Process modeling and simulation
Instructor: Ali M. Sahlodin
Level: Graduate

Course outline Modeling and simulation are key tools for design, performance evaluation, and optimization of chemical processes. This course aims to familiarize graduate students with advanced topics in this area, especially modeling and simulation of transient processes. Dynamic models resulting from real-life examples of transient processes along with solution methods are discussed. Also, common techniques for plant-wide process simulation in both steady and dynamic states are presented.

 
 
Lecture slides

Dynamic Simulation	Lecture 1	Introduction: importance of modeling and simulation in design and analysis of chemical processes; course scope and outline; evaluation scheme.
	Lecture 2	Steady-state and dynamic modeling with industrial examples; models involving ordinary differential equations (ODEs), partial differential equations, and differential-algebraic equations (DAEs).
	Lecture 3	Importance of DAEs in modeling chemical processes; basic definitions such as index; challenges of solving DAEs.
	Lecture 4	Advantages of DAE form; constraint drift and constraint stabilization techniques.
	Lecture 5	DAE index reduction; Pantelides structural analysis.
	Lecture 6	Consistent initialization of DAEs.
	Lecture 7	Numerical ODE methods and issue of stability.
	Lecture 8	Numerical DAE methods: multi-step methods (BDF); solution speed vs. stability.
	Lecture 9	Sensitivity analysis of differential equations: finite differences, forward sensitivity.
	Lecture 10	Sensitivity analysis of differential equations: forward and adjoint sensitivities.
	Lecture 11	Hybrid discrete/continuous dynamic systems: terminology and chemical process examples.
	Lecture 12	Hybrid discrete/continuous dynamic systems: terminology and chemical process examples (cont’d).
	Lecture 13	Simulation of hybrid discrete/continuous dynamic systems: event detection and location methods.
	Lecture 14	Simulation of hybrid discrete/continuous dynamic systems: event detection and location methods (cont’d); mode transition and re-initialization.
	Lecture 15	Simulation of hybrid discrete/continuous dynamic systems: re-initialization (cont’d).
	Lecture 16	Parametric sensitivities in hybrid dynamic processes.
	Lecture 17	Methods for simulation of hybrid dynamic processes: hybrid automaton, optimization, and nonsmooth methods; applications to simulation of equilibrium phase regime change.
Plant-wide Simulation (steady state and dynamic)	Lecture 18	Structure of process simulators; custom unit modeling; techniques for steady-state process simulation: sequential-modular simulation.
	Lecture 19	Sequential-modular simulation: partitioning and recycle handling.
	Lecture 20	Recycle handling: stream tearing criteria.
	Lecture 21	Recycle handling: stream tearing using optimization, information recycling, solving recycle loops.
	Lecture 22	Solving recycle loops: direct substitution and its modifications, Newton based methods (secant, Broyden).
	Lecture 23	Newton based methods (cont’d), process examples, final notes on sequential-modular simulation, Equation-oriented (EO) simulation, simultaneous-modular simulation.
	Lecture 24	Plant-wide dynamic simulation: applications, common dynamic simulators, transition from steady-state to dynamic simulation, pressure-flow networks, sizing, controller setup. Solution methods: modular, fully simultaneous, and semi-simultaneous methods, troubleshooting a dynamic simulation case.

 
 
Learning codes

Description	Related topic	Code compatibility
Constraint drift resulting from solving a high-index DAE as an ODE	DAEs	Octave & MATLAB
Solving a DAE using DASPK in Octave	DAEs	Octave
Solve Pendulum using Forward Euler	DAEs	Octave & MATLAB
Forward sensitivity for ODEs	Parametric ODEs	Octave & MATLAB
Bouncing ball example. Compatible with MATLAB and Octave with a small change	Hybrid dynamic systems	Octave & MATLAB
Tearing using optimization code	Sequential-modular simulation: optimal recycle tearing	Octave

 
 
Sample assignments
 

Assignment	Related topic
Assignment 1	DAE differentiation and constraint drift, implicit ODEs
Assignments 2-3	Consistent initialization, solution, and constraint stabilization of DAEs,Sensitivity analysis
Assignment 4	Hybrid discrete/continuous dynamic systems
Assignment 5	Steady-state flowsheeting: partitioning and recycle solutions, EO simulation