Dynamic hybrid simulation of batch processes driven by a scheduling module

Simulation is now a CAPE tool widely used by practicing engineers for process design and control. In particular, it allows various offline analyses to improve system performance such as productivity, energy efficiency, waste reduction, etc. In this framework, we have developed the dynamic hybrid simulation environment PrODHyS whose particularity is to provide general and reusable object-oriented components dedicated to the modeling of devices and operations found in chemical processes. Unlike continuous processes, the dynamic simulation of batch processes requires the execution of control recipes to achieve a set of production orders. For these reasons, PrODHyS is coupled to a scheduling module (ProSched) based on a MILP mathematical model in order to initialize various operational parameters and to ensure a proper completion of the simulation. This paper focuses on the procedure used to generate the simulation model corresponding to the realization of a scenario described through a particular scheduling.     

OPTIMIZATION OF A WOOD DRYER KILN USING THE MIXED INTEGER PROGRAMMING TECHNIQUE: A CASE STUDY

Abstract

When wood is to be utilized as a raw material for furniture, buildings etc., it must be dried from approximately 100% to 6% moisture content. This is achieved at least partly in a drying kiln. Heat for this purpose is provided by electrical means, or by steam from boilers fired with wood chips or oil. By making a close examination of monitored values from an actual drying kiln it has been possible to optimize the use of steam and electricity using the so called mixed integer programming technique Owing to the operating schedule for the drying kiln it has been necessary to divide the drying process in very short lime intervals i.e., a number of minutes. Since a drying cycle takes about two or three weeks, a considerable mathematical problem is presented and this has to be solved.     

Optimization of the heat plant of district energy systems

This paper presents a scheme to achieve structural and operational optimization for the heat plant in a district energy system. A district energy system consists of energy suppliers and consumers, district heating pipelines and heat storage facilities in a region. Production and consumption of energy and transport of energy as well as storage of heat are taken into account in the model. The problem is formulated as a mixed integer linear programming (MILP) problem where the objective is to minimize the overall cost of the district energy system. Evaluation of the energy production cost is based on the daily operation for every season at the plant located at Suseo in Seoul, Korea. From the results of numerical simulations we can see that the district energy system is well approximated by the proposed model, and that the energy efficiency is improved by the application of the optimal operation conditions provided by the proposed model.     

Development Tendency of the Refractories for Iron ＆ Steel Industry in China

This paper introduces the developing tendency of refractories for iron and steel industry combined with the new metallurgical techniques applied in iron and steel industry in China. Refractories for blast furnace long service life, smelting reduction iron-making process, secondary refining metallurgies and clean steel making, near net shape continuous casting are described respectively. To meet the requirement of iron and steel industry, the high quality, multi-functions and environment-friendly refractories with long service llfe will be focused and developed in the future. In addition, high grade refractories in China have great developing space and potential market.     

关于炼钢用耐火材料优化的几个问题

概述了现代炼钢生产发展与优化的主要特点。为适应这些发展特点的要求 ,提出了耐火材料向“更长寿、无污染、功能化”方向发展的必要性观点     

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.     

Optimization of steel production scheduling with complex time-sensitive electricity cost

Energy-intensive industries can take advantage of process flexibility to reduce operating costs by optimal scheduling of production tasks. In this study, we develop an MILP formulation to extend a continuous-time model with energy-awareness to optimize the daily production schedules and the electricity purchase including the load commitment problem. The sources of electricity that are considered are purchase on volatile markets, time-of-use and base load contracts, as well as onsite generation. The possibility to sell electricity back to the grid is also included. The model is applied to the melt shop section of a stainless steel plant. Due to the large-scale nature of the combinatorial problem, we propose a bi-level heuristic algorithm to tackle instances of industrial size. Case studies show that the potential impact of high prices in the day-ahead markets of electricity can be mitigated by jointly optimizing the production schedule and the associated net electricity consumption cost.     

交流和直流炼钢电炉UHP电极冶炼消耗比较与技术分析

介绍了超高功率交流和直流炼钢电炉的发展状况，对UHP电极在交流和直流电炉炼钢冶炼中的消耗特性进行了比较，同时就国内如何改善UHP电极的质量性能以满足电炉炼钢技术进步的需要作了概括的技术分析。     

PARALLEL SOLUTION OF DISJUNCTIVE MINLP PROBLEMS

In this paper, a system for parallel solution of large scale disjunctive optimization problems is presented. Disjunctive optimization problems occur in process engineering; both in production scheduling and in process synthesis. In general these problems are computationally very hard to solve.

This system combines the demands of process engineering optimization problems with the potential CPU-power of the computers connected to the Internet. The system is capable of using an arbitrary number of computers connected to the Internet for distributed solution of rigorous industrial optimization problems.     

Scheduling and energy – Industrial challenges and opportunities

Recent developments in energy markets, such as the increasing share of inherently volatile renewable power in the energy supply mix and the need of reducing carbon emissions while improving the production efficiency, make the operating environment of process industries more dynamic and complex. At the same time, continued advances in the mathematical programming and IT technologies open up new opportunities to tackle the related operational scheduling problems in a more integrated way at an ever larger scale. This paper discusses the industrial challenges arising from the deregulation of the electricity markets and stronger presence of unpredictable renewable energy sources. It gives a brief overview of methods currently available followed by set of real industrial case studies. The paper concludes with a discussion of the main challenges and opportunities relevant to the presented examples.     

转炉补炉砂制样方法的研究

通过对补炉砂种类、成型方法 ,以及焙烧温度、时间和方法等的研究 ,得到的转炉补炉砂制样方法如下 :将补炉砂试料加入 1 60mm× 40mm×60mm的三联耐热钢模中 ,稍作捣打使试料填满模具 ,然后将试料连同模具一起于 (90± 5)℃加热1 .5～ 2h ,待试料软化后将其捣实至高度不再下降 ;冷却后用模具隔板夹紧试料 ,放入匣钵中埋炭 ,于1 0 0 0℃焙烧 3h;最后切割、修整成外形尺寸符合检验要求的高 40mm左右的试样。对用该方法制备的试样进行了物理性能检测和分析 ,结果表明该制样方法是可行的     

鞍钢冶炼用耐火材料的现状及新进展

简述了鞍钢技术改造后的冶炼工艺概况,介绍了鞍钢冶炼用部分耐火材料的现状,并指出鞍钢现有部分耐火材料产品性能和使用寿命还不能完全满足钢铁生产的需要,今后需要在无碳钢包衬砖、钢包用滑板、非水系中间包涂料等方面开展进一步的研究。