大型原油储罐防静电流速研究

大型原油储罐往往采用大型油轮进库的方式装卸原油,在满足装卸船时间的要求也必须满足防静电流速的要求.静电的产生与所装卸油品的性质、装卸油管道的长度、管径和流量等因素有关.因此,有必要对它们之间的关系进行研究以保证输油的安全.通过建立以场强和装卸船时间为约束条件的数学模型,在给定初始管径求解满足装卸时间要求的流速,判断是否满足防静电要求,满足则流速可继续增加,直到不满足时输出流速;不满足则按50 mm一档加大管径重新进行循环计算,并给出具体算例进行求解,得出满足100000 m3油罐卸100000 t油轮最小管径为DN400. 同时对理论计算与经验公式进行比较,得出经验公式更适合成品油防静电流速的计算,并不适合原油防静电流速的计算.理论计算误差较小,仅为2.8%.建立的数学模型为原油管道的设计和运行提供理论支持.     

A study on scheduling of naphtha transportation and storage systems for naphtha cracking center

The rapid increase of petroleum prices compelled to petro-chemical industries to figure out ways to remove any potential redundancies in and out of their network. The increasing attention on integrating activities that have been addressed separately is in line with this trend. Particularly this paper addresses a naphtha feeding problem for Naphtha Cracking Center (NCC). The naphtha feeding problem involves two key operations: delivering naphtha from refineries to NCC and blending naphtha in storage tanks before feeding it to NCC. While the first is concerned with selecting sources and scheduling the loading and unloading of naphtha, the latter involves the transfer of the naphtha from storage tanks to a charging tank. This paper considers both issues simultaneously by transforming them into a single mixed linear integer programming problem of minimizing the cost function of naphtha prices, shipping expenses, and unloading costs, etc. A numerical example of a real industrial case is presented to illustrate the applicability of the proposed model.     

A multi-level simulation approach for the crude oil loading/unloading scheduling problem

An integrated approach for refinery production scheduling and unit operation optimization problems is presented. Each problem is at a different decision making layer and has an independent objective function and model. The objective function at the operational level is an on-line maximization of the difference between the product revenue and the energy and environmental costs of the main refinery units. It is modeled as an NLP and is constrained by ranges on the unit's operating condition as well as product quality constraints. The production scheduling layer is modeled as an MILP with the objective of minimizing the logistical costs of unloading the crude oil over a day-to-week time horizon. The objective function is a linear sum of the unloading, sea waiting, inventory, and setup costs. The nonlinear simulation model for the process units is used to find optimized refining costs and revenue for a blend of two crudes. Multiple linear regression of the individual crude oil flow rates within the crude oil percentage range allowed by the facility is then used to derive linear refining cost and revenue functions. Along with logistics costs, the refining costs or revenue are considered in the MILP scheduling objective function. Results show that this integrated approach can lead to a decrease of production and logistics costs or increased profit, provide a more intelligent crude schedule, and identify production level scheduling decisions which have a tradeoff benefit with the operational mode of the refinery.     

Development of refinery scheduling system using mixed integer programming and expert system

This paper presents a hybrid refinery scheduling system combining mathematical programming model and expert system. Mixed-integer linear programming models for crude oil movement between units are merged into the expert system that is for qualitative issues concerning crude vessel unloading operations. The target problem ranging from the crude unloading to the crude charging to distillation towers is decomposed into several module problems for efficiency. Compared with existing scheduling approaches for oil movement, the proposed hybrid refinery scheduling system is very effective in dealing with timing decisions involving vessel unloading operations due to the advantages of an expert system. Since the proposed scheduling system can generate solutions so fast, it is expected to play a key role in the real processes. This paper is dedicated to Professor Wha Young Lee on the occasion of his retirement from Seoul National University.     

Continuous‐time modeling and global optimization approach for scheduling of crude oil operations

Scheduling of crude oil operations is a critical and complicated component of overall refinery operations, because crude oil costs account for about 80% of the refinery turnover. Moreover, blending with less expensive crudes can significantly increase profit margins. The mathematical modeling of blending different crudes in storage tanks results in many bilinear terms, which transforms the problem into a challenging, nonconvex, and mixed‐integer nonlinear programming (MINLP) optimization model. Two primary contributions have been made. First, the authors developed a novel unit‐specific event‐based continuous‐time MINLP formulation for this problem. Then they incorporated realistic operational features such as single buoy mooring (SBM), multiple jetties, multiparcel vessels, single‐parcel vessels, crude blending, brine settling, crude segregation, and multiple tanks feeding one crude distillation unit at one time and vice versa. In addition, 15 important volume‐based or weight‐based crude property indices are also considered. Second, they exploited recent advances in piecewise‐linear underestimation of bilinear terms within a branch‐and‐bound algorithm to globally optimize the MINLP problem. It is shown that the continuous‐time model results in substantially fewer bilinear terms. Several examples taken from the work of Li et al. are used to illustrate that (1) better solutions are obtained and (2) ε‐global optimality can be attained using the proposed branch‐and‐bound global optimization algorithm with piecewise‐linear underestimations of the bilinear terms. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

A new continuous-time formulation for scheduling crude oil operations

In today's competitive business climate characterized by uncertain oil markets, responding effectively and speedily to market forces, while maintaining reliable operations, is crucial to a refinery's bottom line. Optimal crude oil scheduling enables cost reduction by using cheaper crudes intelligently, minimizing crude changeovers, and avoiding ship demurrage. So far, only discrete-time formulations have stood up to the challenge of this important, nonlinear problem. A continuous-time formulation would portend numerous advantages, however, existing work in this area has just begun to scratch the surface. In this paper, we present the first complete continuous-time mixed integer linear programming (MILP) formulation for the short-term scheduling of operations in a refinery that receives crude from very large crude carriers via a high-volume single buoy mooring pipeline. This novel formulation accounts for real-world operational practices. We use an iterative algorithm to eliminate the crude composition discrepancy that has proven to be the Achilles heel for existing formulations. While it does not guarantee global optimality, the algorithm needs only MILP solutions and obtains excellent maximum-profit schedules for industrial problems with up to 7 days of scheduling horizon. We also report the first comparison of discrete- vs. continuous-time formulations for this complex problem.     

Phase change composites with thermal-formability and photothermal storage property for high flux crude oil transmission

Crude oil pipeline transportation is one of widely used ways in land transportation and comprises a large share of the world's long-distance oil transmission. Warming and heat preservation of crude oil is vital for efficient oil pipeline transportation. However, it remains a formidable challenge in coping with caused tremendous energy consumption and environmental pollution. In this work, bio-based phase change composites with superior thermal-formability and photothermal storage properties were fabricated and molded to photothermal oil transportation system using template-confined thermoforming strategy. On the basis of desirable thermal energy management ability of PEG as well as the synergistic effects between heat localization and electron nonradiative transition of Fe₂O₃ nanoparticles, the system realized a remarkable decrease in oil viscosity and efficient transmission. Particularly, the preparation process could be facilely scaled up and indicate real application feasibility. This successful exploration offers a significant path for developing green, highly effective crude oil transportation.     

Optimization of crude distillation system using aspen plus: Effect of binary feed selection on grass-root design

With an objective to supplement guidelines available as general rules of thumb for the grass-root design of crude distillation unit (CDU) using binary crude mixtures, this work presents the optimization of crude distillation unit using commercial Aspen Plus software. The crude distillation unit constituted a pre-flash tower (PF), an atmospheric distillation unit (ADU) and a vacuum distillation unit (VDU). Optimization model constituted a rigorous simulation model supplemented with suitable objective functions with and without product flow rate constraints. Three different feed stocks namely Bombay crude, Araby crude and Nigeria crude were considered in this work along with various binary combinations of these crudes. The objective function considered was profit function (subjected to maximization) for cases without product flow rate constraints and raw-materials and energy cost (subjected to minimization) for cases with product flow rate constraints. Parametric study pertaining to feed selection and composition has been conducted in this work to further benefit refinery planning and scheduling. Simulation study inferred that the product flow rate constraints sensitively affect atmospheric distillation column diameter and crude feed flow rate calculations. Based on all simulation studies, a generalized inference confirms that it is difficult to judge upon the quality of the solutions obtained as far as their global optimality is concerned.     

串联泵输油工艺在华锦集团输油管道上的应用

结合中国兵器华锦集团储运工程项目,对原油长输管道中泵站的串联泵和并联泵输油工艺进行了综合比较,优化出串联泵输油工艺方案,并对串联输油泵系统的压力调节、安全保护系统等工艺技术进行简要介绍.     

New approach for scheduling crude oil operations

Scheduling of crude oil operations is crucial to petroleum refining, which includes determining the times and sequences of crude oil unloading, blending, and CDU feeding. In the last decades, many approaches have been proposed for solving this problem, but they either suffered from composition discrepancy [Lee et al. 1996. Mixed-integer linear programming model for refinery short-term scheduling of crude oil unloading with inventory management. Industrial and Engineering Chemistry Research 35, 1630-1641; Jia et al., 2003. Refinery short-term scheduling using continuous time formulation: crude-oil operations. Industrial and Engineering Chemistry Research 42, 3085-3097; Jia and Ierapetritou, 2004. Efficient short-term scheduling of refinery operations based on a continuous time formulation. Computer and Chemical Engineering 28, 1001-1019] or led to infeasible solutions for some cases [Reddy et al., 2004a. Novel solution approach for optimizing crude oil operations. A.I.Ch.E. Journal 50(6), 1177-1197; 2004b. A new continuous-time formulation for scheduling crude oil operations. Chemical Engineering Science 59, 1325-1341]. In this paper, coastal and marine-access refineries with simplified workflow are considered. Unlike existing approaches, the new approach can avoid composition discrepancy without using iterative algorithm and find better solution effectively. In this approach, a new mixed integer non-linear programming (MINLP) formulation is set up for crude oil scheduling firstly, and then some heuristic rules collected from expert experience are proposed to linearize bilinear terms and prefix some binary variables in the MINLP model. Thus, crude oil scheduling can be expressed as a complete mixed integer linear programming (MILP) model with fewer binary variables. To illustrate the advantage of the new approach, four typical examples are solved with three models. The new model is compared with the most effective models (RKS(a) and RKS(b) models) presented by Reddy et al. [2004a. Novel solution approach for optimizing crude oil operations. A.I.Ch.E. Journal 50(6), 1177-1197; 2004b. A new continuous-time formulation for scheduling crude oil operations. Chemical Engineering Science 59, 1325-1341], which proves that the new approach is valid and feasible in most small-size and medium-size problems.     

考虑碳排放量的穿梭油轮路径绿色调度优化

海上穿梭油轮在深远海及海上边际油田的石油外输系统中担任着重要角色,其路径规划决定着整个石油外输系统运输效率.海上原油运输方式占整个原油运量的80％,为提高原油公司市场竞争力、降低其海运成本,对穿梭油轮船队的合理设计及路径的调度优化至关重要.近年来,学者更注重于研究建立一种与环境共生的、能促进经济和消费生活健康发展的绿色...     

Decision support for integrated refinery supply chains: Part 1. Dynamic simulation

Supply chain studies are increasingly given top priority in enterprise-wide management. Present-day supply chains involve numerous, heterogeneous, geographically distributed entities with varying dynamics, uncertainties, and complexity. The performance of a supply chain relies on the quality of a multitude of design and operational decisions made by the various entities. In this two-part paper, we demonstrate that a dynamic model of an integrated supply chain can serve as a valuable quantitative tool that aids in such decision-making. In this Part 1, we present a dynamic model of an integrated refinery supply chain. The model explicitly considers the various supply chain activities such as crude oil supply and transportation, along with intra-refinery supply chain activities such as procurement planning, scheduling, and operations management. Discrete supply chain activities are integrated along with continuous production through bridging procurement, production, and demand management activities. Stochastic variations in transportation, yields, prices, and operational problems are considered in the proposed model. The economics of the refinery supply chain includes consideration of different crude slates, product prices, operation costs, transportation, etc. The proposed model has been implemented as a dynamic simulator, called Integrated Refinery In-Silico (IRIS). IRIS allows the user the flexibility to modify not only parameters, but also replace different policies and decision-making algorithms in a plug-and-play manner. It thus allows the user to simulate and analyze different policies, configurations, uncertainties, etc., through an easy-to-use graphical interface. The capabilities of IRIS for strategic and tactical decision support are illustrated using several case studies.     

A generalized model for predicting non-Newtonian viscosity of waxy crudes as a function of temperature and precipitated wax

Precipitated wax, shear and thermal history have pronounced effects on viscosity and rheological behavior of waxy crudes. On the basis of mechanism of waxy crude rheology, a shear-rate-dependent viscosity model has been developed by applying theory of suspension rheology. This model is characterized by its capability to predict viscosities of crude oils with various thermal and shear history and beneficiated with pour-point-depressants (PPD). Once viscosities at only two temperatures above the wax appearance temperature and apparent viscosities at one temperature in the non-Newtonian regime are known, viscosities or apparent viscosities at any temperatures above the gel point can be predicted by using the model together with the concentration of precipitated wax at that specified temperature. Verification by using 3458 viscosity data points ranging from 5 to 2900 mPa s from 33 virgin crudes and 14 PPD-beneficiated crudes with various thermal and shear history shows that the model predicts viscosities with an absolute average deviation of 7.43%. Furthermore parameters of rheological models such as the consistency coefficient K and the flow behavior index n of the power law model may be obtained by regressing predicted viscosity data and corresponding shear-rates.     

高分子生物表面活性剂Emulsan的研究进展

详细介绍了高分子生物表面活性剂Emulsan的生物合成、物化性质以及在稠油管道运输和油罐清洗中的应用。Emulsan是醋酸钙不动杆菌RAG-1代谢产生的胞外脂多糖,它不能显著降低油-水的界面张力,而是分布在油滴的表面,有效地阻止它们的聚并,使O/W型乳状液稳定,从而有助于它在石油工业中的应用。并对Emulsan研究方向及应用发展趋势进行了展望。     

输油管线节能运行研究

原油输送过程中能耗主要体现为输油泵用电和加热装置用气,输油管线的节能运行在于如何用最少的动能消耗和热能消耗完成原油的输送任务。对于管径大、输量大的某输油管线,如何降低输油能耗,成为研究的重点。通过对某输油管线进行工况分析和现场试验,找出了一种最经济的运行方式,并为输油管线节能运行提供了理论依据。     

基于风险的油田油气集输管线维护决策优化方法

将长输管道最优完整性维护决策方法——损失函数法应用于油气集输管线的维护决策优化.该方法以油田油气集输管线的风险检测和风险评价结果为基础,通过引入决策准则、后果函数、状态集及决策集等概念,并对油气集输管线失效后果量化,进而建立决策优化数学模型.通过计算各决策的损失函数确定最优的维护决策方案,应用此方法对某原油外输管线进行了维护决策优化,达到了较好的维护效果.     

不确定性在管道流动安全评价中的研究进展

油气集输管网的设计首先要保证管道内介质流动的安全性,由于与原油管道输送相关的原油物性参数、运行参数、环境因素具有很强的不确定性,因此传统的确定性方法进行管道流动安全性评价有很多局限性。回顾了国内学者对管道输送相关参数不确定性研究现状,并对油气储运工程领域不确定性研究的发展趋势进行了探讨,从而为管道流动安全性评价提供了理论基础。     

油品粘度对输油管道弯管结构的影响规律分析

对于长距离输送管道而言,为了提高管道的输送效率,降低输送成本,如何有效地降低沿程损失便成为首要解决的问题。具有较高粘度的油品会大大增加输送过程中的沿程摩阻损失,为了更好地分析油品粘度对管道的影响,通过建立输油管道弯管结构的有限元力学模型,针对油品流经管道弯管时,油品粘度对管道温度场与应力场的影响规律进行分析。研究结果表明,油品粘度在增加管道沿程损失与局部摩阻损失的同时,也给弯管处温度场与应力场造成极大的影响,并且对管道温度场与应力场的作用规律不尽相同,这对输油管道弯管结构的安全性产生较大的危害。通过研究分析了油品粘度对管道的影响规律,为油品的降粘输送提供了理论指导依据。     

稠油管道输送技术研究

高粘的稠油使得输送成为管道从业者的一个难题,尤其是发生凝管事故后的再启动问题。对稠油高粘的实质进行研究发现,决定稠油粘度的实质为原油体系中沥青质分子和非沥青质分子相互作用所形成的大分子胶束聚集体所致。国内外稠油输送方法有加热法、裂解降粘法、掺稀输送法、添加改性剂法、低粘液环输送法、微生物法、超声波法和超临界CO2输送法。各方法各具优缺点,没有一种方法适用于所有稠油,另外还需要考虑经济性问题。目前国内最常用的输送方法为加热法和掺稀法。在实际中,针对不同稠油要进行一定的技术分析和研究才能决定选择何种输送技术。     

输油管道顺序输送的热力模拟研究

同一管道输送流变特性差异很大的多种原油,不同凝固点不同出站温度的原油顺序输送,必然导致土壤温度场的波动,这是一个不稳态传热问题,因此建立了顺序输送不稳态温度场及土壤温度场模型进行分析.利用有限差分法,使用混合网格,即在差分网格的划分中使用了混合网格法,在土壤内部的大部分区域使用矩形网格划分,在管壁附近使用极网格;把模型的热传导偏微分方程转化为线性方程组,用迭代法求解.以湛江至茂名输油管道为例,对其顺序输送不同国家原油的热力状况进行了模拟计算.通过对混输中各阶段油头温度和土壤温度场的分析可知,该模型可确定顺序输送次序和油品出站温度等参数,为制定管输方案提供理论依据.