Robust Control Distillation Essay

Abstract— Distillation column is one of the most commonly found process in any chemical industries that is used for separation process. Distillation processes are most energy consuming processes. The high nonlinearity and dynamic behavior of the column make them hard to control. Designing of distillation column is also one of the most common challenging tasks. Different control strategies can be applied to control distillation process. The strong interactions between each of the manipulated variables and both controlled variables require MIMO control design techniques. Robust control of distillation column provides robust stability and robust performance.

Key words—Distillation Column, Robust Control, Manipulated variable, Controlled variable

The simulation is carried out by the Simulink model nls col.mdl using the nonlinear plant model given in this.

The Simulink model of the distillation column control system shown in below fig allows carrying on a number of simulations for different set points and disturbances. Note that the inputs to the controller are formed as difference between the values of the corresponding variables and their nominal (steady state) values used in the linearization. As opposite, the controller outputs are added to the corresponding nominal inputs in order to obtain the full inputs to the nonlinear model of the column.

The nonlinear system simulation is done for the following reference and disturbance signals. At t = 10 min the feed rate F increases from 1 to 1:2, at t = 100 min the feed composition zF increases from 0:5 to 0:6 and at t = 200 min the set point in yD increases from 0:99 to 0:995.
The time response of the distillate yD for the case of the reduced-order µ-controller is given in Figure. It is seen from the Figure that the disturbances are attenuated well and the desired set point is achieved