Study On The Liquefaction Process And Ratio Of Refrigerant Of The Medium And Small Scale Natural Gas Liquefaction Process

Liquefied natural gas is convenient for storage and transportation, so natural gas liquefaction technology arised the attention of the people. natural gas liquefaction industry has developed rapidly. Small and medium-sized natural gas liquefaction is an important part of the natural gas liquefaction industry.The study of small and medium liquefied natural process is of great significance for the development of small and medium-sized natural gas liquefaction industry. Researching on the key techniques of the small and medium-sized natural gas liquefaction,the main purpose of this article is to select a set of feasible and efficient liquefaction process for the small and medium-sized natural gas liquefaction plant.Comparing the advantages and disadvantages of the technology of desulphurization and decarbonization,dewatering,heavy hydrocarbon,the confirmed pretreatment method is MDEA decarbonization,molecular sieve dehydration of benzene.By hysys software for simulating mixed refrigerant liquefaction process,and analysis of the relationship between the parameters of the procession of high and low pressure refrigerant and the process performance parameters,the relationship between mixed refrigerant flow and the pinch point temperature difference,the relationship between the components of natural gas and refrigerant components which affect the heat transfer process,the best parameters of high and low pressure refrigerant and refrigerant components is choosed to optimize performance parameters of the liquefaction process.Using hysys of the Original model for mixed refrigerant liquefaction process and N₂-CH₄ expansion refrigeration liquefaction process optimization simulation and comparing the performance parameters of optimized mixed refrigerant liquefaction process and the expander liquefaction process,it is concluded the mixed refrigeration liquefaction cycle process is a kind of process which is suitable for small and medium-sized natural gas liquefaction process. Change the refrigerant components to improve the process,the ratio of mixed refrigerant in process: N₂:CH₄:C₂H₆:i-C₄H₁₀:C₂H₄=0.14:0.24:0.01:0.32:0.29.the high pressure refrigerant provide cold energy to the cold box after compression and cooling,the low-pressure and high-temperature refrigerant enters the compressor again after leaving the cold box and complete refrigeration cycle; the atural gas which is isolated from the gas after entering the cold box in the first time enter into the cold box again to greatly improve the process of liquefaction rate.