1. Standards Certification Education & Training Publishing Conferences & Exhibits Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless MPC Application for Dividing Wall Column Control University of Texas, Eastman and Emerson Process Management research project

2. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Presenter Terry Blevins This presentation is based on the Emerson Exchange presentation by Willy Wojsznis and Terry Blevins – Emerson, Bailee Roach – University of Texas at Austin and Thomas Lamp – Eastman.

3. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Agenda Introduction Dividing Wall Column (DWC) Control Challenges Model Predictive Control for DWC PredictPro-MPCPro Adapting MPCPro for Wireless Operation DWC Test Results Business Results and Conclusions

4. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DWC Design ABAB A B

5. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DWC Design ABCABC A B C

6. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DWC Design ABCABC A B C

7. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DWC Pilot Plant Dividing Wall Column (DWC) at the University of Texas at Austin, Separation’s Research Program May 2015

8. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DWC - MPC Control of Temperatures Compensates for process interaction associated with temperature control May be layered on basic control strategy with no changes in configuration MPC configuration: Control/Constrained Variables – Rectifying/Upper, Mainfrac/Lower, Stripper/Bottom, and Prefrac Temperatures Manipulated Variables – Reflux, Side Stream, Reboiler Steam flow and Liquid Split Disturbance Variables – Feed flow U L B P

9. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA DeltaV Predict/PredictPro – Key Features Graphical Configuration with DeltaV Control Studio Fully integrated with DeltaV Database and Historian Automated Plant Testing and Model Identification Off-line Simulator for Testing and Operator Training Standard Operator Displays for On-line Control Embedded Flexible LP Optimization Scalable, Practical, EASY to Use

10. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Why Wireless for DWC? Instrumentation Cost Flexibility Maintenance Easy Expansion

11. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Basic Requirements to Wireless Control Provide stable operation at significantly slower scan rate than with wired control Scan rate can change in a wide range Achieve insignificant performance change as compared to wired control Provide switchover to a safe mode if wireless connection will be lost for excessive period of time

12. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC process modeling

13. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC operation diagram SP Trajectory CV Prediction Process Control Algorithm - - Setpoint (SP) Disturbance (DV) Manipulated (MV) Model output correction Future CV Future SP Error Vector Model output DV Controlled (CV)

14. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC controller generation In embedded MPC controller we want to avoid on-line matrix inverse DMC type controller generated off-line: PredictPro generates MPCPro controller matrix with defaults prediction horizon = 120 control horizon = 16 penalty on error = 1 and calculates penalty on moves from the model.

15. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How MPC may work with wireless measurements MPC uses internal model SP Trajectory CV Prediction Process Control Algorithm - - Setpoint (SP) Disturbance (DV) Manipulated (MV) Model output correction Future CV Future SP Error Vector Model output DV Controlled (CV) Wireless Retain the last measurement value, until a new wireless measurement value is available Do not apply prediction correction, until a new wireless measurement value is available

16. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How wireless measurements may affect MPC operation Uncorrected process output prediction at the time k, Past Future k k+1 k+..... Time Step 2 Step 3 Step 1 Predicted process output at the time k-1 Corrected process output prediction at the time k, CV Step 1 - Update time Step 2 – Update effect of MV change Step 3 – Correct prediction

17. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC operation when measurement fails AI measurement value t AI Status Bad AI value is simulated MPC Controller Scan MPC will use simulated AI value up to the maximum time period defined MPC mode changes to Manual or Local if AI status is Bad longer than predefined time period AI Status Good MPC Mode Auto

18. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC operation with Lab data input Lab sample reading - AI t New Lab value (AI Status Good) MPC Controller Scan MPC use simulated Lab value (AI Status Constant)

19. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How MPC Can Be Used with Wireless Measurements If the status of a Controlled, Constraint, or Disturbance input to the MPCPro block is Bad or Constant, the actual mode can automatically go to Man or continue in Auto using the simulated value instead of the bad/constant value. To enable MPC using the simulated value AI status should be set Constant, except when a new value is transmitted. In general – MPC or other model based controller can be easy adopted for wireless/event based operation.

20. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How to set wireless for AI - code

21. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How to set MPC for using simulated CV Additional parameters settings: SIM_TIME_FACTOR : Time expressed in multiples of Time to Steady State that the simulated value of a Control or Constraint parameter that has been configured for Simulate failure action is used in control before the MPCPro block takes the configured shed mode action. Time to Steady State = 120 scans PredictPro allows set up wireless operation scan period equal up to hundreds of MPCPro control periods. This fully satisfies wireless operation requirements

22. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA How to set wireless AI/CV Wireless measurement t New value is transmitted (Status Good) Controller Scan MPC uses simulated value (Status Constant) AI/CV STATUS should be managed as follows: After AI value changes – AI STATUS is Good for somewhat more than one MPC scan Otherwise AI STATUS is Constant

23. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless MPC for DWC – Operation screen Timer shows how much time left to operate using simulated CV value, before going to Local or Manual Timer is set by SIM_TIME_FACTOR Timer should be set for a maximum wireless AI transmission period (maxTP) + safety margin If several (n) AI connected, they may transmit sequentially. To avoid switching to Local or Manual Timer setup should be: Timer Setup > maxTP +n*MPCscan + safety margin Timer

24. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC on-line operation – measurement updates Calculated Status – Top Temperature Wireless Measurement of Top Temperature Reflux Flow SP

25. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC – On-line Operation - Simulation Step response “bumps” when wireless measurement updates Top Temperature Reflux Flow SP Wireless AI 16 sec update or 1% change

26. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless MPC performance - simulation Wired vs wireless MPC IAE on DWC Set Point changes Set Point change 10% IAE - Wired MPC Scan 1 s IAE-Wireless MPC Update period 8 s IAE-Wireless MPC Update period 16 s Upper Temperature126.05133.2135.1 Prefrac Temperature403.6412.5412.9 Lower Temperature129.5136.0140.1 Bottom Temperature81.488.788.2 ￭ Test proved MPC stable operation with four CV and one DV using wireless control ￭ Step responses with wireless control showed slightly lower performance ( about 10% - depends on the model quality) as compared to wired MPC ￭ In general, good process model for wireless MPC is even more important than for wired MPC (significant portion of time MPC works on model with no correction)

27. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC – Automated Process Test DeltaV PredictPro applies PRBS simultaneously on all manipulated variables.

28. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC Model – Data for Model Generation

29. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC - Model Creation The data collected during the automated test was used to generate model of the simulated process. The model that was identified is illustrated in the following screen capture.

30. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC Model – Top Temp vs Reflux Flow

31. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC – Model Verification The accuracy of the identified models may be examined using the model verification feature of DeltaV PredictPro.

32. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC Control – 30/70 Split

33. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA MPC Control – Temperature Response for 10% Feed Reduction, 50-50 Split 10% Reduction in Feed

34. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless MPC – On-line Operation Trend “bumps” when wireless measurement updates model

35. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless PID (left) vs wireless MPC Top composition control

36. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless PID (left) vs wireless MPC sidedraw composition control

37. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Wireless PID (left) vs wireless MPC Bottoms composition control

38. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Summary – Business Results The control performance achieved using a wireless MPC outperforms PID control strategies for DWC The wireless MPC performed excellent at DWC stable operation, temperatures transition to new column states and at big feed flow changes The MPC control facilitated achieving better results with DWC research design and makes PredictPro product a basic control tool for future DWC installations.

39. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Where To Get More Information T. Blevins, W. K. Wojsznis and M. Nixon, Advanced Control Foundation – Tools, Techniques, and Applications, ISA. 2012, Chapters 8, 11, 12. T. Blevins, D. Chen, M. Nixon, W. K. Wojsznis, Wireless Control Foundation – Continuous and Discrete Applications, ISA 2014 Rewagad, R. R., and Kiss, A. A., “Dynamic optimization of a dividing-wall column using model predictive control,” Chemical Engineering Science, 68 (2012) 132–142 DeltaV BOL – Release 10 and higher

40. Process Control & Safety Symposium 2015 9-12 November Houston, Texas USA Thank You Questions