共查询到19条相似文献,搜索用时 187 毫秒
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热油管道计划检修和事故抢修都在管道停输情况下进行,管道停输后,管内存油温度不断下降,存油粘度随油温下降而增大,当粘度增大到一定值后,就会给管道输送再启动带来极大困难,甚至会造成凝管事故。为了确保安全经济的输油,必须研究停输后管内原油的温降情况,以确定安全停输时间。本文分析了埋地含蜡原油管道停输后管内原油温降规律,在前人研究的基础上,对埋地含蜡原油管道停输温降过程进行了合理的简化,建立了相应的数学模型。在此基础上,运用计算程序,对中洛线卫辉-新乡段管道稳态运行及停输不同时间时,管道不同横截面上原油与土壤温度变化情况进行了模拟计算,从不同角度对计算结果进行了分析。 相似文献
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原油在管道输送的过程中不可避免会出现停输现象。针对原油管道停输再启动存在的技术难题。以热力水力分析为基础,应用仿真模拟的方法利用Pipeline Studio(TLNET)软件模拟管道停输温降过程。以庆哈管道为例,模拟管道停输温降过程,根据模拟结果绘制了三维温降图,以原油凝固点以上3℃为判据确定了安全停输时间。最终确定庆哈输油管道冬季安全停输时间为24 h,为管道安全运行提供了可靠的理论依据。 相似文献
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水分迁移冰水相变对冻土区埋地热油管道停输温降影响的研究 总被引:1,自引:0,他引:1
建立冻土区埋地热油管道停输过程水力、热力数学模型,并进行数值计算,考虑了土壤水分迁移、冰水相变及原油凝固潜热、自然对流换热对停输过程管内原油温降的影响,得到了停输期间土壤温度场分布。通过与不考虑水分迁移、冰水相变的停输温降进行对比。研究表明:受水分迁移、冰水相变的影响,管道周围土壤温度等值线向管道两侧移动范围较大,土壤平均温度与不考虑水分时相比偏高,在停输过程中管内原油温降速率小于不考虑水分时的情况,受土壤中水分的影响,停输过程管道周围土壤等温线延Y轴略向下偏移。 相似文献
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埋地热含蜡原油管道的运行中涉及若干复杂的非稳态传热问题。从管内原油传热和管道与外部环境的传热两方面,分析和总结了含蜡原油管道非稳态传热问题的研究现状,介绍了管道在土壤中传热的影响因素,阐述了管道停输状态下管内含蜡原油相变传热的规律及研究方法,建立原油集输系统保温管道散热的数学模型,为评价保温管道状况和界定保温效果衰退程度提供科学的依据。 相似文献
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《化学工程与装备》2020,(4)
某长输管道全长约200km,全线采用加热密闭输送方式,其主要任务是向某炼油厂输送原油。由于该炼油厂装置需定期进行检修(每3-5年/次),为此该长输管道需要停输50天左右,这对该长输管道安全运行提出了更高的要求。在长输管道停输过程中存在原油管道凝管的安全隐患,一方面来自管道的长时间停输后管道内原油温度,另一方面来自管道外部的土壤温度,这两方面问题都会对管道能否再次启运并安全运行造成威胁。因此,研究该长输管道所输送原油的特性、各站场间输送原油的温降情况、炼油厂检修期间长输管道的运行方式,长时间停输后再启动方式等,对于指导管道停输再启动及日常安全运行具有重要意义。 相似文献
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我国原油管道近几十年发展迅速,有些管道已经进入发展中后期,管道发生事故的概率上升。原油管道不可避免发生停输,安全停输时间是再启动的关键参数,对于管道的安全运行至关重要。根据输油管道温降公式,利用迭代法求解公式,并编制了应用软件。研究发现,安全停输时间不是一个定值,它随管道输量、出站温度、自然地温和原油比热容的增加而增加,随总传热系数的增加而降低。当管道周围参数发生变化时,需要密切关注安全停输时间,研究结果可以为原油管道的安全运行提供指导。 相似文献
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以大庆萨北油田高浓度聚合物驱开发区块为研究对象,针对集油管线结蜡严重影响井口回压,为此研究管线淤积物的熔蜡热性。利用差示扫描量热法(DSC)对该区块油田井口到计量间的集油管线的淤积物的熔蜡特性进行分析。分别对水驱管线淤积物和聚驱管线淤积物进行热分析并得到熔蜡过程的热谱图。通过分析比较水驱和聚驱管线淤积物的熔蜡点、熔蜡高峰点、熔蜡热焓等特性参数。根据热谱图得到聚驱管线淤积物的熔蜡点及熔蜡峰温比水驱管线淤积物的熔蜡点及熔蜡峰温高将近40℃,聚驱管线淤积物熔蜡热焓是水驱管线淤积物熔蜡热焓的2~3倍。说明聚驱管线淤积物较水驱管线淤积物更难熔化,所需熔化温度更高、热量更多,也为管线热力清蜡所需的熔蜡点提供理论依据。 相似文献
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Sheng Zheng H. Scott Fogler Amir Haji‐Akbari 《American Institute of Chemical Engineers》2017,63(9):4201-4213
Water‐in‐oil dispersions frequently form in subsea oil pipeline transportation and their presence affects the wax deposition rate in subsea pipelines. A fundamental model for wax deposition on the wall of water‐in‐oil dispersed phase flow pipelines has not been developed. Dispersed water droplets can affect the heat and mass transfer characteristics of wax deposition and alter the deposit growth rate. In this study, wax deposition from water‐in‐oil dispersed flows is comprehensively modeled using first principles of heat and mass transfer. The role of the dispersed water phase on the heat and mass transfer aspects of wax deposition is analyzed. The developed model predicts different effects of the water volume fraction and droplet size on the wax deposition rates in laboratory flow loop experiments and in field scale wax deposition processes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4201–4213, 2017 相似文献
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Contamination of gasoline by wax deposit of diesel is a severe problem in sequential transportation of product oil pipelines in cold areas. However, most works on wax deposition are focused on crude oil. In response, this paper aims to investigate wax deposition from a unique perspective of diesel oil in sequential transportation. To this end, a cold finger apparatus was designed and constructed. It is found that the wax deposition rate of diesel oil increases with oil temperature and wax content, and decreases with cold finger temperature. A non-monotonic variation trend is observed against shear stress. To predict diesel wax deposition rate, a back propagation (BP) neural network optimized by bald eagle search (BES) algorithm is proposed. Grey relational analysis (GRA) is employed to get the highly relevant factors as input parameters of the developed model. Prediction accuracy and generalization ability of the BES-BP model is experimentally verified. This work will be helpful to schedule the transportation program of product oil to avoid contamination of gasoline by diesel wax deposit. 相似文献
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The flow of waxy or paraffinic crude oils in a pipeline could be shutdown for a variety of reasons, resulting in their cooling and subsequent gelling. Gel formation from a multicomponent wax-solvent mixture during flow shutdown was investigated experimentally and analyzed with a transient heat-transfer model based on the moving boundary problem formulation. The gelling experiments were performed with a 0.10 g/g wax-solvent mixture in a flow-loop apparatus, following the formation of a steady-state deposit layer in turbulent flow regime, at two initial wax-solvent mixture temperatures, with a constant coolant temperature, and for different shutdown times. The gel formation was found to be a fast process, which continued until the gel fully occupied the deposition tube. Gas chromatographic analyses of the deposit samples (under sheared cooling) and the gel samples (under static cooling during flow shutdown) indicated significant differences in the composition and the total wax content. The deposit samples showed an enrichment of heavier paraffins, whereas the composition of gel samples was comparable to that of the original wax-solvent mixture. The predictions from the transient model showed that a lower initial oil temperature, a lower coolant temperature, and a smaller pipe diameter would result in a faster blockage of the pipe. The predictions from the moving boundary problem formulation agreed well with the flow shutdown data, which further confirmed that the solid and gel formation from wax-solvent mixtures is modelled satisfactorily as a heat transfer process. 相似文献
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Zhenyu Huang Hyun Su Lee Michael Senra H. Scott Fogler 《American Institute of Chemical Engineers》2011,57(11):2955-2964
Wax deposition in subsea pipelines is a significant economic issue in the petroleum industry. A mathematical model has been developed to predict the increase in both the deposit thickness and the wax fraction of the deposit using a fundamental analysis of the heat and mass transfer for laminar and turbulent flow conditions. It was found that the precipitation of wax in the oil is a competing phenomenon with deposition. Two existing approaches consider either no precipitation (the independent heat and mass transfer model) or instantaneous precipitation (the solubility model) and result in either an overprediction or an underprediction of deposit thickness. By accounting for the kinetics of wax precipitation of wax in the oil (the kinetic model), accurate predictions for wax deposition for both lab‐scale and pilot‐scale flow‐loop experiments with three different oils were achieved. Furthermore, this kinetic model for wax precipitation in the oil was used to compare field‐scale deposition predictions for different oils. © 2011 American Institute of Chemical Engineers AIChE J, 2011 相似文献