Multiperiod Optimization for Production Planning of Petroleum Refineries

Production planning has been the focus of many articles in the mathematical programming literature. In particular, successful operation of oil companies depends on systematic decisions over complex logistics. The present article focuses on the decision-making process involved in petroleum production planning. The proposed model is based on a nonlinear programming formulation that was developed to plan production over a single period. First, the model incorporates multiple planning periods and the selection of different crude oil types. Uncertainty related to petroleum and product prices as well as demand is then included as a set of discrete probabilities. Finally, crude oil handling constraints are added. The resulting models are mixed integer nonlinear programs (MINLP), which were successfully applied to a real-world case at the Petrobras REVAP refinery. Problems of up to 19 time periods and up to five scenarios were solved to optimality.     

Modeling and optimization for oil well production scheduling☆

In this paper, an oil wel production scheduling problem for the light load oil wel during petroleum field exploi-tation was studied. The oil well production scheduling was to determine the turn on/off status and oil flow rates of the wel s in a given oil reservoir, subject to a number of constraints such as minimum up/down time limits and well grouping. The problem was formulated as a mixed integer nonlinear programming model that minimized the total production operating cost and start-up cost. Due to the NP-hardness of the problem, an improved par-ticle swarm optimization (PSO) algorithm with a new velocity updating formula was developed to solve the problem approximately. Computational experiments on randomly generated instances were carried out to eval-uate the performance of the model and the algorithm's effectiveness. Compared with the commercial solver CPLEX, the improved PSO can obtain high-quality schedules within a much shorter running time for all the instances.     

基于PLS的原油选择与混合优化研究

为降低原油采购成本和生产符合质量要求的产品,将原油的选择与混合看作一个整体,基于原油属性数据信息,采用偏最小二乘法建立原油选择与混合优化的非线性混合整数规划模型,应用分支定界算法对模型进行求解,并通过具体实例分析证实了模型和算法的有效性。     

2018 petroleum & chemical industry development report

In 2018, the petroleum and chemical industries of China achieved steady economic growth. The main business income of the entire industry was 12.4 trillion CNY, an increase of 13.6% over the previous year. The total profit was 83.93 billion CNY, an increase of 32.1% over the previous year. The total national oil and gas production reached 334 million tons of oil equivalent, increasing by 2.4% year-on-year. Among the total production, crude oil production was 189 million tons, decreased 1.2%, and natural gas production was 161.02 billion cubic meters, increased 7.5% year on year. Imported crude oil production was 462 million tons, an increase of 10.1% over the last year. Imported gas production was 125.72 billion cubic meters, increased 31.9%. The annual processing capacity of crude oil was 604 million tons, up by 6.8%. The refined oil production was 360 million tons, up by 3.6%. The industry structure was optimized for production growth in 2018, the transformation and upgrading of enterprises and products structure adjustment were sped up, energy efficiency was improved, and overall industrial benefit was rebounded. At present, the economic operation of the industry is still not very stable, and downward pressure is still great, mainly being reflected in the overcapacity of some industries, high cost operation of enterprises, increased tax burden, and weak investment. With the slow recovery of the global economy and the key support of high-quality development through technological innovation, it is expected that the petroleum and chemical industry of China will achieve the general objective of steady growth in 2019.     

结合质量传递及约束的炼油生产计划优化

To address the issues of heavier crude oil and stringent product quality regulation,this paper presents a refinery planning model that integrates physical properties tracking and quality constraints.The proposed model selected crude oil’s key property of true boiling point curve as classification criteria and applied a K-means clustering to it,introduced swing cut to achieve a higher yield of valuable fractions,tracked and restricted petroleum products’ sulfur content as well as other key properties,and later proposed a universal solving strategy to deal with highly nonlinear quality constraints.The model was illustrated by representative case studies,the results showed that refinery planning optimization combined with quality tracking and constraints could satisfy product quality requirement while achieving a maximum refinery profit.     

Optimal operation of cryogenic air separation systems with demand uncertainty and contractual obligations

Cryogenic air separation is an efficient technology for supplying large quantities of nitrogen, argon, and oxygen to chemical, petroleum and manufacturing customers. However, numerous uncertainties make effective operation of these complex processes difficult. This work addresses the problem of determining an optimal operating strategy to maximize the total profit of a cryogenic air separation process while considering demand uncertainty and contractual obligations. A rigorous process model is included as constraints in a nonlinear programming formulation. Uncertain demands are assumed to be normally distributed with known mean and standard deviation, and expected profit in the objective function is evaluated using the standard loss function. A probabilistic fill-rate expression, also based on the loss function, is used to model the contractual obligations by providing a lower bound on the expected product sales. In the single period case with one customer satisfaction constraint, the nonlinear programming formulation can be solved efficiently using the general purpose nonlinear optimization package, Ipopt. This formulation is then extended to include multiple time periods, the potential for product storage, and customer satisfaction constraints on multiple products. To solve the large-scale nonlinear programming formulation that considers a seven-day operating horizon, a tailored parallel nonlinear programming algorithm is used. This approach makes use of a Schur complement decomposition strategy to exploit the block structure of the problem and allow efficient solution in parallel. Using these tools, we solve for a set of optimal operating strategies over the complete space of different fill rates. This produces planning figures that identify key trade-offs between profitability and contractual obligations.     

Procurement planning in oil refining industries considering blending operations

This paper addresses procurement planning in oil refining, which has until now only had limited attention in the literature. We introduce a mixed integer nonlinear programming (MINLP) model and develop a novel two-stage solution approach, which aims at computational efficiency while addressing the problems due to discrepancies between a non-linear and a linearized formulation. The proposed model covers realistic settings by allowing the blending of crude oil in storage tanks, by modeling storage tanks and relevant processing units individually, and by handling more crude oil types and quality parameters than in previous literature. The developed approach is tested using historical data from Statoil A/S as well as through a comprehensive numerical analysis. The approach generates a feasible procurement plan within acceptable computation time, is able to quickly adjust an existing plan to take advantage of individual procurement opportunities, and can be used within a rolling time horizon scheme.     

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.     

Source-based discrete and continuous-time formulations for the crude oil pooling problem

The optimization of crude oil operations in refineries is a challenging scheduling problem due to the need to model tanks of varying composition with nonconvex bilinear terms, and complicating logistic constraints. Following recent work for multiperiod pooling problems of refined petroleum products, a source-based mixed-integer nonlinear programming formulation is proposed for discrete and continuous representations of time. Logistic constraints are modeled through Generalized Disjunctive Programming while a specialized algorithm featuring relaxations from multiparametric disaggregation handles the bilinear terms. Results over a set of test problems from the literature show that the discrete-time approach finds better solutions when minimizing cost (avoids source of bilinear terms). In contrast, solution quality is slightly better for the continuous-time formulation when maximizing gross margin. The results also show that the specialized global optimization algorithm can lead to lower optimality gaps for fixed CPU, but overall, the performance of commercial solvers BARON and GloMIQO are better.     

Global optimization for scheduling refinery crude oil operations

In this work we present an outer-approximation algorithm to obtain the global optimum of a nonconvex mixed-integer nonlinear programming (MINLP) model that is used to represent the scheduling of crude oil movement at the front-end of a petroleum refinery. The model relies on a continuous time representation making use of transfer events. The proposed algorithm focuses on effectively solving a mixed-integer linear programming (MILP) relaxation of the nonconvex MINLP to obtain a rigorous lower bound (LB) on the global optimum. Cutting planes derived by spatially decomposing the network are added to the MILP relaxation of the original nonconvex MINLP in order to reduce the solution time for the MILP relaxation. The solution of this relaxation is used as a heuristic to obtain a feasible solution to the MINLP which serves as an upper bound (UB). The lower and upper bounds are made to converge to within a specified tolerance in the proposed outer-approximation algorithm. On applying the proposed technique to test examples, significant savings are realized in the computational effort required to obtain provably global optimal solutions.     

炼化一体智能化工厂计划优化模型设计及应用实践

炼化企业供应链协同优化对实现智能炼厂至关重要,计划优化系统是供应链协同优化实现的核心系统。本文详细介绍了规划总院自主研发的新一代计划优化软件整体框架及主要功能,在该平台基础上结合炼化一体化企业流程数据、原油数据库及产品销售等边界条件进行了炼化一体化模型设计及建设,用于开展各类优化分析,并基于线性规划原理,通过边际效益分析及多方案对比分析,结合原油保本价法、缩减成本法及等量替代法等不同的原油选购方法,开展了原油选购测算及应用分析,并对炼化一体化企业加工原油提出了相关建议,指导企业原油选购。     

A game theoretic framework for petroleum refinery strategic production planning

A game theoretic framework for strategic refinery production planning is presented in which strategic planning problems are formulated as non‐cooperative potential games whose solutions represent Nash equilibria. The potential game model takes the form of a nonconvex nonlinear program (NLP) and we examine an additional scenario extending this to a nonconvex mixed integer nonlinear program (MINLP). Tactical planning decisions are linked to strategic decision processes through a potential game structure derived from a Cournot oligopoly‐type game in which multiple crude oil refineries supply several markets. Two scenarios are presented which illustrate the utility of the game theoretic framework in the analysis of production planning problems in competitive scenarios. Solutions to these problems are interpreted as mutual best responses yielding maximum profit in the competitive planning game. The resulting production planning decisions are rational in a game theoretic sense and are robust to deviations in competitor strategies. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2751–2763, 2017     

基于特征选择的常减压装置模型及在计划优化中的应用

常减压装置将原油切割为不同中间产品,其作为炼油工艺的龙头装置,对炼油过程生产计划排产与效益提升至关重要。通过建立一种高精度且具有良好求解效率的常减压模型,用以求解模型关键指标实沸点（TBP）曲线,即综合考虑切割产品的实沸点（TBP）与原油TBP、流量、温度等变量影响,构建非线性方程组模型来表征输入输出间的关系;利用特征选择方法遴选相关变量（包括进料性质、相邻TBP及其二次项等）,并采用鲸鱼优化算法优化方程组系数。仿真结果表明,该多输出相互关系模型与已有文献工作相比,在兼顾求解效率基础上,常减压装置各蒸馏切割产品TBP曲线预测上有更高的精度,将此模型应用到炼厂计划优化中,与传统的悬摆切割模型对比,优化结果优于传统悬摆切割模型。     

Process and Catalyst Needs for Hydrodenitrogenation

During the last decade there has been increased interest in the production of synthetic fuels and chemicals feedstocks from coal and oil shale due to declining petroleum reserves. Table 1 gives the projected gasoline to mid-distillate ratio through the year 2000 and beyond; the shift is away from high-octane fuels requiring a relatively high aromatics content and a relatively low hydrogen content to highly paraffin-based fuels having a high hydrogen content. Figure 1 shows the projected United States energy supply and demand through the year 1990 [2], Current petroleum production in the contiguous United States is about 9 million bbl/day and has declined at a rate of about 0.5 million bbl/day per year for a number of years. Alaskan oil will arrest this decline in production briefly but will not make up for even the loss in the rate of petroleum production incurred in the contiguous 48 states during the last 5 years. In all probability, declining production from current oil fields will not be offset by further new discoveries, and thus the United States will become increasingly dependent on foreign oil. Further, petroleum feedstocks are becoming harder to process as crude quality decreases, and as it becomes more and more necessary to process the bottom of the barrel. Declining oil supply in the face of increasing demand will ultimately require that some of the projected gap be made up with synthetics made from coal and oil shale. Such synthetic feedstocks and heavier petroleum fractions contain higher concentrations of nitrogen than light petroleum stocks, are decidedly more difficult to process, and will place increasing demands on hydroprocessing catalysts and processes.     

Process and Catalyst Needs for Hydrodenitrogenation

During the last decade there has been increased interest in the production of synthetic fuels and chemicals feedstocks from coal and oil shale due to declining petroleum reserves. Table 1 gives the projected gasoline to mid-distillate ratio through the year 2000 and beyond; the shift is away from high-octane fuels requiring a relatively high aromatics content and a relatively low hydrogen content to highly paraffin-based fuels having a high hydrogen content. Figure 1 shows the projected United States energy supply and demand through the year 1990 [2], Current petroleum production in the contiguous United States is about 9 million bbl/day and has declined at a rate of about 0.5 million bbl/day per year for a number of years. Alaskan oil will arrest this decline in production briefly but will not make up for even the loss in the rate of petroleum production incurred in the contiguous 48 states during the last 5 years. In all probability, declining production from current oil fields will not be offset by further new discoveries, and thus the United States will become increasingly dependent on foreign oil. Further, petroleum feedstocks are becoming harder to process as crude quality decreases, and as it becomes more and more necessary to process the bottom of the barrel. Declining oil supply in the face of increasing demand will ultimately require that some of the projected gap be made up with synthetics made from coal and oil shale. Such synthetic feedstocks and heavier petroleum fractions contain higher concentrations of nitrogen than light petroleum stocks, are decidedly more difficult to process, and will place increasing demands on hydroprocessing catalysts and processes.     

三氧化硫制备石油磺酸盐工艺及组成分析方法综述

在我国石油工业,一次、二次采油对原油的采取率仅约40％。由于石油是不可再生资源,所以为了不造成浪费就不得不进行三次采油,而石油磺酸盐则是三次采油过程中常用的驱油剂,其制备工艺因选择的磺化剂不同而不同,作者则主要对以三氧化硫磺化制备石油磺酸盐的工艺和现在常用石油磺酸盐组成分析方法进行了综述与简要分析。     

Conductivity analysis for free fatty acids in oil from glandless cottonseed

Attempts to determine free fatty acids in petroleum ether extracts of cottonseed and crude cottonseed oil by conductivity measurements were unsuccessful due to interference of gossypol. With new strains of glandless cottonseed, which do not contain gossypol, analysis of free fatty acids by conductivity was successful on both the petroleum ether extracts and on the crude oil. An important advantage of conductivity over titration is that sample preparation is eliminated, since conductivity measurements are made on the oil extracts from the total oil determination.     

Constrained thermohydraulic optimization of the flow rate distribution in crude preheat trains

Crude preheat trains are heat exchanger networks which heat the crude oil stream in the petroleum distillation using hot product streams and pumparounds. The final heating step is executed in a furnace. The thermal efficiency of this process is strongly dependent on the crude preheat train performance, and, during the refinery operation, the heat load of the exchangers may decrease due to fouling. Associated to the reduction of the thermal effectiveness of the heat exchangers, fouling also causes an increase of the flow resistances along the thermal equipment. A potential approach to mitigate this problem is based on the optimization of the distribution of the flow rates in the crude preheat train for maximizing the final crude temperature. In this context, this paper presents a constrained nonlinear programming formulation for this task. The equality constraints encompass mass, energy and mechanical energy balances and heat exchanger equations for describing the thermal and hydraulic behavior of the system. The performance of the proposed approach is explored using two examples, a simple network and a crude preheat train based on a real Brazilian refinery.     

原油作业过程优化的研究进展

原油作业过程是石油供应链的重要组成环节,包括炼油企业生产过程中的原油采购、原油分配、原油输送、原油储存和原油调和等多个工业流程。原油作业过程优化具有很高的学术理论价值与工业应用价值,与其相关的研究工作是目前学术界与工业界共同关注的热点。首先简要描述了原油作业过程,并对其优化问题的难点进行分析;其次,分别从优化模型、优化算法以及不确定性优化方法三个研究角度,重点阐述了原油采购优化、原油储运优化、原油调和优化以及不确定性条件下原油作业优化四个主要研究方向的学术进展,并对当前已有的研究成果进行了归纳总结;最后,对原油作业过程优化当前存在的一些问题提出了建议,并对该领域未来的发展方向与趋势进行了展望。     

炼油企业生产运营系统的活动模型研究

本文针对炼油企业各个环节的特点,建立了炼油企业生产运营系统活动模型。将需求预测、生产计划和原油采购等部分进行活动模型分解。建立了炼油企业生产运营系统IDEFO模型。