Controller design for pH neutralization process under neutral region

1. COMPARATIVE ANALYSIS OF P/PI/PID CONTROLLERS FOR pH
NEUTRALIZATION PROCESS
Paper I.D.-1027
Presented By,
Chandra Shekhar (M.Tech Scholar)
Supervised By,
Mr. S.K. Sharma
Asst. Professor
Chemical Engineering Department
Deenbandhu Chhotu Ram University of Science and Technology
Murthal (Haryana) India

2. Content
• pH systems
• Controllers
• Simulation
• Response of P Controller
• Response of PI Controller
• Response of PID Controller
• Conclusion
• References

3. pH System
• pH(Potential of Hydrogen) is a numeric scale used to specify the acidity and basicity of an aqueous solution.
• It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units
of moles per liter, of hydrogen ions.
• pH play an important role in waste water treatment plant of chemical, Pharmatutical industries etc. for
discharging waste water in environment.
• pH of waste water neutralize in system.
• pH neutralization process in CSTR.
• Digital pH measuring probe used to measure pH of the system.
• HCL used to neutralize Alkaline water.
• NaOH used to neutralize Acidic water.
• Controllers designed in Neutral Region.
• FOSPDT

4. Controllers
• P Controller
1. P controller produce an output signal proportional to the error.
2. P controller gives higher overshoot.
3. P controller shows higher settling time.
• PI Controller
1. PI controller consist proportional action and integral action of error.
2. PI Controller gives lower overshoot compare to P controller.
3. PI controller shows lower settling time compare to P controller.
• PID Controller
1. PID controller consist proportional, integral and derivative action of error.
2. PID controller gives lower overshoot.
3. PID controller shows lower settling time.
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5. Simulation
• All simulations performed on MATLAB 4.0(control system design and
simulation software)
• Transfer function of CSTR neutralization process.
• All simulation run at t=20, 100 sec.
• Robustness Analysis.
• Time domain Analysis.
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6. Response of P Controller
S.No. Method KC
Robustness Analysis Time Domain Analysis
IAE ISE ITAE Tr
TS
1 Zeigler-Nichols 20.5 56.95 88.95 1316 2.27 9.25
2 Cohen-Coan 24.37 24.37 77.94 1136 1.9 11.25

7. Response of PI Controller
S.No. Method KC
Robustness Analysis Time Domain analysis
IAE ISE ITAE Tr
TS
1. Ziegler-Nichols 18.636 1.667 16.16 39.81 133.8 2.32 50
2. Cohen-Coan 21.15 1.2574 20.65 42.82 239.3 2.2 74.75
3. Tayrus-Luyben 12.8125 4.4 8.401 42.19 8.148 2.65 14.25
I

8. Response of PID Controller
S.No. Method Robustness Analysis Time Domain Analysis
IAE ISE ITAE Tr TS
1. Ziegler – Nichols 24.1176 1 0.25 27.32 44.87 539.1 2.06 84.75
2. Cohen-Coan 34.1018 1.1567 0.17697 33.7 75.33 557.4 1.85 83.75
3. Tayrus-Luyben 18.6364 4.4 0.3174 8.058 36.59 11.17 2.231 19.75
4. Marlin 2.355 1.38 1.1786 26.15 107.4 96.54 8 29.74
5. Smith et al. 2.316 1.3831 1.707 26.79 101.3 117.7 8 38.25
6. Branica et al. 2.66 1.8621 2.912 27.16 110.1 106.8 6.46 34.25
CK

9. Conclusion
• P/PI/PID controllers are designed for pH neutralization system by different controller
tuning methods.
• All methods are worked in direction of settling the process variable to a desired set
value.
• In P controller IAE, ISE and ITAE are very minimum by Cohen and Coan method as
compared to other controller tuning methods, this controller shows stability but not
attained proper desired value.
• In PI controller IAE, ISE and ITAE are very minimum by Tayrus and Luyben method
as compared to other controller tuning methods, this controller shows stability but
more oscillation in response to attain desired value.
• In PID controller IAE, ISE and ITAE are very minimum by Tayrus and Luyben
method as compared to other controller tuning methods. This controller shows good
stability and robustness for the process without taking more oscillation to attain
desired value.

10. References
• Tyreus, B. D.; Luyben, W. L. Tuning PI controllers for integrator/dead time
processes. Ind. Eng. Chem. Res. 1992, 2625−2628
• S.Sakthiya Ram, D. Dinesh Kumar and B.Meenakshipriya, Designing of
PID controllers for pH Neutralization process, Indian Journal of Science
and Technology, 2016;vol. 9(12).
• Thomas E. Marlin, Designing Processes and Control System for Dynamic
Performance; 2015; Edition 2nd, McGraw-Hill Inc.
• Seborg, Edgar, Mellichap, Doyle, Process Dynamics and control; 2011;
Edition 3rd page no. 223-225.
• Donald R. Coughanour, Process System Analysis and Control; 1991;
Edition 2nd page no. 54.
• McAvoy TJ, Hsu E, Lowenthals S. Dynamics of pH in controlled stirred
tank reactor. Industrial Engineering Chemistry Process Design and
Development. 1972; 11(1):68–70.
• O’Dwyer A. Handbook of PI and PID Controller Tuning Rules. 2006; 2nd
edition, World Scientific Singapore.