Controls used to optimize the ideal binary distillation column operation

Ideal binary distillation column optimization depends on the process control principles of feedback, feedforward, and hill climbing methods. For particular continuous distillation operation (olefins purification) both method can be used simultaneously by the optimum operation parameters. Each method as it own different advantages and to finding out the best of it, is important task of the design engineer to develop a strategy for stable controlling. By choosing situation of a static model, we can easily develop a mathematical model for of distillations control system. By the help of a mathematical model, we can figure out the dependent and independent variable that are to be controlled and monitored.

Establishing a control system with two control variables is much easier than multi variables. Two variable control systems are,

  • Temperature and pressure control (feed, distillate and residue temperature and column pressure)
  • Dual quality control (Steam flow rate, reflux rate)

To optimize the ideal binary distillation column four-control valves are used for controlling the level and temperature variables.

Control valve

Controller

Quantity

Placements

Purpose

Global valve/ needle valve Level controller

2

1. Fitted at bottom line of the distillation column to withdraw bottom product 1. To maintain level at bottom section of the distillation column
2. Placed at the distillate outlet line 2. To maintain the level in reflux drum
Global valve Temperature controller

1

Fixed in the steam  input line to the reboiler For controlling the flow of steam input and maintain the distillation column temperature
Global valve Flow controller

1

Fixed in the reflux line To maintain the flow rate of reflux into the column
Diagram to optimize the ideal binary distillation column

Temperature, pressure, flow control for distillation column