基于反应分子动力学的超临界多元热流体发生规律及物性变化特征

Generation and variation characteristics of supercritical multicomponent thermal fluids based on reaction molecular dynamics simulation

摘要

超临界多元热流体发生过程中各组分质量分数变化规律认识不清。基于反应分子动力学方法，进行不同条件下的超临界多元热流体发生规律模拟，结合实验和模型计算结果，研究热流体各组分质量分数随反应温度、反应压力、时间和原料比例的变化规律，分析热流体各组分质量分数变化对流体物性的影响。结果表明：模拟结果与相近条件的实验和理论计算结果吻合度较高，采用反应分子动力学模拟研究超临界多元热流体发生规律具有较高准确性；反应温度、反应压力越高，原料完全反应时间越短；柴油质量分数越高，原料完全反应时间越长；反应温度、压力对完全反应后超临界多元热流体各组分质量分数无显著影响，柴油质量分数影响较大，柴油质量分数越高，热流体中二氧化碳和氮气质量分数越高，水质量分数越低；在反应未完全时，反应时间对热流体物性的影响较显著，反应初始至结束的流体密度降幅为 8.19% ，流体比焓降幅为 49.85% ，在反应完全后，反应原料比例对热流体物性影响较大，原料柴油质量分数由 8.39% 上升至 25.14% ，流体密度增幅为 7.82% ，流体比焓降幅为 10.58% 。该结果为开展超临界多元热流体发生规律研究及热流体发生环境优化提供参考。

Abstract

The changing rule of the supercritical multicomponent thermal fluid components' content during its generation process need to be further studied, and there are some shortcomings and difficulties to explore this project through the experimental and theoretical methods. Therefore, reaction molecular dynamics simulation is used to study the supercritical multicomponent thermal fluid generation process under different reaction conditions. And the simulation results are compared with physical experiment results and theoretical calculation results to demonstrate the feasibility of using reaction molecular dynamics theory to study the generation characteristics of supercritical multicomponent thermal fluids. Meanwhile, the variation law of each component content of thermal fluid with reaction temperature, reaction pressure, reaction time and reaction raw material ratio is preliminarily studied. Based on the simulation results, the influence of the change of thermal fluids component content on the physical properties is analyzed. Results show that the simulation results of reaction molecular dynamics are in good agreement with laboratory experiments and theoretical calculation results under similar conditions. The method of reaction molecular dynamics simulation is accurate and representative in studying the generation characteristics of supercritical multicomponent thermal fluids. Higher temperature and pressure will bring a faster full reaction state, and higher diesel mass concentration will bring a slower result. Reaction temperature and pressure have no significant influence on the mass concentration of each component of supercritical multicomponent thermal fluids after complete reaction. However, the diesel mass concentration has a greater impact on it, higher diesel concentration can lead to the increase content of carbon dioxide and nitrogen, and the decrease content of water. When the reaction time in the reaction is not complete, there is a significant effect on the physical properties of thermal fluid, the initial reaction to the end of the reaction fluid density drop of 8.19%, the specific enthalpy of the fluid drop of 49.85%, and the proportion of the reaction feedstock in the complete reaction of the physical properties of the thermal fluid has a greater impact on the raw material, raw material diesel fuel concentration from 8.39% to 25.14%, the increase in the density of the fluid increased by 7.82%, the specific enthalpy of the fluid dropped by 10.58%. The research results provide a reference for further research on the generation characteristics and thermal fluid generation environment optimization.

关键词

超临界多元热流体 / 发生规律 / 热流体物性 / ReaxFF 反应力场 / 分子动力学模拟 / 稠油热采

Key words

supercritical multicomponent thermal fluids / generation characteristics / thermal fluids physical properties / ReaxFF reaction force field / molecular dynamics simulation / heavy oil thermal recovery

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基金资助

国家自然科学基金重点支持项目(U22B2074)

中海石油（中国）有限公司北京研究中心重点技术攻关项目(CCL2023RCPS0077RSN)

中央支持地方高校改革发展资金人才培养项目(黑财教〔2021〕137号)