Simulation-based planning of shutdown operations

This paper presents a simulation-based planning approach for determining the sequence of valve operations for the shutdown in a chemical plant. In some plants, it is required to detennine a shutdown sequence in a way that avoids hazardous conditions during the removal of inventory, or the decontamination of equipment, or an entry-vessel procedure. Invariably, this type of problems introduces quantitative constraints that carmot be addressed by traditional state-planning approaches. The proposed approach is illustrated with the shutdown of mixing tank in which valve operations are automatically generated while maintaining the tank contents outside the flammability region.