LNG Light Hydrocarbon Recovery And Cold Energy Utilization Process Optimization

With the continuous adjustment of China’s energy structure,LNG has become one of the most concerning energy sources in the 21st century.LNG contains a certain amount of C₂⁺light hydrocarbons,which will not only cause waste of resources but also create safety hazards for natural gas pipelines if it is directly fed to users.Therefore,in this paper,the LNG light hydrocarbon recovery process is studied from the perspective of the recovery of C₂⁺light hydrocarbons.Combining with the current status of LNG light hydrocarbon recovery research at home and abroad,the new LNG light hydrocarbon recovery process is proposed by analyzing the process analysis,performance analysis,wicket analysis,and advantages and disadvantages of five existing classical light hydrocarbon recovery processes at home and abroad.And a sensitivity analysis is also conducted on the LNG light hydrocarbon recovery process of this paper,analyzing the influence of process parameters on process performance(methane substance fraction,ethane recovery rate,energy consumption per unit C₃⁺and cold energy utilization.The optimal process parameters were determined as flash tower inlet temperature-105℃,de-methane tower top pressure 2800 k Pa,de-methane tower theoretical tower plate number 14 layers,de-ethane tower top pressure 1700 k Pa,and de-ethane tower theoretical tower plate number 6 layers,and then the LNG light hydrocarbon recovery process was simulated in this paper.Dry ice production is the second stage of cold energy utilization,and the CO₂ feed rate is 10 t/h,which can obtain 5.4 t/h of dry ice.Through the performance analysis and economic analysis of six LNG light hydrocarbon recovery processes,it is found that the process in this paper has certain advantages in terms of C₂⁺light hydrocarbon recovery rate,system breakdown analysis,energy consumption per unit of light hydrocarbon,cold energy utilization rate,annual net profit（after tax）,investment return,and payback period.