Control Vector Parameterization‐Based Adaptive Invasive Weed Optimization for Dynamic Processes

A novel optimal approach named invasive weed optimization‐control vector parameterization (IWO‐CVP) for chemical dynamic optimization problems is proposed where CVP is used to transform the problem into a nonlinear programming (NLP) problem and an IWO algorithm is then applied to tackle the NLP problem. To improve efficiency, a new adaptive dispersion IWO‐based approach (ADIWO‐CVP) is further suggested to maintain the exploration ability of the algorithm throughout the entire searching procedure. Several classic chemical dynamic optimization problems are tested and detailed comparisons are carried out among ADIWO‐CVP, IWO‐CVP, and other methods. The research results demonstrate that ADIWO‐CVP not only is efficient, but also outperforms IWO‐CVP in terms of both accuracy and convergence speed.     

溶剂精制系统先进控制和优化

介绍带有前馈的模型预测控制算法，并对精馏塔的灵敏板温度进行控制。仿真实验和实际运行效果表明，该算法具有快速的跟踪性能和良好的抗干扰能力。     

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection(PSDIC) process of ethyl acetate and ethanol separation were investigated.The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced.This control structure did not require the control of the flowrate of the side stream.The dynamic controllability of PSDIC with partial heat integration(PHIPSDIC) was also explored.The improved control structure can effectively control ±20% feed disturbances.However,in industrial production,simple controller,sensitive and easy to operate,is the optimal target.To avoid the use of component controllers or complex control structure,the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased,albeit by incurring a slight rise in the total annual cost(TAC).This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.     

HPF法脱硫生产中副盐浓度的控制

从脱硫副盐的形成机理,探讨了控制副盐浓度的方法,并通过HPF法脱硫实际生产,分析了溶液的pH值、挥发氨含量、催化剂浓度等因素对副盐浓度的影响。     

Control Parameterization‐Based Adaptive Particle Swarm Approach for Solving Chemical Dynamic Optimization Problems

A control parameterization‐based particle swarm optimization (CP‐PSO) approach is presented which combines control parameterization with particle swarm optimization to solve dynamic optimization problems in chemical engineering. To improve search efficiency and convergence rate, a control parameterization‐based adaptive particle swarm optimization (CP‐APSO) approach is proposed, in which inertia weight and acceleration coefficients are updated according to population distribution characteristics. Three benchmark chemical dynamic optimization problems are explored as illustration. The results demonstrate that CP‐APSO is efficient for solving a general class of chemical dynamic optimization problems and CP‐APSO largely outperforms CP‐PSO on the convergence rate.     

网络化动态矩阵控制及在倒立摆控制中的应用

针对不确定有界长时延网络控制系统,研究动态矩阵控制(DMC)算法及其稳定性问题。首先基于多输入多输出状态空间模型,推导针对长时延网络化控制系统的DMC算法;然后,利用Lyapunov稳定性理论和线性矩阵不等式方法,给出闭环控制系统渐近稳定的充分条件;最后,通过对倒立摆的实时控制验证笔者算法的有效性。     

Dynamic simulation and control of auto-refrigerated CSTR and tubular reactor for bulk styrene polymerization

Dynamic simulation and control of a two-stage continuous bulk styrene polymerization process is developed to predict the performance of auto-refrigerated CSTR and tubular reactors. The tubular reactor is subdivided into three temperature-control jacket zones. In this paper temperature control of auto-refrigerated continuous stirred tank reactor and tubular reactor are carried out, simultaneously. Two strategies are proposed for the control of tubular reactor. At the first strategy the controlled variable is jacket temperature and in the second strategy the controlled variable is the reactor temperature at the exit of each section. The set points for polymer grade transition are obtained using optimization of reactors temperatures via genetic algorithm (GA). Simulation results show that both of the control strategies are successful but second strategy has better performance in the control of polymer properties in the presence of disturbance and model mismatch.     

Plant-wide control for the economic operation of modified single mixed refrigerant process for an offshore natural gas liquefaction plant

The marine operation of floating liquefied natural gas (FLNG) demands process compactness, flexibility, simplicity of operation, safety, and higher efficiency. The modified single mixed refrigerant (MSMR) process satisfies the FLNG process requirements and is accepted as a suitable technology for FLNG operation. The aim of this study was to develop a plant-wide control structure or strategy that can sustain the economic efficiency of the MSMR process. The NGL recovery and liquefaction units were integrated in the MSMR process to provide a compact plant structure with an efficient operation. Steady-state optimality analysis was intensively conducted in a rigorous dynamic simulation environment to determine the correct variable to sustain the economic efficiency of MSMR process. The results showed that the flow rate ratio of heavy and light mixed refrigerant (HK/LK ratio) is a promising self-optimizing controlled variable. Controlling this variable can sustain the MSMR optimality, even when the process is operated under off-design operating conditions or in the presence of disturbances. Based on the control structure tests, the control configuration with the HK/LK ratio loop showed excellent performance, maintaining the process stability against a range of disturbances. The proposed approach can also be applied to any cryogenic liquefaction technology for determining a possible optimizing controlled variable.     

应用软计算优化气辅注射成型工艺

气体辅助注射成型由于气体的引入使工艺更为复杂,增加了工艺变量,参数选取更为困难。本文基于CAE数值模拟试验结果,采用软计算方法,集成人工神经网络和生物进化遗传算法优化成型工艺,实现了气体辅助注射成型试验样品气体穿透长度的最大化。数值模拟与试验结果一致     

用于过程故障诊断的自适应kernel学习网络分类器

提出一种统一的最小二乘kernel学习框架,将自适应kernel学习（AKL）网络辨识器推广为分类器,用于化工过程的故障诊断。推导了AKL分类器在向后缩减和向前增长两种情况下的递推算法,实现了对记忆样本长度的控制。该分类器无需利用历史故障数据,即可进行在线学习并建立过程诊断模型。通过对Tennessee Eastman（TE）过程的5种典型故障的诊断分析,验证了该方法的有效性。     

Dynamic Matrix Control of a Bubble‐Column Reactor for Microbial Synthesis Gas Fermentation

A spatiotemporal metabolic model of a representative syngas bubble‐column reactor was applied to design and evaluate dynamic matrix control (DMC) schemes for regulation of the desired by‐product ethanol and the undesired by‐product acetate. This model was used to develop linear step response models for controller design and also served as the process in closed‐loop simulations. A 2 × 2 DMC scheme with manipulation of the liquid and gas feed flows to the column provided a superior performance to proportional integral (PI) control due to slow process dynamics combining the multivariable and constrained nature of the control problem. Ethanol concentration control for large disturbances was further improved by adding the flow of a pure hydrogen stream as a third manipulated variable. The advantages of DMC for syngas bubble‐column reactor control are demonstrated and a design strategy for future industrial applications is provided.     

The multi-period optimisation of an amine-based CO2 capture process integrated with a super-critical coal-fired power station for flexible operation

In this work, we present a model of a super-critical coal-fired power plant integrated with an amine-based CO₂ capture process. We use this model to solve a multi-period dynamic optimisation problem aimed at decoupling the operation of the power plant from the efficiency penalty imposed by the CO₂ capture plant, thus providing the power plant sufficient flexibility to exploit price variation within an electricity market. We evaluate four distinct scenarios: load following, solvent storage, exhaust gas by-pass and time-varying solvent regeneration. The objective is to maximise the decarbonised power plant's short run marginal cost profitability. It is found that while the solvent storage option provides a marginal improvement of 4% in comparison to the load following scenario, the exhaust gas bypass scenario results in a profit reduction of 17% whereas the time-varying solvent regeneration option increases the profitability of the power plant by 16% in comparison to the reference scenario.     

Dynamic process intensification: Fundamentals and implementation to ternary distillation

Distillation remains a key technology for separating liquid mixtures. Its versatility comes with the disadvantage of high energy consumption. We previously used empirical arguments to introduce dynamic process intensification (DPI) as a strategy for improving the energy efficiency of binary distillation. In this article, we focus on ternary distillation; we begin by providing a rigorous basis for DPI, then formulate the problem of identifying the operating states for DPI as a nonlinear optimization problem. Via an extensive case study considering a hydrocarbon mixture, we demonstrate that reboiler energy use can be reduced by more than 2.3% relative to an equivalent column operating at steady state. We prove that this result is due to the fact that DPI aims to satisfy product flow and quality constraints on average in time, affording broader opportunities for optimizing column economics than steady-state operation, where constraints are met strictly at all times.     

A wet process technology applied to jojoba seed to obtain oil and detoxified protein meal

An industrial wet process to obtain oil and meal from jo-joba was set up. The process sequence consists of breaking the seeds, homogenizing with water of suitable pH and temperature, and centrifuging to accomplish separation into oil, process water and wet meal. Oil is obtained with a yield of 70–75% and requires no supplementary refining treatment for the industrial purposes for which it is destined. The meal obtained is devoid of the toxic components simmondsin and simmondsin-2′ ferulate, and the protein content may be considered unchanged. The procedure contemplates a drying treatment for the meal with a view to using it as animal feed. This system is simple, economical and flexible in use.     

浅淡如何控制压力容器焊接质量

压力容器是一种特殊设备,其制造过程中的焊接质量控制尤为关键.认为只有建立完善的焊接质量控制系统,才能生产出合格的压力容器.从焊接材料、焊接工艺、焊接检验等几个方面来阐述怎样控制焊接质量.     

动态过程钢坯高温防氧化技术

概述了国内外钢坯高温防氧化涂料的研究现状。分析了动态过程钢坯高温防氧化涂料的技术要求。介绍了一种自主开发的动态过程钢坯高温防氧化涂料的应用状况。指出钢坯高温防氧化技术研究对减少钢材高温损耗、降低能源、提高生产效率和经济效益有重要的现实意义。     

A non-Gaussian pattern matching based dynamic process monitoring approach and its application to cryogenic air separation process

Principal component analysis (PCA) based pattern matching methods have been applied to process monitoring and fault detection. However, the conventional pattern matching approaches do not specifically take into account the non-Gaussian dynamic features in chemical processes. Furthermore, those techniques are more focused on fault detection instead of fault diagnosis. In this study, a non-Gaussian pattern matching based fault detection and diagnosis method is developed and applied to monitor cryogenic air separation process. First, independent component analysis (ICA) models are built on the normal benchmark and monitored data sets along sliding windows. The IC subspaces from the benchmark and monitored data are then extracted to evaluate the non-Gaussian patterns and detect process faults through a mutual information based dissimilarity index. Further, a difference subspace between the two IC subspaces is computed to characterize the divergence of the dynamic and non-Gaussian patterns between the benchmark and monitored data. Subsequently, the mutual information between the IC difference subspace and each process variable direction is defined as a new non-Gaussian contribution index for fault identification and diagnosis. The presented approach is applied to a simulated cryogenic air separation plant and the monitoring results are compared against those of PCA based pattern matching techniques and ICA based monitoring method. The application study demonstrates that the developed non-Gaussian pattern matching approach can effectively monitor the complex air separation process with superior fault detection and diagnosis capability.     

Dynamic modelling,simulation and optimization of an extractive continuous alcoholic fermentation process

The conventional alcoholic fermentation is a typical inhibitory process, leading to low productivity and yield. The ethanol produced inhibits yeast cells, causing a reduction in the alcohol production rate and cell growth rate. In this work, modelling and simulation have shown that continuous extractive fermentation, coupling a fermenter with an extractive vacuum flash chamber, is technically possible. In this case, the ethanol is partially removed, increasing drastically the productivity. Additionally, temperature control can be performed without using heat exchangers. The optimization was carried out using the method of factorial design and response surface analysis, leading to the determination of the most relevant variables, which were: 1.2 h residence time, 0.4 flash recycle rate, 180 g dm⁻³ sugar concentration and 0.35 cell recycle rate. The results, using optimized variables, were 98% conversion and 23 g dm⁻³ h⁻¹ productivity, which represent a three times higher productivity than in a conventional continuous process. © 1999 Society of Chemical Industry     

Control structure design of an industrial crude terephthalic acid hydropurification process with catalyst deactivation

Purified terephthalic acid (PTA) is a fundamental raw material for polyester and textile industry. The p-xylene oxidation process and crude terephthalic acid (CTA) hydropurification process are the two main sections of industrial PTA production. 4-Carboxybenzaldehyde is a byproduct of the first section that can lower the polymerization rate and the average molecular weight of the polymer. In this work, an improved complete plant dynamic model of the second section, CTA hydropurification with catalyst deactivation, was developed based on Aspen Dynamics. The present contribution considered the performance of the proposed catalyst deactivation model (Azarpour and Zahedi, 2012). Moreover, we designed a control structure for this process with catalyst deactivation, and the performance of the resulting control structure was analyzed using several criteria. Results showed that the proposed system provides a better control system and higher profit for the process.