Integration of Process Design and Control

计划研究项目的总体目标是过程设计和过程控制的集成。具体地说，开发经济上可行的方法，用于过程的设计阶段，以分析可控性/可操作性问题。PI计划着眼于三个领域：(1)工艺结构对工艺可控性/可操作性的影响，(2)暂态性能与工艺参数(可从稳态数据获得)的相关性，以及(3)使用成分测量来改善精馏塔控制。化工厂可以被视为是从少量的基本结构中建立起来的。无论所涉及的一个或多个单元的类型如何，这种结构都会影响整体工艺性能。一组定义的基本结构可能包括串并、重组和循环结构。由于经济原因，后者在化学工业中被广泛使用，并且会对系统的开环和闭环系统性能产生重大影响。这项研究的目的是确定回收处理配置对流程可操作性/可控性的影响，并将这种影响与设计参数相关联。将用两个例子来说明由循环结构引起的控制问题：蒸发器配置和包括蒸馏塔、热交换器和工业反应器的循环系统。控制系统的性能将与关键的设计变量有关，如吞吐量、持有率、热集成以及质量和/或能量的循环比率。PI开发了一种使用无量纲数的方法，称为相对扰动增益(RDG)，当与计算的相对增益(RGA)结合使用时，可以基于稳态信息来评估过程的暂态行为。本质上，RDG衡量的是多环路系统中其他环路的闭合是否在所考虑的环路的瞬时性能方面产生有利或不利的相互作用。最终，PI计划将相关参数与关键设计变量相关联，并将RGA、RDG和测量的峰值属性集成到专家系统中。

The overall goal of the planned research projects is the integration of process design and process control. Specifically, the development of economically viable approaches to be used at the design stage of a process to analyze for controllability/operability problems. The PI plans to look at three areas: (1) the effect of process structure on process controllability/operability, (2) correlation of transient performance with process parameters (available from steady state data) and (3) the use of composition measurements to improve distillation column control. Chemical plants can be viewed as being built up from a small number of basic structures. Irrespective of the type of unit or units involved, this structure affects overall process performance. A defining set of basic structures might include series-parallel, recombining, and recycle structures. The latter are widely used in the chemical industry for economic reasons and can have a drastic effect on both the open loop and the closed loop performance of a system. The goal of this research is to determine the effect that recycle processing configurations have on process operability/controllability and to correlate this effect with design parameters. Two examples will be used to illustrate the control problem caused by recycle structures: evaporator configurations and recycle systems involving distillation towers, heat exchangers, and industrial reactors. Control system performance will be related to key design variables such as throughput, holdup, heat integration, and recycle ratio of mass and/or energy. The PI has developed a method using a dimensionless number called the relative disturbance gain (RDG) which when used in conjunction with the calculated relative gain (RGA) can be employed to assess a process' transient behavior based on steady state information. In essence what the RDG measures is whether the closure of other loops in a multiloop system produces favorable or unfavorable interaction in terms of transient performance of the loop under consideration. Ultimately the PI plans to relate correlating parameters to key design variables and to integrate RGA, RDG and measured peak properties into an expert system.