管道封堵水凝胶设计及特性仿真
学科：机械工程
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常期高负荷和恶劣的使用环境致使长距离油气管道输送管道发生泄漏与爆炸等重大安全事故。管道封堵技术是解决管道更换与维修的核心技术，传统的机械封堵技术配套设备繁重，工序复杂，难以快速完成恶劣工况环境下管道封堵。基于高分子材料的高强度、可降解且合成可控性等特点，提出采用水凝胶进行管道封堵的方式。然而，高分子聚合反应过程复杂，受反应单体种类，反应条件等多种不确定因素的影响。试验研究过程耗时长，可控性差。为了缩短试验周期，降低试验成本，本文采用MC分子模拟方法对聚合过程进行研究，为封堵水凝胶的设计提供理论基础并通过模拟结果进一步指导试验的设计。
在643立方格中，建立了聚合反应模型，进行了聚合反应过程的MC模拟。结果表明在该聚合反应模型
下，链段长度分布、链段分子数量、链段平均长度以及数均聚合度的模拟结果与经典Flory缩聚理论具有较高的吻合度。当聚合单体反应活性相似时，通过改变聚合单体的投料比，模拟结果也与理论结果吻合度较高，说明了模拟过程模型符合二级反应理论特征，进一步验证了聚合反应模型的正确性。
针对试验单体选型、投料比及温度的试验参数设计问题，通过聚合反应模型，模拟了等投料比情况下，不同单体活性对聚合反应中分子链长度等因素的影响。结果表明，加入的单体活性等于或高于基础单体活性时，分子链段长度有所增加，但活性过高时则难形成高分子网状结构。在共聚单体活性相同时，模拟了不同温度下，投料比对聚合产物结晶的影响。结果表明，当两单体的投料比相差较大时，微量单体主要以游离分散方式镶嵌在主链上，当投
料比相差逐渐缩小时，共聚单体抑制了晶体成核及生长，更容易获得具有更高聚合度的产物，从而提高其宏观力学特性。当聚合反应反应温度较低时，链段短的分子链快速形成低聚物并发生结晶，从而限制了高分子量凝胶结构的形成。而温度较高时，形成高分子量凝胶结构的速度较慢。
针对水凝胶在管道中复杂的流动性问题，通过C语言编写了不可压缩粘弹性流体的管道流动模拟过程。基于现有的ALE自由面追踪技术与迭代分步算法，模拟了粘弹性流体在“Z”型管道中的流动。结果表明，模拟中网格的生成均未出现畸形网格，不同时间水凝胶压力云图与试验相符。
为了获得具有高强度的高分子水凝胶，基于单体活性，投料比以及温度的聚合模拟结果，选择以丙烯
酰胺为基础单体，通过改变丙烯酸与丙烯酰胺的投料比与聚合反应温度，设计了单体投料比为AM:AA=5:1，聚合反应温度为25℃，50℃单因素试验。结果表明，反应温度为50℃时，水凝胶承压能力最高，承压值为45N。在此基础上，进一步设计了聚合温度为50℃时，丙烯酰胺与丙烯酸投料比分别为5:1，3:1，1:1的单因素。结果表明，反应温度为50℃，投料比1:1时，能获得承压性能为55N的水凝胶。并选择这组最优组进行模拟工程管道承压封堵。结果表明，最优组水凝胶完成了管道内径为190mm，长为1000mm模拟工程管道封堵，承压值为0.2Mpa，封堵时间为12h。
关键词：水凝胶；化学封堵；分子模拟；高强度；承压能力宋玉简介
Design and Characteristic Simulation of Pipeline Sealing Hydrogel Discipline:Mechanical engineering
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Abstract
Long-distance oil and gas pipeline leakage and explosion and other major safety incidents are caud by high load and harsh u environment.Pipeline plugging technology is the core technology to solve the problem of pipeline replacement and maintenance.Traditional mechanical plugging technology has heavy equipment and complex process,which makes it difficult to quickly complete pipeline plugging under harsh working conditions.Bad on the characteristics of high strength,biodegradability and controllability of synthesis of polymer materials,we propo to u polymer materials for pipeline plugging.However,the process of polymer polymerization is complex,which is affected by many uncertainties such as the types of monomers and reaction conditions.The experimental rearch process takes a long time and has poor controllability.MC mol
ecular simulation software was ud to study the polymerization process,and the simulation results were ud to further guide the design of the experiment.
the model of polymerization was established and the molecular dynamics simulation of the polymerization process was carried out.The results show that the simulation results of the length distribution,the number of chain molecules,the average length of chain gments and the degree of number-average polymerization are in good agreement with the classical Flory polycondensation theory.When the reactivity of the monomers is similar,the simulation results are in good agreement with the theoretical results by changing the feed ratio of the monomers.It shows that the simulation process model accords with the characteristics of the cond-order reaction theory,and further verifies the correctness of the polymerization model.
Aiming at the lection of experimental monomers,the ratio of feeding materials and the design of temperature experimental parameters.The effects of different monomer activities on the
length of molecular chains in the process of polymerization were simulated by using the model of polymerization.The results show that when the activity of the added monomer is equal to or higher than that of the basic monomer,the length of the molecular chain increas,but when the activity is to
o high,it is difficult to form a polymer network structure.When the activity of the copolymer was the same,the crystallization of the copolymer was simulated at different temperatures.The results show that when the feed ratio of the two monomers is quite different,we find that the micro-monomers are mosaic in the main chain in the form of free dispersion,so the micro-copolymerization has little effect on the main chain quence.The morphology of micelles formed by copolymers in solvents is influenced by the content of copolymer units and the quence structure.
Aiming at the complex rheological problem of hydrogel in pipeline,we compiled the flow simulation process of incompressible viscoelastic fluid in pipeline by C language.Bad on ALE free surface tracing technique and iterative step-by-step algorithm,we simulated the flow of viscoelastic fluid in"Z"pipe.The results show that no deformed meshes appear in the simulation.
两头忙>坚毅的眼神In order to obtain high strength polymer hydrogels.Bad on the simulation results of monomer activity,feed ratio and temperature,we cho acrylamide as the basic monomer.By changing the feed ratio of acrylic acid and acrylamide and the reaction temperature,we designed a single factor experiment of monomer feed ratio AM:AA=5:1,the reaction temperature was25℃, 50℃.The results show that the hydrogel has a higher pressure-bearing capacity at50℃,and the pressure-bearing value is45N.Furthermore,a single factor of5:1,3:1and1:1for acrylamide and acrylic acid was designe
d when the polymerization temperature was50℃.The results show that the hydrogel with pressure-bearing property of55N can be obtained at the reaction temperature of 50℃and the feed ratio of1:1.The optimal group is lected to simulate the pressure-bearing plugging of pipelines.The results show that the optimal group of hydrogels completes the pipeline plugging with190mm inner diameter and1000mm length.The pressure value is0.2Mpa,the plugging time is12hours.
什么叫因式分解
鲫鱼汤Key Words:hydrogel;chemical plugging;molecular simulation;high strength;pressure bearing capacity
