Liquefied natural gas(LNG) is the most economical way of transporting natural gas(NG) over long distances. Liquefaction of NG using vapor compression refrigeration system requires high operating and capital cost. Due ...Liquefied natural gas(LNG) is the most economical way 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.展开更多
With increasing consumption of natural gas(NG),small NG reservoirs,such as coalbed methane and oil field associated gas,have recently drawn significant attention.Owing to their special characteristics(e.g.,scattered d...With increasing consumption of natural gas(NG),small NG reservoirs,such as coalbed methane and oil field associated gas,have recently drawn significant attention.Owing to their special characteristics(e.g.,scattered distribution and small output),small-scale NG liquefiers are highly required.Similarly,the mixed refrigerant cycle(MRC)is suitable for small-scale liquefaction systems due to its moderate complexity and power consumption.In consideration of the above,this paper reviews the development of mobile miniature NG liquefiers in Technical Institute of Physics and Chemistry(TIPC),China.To effectively liquefy the scattered NG and overcome the drawbacks of existing technologies,three main improvements,i.e.,low-pressure MRC process driven by oil-lubricated screw compressor,compact cold box with the new designed heat exchangers,and standardized equipment manufacturing and integrated process technology have been made.The development pattern of"rapid cluster application and flexible liquefaction center"has been eventually proposed.The small-scale NG liquefier developed by TIPC has reached a minimum liquefaction power consumption of about 0.35 kW.h/Nm^(3).It is suitable to exploit small remote gas reserves which can also be used in boil-off gas reliquefaction and distributed peak-shaving of pipe networks.展开更多
文摘Liquefied natural gas(LNG) is the most economical way 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.
基金the National Natural Sciences Foundation of China(Grant Nos.51625603 and 51876215)the International Partnership Program of the Chinese Academy of Sciences(Grant No.GJHZ1876).
文摘With increasing consumption of natural gas(NG),small NG reservoirs,such as coalbed methane and oil field associated gas,have recently drawn significant attention.Owing to their special characteristics(e.g.,scattered distribution and small output),small-scale NG liquefiers are highly required.Similarly,the mixed refrigerant cycle(MRC)is suitable for small-scale liquefaction systems due to its moderate complexity and power consumption.In consideration of the above,this paper reviews the development of mobile miniature NG liquefiers in Technical Institute of Physics and Chemistry(TIPC),China.To effectively liquefy the scattered NG and overcome the drawbacks of existing technologies,three main improvements,i.e.,low-pressure MRC process driven by oil-lubricated screw compressor,compact cold box with the new designed heat exchangers,and standardized equipment manufacturing and integrated process technology have been made.The development pattern of"rapid cluster application and flexible liquefaction center"has been eventually proposed.The small-scale NG liquefier developed by TIPC has reached a minimum liquefaction power consumption of about 0.35 kW.h/Nm^(3).It is suitable to exploit small remote gas reserves which can also be used in boil-off gas reliquefaction and distributed peak-shaving of pipe networks.
