Economic Model Predictive Control and Process Equipment: Control-Induced Thermal Stress in a Pipe

Abstract

Recent work on economic model predictive control (EMPC) has indicated that some processes may be operated in a more economically-optimal fashion under a time-varying operating policy than under a steady-state operating policy. However, a concern for time-varying operation is how such a change in operating policy might impact the equipment within which the processes being controlled are carried out. While under steady-state operation, the operating conditions to which equipment would regularly be exposed can be estimated, this would be more difficult to assess thoroughly a priori under time-varying operation. It could be explored whether the EMPC could be made aware of any impacts the control actions that it chooses might have on equipment, and then to seek to impose constraints on these impacts. This would require explicit consideration of equipment design, material properties/behavior, and material loading at the EMPC design stage. This work provides an initial exploration of this topic by seeking to extract principles related to the integration of equipment material fidelity considerations and EMPC through an example accounting for a simple preliminary case of thermal stresses in a pipe at equilibrium conditions.