Research On Cryogenic Properties And Quality Optimization Of LNG

With the enhancement of human environmental awareness,natural gas as clean energy has been widely used in many fields such as urban gas,metallurgy,electronics,power generation,and chemical raw materials.After comparing and analyzing the LNG components and their main performance in different regions at home and abroad,it has been found that the LNG components varies from different regions,and even shows some great differences.At the same time,LNG has different quality requirements in different fields.In order to meet the demands of various fields,increase economic efficiency and avoid energy waste,LNG quality can be optimized by adjusting the content of LNG components.LNG quality relates to the special requirements of users in various fields such as gas supply stability,safety,gas calorific value and composition.To carry out the research on cryogenic properties and quality optimization of LNG,this project applied the mechanism of cryogenic liquid miscible mixing to the LNG quality adjustment and used the ejection mixer to optimize the LNG quality.FLUENT software was used to analyze the influence of structural parameters and operating parameters of the ejection mixer on its mixing performance,and the distribution of the flow field of the ejection mixer was obtained.Based on the similarity principle,the internal flow field distribution and mixing performance of the small ejection mixer are studied,and compared with the internal flow field distribution of the actual ejection mixer.The main research work and conclusions are as follows:(1)Feasibility analysis of LNG quality optimization method.Based on the miscible mixing mechanism of cryogenic liquids,it is feasible to calculate the solubility parameters,dielectric constants,and Gibbs free energy change of each component to obtain a method for adjusting the content of LNG components to achieve their quality optimization.(2)Effect of structural parameters on mixing performance of ejection mixer.An internal fluid model of the ejection mixer is established with liquid methane and liquid propane as the working fluid.A numerical simulation,using analysis software FLUENT,is performed to gain the distribution of the flow field in different suction angle and nozzle diameter ejection mixer and to obtain the effects of different suction angle and nozzle diameter of the ejecti on performance mixer.(3)Effect of operating parameters on ejection mixing performance of ejection mixer.Based on the ejection mixer of optimizing structural parameters,the internal fluid model of the liquid methane and liquid propane ejection mixer is established.The flow field of the ejection mixer with different operating parameters is simulated and analyzed,and The influence of the primary fluid inlet pressure,ejection fluid inlet pressure,the inlet temperature of the ejection fluid and the outlet pressure of the mixed fluid on the mixing performance of the ejection mixer are obtained.Synthesizing each kind of situation,the optimal operating parameters of the ejection mixer are confirmed within the scope of the study.(4)Research on small experiment ejection mixer Based on the similarity theory,the experiment ejection mixer is studied to obtain the distribution and mixing performance of the flow field in the small ejection mixing test system,and compared with the distribution and mixing performance of the flow field in the actual ejection mixer.The results showed that: the distribution of the flow field in thel ejection mixer and the actual ejection mixer is similar,and it is feasible to use the similarity theory to guide the research of the ejection mixer.