Abstract
Since 1968, Chiyodakako Kensetsu, Fujidenki and Fujitsu have been researching for digital control of chemical processes.
In this project, two DDC systems have been developed, (the CPU of one system is FACOM 270-25 and the CPU of the other is FACOM R), and for an example of advanced control of a DDC system, the optimal control of a distillation column which uses state variables has been investigated. The summary of the paper is as follows.
(1) Result of experiments of static characteristics and dynamic characteristics of distillation column, and corresponding results of digital computer simulation. They have clear nonlinearity.
(2) Important equations of mathematical simulation model and linearized system equation for the application of optimal control theory.
(3) Method of calculation of optimal feedback gain and accuracy of solution of Riccati's equation.
(4) Ratio of the weights in performance index of control variables to the weights of controlled variables varies control action, but there was no convenient method to fix the ratio.
(5) Direction of control variable (reflux flow in this case) of optimal control was different from the direction of conventional top-bottom control.
(6) As the control has proportional action only, application of this control is limited.
(7) All the process variables which appear in the system equation must be fed back.
Figures show static temperature distribution and transient responses of experiments or digital computer simulation.
