas, MINLP