基于一般模型控制的高纯内部热耦合精馏策略

内部热耦合精馏塔（ITCDIC）是精馏节能控制的一个前沿。本文提出了一种基于一般模型控制（GMC）的内部热耦合精馏塔的先控策略,以解决导致传统线性控制策略难以得到较好控制效果的高纯下内部热耦合精馏塔的非线性。以苯-甲苯物系作为研究实例,对所提出的高纯ITCDIC控制策略进行了详细研究。设定值改变和过程扰动下的控制品质表明了所提出的高纯ITCDIC的GMC控制策略的切实有效性。     

基于内模控制的内部热耦合精馏策略

精馏过程约占工业总能耗的1/3,其节能控制潜力很大。内部热耦合精馏(ITCDIC)是迄今为止所提出的节能效果最好(比常规精馏节能40%以上)却没有商业化的节能技术。主要原因在于该过程具有较强的非线性、复杂的动态特性以及耦合性,给控制方案的设计带来了极大的困难。通过建立更为精确的二阶内部模型,提出了一种有效的ITCDIC内模控制方案。实例研究结果表明,与传统控制方案PID相比,控制品质更加稳定可靠;同时,与目前国际上公开报道的最好结果相比,该控制方案有更广泛的操作域,鲁棒性更强。     

基于强酸当量的pH值前馈-自适应控制

对pH非线性过程的控制,在传统线性自适应控制的基础上,采用基于强酸当量的过程模型.引入一内嵌混合装置,并结合前馈及自适应控制方案,有效补偿了由于过程流成分和浓度变化引起的静差,具有良好的设定值跟踪性能.仿真结果表明,该方案能够有效克服中和曲线变动对控制性能带来的影响,具有良好的控制效果.     

非线性液位系统的反馈线性化控制

为了更好地研究非线性液位系统在工作点大范围变化时的控制问题,对A3000过程控制装置中非线性单容水箱的液位控制进行了研究。建立了精确的单容水箱模型,提出了一套基于传统PID控制的反馈线性化控制方案,并在Freelance 800F DCS中成功进行了组态和调试,验证了反馈线性化控制方案在非线性液位系统中的可行性和优越性。     

二异丁烯反应精馏生产过程控制策略设计

二异丁烯是一种重要的化工中间体,近年来研究者提出了以催化裂化C₄为原料、采用反应精馏技术同时生产高纯二异丁烯和汽油添加剂的新工艺。由于反应精馏过程中非线性程度高,稳定控制困难,使得采用反应精馏技术生产二异丁烯过程的控制策略研究较少。采用Aspen dynamic软件进行动态模拟,针对反应精馏生产二异丁烯过程开发了温度控制方案、组分温度联合控制方案和组分温度串级控制方案。对3个控制系统进行（±10）%的进料流量扰动和（±5）%组成扰动测试并进行对比。结果表明：组分温度串级控制方案在添加扰动的情况下依然保证了二异丁烯质量分数99%,三异丁烯质量分数小于10%以及异丁烯转化率大于99%的要求,并且最终稳定时间约5 h,具有更好的抗干扰性能。研究结果能够为二异丁烯产品的生产工艺工业化应用提供设计依据。     

基于Hammerstein模型的非线性系统辨识方法研究

工业大系统中Hammerstein模型的非线性系统,一般都是多输入多输出系统,具有大滞后、大惯性、时变性和强耦合性的特点,它的数学模型难于精确获得;且传统PID控制器无法使控制效果处于最佳状态的局限性.为了更加快速准确控制,使系统更加地稳定工作在最佳工作状态.利用分散辨识方法对Hammerstein模型的非线性系统进行...     

自适应广义一般模型控制

针对一般模型控制的缺点,提出了两种改进的自适应广义一般模型控制方法.它们把传统的一般模型控制推广到相对阶大于1 同时又具有时变参数的复杂非线性过程.第1种控制策略主要利用强跟踪滤波器直接在线估计时变参数,来修正过程模型;另一种方法是将所有干扰因素归结为输入等价干扰,通过估计它来实现对过程的前馈控制.仿真实验结果验证了所提出方法的有效性.     

离心压缩机变频与串级-分程控制方案的设计选用

针对某天然气处理厂离心压缩机变频调节存在的问题,设计了合理稳定的控制方案。实际测试表明:采用压力串级-分程控制方案能够有效稳定系统压力波动。     

基于加权深度支持向量数据描述的工业过程故障检测

传统支持向量数据描述（SVDD）方法本质上采用浅层学习框架,难以有效监控非线性工业过程的复杂故障。针对此问题,提出一种基于加权深度支持向量数据描述（WDSVDD）的故障检测方法。该方法一方面在深度学习框架下重新定义SVDD优化目标函数,构建基于深度特征的深度SVDD监控模型（DSVDD）,并利用核密度估计法计算监控指标的统计控制限;另一方面,考虑到深度特征的故障敏感度差异特性,在DSVDD监控模型中设计特征加权层,分别从静态和动态信息分析角度给出权重因子的计算方法,利用权重因子突出故障敏感特征的影响以提高故障检测率。应用于一个典型化工过程的测试结果表明,所研究的方法能够比传统SVDD方法更有效地监控过程中复杂故障的发生。     

递归核PCA及其在非线性过程自适应监控中的应用

PCA、PLS作为常用的多变量统计监控算法,一般适用于线性、定常的过程。针对实际工业过程的时变、非线性特性,提出了一种递归核PCA（RKPCA）方法用于非线性过程的自适应监控。RKPCA算法通过将递归奇异值分解推广到核空间,给出了核形式描述的递归KPCA算法,运算复杂度比KPCA明显降低,保证非线性监控模型能够在线更新。在Alstom工业燃气发生装置上的自适应监控表明,所提出的RKPCA算法能够及时跟踪非线性过程的时变特征,保证了监控模型的有效性。     

Generalized generic model control of high‐purity internal thermally coupled distillation column based on nonlinear wave theory

A new model‐based control strategy for the internal thermally coupled distillation column (ITCDIC) is presented. Based on the nonlinear wave theory that describes the nonlinear dynamics in the separation processes, a simplified nonlinear wave model is established that concerns both the wave propagation and the profile shape. An advanced controller (WGGMC) is formulated by combining the nonlinear wave model with a generalized generic model control (GGMC). Compared with a conventional generic model controller based on a data‐driven model (TGMC), and another wave‐model based generic model controller (WGMC) developed in our previous work, WGGMC exhibits the best performances in both servo control and regulatory control. Furthermore, WGGMC can handle a very‐high‐purity system of ITCDIC with top product composition of 0.99999, while the other two controllers fail to work. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4133–4141, 2013     

Nonlinear wave modeling and dynamic analysis of internal thermally coupled distillation columns

Internal thermally coupled distillation column (ITCDIC) is a frontier in the energy saving distillation research. It is well known for the complex dynamics, which challenge the establishment of an excellent reduced model for further control strategy design greatly. In this article, a physical approach of the ITCDIC process based on nonlinear wave theory is explored, where it is first discovered that traditional wave theory in conventional distillation columns (CDIC) could not be directly applied in ITCDIC, due to: First, the internal thermal coupling results in mole flow rates varying evidently over each stage, which not only makes the wave modeling of the wave phenomenon in ITCDIC more difficult but also makes wave dynamics greatly different between ITCDIC and CDIC; Second, an interesting wave phenomenon of ITCDIC is discovered that waves located in the rectifying section and stripping section travel under opposite tendencies when the steady state is disturbed by the step change of thermal condition q, one sharpens and the other is likely to spread synchronously, it means the movement of wave profiles in ITCDIC could not be simply described by shock wave velocity, which is usually used in wave modeling of CDIC; more seriously, shapes of the self‐sharpening wave profiles in ITCDIC change obviously during the traveling processes, which further reveals that shape influence on wave velocity has to be considered in the wave modeling of ITCDIC. A rigorous wave velocity and a natural wave velocity are derived, respectively, based on which, the detailed analyses of traveling wave characteristics are carried out. A novel wave velocity, based on the profile trial function which has been well developed by Marquardt, is further derived to consider the obvious change of profile shape. And a completed nonlinear wave model of ITCDIC is thereby established by combining the proposed wave velocity with thermal coupling relations and material balance relations. The benzene‐toluene system is illustrated as an example, where component concentration prediction and distinct dynamic characteristics are carried out in detail based on the proposed nonlinear wave models. The research results reveal the accuracy and validity of the proposed nonlinear wave model of ITCDIC. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Adaptive Robust Generic Model Control of High‐Purity Internal Thermally Coupled Distillation Column

The internal thermally coupled distillation column (ITCDIC) is a frontier in energy‐saving distillation research. The process inside a high‐purity ITCDIC is of great nonlinear dynamics, which trouble the conventional control schemes. A multivariable adaptive robust generic model control (ARGMC) is presented to solve the difficulties, where an ARX model is derived and a recursive least squares estimation (RLSE) method is introduced. The benzene/toluene system is studied as an illustrative example. The results of ARGMC are compared with the robust generic model control (RGMC) and traditional PID control in detail. The performances in both servo control and regulatory control confirm the accuracy and validity of ARGMC for the high‐purity ITCDIC process.     

Adaptive generalised predictive control of high purity internal thermally coupled distillation column

Internal thermally coupled distillation column (ITCDIC) is a frontier in the energy‐saving distillation researches. One of the bottlenecks to prevent the column from being commercialised is the difficulty in control design due to the high sensitivity to disturbances, strong asymmetric nonlinearity and inverse response especially under high purity. An adaptive multivariable generalised predictive control (AM‐GPC) strategy of ITCDIC process is proposed to solve the difficulties in high purity. The simulation results of AM‐GPC are compared with single input and single output GPC (S‐GPC), multivariable GPC (M‐GPC), modified IMC (M‐IMC) and traditional PID control in detail. The performances confirm the accuracy and validity of AM‐GPC for the high‐purity ITCDIC process. © 2011 Canadian Society for Chemical Engineering     

内部热耦合精馏塔的初步设计(I) 模型化和操作分析

引　言将热量从精馏段传到提馏段来实现节能是精馏过程节能的一种有效方法 ,即二次回流和蒸发[1](ＳＲＶ) .内部热耦合精馏塔 (ＩＴＣＤＩＣ)的热耦合机理仍是ＳＲＶ方法 ,但去掉了再沸器和冷凝器 ,具有较大的节能潜力 .它的研究只有近 1 0年的历史[2 ,3],目前 ,还没有见到详细的操作分析和设计优化的文献报道 ,只有一些较为相关的文献[4 ,5 ].本文对理想热耦合精馏塔进行了建模和操作分析 .1　模型化图 1是ＩＴＣＤＩＣ的示意图 .精馏段和提馏段被分为两个塔 .热耦合通过两段之间的热交换器来实现 .为了提供传热必须的推动力 ,精馏段将在较…     

内部热耦合精馏塔的初步设计(II) 控制分析和参数优化

Based on the previous design model, degrees of freedom analysis and transient analysis are carried out. A PID control model is proposed. The results show that ITCDIC is a self-regulating process, and could be operated smoothly with two PID controllers; the steady state design could be disassociate with the dynamic design. An optimization model of ITCDIC design parameters is derived, which can directly achieve the optimal design parameters providing the maximum energy savings and the product quality simultaneously. Benzene-toluene system is studied as an illustrative example.     

内部热耦合精馏塔基于非理想物系的最优评价

Internal thermally coupled distillation column(ITCDIC) is a frontier in energy saving distillation research. In this paper, the optimal assessment on the energy saving and the operating cost for ITCDIC of nonideal mixture is explored. An evaluating method is proposed, and the pertinent optimization model is then derived. The ethanol-water system is studied as an illustrative example. The optimization results show that the maximum energy saving in ITCDIC process is about 35% and the maximum operating cost saving in ITCDIC process is about 30%,as compared with a conventional distillation column(CDIC) under the minimum reflux ratio operating; the optimal operating pressure of the rectifying section is found to be around 0.25 MPa; the effects of the feed composition,operating pressure and the heat transfer rate on operation are also found and analyzed. It is revealed that ITCDIC process possesses high energy saving potential and promising economical prospect.     

内部热耦合精馏塔的初步设计(II) 控制分析和参数优化

引　言研究表明[1,2 ],控制和设计优化往往是节能方法实际应用中的主要困难 .关于二次回流和蒸发(ＳＲＶ)、Ｐｅｔｌｙｕｋ、热交换网络 (ＨＥＮ)等方法的控制设计已经有了大量的研究[3,4].这些研究方法可以借鉴到内部热耦合精馏塔 (ＩＴＣＤＩＣ)的控制研究上[5 ].本文对理想ＩＴＣＤＩＣ进行了自由度分析、暂态分析和ＰＩＤ控制研究 ,并进行了设计参数的优化和分析 .目前 ,尚未见到设计优化的文献报道 .1　自由度分析对于理想二元混合物 ,ＩＴＣＤＩＣ动态系统由6.5ｎ 1 0个独立方程 (ｅ)、 6.5ｎ 2 7个变量υ构成 ,系统的自由度为 ｆ =…     

Thermodynamic analysis, simulationand optimization on energy savings of ideal internal thermally coupleddistillation columns

Internal thermally coupled distillation columns (ITCDIC) are the frontier of distillation energy saving research. In this paper, a novel energy saving model of ideal ITCDIC and a simulation algorithm are presented,upon which a series of comparative studies on energy savings with conventional distillation columns are carried out. Furthermore, we present an optimization model of ideal ITCDIC, which can be used to achieve the maximum energy saving and find the optimal design parameters directly. The binary system of benzene-toluene is adopted for the illustrative example of simulation and optimization. The results show that the maximum energy saving of ITCDIC is 52.25% (compared with energy consumption of conventional distillation under the minimum reflux ratio operation); the optimal design parameters are obtained, where the rectifying section pressure and the feed thermal condition are Pr=0.3006 MPa and q=0.5107 respectively.