Online Courseware - Dr. Sahlodin

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