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In this paper we present a decomposition strategy for solving large scheduling problems using mathematical programming methods. Instead of formulating one huge and unsolvable MILP problem, we propose a decomposition scheme that generates smaller programs that can often be solved to global optimality. The original problem is split into subproblems in a natural way using the special features of steel making and avoiding the need for expressing the highly complex rules as explicit constraints. We present a small illustrative example problem, and several real-world problems to demonstrate the capabilities of the proposed strategy, and the fact that the solutions typically lie within 1–3% of the global optimum. 相似文献
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Florian FabreGilles Hétreux Jean-Marc Le LannPascale Zaraté 《Computers & Chemical Engineering》2011,35(10):2098-2112
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. 相似文献
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Yeong Ho Yoo HeuÏ Seok Yi Yeong-Koo Yeo Myung Kil Kim Hong Suk Yang Kwang Pil Chung 《Korean Journal of Chemical Engineering》1996,13(4):384-392
A systematic method for analysis and design of plant-wide energy distribution systems is proposed to minimize the net cost
of providing energy to the plant. The method is based on the steady-state modeling and simulation of steam generation process
and steam distribution network. Modeling of steam generation process and steam distribution network were performed based on
actual plant operation data. Heuristic operational knowledges are incorporated in the modeling of steam distribution network.
Newton’s iteration method and a simple linear programming algorithm were employed in the simulation. The letdown amount from
superheated high-pressure steam (SS) header and the amount of SS produced at the boiler showed good agreement with those of
actual operational data. 相似文献
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Refrigeration system holds an important role in process industries. The optimal synthesis cannot only reduce the energy consumption, but also save the production costs. In this study, a general methodology is developed for the optimal design of refrigeration cycle and heat exchanger network (HEN) simultaneously. Taking the heat integration between the external heat sources/sinks and the refrigeration cycle into consideration, a superstructure with sub-coolers is developed. Through defining logical variables that indicate the relative temperature positions of refrigerant streams after sub-coolers, the synthesis is formulated as a Generalized Disjunctive Programming (GDP) problem based on LP transshipment model, with the target of minimizing the total compressor shaft work in the refrigeration system. The GDP model is then reformulated as a Mixed Integer Nonlinear Programming (MINLP) problem with the aid of binary variables and Big-M Constraint Method. The efficacy of the process synthesis model is demonstrated by a case study of ethylene refrigeration system. The result shows that the optimization can significantly reduce the exergy loss as well as the total compression shaft work. 相似文献
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An overview of dynamic optimization problems with hybrid systems embedded is presented. The control parameterization approach is examined in detail, where the possibility of mode switching within the hybrid system causes nonsmoothness in the Master problem, thus invalidating gradient based solvers. To handle this, a decomposition approach is proposed that divides the general problem into smooth subproblems. The subproblem of determining the optimal mode sequence given fixed transition times is considered for continuous time linear time varying hybrid systems. A mixed-integer reformulation of the problem is proposed that retains the linear structure of the embedded hybrid system. A deterministic branch-and-cut framework incorporating outer approximation cuts and a dynamic bounds tightening heuristic is then employed to solve the nonconvex mixed-integer problem to guaranteed global optimality with a finite number of iterations. It is shown that the dynamic bounds tightening heuristic can have a dramatic effect on accelerating convergence of the algorithm. Future directions for research are also discussed, including the application of recent developments in semi-infinite programming for the formal safety verification of processes under uncertainty. 相似文献
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The optimal design of a compression refrigeration system (CRS) with multiple temperature levels is very important to chemical process industries and also represents considerable challenges in process systems engineering. In this paper, a general methodology for the optimal synthesis of the CRS, which simultaneously integrates CRS and Heat Exchanger Networks (HEN) to minimize the total compressor shaft work consumption based on an MINLP model, has been proposed. The major contribution of this method is in addressing the optimal design of refrigeration cycle with variable refrigeration temperature levels. The method can be used to make major decisions in the CRS design, such as the number of levels, temperature levels, and heat transfer duties. The performance of the developed methodology has been illustrated with a case study of an ethylene CRS in an industrial ethylene plant, and the optimal solution has been examined by rigorous simulations in Aspen Plus to verify its feasibility and consistency. 相似文献
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The electrochemical generation of ozone by Ni/Sb-SnO2 anodes immersed in 0.5M H2SO4 was assessed in both flow and recycle systems using the same electrochemical cell. The anodes were found to exhibit current efficiencies of up to 50%?for ozone generation under flow conditions at room temperature, with an optimum mole ratio in the precursor solutions of ca. 500:8:3 Sn:Sb:Ni and optimum cell voltage of 2.7V. A comparison of the data obtained under flow and recycle conditions suggests that the presence of ozone in the anolyte inhibits its formation. The minimum electrical energy cost achieved, of 18 kWh kg?1 compares favorably with estimated costs for Cold Corona Discharge generally reported in the literature, especially when the very significant advantages of electrochemical ozone generation are taken into account. 相似文献
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This paper presents a systematic approach for the synthesis of the heat recovery network in total site using a Mixed Integer Linear Programming model. This model returns a near-to-optimal network configuration with minimum utility cost while allows to select geographically closest matches. The Heat Load Distribution is the subproblem of the network design and has been reported to be quite expensive to solve for large-scale problems. The computational complexity of HLD resides in the number of streams and the feasible networks. An additional challenge, raising particularly in industrial problems, has been the intermediate heat transfer network which aggravates the combinatorial complexity. The presented methodology deals with those difficulties by priority consideration based on the location of process units. It helps significantly reducing the computational time and also comes with a realistic network sketch with respect to the plant layout. Several examples are discussed along with a real industrial case study. 相似文献
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通过认真分析聚乙烯醇车间醋酸乙烯和聚乙烯醇两套独立醋酸精馏系统的特点,优化醋酸精馏系统的运行方式,实现流程再造,将两套生产装置的醋酸精馏系统优化整合,并合理利用醋酸乙烯装置精馏塔采出精醋酸的热能,从而有效降低装置能耗。 相似文献
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《Journal of the European Ceramic Society》2019,39(16):5236-5242
Ca1-xSrxTi1-yZryO3 (0.40 ≤ x ≤ 0.60, 0.1 ≤ y ≤ 0.4) ceramic samples were fabricated by conventional solid state method. The microstructure of ceramic samples were studied by XRD and SEM, and the influence of Zr4+ doping on the electric properties and energy storage performances were systematically studied. The results showed that the introduction of Zr4+ results in an inhibition of interfacial polarization and enhancement of grain boundary barrier effect. Ca0.5Sr0.5Ti1-yZryO3 ceramic samples exhibit excellent energy storage properties, with breakdown strength being on the order of 390 kV/cm versus 280 kV/cm for the counterpart Ca0.5Sr0.5TiO3 ceramic samples, together with energy efficiency above 95%. Meanwhile, a maximum breakdown strength of 390 kV/cm, a high energy storage density of 2.05 J/cm3 and an ultrahigh energy efficiency of 85% at high temperature of 125 ℃ were obtained in the sample with y = 0.1 as well, indicating it as a good candidate for linear energy storage fileds. 相似文献
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The work reported in this paper investigated the observation that high concentrations of ozone in the electrolyte inhibits the electrochemical ozone evolution process at Ni/Sb-SnO2 anodes in aqueous sulfuric acid. We show that inhibition does indeed take place and that this inhibition does not affect the current density and hence appears to reflect an increase in the ratio of O2 to O3 evolved. A possible mechanism for the inhibition is proposed. It was found that Celgard 2400 membrane was an acceptable alternative to Nafion in the divided electrolysis cell employed. 相似文献
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针对渣液转换器中零件的扭曲和变形,经过改造将电动操作系统改造为气动操作系统,并增加了行程限位器和信号反馈系统,取得了良好的经济效益和社会效益。 相似文献
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The forecasted shortage of fossil fuels and the ever-increasing effect of greenhouse gas (GHG) emissions on global warming and environmental stability are two international problems with major technical, economic and political implications in the 21st century. Therefore, it is urgent to restructure present energy production and utilization systems in order to ensure that fossil fuels are used with high efficiency and low to zero emissions. Polygeneration energy systems combine power generation and chemical fuel synthesis in a single plant (producing both electricity and fuels) and thus provide a promising alternative pathway towards achieving sustainable and flexible economic development. Mixed-Integer programming (MIP) is useful in constructing long-term decision models that are suitable for investment planning and design of polygeneration infrastructure systems. This paper presents a model for the investment planning of a polygeneration energy system and a case study addressing a system for production of methanol and electricity in China during the period from 2010 to 2035. It contains five different feedstocks and twelve polygeneration technologies. 相似文献
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乙烯装置急冷系统能量回收工艺特点分析 总被引:1,自引:0,他引:1
乙烯装置急冷系统接收来自炉区的高温裂解气,为降低乙烯装置能耗,必须尽可能回收裂解气中的热量。文中针对KBR乙烯流程,介绍了乙烯装置急冷系统能量逐步回收的过程及其工艺特点。 相似文献