共查询到19条相似文献,搜索用时 156 毫秒
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为保障海上终端装卸船海底热油管道安全经济运行,引入了国外始于深海油气田开发的流动保障的概念,建立了海底热油管道的水力、热力模型.为了提高计算的准确性,在建立热力模型时,采用变化的比热容进行计算,考虑了含蜡原油结晶潜热的影响;建立水力模型时,考虑了含蜡原油在管内流动的温降过程是蜡结晶的相变过程,采用了分段计算方法.同时,... 相似文献
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苏丹某油田是稠油为主力区块的油田,油品密度大、含蜡高、倾点高。站内脱水工艺为两级分离,两级换热的三相分离器热化学分离。投产后由于产量增加,原油含水率上升,运行参数发生了变化。文中通过对站内工艺流程和原油物性的分析,提出了调整流程的建议。 相似文献
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针对长吉输油管线采用混合输送方式输送俄罗斯原油和大庆原油及该管线的工程实际,以总运行费用最小为原则,以各站进站温度和开泵方案为决策变量,建立了该管线优化运行的数学模型,采用穷举法穷举出各种可能的开泵方案作为外层嵌套,将进站温度的优化作为内层嵌套求解该模型。通过某天实际运行方案和优化运行方案对比可以看出,优化运行方案总费用降低7%。 相似文献
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原油结蜡是影响管道安全、经济和高效运行的一个重要因素。为了对输油管道的结蜡状况进行预测,掌握输油管道结蜡的基本规律,应用灰色系统理论中的模型对输油管道结蜡速度和结蜡厚度等指标的实际统计数据进行了灰色动态拟合,建立了相应的灰色微分方程和时间响应函数。结果表明:残差小于2%,模型精度满足工程实际需要。 相似文献
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Maritime transportation, the primary mode for intercontinental movement of crude oil, accounts for 1.7 billion tons annually – bulk of which are carried via a fleet of large crude oil tankers. Although spectacular episodes such as Exxon Valdez underline the significant risk and tremendous cost associated with marine shipments of hazardous materials, maritime literature has focused only on the cost-effective scheduling of these tankers. It is important that oil transport companies consider risk, since the insurance premiums is contingent on the expected claim. Hence through this work, we present a mixed-integer optimization program – with operating cost and transport risk objectives, which could be used to prepare routes and schedules for a heterogeneous fleet of crude oil tankers. The bi-objective model was tested on a number of problem instances of realistic size, which were further analyzed to conclude that the cheapest route may not necessarily yield the lowest insurance premiums, and that larger vessels should be used if risk is more important as it enables better exploitation of the risk structure. 相似文献
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基于有限容积法,建立伴热稠油管道停输过程的非稳态传热模型,采用"焓-多孔度"技术,利用FLUENT软件,分别对伴热管与稠油管同时停输及稠油管道单独停输两种情况进行了数值模拟,并考虑了析蜡潜热对温降的影响,得出了不同时刻管内原油凝固区、混合区、液油区的位置及温度场的分布。结果表明:两种情况下,稠油固化过程基本相同。稠油管道单独停输时,管内原油温降速率比双管同停温降速率略慢,但在一定时间内相差不大。随着停输时间的延长,两种情况下管内稠油温降速率变化明显,说明伴热管对稠油管道短期停输影响不大。文中给出安全停输时间,为工程设计提供一定指导。 相似文献
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Numerous studies have established the link between the built environment and travel behavior. However, fewer studies have focused on environmental costs of travel (such as CO2 emissions) with respect to residential self-selection. Combined with the application of TIQS (Travel Intelligent Query System), this study develops a structural equations model (SEM) to examine the effects of the built environment and residential self-selection on commuting trips and their related CO2 emissions using data from 2015 in Guangzhou, China. The results demonstrate that the effect of residential self-selection also exists in Chinese cities, influencing residents’ choice of living environments and ultimately affecting their commute trip CO2 emissions. After controlling for the effect of residential self-selection, built environment variables still have significant effects on CO2 emissions from commuting although some are indirect effects that work through mediating variables (car ownership and commuting trip distance). Specifically, CO2 emissions are negatively affected by land-use mix, residential density, metro station density and road network density. Conversely, bus stop density, distance to city centers and parking availability near the workplace have positive effects on CO2 emissions. To promote low carbon travel, intervention on the built environment would be effective and necessary. 相似文献
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We propose a macroscopic model of lane‐changing that is consistent with car‐following behavior on a two‐lane highway. Using linear stability theory, we find that lane‐changing affects the stable region and the propagation speeds of the first‐order and second‐order waves. In analyzing a small disturbance, our model effectively reproduces certain non‐equilibrium traffic‐flow phenomena—small disturbance instability, stop‐and‐go waves, and local clusters that are affected by lane‐changing. The model also gives the flow‐density relationships in terms of the actual flow rate, the lane‐changing rate, and the difference between the potential flow rate (the flow rate that would have occurred without lane‐changing) and the actual flow rate. The relationships between the actual flow rate and traffic density and between the lane‐changing rate and traffic density follow a reverse‐lambda shape, which is largely consistent with observed traffic phenomena. 相似文献