先进控制技术在硫磺回收装置中的应用

运用多变量预测控制技术建立硫磺回收预测模型,开发并实施基于APC-Suite高级多变量预测控制软件的齐鲁石化硫磺回收先进控制系统。实际运行结果表明:该系统投运后,提高了装置操作的平稳率和安全性,降低了装置能耗。     

多变量预测控制技术在煤化工企业的应用

多变量预测控制技术作为目前世界上最先进的控制技术之一,可保证煤化工装置平稳运行、降低能耗、提高产品质量和收率,该技术的成功应用无疑对煤化工企业缓解压力有很大帮助。介绍了多变量预测控制技术及其在煤化工合成氨系统中的应用。     

乙醛生产与市场

据英国Ｔｅｃｎｏｎ咨询公司报道 ,1998年世界乙醛生产能力为 30 7万ｔ/ａ ,产量为 2 0 8万ｔ ,开工率仅为 67 8%。世界近 75%的乙醛用于生产醋酸、醋酸酐和醋酸酯。而当这些下游衍生物产品的需求处于增长之时 ,由于其新生产工艺废弃了旧的乙醛技术 ,使乙醛的需求增长趋于饱和。Ｔｅｃｎｏｎ预测 2 0 0 1～ 2 0 0 7年间世界乙醛的消费量将萎缩 ,平均每年下降 1 8%,同期将关闭一些旧的生产装置 ,产能平均每年下降 2 3%。实际上 ,全球乙醛装置正处于新老交替时期 ,乙醛产能基本保持稳定。Ｃｅｌａｎｅｓｅ是欧洲最大的乙醛生产商。最近该…     

先进控制技术在乙烯装置分离单元的应用

对过程控制中的软测量技术和多变量预测技术进行了讨论,并对软测量技术和多变量预测技术的基本概念进行了解释,综述了软测量技术和多变量预测技术在乙烯装置分离单元的丙烯精馏塔和碳二加氢反应器中的应用。     

多变量控制方式在液氮洗工艺中的应用

针对液氮洗装置的工艺特点,通过对合成氨装置生产工艺和过程控制以及历史数据的采集分析,对被控变量进行预测控制与精准控制,保证被控变量在最优区间运行,成功将多变量控制方式应用于合成氨装置。不仅解决了装置多变量耦合性问题,也解决了氢氮比控制滞后问题,减小工艺参数波动,提高装置运行的稳定性。     

乙醛回收装置的能耗分析及节能措施

介绍了现有乙醛回收装置的工艺流程,对各工段单元的能耗进行了分析和计算,有针对性地提出了优化节能措施。该措施实施后,能够提高乙醛和乙二醇的收率,降低乙醛回收装置的能耗和聚酯装置的运行成本,降低污水处理站的处理负荷。     

先进控制系统在PX氧化反应过程中的应用

洛阳石化PTA装置应用DMC plus先进控制技术,在PX氧化反应过程中成功建立多变量预测系统,先进控制投用率达到99.5%以上,该系统优化了TA产品品质控制和原辅料消耗,使关键被控变量标准偏差下降20%以上,同时也使装置的乙酸单耗下降0.9 kg。     

先进控制技术在纯碱生产碳化过程中的应用

纯碱生产装置中的碳化塔既是多相反应器又是多步结晶器,其中包含了吸收、反应、多相流、传热和传质等多种复杂的物理、化学过程。本文以某纯碱厂碳化系统为背景,将模型预测控制软件应用于5组共25座碳化塔中,开发了一个包含上百个被控变量、操纵变量和干扰变量的多变量预测控制器来解决该碳化系统的约束多变量控制问题。工业应用结果表明：模型预测控制软件能够确保碳化系统长期在最佳状态运行,进而降低物料消耗、改善产品质量和节省操作费用,使生产效益得到优化。     

关于酯化水温度对乙醛装置分离效果的研究

为了降低聚酯酯化反应和缩聚反应酯化水的化学需氧量(COD),节约处理废水成本,建立了乙醛回收装置,回收酯化水中的乙醛和乙二醇。试验发现,酯化水温度的变化对乙醛装置分离效果影响较为明显,通过调整温度,提高了乙醛和乙二醇回收量,每年可多回收50 t乙醛和90 t乙二醇。     

先进控制技术在戊烷精分装置上的应用与效果分析

通过对5×104t/a戊烷精分装置运行现状分析,研究了影响该装置平稳运行和产品收率的因素,引进中控APC-Adcon高级多变量鲁棒预测软件,实现了对戊烷精分装置的先进控制,取得了满意的控制效果和显著的经济效益。     

Advantage of Low‐Cost Predictive Control: Study Case on a Train of Distillation Columns

The process of enriching the ¹³C isotope, performed in trains of cryogenic distillation columns, exhibits large settling times, nonlinearities, large dead‐times, and are difficult to model precisely. Such equipment has been developed in Romania, with concentration increasing up to 70 %. A control analysis for a single unit has already been done including a decentralized multivariable PI controller and two decoupling control algorithms based on the internal model control (IMC) approach. Here, a multivariable predictive controller, the extended prediction self‐adaptive controller is proposed. The simulation results, considering significant modeling errors, demonstrate that this represents a more suitable choice than the previously designed strategies. Comparisons are included to support this idea.     

Control of a distillation column using self-tuning regulators

Self-tuning regulators were applied to the multivariable control of a pilot distillation unit. Both the top and the bottom product compositions were simultaneously controlled. The multivariable interactions were compensated for by different strategies. It was shown that a proper choice of the control variables made it possible to use a regulator with a smaller number of parameters. The evaluation of the results shows that the self-tuning regulator is a valuable tool in multivariable control of distillation columns.     

Control of a distillation column using self-tuning regulators

Self-tuning regulators were applied to the multivariable control of a pilot distillation unit. Both the top and the bottom product compositions were simultaneously controlled. The multivariable interactions were compensated for by different strategies. It was shown that a proper choice of the control variables made it possible to use a regulator with a smaller number of parameters. The evaluation of the results shows that the self-tuning regulator is a valuable tool in multivariable control of distillation columns.     

Dynamic behavior and operational aspects of heat-integrated distillation processes

Complex configurations of distillation columns have been shown to consume less energy than simple configurations. These complex configurations mainly results from two considerations: either a feed split, where the condensing vapor from the top of the high pressure column is used to heat the reboiler of the low pressure column, or the overheads from a high pressure column in a distillation train used to reboil a column under lower pressure. Industrial experience shows that very often in these configurations there is still incentive for more energy reduction simply because of inefficient control. The energy integration increases the control loop coupling the system, so that the operating strategy for the columns is no longer apparent. Therefore, the dynamic behaviour and the operational constraints of such systems become very important. The use of rigorous dynamic model of the processes is an essential instruments to pursue the goal of good and reliable process control Such models allow the engineer to realistically simulate the process with the desired control system in place and to analyze the effects of equipment sizing, hest integration, and disturbances. Variable pairing proved is used to illustrate that effective control of energy-integrated distillation columns can be achieved by proper selection of manipulated variables and pairing them correctly with control variables. Hints will also be given, when multivariable predictive control schemes should be used.     

Application of the method of inequalities to the multivariable control of binary distillation columns

The method of inequalities is used to design controllers for dual quality control of four binary distillation columns whose top and bottom compositions are controlled by manipulating reflux rate and steam. Two types of multivariable proportional-plus-integral controllers are designed and the performance of the system with these controllers is compared with that of non-interacting control. The results of implementing the simpler controller, which is represented by a diagonal matrix, on a computer-controlled packed distillation column are also presented.     

径向基函数神经网络在精馏塔软测量中的应用

精馏塔是化工过程中最常用的操作单元 ,具有很强的非线性和时变性 ,故很难进行机理建模分析或常规在线实时控制 ,因而提出一种基于径向基函数神经网络的优化控制方案。通过利用径向基函数神经网络建立精馏塔产品质量的软测量模型 ,将软测量结果与现场数据比较 ,表明本模型具有比较准确的跟踪显示效果 ,并将软测量模型进一步应用到精馏塔的回流量和釜液排放量的优化控制中     

Applying Model Predictive Control to Dividing Wall Columns

The technology of dividing wall columns can offer enormous energy savings compared to common distillation columns and configurations. The technology of model predictive control is also advantageous since such a controller minimizes the future deviation of the predicted controlled variable from the reference point. The practical application of model predictive controllers for dividing wall columns is still limited due to limited experience with high interactions among the process variables. The scope of this work is the development and analysis of a method for the design of model predictive controllers for dividing wall columns. An experimental investigation verifies the practicability of the applied approach. The methods generated are transferable to other applications. Thus, the industrial acceptance of model predictive controllers for dividing wall columns is enhanced.     

OPERATING PROBLEMS OF DISTILLATION COLUMNS: A DISCUSSION

A qualitative knowledge of how a continuous distillation column is expected to react to a physical parameter variation is often required, both in simulation and in practical operation. The topic is discussed in this paper with the aim to indicate some simple predictive rules concerning the steady-state variations, both under open- and closed-loop control. The binary distillation in conventional and non-conventional columns is examined in detail; some indications are also given for the multicomponent distillation in conventional columns. Geometrical constraints and asymptotic solutions are the basis for the adopted approach.     

Design and synthesis of multicomponent thermally coupled distillation flowsheets

The design and synthesis of thermally coupled distillation flowsheets for separations of five-component mixtures are studied. Four types of possible configurations are identified when simple and complex columns are both considered in a flowsheet. A universal design procedure is developed for design of any types of the identified configurations based on the abstraction of the three basic units in the flowsheets. Two examples demonstrated that this shortcut design method can be used in design of any types of the identified multicomponent thermally coupled distillation flowsheets, as well as give very good initializations for rigorous simulation of such configurations. Moreover, with a proposed computer representation of all the types of the feasible configurations, a synthesis algorithm is developed for synthesizing of multicomponent complex distillation flowsheets with both simple and complex columns. It is practical by the proposed methods for optimal design of multicomponent distillation systems in an extended search space to include the complex distillation flowsheets for industrial problems.     

Hydrodynamic continuum model for two-phase flow structured-packing-containing columns

A two-zone two-fluid one-dimensional model was developed for the prediction of the irrigated two-phase pressure drop and the total liquid holdup in gas-liquid countercurrent columns containing structured packings and operated in the pre-loading zone. The model is based on the volume-average mass and momentum balance equations and the double slit model approximation. The model parameters, i.e., the two b2ed Ergun constants, were estimated using gas flow three-dimensional computational fluid dynamics (CFD) within representative elementary units coupled with a combined mesoscale—microscale predictive approach to apprehend the aerodynamic phenomena occurring at the macroscale in structured-packing-containing columns. The two-fluid model proved powerful in the prediction of the column hydraulics under various operational conditions such as atmospheric scrubbing or high-pressure/temperature distillation conditions for the Flexipac, Mellapak, Gempak and Montz packings. The satisfactory results obtained highlighted the breadth of applicability of the proposed approach especially for new designs or for optimal rating of existing equipments. The model can also prove powerful in the simulation and design of new geometries for structured packings.