1. Using an Operator Training Simulator in the Undergraduate Chemical Engineering Curriculum
Debangsu Bhattacharyya1,2,
Richard Turton1,2 and Stephen E. Zitney1
1AVESTAR Center,
NETL, Morgantown, WV
2West Virginia University,
Morgantown, WV
October 29, 2012
AIChE Annual Meeting, Pittsburgh, PA

2. Outline What is an Operator Training Simulator (OTS)
Using the OTS in undergraduate education:
Chemical Process Simulation course
Process Control Course
Conclusions

3. Operator Training Simulators
AVESTAR Center Facilities
AVESTAR Center at NETL
AVESTAR Center at WVU
Locations
NETL in Morgantown, WV
WVU, National Research Center for Coal & Energy
Facilities
OTS Room: Control Room
Divider for 2 Simulators
ITS Room: Plant/Field
Local area network
Training Systems
IGCC OTS
8 Operator Stations
2 Instructor Stations
2 Engineering Stations
IGCC ITS
2 Field Stations
1 Instructor Station
Overview AVESTAR centers – note 1 at WVU and 1 at NETL
Mention ITS but say this presentation is limited to OTS

4. IGCC with CO2 Capture Dynamic Simulator Reference Plant (2 Trains)
Plant Section
Description
Gasification
Entrained-flow Gasifier
Air Separation
Elevated-P Cryogenic ASU (95% vol O2)
H2S Separation
Physical Solvent AGR 1st Stage
Sulfur Recovery
Claus Plant
CO2 Separation
Physical Solvent AGR 2nd Stage
CO2 Compression
Four stage (2200 psia)
Gas Turbines
Adv. F Class (232 MW output each)
Steam Cycle
Subcritical (1,800 psig/1,000ºF/1,000ºF)
Power Output
746 MW gross (556 MW net)
References
IGCC Case #2, Cost and Performance Baseline for Fossil Energy Power Plants Study, Volume 1: Bituminous Coal and Natural Gas to Electricity, National Energy Technology Laboratory, DOE/NETL-2010/1397, November 2010.

5. Operator Training Simulators
This shows the basic horseshoe structure of the training center. The curved consoles at the front of the room are the operator stations – representing the control room
The consoles at the back of the room are the instructor stations – dynamic model is run on the PCs at the back of the room and information is distributed to the front consoles via the data historian and finally to the HMIs

6. Operator Training Simulators
Next two slides show the set up at the WVU center

7. Operator Training Simulators

8. Operator Training Simulators
HMI Displays for Plant Areas
Here we see two HMIs that represent simplified P&IDs of various sections of the plant. We have 21 plant sections/processes and well over 100 HMI screens.
On the right we see a pump start/stop panel and a list of permissives that need to be in place in order for the pump to be started – example of digital logic.
(Courtesy of Invensys Operations Management)

9. Operator Training Simulators
HMI Displays for Alarms and Trending
Here we see a set of 10 control panels on the left that show instrument indicators, controllers, pump/motor start/stops, etc. These can all be customized during development and are used by the operator to control and start-up/shut-down the plant. Also shown on the right hand side is a controller and a trend plot for the variable being controlled – these plots can be used for any variable for which an instrument exists, e.g., pressure, temperature, level, certain compositions, etc.
(Courtesy of Invensys Operations Management)

10. Outline What is an Operator Training Simulator (OTS)
Using the OTS in undergraduate education:
Chemical Process Simulation course
Process Control Course
Conclusions

11. Chemical Process Simulation course
Student exposure in Simulation Course
1st Lecture – discussed IGCC plant overview, key features of the OTS including:
navigation between HMI screens and plant overview screens
trending features
control panels and control operation
digital logic and permissives
alarms
links to dynamic model through data historian and the emulation of the plant
The first part of the presentation will discuss the interaction that students had with the OTS during a new process simulation course that was developed at WVU in the Spring of The actual aim of the course was to teach steady state and dynamic simulation techniques to students and to get them to build and operate a dynamic model for a chemical process – obviously much less sophisticated than the IGCC system but nevertheless very instructive. The exposure to the OTS was through a 1 hour introduction to the OTS showing the basic functionality and principles behind the system….

12. Chemical Process Simulation course
Student exposure in Simulation Course
Simulation course ran for 6-8 weeks prior to a 1-day work session by the students starting up the Claus unit. Key features covered in the 1-day session were:
Exposure to start-up procedures
Equipment preparation
Digital logic (switches and permissives)
Timing of actions
Different control strategies
Physical interpretation (analysis) of process changes
After about 8 weeks of instruction the latter 5 of which was on dynamic simulation (Dynsim – the same platform on which the IGCC OTS is built), the students spent a full day session using the OTS. The focus of the instruction was to start-up the Claus unit, which takes the H2S from the AGR unit and converts it to elemental sulfur first through a partial oxidation to SO2 and then via catalytic synthesis using the Claus reaction to form S. This process was chosen because it is relatively simple ti follow and can be started up easily within the time period. The HMIs are shown in the following pages:

13. Chemical Process Simulation course
Very quickly go over flow of main streams

14. Chemical Process Simulation course
ditto

15. Chemical Process Simulation course
Not all valves in P&ID are on HMI – remote function (RF) valves located in plant and are manually operated
Student exposure to OTS in Simulation Course
Example 1 - Start up procedures
The students were provided a set of detailed start-up instructions that they were to follow during the session
The first issue that was covered was the concept of remote function (RF) valves that do not appear on the HMI but play a crucial role in the start up – these RF valves are for isolation and are typically either open or closed.
These valves are located in the plant and are simulated in the dynamic model but do not appear on the HMI – thus if the operator skips a step that involves opening or closing an rf valve then these is an uninteded consequence that will probably mess up the startup process – OBJECT LESSON No. 1

16. Chemical Process Simulation course
Student exposure to OTS in Simulation Course
Example 2 – Digital logic and permissives
Although not covered in most u/g control courses, the use of digital logic is an important and essential part of operating a real chemical process. As part of the Claus unit start up, the Claus furnace has to go through a series of procedures and checks prior to turning on the methane and air to get the furnace up to temperature.

17. Chemical Process Simulation course
Student exposure to OTS in Simulation Course
Example 2 - Digital Logic and permissives
The previous steps in the S/U procedure involved checking that a series of valves (air, oxygen, sour gas, acid gas, natural gas, etc.) were closed. These would result in check marks in the boxes on the left. Once this was done, a nitrogen purge was initiated to sweep out any combustible gases, once that had been done air and NG could be fed to the system in the correct sequence and the burner ignited. All these actions register on the Claus R1300 sequence HMI. If the sequence is not followed exactly, the burner will not ignite and the sequence has to be reset and started again – OBJECT LESSON No. 2

18. Chemical Process Simulation course
Student exposure to OTS in Simulation Course
Example 3 – Physical Interpretation of Actions
Just with the Claus furnace start-up, there are sequences that must be followed to ensure that damage to equipment will not result. For example, in Step 301, the intermediate pressure steam generated in the Claus WHB finally reaches 570 psig and can be fed to the cold reheat header. This is done by activating (opening) MV015. However, to ensure that the pressure is balanced across the valve, rather than just opening this valve a small bleed flow is started that equalizes the pressure either side of MV015 by opening RF015 – the digital logic understands that once this valve is open that the Motor valve can open 30 s later.
There are many other examples of practical engineering considerations needed to S/U and operate a plant – the 1-day session prepares the students for their project in the simulation course in which they are also required to write up a S/U sequence for their process – OBJECT LESSON No. 3
Details of many of these aspects will be given by me in a paper on Wednesday – (560c). Now I will hand over the presentation to my colleague Debangsu Bhattachayya who will discuss some of the lessons taught in the process design course at WVU.

19. Outline What is an Operator Training Simulator (OTS)
Using the OTS in undergraduate education:
Chemical Process Simulation course
Process Control Course
Conclusions

20. Objectives
Use a state-of-the-art operator training simulator (OTS) for teaching process dynamics and control to the undergraduates
Demonstrate the real life application of the control theory
Show the students where their current course work fits into the real process plant
Demonstrate the crucial role that the control system plays
Demonstrate interactions between different equipment/systems/variables
Provide the students with a big picture view as well as finer details as much as tractable and applicable in about 4 hours of time
Need to change this slide to indicate process simulation course as well as control course

21. The Course at a Glance
The course focuses on dynamics and control of chemical processes. This is a senior year course for Chemical Engineering undergraduates. Currently there are 35 students in this class.
For the undergraduates, this is the only course so far concentrating on both process dynamics and control.
Mainly linear single input single output (SISO) systems are studied.
Only software used (of course not considering the OTS demonstrations) is Matlab/Simulink.
This is the second year when the dynamic simulator is being used in teaching this course.

22. Demonstration Outlines
The course can be broadly divided into two sections which are strongly coupled with each other:
Process dynamics
Process control
A number of demonstration such as development of first principles dynamic model, implementation of ideal forcing function, use and advantages/disadvantages of various control strategies such as ratio control, split-range control, cascade control, feedback-augmented feedforward control are demonstrated
Process Dynamics examples shown here:
Time-delay systems
Process Control examples shown here:
Open-loop unstable systems
Closed-loop stability: Proportional gain for stability limits

23. Process Dynamics Examples

24. Time-delay Systems Show how time-delay occurs in an actual plant
Coal feed to the plant is step decreased
Transient response in the CO2 composition at the inlet of the H2S absorber is recorded

25. Coal-feed/syngas flow path

26. Syngas flow path

27. Syngas flow path

28. Syngas flow path

29. Syngas flow path

30. CO2 concentration at the CO2 absorber inlet
1:32:11 pm
CO2 absorber Inlet
1:35:13 pm

31. Process Control Examples

32. Open-Loop Unstable Systems
Case 1: Closed-loop system
Case 2: Open-loop system, emergency controller takes over
Case 3: Open-loop system, No emergency controller, plant shuts down
Demonstration example: Radiant syngas cooler (RSC) steam generator

33. Case 1: Closed loop system
: Coal feed-flow is step increased
: Demonstrate control loop performance for disturbance rejection
: Demonstrate how different systems interact in an actual plant

34. Transient Response of the RSC Steam Drum Pressure

35. Interaction of the RSC steam drum with other systems
Main HP Steam Generation System

36. Interaction of the RSC steam drum with other systems
HP Steam Header

37. Case 2: Open-loop system, emergency controller takes over
: The plant still operates normally with a loss of efficiency
: Demonstrate the necessity of a “good design” for which the
dynamic consideration is crucial

38. Case 3: Open-loop system, No emergency controller, plant shuts down
: Drum level decreases to a very low level triggering a plant shutdown
:Demonstrate other “lines of defense”- emergency shutdown system

39. Closed-loop stability: Proportional Gain for Stability Limits
Students carry out closed-loop stability analysis (by Routh stability analysis, direct substitution, etc.) to determine the limiting proportional gain for stability of the closed-loop system.
Demonstration of the theory with the RSC pressure control by slowly modifying the proportional gain.
Kc=3
Kc=1
Kc=1
Kc=3
Kc=1
Kc=1

40. Practical Control Test
A few sample questions:
Choose any arbitrary flowsheet and any arbitrary controller. What are the input and output of the controller that you have selected? What are the input and output of the process that you have selected?
Draw a block diagram of the closed loop system.
Is this system open-loop stable? Why or why not? [Note: you can answer this question theoretically or by carrying out an experiment]
What are the disturbance variables(s) for this system?
Check the controller performance for servo control. How did you check it? What will you do to improve its performance for servo control further?
Check the controller performance for regulatory control. How did you check it? What will you do to improve its performance for regulatory control further?
Please note any loop interaction that you have observed while testing the regulatory control.

41. Conclusions
A state-of-the-art dynamic simulator is being used for teaching process dynamics, control, and simulation to undergraduate students.
Some examples are cited but many other possibilities exist. Your suggestions are welcome.

42. Acknowledgement
National Energy Technology Laboratory (NETL)

43. Thank You