CENG 471 - Process Control Lab

Spring 2000

PART I: MATHEMATICAL MODEL

1. Develop a mathematical model that describes the transient operation of the 3 CSTR mixing system. Draw a block diagram of the control system and place in each block the appropriate transfer function. Compute the ultimate gain and ultimate period for this control system.
   
2. Design a feedback controller using all the methods you know that will give you PI or PID controllers for this process. Possible methods are:
   
   • Direct Synthesis method;
   • IMC method;
   • ITAE performance index for load and setpoint changes;
   • Ziegler-Nichols tuning relations; and
   • modified Z-N settings with some overshoot and no overshoot.
     
     NOTE: Not all methods will yield a PI or PID controller for this model.
     
3. Write a SIMULINK program to compare the performance of these controller designs for setpoint changes from 1.0 to 2.0 g/l using the IAE, ISE and ITAE integral indices. Find the controller design that minimizes the amount of off-spec product after a setpoint change.
   
4. Use a trial-and-error procedure to design a controller with better performance than the controllers you designed in Part 1.3 above.
   
5. Use the mathematical model you developed for the process to generate a process reaction curve with a step change in the flow rate of the salt solution.

DATA:

Volume of tank 1 = 160 ml

Volume of tank 2 = 160 ml

Volume of tank 3 = 290 ml

Flow rate of pure water = 600 ml

Note: This flow rate is kept constant at all times

Concentration of salt solution = 14 (g salt)/(l of solution)

Reminder on Honor Code Policy: "The students may talk to each other, the labbies or the instructor about any assignment in the course that is not specifically designated as pledged. This assistance is limited to the discussion of the problem. Consulting another student's solution (even from a previous class on the same subject) is prohibited, and submitted solutions may not be copied from any source."