Fluor has found dynamic simulation to be a powerful tool in the study of plant operation and control schemes for a facility during design. Dynamic simulation can facilitate new control concepts and more sophisticated hardware including microprocessors and computers. Better control of a process can lead to more uniform product quality and significant profitability gains. Tighter control may even be necessary for safety or environmental reasons. For some processes, greater integration and more severe operating conditions in process design may save energy, improve yield and reduce cost. These measures often complicate process control, adversely affect plant flexibility and may introduce serious problems during startup and shutdown. Dynamic simulation can test alternative control schemes before commitment to a final design, avoiding lost time during startup and avoiding expensive problems in the field. Fluor has used dynamic simulation in many studies involving process dynamics. In this paper the objectives, approach and findings for a few projects will be discussed.