1. The Development of a Robust Layout Optimization Tool and its Application in the Air Separation Industry
Christina Bloebaum, T. Kesavadas, Kemper Lewis
Ken English, Anoop Nair, Deepesh Khandelwal
University at Buffalo
Ken Wong
Praxair
A Joint Development Program
Between Praxair and the
University at Buffalo Center for Advanced Design
This is a 2 1/2 year project with Praxair, a world leader in air separation. Optimization, approximation, and visualization are the three main components of this work and also three relatively ‘new’ terms to Praxair. Benefits of this project are already becoming quite clear and the shifts required in thinking at Praxair are starting to gain momentum.

2. The “Other Side” of MDO: A Multiobjective, Uncertain, and User-Centered World
Most of the work in the first 10 years in MDO dealt with precise, certain, computer-centered world. Equations were known, single objective functions were used, computers were relied on for accurate results, and finding optimal solutions to problems was the goal. More recently, there has been a shift in the MDO community to problems consisting of multiobjectives, uncertain information, user-centered solution processes where designers actively interact, and finding “close-to-optimal” solutions is the objective and even more realistic and useable.
See Lewis, K., and Mistree, F., 1998, "The Other Side of Multidisciplinary Design Optimization: Accommodating a Multiobjective, Uncertain and Non-Deterministic World" Engineering Optimization, Vol. 31, pp

3. Praxair Coldbox and Air Separation Plant
These “coldboxes” are the heart of the air separation process and range from feet tall, and 4-40 feet in diameter depending upon the gases needed from the air. Inside the coldbox are combinations of heat exchangers, condensors, pumps, turbines, tanks, drains, phase separators, and hundreds of feet of piping. Placing all these components is not trivial and typically has been done through trial and error. This project focuses on developing a methodology and associated tools to help designers place components based on a number of different objectives, visualize the layout, interactively change certain components.

4. Praxair Coldbox and Air Separation Plant

5. Component View of the CDT
Optimizer
Costing
User
Interface
Sizing Tools
HYSYS is the Praxair program that performs the heat transfer, thermodynamic analysis of the air separation process and develops a set of requirements for the coldbox. It also sizes the components to be placed in the coldbox.
HYSYS
Visualization

6. GUI of Visualizer
A designer can take any view of the coldbox, can click and drag on any component (and then re-optimize), can toggle piping on and off, and can get information on any component.

7. Validation and Verification
Research Question 2
Road-Blocks:
Validation and Verification
Are we solving the RIGHT problem, and are we solving the problem RIGHT. This is a major hurdle as different designers at Praxair have different opinions on what the RIGHT problem is.

8. Role of Near-Optimal Solutions
Research Question 3
Research Needs:
Role of Near-Optimal Solutions
Multiobjective Tradeoffs/Preference Handling
Role and Benefits of Visualization Before, During, and After Optimization
Achieving an accurate, but not 100% precise costing estimate is Praxair’s goal. If they can get within 90% of the actual price, they are very happy. If they can get to within 95%, they are extremely happy.
Various designers at Praxair have different views on what should be the driver for the coldbox design: cost, layout volume, piping flow, some subset of cost. Handling and integrating these preferences within this tool is a large need that has been identified.
Visualization of the coldbox BEFORE production is a new paradigm at Praxair. How their designers relate and use the information conveyed in the interactive visualization interface will be very valuable to future development of decision support tools in the design of large-scale systems.