Presented by Greg McMillan as short course for ISA St. Louis section on December 10, 2010.

1. ISA Saint Louis Short Course Dec 9-10, 2010 Advanced pH Measurement and Control - Day 2

3. Bioreactor Control - 1

4. Bioreactor Control - 2 Bioreactor VSD VSD TC 41-7 AT 41-4s2 AT 41-4s1 AT 41-2 AT 41-1 TT 41-7 AT 41-6 LT 41-14 Glucose Glutamine pH DO Product Heater VSD VSD VSD AC 41-4s1 AC 41-4s2 Media Glucose Glutamine VSD Inoculums VSD Bicarbonate AY 41-1 AC 41-1 Splitter AC 41-2 AY 41-2 Splitter CO 2 O 2 Air Level Drain 0.002 g/L 7.0 pH 2.0 g/L 2.0 g/L 37 o C MFC MFC MFC AT 41-5x2 Viable Cells AT 41-5x1 Dead Cells

5. pH Growth Rate Factor pH Growth Rate Factor

6. Convenient pH Model Kinetics pH max = maximum pH for viable cells (8 pH) pH min = minimum pH for viable cells (6 pH) pH opt = optimum pH for viable cell growth (6.8 pH)

7. Feed Reagent Reagent Reagent The period of oscillation (4 x process dead time) and filter time (process residence time) is proportional to volume. To prevent resonance of oscillations, different vessel volumes are used. Small first tank provides a faster response and oscillation that is more effectively filtered by the larger tanks downstream Big footprint and high cost! Traditional System for Minimum Variability

8. Reagent Reagent Feed Reagent Traditional System for Minimum Reagent Use The period of oscillation (total loop dead time) must differ by more than factor of 5 to prevent resonance (amplification of oscillations) The large first tank offers more cross neutralization of influents Big footprint and high cost!

10. Basic Neutralization System - Before Can you spot the opportunities for process control improvement? Static Mixer AC 1-1 Neutralizer Feed Discharge AT 1-1 FT 1-1 FT 2-1 AC 2-1 AT 2-1 FC 1-2 FT 1-2 2 diameters Reagent Stage 1 Reagent Stage 2

11. Basic Neutralization System - After Feedforward Summer Static Mixer AC 1-1 Neutralizer Feed Discharge AT 1-1 FT 1-1 FT 2-1 AT 2-1 FC 1-2 FT 1-2 10-20 diameters Reagent Stage 1 Reagent Stage 2 FC 2-1 AC 2-1 10-20 diameters f(x)  RSP Signal Characterizer *1 *1 *1 - Isolation valve closes when control valve closes

12. Tight pH Control with Minimum Capital Investment Influent FT 1-2 Effluent AT 1-1 FT 1-1 10 to 20 pipe diameters f(x) *IL#1 Reagent High Recirculation Flow Any Old Tank Signal Characterizer *IL#2 LT 1-3 IL#1 – Interlock that prevents back fill of reagent piping when control valve closes IL#2 – Interlock that shuts off effluent flow until vessel pH is projected to be within control band Eductor FC 1-2 AC 1-1 LC 1-3

14. High Uniformity Reagent Dilution Control Big old tank acts an effective filter of reagent concentration fluctuations Water FC 1-2 FT 1-2 Diluted Reagent DC 1-1 DT 1-1 FT 1-1 Reagent High Recirculation Flow Any Old Tank LT 1-3 LC 1-3 Eductor FC 1-1 Ratio Density RSP RSP

15. Cascade pH Control to Reduce Downstream Offset AT 1-2 Static Mixer Feed AT 1-1 FT 1-1 FT 1-2 Reagent 10 to 20 pipe diameters Sum Filter Coriolis Mass Flow Meter f(x) PV signal Characterizer RSP f(x) Flow Feedforward SP signal characterizer Trim of Inline Set Point Integral Only Controller Linear Reagent Demand Controller Any Old Tank M FC 1-1 AC 1-1 AC 1-2

16. Full Throttle Batch pH Control Batch Reactor AT 1-1 10 to 20 pipe diameters Filter Delay Sub Div Sum  t Cutoff Past  pH Rate of Change  pH/  t Mul Total System Dead Time Projected   pH New pH Old pH Batch pH End Point Predicted pH Reagent Section 3-5 in New Directions in Bioprocess Modeling and Control shows how this strategy is used as a head start for a PID controller

17. Linear Reagent Demand Batch pH Control Batch Reactor AT 1-1 10 to 20 pipe diameters f(x) Master Reagent Demand Adaptive PID Controller Static Mixer AT 1-1 10 to 20 pipe diameters Secondary pH PI Controller Signal Characterizer Uses Online Titration Curve FT 1-1 FT 1-2 Online Curve Identification Influent #1 Reduces injection and mixing delays and enables some cross neutralization of swings between acidic and basic influent. It is suitable for continuous control as well as fed-batch operation. Influent #2 AC 1-1 AC 1-1 FC 1-1 FQ 1-1

19. Pulse Width and Amplitude Modulated Reagent Neutralizer Reagent AT 1-1 10 to 20 diameters PWM Faster cheaper on-off valve is pulse width modulated PD Controller Cycle Time = System Dead Time Throttle valve position sets pulse amplitude Pulse width modulation is linear. The addition of pulse amplitude modulation introduces a severe nonlinearity but greatly increases the sensitivity and rangeability of reagent addition AC 1-1

20. Case History 1- Existing Control System Mixer Attenuation Tank AY AT middle selector AY splitter AC AT FT FT AT AY AT AT AT AY AT AT AT Mixer AY FT Stage 2 Stage 1 middle selector AC Waste Waste middle selector Fuzzy Logic RCAS RCAS splitter AY filter AY ROUT kicker

21. Case History 1 - New Control System Mixer Attenuation Tank AY AT middle selector AY splitter AT FT FT AT AY AT AT AT AY AT AT AT Mixer AY FT Stage 2 Stage 1 middle selector Waste Waste middle selector RCAS RCAS splitter AY filter AY ROUT kicker AC-1 AC-2 MPC-2 MPC-1

22. Case History 1 - Opportunities for Reagent Savings pH Reagent to Waste Flow Ratio Reagent Savings 2 12 Old Set Point New Set Point Old Ratio New Ratio

23. Case History 1 - Online Adaptation and Optimization Actual Plant Optimization (MPC1 and MPC2 ) Tank pH and 2 nd Stage Valves Stage 1 and 2 Set Points Virtual Plant Inferential Measurement (Waste Concentration) and Diagnostics Adaptation (MPC3) Actual Reagent/Waste Ratio (MPC SP) Model Influent Concentration (MPC MV) Model Predictive Control (MPC) For Optimization of Actual Plant Model Predictive Control (MPC) For Adaptation of Virtual Plant Virtual Reagent/Influent Ratio (MPC CV) Stage 1 and 2 pH Set Points

24. Case History 1 - Online Model Adaptation Results Adapted Influent Concentration (Model Parameter) Actual Plant’s Reagent/Influent Flow Ratio Virtual Plant’s Reagent/Influent Flow Ratio

25. Case History 2 - Existing Neutralization System Water 93% Acid 50% Caustic Pit Cation Anion To EO Final acid adjustment Final caustic adjustment AT

29. Really big tank and thousands of mice each with 0.001 gallon of acid or caustic or modeling and control Case History 2 - Choices

30. Case History 2 - Tuning for Conventional pH Control

31. Case History 2 - Tuning for Reagent Demand Control Gain 10x larger

32. Case History 2 - Process Test Results One of many spikes from stick-slip of water valve Tank 1 pH for Reagent Demand Control Tank 1 pH for Conventional pH Control Start of Step 2 (Regeneration) Start of Step 4 (Slow Rinses)

35. Streams, pumps, valves, sensors, tanks, and mixers are modules from DeltaV composite template library. Each wire is a pipe that is a process stream data array (e.g. pressure, flow, temperature, density, heat capacity, and concentrations) First principle conservation of material, energy, components, and ion charges Case History 2 - Dynamic Model in the DCS

37. Adapted Reagent Demand Control Reduces injection and mixing delays and enables some cross neutralization in continuous and batch operations Neutralizer AC 1-1 AT 1-1 10 to 20 diameters f(x) Master Reagent Demand Adaptive PID Controller Static Mixer AC 1-1 AT 1-1 10 to 20 diameters Secondary pH PI Controller Signal Characterizer Uses Online Titration Curve FT 1-1 FC 1-1 FQ 1-1 FT 1-2 Online Curve Identification Influent

39. Speed of Response Seen by pH Loop Batch processes have less self-regulation because there is no discharge flow. If there is no consumption of reagent in the batch by a reaction, the pH response is only in one direction for a given reagent. If there is no split ranged acid and base reagent in the batch, PD instead of PID and predictive strategies are used.  d  o 0 1 2 curve 0 = Self-Regulating curve 1 = Integrating curve 2 = Runaway Time (minutes) pH 0  pH Ramp Acceleration Open Loop Time Constant Total Loop Dead Time  CO (% step in Controller Output)

41. Scheduling of Learned Dynamics and Tuning Model and tuning is scheduled based on pH

42. Adaptive Control Efficiently Achieves Optimum hourly cost of excess reagent hourly cost of excess reagent total cost of excess reagent total cost of excess reagent pH pH

43. Adaptive Control Efficiently Rejects Loads hourly cost of excess hourly cost of excess pH total cost of excess reagent total cost of excess reagent pH

44. Adaptive Control is Stable on Steep Slopes pH pH

46. PID Valve Sensitivity and Rangeability Solution 1 Difficult to tune Neutralizer AC 1-1a AT 1-1 PID Controller Large (Coarse) Small (Fine) AC 1-1b P only Controller Reagent

47. PID Valve Sensitivity and Rangeability Solution 2 Difficult to tune Neutralizer AC 1-1 AT 1-1 PID Controller Large Small ZC 1-1 I only Controller Reagent

48. MPC Valve Sensitivity and Rangeability Solution Model Predictive Controller (MPC) setup for rapid simultaneous throttling of a fine and coarse control valves that addresses both the rangeability and resolution issues. This MPC can possibly reduce the number of stages of neutralization needed

49. MPC Valve Sensitivity and Rangeability Solution

50. MPC Valve Sensitivity and Rangeability Solution

51. MPC Valve Sensitivity and Rangeability Solution

52. MPC Maximization of Low Cost Reagent

53. MPC Maximization of Low Cost Reagent

54. MPC Maximization of Low Cost Reagent Riding Max SP on Lo Cost MV Riding Min SP on Hi Cost MV Critical CV Lo Cost Slow MV Hi Cost Fast MV Load Upsets Set Point Changes Load Upsets Set Point Changes Low Cost MV Maximum SP Increased Low Cost MV Maximum SP Decreased Critical CV

55. MPC Maximization of Low Cost Reagent manipulated variables Supplemental Reagent Flow SP Cheap Reagent Flow PV Neutralizer pH PV Acidic Feed Flow SP Supplemental Reagent Valve Position controlled variable constraint variable MPC disturbance variable Acid Feed Flow SP null optimization variable null Maximize Note that cheap reagent valve is wide open and feed is maximized to keep supplemental reagent valve at minimum throttle position for minimum stick-slip

58. Advanced Application Notes

59. A Funny Thing Happened (E-Book Online)

60. Elimination of Lime Delay and Lag Times FC 1-1 FT 1-1 AC 3-1 AT 3-1 LC 1-1 LT 1-1 Liquid Waste Storage Lime Conveyor < HC 2-1 Delay Lag Sum RSP Rotary Valve Speed Conveyor Transportation Delay Lime Dissolution Lag Time Feedforward Summer Low Signal Selector Neutralizer Lime Hopper Manual Loader