(115b) Enhancing the Resolution of Process Design: Incorporating High Fidelity Process Unit Models in Flowsheet Optimization

Enhancing the resolution of process design: Incorporating high fidelity process unit models in flowsheet optimization

R.C. Pattison and M. Baldea

McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712

Process design is a vital activity to the chemical industry. Given the massive and long-term investments required to carry out a green-field project or a major retrofit, there’s a significant and justifiable interest in devising optimized designs with a high level of detail around key process units.

Research progress in equation-based simulation has been steady, and some commercial simulators offer equation-oriented options as well. In this presentation, we discuss the possibility of further enhancing the resolution of equation-oriented process flowsheet models by embedding detailed models of unit operations such as reactors, multi-stream heat exchangers, etc. Such models capture physical characteristics over multiple length scales, including the (smaller) dimensions that are typically not captured at the design stage.

We begin from our previously developed concept of pseudo-transient flowsheet simulation [1-3], and show that detailed unit models described by partial-differential material and energy balance equations lend themselves naturally to a pseudo-transient reformulation. This, in turn, facilitates incorporating such models in simulation and optimization calculations at the flowsheet level.

We conclude our presentation with several design case studies pertaining to industry-relevant problems, including production of alternative fuels and natural gas processing.

References

[1] Pattison, R.P.; Baldea, M. Equation-oriented flowsheet simulation and optimization using pseudo-transient models. AIChE J., 2014, 60, 4104-4123.

[2] Pattison, R.P.; Baldea, M. Multistream heat exchangers: Equation-oriented modeling and flowsheet optimization. AIChE J., 2015, 61, 1856-1866.

[3] Pattison, R.P.; Gupta, A.M.; Baldea, M. Equation-oriented optimization of process flowsheets with dividing-wall columns. AIChE J., 2015, doi: 10.1002/aic.15060.